Patent Application
20050126588
The invention relates to compositions and methods for chemical-mechanical polishing/planarization and/or post-CMP cleaning of metal-containing substrates with a composition containing an oxidizer and an organic or inorganic acid, and more particularly to compositions and methods for chemical-mechanical polishing/planarization and/or post-CMP cleaning of copper-containing substrates used in integrated circuit manufacture.
Chemical-mechanical polishing or planarization (CMP) processes are well-known. See, for example, Chemical Mechanical Polishing in Silicon Processing, Semiconductors and Semimetals, Vol. 62, Edited by Li, S. et al., which is expressly incorporated herein by reference. Also directly incorporated by reference for all purposes are the following commonly assigned patents:
CMP processes are commonly used to polish or “planarize” the surfaces of wafers at various stages of fabrication to improve wafer yield, performance and reliability. In CMP, typically the wafer is held in place on a mount using negative pressure, such as vacuum, or hydrostatic or pneumatic pressure. The mount is typically situated over a polishing pad. CMP generally involves applying a polishing composition or slurry to the polishing pad, establishing pressure-contact between the composition- or slurry-coated wafer surface and the polishing pad while providing relative motion, typically rotational or orbital motion, between the wafer surface and the polishing pad.
The polishing composition typically contains an abrasive material, such as silica, ceria, and/or alumina particles, in an acidic, neutral, or basic solution. Merely by way of example, a polishing composition useful in the CMP of tungsten material on a substrate may contain abrasive alumina, also called aluminum oxide, an oxidizing agent such as hydrogen peroxide, and either potassium hydroxide or ammonium hydroxide. A CMP process employing such a polishing composition may provide a predictable rate of polishing, while largely preserving desirable features on the wafer surface.
For such a semiconductor wafer, a typical CMP process involves polishing the metal in a controlled manner to preferentially etch certain conductors, insulators or both over the the oxide beneath the metal, such that the metal is substantially coplanar with the oxide and remains in the grooves or stud vias of the oxide. After CMP, the substantially coplanar surface is ready for further processing. CMP is currently the primary method used to polish or “planarize” wafers in back end of the line (BEOL) processes.
Semiconductor fabrication processes such as photolithography have evolved significantly, such that advanced devices having very fine oxide, metal, and other surface features, with sub-0.25 micron geometries (such as 0.18 micron or less), are now being made. Process tolerances are necessarily tighter for these advanced devices, calling for improvements in CMP technology to obtain desired material removal rates while minimizing wafer defects or damage. A variety of approaches have been taken in an effort to improve CMP processes to improve planarity.
On the other hand, economic forces are requiring the use of faster processing. One approach has involved increasing the downward pressure on the wafer carrier in order to increase material removal rates. This approach is generally disfavored as the requisite downward pressure is considered too high and too likely to cause wafer damage, such as scratching, delamination, or destruction of material layers on the wafer. When the wafer is fragile, as is generally the case with substrates layered with films such as porous films having a low dielectric constant, these damage issues are particularly acute and detrimental in terms of wafer yield and performance. Generally, faster chemical-mechanical polishing results in more defects.
Additional approaches have involved using various protected combinations of oxidizers, chelators, corrosion inhibitors, solvents, and other chemicals in the slurry, various abrasives including for example a zirconium abrasive or mixed abrasives, and/or using point-of-use mixing techniques. These approaches are generally undesirable, as they typically complicate CMP in terms of tooling and process control for example, consume more process time, and/or increase costs.
Chelators act on the metal surface of the substrate to turn metal oxides water soluble. Examples of chelators include a wide range of organic acids, such as salicylic acid, see e.g. U.S. patent application Ser. Nos. 09/795,421;. 09/859,147; 10/393,074 & 10/246,280. Other approaches have included the use of phosphoric acid as well as organic acids. U.S. patent application Ser. No. 10/396,410. Chelators may be used in conjunction with oxidizers. When an oxidizer and chelator are used in combination, excessive corrosion of the substrate may result. As a solution to this problem, corrosion inhibitors may be added to the composition. For the typical CMP substrate—copper—examples of corrosion inhibitors include imidazole or benzothiazole. Addition of such corrosion inhibitors can be cumbersome often requiring a specialized method. See e.g. JP-A-11-21546. Furthermore, the chemistry of CMP compositions may limit the group of suitable corrosion inhibitors.
U.S. Pat. No. 5,417,877 describes organic stripping compositions for use in stripping polymeric material, where the composition comprises polar organic solvents, basic amines, and inhibitors, wherein the broad class of inhibitors described includes salicylic acid compounds.
U.S. Patent Publication No. 2003/0130147 describes stripping and residue removing compositions having 1) glycol ethers, alcohols having a cyclic alkoxy group, alcohols having a heterocyclic oxy group containing nitrogen or sulfur as the hetero atom, or alcohols having a cyclic ether structure containing at least oxygen as the hetero atom; and 2) anticorrosives selected from aromatic hydroxyl compounds, acetylenic alcohol, carboxyl-group-containing organic compounds such as quinaldinic acid, triazole-based compounds, and/or purine-based compounds, and may optionally contain any of water, an organic acid of which salycilic acid is an example, and amines.
