Scheme for copper filling in vias and trenches

BACKGROUND OF THE INVENTION

00011. Field of the Invention

0002Embodiments of the present invention generally relate to methods and apparatuses using supercritical fluids and/or dense fluids in semiconductor applications. More particularly, embodiments of the present invention relate to methods and apparatuses using supercritical fluids and/or dense fluids for material deposition.

00032. Description of the Related Art

0004Copper and its alloys have become the metals of choice for sub-micron interconnect technology because copper has a lower resistivity than aluminum, (1.7 μΩ-cm compared to 3.1 μΩ-cm for aluminum), and a higher current carrying capacity and significantly higher electromigration resistance. These characteristics are important for supporting the higher current densities experienced at high levels of integration and increased device speed. Further, copper has a good thermal conductivity and is available in a highly pure state. One problem with the use of copper is that copper diffuses into silicon, silicon dioxide, and other dielectric materials which may compromise the integrity of devices. Tantalum nitride, for example, has been used as a barrier material to prevent the diffusion of copper into underlying layers. However, tantalum nitride and other barrier material layers are poor wetting agents, which may cause numerous problems, for a copper material layer to deposit thereon.

0005Vapor deposition processes, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), have played an important role in copper metallization to deposit materials on substrates. Copper materials deposited by PVD generally provide good adhesion to barrier materials and a typical fabrication process includes depositing a barrier layer over a feature, physical vapor depositing a copper seed layer over the barrier layer, and then electroplating a copper conductive material layer over the copper seed layer to fill the feature. Finally, the deposited layers and the dielectric layers are planarized, such as by chemical mechanical polishing (CMP), to define a conductive interconnect feature.

0006However, inherent PVD limitations, such as poor conformality, are potential road-blocks for filing copper materials into interconnect features. The non-conformal problem can be especially severe in overhangs at the trench or via openings of a copper interconnect. As the geometries of electronic devices continue to shrink and the density of devices continues to increase, the size and aspect ratio of the features are becoming more aggressive, e.g., feature sizes of 0.07 μm and aspect ratios of 10 or greater. Accordingly, conformal deposition of materials to form these devices is becoming increasingly important.

0007Alternatively, CVD provides conformal material deposition for devices with high aspect ratios and shrinking geometries. However, a CVD-deposited copper seed layer may agglomerate and become discontinuous, and in turn, prevent uniform deposition of a subsequent copper conductive material layer over the copper seed layer. In addition, the conformality of a CVD-deposited copper seed layer may be a disadvantage for complete fill of trenches and other features, when the densities of the features vary over the surface of the substrate. As a result, forbidden gaps, where small features and trenches in dense area are filled but large feature and trenches in less dense area are not completely filled, may be formed and such incomplete fillings of features tend to become worse after subsequent processing by CMP and high temperature thermal stressing, resulting in de-wetting, formation of voids in the copper layer, and electrical failure.

0008Another problem with copper materials deposited by CVD at a relatively low deposition temperature and high deposition rate is that sufficient vapor pressure are required for reaction precursors to chemically decompose and react on the surface of the substrate. Thus, highly volatile copper precursors, such as fluorinated copper precursors, are used. As a result, the CVD deposited copper material often contains contamination materials at the barrier and copper interface, leading to poor adhesion issues.

0009Therefore, there is a need for an apparatus and a method of forming an improved interconnect structure and depositing a metal material on a substrate.

SUMMARY OF THE INVENTION

0010Embodiments of the present invention generally relate to methods and apparatuses using supercritical fluids and/or dense fluids in semiconductor applications. In one embodiment, a metal material layer is deposited by applying a supercritical fluid, a dense fluid, or combinations thereof and a metal-containing precursor to the surface of a substrate inside a substrate processing chamber. In another embodiment, a copper material layer is deposited by applying a supercritical fluid, a dense fluid, or combinations thereof and a copper containing precursor to the surface of the substrate.

0011One method of processing a substrate inside a chamber includes delivering a fluid selected from the group consisting of a supercritical fluid, a dense fluid, and combinations thereof to the surface of the substrate having at least one feature thereon, delivering one or more metal-containing precursor compounds to the surface of the substrate inside the chamber, and depositing a metal material on the surface of the substrate. In addition, a mixture of the fluid and the one or more metal-containing precursor compounds is formed prior to being delivered inside the chamber. Alternatively, a mixture of the fluid and the one or more metal-containing precursor compounds is formed after being delivered inside the chamber.

0012Another method of processing a substrate inside a chamber includes delivering a fluid selected from the group consisting of a supercritical fluid, a dense fluid, and combinations thereof to the surface of the substrate having at least one feature thereon, sequentially delivering at least two different metal-containing precursor compounds to the chamber, and depositing a first metal material and a second metal material on the surface of the substrate.

0013In one embodiment, a copper see layer is formed over a barrier material layer on the surface of a substrate having features thereon. In another embodiment, a first metal material and a second metal material are sequentially deposited and annealing is performed to form a metal alloy material on the surface of a substrate.

0014In still another embodiment, a substrate structure is cleaned and/or dried by applying a supercritical fluid, a dense fluid, or combinations thereof before and/or after the metal material is deposited. Advantageously, substrate processing including deposition, cleaning, among others, can be performed using the same substrate processing chamber.

0015The invention further provides an apparatus for processing a substrate, including a chamber comprising walls defining an enclosure, the chamber adapted to be pressurized to a pressure of at least about 1000 psi, a substrate support disposed within the enclosure, the substrate support having a substrate receiving surface, a fluid delivery device adapted to deliver a fluid selected from the group consisting of a supercritical fluid, a dense fluid, and combinations thereof to the substrate receiving surface, a fluid supply adapted to deliver one or more metal-containing precursor compounds, a fluid line coupled between the fluid delivery device and the fluid supply, and one or more heating elements.

