Apparatuses and methods for maintaining PH in nickel electroplating baths

The nickel sulfamate bath is a well-known electrolyte formulation used in many advanced nickel plating applications, including various wafer level packaging (WLP) applications and various engineering applications where low stress films are essential. .. Such baths are typically dissolved nickel sulfamic acid salts, boric acid, as well as small amounts of one or more plating additives (eg, membrane stress relaxants and glazes) to alter the precipitation surface and stress properties, depending on the formulation. It is composed of saccharin as an agent). In some systems, chloride ions are added to aid in proper dissolution at the nickel anode and to facilitate maintenance, especially when not using a negative sulfur-containing nickel anode. Usually, the target acidity of such a bath is as wide as the pH range of about 3.0 to about 5.0 and may be further limited to the range of 3.5 to 4.5.

In a typical nickel electroplating process flow, as used in conventional wafer level packaging (WLP) applications, multiple semiconductor wafers are sequentially plated in each nickel sulfamate bath. If the composition of the bath is uneven, the quality of electroplating will be inferior, the processing performance may deteriorate, and defects may occur in the plated nickel layer. Therefore, each wafer is plated under substantially the same processing conditions. However, in the process of plating a large number of wafers, it is ideal that there is relatively no change in time and it is constant. However, in practice, maintaining constant treatment conditions in the nickel sulfamate bath can be a daunting task.

Disclosed herein is an electroplating system for electroplating nickel on a semiconductor substrate. This system is an electroplating tank (cell) configured to hold the electrolyte solution during electroplating, and has a wafer holder for holding the wafer during electroplating, an anode chamber, and nickel during electroplating. An electroplating tank may be provided with an anode chamber configured to hold the anode, the system as the electrolyte solution flows into the anode chamber during electroplating and during non-electroplating pauses. Also, an oxygen scavenger configured to reduce the concentration of oxygen in the electrolyte solution may be provided. In some embodiments, the electroplating tank of the system is a porous separator located between the anode and cathode chambers that allows ionic current to pass during electroplating but blocks the passage of electrolyte solution. Further quality separators may be provided. In some embodiments, the porous separator may be capable of maintaining a difference in oxygen concentration between the anode and cathode chambers, and in some embodiments, the porous separator is substantially an ion exchange site. It may be a porous membrane without a cathode.

In some embodiments, when the electroplating system is not electroplated, the electrolyte continues to flow into the anode chamber during some or all pauses. In some embodiments, the oxygen scavenger may be configured to reduce the oxygen concentration in the electrolyte solution flowing into the anode chamber during some or all rest periods. In some embodiments, the oxygen scavenger measures the oxygen concentration in the electrolyte solution flowing into the anode chamber during some or all pauses, and the pH of the electrolyte solution when in contact with the nickel anode during the pauses. May be configured to be lowered to a level where does not rise significantly. In some embodiments, the oxygen scavenger is configured to reduce the oxygen concentration in the electrolyte solution to a level of about 1 ppm or less. In some embodiments, the oxygen scavenger is configured to reduce the oxygen concentration in the electrolyte solution to a level of about 0.5 ppm or less. In some embodiments, the system is configured to expose the electrolyte solution to the atmosphere while electroplating nickel on the substrate.

In some embodiments, the electroplating system connects the fluid inlet into the anode chamber, the fluid outlet out of the anode chamber, the fluid inlet and the fluid outlet, and the electrolyte while electroplating nickel on the substrate. It may further include an anode chamber recirculation loop configured to allow the solution to flow into the anode chamber. In some embodiments, the electroplating system may further comprise a bath tank installed outside the electroplating tank for holding the electrolyte solution, the bath tank comprising a fluid inlet and a fluid outlet, the fluid inlet. And the fluid outlet is connected to the anode chamber recirculation loop. In some embodiments, the oxygen scavenger comprises a deaerator installed in the anode chamber recirculation loop upstream of the anode chamber and downstream of the bath tank.

In some embodiments, the electroplating system connects to a fluid inlet into the cathode chamber, a fluid outlet from the cathode chamber, a fluid inlet and a fluid outlet in the cathode chamber, and at the fluid inlet and outlet of the bath tank. It may further include a cathode chamber recirculation loop which is also connected, and the cathode chamber recirculation loop is configured to allow the electrolyte solution to flow into the cathode chamber while the substrate is electroplated with nickel. In some embodiments, the oxygen scavenger may include a deaerator installed in the anode chamber recirculation loop upstream of the anode chamber and downstream of the bath tank, and the deaerator may include cathode chamber recirculation. Not installed in the loop. In some embodiments, the system may further include a filter installed in the anode chamber recirculation loop upstream of the anode chamber and downstream of the oxygen scavenger and bath tank, the filter removing particles from the electrolyte solution. It is configured to be removed. In some embodiments, the oxygen scavenger may include a device for sparging the electrolyte solution with a substantially oxygen-free gas.

In some embodiments, the electroplating system may further comprise a pH meter configured to measure the pH of the electrolyte solution. In some embodiments, the electroplating system may further include logic circuits for operating the oxygen scavenger in response to the value output by the pH meter. In some embodiments, the electroplating system may further comprise an oxygen sensor configured to measure the oxygen concentration in the electrolyte solution.

In some embodiments, the electroplating system is in contact with the counter electrode with an electrical contact of the substrate configured to provide a voltage bias to the substrate while the substrate is held in the substrate holder. Free hydrogen ions are generated in the electrolyte solution when a sufficient positive voltage bias is applied to the electrical contact of the counter electrode, which is configured to supply a voltage bias to the counter electrode, and the electrical contact of the counter electrode. A negative voltage bias to the constructed acid-generating surface and the electrical contact of the counter electrode is supplied to the electrical contact of the substrate to be sufficient to reduce nickel ions from the electrolyte solution and plate the substrate surface. It was configured to provide a positive voltage bias to the electrical contact of the counter electrode to the acid generating surface enough to generate free hydrogen ions on the acid generating surface, thereby lowering the pH of the electrolyte solution, 1 It may further include one or more power units. In certain such embodiments, free hydrogen ions are generated on the acid generating surface by electrolysis of water molecules in the electrolyte solution. In some embodiments, the acid-generating surface is a body containing a conductive, corrosion-resistant material that does not substantially corrode in the electrolyte solution, and a coating on the body, such as platinum, platinum, niobium, ruthenium, iridium. , And a coating containing any one or more metal oxides selected from the oxides of tantalum. In some embodiments, the conductive and corrosion resistant material is titanium, tantalum, niobium, or zirconium. In some embodiments, the electroplating system is an acid generating bath tank having a fluid inlet and a fluid outlet, designed to hold a volume of electrolyte solution, with an internal acid generating surface. The acid generation bath tank and the fluid outlet of the acid generation bath tank are fluidly connected to the fluid inlet of the anode chamber and / or the fluid inlet of the cathode chamber, and the fluid inlet of the tank is connected to the fluid outlet of the anode chamber and / or the fluid of the cathode chamber. It may be provided with a recirculation loop of the acid generating bath tank that fluidly connects to the outlet, and the electrical contact of the counter electrode further has a voltage via to the counter electrode installed in the acid generating bath tank.

Further, what is disclosed in the present specification is a porous separator between the nickel anode, the cathode chamber, and the anode chamber and the cathode chamber, which allows an ionic current to pass through during electroplating but allows an electrolyte solution to pass through. Is a method of electroplating nickel on a semiconductor substrate in an electroplating tank having an anode chamber containing a porous separator to prevent. In some embodiments, the method reduces the oxygen concentration in the electrolyte solution to about 1 PPM or less, allows the reduced oxygen concentration electrolyte solution to flow into the anode chamber, and an anode the reduced oxygen concentration electrolyte solution. It may include contacting with the nickel anode in the chamber and electroplating the nickel from the electrolyte solution onto a substrate in the cathode chamber. In certain such embodiments, the electrolyte solution may be maintained at a pH of about 3.5 to 4.5 in the cathode chamber. In some embodiments, the method may further include a method of flowing the electrolyte solution into the cathode chamber, where the oxygen concentration in the electrolyte solution flowing into the anode chamber is lower than the oxygen concentration in the electrolyte solution flowing into the cathode chamber. In some embodiments, lowering the oxygen concentration in the electrolyte solution may further include lowering the concentration to about 0.5 PPM or less. In some embodiments, the temperature of the electrolyte solution during electroplating is higher than about 40 degrees Celsius. In some embodiments, lowering the oxygen concentration in the electrolyte solution involves degassing the electrolyte solution. In some embodiments, lowering the oxygen concentration in the electrolyte solution involves sparging the electrolyte solution with a gas that is virtually oxygen-free. In some embodiments, the gas that is substantially oxygen-free is an inert gas. In some embodiments, the inert gas comprises nitrogen and / or argon. In some embodiments, the method senses the pH of the electrolyte solution in the electroplating tank and the sensed pH is about 4. It may further include sending an alert if it is above 5. In some embodiments, the method senses the pH of the electrolyte solution in the electroplating tank and, if the sensed pH is above about 4.5, in the electrolyte solution before the electrolyte solution flows into the anode chamber. It may further include further lowering the oxygen concentration of the. In some embodiments, the method senses the oxygen concentration of the electrolyte solution in the anode chamber and, if the sensed oxygen concentration is above about 1 PPM, the electrolyte solution before the electrolyte solution flows into the anode chamber. It may further include further lowering the concentration of oxygen in.

Further, the present specification discloses that the pH of the electrolyte solution is higher than about pH 4.5 while electroplating nickel from the electrolyte solution onto a semiconductor substrate in an electroplating tank having an anode chamber and a cathode chamber. Is also a way to prevent it from rising up. In some embodiments, the method may include reducing the oxygen concentration in the electrolyte solution to about 1 PPM or less before the electrolyte solution flows into the anode chamber of the electroplating tank.

<figref num="1A">It is a graph of the pH level of the nickel sulfamate bath when it was not used for the plating operation for 40 days.</figref><figref num="1B">FIG. 5 is a graph of pH levels when several nickel sulfamate electroplating bath solutions are maintained at 55 degrees Celsius in Erlenmeyer flasks under four different conditions over several days.</figref><figref num="1C">It is also a graph of the pH level when some nickel sulfamate electroplating bath solutions are maintained at 55 degrees Celsius in Erlenmeyer flasks under various conditions for several days.</figref><figref num="2">It is a graph which shows the amount of sulfamic acid required to return the bath which is composed of nickel sulfamate 75 g / L and boric acid 30 g / L from the state where it exceeds pH 4 to pH 4.</figref><figref num="3A">It is a perspective view of the apparatus which holds and positions a wafer for electrochemically processing a semiconductor wafer.</figref><figref num="3B">It is a figure which showed the detailed part of the conical part and the cup part of the apparatus which holds and positions a wafer in a cross-sectional form.</figref><figref num="3C">It is a schematic diagram of one mounting embodiment of an electroplating tank having an anode chamber and a cathode chamber according to the specific embodiment described in this specification.</figref><figref num="3D">FIG. 6 is a schematic representation of an electroplating system with three separate electroplating modules and three separate electroplating post-treatment modules.</figref><figref num="4A">Electroplating solution flow in the electroplating bath of the system when being a schematic view of an electroplating system using oxygen reducing apparatus for reducing the oxygen concentration in the electroplating solution.</figref><figref num="4B">FIG. 5 is a schematic representation of another embodiment of an electroplating system that uses an oxygen scavenger to reduce the oxygen concentration in the electroplating solution as the electroplating solution flows into the electroplating tank of the system.</figref><figref num="5A">It is a schematic diagram of one embodiment of an acid generating surface (AGS) designed in a disk-like configuration so that it can be inserted into an electroplating tank instead of a semiconductor substrate.</figref><figref num="5B">It is the schematic of the electroplating apparatus which has the integrated AGS component which is the form of the AGS ring mounted on the inner wall of an electroplating tank.</figref><figref num="5C">FIG. 6 is a schematic representation of an acid generating bath tank comprising a container configured to hold a certain volume of electroplating bath fluid, with both AGS and counter electrode located within the container and in contact with the bath fluid.</figref><figref num="6">It is a schematic process diagram of the electroplating method including lowering the oxygen concentration in an electrolyte solution, and flowing an electrolyte solution with a lowered oxygen concentration into an anode chamber of an electroplating tank.</figref><figref num="7">It is a graph of the pH level with respect to time, and is a figure which shows how the pH fluctuation observed in the resting nickel electroplating bath solution is remarkably reduced by oxygen removal.</figref>

In this specification, the terms "semiconductor wafer", "wafer", "board", "wafer substrate", and "partially manufactured integrated circuit" are used interchangeably. One of ordinary skill in the art will appreciate that the term "partially manufactured integrated circuit" may refer to a silicon wafer at any stage of many integrated circuit manufacturing stages. The following detailed description assumes that the present invention is practiced on wafers. The diameter of a semiconductor wafer is usually 200, 300 or 450 mm. However, the present invention is not limited to this. Workpieces can be of various shapes, sizes and materials. In addition to semiconductor wafers, other workpieces that may be advantageous to the present invention include various articles such as printed circuit boards.

The following description provides a number of specific details to give you a complete understanding of the embodiments presented. The disclosed embodiments can be implemented without some or all of these particular details. Moreover, in order not to unnecessarily obscure the disclosed embodiments, the known processing operations are not described in detail. The disclosed embodiments will be described in conjunction with specific embodiments, but it will be understood that there is no intention to limit the disclosed embodiments.

Nickel precipitation and electroplating are expected to have various uses in semiconductor manufacturing. For example, electroplated nickel is especially important for wafer level packaging (WLP) applications, where it is expected to be commonly used and used as a material to form "underbump diffusion barriers". Often. In such a process, nickel may be deposited between the "rewiring layer" (often copper) formed on the integrated circuit and the solder balls or "bumps". The bumps are solder formed on top of nickel. Generally, tin silver or tin lead solder is used. Solder may be formed by electroplating or other processes. Nickel is deposited to a thickness of more than 1 micrometer in certain applications. Generally, 2 to 3 micrometers are used.

However, in order to achieve stable, high-quality nickel plating, it is important that the composition of the electroplating bath and the plating treatment conditions remain substantially constant in the process of sequentially plating many wafers. Keeping the pH level of the bath within a particularly optimal range has proven to be of utmost importance.

The electrolytic bath solution used in the nickel electroplating operation is often based on the chemistry of nickel sulfamate, but other chemistry of nickel salts may be utilized. Such baths are readily available from a variety of commercially available sources. These nickel sulfamate solutions typically have a target pH of about 4 during electroplating and an acceptable pH operating range of about 3.5 to 4.5. Nickel films precipitated using a nickel electrolytic bath solution whose pH level is outside this operating range usually have higher internal stresses, and the fine structure of the nickel films often mechanically collapses, which is a viewpoint of IC manufacturing. Clearly unacceptable from.

Unfortunately, it would be certain to adjust the pH levels of the nickel sulfamate baths first, but experience has shown that the pH levels of these baths tend to rise during the process of plating multiple wafers. Therefore, it is difficult to maintain the pH level within the optimum range. Specifically, the pH level is measured substantially monotonously, and in some cases proportionally, over time and / or as the total amount of nickel electroplated-eg, the total charge plated. It tends to increase according to the total amount of plating. Although not limited to a particular theory, this increase in pH during electroplating-the time the charge is transferred to the wafer-is not 100% effective in the electrochemical reaction leading to nickel precipitation on the wafer. A side reaction occurs at the same time as the main electroplating reaction, which is thought to be due to the tendency to consume hydrogen ions in the bath.

It is also possible that the nickel sulfamate electroplating bath tends to have elevated pH levels even during periods of rest when there is no electrochemical plating operation-that is, there is no charge to move to the wafer. The inventors have confirmed. This problem is illustrated in Figure 1A, which shows the pH level of a nickel sulfamate bath for 40 days without any plating work. Starting with an initial pH level slightly below 4.2, the pH level of the bath exceeded the upper limit (USL) of 4.5 long before the 5th day of hibernation, and after 20 days the pH level reached about 5, 20 From the 1st day to the 40th day, there is still a slight upward trend.

Several experiments were also conducted in an attempt to isolate and identify the possible causes of pH fluctuations during the rest period. As a result, the increase in pH of the nickel sulfamate bath, which approaches and exceeds pH 4.5 during the rest period in large-scale measurements, is due to the presence of activated nickel anodes and significant levels of oxygen dissolved in the bath. Experiments have shown that it depends on both gas and gas.

