Vaporizer delivery ampoule

Field of invention The present invention relates to evaporators, more particularly in liquids and solids such as liquid and solid source reagents used in chemical vapor deposition (CVD), atomic layer chemical vapor deposition (ALCVD) and ion injection. The present invention relates to an evaporator delivery system having a large number of containers that provide an expanded surface area for material evaporation.

Description of related technology Chemical vapor deposition (CVD) has been widely used in semiconductor wafer processing for film and film pretreatment. CVD is, in many respects, the preferred deposition method because of its ability to provide highly conformal, high quality films, for example, at relatively fast processing times. In addition, CVD is beneficial for coating irregularly shaped substrates, including providing highly conformal films, even for deep contacts and other openings.

Generally, the CVD technique involves delivering a gaseous reactant to the surface of a substrate on which a chemical reaction takes place under temperature and pressure conditions suitable for the thermodynamics of the desired reaction. The type and composition of layers that can be formed using CVD is limited by the ability to deliver the reactant or reaction precursor to the surface of the substrate. Various liquid reactants and precursors have been successfully used in CVD applications by delivering the liquid reactants in carrier gases. In a liquid reactant CVD system, the carrier gas is typically bubbled through the container of the liquid reactant at a controlled rate to saturate the carrier gas with the liquid reactant and then the saturated carrier. Is transferred to the reaction chamber. Similar attempts have been made to deliver solid reactants to the CVD reaction chamber, but with little success. Delivery of the solid precursor in the CVD process is carried out using the sublimator / bubbler method, in which the precursor is usually placed in a sublimator / bubbler tank, which tank is then used as the precursor. Heated to the sublimation temperature of the body, the precursor is converted to a gaseous compound, which is transferred to the CVD reactor along with carrier gases such as hydrogen, helium, argon or nitrogen. However, this procedure has not been successful for many reasons in reliably and reproducibly delivering solid precursors to the reaction chamber. The main problem with this technique is the inability to consistently evaporate the solid at a controlled rate such that the reproducible flow of the evaporated solid precursor can be delivered to the processing chamber. Also, it is difficult to guarantee complete saturation of the rapidly flowing carrier gas stream. This is because the amount of exposed surface area of the solid precursor in the evaporator system is limited and there is a lack of uniform temperature for maximum sublimation.

Similar problems are inherent in conventional ion implantation systems that include an ion source in which the dopant element is ionized and then accelerated to form an ion beam directed at the workpiece surface for implantation. Is. When a solid dopant material is used, it is generally placed in an evaporator for heating and the subsequent vapor formed is transferred inside the ion source for ionization and subsequent ion beam formation.

While solid ion source materials are highly favored for safety reasons, solid semiconductor dopants have presented serious technical and operational problems. For example, the use of solid precursor materials in evaporators causes increased downtime for instruments, deterioration of product quality and accumulation of deposits in the evaporator.

Prior art evaporator systems have a number of inconveniences, including the accumulation of condensed material within the evaporator and the formation of "cold spots" within the evaporator due to the lack of uniform heating in the evaporator. .. Accumulation of unwanted deposits is exacerbated in evaporator systems that require internal movable surfaces for rotating individual vials and / or wells of source material. These internal mechanisms create additional "cold spots" within the evaporator, leading to further deposition of evaporated material. Moreover, the operation of these evaporators is neither efficient nor reliable due to the accumulation of deposits on the internal moving mechanism. The drawbacks of prior art evaporators are particularly pronounced for temperature sensitive solid source materials with low vapor pressure. Thus, it is difficult to evaporate the solid at a controlled rate so that the reproducible flow of the evaporated solid precursor can be delivered to the downstream deposition system.