0016In addition, the invention provides a system including one or more first chambers adapted to deliver one or more metal-containing precursor compounds and a fluid selected from the group consisting of a supercritical fluid, a dense fluid, and combinations thereof to the substrate receiving surface and deposit a metal material on the surface of a substrate using a supercritical fluid and/or a dense fluid process, one or more second chambers selected from the group consisting of a wet clean chamber; a dry stripping chamber, a dry etch chamber, and a porous low-k deposition chamber; and combinations thereof, and one or more transfer robots adapted to transfer substrates between the first chambers and second chambers.

BRIEF DESCRIPTION OF THE DRAWINGS

0017So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

0018<figref idref="DRAWINGS">FIG. 1</figref> is a schematic cross-sectional view of one embodiment of a processing chamber adapted to deliver a supercritical fluid and/or a dense fluid to a substrate.

0019<figref idref="DRAWINGS">FIG. 2</figref> is a schematic cross-sectional view of one embodiment of a processing chamber adapted to deliver a supercritical fluid and/or a dense fluid.

0020<figref idref="DRAWINGS">FIG. 3</figref> is a flow chart of one embodiment of an application of depositing a metal material with a supercritical fluid and/or dense fluid.

0021<figref idref="DRAWINGS">FIGS. 4A-4D</figref> are schematic cross-sectional views of one example of a substrate structure at various stages of substrate processing.

0022<figref idref="DRAWINGS">FIG. 5</figref> is a schematic top view of one embodiment of an integrated substrate processing system.

0023<figref idref="DRAWINGS">FIG. 6</figref> is a schematic top view of another embodiment of an integrated substrate processing system.

DETAILED DESCRIPTION OF THE INVENTION

0024Embodiments of the present invention generally relate to methods and apparatuses of employing supercritical fluids and/or dense fluids to deposit a metal material on the surface of a substrate from one or more precursor compounds, such as a metal-containing precursor. In one embodiment, copper materials and other metal materials are deposited as a thin layer with good adhesion to underlying materials on the surface of the substrate to conformally fill features thereon. For example, a copper seed layer is deposited over the surface of a substrate having a barrier material layer thereon using one or more copper-containing precursors and a supercritical fluids and/or dense fluids inside a process chamber.

0025<figref idref="DRAWINGS">FIG. 1</figref> is a schematic cross-sectional view of one embodiment of a processing chamber <b>100</b>, adapted to deliver a supercritical fluid and/or a dense fluid, and one or more precursors, such as a metal-containing precursor to deposit a material on the surface of a substrate, in which the fluids are heated inside the chamber. The processing chamber <b>100</b> includes sidewalls <b>102</b>, a top wall <b>104</b>, and a bottom wall <b>106</b> which define an enclosure <b>108</b>. The processing chamber <b>100</b> may include a slit valve <b>116</b> to provide access for a robot to transfer and receive substrates from the enclosure <b>108</b>. A substrate support <b>112</b> having a platter <b>114</b> thereon is adapted to support a substrate within the enclosure <b>108</b>. The platter <b>114</b> defines a substrate receiving surface for receiving a substrate. In one embodiment, the platter <b>114</b> may be adapted to rotate the substrate during processing.

0026In one embodiment, the volume of the enclosure <b>108</b> includes a small volume to reduce the amount of fluid necessary to fill the enclosure <b>108</b>. For example, the processing chamber <b>100</b> may be adapted to process 300 mm diameter substrates and has a volume of about 10 liters or less, more preferably about 5 liters or less. However, the invention is not limited any specific substrate sizes or substrate types.

0027The processing chamber <b>100</b> may optionally further include one or more acoustic or sonic transducers <b>115</b>. As shown, the transducers <b>115</b> are located on the substrate support <b>112</b> but may be located in other areas of the enclosure <b>108</b>. The transducers <b>115</b> create acoustic or sonic waves directed towards the surface of a substrate to help agitate the fluid. In other embodiments, the transducers may comprise a rod, plunger, or plate located within the enclosure. Other aspects and embodiments of a substrate support adapted to provide sonic agitation are disclosed in co-pending U.S. patent application Ser. No. 09/891,849, filed Jun. 25, 2001 (Publication No. 2002/0029788A1) and in U.S. patent application Ser. No. 09/891,791, filed Jun. 25, 2001 (Publication No. 2002/0063169A1, now abandoned), both of which are herein incorporated by reference in their entirety to the extent not inconsistent with the present disclosure.

0028One or more fluid lines <b>123</b> couple one or more fluid supplies <b>122</b> and one or more fluid inlets <b>124</b> to the processing chamber <b>100</b> (only one fluid line is representatively illustrated in <figref idref="DRAWINGS">FIG. 1</figref>). The one or more fluid lines <b>123</b> and the one or more fluid supplies <b>122</b> are used to provide a supercritical fluid, a dense fluid, a carbon dioxide fluid, a metal-containing precursor, and other fluids, precursors into the processing chamber <b>100</b>. A pump <b>126</b> may be disposed on the fluid lines <b>123</b> between the fluid inlets <b>124</b> and the fluid supplies <b>122</b> for delivering any fluids and precursors, when needed, from the fluid supplies <b>122</b> into the enclosure <b>108</b> of the processing chamber <b>100</b>.

0029One or more heating elements <b>132</b> are disposed proximate or inside the walls <b>102</b>, <b>104</b>, <b>106</b> of the processing chamber <b>100</b> to maintain the temperature inside the processing chamber <b>100</b> to a desired temperature of from room temperature to about 250° C. or higher, suitable for substrate processing, such as substrate cleaning, deposition, post-processing treatment, among others. The heating elements <b>132</b> may comprise resistive heating elements, fluid channels for a heat control fluid, and/or other heating devices. The heating elements <b>132</b> heat the fluid inside the enclosure <b>108</b> to a desired temperature of the heated fluid. The processing chamber <b>100</b> may optionally include cooling elements for rapid cooling of the substrate or the processing chamber.