For illustration, Figure 1B shows several nickel sulfamate electroplating bath solutions (Ni200 solution available from Enthone, see below) in an Ellenmeier flask at 55 degrees Celsius under four different series of conditions. It shows the pH level over the maintained several days. The bottom graph line corresponds to the Ni bath control solution (also shown in the figure description), which corresponds to the solution not exposed to the nickel anode (ie, the nickel anode in the flask). There was no). The figure shows that the pH level was maintained at a level of approximately 4.0 throughout the test period. Similarly, when the solution was subjected to air sparging again in the absence of the nickel anode, the pH remained constant at approximately 4.0. However, the two stagnant graph lines in Figure 1B correspond to the solution stored with the nickel anode (see figure description) (Vale). Americas S round anode), the pH level rises steadily in the presence of the nickel anode, exceeding pH 4.5 after about 7 days in each case, and rising even more rapidly when the bath solution is agitated. Is shown. The conclusion is that the presence of the nickel anode in the electroplating tank is the main cause of the pH increase seen during the rest period, and exposure to air and oxygen gas itself is not the cause of the fluctuation. The effect of stirring the electroplating solution should also be noted in that it observed rapid pH fluctuations. This is because, in particular, depending on the electroplating system, the electrolyte may still flow into the anode and cathode chambers of the device even if there is no charge transferred to the wafer during the rest period (when nickel is not plated) -electroplating. Due to possible inconveniences associated with stopping the flow of electrolytes when the system is dormant-the flow that progresses during such a dormancy is (to some extent) mimicked by the agitation performed in this particular experiment. Because it can be done.

The effect of nickel anode composition and dissolved oxygen levels on pH fluctuations is shown in Figure 1C, again in this figure again with some nickel sulfamate Ni200 electroplating bath solutions in Ellenmeier flasks under various conditions. It shows the pH level for several days maintained at 55 degrees Celsius. The three graph lines in the figure (see figure description) are (i) exposed to high-purity nickel anodes, air-sparged plating solutions, and (ii) sulfur-active nickel anodes (S-rounds). Corresponds to a plating solution that has been sparged with air, and (iii) a plating solution that has been exposed to a sulfur-active nickel anode (S round) and sparged with nitrogen. Solution (ii) showed a pH increase from 4.1 to 4.7 over 10 days, while solutions (i) and (iii) showed only a slight pH increase from 4.25 to 4.4. Approximately 0.022 to 0.30% sulfur is added to the sulfur-active nickel anode (S round), which is specifically done to prevent the formation of oxides, which effectively "activates" the anode. Note that "sulfur" -sulfur may refer to an anti-passivation additive-which improves dissolution properties. This fact is supported by the fact that the pH was further increased by the solution exposed to the anode containing these activated sulfurs. The conclusion drawn as a result of the above experiments is that the presence of the activated nickel anode and the presence of dissolved oxygen combine to result in the pH increase seen in the resting nickel sulfamate electroplating bath. It is clear that the activated nickel anode cannot be removed because an activated nickel anode is required in advance for effective nickel electroplating operations. Therefore, what we have pursued as a result of these experiments is methods and devices for minimizing or eliminating the dissolved oxygen concentration in the bath in order to alleviate the problem of pH fluctuation during rest.

Possible chemical mechanisms for pH fluctuations exhibited by these dormant nickel sulfamate electroplating baths include oxidation of the nickel anode through the following reactions.

<maths num="1"><img file="JP6502628B2_D0001.tif" /></maths>

This may be a predominant mechanism for the consumption of free acid protons that leads to the observed pH fluctuations. The redox reaction (1) is a combination of two half-reactions, that is, the oxidation of the nickel anode shown in the reaction formula (2) and the reduction of the dissolved oxygen shown in the reaction formula (3).

<maths num="2"><img file="JP6502628B2_D0002.tif" /></maths>

<maths num="3"><img file="JP6502628B2_D0003.tif" /></maths>

The sum of the electrochemical potential shown next to the reaction formula (3) and twice the electrochemical potential shown next to the formula (2) is the electricity of the entire redox reaction shown next to the formula (1). Note that it is the chemical potential, which indicates that this reaction is electrochemically preferable. In addition, sulfur in the activated nickel anode lowers the potential, at which nickel dissolves in the bath, which increases the thermodynamic driving force shown in row Eq. (1).

Reaction equations (1), (2), and (3) appear to be the predominant mechanism for the consumption of free protons in the resting nickel sulfamate bath, but other mechanisms may be used alone or in combination. Is considered to contribute. For example, direct acid-induced corrosion (reduction of free protons, and oxidation of nickel),

<maths num="4"><img file="JP6502628B2_D0004.tif" /></maths>

However, it may consume free protons in the bath. Another possible mechanism is related to the fact that the nickel anode may and probably has one or more oxide or carbonized layers on its surface first. When such an oxide layer or carbonized layer comes into contact with the electrolyte, these layers are deetched and Ni²⁺And consume free protons. For example, the following reactions are likely to occur on the surface of an oxidized or carbonized nickel anode upon contact with an acidic electrolyte plating solution.

<maths num="5"><img file="JP6502628B2_D0005.tif" /></maths>

<maths num="6"><img file="JP6502628B2_D0006.tif" /></maths>

<maths num="7"><img file="JP6502628B2_D0007.tif" /></maths>

In addition to such pH-raising chemistries, which are supposed to occur in dormant nickel electroplating baths, as mentioned above, during charge transfer-ie during electroplating operations. A complementary chemical mechanism due to elevated pH is assumed. Such a mechanism is described in detail in U.S. Patent Application No. 13 / 706,296 filed on December 5, 2012, in the title of the invention "APPARATUSES AND METHODS FOR CONTROLLING PH IN ELECTROPLATING BATHS". The whole picture is incorporated herein by reference in practice. For example, as described in this document, nickel plating at the cathode reacts as shown in equation (8) and is not 100% kinematically effective, instead approximately 97-99. It seems that it is caused by the effect of%.

<maths num="8"><img file="JP6502628B2_D0008.tif" /></maths>

This is known to be achieved by consuming hydrogen ions by generating hydrogen gas, as shown in equation (9), which explains the remaining 1-3% acid consumption. I think that the. Both of these mechanisms result in net consumption of hydrogen ions, which leads to the aforementioned pH increase over time.

<maths num="9"><img file="JP6502628B2_D0009.tif" /></maths>

One possible way to deal with the consumption of hydrogen ions is by adding sulfamic acid to the bath on a regular basis. FIG. 2 shows the amount of sulfamic acid required to return the bath, which consists of 75 g / L of nickel sulfamate and 30 g / L of boric acid, from a pH above 4 to pH 4. As can be seen from FIG. 2, the amount of moderate to strong acid with a pKa of less than 4 needed to be significantly increased as the solution moved away from the target pH of 4. Nevertheless, as this figure suggests, in principle, the pH of the bath is adjusted by predicting, calculating, measuring and regularly adding sulfamic acid for neutralization. It is possible to mitigate the rise in pH.

However, in practice, the regular addition of sulfamic acid causes many inconveniences, complications and problems. This occurs to a large extent due to the short residual period of sulfamic acid in solution due to hydrolysis to form ammonium hydrogensulfate over time.

<maths num="10"><img file="JP6502628B2_D0010.tif" /></maths>

Since the aqueous sulfamic acid solution is decomposed relatively rapidly by the reaction shown in equation (10) above, the solution must usually be prepared quickly from its solid form before use. If not prepared immediately, as is often the case with preparation, the actual concentration of sulfamic acid in aqueous solution is constantly decreasing, and it is expected that control by automatic addition will be very difficult. On the other hand, solid sulfamic acid is stable and not hygroscopic, but handling and addition with solid reagents is undesirable and inconvenient. However, in any case, whether the solid form of sulfamic acid or the aqueous form of sulfamic acid is used, the anion concentration of sulfamic acid is suitable for the plating bath when it is repeatedly added to alleviate the pH fluctuation. It rises beyond the above range, and eventually it becomes necessary to replace part or all of the bath by using an injection method or the like. Therefore, for all these reasons, adding sulfamic acid to control pH fluctuations from a realistic point of view is extremely problematic and inconvenient, even at best.

Therefore, it is important to keep the pH level of the nickel electroplating bath within a certain suitable pH range, thus mitigating and / or mitigating and / or reducing the pH fluctuations caused by the presence of oxygen dissolved in the bath. Methods and devices have been developed to minimize and / or prevent such methods and devices are disclosed herein. In some embodiments, the preferred pH range is from about pH 3.0 to pH 5.0, or more specifically from about pH 3.5 to pH 4.5, and more specifically from about pH 3.8 to pH 4.2. It may be there. These methods and devices typically operate by removing the dissolved oxygen gas from the electroplating solution before the dissolved oxygen gas enters the anode chamber.

In addition, these methods of preventing or reducing pH fluctuations may be implemented in the context of methods of electroplating one or more semiconductor substrates. Similarly, these devices that prevent or reduce pH fluctuations may be implemented in the background of a system and / or device for electroplating one or more semiconductor substrates. Therefore, various electroplating systems, devices, methods, operations, etc. will be described with reference to FIGS. 3A to 3D.

In some embodiments, the electroplating apparatus and related methods may include devices and methods for controlling the hydrodynamics of the electrolyte during plating so that a highly uniform plating layer is obtained. In certain embodiments, the disclosed embodiments are a collision flow (a flow that faces the surface of the workpiece or is perpendicular to the surface of the workpiece) and a shear flow (sometimes referred to as "cross flow", that is, the workpiece. Use a method and device that produces a combination of (flow at a velocity traveling parallel to the surface of the).

So, for example, one embodiment is an electroplating apparatus with the following features: (a) configured to include the electrolyte and anode while electroplating the metal onto a substantially flat substrate. Plating chamber; (b) Substrate holder configured to hold a substantially flat substrate so that the plated surface of the substrate is separated from the anode during electroplating; (c) Substantially on the plated surface of the substrate during electroplating A channeled ionic resistance member or plate (sometimes referred to herein as CIRP or flow embodied plate) with a substrate-facing surface parallel to and away from this plating surface, and a plurality of non-plates. Ion resistance members with channels that have communicating channels that allow electrolytes to be transferred to the member during electroplating; and (d) shear forces (crossflow) to the electrolyte flowing through the plating surface of the substrate. ) And / or a mechanism for applying. Wafers are substantially flat, but usually also have one or more microgrooves, which may have one or more portions of the surface that are shielded from exposure to electrolytes. In various embodiments, the apparatus also comprises a mechanism for rotating the substrate and / or the ion resistance member with the channel while the electrolyte in the electroplating tank flows in the direction of the plating surface of the substrate.

In certain embodiments, the mechanism for applying crossflow is, for example, an inlet with means for appropriately guiding and distributing the flow to or near the periphery of a channeled ion resistance member. The inlet guides the cross-flow catholyte along the substrate-facing surface of the ion resistance member with the channel. The inlet is azimuthally asymmetric, partially flows around the channeled ion resistance member, has one or more gaps, and is substantially flat with the channeled ion resistance member during electroplating. A cross-flow injection manifold is defined between the two substrates. Other members are optionally provided to function at the same time as the cross-flow injection manifold. They may include a shower head that distributes the flow of the cross-flow injection and a cross-flow confinement ring or flow divider, which will be further described below in conjunction with the drawings.

In some embodiments, the device is at least about 3 cm / sec with the electrolyte flowing in the direction towards or perpendicular to the plating surface of the substrate and out of the holes in the channeled ion resistance member during electroplating. It is configured to produce an average flow velocity (eg, at least about 5 cm / sec or at least about 10 cm / sec). In some embodiments, the device aligns the center point of the plated surface of the substrate to about 3 cm / sec or more (eg, about 5 cm / sec or more, about 10 cm / sec or more, about 15 cm / sec or more, or about 20 cm / sec. The above) is configured to operate under conditions that cause an average speed across the electrolyte. These flow rates (ie, the flow out of the holes in the ion resistance member and the flow rate from end to end of the plated surface of the substrate) are, in some embodiments, electricity using the entire electrolyte at a flow rate of about 20 L / min. A plating tank and a substrate with a diameter of approximately 12 inches are suitable. The embodiments herein may be implemented on substrates of various sizes. In some cases, the diameter of the substrate is about 200 mm, about 300 mm, or about 450 mm. Moreover, embodiments herein may be implemented at a wide variety of overall flow rates. In certain implementations, the overall electrolyte flow rate is about 1-60 L / min, about 6-60 L / min, about 5-25 L / min, or about 15-25 L / min. The flow rate reached during plating may be limited by certain hardware constraints, such as the size and dose of the pump used. One of ordinary skill in the art will appreciate that the flow rates listed herein can be even higher when the disclosure technique is implemented with larger pumps.

Note that in some embodiments, the electroplating apparatus has separate anode and cathode chambers, each with a different electrolyte composition, electrolyte circulation loop, and / or hydrodynamics. Ion permeable membranes may be used to prevent direct convective transfer of one or more components between the chambers (movement of the mass by flow) and to maintain the desired distance between the chambers. This membrane can block the flow of large amounts of electrolytes and eliminate the transfer of certain species such as organic additives while allowing the transfer of ions such as cations. In some embodiments, the membrane comprises a DuPont NAFION® or related ion-selective polymer. In other cases, the membrane does not contain an ion exchange material and instead contains a porous material. By convention, the electrolyte in the cathode chamber is called the "cathode solution" and the electrolyte in the anode chamber is called the "anode solution". The anolyte and catholyte often differ in composition, the anolyte contains little or no plating additives (eg, accelerators, inhibitors, and / or levelers), and the catholyte contains significant amounts of such additives. It is contained in the concentration of. The concentrations of metal ions and acids are also often different between the two chambers. An example of an electroplating device with a separate anode chamber is U.S. Pat. No. 6,527,920 filed November 3, 2000 [Agent Reference Number NOVLP007]; U.S. Patent No. 27 filed August 27, 2002. It is described in US Pat. No. 6,821,407 [Agent Reference No. NOVLP048] and US Pat. No. 8,262,871 [Agent Reference Number NOVLP308] filed on December 17, 2009. Incorporate the whole picture.

In some embodiments, the anode membrane does not need to contain an ion exchange material. In some examples, the membrane is made of a porous material such as a polyether sulfone from Koch Membrane, Wilmington, Mass., USA. This film type is most notably applicable to applications of inert anodes such as tin-silver plating and gold plating, but may also be used to applications of soluble anodes such as nickel plating.

In some embodiments, and as more fully described in other paragraphs herein, the cathode fluid is injected into the manifold region and the electrolyte is fed, accumulated and then dispensed within this region. It travels directly towards the wafer surface virtually uniformly through the various non-communication channels of CIRP.

In the following discussion, when referring to the upper and lower features (or similar term, upper and lower features, etc.) or members of the disclosed embodiments, the terms top and bottom are used merely for convenience. It merely represents a reference example or implementation of one framework of the present invention. Other configurations are possible, for example, the top and bottom components are reversed relative to gravity, and / or the top and bottom components are left and right or right and left components. Something like that.

Some aspects described herein may be used in various types of plating equipment, but for simplicity and clarity, most examples relate to wafer face-down "jet" plating equipment. In such devices, the workpieces for plating (usually the semiconductor wafers of the examples shown herein) are generally oriented substantially horizontally (which may be part of the plating process or the entire plating process). (May change several degrees from the exact horizontal), which may be fed to rotate during plating, producing an overall vertical and upward electrolyte convection pattern. Incorporating a mass of collision current from the center of the wafer to the edge and rotating the wafer at the edge rather than the center at a higher inherent angular velocity creates a radial increasing velocity of shear (parallel to the wafer) flow. An example of a member of a jet plating tank / equipment is Novellus in San Jose, California, USA. It is a Sabre (registered trademark) electroplating system manufactured by Systems and sold by the company. The jet electroplating system also includes, for example, U.S. Patent Application No. 6,800,187 [Agent Reference Number NOVLP020] filed on August 10, 2001 and U.S. Patent Application No. 8,308,931 [Agent] filed on November 7, 2008. Reference number NOVLP299], which is incorporated herein by reference in its entirety.

The substrate to be plated is generally flat or substantially flat. As used herein, substrates with features such as grooves, tubes, photoresist patterns, etc. are considered to be substantially flat. These features are often of fine scale, but this is not always the case. In many embodiments, one or more portions on the substrate surface may be shielded from exposure to electrolytes.

The following description of FIGS. 3A and 3B provides an overall non-limiting background to aid in understanding the devices and methods described herein. FIG. 3A is a perspective view of a device 100 that holds and positions the wafer for electrochemical processing of the semiconductor wafer. Device 100 includes components that engage the wafer (sometimes referred to herein as "clamshell" components). The actual clamshell includes a cup portion 102 and a conical portion 103, both of which can apply pressure between the wafer and the seal, thereby fixing the wafer in the cup portion.

The cup portion 102 is supported by the support column 104, and the support column is connected to the upper plate 105. This assembly (102-105), in total, the assembly 101 is driven by the motor 107 via the spindle 106. The motor 107 is mounted on the mounting bracket 109. Spindle 106 transfers torque to the wafer (not shown in this figure) to rotate it during plating. An air cylinder (not shown) inside the spindle 106 also provides a normal force between the cup and the cone 103 to create a seal between the wafer housed in the cup and the sealing member (lip seal). .. In considering this, the assembly including the components 102 to 109 is collectively referred to as a wafer holder 111. However, it should be noted that the concept of "wafer holder" as a whole extends to various combinations and subcombinations of components that engage and move and position the wafer.