<p> Therefore, thermal dissociation of the source material, inoperability of internal moving parts due to accumulation of deposits in the evaporator, condensation of low vapor pressure compounds due to "cold points" in the evaporator and / or inconsistent vaporization to downstream deposition systems. Evaporators that efficiently evaporate solid and / or liquid chemical sources without the inconveniences associated with prior art, such as flow, are needed in the art.</p>

<p>Outline of the invention The present invention relates to evaporator systems and methods for evaporating solid and liquid chemical sources of particular utility for semiconductor manufacturing applications.</p><p> In one embodiment, the invention relates to a vapor delivery system for evaporation and delivery of source material that provides a sufficient surface area with a uniform carrier gas flow that meets the flow rates required for typical deposition applications. , This steam delivery system a) With at least one container for holding the evaporative source material, b) Multiple perforated protrusions placed in the container, with perforated protrusions that provide a passage for the evaporative source material to pass through. c) A carrier gas tube that introduces a carrier gas stream to pass through the container, To be equipped.</p><p> In another aspect, the invention provides a steam delivery system for evaporation and delivery of precursors, which steam delivery system. a) An ampoule that includes an ampoule bottom, a side wall, and a removable upper end to form an internal ampoule chamber. b) With the gas inlet and gas outlet connected to the ampoule, c) At least one container located in the internal ampoule chamber, including the bottom and side walls of the container and forming the container cavity. d) A plurality of perforated protrusions located at least at the bottom of the vessel and providing passage through the bottom of the vessel, with perforated protrusions extending into the vessel cavity. To be equipped.</p><p> The precursor may include a solid or liquid source material, as fully described below. Precursors are, but are not limited to, decaborane, boron, phosphorus, gallium, indium, copper, antimony, hafnium tetrachloride, zirconium tetrachloride, arsenic, indium trichloride, organometallic β-diketone complex, cyclopentadienyl. Must be a solid precursor such as cycloheptatrienyl-titanium (CpTiCht), aluminum trichloride, titanium iodide, cyclooctatetraenecyclo-pentadienyl titanium, biscyclopentadienyl titanium diazide, tungsten carbonyl. Is preferable.</p><p> In yet another aspect, the present invention relates to an evaporator that can be easily inserted into a conventional ampoule with minimal retrofitting of processing tools. a) Multiple vertically stacked containers, each of which has a cavity for holding the source material, b) Multiple perforated protrusions located in each of the vertically stacked containers and extending into each of the respective cavities through which the carrier gas passes between the adjacent and vertically stacked containers. With a perforated protrusion forming a passage for c) A carrier gas tube that contacts multiple vertically stacked containers and extends through the cavities of each vertically stacked container. To be equipped.</p><p> In a further aspect, the invention provides an evaporator, which is an evaporator. a) An ampoule that has an ampoule bottom and an ampoule side wall to form an inner chamber, b) The upper end of the ampoule that seals the inner chamber and c) Gas inlets and outlets connected to the upper end of the ampoule, d) Multiple vertically stacked and in contact containers placed in the inner chamber, each containing the bottom of the container and the side wall of the container, forming a container cavity for holding the solid precursor material. And each container side wall is in contact with the ampoule side wall, e) Multiple perforated protrusions located at the bottom of each vessel and providing passages between containers that are close, vertically stacked and in contact with each other and that extend into the vessel cavity. , f) A carrier gas immersion tube that is located in the inner chamber and communicates with the gas inlet to guide the carrier gas under the vertically stacked and in contact container. g) Means for heating ampoules, To be equipped.</p><p> In another aspect, the present invention relates to a container comprising a plurality of tapered protrusions, the tapered protrusion having a conical hole that narrows as the tapered protrusion extends into the container cavity. ing. This configuration of the protrusions provides a substantially unidirectional flow of carrier gas through multiple vertically stacked containers located within the ampoule.</p><p> In yet another aspect, the invention provides a method for evaporating a source material and delivering it to a downstream process chamber, which method is: a) To provide multiple interconnected and vertically stacked containers containing evaporative source material within themselves, each of which is a plurality of aisle protrusions. To include and b) Place interconnected and vertically stacked containers in sealable ampoules. c) Applying heat to the sealable ampoule in an amount sufficient to evaporate the source material in the sealable ampoule. d) Introducing carrier gas into the sealable ampoule to transfer the evaporated source material through the sealable ampoule to the process chamber. including.</p><p> Other aspects and features of the invention will become more fully apparent from the claims that follow.</p>

Detailed description of the invention and preferred embodiments of the invention The present invention is based on the following findings. That is, certain source materials used in evaporator systems are not properly evaporated in sufficient quantities to meet the flow rates required for typical deposition applications. In some cases, high temperatures above 200 ° C were used to increase the rate of sublimation that could cause decomposition of the source material in order to achieve the required flow rate.