0030The processing chamber <b>100</b> may optionally include a loop <b>144</b> for re-circulating fluids and precursors to and from the processing chamber <b>100</b>. The loop <b>144</b> may further include a filter <b>146</b>, such as an activated charcoal filter, to help purify the fluids. In one aspect, the loop <b>144</b> helps produce a laminar flow of the fluids within the enclosure <b>108</b> and helps prevent a stagnant fluid bath. It is believed that a laminar flow helps to sweep particles away from the substrate and to prevent particles from re-depositing on the substrate.

0031One or more fluid outlets <b>142</b> are coupled to the processing chamber <b>100</b> for removal of the fluids from the enclosure <b>108</b>. The fluid outlets <b>142</b> may release the fluids to atmosphere, may direct the used fluids to storage, or may recycle the fluids for re-use. As shown, the fluid outlet <b>142</b> is coupled to the fluid supply <b>122</b> to recycle the fluid for re-use. A condenser <b>143</b> may be coupled between the fluid outlets <b>142</b> and the fluid supplies <b>122</b> to condense the fluids prior to being directed to the fluid supplies <b>122</b>.

0032As shown, the fluid inlet <b>124</b> is disposed at a bottom wall <b>106</b> of the processing chamber <b>100</b> while the fluid outlet <b>142</b> is disposed at the top wall <b>104</b> of the processing chamber <b>100</b>. However, the fluid inlet <b>124</b> and the fluid outlet <b>142</b> may be disposed at other areas of the walls <b>102</b>, <b>104</b>, <b>106</b> of the processing chamber <b>100</b>. In addition, the fluid inlet <b>124</b> may be optionally coupled to nozzles, showerhead, or other fluid delivery device to direct the fluid towards the substrate placed inside the processing chamber <b>100</b>.

0033<figref idref="DRAWINGS">FIG. 2</figref> is a schematic cross-sectional view of one embodiment of a processing chamber <b>200</b> adapted to deliver a supercritical fluid and/or a dense fluid, and one or more precursors, such as a metal-containing precursor, to deposit a material on the surface of a substrate, in which the fluids are heated in-line. Some of the parts of the processing chamber <b>200</b> of <figref idref="DRAWINGS">FIG. 2</figref> are similar to the parts of the processing chamber <b>100</b> of <figref idref="DRAWINGS">FIG. 1</figref>. As a consequence, consistent reference numerals have been used for clarity of description where appropriate.

0034The processing chamber <b>200</b> includes one or more heating elements <b>252</b> to heat a fluid line <b>254</b> coupling the one or more fluid supplies <b>122</b> and the processing chamber <b>200</b>. A pump/compressor <b>256</b> may be disposed on the fluid line <b>254</b> to deliver the fluids to the enclosure <b>108</b>. The one or more heating elements <b>252</b> may be disposed before and/or after the pump/compressor <b>256</b>. The fluid line <b>254</b> is coupled to a fluid delivery device <b>258</b>, such as a showerhead, nozzle, or plate, disposed above the substrate support <b>112</b>.

0035The fluid delivery device <b>258</b> may include optional transducers <b>260</b> adapted to create acoustic or sonic waves directed towards the surface of a substrate to help agitate the fluid. In addition, the transducers may be disposed at other locations within the enclosure <b>108</b>. In one embodiment, the substrate support <b>112</b> may be adapted to rotate the substrate and/or the fluid delivery device may be adapted to rotate to help agitate the fluid. The processing chamber <b>200</b> may also optionally include additional heating and/or cooling elements proximate or inside the chamber walls.

0036In one embodiment, one or more precursors and one or more fluids are delivered as a mixture and brought into a supercritical or dense fluid state using the fluid delivery device <b>258</b>, where the mixture contains one or more metal-containing precursor and other precursors dissolved and carried by a supercritical fluid and/or a dense fluid. In another embodiment, one or more precursors and one or more fluids are delivered into the processing chambers <b>100</b>, <b>200</b> into a mixture prior to bringing the mixture into a supercritical or dense fluid state by setting required conditions inside the processing chambers <b>100</b>, <b>200</b>. In still another embodiment, the mixture exists as a supercritical fluid and/or dense fluid state at a partial volume of the enclosure <b>108</b> proximate the surface of the substrate inside the processing chambers <b>100</b>, <b>200</b>. In a further embodiment, a supercritical fluid and/or dense fluid is supplied into the processing chamber until the whole enclosure <b>108</b> is at a supercritical fluid and/or dense fluid state.

0037One or more system controllers are connected to the processing chambers <b>100</b>, <b>200</b> to be adapted to control the functions of various components such as the one or more fluid delivery devices, heating elements, power supplies, substrate supports, lift motors, flow controllers for precursor injection, vacuum pump, robots, and other associated chamber and/or processing functions. The system controllers execute system control software stored in a memory, which in s preferred embodiment is a hard disk drive, and can include analog and digital input/output boards, interface boards, and stepper motor controller boards. Optical and/or magnetic sensors are generally used to move and determine the position of movable mechanical assemblies. One examples of such a processing chamber is described in U.S. application Ser. No. 11/038,456, entitled “Using Supercritical and Dense Fluid in Semiconductor Applications,” by Verhaverbeke, which is assigned to Applied Materials, Inc, the assignee of the present invention. The aforementioned patent application is hereby incorporated by reference to the extent not inconsistent with the disclosure herein. The above processing chamber description is mainly for illustrative purposes, and other processing chambers may also be employed for practicing embodiments of the invention.