A tilted assembly comprising a first plate 115, wherein the first plate is slidably connected to the second plate 117, is coupled to the mounting bracket 109. The drive cylinder 113 is connected to both the plate 115 and the plate 117 by rotary joints 119 and 121, respectively. Therefore, the drive cylinder 113 provides the force to slide the plate 115 (and thus the wafer holder 111) from end to end of the plate 117. The distal end of the wafer holder 111 (ie, the mounting bracket 109) moves along a curved path (not shown) that defines the contact area between the plates 115 and 117, thereby with the proximal end of the wafer holder 111 (ie, the cup portion). The assembly with the cone) tilts with respect to the de facto axis. This allows the wafer to be placed diagonally into the plating bath.

The entire apparatus 100 is lifted vertically either upwards or downwards to immerse the proximal end of wafer holder 111 in the plating solution via another actuator (not shown). Therefore, the mechanism for positioning the two components is a vertical motion along the trajectory perpendicular to the electrolyte and a tilt motion that deflects the wafer from a horizontal orientation (parallel to the plane of the electrolyte) (the ability to immerse the wafer diagonally). And provide both. A detailed description of this athletic performance and the hardware of its associated device 100 was filed on May 31, 2001 and issued on April 22, 2003, US Pat. No. 6,551,487 [Agent Reference Number NOVLP022]. ], Which is incorporated herein by reference in its entirety.

It should be noted that device 100 is typically used with certain plating tanks that have an anode (eg, a nickel anode or a non-metallic inert anode) and a plating chamber that houses the electrolyte. The plating tank may also include a pipe or pipe connection for circulating the electrolyte in the plating tank-and to the workpiece to be plated. Membranes or other isolates designed to maintain the chemistry of different electrolytes in the anode and cathode compartments may also be provided. In one embodiment, one membrane is used to define the anode chamber, which contains an electrolyte that is substantially free of inhibitors, accelerators, or other organic plating additives. Alternatively, in another embodiment, the inorganic plating compositions of the anolyte and catholyte are substantially different. Any mechanism may be provided to transfer the anolyte to the catholyte or main plating bath (eg, by direct pumping including a valve, or to an overflow vessel).

The following description describes in more detail the assembly of the clamshell cup and cone. FIG. 3B depicts a portion 101 of assembly 100 with a conical portion 103 and a cup portion 102 in cross-sectional form. It should be noted that this figure does not imply an exact depiction of the assembly made up of the cup and cone, but rather a stylized depiction for consideration. The cup portion 102 is supported by the upper plate 105 via the support column 104, and the support column is attached via the screw 108. Overall, the cup portion 102 serves as a support on which the wafer 145 retains. The cup portion has an opening through which the electrolyte coming from the plating tank can come into contact with the wafer. Note that the wafer 145 has a front surface 142, where the front surface is plated. The peripheral edge of the wafer 145 remains on the cup portion 102. The conical portion 103 presses against the back surface of the wafer to hold the wafer in place during plating.

To mount the wafer in 101, lift the cone 103 from the illustrated position via the spindle 106 until the cone 103 touches the top plate 105. From this position, a gap is created between the cup portion and the conical portion, and the wafer 145 can be inserted into this gap, and thus the wafer can be mounted in the cup portion. Next, the conical portion 103 is lowered to engage the wafer with the peripheral edge of the cup portion 102 as shown, and a series of electrical contact portions radially beyond the lip seal 143 along the outer circumference of the wafer. (Not shown in Fig. 3B).

The spindle 106 transmits both the normal force for engaging the cone 103 with the wafer 145 and the torque for rotating the assembly 101. These transmitted forces are shown by arrows in Figure 3B. Note that the wafer plating is usually done while the wafer is rotating (as indicated by the dashed arrow above Figure 3B).

The cup portion 102 has a compressible lip seal 143, which forms a fluid airtight seal as the conical portion 103 engages with the wafer 145. The normal force from the cone and wafer compresses the lip seal 143 to form a fluid-tight seal. The lip seal prevents the electrolyte from contacting the back surface of the wafer 145 (when contaminants such as nickel ions can enter directly into the silicon) and also contacts the perishable components of device 101. To prevent. There may be a seal located between the interface of the cup portion and the wafer, which forms a fluid airtight seal to further protect the back surface (not shown) of the wafer 145.

The conical portion 103 also includes a seal 149. As shown, the seal 149 is located near the edge of the conical portion 103 when engaged and in the upper region of the cup portion. This also protects the back of the wafer 145 from any electrolyte that may enter the clamshell from above the cup. The seal 149 may be fixed to a conical or cup portion and may be a single seal or a seal consisting of a plurality of components.

When plating begins, the conical portion 103 rises above the cup portion 102 and the wafer 145 is introduced into the assembly 102. When the wafer is first introduced into the cup 102-usually by a robotic arm-the front surface 142 of the wafer rests lightly on the lip seal 143. During plating, assembly 101 rotates to help achieve uniform plating. In subsequent drawings, assembly 101 is depicted in a simpler form in association with components for controlling the hydrodynamics of the electrolyte on the plating surface 142 of the wafer being plated. Therefore, the following is an overview of mass transfer and fluid shearing in workpieces.

FIG. 3C schematically illustrates an embodiment of an electroplating tank having an anode chamber and a cathode chamber according to the specific embodiments described herein. It should be noted that the embodiment shown in FIG. 3C implements a particular technique that can be used to facilitate end-to-end crossflow of the surface of the substrate to be plated, which was filed on May 13, 2013. As described in US Pat. No. 13,893,242, the title of the invention, "CROSS FLOW MANIFOLD FOR ELECTROPLATING APPARATUS", the entire contents of which are incorporated herein by reference. As fully described by this prior application, in some embodiments, the electrolyte inflow port is alone or described in this document, a flow reification plate, a cross-flow manifold, and /. Alternatively, it is configured to assist cross-flow in combination with a flow divider.

For example, the electroplating tank schematically shown in FIG. 3C comprises an electrolyte inlet configured to facilitate cross-flow with an assembly of a flow embodying plate and a flow divider. Specifically, FIG. 3C is a cross-sectional view of the components of the plating apparatus 700 for plating nickel on the wafer 145, the wafer being held, positioned and rotated by the wafer holder 101. The device 700 includes an electroplating tank 755, which is a two-chamber tank, which has an anode 760, an anode chamber 750 with an anode solution, and a cathode chamber 760. The anode chamber 750 and the cathode chamber 760 are separated by a cationic film 740 supported by a support member 735. The electroplating apparatus 700 includes a flow reification plate 710 as described herein. A flow divider (sometimes referred to as a confinement ring) 725 is located on top of the flow reification plate 710 to assist in producing the transverse shear flow described herein. The cathodic solution is introduced into the cathodic chamber (above the membrane 740) via the inflow port 715. The cathodic liquid causes a collision flow from the inflow port 715 through the flow plate 710 described herein to the plated surface of the wafer 145. In addition to the cathodic inlet 715, a complementary inlet 710a introduces the cathode fluid at its outlet at a location far from the holes or gaps in the flow divider 725. In this example, the outlet of the inflow port 710a is formed as a channel in the flow reification plate 710. The functional result is that the cathodic solution is introduced directly into the simulated chamber formed between the flow plate and the plating surface of the wafer, facilitating cross-flow flow from end to end of the wafer surface. The vector that flows from end to end of the wafer (and flow plate 710) is normalized.

The electroplating tank may be provided as one or more modules of the electroplating system and may also benefit from the methods and devices disclosed herein to reduce or prevent pH fluctuations. For example, FIG. 3D schematically illustrates an electroplating system 307 that may include multiple electroplating modules, in this case three separate modules 309, 311 and 313. As described more fully below, each electroplating module typically holds the anode in the electroplating process and a tank for the electroplating solution, and holds the wafer in the electroplating solution to rotate the wafer during electroplating. It is equipped with a wafer holder for plating. The electroplating system 307 shown in Figure 3D further comprises three separate electrofill post-treatment modules (PEMs) 315, 317 and 319. Depending on the embodiment, they can each be used to perform any of the following functions: Edge Slope Removal (EBR), Back Etching, and 1 of Modules 309, 311, and 313. The wafer is pickled after being electrically filled with the module. It should be noted that the electrofilling post-treatment module (PEM) that performs edge slope removal (EBR) is instead simply referred to herein as the EBR module. The electroplating system 307 may also include a chemical dilution module 321 and a central electrofilling bath 323. The central electrofill bath 323 may be a tank that holds a chemical solution used as an electroplating bath in the electrofill module. The electroplating system 307 may also include an addition system 333 that stores the chemical additives and transports them to the plating bath. If so, the chemical dilution module 321 can store and mix the chemicals used as the etchant in the electrofill post-treatment module. In some embodiments, the filtration / pumping unit 337 filters the plating solution towards the central bath 323 and delivers the plating solution to the electrofill module.

Finally, in some embodiments, the electronic unit 339 can serve as a system controller that provides the electronic and interface controls required to operate the electroplating system 307. A system controller typically comprises one or more storage devices and one or more processors configured to execute instructions so that the electroplating system can perform the intended processing operation. A machine-readable medium containing instructions for controlling processing operations according to the implementations described herein can be connected to the system controller. Unit 339 may include a power supply for the system.

In operation, a robot with a back-end robotic arm 325 can be used to select wafers from wafer cassettes such as cassettes 329A or 329B. The back-end robot arm 325 may be mounted on the wafer using a vacuum mounting machine or some other feasible mounting mechanism.

The front-end robot arm 340 can select one wafer from wafer cassettes such as cassette 329A or cassette 329B. Cassette 329A or 329B is a hoop (front opening unified It may be pod, FOUP). FOUP is a housing designed to securely and safely hold wafers in a controlled environment and to remove wafers for processing or measurement using machines with appropriate load ports and robotic handling systems. .. The front-end robot arm 340 can hold the wafer using a vacuum mounting machine or some other mounting mechanism. The front-end robot arm 340 can interact with cassette 329A or 329B, transfer station 350, or aligner 331. The back-end robot arm 325 can gain access to the wafer from the transfer station 350. The transfer station 350 may be a slot or position where the front-end robot arm 340 and the back-end robot arm 325 can reciprocate to move the wafer without approaching the aligner 331. However, in some implementations, the back-end robot arm 325 aligns the wafer with the aligner 331 to ensure that the wafer is properly placed on the back-end robot 325 and accurately transported to the electroplating module. Can be placed. The back-end robot arm 325 can also carry wafers to one of the electrical filling modules 309, 311 or 313, or to one of the three electrical filling post-processing modules 315, 317, and 319.

Using the aligner module 331, place the wafer correctly on the back-end robot arm 325 and electroplating modules 309, 311 or 313, or EBR modules 315, 317, and 319 (assuming these PEMs perform EBR). In situations where ensuring accurate transport to either, the back-end robotic arm 325 transfers the wafer to the aligner module 331. In some embodiments, the aligner module 331 comprises an placement arm, and the backend robot arm 325 presses the wafer against this placement arm. When the wafer is correctly placed with respect to the placement arm, the backend robot arm 325 moves to a preset position with respect to the placement arm. In another embodiment, the aligner module 331 centers the wafer so that the back-end robot arm 325 lifts the wafer from a new position. The back-end robotic arm 325 then reattaches to the wafer and transports the wafer to one of the electroplating modules 309, 311 or 313, or to the EBR modules 315, 317, and 319.

Thus, in the typical task of forming a metal layer on a wafer using electroplating system 307, the back-end robot arm 325 uses pre-electroplating to adjust the centering of the wafer to wafer cassette 329A. Or from 329B to aligner module 331, then to electroplating module 309, 311, or 313 for electroplating, then back to aligner module 331 for pre-EBR centering adjustment, then edge slope. Return to EBR module 315, 317, or 319 to remove. Of course, in some embodiments, the centering / placement step may be omitted if wafer rearrangement is not normally required.

As mentioned above, for electroplating work, the wafer is mounted on a wafer holder such as a clam shell, and electroplating is performed in one of the tanks of the electroplating modules 309, 311 or 313 where electroplating is performed. It may be necessary to lower the clamshell in the bath. Also, as mentioned above, this tank usually contains an anode that serves as a source of metal to be plated (the anode can be far away), as well as optional chemistry from the addition system 333. It also contains an electroplating bath solution that is often supplied from the central electrofill bath 323 along with the additives. The EBR operation after the electroplating operation usually requires the removal of unwanted electroplated metal from the edge slope region and, in some cases, the back surface of the wafer by applying the etchant supplied by the chemical dilution module 321. Is. After EBR, the wafer is usually washed, shaken and dried. Finally, after the post-filling process, the process is complete and the backend robotic arm 325 can retrieve the wafer from the EBR module and return the wafer to cassette 329A or 329B. From there, cassettes 329A or 329B may be provided to other semiconductor wafer processing systems, such as chemical mechanical polishing systems.

It should be noted again that the devices and devices disclosed herein to prevent, reduce or minimize pH fluctuations may be implemented within the background of the electroplating tanks, modules, and systems described so far. .. Similarly, the methods for preventing, reducing or minimizing pH fluctuations disclosed herein are the background of electroplating methods performed in any of the electroplating tanks, modules, and systems described so far. Please note again that it may be carried out within.

[Electroplating system to reduce pH fluctuation]

Accordingly, disclosed herein is an electroplating system for electroplating a metal onto a semiconductor substrate, a method or device for reducing or preventing pH fluctuations in one or more electroplating tanks. It is an electroplating system using. As explained in detail above, the presence of oxygen in the electroplating solution in the electroplating tank, without limitation to a particular theory, during the electroplating operation and during the rest period (from the electroplating operation to the next It is thought that the pH will rise even during the period until the electroplating work), which causes the quality of the electroplated metal layer to deteriorate. Therefore, as disclosed herein, the electroplating system may include an oxygen scavenger for reducing the oxygen concentration of the electrolyte solution used in the electroplating operation. In some embodiments, the oxygen scavenger can remove oxygen from the electroplating solution as it flows into one or more electroplating tanks of the electroplating system.

For example, FIG. 4A schematically illustrates an electroplating system 400, in which the electroplating system is consistent with the particular embodiment disclosed herein, as the electroplating solution flows into the electroplating tank 410 of the system. , An oxygen scavenger 480 is used to reduce the oxygen concentration in the electroplating solution. In this embodiment, the electroplating tank 410 comprises an anode chamber 420 and a cathode chamber 430, both chambers separated by a porous membrane 440, which membrane is similar to that shown and described in FIG. 3C above. Is. The anode chamber is, of course, for holding one or more anodeseg, anode 422 in FIG. 4A and anode 460 in FIG. 3C, during electroplating operations. If it is an electroplating system for electroplating nickel on a semiconductor substrate, of course, there is a nickel anode in the anode chamber during electroplating. The cathode chamber 430 surrounds a place in the electroplating tank 410, where the surface of the substrate to be electroplated on is held by the wafer holder at the same time as it comes into contact with the electrolyte solution and is made of metal on the semiconductor substrate. Precipitation occurs. Specifically, with reference to FIG. 3C, in the cathode chamber 740 in the electroplating tank 755, the substrate 145 comes into contact with the electrolyte solution while being held by the wafer holder 101. Note that in some embodiments, the electroplating system 400 may be configured to expose the electrolyte solution to the atmosphere while electroplating nickel on the substrate. In this type of embodiment, the presence of the oxygen scavenger 480 is even more important, as the electrolyte solution may be absorbing oxygen from the atmosphere during the electroplating operation.

The electrolyte solution circulating in the anode chamber is generally called the anode solution, and the electrolyte solution circulating in the cathode chamber is generally called the cathode solution, but these two solutions are substantially different depending on the embodiment. It may have the same composition or different compositions. Anode fluid and cathode fluid can be circulated in and out of the anode and cathode chambers, respectively, by a fluid conduit, pump, and / or valve system. Listed below are some of the many possible configurations. The volume and flow rate of the anode fluid entering the anode chamber may be substantially the same as the volume and flow rate of the cathode fluid entering the cathode chamber, but in some embodiments the flow rates may be different. For example, in some configurations, if the flow rate of the anolyte entering the anode chamber is small (compared to the flow rate of the cathode fluid entering the cathode chamber), there is a demand for an oxygen scavenger operating on the anolyte. May decrease. For example, in one embodiment, the flow rate of the cathode fluid flowing into the cathode chamber may be about 12 to 48 liters / minute, whereas the flow rate of the anode fluid flowing into the anode chamber is about 1 to 4 liters / minute. It's okay. For 300 mm wafers, the overall flow rate of the electrolyte (including the anolyte and catholyte) flowing into the electroplating tank is about 3 to 30 liters / minute, or more specifically about 6 to 24 liters / minute. It's okay. For 450 mm wafers, the overall flow rate of the electrolyte (including the anolyte and catholyte) flowing into the electroplating tank is about 7 to 68 liters / minute, or more specifically about 14 to 54 liters / minute. It's okay.