The evaporator shown in FIG. 1 according to one embodiment of the present invention overcomes the defects of the evaporator according to the prior art. This evaporator delivery system 10 is made of suitable heat conductive materials such as silver, silver alloys, copper, copper alloys, aluminum, aluminum alloys, lead, nickel clad, stainless steel, graphite and / or ceramic materials. Alloy 12 is included. The ampoule includes a bottom 14 and a side wall 16 that form the interior chamber. The ampoule can have any shape that facilitates a uniform flow of carrier gas through the ampoule, such as the cylindrical shape shown. The preferred shape of the ampoule base is a cylindrical shape machined to a very tight tolerance that allows only 1/1000 to 3/1000 1 inch gaps for precisely machined containers. Mounting the vessel requires the walls to be very parallel, to ensure that each side wall of the vessel has good thermal contact with the inner wall of the ampoule base. As you can see, due to the strict tolerances required to ensure even contact between the container and the inner wall of the ampoule, the container unit installation and removal process involves the base and container to allow easy installation. Each may require heating and / or cooling.

The carrier gas inlet 20 is located at the upper end 18 of the ampoule and is preferably communicated with the ampoule in order to introduce the carrier gas into the ampoule.

A plurality of vertically stacked containers 22 are arranged in the inner chamber of the ampoule. The stacked containers are separable from each other and removable from the ampoule for easy cleaning and refilling. The internal carrier gas member 23 is located in the ampoule, which is connected (welded) to the carrier gas inlet 20 and is the bottom of the inner chamber and the bottom of the vertically stacked container. Guide the carrier gas under the container. In FIG. 1, the internal carrier gas member 23 passes through each container cavity 27 (shown in FIG. 3) and the container bottom 24. However, to ensure leak-free sealing where the internal carrier gas member intersects the bottom of the container, a sealing O-ring 38 (shown in FIG. 5) is used in the container, especially if the source material is liquid. It should be understood that it may be placed in between. It is also conceivable to add an outer O-ring to seal between the containers on the upper end surface of each container (tray) side wall.

Also, depending on the solid precursor, it may be necessary to stop the entrainment of solids in the carrier gas flow. High-purity stainless frit (probably pore diameter 1-100 microns) can adhere at any position in the carrier gas flow rate. The frit can attach to the "entrance" of each protrusion, and a large disc-shaped frit attaches to the top tray and is trapped in the top tray by the pressure of installing the lid on the ampoule, or at the exit. May adhere to gas flow passages.

As shown in FIG. 3, the individual vessels 22 each include a bottom 24 and a side wall 26 to form a vessel cavity 27 for placing the preferred source material 28. The container is preferably made of a non-reactive heat conductive material such as silver, silver alloy, copper, copper alloy, aluminum, aluminum alloy, lead, nickel clad, stainless steel, graphite and / or ceramic material.

Each of the individual containers includes a plurality of protrusions 30, and each protrusion includes a passage 32 for the carrier gas to move through the protrusions. The shape of the protrusion may be any configuration that provides for easy gas flow through it. The protrusions are preferably cylindrical or conical in shape, for example as shown in FIGS. 3 and 4.

FIG. 4 shows a protrusion 30 having a substantially funnel-like configuration with conical holes, which taper as the tapered protrusion extends into the vessel cavity 27. The conical holes provide the passage of carrier gas from the adjacent lower vessel through the larger hole opening 34 into the vessel cavity (smaller hole 36), while the lower proximity vessel of the carrier gas. Reduce backflow to. Importantly, maintaining unidirectional flow through stacked vessels enhances the transfer of carrier gases saturated with evaporated source material at the flow rates required by many semiconductor processing systems. .. As the carrier gas, including the evaporated source material, moves upward from the bottom of the ampoule through the tapered protrusion, a swirling effect occurs in which the gas molecules are pressed against the wall of the protrusion. This swirl effect causes the vaporized source material to move rapidly through the protrusion while contacting the heated wall of the tapered protrusion. Thus, the evaporated source material can maintain contact with the heated vessel and cause precipitation of the evaporated material, and / or cold points that can clog the passages at the protrusions. Accompanied by an incidental reduction in.