0038<figref idref="DRAWINGS">FIG. 3</figref> is a process flow diagram illustrating a method <b>300</b> according to one or more embodiments of the invention. At step <b>310</b>, a substrate for depositing a metal material thereon is positioned on a substrate support inside a chamber. At step <b>320</b>, the surface of the substrate may optionally be cleaned with a supercritical fluid, which can be delivered into the chamber in its supercritical state or, alternatively, formed into its supercritical state inside the chamber. The substrate can be cleaned inside the chamber for a desired processing time, such as about 1 second or larger. Preferably, the cleaning time is between about 5 seconds to about 30 seconds, such as about 10 seconds.

0039The term “supercritical fluid” as used herein refers to a substance above its critical point. The term “dense fluid” as used herein refers to a substance at or below its critical point. Dense fluid preferably includes a substance at or near its critical point. In certain embodiments, a dense fluid includes a substance that is at a state in which its density is at least ⅕, preferably at least ⅓, more preferably at least ½, of the density of the substance at its critical point. Examples of substances, fluids, and/or gases which may be used to advantage as supercritical fluids and/or dense fluids include, but are not limited to, carbon dioxide, xenon, argon, helium, krypton, nitrogen, methane, ethane, propane, pentane, ethylene, methanol, ethanol, isopropanol, isobutanol, cyclohexanol, ammonia, nitrous oxide, oxygen, silicon hexafluoride, methyl fluoride, chlorotrifluoromethane, water, and combinations thereof.

0040For example, supercritical carbon dioxide can be used because of its unique properties as a supercritical fluid and the reduced environmental risks in the use of carbon dioxide. For substances which exhibit supercritical fluid properties, when the substance is above its critical point (critical temperature and critical pressure), the phase boundary between the gas phase and liquid phase disappears, and the substance exists in a single supercritical fluid phase. In the supercritical fluid phase, a substance assumes some of the properties of a gas and some of the properties of a liquid. For example, supercritical fluids have diffusivity properties similar to gases but solvating properties similar to liquids. Therefore, supercritical fluids have good dissolving/cleaning properties and can be used herein to clean the surface of the substrate and/or dissolving one or more precursor compounds.

0041At step <b>330</b>, the substance for forming a supercritical fluid and one or more precursor compounds for depositing a metal material on the surface of the substrate are formed into a mixture and delivered into the chamber. According to one or more embodiments of the invention, the mixture can be formed prior to or after the substance is formed into its supercritical state. For example, a carbon dioxide supercritical fluid may be formed and combined with one or more precursor compounds, where the carbon dioxide supercritical fluid, e.g., serving as a solvent, dissolve the one or more precursors into a solution mixture, which can in turn be delivered into the chamber. Alternatively, carbon dioxide and one or more precursors may be mixed together and formed into a supercritical fluid mixture prior to being delivered into the chamber or directly inside the chamber.

0042Note wishing to be bound by theory, it is contemplated that a supercritical fluid provides good solubility for the one or more precursor compounds, especially for organometallic precursor compounds, such that a broad range of precursor compounds can be solubilized. The solubilized precursor compounds can then be easily adsorbed to the surface of the substrate for depositing a material, such as a metal material, thereon at a desired deposition temperature. Thus, it may not necessary to use highly volatile and toxic precursor compounds which often lead to contamination and toxic waste issues.

0043Exemplary precursor compounds for depositing a metal material, such as copper, may include, but are not limited to, copper (II) bis-hexafluoroacetylacetonate [Cu(hfac)2], 1,5-cyclo-octadiene-copper (I)-hexafluoroacetylacetonate [COD-Cu-hfac], Bis(2,2,7-trimethyloctane-3,5-dionato) copper (II) [Cu(tmod)₂], Bis(2,2,6,6-tetramethyl-3,5-heptanedione) copper (II) [Cu(tmhd)2], Cu(acac)2, Cuhfac(TMVS), Cu(DPM)2, their derivatives, and combinations thereof.

0044Additional exemplary precursor compounds for depositing a metal material, such as nickel (Ni), aluminum (Al), platinum (Pt), palladium (Pd), ruthenium (Ru), manganese (Mn), and magnesium (Mg) may include, but are not limited to, bis(cyclopentadienyl) Ni, Ni(acac)2, Trimethylamine Alane(TEAA), Dimethylaluminum hydride(DMAH), Tri-isobutylAluminum(TIBA), pt(acac)2, Pd(acac)2, pd(C3H5)hfac, Bis(pentamethylcyclopentadienyl) manganese(II), Bis(cyclopentadienyl) manganese(II), Bis(ethylcyclopentadienyl) manganese(II), Bis(tetramethylcyclopentadienyl) manganese(II), Magnesium bis(2,2,6,6-tetramethyl-3,5-heptanedionate) hydrate, Bis(ethylcyclopentadienyl) magnesium, Bis(cyclopentadienyl) magnesium(II), Bis(pentamethylcyclopentadienyl) magnesium, ruthenium beta diketonates, cyclopentadienyl ruthenium, their derivatives, and combinations thereof.

0045In one or more embodiments, the one or more metal-containing precursor compounds delivered by the supercritical fluid may include at least two different metal-containing precursor compounds delivered sequentially to deposit a first metal material and a second metal material. For example, aluminum may be deposited by delivering an aluminum-containing organometallic precursor compound into the chamber before a copper-containing organometallic precursor compound is delivered into the chamber, such as that a metal alloy containing aluminum and copper can be formed, e.g., by annealing the substrate having the two metal materials deposited thereon.

0046In another embodiment, two different metal-containing precursor compounds can be delivered sequentially to deposit a first metal material and a second metal material which may not form alloy. For example, a ruthenium layer can be deposited before a copper layer is deposited, each as a separate layer, without forming into a metal alloy layer.