If the flow rate to the anode chamber is small, it may be possible to achieve a similar reduction in oxygen concentration using a smaller and less expensive oxygen scavenger. Instead of doing this, in some configurations, a low flow of anolyte may result in a reduction in oxygen concentration in the anolyte for a given oxygen scavenger, thereby removing specific oxygen. Less demand on the device.

In some embodiments, the anode fluid in the anode chamber and the cathode fluid in the cathode chamber may be separated by a porous separator 440, regardless of the composition and flow rate of each of the chambers. , Ion currents are allowed to pass during electroplating, but the passage of electrolyte solutions in the anode and cathode chambers 420 and 430 is blocked (at least to a certain extent). In other words, this separator prevents the anolyte and catholyte from mixing, at least to a certain extent. This can be important if the anolyte and catholyte have different compositions, but otherwise the porous separator 440 is a particulate matter coming from the anode chamber-probably generated by the decomposition of the anode-in the cathode chamber. It can be important to prevent (at least to some extent) the particles from coming into contact with and contaminating the surface of the electroplated substrate in the cathode chamber. With this in mind, the anode chamber can be viewed in a broad sense as a region of the electroplating tank containing one or more metal anodes, which is another area of the electroplating tank that holds the wafer. Separated from one region-that is, the cathode chamber-through the barrier, the barrier is designed to prevent (at least to some extent) the contamination from one or more metal anodes from reaching the cathode chamber.

However, in some embodiments, the anode chamber is a complementary barrier configured or designed to prevent particles generated at the anode from contaminating the electroplating tank or other areas of the anode chamber itself. It should also be noted that is included. In some cases, this may be to prevent the porous separator 440 from being filled with or excessively overflowing particulate matter coming from the anode. Therefore, in some embodiments, a bag may be used to enclose the anode and trap the generated particles-this is often referred to in the prior art as "bagging the anode". In other embodiments, a complementary membrane or filter, or in a broader sense, another porous separator, is placed very close to the anode in the anode chamber to identify particles generated by the anode to a realistic extent. be able to.

More importantly, perhaps in some embodiments, the porous separator 440 can maintain the anode chamber 420 and the cathode chamber 430 at different oxygen concentrations. This can be important, for example, if the oxygen scavenger only removes oxygen carried from the electrolyte solution to the anode chamber-ie, oxygen from the anolyte. An electroplating system with a loop through which the electrolyte solution is thus designed is described in detail below, for example with respect to the oxygen scavenger 480 of FIG. 4B. Depending on the embodiment, the porous separator may be an ion exchange membrane, or in some embodiments, the porous separator may be a porous membrane with substantially no ion exchange sites.

The oxygen scavenger 480 (used to reduce the concentration of oxygen in the electrolyte solution as it flows into the electroplating tank 410), in some embodiments, particularly oxygen in the electrolyte solution flowing into the anode chamber 420. It can function to reduce the concentration. In other embodiments, the oxygen scavenger may be used to reduce the oxygen concentration in the electrolyte solution flowing into both the anode and cathode chambers. Further, while the oxygen reduction may occur during the electroplating operation, the oxygen scavenger 480 may operate during a downtime when the system is not performing any electroplating operation. Therefore, in some embodiments, the oxygen scavenger may be configured to reduce the oxygen concentration in the electrolyte solution flowing into the anode chamber during some or all rest periods.

Note that in some electroplating systems, when the electroplating system is not electroplating, the electrolyte solution continues to flow into the anode chamber during some or all pauses. Moreover, although perhaps favorable to the overall process flow and throughput of electroplating, such electrolyte circulation actually increases the hydrogen ion consumption rate on the surface of the nickel anode, and as mentioned above, the observed pH. It should also be noted that it may be exacerbating what appears to be the dominant reaction mechanism behind the fluctuations. In particular, with respect to FIG. 1B, it was noted above that the effect of stirring the flask containing the nickel anode round in the electroplating solution would dramatically increase the observed increase in pH rate. Therefore, circulating the electrolyte solution in the anode chamber may lead to an increase in pH even during non-electroplating, and therefore the electrolyte solution in the anode chamber during rest. Circulating electroplating systems can often derive even greater advantages from the oxygen reduction methods disclosed herein. Therefore, in some embodiments, the oxygen concentration in the electrolyte solution flowing into the anode chamber during some or all of the rest period is clearly defined by the pH of the electrolyte solution when in contact with the nickel anode during the rest period. The oxygen scavenger may be configured to lower the level so that it does not rise.

Various types of oxygen scavengers may be used depending on the embodiment. For example, one way to reduce the oxygen concentration in an electrolyte solution is to sparg the electrolyte solution. Sparging is a technique that involves using a liquid to foam a chemically inert gas to remove the dissolved gas from the liquid. The electrolyte solution may be sparged with, for example, helium, nitrogen, argon, etc. to replace the dissolved oxygen gas. Thus, in some embodiments, the oxygen scavenger of the electroplating system may or may be a device for sparging the electrolyte solution with a substantially oxygen-free gas.

Another type of oxygen scavenger that may be included in electroplating systems is the deaerator. A discussion of degassing devices and various degassing techniques is incorporated herein by reference to US Patent Application No. 12 / 684,792, filed January 8, 2010, with reference to this document. It should be noted that the deaerator may be referred to as a contactor and the terms used herein are interchangeable. In some embodiments, the deaerator may be a membrane contact deaerator, such that one or more membranes may be used in combination with one or more vacuum pumps to reduce the oxygen concentration in the electrolyte solution. Can function. Examples of commercially available membrane contact deaerators include Liquid-Cel® from Membrana (Charlotte, NY, USA) and Super from Membrana. These include Phobic membrane contactors and pHasor® from Entegris, Chaska, Minnesota, USA. In general, these membrane contact degassing devices work by applying a vacuum to the surface of the degassed fluid, essentially sucking the dissolved gas from the fluid. The presence of one or more membranes increases the exposed surface of the degassed fluid, which increases the exposure to the vacuum environment, thus increasing the effectiveness of the degassing action. Therefore, the rate at which the dissolved gas is removed from the electrolyte solution using the membrane contact degassing device is determined, for example, by the flow rate of the plating solution, the exposed area and properties of the semi-permeable membrane sandwiched between the vacuum applied to the degassing device, and so on. It may also depend on the strength of the applied vacuum. Normal membranes used in membrane contact deaerators allow molecular gas to flow, but do not allow larger molecules or solutions that cannot wet the membrane.

In some embodiments, applying fluid pressure to the fluid inlet of the deaerator can facilitate oxygen removal. For example, in the embodiment shown in FIG. 3A, a pump 460 is used upstream of the same fluid loop as the oxygen scavenger 480 (the fluid loop is further detailed below) to bring the electroplating solution to the fluid inlet of the oxygen scavenger. Drive. Therefore, controlling the hydrodynamics of the electrolyte solution flowing through a flow loop with an oxygen scavenger via a pump or other mechanism can help achieve the desired oxygen scavenging level of the degassing device. Of course, the presence of an oxygen scavenger in the flow loop may provide some advantage in the positioning of one or more pumps, but the flow loop for the electroplating solution, of course, circulates the fluid. There must be some form of pumping mechanism in place, whether or not it is for the sake of it.

One or more filters can be installed in the electrolyte flow loop upstream of the electroplating tank to prevent particles or bubbles from entering the electroplating tank and causing defects in the formation of the metal layer to be electroplated. In some embodiments, the filter 470 is placed in a flow loop just upstream of the electroplating tank 410, as shown in FIG. 4A, and the electroplating tank 410 is in the absence of at least some protection from the filter 470. May be free of intervening elements that could be exposed to the generation of particles or bubbles. In some embodiments, the filter may have a pore size of approximately 1 μm, and in certain such embodiments, aspirate 12-48 liters / min of electrolyte through the filter to remove particulate contaminants. Can be done.

In particular, since the pump often causes bubbles to be generated in the sucking fluid, the filter 470 downstream of the pump 460 can reduce or prevent the bubbles from entering the electroplating tank 410. Similarly, when the device for sparging the electrolyte solution is used as the oxygen scavenger 480, the filter 470 downstream of the oxygen scavenger 480 can help reduce or prevent the ingress of air bubbles, as well. If the oxygen eliminator 480 is a deaerator, such as a membrane contact deaerator, the filter 470 can assist in removing any particles generated from the fluid pressure applied to the membrane of the deaerator. In any case, no matter what specific (s) type (s) of oxygen scavengers (s) are used, the device is in the electrolyte flow loop (s). , It is preferable to install it somewhere where bubbles or particles are not introduced into the electroplating tank and are not particularly introduced into the cathode chamber.

Oxygen scavengers, whatever their type, reduce (or eliminate) the pH increase normally seen when the electrolyte solution comes into contact with the anode in the anode chamber of the electroplating tank to the desired level of dissolved oxygen concentration. ) Should have the ability to go down to level. Therefore, whether the oxygen scavenger is a degassing device, more specifically a membrane contact degassing device (or equipped with them), the electrolyte solution is sparged (eg, with a virtually oxygen-free gas). In some embodiments, whether it is a device for, or equipped with them, the oxygen scavenger may be configured to reduce the oxygen concentration in the electrolyte solution to a level of about 1 ppm or less. In certain such embodiments, the oxygen scavenger may be configured to reduce the oxygen concentration in the electrolyte solution to a level of about 0.5 ppm or less. However, it should also be noted and understood that in some embodiments, the oxygen concentration may be maintained at various different specific levels at different locations within the electroplating system. So, for example, in some embodiments, an oxygen scavenger configured to reduce the oxygen concentration in the electrolyte solution to some predetermined level is reduced to that level in the electroplating system region immediately downstream of the oxygen scavenger. It can, but does not necessarily have to be lowered across the electroplating system. In particular, the oxygen scavenger may be configured to achieve a given oxygen concentration (eg, 1 ppm or less, or 0.5 ppm or less) in the anode chamber downstream of the oxygen scavenger, but not necessarily in the cathode chamber. There is no. The fluid flow loops / paths to these chambers will be discussed in detail below.

In an electroplating system such as the system 400 shown in FIG. 4A, a bath tank 450 containing a reserve volume of electrolyte solution that can circulate in and out of the electroplating tank 410 through one or more flow loops may be used. .. Again, the configuration of a particular flow loop will be discussed in detail below, but FIG. 4A shows that there are two flow loops that fluidly connect the bath tank 450 to the electroplating tank 410. This is because there are two routes through which the circulating fluid can pass when moving from the bath tank 450 to the electroplating tank 410 and returning. The bath tank 450 may be installed outside the electroplating tank 410 as shown in FIG. 4A, or may be integrally formed with the physical structure forming the electroplating tank. Regardless of location, bath tanks typically have one or more fluid inlets that receive fluid from one or more fluid conduits (eg, pipes) and one or more fluid outlets that deliver fluid through one or more fluid conduits. Is equipped with. The fluid inlet may be downstream of the electroplating tank and the fluid outlet may be upstream of the electroplating tank. The bath tank can serve as a storage facility for the electrolyte fluid, but may provide other functions. In some embodiments, the bath tank 450 can provide, for example, the ability to remove oxygen or process other electrolyte fluids.

An electroplating system typically has at least one flow loop for the electrolyte solution to flow in and out of the electroplating chamber, and the various components discussed above-pumps, filters, oxygen scavengers, and the like. However, in some embodiments, the electroplating system can use multiple flow loops to guide the flow of electroplating solution between the electroplating tank and the various components, these flow loops. May employ a variety of different forms and fluid connection topologies.

For example, in an electroplating system with separate anode and cathode chambers, there may be a flow loop, referred to herein as an anode chamber recirculation loop, that fluidly connects the anode chambers to various components of the electroplating system. Similarly, there may be a cathode chamber recirculation loop that fluidly connects the cathode chamber to the various components of the electroplating system. In embodiments with such an anode chamber recirculation loop, the loop may be fluid connected to one or more fluid inlets and outlets of the anode chamber, anodicing the electrolyte solution while electroplating nickel on the substrate. It may be configured to flow into the room. Similarly, in an embodiment having a cathode chamber recirculation loop, the loop may be fluid connected to one or more fluid inlets and outlets of the cathode chamber, with the electrolyte solution during electroplating nickel on the substrate. It may be configured to flow into the cathode chamber. The anode chamber recirculation loop may be referred to herein simply as the "anode loop", and similarly, the cathode chamber recirculation loop may be referred to herein simply as the "cathode loop".

The anode loop and the cathode loop may share various fluid conduits in the electroplating system, except that the fluid flow through the path of the anode loop flows into the anode chamber but not into the cathode chamber. Similarly, it should be understood that the fluid flow through the path of the cathode loop is a point that flows into the cathode chamber but not into the anode chamber. An example is shown in Figure 4A. In this figure, the electroplating system 400 has separate anode chambers 420 and cathode chambers 430, both of which have an anode chamber recirculation loop 425 (or "anode loop") and a cathode chamber recirculation loop 435 (or "anode loop"). , "Cathode loop") are fluidly connected to the other components of the electroplating system 400, respectively. The direction of the fluid flowing through the flow loop and various fluid conduits is indicated by the arrows in the figure. As illustrated, the anode chamber recirculation loop 425 comprises fluid conduit sections 1001, 1011, 1012, and 1002, and the cathode chamber recirculation loop 435 comprises fluid conduit sections 1001, 1021, 1022, and 1002. Thus, although the two circulation loops share some fluid conduits (1001 and 1002), the anode chamber recirculation loop 425 still guides the fluid to the anode chamber and not to the cathode chamber, and the cathode chamber. It should be noted that the opposite is true for the recirculation loop 435. (For the sake of simplicity, the conduit 1001 is shown as a single line and represented by a single code, which is cut off at components 460, 470, and 480 in the figure, but-not required-three physical It is likely to be implemented as a simple pipe / conduit. It should be kept in mind that Figure 4A is schematic.) The cathode loop also has a flow manifold 437, which is the point where the electrolyte solution enters the cathode chamber 420. It is equipped. In some embodiments, the flow manifold 437 can assist in delivering the electrolyte solution into the cathode chamber 430, but its presence is, of course, not essential.

Therefore, in a system that has both an anode chamber circulation loop and a cathode chamber circulation loop, the various components of the electroplating system used to support the electroplating operation in the electroplating tank are the anode chamber circulation loops. It may be connected to the tank via either or both of the cathode chamber circulation loops. For example, the bath tank 450 of the electroplating system 400 of FIG. 4A is fluid connected to the electroplating tank 410 via both the anode loop 425 and the cathode loop 435, these loops as defined and detailed above. Is. From FIG. 4A, it can be seen that the fluid outlet of the bath tank is generally fluid connected to both the anode loop and the cathode loop through the fluid conduit 1001. Similarly, FIG. 4A schematically shows the fluid inlet of the bath tank 450 that is fluid connected to the conduit 1002 that carries the electrolyte fluid coming from both the anode loop 425 and the cathode loop 435. However, depending on the embodiment, the fluid inlet and outlet of the bath tank may instead be connected only to the anode loop and not to the cathode loop, or to only the cathode loop and not to the anode loop. ..

In electroplating systems that use one or more oxygen scavengers to deal with pH fluctuations, the location of one or more oxygen scavengers within the flow loop of the electroplating system can be an important point. For example, in FIG. 4A, the oxygen scavenger 480 is installed in both the anode loop 425 and the cathode loop 435 (respectively), upstream of both the anode chamber 420 and the cathode chamber 430 (respectively) but downstream of the bath tank 450. Has been done. Such an oxygen scavenger 480 is, as detailed above, a degassing device such as a contact membrane degassing device, or a device for sparging an electrolyte solution with a substantially oxygen-free gas, or both. May be equipped.

However, in other embodiments, the oxygen scavenger may be installed only in either the anode loop or the cathode loop. For example, FIG. 4B schematically shows an electroplating system 400 that closely resembles that shown in FIG. 4A. Similar to the system of FIG. 4A, the electroplating system 400 of FIG. 4B has an anode chamber 420 and a cathode chamber 430 separated by a porous film 440, a bath tank 450, a pump 460, a filter 470, an anode loop 425, a cathode loop 435, etc. It is equipped with an electroplating tank 410 having the above. However, in FIG. 4A, the oxygen scavenger 480 was installed in both the anode and the cathode loop, but in this case the oxygen scavenger 480 is installed only in the anode loop 425. As a result, the electrolyte solution that has passed through the oxygen scavenger 480 and is processed by the oxygen scavenger flows into the anode chamber 420 and not into the cathode chamber 430 (of course, the electrolyte solution back-diffuses throughout the porous separator 440). Ignore). Therefore, it can be said that the oxygen scavenger 480 of FIG. 4B is installed in the anode loop 425 upstream of the anode chamber 420 and downstream of the bath tank 450, but not in the cathode loop 435. Again, such an oxygen scavenger 480 is, as detailed above, a degassing device such as a contact membrane degassing device, or a device for sparging an electrolyte solution with a substantially oxygen-free gas. , Or both may be provided.