The overhang can be an extension mounted on the surface of the vessel, such as a commercially available perforated stainless steel screw, for adjustability to optimize the process or sublimation rate. Alternatively, the protrusions are integrally formed as part of the bottom of the vessel, allowing maximum heat transfer to these protrusions. The height of each of the protrusions is preferably approximately the same as or lower than the height of the side wall of the container. The height of each protrusion is lower than the height of the side wall of the vessel, so that it is more preferred to provide a head gap above the end of the protrusion for gas dispersion and circulation within each vessel. Alternatively, the vessel and protrusion can be configured to create a fluidized bed for each vessel. Since the carrier gas flow can enter the vessel from below the solid surface, it is understood that the pore size is sufficient to hold the solid precursor in each vessel shown in FIG. Another embodiment relates to a protrusion having a side wall that includes a hole in itself to deliver carrier gas through the solid precursor for fluidization of the solid precursor, such as that shown in FIG.

The overhang is high enough to provide a leak-free area for placing a sufficient amount of source material, either liquid or solid, and is below through the open hole 32 of the overhang without causing a leak. The container should be supplied with the required evaporated material. Each protrusion is preferably stretched from about 0 mm to about 5 mm, more preferably from about 1.5 mm to about 3.0 mm, perpendicular to the bottom of the container.

As shown in FIG. 1, the position of the overhangs in each vessel is slightly offset from the overhangs of the adjacent vessels so that the carrier gas circulates within the vessel to contact the evaporated source material. And then transferred to the next level container through the overhang. Advantageously, the carrier gas contacts at multiple levels and the evaporator system has an increased amount of source material, resulting in carrier gas saturation at an enhanced rate.

The size of the evaporator delivery system 10 depends on the amount of evaporative gas supplied to the downstream CVD equipment or ion implantation system. The size of the evaporator generally corresponds to a cylinder with an inner diameter of about 3-6 inches, preferably about 3.75 inches. The amount of containers, including stacked containers, is determined by the size of the evaporator, and it is preferable to seal 3 to 5 containers in an ampoule.

Ampoules of the invention, including multiple inner containers, can be heated to a desired temperature according to the type and supply of source material, the concentration of evaporative gas and other operating conditions. The heating can be carried out using a ribbon heater wrapped around the evaporator or a block heater having a shape covering the evaporator, or by circulation of hot air or a liquid heat medium. The heating method is not particularly limited as long as the evaporator is heated and kept at a desired temperature accurately. Ampoules are preferably heated from the side walls relative to the bottom to reduce the following possibilities: That is, it is possible that the lower vessel sublimates at a higher temperature and forms a cooler upper vessel that can result in possible condensation, which can result in clogging. The preferred heat transfer is from the side wall of the ampoule to the side wall of the vessel. Preheating of the carrier gas may also be required, depending on the heating method, the length of the inlet tube of the heated carrier gas and the flow rate of the carrier gas.

Advantageously, the evaporator delivery system of the present invention provides a series of heated containers, which further provide a plurality of heated protrusions that increase the heated surface area, thereby providing a plurality of heated protrusions. The increased heat distribution allows the sublimation of solid source materials. It may be desirable for ampoules to have a large amount of heat to provide and maintain a more consistent temperature during processing. The present invention was designed with a large amount of heat, which is based on the fact that heat is required to sustain the sublimation of the solid source material from the solid state to the vapor state. At a given temperature, the vapor pressure of a solid is the partial pressure of its material at the interface. That is, in a given period, as many molecules as there are molecules sublimating from the surface condense on the solid surface. Equilibrium is disrupted when molecules in the gaseous state are removed from the solid / gas interface by carrier gas. Obviously, if sufficient heat is supplied to the solid surface to supplement the latent heat of sublimation, sublimation occurs at a faster rate to restore equilibrium. By providing multiple heated protrusions, the entire conduction vessel acts as a heated surface, thereby increasing the sublimation rate and increasing the flow rate of the saturated carrier gas, with passaged protrusions. Reduces precipitation of evaporated source material that can clog.