0047At step <b>340</b>, the temperature inside the chamber is maintained, such as to a temperature that provides the best solubility for the one or more metal-containing precursor compounds, e.g., from room temperature to about 100° C. or higher, or from about 50° C. to about 400° C. or higher. In addition, the pressure inside the chamber is also maintained, such as to a pressure around or above the supercritical pressure for forming a supercritical fluid of the one ore more precursor compounds. The flows of the one ore more precursor compounds are maintained for a deposition time, such as about 5 second or longer, or about 60 seconds or longer.

0048Additionally, a carrier gas, additional reactive gases, and/or an inert gas can be delivered into the chamber. For example, additional reducing agents, such as hydrogen (H2) gas, alcohol type compounds, can be added to react with the metal-containing precursor and reduce the metal state, e.g., reducing Cu²⁺ into Cu⁰, Carrier inert gases, such as argon (Ar), helium (He), nitrogen (N₂), etc., can also be added inside the chamber.

0049At step <b>350</b>, the flows of the one ore more precursor compounds are terminated. For example, the flow of one or more copper-containing precursor is terminated. Optionally, at step <b>360</b>, the surface of the substrate can be cleaned with the supercritical fluid by continuing delivering the one or more fluid after the flows of the one ore more precursor compounds are terminated. The time period for maintaining the flow of the cleaning fluids, such as a supercritical fluid, is about 1 second or larger. Preferably, the time period for the supercritical cleaning fluid is between about 1 second to about 1 minute, such as between about 5 seconds to about 180 seconds, e.g., a time period of about 5 seconds to about 10 seconds. For example, the flow of the supercritical cleaning fluid is continued and re-circulated into the loop <b>144</b> to help removing contaminants, such as residual organic particles, non-reactive metal particles, non-reactive precursor compounds, away from the substrate surface. The contaminants can be further pumped out of the chamber before the remaining supercritical cleaning fluid flow is terminated.

0050At step <b>370</b>, a conformal material layer, such as a conformal metal material layer is deposited on the substrate inside the chamber, and the supercritical fluid is terminated. The deposition of the metal material takes place without the need to vaporize the precursor compounds since the precursor compounds can be solubilized in the supercritical fluid.

0051One example of a method of processing a substrate with a carbon dioxide fluid in the processing chamber <b>100</b> includes transferring a substrate through the slit valve <b>116</b> to the substrate support <b>112</b> and closing the slit valve <b>116</b>. A mixture of carbon dioxide and a copper-containing precursor is pumped by pump <b>126</b> into the processing chamber <b>100</b> from the fluid supply <b>122</b> to a desired pressure for supercritical carbon dioxide within the enclosure <b>108</b>. The fluid inlet <b>124</b> is closed and the heating elements <b>132</b> heat the carbon dioxide to a desired temperature so that the carbon dioxide is at a supercritical fluid state and/or a dense fluid state. The mixture is optionally agitated through application of the transducers <b>115</b> and/or rotation of the substrate. The carbon dioxide supercritical fluid is optionally re-circulated within the enclosure <b>108</b> through the loop <b>144</b>. After the substrate has been processed with the mixture for a desired time period, the fluid outlet <b>142</b> is opened and the carbon dioxide is vented or released to atmosphere, directed to the condenser <b>143</b>, or directed to storage. In one embodiment, releasing the pressure of the chamber causes the carbon dioxide at a supercritical fluid state and/or a dense fluid state to be at a gas state which can be easily removed from the processing chamber <b>100</b>. The substrate may be optionally heated during venting to prevent cooling of the substrate and to prevent moisture uptake. Other methods of processing a substrate with a supercritical fluid and/or dense fluid are also possible in processing chamber <b>100</b>.

0052Another example of a method of processing a substrate with a carbon dioxide fluid in the processing chamber <b>200</b> comprises transferring a substrate to the substrate support <b>112</b>. Carbon dioxide is transferred by pump/compressor <b>256</b> from the fluid supply <b>122</b> through the fluid line <b>254</b> at a desired pressure. The heating elements <b>252</b> heat the carbon dioxide to a desired temperature as the fluid is being transferred though the fluid line <b>254</b>. The fluid delivery device <b>258</b> delivers a supercritical carbon dioxide fluid and/or a dense carbon dioxide fluid to the substrate. The carbon dioxide is optionally agitated through application of the transducers <b>260</b>, rotation of the substrate, and/or rotation of the fluid delivery device. The enclosure <b>108</b> may be pressurized or unpressurized during application of the supercritical carbon dioxide fluid and/or dense carbon dioxide fluid by the fluid delivery device <b>258</b>. In addition, a one or more copper-containing precursors are delivered into the chamber and through the same fluid line or a different fluid line and formed into a mixture with the supercritical carbon dioxide in the fluid line or inside the chamber. After application of the carbon dioxide supercritical fluid and/or the mixture to the substrate, the carbon dioxide is vented or released to atmosphere, directed to the condenser <b>143</b>, or directed to storage. The substrate may be optionally heated during venting to prevent cooling of the substrate and to prevent moisture uptake. Other methods of processing a substrate with a supercritical fluid and/or dense fluid are also possible in the processing chamber <b>200</b>.

0053According to one or more embodiment of the invention, a metal alloy containing a first metal and a second metal can be deposited on the surface of the substrate using at least two different metal-containing precursor compounds. For example, copper alloy can be deposited by co-deposition, where a first metal film is deposited. Exemplary first metal film includes nickel (Ni), aluminum (Al), platinum (Pt), palladium (Pd), etc. before a second metal film, such as copper (Cu) is deposited. Then, annealing can be performed to form a mixed alloy. The deposited copper alloy and other metal alloys can then re-distributed through the entire feature during the higher thermal budget processes, such as post ECP or post CMP.