Installing the filter 470 for both the oxygen scavenger 480 and the anode loop 425 and the cathode loop 435 is another difference between the embodiment shown in FIG. 4A and the embodiment shown in FIG. 4B. is there. In both embodiments, the filter 470 is installed in both the anode loop 425 and the cathode loop 435, which uses a single filter element to allow the electrolyte solution to flow into the anode chamber 420 as well as the electrolyte solution to flow into the cathode chamber 430. Can both be filtered, which can be an advantage in some cases. So, for example, in Figure 4A, the filter 470 is located downstream of pump 460 and bath tank 450, but upstream of both anode chamber 420 and cathode chamber 430, so any particles or debris generated within tank 450 or from pump 460. , Both chambers can be protected from air bubbles.

However, in addition, in FIG. 4A, the filter 470 is also downstream of the oxygen scavenger 480, so that both the anode and cathode chambers are particles, debris and air bubbles generated from the oxygen scavenger (eg, detailed above). As such, it can be protected from air bubbles coming out of the sparging device, particulate matter coming out of the membrane of the deaerator, etc.). Therefore, the filter 470 can be described as being installed in the anode chamber recirculation loop 425 upstream of the anode chamber 420 and downstream of the oxygen scavenger 480 and the bath tank 450.

In contrast, in the embodiment schematically shown in FIG. 4B, the filter 470 remains installed in both loops, thus filtering the electrolyte flowing through both chambers, whereas the oxygen scavenger 480 is only in the anode loop 425. Since it is installed and in this position, it is downstream of filter 470. Therefore, in the embodiment of FIG. 4B, the electrolyte solution coming out of the oxygen scavenger 480 does not enjoy the advantage of being filtered by the filter 470 before entering the anode chamber 420. This may or may not be a problem, depending on the extent to which the oxygen scavenger 480 generates bubbles or particles in the electrolyte solution that requires filtration. If such filtration is required, or at least for some benefit, it is possible to install a complementary filter in the anode loop 425 downstream of the oxygen scavenger 480.

Nevertheless, installing the oxygen scavenger 480 only on the anode loop 425 may have other advantages, even though it may be located downstream of the filter 470 as shown in Figure 4B. is there. For example, the predominant mechanism behind pH fluctuations may be related to the degree of dissolved oxygen in the electrolyte solution in contact with the nickel anode in the anode chamber (as explained above). Therefore, removing oxygen in the anode loop is usually more important than removing oxygen in the cathode loop. Therefore, it may be more effective to install the oxygen scavenger 480 in the anode loop 425 but not in the cathode loop 435, thereby concentrating the oxygen scavenging force on the electrolyte solution flowing into the anode chamber 420. be able to. For example, in some embodiments, smaller and more cost effective oxygen scavengers can be used if only the treatment of the solution flowing through the anode chamber is required. Further, in some embodiments, low oxygen concentration can be achieved by concentrating the oxygen scavenging force on a small amount of electrolyte solution flowing through the anode chamber. For example, in some embodiments, as shown in FIG. 4B, by installing the oxygen scavenger 480 in the anode loop upstream of the anode chamber but not upstream of the cathode chamber, oxygen in the anode fluid flowing into the anode chamber The concentration can be reduced to less than about 0.5 PPM, or less than about 0.4 PPM, or less than about 0.3 PPM, or less than about 0.2 PPM, or less than about 0.1 PPM.

The fluid flowing through the flow loops of electroplating systems, such as the anode chamber recirculation loop and the cathode chamber recirculation loop, can be controlled by a system consisting of pumps, valves, or other types of fluid flow control devices, with varying fluid flows. It can be sensed or measured by various types of fluid meters. In addition, the oxygen concentration and / or pH level of the electrolyte solution flowing through the various flow loops and conduits, as well as the electrolyte solution in the anode and / or cathode chamber, is installed within the electroplating system and the oxygen concentration and / in the electrolyte solution. Alternatively, it may be sensed, measured and / or determined by one or more oxygen sensors and / or pH sensors configured to measure the pH level of the electrolyte solution. Also, the electroplating system may be equipped with logic circuits for operating the oxygen scavenger in response to the value output by the pH sensor (or pH meter), and similarly, the electroplating system is an oxygen sensor. It may be provided with a logic circuit for operating the oxygen scavenging device in response to the value output by.

In addition, for the system controller of the electroplating system to remove and / or control various sensors (eg, fluid flow, oxygen, pH), various devices for fluid flow control (eg, pumps, valves), oxygen. Devices, or other devices and components that may be in the electroplating system, may be monitored, operated, and / or controlled. Although the system controller is not explicitly shown in FIG. 4A or 4B-although it may be present in embodiments of electroplating systems configured according to these figures-as described above, electroplating system 307. See the electronic unit 339 in Figure 3D, which can act as a system controller for. The system controller will be described in more detail below.

For oxygen sensors, in some embodiments, the oxygen concentration in the electrolyte solution may be monitored at one, two, or three or more locations within the electroplating system, especially the flow loops, anodes of the system. It may be monitored in the chamber and / or in the cathode chamber. With reference to FIGS. 4A and 4B again, the electroplating system 400 has one or more in the bath tank 450, the anode chamber 420, the cathode chamber 430, the anode loop 425, the cathode loop 435, and elsewhere in the electroplating system. It may be equipped with an oxygen sensor. The oxygen sensor may be a commercially available oxygen probe, such as that manufactured by In-Situ (Fort Collins, Colorado, USA). In other embodiments, a handheld oxygen meter, such as a commercially available meter manufactured by YSI (Yellow Springs, Ohio, USA), may be used.

With respect to pH sensors, in some implementations, the pH level of the electrolyte solution may be monitored at one, two, or three or more locations within the electroplating system, especially the flow loop, anode chamber of the system. , And / or may be monitored in the cathode chamber. With reference to FIGS. 4A and 4B again, the electroplating system 400 has one or more in the bath tank 450, the anode chamber 420, the cathode chamber 430, the anode loop 425, the cathode loop 435, and elsewhere in the electroplating system. May be equipped with a pH sensor. The pH level may be measured directly with a built-in pH meter or may be measured or estimated using offline bath measurement data. One suitable example of a commercially available offline pH meter is the Symphony SP70P.

With respect to the system controller, the appropriate system controller (generally) controls the oxygen concentration and / or pH level of the electroplating solution circulating in the electroplating system, as well as the task of electroplating one or more semiconductor substrates. It may have hardware and / or software to accomplish and / or related steps as a whole. The controller can act on a variety of inputs, including user inputs, but can also act on inputs sensed from, for example, oxygen or pH sensors installed in one or more locations within the electroplating system. In response to various inputs, the system controller can execute control instructions to operate the electroplating system in a particular way. For example, the controller may adjust the suction level, the position of one or more valves and the flow rate of fluid through one or more flow loops, and the level of oxygen removal performed by one or more oxygen scavengers. , Other controllable features of the electroplating system may be adjusted. For example, a system controller operates one or more oxygen scavengers to reach an oxygen concentration below or near a certain value, eg, about 1 ppm or less, or more specifically, about 0.5 ppm or less. It may be configured as follows. A system controller typically comprises one or more storage devices and one or more processors configured to execute instructions stored on a machine-readable medium, according to an embodiment disclosed by an electroplating system. It has become like. A machine-readable medium containing instructions for controlling processing operations according to the disclosed implementation may be connected to a system controller.

[Electroplating system with device for adjusting pH after pH fluctuation]

Precautionary measures-such as lowering the concentration of oxygen in the electrolyte solution in the anode chamber-are measures to reduce pH fluctuations, but another method is when a certain amount of pH fluctuations is detected or predicted to occur. Therefore, the electroplating system is equipped with a device for adjusting the pH level of the electrolyte solution. Also, the combination of the two techniques may still work even better.

Therefore, what is disclosed herein is a pH adjusting device that can be incorporated into an electroplating system and used with an oxygen scavenger to prevent, reduce or correct pH fluctuations, thereby electroplating. Improves the quality of the metal layer. Such pH adjusting devices (and related methods) are already in US Patent Application No. 13 / 706,296, filed December 5, 2012, under the title of the invention "APPARATUSES AND METHODS FOR CONTROLLING PH IN ELECTROPLATING BATHS". Please note that it is described in great detail. Therefore, by referring to this earlier patent specification, the whole picture is actually incorporated herein by reference, but in particular the embodiment is described and the above-mentioned pH adjustment device is used in an electroplating system having an oxygen scavenging device. Incorporate to explain. The terms or phrases "bath," "electroplating bath," "electroplating bath solution," "electroplating solution," "plating solution," "electrolytic plating solution," and "electrolytic solution" are interchanged herein. Please note that we are using it as much as possible.

As described in detail in the patent specification described above, the particular pH adjusting device disclosed therein electrolyzes one or more components of an electroplating bath to generate free hydrogen ions in solution. By letting it function, it can function to lower the pH of the electrolyte solution. For example, water is usually used as the solvent in the nickel plating electrolyte solution, and when water is electrolyzed with an anode that absorbs electrons immersed in the bath, four hydrogen ions are generated for each electrolysis of two water molecules. And one oxygen molecule is generated.

<maths num="11"><img file="JP6502628B2_D0011.tif" /></maths>

In nickel electroplating, the cathode reaction corresponding to the anodic reaction (11) is generally the reduction of nickel (occurs on the wafer itself, or more generally on the auxiliary cathode).

The anode used to absorb the electrons generated in the reaction of formula (11) above may be an Inactive Anode and may be embodied in a variety of shapes, sizes and configurations. It may be made of and / or coated with a variety of materials and may be exposed to the bath at various locations in the electroplating tank. The term auxiliary anode is used herein because the electroplating tank usually already has another anode electrode-usually the main anode, electroplating on some target cathode surface, usually the wafer substrate. An active (non-inactive) metal anode that serves as a source of metal to be produced. The major (s) active nickel anodes may be, for example, the nickel anode round 422 shown in FIGS. 4A and 4B. In addition, since the generation of free hydrogen ions in the bath is caused by reactions that occur on or near the surface of the auxiliary anode (eg, electrolysis of Equation 11), the auxiliary anode is referred to herein as an overall acid-generating surface or. Called "AGS".

As mentioned above, the plating rate of the cathode in nickel electroplating is usually about 97 to 99%, which is generally lower than the half-reaction of the main anode metal (mostly nearly 100% efficiency), and the overall efficiency is low. It leads to ineffectiveness, increased metal content, and increased pH in the bath. When the reaction 11 is carried out using an inert anode instead of the metal anode, the anodic efficiency at which metal is generated at the main anode is zero (0%) and the metal content in the bath decreases over time. And the pH will drop. Therefore, the two major anode approaches (active and inactive) result in contrasting pH and metal content in the bath over time. The net overall efficiency of the latter case (active metal anode) is much closer to equilibrium, but not perfect. The use of the Inactive Anode reaction with a small amount of AGS during plating can restore the metal and acid / pH balance fairly quickly. The charge required to pass through the AGS, as the ineffectiveness of cathode plating is not always constant with time or treatment conditions and is not absolutely reliable and easily predictable over a very long period of time (months or years). Not only do we need a means of predicting quantity and time, but some measurement of the metal and the pH of the bath may also be needed on a regular basis to control the composition of the bath. Therefore, according to some embodiments disclosed herein, a relatively small amount of charge (compared to one plated on a workpiece) using the AGS configuration (oxygen electrode of an inert anode connected to a metal precipitation cathode). Allows the technique to pass through) to restore equilibrium from usually 97-99% efficiency and associated pH rises and metal depletions, which use AGS cyclically. In addition, predict ineffectiveness and / or measure the pH and / or metal content in the bath and turn on the AGS system periodically until the pH and / or metal content in the bath returns to the target value. including.

In order to perform the acid generation function with the technology, the AGS is usually sufficiently positively biased against some AGS counter electrode (AGS cathode) during acid generation, and the AGS transfers electrons from the appropriate components of the electrolyte solution. Absorbs (after releasing electrons from the component) to generate free hydrogen ions on the surface of the AGS. The absorbed / released electrons may then be transferred across the external circuit to the surface of the AGS cathode, where the electrons may be absorbed (and thereby reduced) by another component of the electrolyte solution. .. The (AGS) counter electrode (or AGS cathode) may be the same as the counter electrode used in the electroplating operation or may be different from the counter electrode used in the electroplating operation. However, in electroplating, the substrate is usually negatively biased against the major (usually active metal) anode, so metal ions from the electrolyte solution are reduced and plated on the substrate surface, during acid generation. Since some electrical reconstruction (perhaps by switching various electrorelays) may be required, the AGS can generate the acid with a sufficiently positive bias against this counter electrode. In any case, AGS functions to lower the pH of the electrolyte solution. Therefore, the method of electroplating a metal to adjust the pH of the electrolyte solution is to expose the substrate surface and the counter electrode to the electrolyte solution and to apply a sufficiently negative bias to the counter electrode to reduce the metal ions on the substrate surface. It may include plating the substrate surface and applying a sufficiently positive bias to the counter electrode to AGS to generate free hydrogen ions. In some embodiments, pH adjustment can be achieved by electrolyzing water molecules with AGS to release hydrogen ions, as described above for Reaction 11.

The electrons absorbed by the AGS of the anode are guided through the conductive path to the cathode surface in contact with the electrolyte solution and may be used to reduce the solvated metal cations in the electrolyte solution. By reducing the solvated metal ions in this way, uncharged elemental metals are deposited on the above-mentioned cathode surface, thereby reducing the metal ion concentration in the bath. Reaction equation (12) is Ni²⁺This is shown in the case of.

<maths num="12"><img file="JP6502628B2_D0012.tif" /></maths>

Thus, in some embodiments, the concentration of metal ions in the electrolyte solution is effectively reduced by electrochemically reducing some of the metal ions to a nonionic metal species that deposits on the opposite electrode. Can be done. Moreover, in some embodiments, the amount of charge used to deposit the metal from the electrolyte solution may be largely related to the total charge of the electrons liberated on the AGS. Moreover, in some embodiments, the electrochemical reduction of some of the solvated metal ions occurs roughly or substantially proportional to the charge transferred by generating free hydrogen ions in the AGS. Good. Therefore, in some embodiments, the electrolysis and metal plating on the cathode surface that occurs in the AGS is substantially balanced. Due to this potential balance, at least in principle, the process of generating hydrogen ions, using some or all of the free electrons to reduce the metal ions, and plating the plate element metal. Is referred to herein as a metal-to-acid (MTA) process as a whole. This phrase is used because the exchange of metal ions with respect to hydrogen ions in the bath is performed effectively to some extent in the above-mentioned step, as shown in the reaction formula (13).

<maths num="13"><img file="JP6502628B2_D0013.tif" /></maths>

Of course, the exchange of metal to acid does not have to be perfect or complete, nor does it need to specify a ratio to one process and configure the MTA process as the term is used herein. Should be understood. In other words, as long as the majority of the electrons liberated in AGS are used to reduce metal ions to solid form, which reduces the concentration of metal ions in the electrolyte solution, this step is described herein. In the book, it is called the MTA process as a whole. In any case, the MTA process for adjusting pH fluctuations is advantageous. Because the above variation problem is most typically over-solvated metal ions-eg Ni²⁺-Proposed by the occurrence, the MTA process has the potential to ideally exchange metal ions for hydrogen ions at the correct rate to eliminate the imbalances that occur in reactions 1-7 above. Another possible advantage is that the electroplating bath somehow outperforms the electroplated metal to external metal ions (eg Ni).²⁺Cu in a sulfamic acid electroplating bath²⁺If you have ions, these external better metal ions (Cu)²⁺) Is deposited, resulting in excess important metal ions (eg Ni)²⁺) Deposition occurs. Therefore, in the embodiment in which this occurs, the composition of the electroplating bath can be further improved in the MTA process. As a result, the MTA process can extend the life of the bath, reduce injection requirements, and eliminate the need for planning to add sulfamic acid.