The temperature of the evaporator depends on the operating conditions of the downstream CVD equipment or ion implantation system, as well as the vapor pressure and the amount of source material. The temperature is generally about 40 to about 300 ° C.

The evaporator delivery system of the present invention further includes a line for supplying the carrier gas and moving the evaporator connected to the evaporator, and a regulating valve and an instrument for measuring pressure and temperature. A heater may be provided to maintain temperature in the gas supply line and in the line that moves the evaporated material to the downstream semiconductor manufacturing process chamber. It is desirable to make the downstream line 5-10 ° C higher than the ampoule to prevent condensation on the line.

Methods utilizing the evaporator system of the present invention include introducing the source material into a container and then stacking the containers in an ampoule. The source material may be a solid, a liquid or a solid dissolved in a solvent. In addition, the source material may be coated on the surface of the vessel and protrusions in the vessel cavity in the form of a film by any of a variety of methods, in which the metal complex is melted and dissolved by heating. A method is included in which the metal complex is applied to the support and then cooled. Further, the metal complex can be dissolved in a solvent and applied to the surfaces of the container and the protrusion, and then the solvent can be removed under reduced pressure. When different source materials will be used in the downstream treatment system, the present invention provides the ability to introduce different source materials into different containers of vertically stacked containers.

The evaporator unit 44 shown in FIG. 5, which includes a plurality of vertically stacked containers in contact with the internal gas carrier member 23, is arranged in an ampoule. The ampoule top lid 18 (shown in Figures 1 and 2) is located at the top of the conductive ampoule, and the O-ring element (the O-ring may be made of Teflon, elastomer or metal seal) and / Alternatively, it is tightened to the ampoule by a mechanical fixture such as a screw. Means for heating the ampoule are coupled and the internal temperature inside the ampoule and the container in contact is raised to a temperature sufficient to evaporate the sealed source material. The sublimation rate will be maximum in the first or lowest container. This is because the tray contains pure carriers, while the container above it contains partially or completely saturated carrier gas. Therefore, it may be necessary to place more precursors in the bottom vessel and / or increase the height dimension of the vessel to allow for more uniform surface area throughout the life of the ampoule in the process tool. There is.

The solid used as the source material evaporates through the sublimation process, which heats the walls of the conductive ampoule, which is preferably in contact with multiple vertically stacked vessels made of conductive material. Achieved by. The sublimation process involves converting a solid, such as Decaborane, from a solid state to a vapor state without entering an intermediate liquid state. The present invention is characterized by any suitable solid source material, eg, sublimation temperature in the range of about 20 ° C to about 300 ° C, and about 10.^-2Toru ~ about 10³It is efficient when used with solid materials that have a vapor pressure in the torr range.

Temperatures include, but are not limited to, strip heaters, radiant heaters, heated enclosures, circulating fluid heaters, resistance heating systems, induction heating systems, etc. assembled and configured for controlled temperature manipulation. It may be controlled in the evaporator by any thermal control system. In addition, the temperature within the ampoule can be detected by a thermocouple, thermistor, or any other suitable temperature sensing joint or device configured to contact the surface of the heat conductive ampoule and / or vessel.

To determine when the source material is exhausted from the container, we are considering a level sensor monitoring system that determines the amount of solid or liquid in the top and / or bottom trays. An optical sensor that communicates with a reflective surface on the bottom of the container and causes a signal change when the container is almost empty or empty.