0054A supercritical fluid can be used to deposit metal material on the surface of a substrate. Because the supercritical fluid has low surface tension, diffusivity of a gas, density of a liquid, a metal film that is conformal, mechanically stronger, adhere well to underlying materials is formed even with the same precursors in comparison to deposition by physical vapor deposition, spin-on, or chemical vapor deposition. It is believed that using a supercritical fluid as a solvent during deposition causes the deposited film to have a lower amount of dangling bond and imperfect cells in comparison to deposition by spin-on or by chemical vapor deposition.

0055<figref idref="DRAWINGS">FIGS. 4A-4D</figref> are schematic cross-sectional views of one example of a substrate <b>400</b> at various stages of semiconductor processing. Supercritical fluids and/or dense fluids, such as a carbon dioxide fluid, are useful in processing of the substrate <b>400</b> at one or more stages of <figref idref="DRAWINGS">FIGS. 4A-4D</figref>, as described further below.

0056<figref idref="DRAWINGS">FIG. 4A</figref> is a schematic cross-sectional view of one embodiment of a substrate <b>400</b> having a dielectric layer <b>202</b> deposited thereon. Depending on the processing stage, the substrate <b>400</b> may be a silicon semiconductor wafer, or other material layer, which has been formed on the wafer. The dielectric layer <b>202</b> may be an oxide, a silicon oxide, carbon-silicon-oxide, a fluoro-silicon, a porous dielectric, or other suitable dielectric formed and patterned to provide a contact hole or via <b>202</b>H extending to an exposed surface portion <b>202</b>T of the substrate <b>400</b>. For purposes of clarity, the substrate <b>400</b> refers to any workpiece upon which film processing is performed, and a substrate structure <b>250</b> is used to denote the substrate <b>400</b> as well as other material layers formed on the substrate <b>400</b>, such as the dielectric layer <b>202</b>. It is also understood by those with skill in the art that the present invention may be used in a dual damascene process flow.

0057<figref idref="DRAWINGS">FIG. 4B</figref> is a schematic cross-sectional view of one embodiment of a barrier layer <b>204</b> formed over the substrate structure <b>250</b> of <figref idref="DRAWINGS">FIG. 4A</figref>, for example, by atomic layer deposition (ALD), chemical vapor deposition (CVD), or physical vapor deposition (PVD). Preferably, the barrier layer comprises a tantalum nitride layer. Examples of other barrier layer materials which may be used include titanium (Ti), titanium nitride (TiN), titanium silicon nitride (TiSiN), tantalum (Ta), tantalum silicon nitride (TaSiN), ruthenium (Ru), tungsten (W), tungsten nitride (WN), tungsten silicon nitride (WSiN), and combinations thereof.

0058<figref idref="DRAWINGS">FIG. 4C</figref> includes depositing a copper seed layer <b>410</b> over a barrier layer <b>204</b> of <figref idref="DRAWINGS">FIG. 4B</figref> using methods and apparatus of the invention. The copper seed layer <b>410</b> formed thereon is very conformal and provides good adhesion to the underlying barrier layer <b>204</b>. The copper seed layer <b>410</b> deposited by the methods and apparatus of the invention may comprise a pure copper material or a copper metal alloy that aids in subsequent deposition of materials thereover. A copper alloy seed layer may comprise copper and a second metal, such as aluminum, magnesium, titanium, zirconium, tin, other metals, and combinations thereof. The second metal preferably comprises aluminum, magnesium, titanium, and combinations thereof and more preferably comprises aluminum. In certain embodiments, the copper alloy seed layer comprises a second metal in a concentration having the lower limits of about 0.001 atomic percent, about 0.01 atomic percent, or about 0.1 atomic percent and having the upper limits of about 5.0 atomic percent, about 2.0 atomic percent, or about 1.0 atomic percent. The concentration of the second metal in a range from any lower limit to any upper limit is within the scope of the present invention. The concentration of the second metal in the copper alloy seed layer is preferably less than about 5.0 atomic percent to lower the resistance of the copper alloy seed layer. The term “layer” as used in the specification is defined as one or more layers. For example, for a copper alloy seed layer comprising copper and a second metal in a concentration in a range between about 0.001 atomic percent and about 5.0 atomic percent, the copper alloy seed layer may comprise a plurality of layers in which the total composition of the layers comprises copper and the second metal in a concentration between about 0.001 atomic percent and about 5.0 atomic percent. For illustration, examples of a copper alloy seed layer comprising a plurality of layers in which the total composition of the layers comprises copper and the second metal in a concentration between about 0.001 atomic percent and about 5.0 atomic percent may comprises a first seed layer comprising the second metal and a second seed layer comprising copper, may comprise a first seed layer comprising a copper/second metal alloy and a second seed layer comprising a copper/second metal alloy, or may comprise a first seed layer comprising a copper/second metal alloy and a second seed layer comprising copper, etc.

0059The copper material layer or copper metal alloy seed layer may be deposited to a thickness of at least about a 5 Å coverage of the sidewalls of the feature or to a thickness of at least a continuous coverage of the sidewalls of the feature. In one embodiment, the copper alloy seed layer is deposited to a thickness at the field areas between about 10 Å and about 2000 Å.

0060<figref idref="DRAWINGS">FIG. 4D</figref> further illustrates depositing a copper conductive material layer <b>420</b> over the copper seed layer <b>410</b> to fill the feature. The term “copper conductive material layer” as used in the specification is defined as a layer comprising copper or a copper alloy. The copper conductive material layer <b>420</b> may be deposited by electroplating, physical vapor deposition, chemical vapor deposition, electroless deposition or a combination of techniques. Preferably, the copper conductive material layer <b>420</b> is deposited by electroplating because of the bottom-up growth which may be obtained in electroplating processes. An exemplary electroplating method is described in U.S. Pat. No. 6,113,771, entitled “Electro Deposition Chemistry”, issued Sep. 5, 2000, and is incorporated herein by reference to the extent not inconsistent with this invention.