In some embodiments, the usual MTA process is constant current, from about 0.01 to about 10 amperes (A / L) per liter of electroplating bath fluid, or from about 0.05 A / L to about 5 A / L, or about. It can be operated and executed with a current of 1 A / L to about 4 A / L. Depending on the embodiment, an appropriate amount or time of MTA process can be described in terms of the total amount of charge (eg, unit Coulomb) transferred, preferably through the MTA process. In some embodiments, pH measurements can be used to estimate the appropriate target charge transfer in the MTA process for a given electroplating bath capacity to restore the target pH value. it can. In some embodiments, metal content measurements are used to estimate the appropriate target charge amount transferred in the MTA process for a given electroplating bath capacity to determine the target pH value or target. The metal content can be restored. The relationship between the target charge amount and the current pH level may be calculated from experimental or literature data and calculations. The current pH level may be measured directly with a built-in pH meter or measured or estimated using offline bath measurement data. In any case, the current pH level or metal content provides a mechanism for estimating the appropriate amount or time of MTA steps for a given electroplating bath.

However, pH levels or metal content are not the only way to estimate the appropriate amount or time of MTA. In some embodiments, the amount of charge transferred in the next MTA operation is preferably estimated from the system downtime since the last MTA operation and / or the charge passed in the electroplating process since the last MTA operation. You get a good foundation to do. The target amount of charge to be transferred in the next MTA operation is referred to herein as "MTA undercharge" and the relationship between "MTA undercharge" and system downtime and / or plating charge passed is usually specified. It depends not only on the chemicals of the electroplating bath, but also on the design of the electroplating equipment. In some embodiments, the target "MTA deficiency charge" that is transferred according to the passing plating charge or the downtime of the system is already characteristic of the particular system, so by tracking these amounts, " "MTA deficiency charge" can be accumulated during electroplating work, and as a result, can be performed when it is time to carry out the MTA process (for example, due to the inclusion of blank time during electroplating). The MTA process of the preferred appropriate amount or time is known. In certain such embodiments, the MTA process can be incorporated into the planned control mechanism (eg, operating software) of the electroplating apparatus, when the minimum MTA undercharge specified in advance is met, and the electroplating operation. At the time when the appropriate blank time occurs, an appropriate amount or amount of MTA steps can be performed to match the known MTA undercharge (or at least some tolerance, whichever happens first). Can be carried out for the maximum time).

The pH adjustment and / or MTA processes and equipment disclosed herein, as a whole, are combined with any metal electroplating system that uses an active anode whose cathode plating efficiency is lower than the dissolution efficiency of the anode, depending on the embodiment. Or may be used with any electroplating system that uses chemicals in the electrolyte solution that show an increase in pH during electroplating or during rest periods. Therefore, the devices and methods disclosed herein are generally for electroplating of metals plated at a potential lower (or negative) below the hydrogen generation potential at pH 0 (0 V vs. NHE). It may be applicable, and moreover, it may be applicable if the metal reduction potential is below the stability of the water to form hydrogen at the pH of the bath used. Some examples of metals in this class of materials include nickel, cobalt, indium, zinc, cadmium, chromium, antimony, tin and lead, and alloys of these materials. Examples of plating chemicals that can benefit from the pH adjustment and / or MTA processes and equipment disclosed herein by use include the following: plating sulfuric acid, sulfamic acid, chloride of iron and iron alloys: , And / or fluoroborate-based baths, indium-plated sulfamic acid-based baths, acid bromide-based cadmium-plated baths, and acidified zinc-plated baths, but not limited to.

When metal ions form a complex in the bath, the potential for reduction becomes more negative than in the non-complexed state, which is purely ineffective at the cathode of the workpiece and also carbon monoxide (CO) -hydrogen generation reaction. It can happen, and other relatively noble metal platings can. So, for example, when a strongly complexed copper solution is used (normal reduction potential is about 0.34 V vs. NHE), NHE can be negative in a sufficiently strongly complexed environment.

As pointed out, a variety of materials can be used to form AGS. In some embodiments, these materials may be similar to those known in the prior art for dimensionally stable inert electrodes (of DSA). In some embodiments, suitable materials include conductive materials, non-corrosive or corrosion resistant materials that do not substantially corrode in the subject electroplating bath. In certain such embodiments, the corrosion-resistant material may be coated with an oxygen-generating inert catalyst. In some embodiments, the corrosion resistant material of the underlying substrate may include one or more metals, such as titanium, tantalum, niobium, and zirconium. In some embodiments, the body is formed from one or more of these corrosion resistant materials, and the body is (H).₂O Covered (or partially covered) with a catalytic coating that can accelerate the hydrogen ion generation reaction in the AGS (for example, by improving the motility of electrolysis). Of course, it is important that the corrosion-resistant material that makes up the body of the AGS, whether metal or some other type of material, has an affinity for the catalytic coating. The metals listed above have the appropriate affinity. Suitable catalytic coatings for promoting water hydrolysis include platinum, or one or more metal oxides selected from oxides of platinum, niobium, ruthenium, iridium and tantalum. Suitable catalytic coatings on the market include, but are not limited to, Siemens Optima® anode coatings, this product is a mixed metal oxide (Optima IOA-) such as iridium oxide and tantalum oxide. It consists of HF) or platinum (Optima IOA-PTA).

Also, as mentioned above, the AGS can be configured in many ways in terms of size, shape, location, orientation, etc., and various specific AGS embodiments are presented in the background of FIGS. 5A, 5B, and 5C. Will be disclosed in detail below. Of course, these embodiments incorporate the concepts of the invention disclosed herein, with the understanding that the concepts of these inventions are not limited to the scope of the specifically described AGS configuration. It is described in detail for explanation. (For example, H₂Since it is the surface of the AGS that promotes the hydrogen ion generation reaction (to improve the motility of O electrolysis), a structure with a large surface area per unit volume may be preferable in some cases. In some embodiments, the mesh-like structure has such a large surface area per unit volume. AGS is an anode surface that functions separately from the normal anode and cathode surfaces present in electroplating tanksthat is, the wafer substrate of the cathode and the metal ion source of the anodebut in AGS it is normally present in electroplating tanks. It should also be noted that the common power supply can be biased by the potential of the anode-although it may be modified in some cases. For example, as described in more detail below, in some embodiments, the AGS can be biased with a positive anodic potential through the same leads and power sources that normally bias the substrate with a negative cathode. This can sometimes be achieved by switching or reversing the polarity of the power supply, or by using relays to change the connection from the power supply to the leads of the board.

Depending on the embodiment, the AGS can provide an overall overview in association with pH adjustment and / or pH control procedures that form subparts of the method of electroplating a series of substrates, or pH adjustment and / or pH. An overall overview can be seen as a component of the device or system that electroplats the substrate related to control. Therefore, it is useful to provide a description and description of some AGS implementations that may be used within an electroplating system. However, again, it is understood that the electroplating systems disclosed below are described to describe various possible AGS-related configurations and pH control applications in general but specific terms. Should be. The specific hardware disclosed is not intended to limit the scope of the invention concept associated with the disclosed AGS. In addition, any AGS configurations and implementations described below in the context of FIGS. 5A, 5B, and 5C may be used in combination with the oxygen scavengers previously shown in FIGS. 4A and 4B. Should be understood.

AGS is typically used with an electroplating tank that houses the anode, which serves as a counter electrode to the substrate during electroplating and also as a metal source for electroplating the substrate. In some embodiments, this anode may also serve as a counter electrode to the AGS. In other embodiments, the AGS can be biased against different opposite poles. The AGS itself may or may not be integrally formed with the electroplating tank, which will be described in more detail below. In some embodiments, it is a self-contained AGS system that has its own electrodes, pH meter, power supply and controller, which can communicate with the main plating tool equipment controller (eg wafer or if necessary). There is a system (which tracks the charge that has passed through the bath). Some of the elements of the system (ie, a selection list from the elements of the system) may be placed in the bath, mounted in the bath, hung on the wall of the bath, and placed in the liquid of the bath (eg electrodes). And / or immerse the pH meter in the electrolyte of the bath). Sublists selected from the elements of the system include 1) an AGS inert and dimensionally stable electrode, 2) a cathode suitable for plating the metal contained in the bath (eg made from bath metal). A cathode or platinum-coated substrate that can be subsequently plated with bath metal, and later with bath-plated metal to occasionally regenerate the exposed Pt surface), 3) to electrodes. There may be electrical connections, and 4) pH probes, etc. The components of the system that are not immersed in the bath include a power source for passing current between the electrodes and a controller that communicates with the pH probe, which converts the pH probe signal into a pH reading for the bath. There may be a controller that monitors the pH and obtains a signal from the probe to determine when and how to control / start the power / current to the power supply, the current and the charge to the time. The electroplating tank is an electroplating tank and an electroplating bath. It may include one or more fluid connectors configured to establish a fluid connection with an external container that acts as a fluid tank. In some embodiments, the AGS and possibly its counter electrode may be placed within this outer container. The fluid connector may be configured so that the electroplating bath fluid can be circulated in the plating tank and guided toward the surface of the electroplated substrate. Further, in some embodiments, the electroplating tank may include a membrane or other separator designed to provide some fluid separation between the anode and cathode compartments, and the chemicals in different electroplating bath fluids. Can be maintained in two compartments.

In an electroplating system with multiple electroplating tanks, the electroplating of the substrate performed in each of these tanks' electroplating baths maintains the bath pH using the acid generating surface (AGS) described above and / Or it can be achieved by adjusting procedures. In some embodiments, a data processing system in or connected to an automatic electroplating device tracks the ongoing electroplating in individual tanks and enters each tank. Also track the composition of the bath and / or the pH of the bath. When the data processing system determines that the pH level of the electroplating bath fluid contained in a particular electroplating tank is (or is likely to be) above the required and / or desired pH range, the data processing system is located. An AGS-based pH adjustment procedure may be initiated for a given electroplating bath. Some of the key points a data processing system can rely on in determining whether a given tank is out of range or likely to be are: but not limited to: pH levels in a particular tank. One or more directly measured values, counts or estimates of the number of substrates plated in a particular tank after the last pH correction procedure, electroplating steps performed in a particular tank since the last pH correction operation The count or estimate of the total charge transferred by, the total time that a particular electroplating tank has been dormant since the last pH correction operation, and / or the accumulation corresponding to a particular electroplating tank (discussed above). ) MTA undercharge. If the data processing system reliably determines that the bath pH level in the tank is or is likely to be outside the desired pH range, the data processing system may initiate an AGS-based pH correction procedure. You don't have to. This procedure is based on yet other points, including, but not limited to: How far the bath pH level of a particular tank is from the desired range, and whether the tanks outside that particular range are currently electroplating the substrate-at least if electroplated, this substrate is complete. It seems justified to postpone the pH correction until. In some embodiments, the MTA process is parallel to the post-electroplating of the substrate step, such as the process of rinsing and reusing the substrate, and the substrate removal step, which is performed for very little time.

Another set of points that the data processing system may consider in deciding whether to initiate pH correction based on AGS is with respect to the condition of the other tanks in the electroplating system. In some embodiments, the timing of initiating AGS-based pH correction for individual electroplating baths was accumulated in bath pH levels measured in other electroplating tanks, in other electroplating tanks (as described above). ) Identification of tanks with electroplating baths with the highest MTA undercharge, highest pH or highest MTA undercharge, whether to maintain or achieve acceptable substrate processing throughput that requires immediate electroplating of the substrate, Also related to this may be whether there is another tank ready to use to receive the electroplating substrate, and so on.

If it is decided to initiate an AGS-based pH adjustment procedure within the data processing system, in some embodiments the system will temporarily unavailable (s) tanks to correct the pH. Start by specifying. After this designation, the AGS-based pH adjustment procedure is initiated for the designated tank and the postponed electroplating. After the pH adjustment is complete, with the current pH level within acceptable limits, the data processing system redesignates these tanks available for plating, which tanks re-pH these specific tanks. It remains so specified until the adjustment criteria are met.

The data processing system has described making such a decision regarding the start of pH correction based on AGS, but of course, there is one act of making the above points and judgment regarding the start of pH correction based on AGS. It is easily understood by those skilled in the art that the operator of any electroplating apparatus having the above series of electroplating tanks may perform the operation manually. In some embodiments, it is preferred to automate the decision-making process and the analysis of the above points using the data processing system described above, whereas in other embodiments manual analysis and control are advantageous and preferred. There is.

The configuration of another multi-tank electroplating system that may use AGS requires an electroplating bath tank that shares two or more or all of the system's electroplating tanks in a fluid connection. Each tank usually has its own electroplating bath, in which electroplating is performed, but in some embodiments, a common shared tank is fluidly connected to each bath. A spare electroplating bath fluid can be provided. In some embodiments using shared tanks, the AGS-based pH adjustment procedure may actually be performed within the shared tank itself rather than within the individual plating tanks. In certain such embodiments, this eliminates the need for individual electroplating tanks to have their own AGS, but more importantly, taking the individual electroplating tanks offline (ie,). The need to bring the pH level of the tank within the desired range (designated not to be used for electroplating) can be eliminated. Therefore, in this type of configuration, instead of monitoring and adjusting the pH level within the individual electroplating tanks, the pH level of the shared bath tank is monitored without the need to delay the electroplating operation within the individual tanks. It can be adjusted continuously, and at the same time, the pH level in each tank is maintained within the specifications by fluid connection to the shared tank. However, it should also be noted that the incorporation and use of electrolyte solution bath tanks is not limited to multi-tank electroplating system configurations-shown in bath tank 450 shown in FIGS. 4A and 4B. As described above, the bath tank can be used even in the configuration of a single tank. In addition, depending on the embodiment, for many of the same reasons just mentioned-for example, an electroplating tank without specifying a tank 410 so that it cannot be used for electroplating (as described above) when installed in this way. It may be appropriate to install the AGS inside the bath tank 450, for example, it may be possible to adjust the pH of the electrolyte solution in the 410.

As mentioned above, the AGS itself can be configured in many ways in terms of size, shape, location, orientation, and so on. Of course, it is not possible to provide a detailed description of all possible configurations that are feasible and consistent with the concepts of the invention disclosed herein. Therefore, as also described above, the embodiments described below with respect to FIGS. 3A, 3B, and 3C should be viewed as illustrating, but not limited to, the concepts of the invention within the scope of the present disclosure. Is. Furthermore, it should be noted that the AGS configurations described with respect to FIGS. 3A, 3B, and 3C may optionally be implemented within an electroplating system having an oxygen scavenger, as shown in FIGS. 4A and 4B. I want to be.

FIG. 5A schematically illustrates one embodiment of an acid generating surface (AGS) that is designed in a disk-like configuration so that it can be inserted into the displayed electroplating tank 510 instead of the semiconductor substrate. In some embodiments, the disc comprises a catalytically coated body, which releases hydrogen ions from one or more components of the electroplating bath when a sufficient positive voltage is applied to the disc. In certain such embodiments, hydrogen ions are released from water molecules by electrolysis on the surface of the catalytic coating. In some embodiments, the body of the disc can include a conductive and corrosion resistant material that does not substantially corrode in the electroplating bath, such as titanium, tantalum, niobium, or zirconium. In some embodiments, the coating may contain either platinum or one or more metal oxides selected from oxides of iridium and tantalum. In some embodiments, the diameter of the disc may be selected from about 100 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, and about 450 mm. In some embodiments, the diameter range may be suitable for discs where the upper and lower limits of the possible range are selected from any combination of diameters listed above. In some embodiments, the thickness of the disc may be selected from about 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm. In some embodiments, the thickness range may be suitable for discs where the upper and lower limits of the possible range are selected from any combination of the diameters listed above.

Also shown in FIG. 5A is a clamshell assembly 520 consisting of a cup / cone into which the AGS disk 500 is inserted. In configuration 522 with the assembly open, the clamshell assembly is ready to receive the AGS disk 500, as indicated by arrow 502 in the figure. After the AGS disk 500 is inserted, the clamshell is manipulated to a closed configuration 524 as indicated by the dashed double-headed arrow 504. After closure, with the AGS disk 500 in place, the clamshell assembly 520 is lowered into the plating tank 510, specifically into the electroplating bath 512 as indicated by arrow 506. Be taken down. At this point, the AGS is in a position to perform the metal-to-acid (MTA) process as described above.

In this embodiment, nickel is the electroplated metal-hence the nickel anode 514 in the figure-so the overall action of the MTA process is as described in detail above, Ni²⁺Cation H⁺It is to exchange for ions. Further, in this embodiment, the nickel anode 514 acts as a counter electrode to the AGS disk 500, so that the MTA process plating the solid Ni back into the nickel anode 514, which actually functions as the cathode. .. Therefore, in the MTA process, the AGS disk 500 is positively biased against the nickel anode 514, which again serves as the counter electrode of the cathode to AGS during MTA, which is the clamshell during electroplating. It is the opposite of the bias applied to the substrate held inside. Therefore, the power supply 530 shown in FIG. 5A is capable of reversing the polarity of the voltage difference, which is applied to the AGS disk and nickel anode. Although FIG. 5A schematically shows the polarity reversal that occurs in the power supply 530, it should be understood that this polarity reversal may be performed using an external electrical switching mechanism.