FIG. 6 shows a simplified evaporator delivery system 66 for supplying carrier gas to the evaporator 10. The carrier gas source 64 is connected to the evaporator 10 to supply the carrier gas. In the alternative mode of introducing the source material, the liquid source material may be introduced from the liquid source container 67. The flow rate of the carrier gas may be monitored and controlled by a flow meter 68, which is located on the carrier gas delivery line and the line that transfers the evaporated source material to the processing chamber 70. The gas delivery line is preferably manufactured from a material having a low coefficient of friction, such as a polymer, in consideration of high flow rate. The evaporator delivery system is preferably made of a heat conductive material that provides the transmission of thermal energy generated by at least one heating means 72 communicated with the evaporator unit 10.

The amount of power required for complete evaporation is a function of the chemistry of the source material and carrier gas and the flow rate of their mixture. According to the present invention, the thermal power transferred to the evaporator is between about 100W and about 3000W to provide the optimum homeothermic temperature. Thus, the heating power absorbed by the flowing mixture is a small portion of the available heating power. Therefore, the power absorbed by the gas vapor is a trivial disturbance to the available heating power, and it is possible to substantially maintain the ideal constant temperature of the conduction heating surface.

In operation, the precursor source material is preferably placed in a drying box or glove box and loaded into the container unit to eliminate the reaction of the precursor with oxygen and moisture while the ampoule is open. The carrier gas from the gas source 64 is introduced into the evaporator unit from the gas inlet 20 with a gas flow of 1 sccm to about 500 sccm. The carrier gas is transferred into the evaporator at a pressure that provides a stable flow of carrier gas, which is pushed through the protrusions of the vertically stacked vessels. Since the carrier gas travels upward through different levels of vertically stacked vessels, the carrier gas is saturated with the evaporated source material and transferred from the evaporator unit to the process chamber 70 at the gas outlet valve 40. Will be done.

The advantages of the present invention are more fully illustrated with reference to the following examples.

Example 1 The evaporator of the present invention including a container unit having five containers stacked in the ampoule of the present invention as shown in FIG. 1 was tested to determine the effectiveness of thermal conductivity from the ampoule to the container. The ampoule was made of good quality stainless steel and connected to a block heater that had a snug shape around the ampoule. The heater was connected to a variable transformer that was a variable AC voltage source and controlled the degree of heating. Some of the individual vessels placed in the ampoule, namely vessels 1 and 5, were connected to temperature sensors to determine the uniformity of heating and the effectiveness of heat transfer from the ampoule to the vessel. An ampoule was connected to a source of carrier gas that was introduced into the ampoule and passed through the vessel unit at about 500 sccm. As shown in FIG. 7, as the temperature of the heater mounted on the ampoule increased, so did the internal temperature detected in the vessel, depending on the effectiveness of heat conduction. The temperatures detected in vessels 1 and 5 were comparable to the temperature of the ampoules, indicating uniformity of heating through the stack of vessels. Thus, the individual vessels provide an additional surface area that is uniformly heated to evaporate the precursor material.

FIG. 8 shows the distribution of heat from the ampoule to the protrusions located in the container 5. The temperature was raised to 130 ° C and the heat distribution within the ampoule was nearly constant after the first hour of evaporation. The large number of vessels provides an increased area for placing the precursor material, allowing more products to be manufactured without refilling the ampoules, thereby reducing instrument off-time.

<figref num="1">It is a perspective view of the evaporator by one Embodiment of this invention.</figref><figref num="2">It is a top view of a plurality of perforated protrusions arranged in a container arranged in an ampoule according to the present invention.</figref><figref num="3">It is a side view of the container which shows the plurality of cylindrical protrusions of this invention.</figref><figref num="4">It is a side view of the container which shows the plurality of conical protrusions of this invention.</figref><figref num="5">It is a side view of the plurality of vertically stacked containers of this invention.</figref><figref num="6">It is a simplified schematic diagram of the evaporator delivery system of this invention.</figref><figref num="7">It is a graph which shows the result of detecting the temperature in a container unit as a carrier gas flows through an ampoule of this invention while heating an ampoule.</figref><figref num="8">It is a graph which shows the result of heating the ampoule and detecting the temperature in the container unit and the protrusion in the ampoule of the present invention.</figref><figref num="9">FIG. 5 is a side view of a container showing a plurality of conical protrusions including side holes.</figref><figref num="10">An alternative embodiment of the present invention is shown.</figref>