0061One embodiment of the invention includes cleaning and/or drying a substrate structure by applying a supercritical fluid and/or a dense fluid thereto. In one embodiment, a carbon dioxide fluid is used at a pressure between about 1,000 psi and about 5,000 psi and a temperature of at least about 31° C. In another embodiment, the carbon dioxide fluid further includes a co-solvent, such as methanol, surfactants, chelating agents, and combinations thereof. Cleaning of the substrate structure with a supercritical fluid and/or dense fluid may be accomplished without the need for a wet clean. Cleaning or drying of the substrate structure with a supercritical fluid and/or dense fluid may be accomplished without the need for prior art vacuum bakes. A substrate having at least one feature with high aspect ratio apertures can be advantageously cleaning and/or dried with a supercritical fluid and/or a dense fluid. High aspect ratio apertures also act like a sponge taking up contaminants, non-reactive precursors, liquids very easily and are difficult to clean and dry out.

0062In one embodiment, supercritical fluid and/or dense fluid may be used to clean a substrate structure after dry stripping. For example, supercritical fluid and/or dense fluid may be used to remove or clean photoresist residue <b>312</b> from the porous low-k material layer <b>306</b> of substrate structure <b>302</b> shown in <figref idref="DRAWINGS">FIG. 3E</figref>. In one embodiment, the supercritical fluid and/or dense fluid further includes a chelating agent to help remove or clean conductive material residue <b>314</b>. In one aspect, cleaning of residue from a substrate structure with a supercritical fluid and/or dense fluid may be accomplished without the need for a wet clean. As a consequence, using a supercritical fluid and/or dense fluid to clean a substrate structure avoids the associated problems of using a wet clean.

0063In one embodiment, a substrate may be processed by applying a supercritical fluid thereto. In another embodiment, a substrate may be processed by applying a dense fluid thereto without the substance reaching a supercritical state. In still another embodiment, a substrate may be processed by applying a substance thereto in which the substance is phase modulated between a supercritical fluid state and a dense fluid state. A dense fluid may have a high solvating and diffusivity properties similar to a supercritical fluid. In one aspect, an apparatus adapted to apply a supercritical fluid to a substrate provides a supercritical fluid with greater solvating strength and diffusivity over a dense fluid. In another aspect, an apparatus adapted to only apply a dense fluid to a substrate is less complex than an apparatus adapted to apply a supercritical fluid due to the relatively higher temperatures and pressures used to achieve a supercritical fluid state.

0064In one preferred embodiment, the supercritical fluid and/or dense fluid used is carbon dioxide or xenon, more preferably carbon dioxide is used. In one aspect, carbon dioxide may be used to advantage as a supercritical fluid and/or dense fluid due to carbon dioxide's relatively low critical pressure (Pc=1050 psi) and relatively low critical temperature (Tc=31° C.) in comparison to other substances. In addition, carbon dioxide possesses less environmental risks in comparison to other substances which exhibit supercritical fluid properties. In one embodiment, dense carbon dioxide fluid comprises carbon dioxide at a temperature at least about 18° C. and at a pressure at least about 500 psi, and preferably comprises carbon dioxide at a temperature at least about 25° C. and at a pressure at least about 800 psi. In another embodiment, the supercritical fluid and/or dense fluid used is a fluid with a critical pressure below 4,500 psi, preferably below 2,000 psi, and/or a fluid with a critical temperature below 200° C., preferably below 120° C.

0065Supercritical fluids and/or dense fluids, such as carbon dioxide, may be used to advantage in processing a variety of materials used in semiconductor applications. Depending on the application, other optional components, such as co-solvents, surfactants, chelating agents, reactants, and combinations thereof, may be used in conjunction with the supercritical fluid and/or dense fluid. Examples of co-solvents include, but are not limited to, alcohols, halogenated solvents, esters, ethers, ketones, amines, amides, aromatics, aliphatic hydrocarbons, olefins, synthetic and natural hydrocarbons, organosilicones, alkyl pyrrolidones, paraffins, petroleum-based solvents, other suitable solvents, and mixtures thereof. The co-solvents may be miscible or immiscible with the supercritical fluid and/or dense fluid. Examples of chelating agents include, but are not limited to, chelating agent containing one or more amine or amide groups, such as ethylenediaminetetraacetic acid (EDTA), ethylenediaminedihyroxyphenylacetic acid (EDDHA), ethylenediamine, or methyl-formamide or other organic acids, such as iminodiacetic acid or oxalic acid. The term “surfactants” as used herein includes compounds that have one or more polar groups and one or more non-polar groups. It is believed that the surfactants help alter the interfacial characteristics of the supercritical fluid and/or dense fluid. Examples of surfactants include, but are not limited to, silicon-containing compounds, oxidizing agents, carbon-containing compounds, other reactants, and combinations thereof.

Platforms

0066The applications of processing substrates as disclosed herein may be carried out in one or more single chamber systems, in one or more mainframe systems having a plurality of chambers, in separate processing systems, in an integrated processing system, or in combinations thereof.

0067<figref idref="DRAWINGS">FIG. 5</figref> is a schematic top view of one embodiment of an integrated system <b>900</b> capable of performing the processes disclosed herein. As shown in the figure, the integrated system <b>500</b> is a LINK™ platform, available from Applied Materials, Inc., located in Santa Clara, Calif. The system <b>500</b> generally includes one or more substrate cassettes <b>502</b>, one or more transfer robots <b>504</b>, and one or more processing chambers <b>506</b>.