Also shown in FIG. 5A are a bath tank 540 and a recirculation pump 542, both of which together increase the capacity of the electroplating bath fluid that can be used in the electroplating tank 510. Again, note that a single bath tank can supply reserve capacity electroplating bath fluid to multiple electroplating tanks 510, as described above with respect to FIG. In the embodiment shown in FIG. 5A, the pH adjustment based on AGS is carried out in the plating tank 510 itself, despite the presence of the bath tank.

In some embodiments, the AGS disc 500 shown in FIG. 5A may be used in an automated tooling manner. For example, the AGS disk 500 may be used in the MTA process to adjust the pH levels of the individual tanks 309, 311 and 313 of the electroplating system 307 in Figure 3D. With reference to FIG. 3D, in certain such embodiments, the AGS disk 500 may be treated and stored like a dummy substrate, with specific tanks 309, 311 and 313 designated for pH correction. -Based on the above points-The AGS disk can be moved to a specific tank designated for pH correction by the back-end robot 325 and used in the MTA process to adjust the bath pH level in the designated tank.

The acid generating surface (AGS) may be used as a substantially integral part of the electroplating apparatus, or more specifically, as a substantially integral portion fixed to some internal part of the electroplating tank. Good. For example, the AGS may be in each of the electroplating tanks 309, 311 and 313 of the electroplating equipment shown in Figure 3D, so that the pH can be adjusted by contacting the electroplating bath in each tank. May be. Therefore, as a whole, an electroplating tank configured to contain an electroplating bath, a table for holding the substrate in the electroplating bath, and a voltage bias on the substrate while the substrate is held on the table. Sufficient for the electrical contact of the substrate configured to supply, the electrical contact of the counter electrode configured to supply the voltage bias to the counter electrode while in contact with the counter electrode, and the electrical contact of the counter electrode. AGS configured to generate free hydrogen ions in the bath when a positive positive voltage bias is applied, and a negative voltage bias on the electrical contacts of the substrate with respect to the electrical contacts of the opposite poles-metal ions from the bath To supply a positive voltage bias to the AGS for the electrical contacts of the counter electrode-sufficient to generate free hydrogen ions in the AGS. The electroplating apparatus can be configured to include one or more configured power units.

FIG. 5B is a schematic representation of an electroplating apparatus 550 with an integrated AGS component 560 to perform a pH adjustment procedure. In this figure, the integrated AGS component is in the form of an AGS ring 560 mounted on the inner wall of the electroplating tank 510. One possible benefit of the ring-shaped AGS560 shown in Figure 5B is that by installing the AGS radially outward in the electroplating tank 510, the oxygen gas bubbles generated by this AGS are the location of the substrate. It tends to dissipate radially away from the substrate, which reduces the possibility of interfering with the substrate and forming foreign matter on the substrate surface. Thus, in some embodiments, the substrate may remain in the bath and away from the bath during the MTA operation if the oxygen bubbles are sufficiently dissipated. In some embodiments having a ring-shaped AGS as shown in FIG. 5B, an additional membrane may be provided on top of the ring-shaped AGS 560. This membrane can function to further protect the substrate from oxygen bubbles generated in the AGS ring during the MTA process. Other components of the electroplating apparatus 550 shown in FIG. 5B include an electroplating tank 510, a clamshell assembly 520, a power supply 530, a bath tank 540, and a pump 542. The bath tank 540 and the recirculation pump 542 provide the same functionality as described above with respect to FIG. 5A.

For electroplating the substrate, the clamshell assembly 520 holding the substrate (which is not visible) was lowered into the electroplating bath 512 (as indicated by arrow 506) and used with power supply 530. A negative voltage bias is applied to the substrate (via the electrical contacts of the substrate (not shown)) against the nickel anode 514 which acts as the counter electrode (via the electrical contacts of the counter electrode (not shown). To carry out the MTA pH adjustment procedure described above, electroplating is completed and the substrate is pulled out of the bath and nickeled with a positive voltage bias-that is, having a polarity opposite to the polarity used for electroplating. It is applied to the AGS (ring) 560 with respect to the anode 514 to generate an acid at the AGS (ring) 560. In the AGS ring configuration shown in Figure 5B, the bath H⁺In addition to increasing the concentration, extra Ni is added by performing the MTA process.²⁺Is deposited again and returns to the nickel anode 514, similar to what happened with the AGS disk configuration shown in Figure 5A.

In the embodiment shown in FIG. 5B, the positive (ie reverse) voltage bias is applied by the same power unit / power source 530 that applies a negative voltage bias to the substrate during electroplating. Therefore, the power unit / power supply 530 shown in FIG. 5B supplies a negative voltage bias to the electrical contact of the substrate-in this case the nickel anode 514-to the electrical contact of the counter electrode and positive to the nickel anode 514. The voltage bias also acts as a dual purpose power unit configured to supply the AGS ring. Further, in some embodiments using a power unit having two purposes, the electroplating apparatus is one or more that controls various electrical connections in order to perform voltage bias applications of different polarities between the AGS and the substrate. It may be equipped with an electric relay. Therefore, in some embodiments, a first relay that controls the electrical connection between the dual purpose power supply / power unit and the electrical contacts of the board, and the dual purpose power unit and the AGS. There may be a second relay that controls the electrical connection between them. In certain such embodiments, during electroplating, the first relay is closed, the second relay is open, and a negative voltage bias to the electrical contacts of the counter electrode is supplied to the electrical contacts of the substrate. In the MTA process, the first relay is open and the second relay is closed to provide a positive voltage bias to the counter electrode electrical contacts to the acid generating surface. This type of configuration is schematically shown in FIG. 5B, in which the plating relay 532 acts as the first relay described above and the MTA relay 534 acts as the second relay described above. While using one power unit with two purposes has some advantages (possibly low cost, small size, etc.), it is possible to configure with more than one power supply / power unit. Please note. For example, the electroplating apparatus 550 provides a first power unit configured to supply a negative voltage bias to the electrical contact of the counter electrode to the electrical contact of the substrate and a positive voltage bias to the electrical contact of the counter electrode. To supply to the acid generation surface It may include a configured second power unit. A series of electrical relays may be used to control electrical connections and voltage bias applications in configurations with multiple power units, similar to the method using such relays in FIG. 5B.

In some embodiments, the separate AGS (Inactive Anode) and cathode (counter electrode) in the bath are by monitoring the pH of the bath to determine when to turn it on and for how long to correct the pH. , Computer controlled. The bath communicates with electrolytes in one or more tanks. Avoiding air bubbles from entering the tank by raising the air bubbles and / or deflecting the membrane (porous) around the electrodes of the AGS system to prevent the air bubbles from entering the tank flow.

Thus, in some embodiments, the device has a volume of electroplating bath fluid that is different from the volume of fluid contained in one or more electroplating tanks in which the device performs pH maintenance and / or adjustment. AGS may be used. With such an AGS, including a pH adjusting device, one or more fluid connections between the device and one or more electroplating tanks allow the bath fluid to be exchanged and the hydrogen ions generated by the device You will be able to transfer to one or more tanks. So, for example, in some embodiments, such a device may be an acid generating bath tank (AGBR), which tank is with a container configured to hold a volume of electroplating bath fluid. A fluid connector configured to establish a fluid connection between this vessel and the electroplating tank, an AGS and counter electrode electrical contacts located with the vessel, and a positive voltage bias to the counter electrode electrical contacts. It comprises one or more power units configured to supply the AGS sufficient to generate free hydrogen ions. According to other embodiments of AGS disclosed herein, free hydrogen ions can be generated in AGS by electrolysis of water molecules, in this case within the volume of electroplating bath fluid in the AGBR. In some embodiments, the fluid connector between the AGBR and the electroplating tank is an inlet tube configured to accept a (continuous or periodic) flow of electroplating bath fluid coming from the electroplating tank. Electroplating bath An outlet tube configured to direct the flow of fluid to an electroplating tank and a fluid connection to the inlet and / or outlet tube to provide fluid pressure into the inlet and / or outlet tube. It may be equipped with a recirculation pump. Such an AGBR is designed to increase the concentration of hydrogen ions in the (s) electroplating tank to which this tank is connected, so that the pH of the electroplating bath fluid flowing into the outlet tube is Overall lower than the pH of the electroplating bath fluid flowing into the inlet tube (if AGS was on or off). In some embodiments, AGB

Figure 5C shows the AGBR device 560, which shows a number of the features mentioned above. In this figure, the AGBR is a container 566 configured to hold a volume of electroplating bath fluid 568, and an AGS 562 and counter electrode 564, both placed in the container and in contact with the bath fluid, and a counter electrode 564. A power supply unit / power supply 570 configured to generate hydrogen ions in the bath fluid 568 by applying a positive bias voltage to the AGS562, a recirculation pump 542, and an AGBR device 560 in the electroplating tank 510. It has fluid connectors 544 and 546 to connect. In some embodiments, the counter electrode, which effectively acts as a cathode, may consist of nickel and / or titanium.

The electroplating tank 510 connected to the AGBR device 560 in FIG. 5C and its associated components is similar to that schematically shown in FIG. 5B. Included in Figure 5C is the clamshell assembly 520, the electroplated bath 512 in the tank 510, the clamshell assembly 520 ready to be unloaded into the bath 512 (as indicated by arrow 506), the bath. A power unit / power source 530 configured to supply a nickel anode 514 in 512 and a negative bias voltage to the nickel anode 514 to a substrate (not shown) in the clamshell assembly 520. However, one important difference is that the electroplating tank 510 in Figure 5C does not contain AGS inside itself. Instead, the pH level is regulated and maintained within the electroplating bath 512 via fluid connections 544 and 546 with the acid generating bath tank 560.

FIG. 5C shows an acid generation bath tank (AGBR) 560 that is physically separate from the electroplating tank 510, but in some embodiments the two are in the AGBR. As long as the volume of the bath fluid is different (even if connected) from the volume contained in the tank 510, it may be physically adjacent or attached to each other. Moreover, in some embodiments, the AGBR is actually installed in the electroplating tank 510, again as long as the volume of bath fluid contained in the AGBR is different from the volume contained in the tank 510. It's okay. In other embodiments, the AGBR may be installed in an electroplated fluid recirculation loop connected to a tank 510 similar to that shown in FIG. 5C. Thus, depending on the configuration, the AGBR can be reasonably viewed as one component of the electroplating apparatus 550 and, in other embodiments, as another device.

Further, in some embodiments, the AGBR can serve as a component within the multi-tank electroplating apparatus, such as the automatic electroplating apparatus 200 shown in FIG. As discussed above, tank 207 of device 200 may be fluid-connected to a shared electroplating bath tank (which is not shown in FIG. 2), and in some embodiments, this shared tank It may contain AGS and counter electrode as shown in Figure 5C. As described above, in certain such embodiments, the presence of AGS and counter electrode in the shared tank eliminates the need for individual electroplating tanks to have their own dedicated AGS. More importantly, it eliminates the need for individual electroplating tanks to discontinue electroplating operations while the pH level is within the desired range. Therefore, some advantages can be gained from a shared tank that functions as an AGBR in an electroplating apparatus with multiple tanks.

The AGBR560 has an AGS 562 and a counter electrode 564 in the electroplating bath fluid 568 with a different capacity than the capacity of the electroplating tank 510 to which the fluid is connected, so the AGBR560 differs from the power supply 550 used for electroplating the tank 510 It often uses its own dedicated auxiliary power supply / power unit 570. In some embodiments, a dedicated power source 570 can be used to allow the MTA process in the AGBR560 to proceed in parallel (simultaneously) with the electroplating work in progress in the electroplating tank 510. However, in some embodiments, a dedicated auxiliary power supply is not always necessary or suitable.

For example, electroplating equipment with multiple tanks (as in 307 in Figure 3D) is currently using that power source to electroplat the workpiece if the supplemental power supply for AGBR is not economically viable. Can be "rented" from no electroplating tanks 309, 311 and 313. This "borrowing" is through a system of relay switches that can connect the positive leads of the "borrowed" power supply to the AGBR's AGS and the ground or negative leads of the "borrowed" power supply to the opposite pole of the AGBR. Can be achieved. In some embodiments, the aforementioned data processing system may be used to "borrow" power and perform the necessary planning settings required to operate the appropriate electrical relays and / or switches.

Unlike the AGS implementations discussed above with respect to Figures 5A and 5B, the AGBR560's operation requires extra Ni.²⁺Note that the cations are present in the electroplating bath 512 and are removed from the bath via the MTA process, but do not reprecipitate and return to the nickel anode 514 in the electroplating tank 510. Instead, Ni removed from bath 512²⁺The cations are deposited on the counter electrode 564 in the AGBR vessel 566. However, the amount of nickel that is not collected again at the anode 514 is generally much smaller than the capacitance of a normal nickel anode.

[How to utilize the decrease in oxygen concentration]

Further, what is disclosed in the present specification is a method of electroplating a metal onto a semiconductor substrate, which is a method of reducing the oxygen concentration of at least a part of an electrolyte solution used in the electroplating operation. In some embodiments, the electroplated metal is nickel, and in some embodiments the oxygen concentration in the electrolyte solution is reduced to about 1 PPM or less. In some embodiments, the oxygen concentration in the electrolyte solution drops to about 10 PPM or less, or more specifically to about 5 PPM or less, or even more specifically to about 2 PPM or less, or even more. More specifically, it drops below about 0.5 PPM.

These methods can be carried out in the electroplating tank as described above. Therefore, in some embodiments, the electroplating tank may have an anode chamber containing a metal anode (eg, a nickel anode), a cathode chamber, and a porous separator between the anode chamber and the cathode chamber. The porous separator is as described above, and may be configured to allow an ionic current to pass during electroplating but to block the passage of the electrolyte solution at least to some extent.

Therefore, in some embodiments as shown in FIG. 6, the electroplating method 600 uses the lowering step 610 to lower the oxygen concentration in the electroplating solution and the lowering oxygen concentration in the anode chamber of the electroplating tank. Flowing step 620, contact step 630 in which the electrolyte solution having a reduced oxygen concentration is brought into contact with the nickel anode in the anode chamber, and electroplating step 640 in which the nickel from the electrolyte solution is electroplated on the substrate in the cathode chamber. May include. In some embodiments, the electrolyte solution in the cathode chamber is about pH 3.0 to 5.0, or more specifically about pH 3.5 to 4.5, or even more specifically about pH 3.8 to 4.2. , The pH may be maintained within some predetermined range. In some cases, any two or more of steps 610, 620, 630, and 640 may be performed simultaneously. In various embodiments, steps 610, 620, and 630 are performed simultaneously, during which the electroplating system is paused; that is, no electroplating is performed during that time. In some implementations, steps 610, 620, and 630 are performed continuously, during which time electroplating steps 640 are performed intermittently, whenever the board is present and the board is electroplated. To do. In this way, the oxygen concentration of the anolyte remains low and the pH of the anolyte remains stable while the system is idle during the electroplating / substrate cycle.

Further, in some embodiments, the electroplating method involves a cathode chamber in which the concentration of oxygen in the electrolyte solution flowing into the anode chamber is lower than the concentration of oxygen in the electrolyte solution flowing into the cathode chamber. It may further include running the electrolyte solution. FIG. 4B schematically illustrates the electroplating system 400, in which case the concentration of electrolyte solution flowing into each of the anode and cathode chambers 420, 430 during work may be as described above. Due to the fact that the oxygen scavenger 480 is installed in the anode chamber recirculation loop 425 but not in the cathode chamber recirculation loop 435, as described in detail above with reference to FIG. 4B.

The characteristics of the electrolyte solution used in the electroplating methods described herein may vary. For example, depending on the embodiment, the oxygen concentration of the electrolyte solution may be about 10 PPM or less, or about 5 PPM or less, or about 2 PPM or less, or about 1 PPM or less, or about 0.5 PPM or less, or about 0.2 PPM or less. The pH range was also discussed above, but as discussed, a suitable pH range may be about pH 3.5 to 4.5, or about pH 3.0 to 5.0, or about pH 3.8 to 4.2. Similarly, depending on the embodiment, the temperature of the electrolyte solution during the electroplating operation may be above about 20 degrees Celsius, above about 30 degrees Celsius, above about 35 degrees Celsius, or above about 40 degrees Celsius. It may be maintained above, above about 45 degrees Celsius, above about 50 degrees Celsius, or above about 55 degrees Celsius. In particular, in the case of nickel electroplating, the temperature of the electrolyte solution during the electroplating operation is above about 35 degrees Celsius, above about 40 degrees Celsius, above about 45 degrees Celsius, or above about 50 degrees Celsius. Alternatively, it may be maintained above about 55 degrees Celsius, above about 60 degrees Celsius, or about 30-60 degrees Celsius, or about 35-55 degrees Celsius, or about 40-50 degrees Celsius.

As far as the composition of the electrolyte solution is concerned, for nickel plating, some suitable nickel sulfamate plating bath solutions may be used, such as those sold by Enthone, DOW Nikal BP, and Shitaya. .. Details are listed in the table below.