0068One example of the system <b>500</b> adapted to perform the method as described in <figref idref="DRAWINGS">FIG. 4</figref> comprises at least one of the processing chamber <b>506</b> adapted to provide a wet clean, such as a TEMPEST™ chamber, available from Applied Materials, Inc, located in Santa Clara, Calif. The system <b>500</b> further comprises at least one of the processing chambers <b>506</b> adapted to provide a supercritical fluid and/or a dense fluid, such as processing chamber <b>100</b> of <figref idref="DRAWINGS">FIG. 1</figref> or processing chamber <b>200</b> of <figref idref="DRAWINGS">FIG. 2</figref>. The system <b>500</b> further optionally further comprises at least one processing chamber <b>506</b> adapted to provide a dry strip, such as an AXIOM™ chamber, available from Applied Materials, Inc., located in Santa Clara, Calif.

0069One example of the system <b>500</b> adapted to perform the method as described in <figref idref="DRAWINGS">FIG. 5</figref> comprises at least one processing chamber <b>506</b> adapted to provide a dry strip, such as an AXIOM™ chamber, available from Applied Materials, Inc., located in Santa Clara, Calif. The system <b>500</b> further comprises at least one of the chambers <b>506</b> adapted to provide a supercritical fluid and/or a dense fluid, such as processing chamber <b>100</b> of <figref idref="DRAWINGS">FIG. 1</figref> or processing chamber <b>200</b> of <figref idref="DRAWINGS">FIG. 2</figref>.

0070One example of the system <b>500</b> adapted to perform methods of the invention may include at least one of the chambers <b>506</b> adapted to provide a supercritical fluid and/or a dense fluid, such as the processing chamber <b>100</b> of <figref idref="DRAWINGS">FIG. 1</figref> or the processing chamber <b>200</b> of <figref idref="DRAWINGS">FIG. 2</figref>. The system <b>500</b> further includes at least one processing chamber <b>506</b> adapted to provide a dry etch, such as an eMAX™ chamber or a DPS™ chamber, available from Applied Materials, Inc., located in Santa Clara, Calif. In addition, the system <b>500</b> may include at least one processing chamber <b>506</b> adapted to deposit a low-k material, such as a Black Diamond™ CVD chamber, available from Applied Materials, Inc., located in Santa Clara, Calif.

0071The processes as disclosed herein may be carried out in separate chambers or may be carried out in a multi-chamber processing system having a plurality of chambers. <figref idref="DRAWINGS">FIG. 6</figref> is a schematic top-view diagram of another example of a multi-chamber processing system <b>600</b> which may be adapted to perform processes as disclosed herein. The apparatus is an ENDURA™ system and is commercially available from Applied Materials, Inc., of Santa Clara, Calif. A similar multi-chamber processing system is disclosed in U.S. Pat. No. 5,186,718, entitled “Stage Vacuum Wafer Processing System and Method,” (Tepman et al.), issued on Feb. 16, 1993, where is hereby incorporated by reference to the extent not inconsistent with the present disclosure. The particular embodiment of the system <b>600</b> is provided to illustrate the invention and should not be used to limit the scope of the invention.

0072The system <b>600</b> generally includes load lock chambers <b>602</b>, <b>604</b> for the transfer of substrates into and out from the system <b>600</b>. Typically, since the system <b>600</b> is under vacuum, the load lock chambers <b>602</b>, <b>604</b> may “pump down” the substrates introduced into the system <b>600</b>. A first robot <b>610</b> may transfer the substrates between the load lock chambers <b>602</b>, <b>604</b>, processing chambers <b>612</b>, <b>614</b>, transfer chambers <b>622</b>, <b>624</b>, and other chambers <b>616</b>, <b>618</b>. A second robot <b>630</b> may transfer the substrates between processing chambers <b>632</b>, <b>634</b>, <b>636</b>, <b>638</b> and the transfer chambers <b>622</b>, <b>624</b>. Processing chambers <b>612</b>, <b>614</b>, <b>632</b>, <b>634</b>, <b>636</b>, <b>638</b> may be removed from the system <b>600</b> if not necessary for the particular process to be performed by the system <b>600</b>.

0073In one embodiment, the system <b>600</b> is configured so that at least one of the processing chambers is adapted to deposit a copper seed layer <b>410</b>. For example, the processing chamber <b>634</b> for depositing a copper seed layer <b>410</b> may be the processing chamber <b>100</b> or the processing chamber <b>200</b>. In addition, the processing chambers of the system <b>600</b> may include an annealing chamber, a pre-heating chamber, a cleaning chamber, a load lock chamber, a physical vapor deposition chamber, a chemical vapor deposition chamber, or an atomic layer deposition chamber. The system <b>600</b> may be further configured so that processing chamber <b>632</b> is adapted to deposit a barrier layer <b>204</b> in which the copper seed layer <b>410</b> is deposited over the barrier layer <b>204</b>. For example, the processing chamber <b>632</b> for depositing the barrier layer <b>204</b> may be an atomic layer deposition chamber, a chemical vapor deposition chamber, or a physical vapor deposition chamber. In one aspect, deposition of a barrier layer <b>204</b> and a copper seed layer <b>410</b> may be performed in a multi-chamber processing system under vacuum to prevent air and other impurities from being incorporated into the layers and to maintain the seed structure over the barrier layer <b>204</b>. Other embodiments of the system <b>600</b> are within the scope of the present invention. For example, the position of a particular processing chamber on the system may be altered. In another example, a single processing chamber may be adapted to deposit two different layers. The above particular embodiments of the systems <b>500</b>, <b>600</b> to perform the process as disclosed herein is provided to illustrate the invention and should not be used to limit the scope of the invention unless otherwise set forth in the claims.

0074While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.