<tables num="1"><img file="JP6502628B2_D0014.tif" /></tables>

It should be noted that most commercially available nickel plating solutions contain "anode active substances" such as nickel chloride and / or nickel bromide to promote uniform corrosion of the anode. A "brightener" may be used in the nickel electroplating solution, but in some embodiments this is neither necessary nor suitable. In some embodiments, such brighteners, nickel additives, may be added for general granulation purposes. One example is saccharin, which has traditionally been used in nickel sulfamate baths. Many organic "additives" commonly used for copper electroplating are generally not used for nickel electroplating. However, boric acid now usually acts as a cathode buffer at concentrations below about 45 g / L to avoid crystallization.

A variety of techniques and methods are available to reduce the oxygen concentration in the electrolyte solution flowing into the anode and / or cathode chambers. In some embodiments, lowering the oxygen concentration in the electrolyte solution may include degassing the electrolyte solution. In some embodiments, lowering the oxygen concentration in the electrolyte solution may include sparging the electrolyte solution with a substantially oxygen-free gas. The substantially oxygen-free gas may be, for example, an inert gas such as nitrogen and / or argon.

Some electroplating methods, if some process conditions in the electroplating tank deviate from the prescribed operating range, can be used by the electroplating system operator-even a human operator, such as by an automated system controller. Even if-may include sending messages, alerts, warnings, etc. So, for example, some electroplating methods sense the pH of the electrolyte solution in the electroplating tank and the sensed pH is above about pH 4.5, or above about 4.2 in some embodiments, or Some embodiments may include the step of sending an alert above about 5.0.

Similarly, some electroplating methods may include adjusting processing parameters, conditions, etc., when it is determined that some processing conditions in the electroplating tank are outside the predetermined operating range. So, for example, some electroplating methods sense the pH of the electrolyte solution in the electroplating tank and the sensed pH is above about 4.5, or above about 4.2 in some embodiments, or in some embodiments. If the form is above about 5.0, it may include the step of further lowering the oxygen concentration in the electrolyte solution before flowing into the anode chamber. In another embodiment, the electroplating method senses the oxygen concentration in the electrolyte solution in the anode chamber and the sensed oxygen concentration is above about 1 PPM, or above about 0.5 PPM in some embodiments. Or above about 2 PPM in some embodiments, above about 5 PPM in some embodiments, or above about 10 PPM in some embodiments, oxygen in the electrolyte solution before flowing into the anode chamber. It may include a step of further reducing the concentration.

More generally, the techniques disclosed herein are the pH of an electrolyte solution while electroplating a metal (such as nickel) from the electrolyte solution onto a semiconductor substrate in an electroplating vessel having an anode chamber and a cathode chamber. Can be seen as a way to prevent the rise above a predetermined maximum pH level. Such a method may include a step of lowering the oxygen concentration in the electrolyte solution to around or below a predetermined maximum oxygen concentration level before the electrolyte solution flows into the anode chamber of the electroplating tank. Depending on the embodiment, a suitable predetermined maximum pH level may be pH 5.0, or pH 4.5, or pH 4.2, and a suitable predetermined maximum oxygen concentration level may be 10 PPM, or 5 PPM, or. It can be 2PPM, or 1PPM, or 0.5PPM, or 0.2PPM, or 0.1PPM.

In various embodiments, a method of lowering the oxygen concentration of the anolyte is used in combination with a direct method of lowering the pH of the anolyte. Such a direct method includes a method using AGS (acid generation surface) described with respect to FIGS. 5A to 5C. As an example, the method using operations 610, 620 and 630 is carried out continuously in a normal wafer processing process. Work 640 is performed whenever the wafer is electroplated. Periodically, in this method, as described above, the method is switched to the method in which the acid is generated from the acid generation surface. When the pH returns to the specified value (or when it is determined that the acid generation process has progressed to a sufficient extent), the acid generation process may be stopped for a certain period of time.

[Experiment]

To explain the effect of oxygen scavenging on pH fluctuations in the electroplating tank, pH against a dormant electrolyte bath solution that remains in contact with the nickel anode for 10 days (ie, with no moving charge). The measurement was performed. The results are shown in Figure 6. As can be seen, without oxygen removal, the pH of the electrolyte solution rose from 3.8 to 4.5 after 7 days. The dissolved oxygen concentration of this electrolyte solution when flowing into the anode chamber was ~ 4.8 ppm.

In contrast, when oxygen removal was performed, the concentration of dissolved oxygen in the electrolyte solution flowing into the anode chamber dropped to ~ 0.7 ppm. As shown in FIG. 7, the results showed only a very gradual increase in the pH of the electrolyte solution from pH 4.1 to pH 4.4 over the same 7 days. Therefore, as shown in FIG. 7, it was shown that the pH fluctuation observed in the resting nickel electroplating bath solution was significantly reduced by oxygen removal.

Furthermore, if the dissolved oxygen concentration of the anode liquid flowing into the anode chamber is further lowered, the pH fluctuation is expected to be even lower than that shown in FIG. Among other reasons, this is supported by the fact that the nitrogen purification experiment in Figure 1C (~ 0.2PPM dissolved oxygen) did not charge the pH for 10 days.

[Other Embodiments]

Although the above processes, systems, devices, and compositions have been described in some detail for the purpose of facilitating a clear understanding, some changes and modifications may be made within the scope of the appended claims. It will be obvious to those skilled in the art. It should be noted that there are many alternative ways to implement the processes, systems, equipment, and compositions disclosed herein. Accordingly, the disclosed embodiments are considered descriptive rather than limiting, and the scope of the appended claims is not limited to the particular details of the embodiments described herein. ..<u style="single">For example, the present invention can be implemented as the following application examples.</u><u style="single">[Application Example 1] An electroplating system for electroplating nickel on a semiconductor substrate.</u><u style="single"> It is equipped with an electroplating tank configured to hold the electrolyte solution during electroplating and an oxygen scavenger.</u><u style="single"> The electroplating tank is</u><u style="single"> With the cathode chamber;</u><u style="single"> With an anode chamber configured to hold the nickel anode during electroplating;</u><u style="single"> A porous separator located between the anode chamber and the cathode chamber, which allows an ionic current to pass through during electroplating but blocks the passage of an electrolyte solution;</u><u style="single"> With a wafer holder for holding the wafer during electroplating</u><u style="single"> With</u><u style="single"> The oxygen scavenger was configured to reduce the oxygen concentration in the electrolyte solution as it flows into the anode chamber during electroplating and during pauses when the system is not electroplated.</u><u style="single"> Electroplating system.</u><u style="single">[Application Example 2] The electroplating system according to Application Example 1, wherein the porous separator can maintain a difference in oxygen concentration between the anode chamber and the cathode chamber.</u><u style="single">[Application Example 3] The electroplating system according to Application Example 1, wherein when the electroplating system is not electroplated, the electrolyte continues to flow into the anode chamber during some or all of the rest period.</u><u style="single">[Application Example 4] The electroplating system according to Application Example 3, wherein the oxygen removing device is configured to reduce the oxygen concentration in the electrolyte solution flowing into the anode chamber during a part or all of the rest period.</u><u style="single">[Application Example 5] The oxygen scavenging device measures the concentration of oxygen in the electrolyte solution flowing into the anode chamber during a part or all of the rest time, and the electrolyte solution when it is in contact with the nickel anode during the rest time. The electroplating system according to Application Example 4, which is configured to reduce the pH of the device to a level that does not increase significantly.</u><u style="single">[Application Example 6] The electroplating system according to Application Example 1, wherein the oxygen removing device is configured to reduce the oxygen concentration in the electrolyte solution to a level of about 1 ppm or less.</u><u style="single">[Application Example 7] The electroplating system according to Application Example 6, wherein the oxygen removing device is configured to reduce the oxygen concentration in the electrolyte solution to a level of about 0.5 ppm or less.</u><u style="single">[Application Example 8] The electroplating system according to Application Example 1, wherein the system is configured to expose the electrolyte solution to the atmosphere while electroplating nickel on the substrate.</u><u style="single">[Application Example 9] The electrolyte solution is connected to the fluid inlet entering the anode chamber, the fluid outlet exiting the anode chamber, the fluid inlet and the fluid outlet, and while electroplating nickel on the substrate. The electroplating system according to any one of Application Examples 1 to 8, further comprising an anode chamber recirculation loop configured to flow the water into the anode chamber.</u><u style="single">[Application Example 10] A bath tank installed outside the electroplating tank for holding an electrolyte solution is further provided, the bath tank is provided with a fluid inlet and a fluid outlet, and the fluid inlet and the fluid outlet are the same. The electroplating system according to Application Example 9 coupled to an anode chamber recirculation loop.</u><u style="single">[Application Example 11] The electroplating system according to Application Example 10, wherein the oxygen removing device includes a degassing device set in the anode chamber recirculation loop upstream of the anode chamber and downstream of the bath tank.</u><u style="single">[Application Example 12] A fluid inlet entering the cathode chamber, a fluid outlet exiting the cathode chamber, the fluid inlet and the fluid outlet of the cathode chamber are connected, and the fluid inlet and the fluid outlet of the bath tank are also connected. Application Example 10 further comprising a connected cathode chamber recirculation loop, wherein the cathode chamber recirculation loop is configured such that the electrolyte solution flows into the cathode chamber while the substrate is electroplated with nickel. Electroplating system described in.</u><u style="single">[Application Example 13] The oxygen scavenging device includes a degassing device arranged in the anode chamber recirculation loop located upstream of the anode chamber and downstream of the bath tank.</u><u style="single"> The degassing device is not provided in the cathode chamber recirculation loop.</u><u style="single"> The electroplating system according to Application Example 12.</u><u style="single">[Application 14] Further comprising a filter installed in the anode chamber recirculation loop upstream of the anode chamber and downstream of the oxygen scavenger and the bath tank, the filter removes particles from the electrolyte solution. The electroplating system according to Application Example 9 configured as described above.</u><u style="single">[Application Example 15] The electroplating system according to any one of Application Examples 1 to 8, wherein the oxygen removing device includes a device for sparging the electrolyte solution with a gas having substantially no oxygen. ..</u><u style="single">[Application Example 16] The electroplating system according to any one of Application Examples 1 to 8, further comprising a pH meter configured to measure the pH of the electrolyte solution.</u><u style="single">[Application Example 17] The electroplating system according to Application Example 16, further comprising a logic circuit for operating the oxygen scavenger in response to a value output by the pH meter.</u><u style="single">[Application Example 18] The electroplating system according to any one of Application Examples 1 to 8, further comprising an oxygen sensor configured to measure the oxygen concentration in the electrolyte solution.</u><u style="single">[Application Example 19] The electroplating system according to any one of Application Examples 1 to 8, and further.</u><u style="single"> With a board electrical contact configured to supply a bias voltage to the board while the board is held in the board holder;</u><u style="single"> With a counter electrode electrical contact that is configured to supply a bias voltage to the counter electrode while in contact with the counter electrode;</u><u style="single"> With an acid generating surface configured to generate free hydrogen ions in the electrolyte solution when a sufficient positive bias voltage is supplied to the counter electrode electrical contact.</u><u style="single"> A negative bias voltage with respect to the counter electrode electrical contact portion is supplied to the substrate electrical contact portion sufficiently to reduce nickel ions from the electrolyte solution and plate the substrate surface, and the counter electrode electrical contact portion is provided. A positive bias voltage was supplied to the acid-generating surface enough to generate free hydrogen ions on the acid-generating surface, thereby lowering the pH of the electrolyte solution. With one or more power units</u><u style="single"> Equipped with an electroplating system.</u><u style="single">[Application Example 20] The electroplating system according to Application Example 19, wherein the free hydrogen ions are generated on the acid generating surface by electrolysis of water molecules in the electrolyte solution.</u><u style="single">[Application 21] The acid generating surface is</u><u style="single"> With a body containing a conductive and corrosion resistant material that does not substantially corrode in the electrolyte solution;</u><u style="single"> A coating on the body that comprises either platinum or one or more metal oxides selected from oxides of platinum, niobium, ruthenium, iridium, and tantalum.</u><u style="single"> The electroplating system according to Application Example 19, which includes.</u><u style="single">[Application 22] The electroplating system according to Application 21, wherein the conductive and corrosion resistant material is titanium, tantalum, niobium, or zirconium.</u><u style="single">[Application Example 23] An acid generation bath tank having a fluid inlet and a fluid outlet, which is designed to hold a certain volume of the electrolyte solution and has the acid generation surface installed inside. ;</u><u style="single"> The fluid outlet of the acid generation bath tank is fluidly connected to the fluid inlet of the anode chamber and / or the fluid inlet of the cathode chamber, and the fluid inlet of the tank is connected to the fluid outlet of the anode chamber and / or the fluid outlet of the cathode chamber. With a fluid-connected, acid-generating bath tank recirculation loop;</u><u style="single"> With</u><u style="single"> The counter electrode electrical contact is further configured to supply a bias voltage to the counter electrode installed in the acid generating bath tank;</u><u style="single"> While the electrolyte solution circulates through the recirculation loop of the acid-generating bath tank, the pH of the electrolyte solution flowing through the fluid outlet of the tank is lower than that of the electrolyte solution flowing through the fluid inlet of the tank.</u><u style="single"> The electroplating system according to Application Example 19.</u><u style="single">[Application Example 24] The electroplating system according to any one of Application Examples 1 to 8, wherein the porous separator is a porous membrane having substantially no ion exchange site.</u><u style="single">[Application Example 25] A porous separator between a nickel anode, a cathode chamber, and an anode chamber and the cathode chamber, which allows an ionic current to pass through electroplating but blocks the passage of an electrolyte solution. A method of electroplating nickel on a semiconductor substrate in an electroplating tank having the anode chamber containing a separator.</u><u style="single"> Reduce the oxygen concentration in the electrolyte solution to about 1 PPM or less;</u><u style="single"> The electrolyte solution with reduced oxygen concentration is poured into the anode chamber;</u><u style="single"> The electrolyte solution with reduced oxygen concentration is brought into contact with the nickel anode in the anode chamber;</u><u style="single"> Nickel from the electrolyte solution is electroplated onto the substrate in the cathode chamber.</u><u style="single"> A method of maintaining the pH of the electrolyte solution in the cathode chamber at about 3.5 to 4.5.</u><u style="single">[Application 26] Further, the electrolyte solution is allowed to flow into the cathode chamber;</u><u style="single"> The oxygen concentration in the electrolyte solution flowing through the anode chamber is lower than the oxygen concentration in the electrolyte solution flowing through the cathode chamber.</u><u style="single"> The method described in Application Example 25.</u><u style="single">[Application Example 27] The method according to Application Example 25, wherein the oxygen concentration in the electrolyte solution is lowered to about 0.5 PPM or less.</u><u style="single">[Application Example 28] The method according to Application Example 25, wherein the temperature of the electrolyte solution during electroplating is higher than about 40 degrees Celsius.</u><u style="single">[Application Example 29] The method according to Application Example 25, in which the electrolyte solution is degassed when the oxygen concentration in the electrolyte solution is lowered.</u><u style="single">[Application Example 30] The method according to Application Example 25, wherein when lowering the oxygen concentration in the electrolyte solution, the electrolyte solution is sparged with a gas having substantially no oxygen.</u><u style="single">[Application Example 31] The method according to Application Example 30, wherein the gas having substantially no oxygen is an inert gas.</u><u style="single">[Application Example 32] The method according to Application Example 31, wherein the inert gas contains nitrogen and / or argon.</u><u style="single">[Application 33] The pH of the electrolyte solution in the electroplating tank is sensed;</u><u style="single"> Send an alert if the sensed pH is above about 4.5</u><u style="single">The method according to any one of application examples 25 to 32.</u><u style="single">[Application 34] The pH of the electrolyte solution in the electroplating tank is sensed;</u><u style="single"> If the sensed pH is above about 4.5, the oxygen concentration in the electrolyte solution is further reduced before the electrolyte solution flows into the anode chamber.</u><u style="single"> The method according to any one of application examples 25 to 32.</u><u style="single">[Application 35] Sensing the oxygen concentration of the electrolyte solution in the anode chamber;</u><u style="single"> If the sensed oxygen concentration is above about 1 PPM, the oxygen concentration in the electrolyte solution is further reduced before the electrolyte solution flows into the anode chamber.</u><u style="single"> The method according to any one of application examples 25 to 32.</u><u style="single">[Application Example 36] While electroplating nickel from the electrolyte solution onto a semiconductor substrate in an electroplating tank having an anode chamber and a cathode chamber, before the electrolyte solution flows into the anode chamber of the electroplating tank. A method of preventing the pH of the electrolyte solution from rising above about pH 4.5 by lowering the oxygen concentration in the electrolyte solution to about 1 PPM or less.</u>