U.S. Patent Publication No. 2002/0019202 describes a two-step CMP method for semi-conductors with composition that can include complexing agents such as salicylic acid, 3-hydroxy-salicylic acid, or 3,5-hydroxy-salicylic acid, inter alia, but preferably citric acid, and corrosion inhibitors such as substituted or unsubstituted benzotriazoles, preferably benzotriazole.
U.S. Patent Publication Nos. 2001/0024933 and 2003/0181046 describe a CMP composition and method that contains an oxidizing agent, an organic polymer removal rate suppressant, and optionally a complexing agent, which can include salicylic acid, 3-hydroxy-salicylic acid, or 3,5-hydroxy-salicylic acid, ethylenediamine, and ethyl acetoacetate, inter alia.
U.S. Patent Publication Nos. 2002/0016073 and 2003/0186497 describe compositions and methods for polishing semiconductors containing an oxidizer, phosphoric acid, organic acid, a corrosion inhibition, and water. While salicylic acid is listed as one of the organic acids in these publications, it is not a preferred acid, nor is it mentioned as a corrosion inhibitor.
U.S. Patent Publication No. 2003/0041526 describes a polishing composition having an index of degree of sedimentation from 80 to 100 and which can contain an abrasive, water, and optionally a 2-20 carbon atom hydroxy-functional or mercapto-functional carboxylic acid. While salicylic acid is listed as one of the functional carboxylic acids in this publication, it is not a preferred acid.
U.S. Patent Publication No. 2002/0017630 discloses a liquid abrasive composition containing (1) an oxidizing agent for a metal, (2) a dissolving agent for an oxidized metal, (3) a first protecting film-forming agent such as an amino acid or an azole which adsorbs physically on the surface of the metal and/or forms a chemical bond, to thereby form a protecting film, (4) a second protecting film-forming agent such as polyacrylic acid, polyamido acid or a salt thereof which assists the first protecting film-forming agent informing a protecting film and (5) water. While salicylic acid is listed as one of the dissolving agents in this publication, it is not disclosed as being a preferred organic acid for this purpose.
U.S. Patent Publication No. 2001/0014534 stripper composition containing: an anticorrosive agent containing (a) urea or a urea derivative and (b) a hydroxy aromatic compound; optionally (c) a hydroxylamine or an alkanolamine; and optionally (d) water. While salicylic acid is listed as one of the hydroxy aromatic compounds in this publication, it is not a preferred element of the anticorrosive agent.
U.S. Patent Publication No. 2003/0181345 describes a CMP solution for removing tantalum barrier materials that contains up to 25 wt % of an oxidizer, up to 15 wt % of an inhibitor for a nonferrous metal, up to 20 wt % of a complexing agent for the nonferrous metal, 0.01 to 12 wt % of a tantalum removal agent, up to 5 wt % of an abrasive, up to 15 wt of polymeric or polymer-coated particles, and the balance water. While salicylic acid, 3-hydroxysalicylic acid, and 3,5-dihydroxysalicylic acid are listed as examples of complexing agents in this publication, none are preferred complexing agents, nor are any mentioned as non-ferrous metal corrosion inhibitors.
U.S. Patent Publication No. 2002/0169088 describes a cleaning composition comprises a carboxylic acid, an amine-containing compound, a phosphonic acid, and water. While salicylic acid (a monocarboxylic acid) is listed as one of the carboxylic acids in this publication, the publication teaches that preferred acids contain at least two carboxylic acid groups, with three carboxylic acid groups being even more preferred.
U.S. Patent Publication No. 2002/0034925 discloses a semiconductor polishing process using a slurry composition comprising abrasives dispersed in an a medium. According to the publication, the abrasive can be made of organic matter, which may include, inter alia, acetylsalicylic acid and salts of salicylic acids.
U.S. Patent Publication No. 2003/0171239 discloses methods and compositions for treating a surface of a substrate by foam technology using a liquid composition containing a gas; a surfactant; and at least one component selected from the group consisting of a fluoride, a hydroxylamine, an amine, and periodic acid.
U.S. Patent Publication No. 2003/0137052 discloses a method for semi-conductor manufacturing that includes: a CMP step using a composition containing quinaldinic acid, lactic acid, colloidal silica, hydrogen peroxide, and optionally benzotriazole, followed by an oxygen-rich water polish; a post-CMP cleaning step using at least one of an organic acid (that can include, inter alia, salicylic acid), an inorganic acid, and an alkali, optionally a surface-active agent, and optionally a separate chelating agent such as EDTA; and a rinsing step using an oxygen-rich aqueous solution.
U.S. Patent Publication No. 2003/0130147 discloses a stripping composition containing a hydroxy-functional ether compound, an anticorrosive agent, and optionally a weak organic or inorganic acid. While salicylic acid is listed as one of the weak organic acids in this publication, it is not a preferred optional acid component.
Another approach has involved increasing the amount of oxidizing agent used in the CMP slurry in an effort to increase chemical removal of targeted material. This approach is largely disfavored as the use of increased amounts of oxidizing agents increase material costs and also detrimentally add to the handling issues and environmental issues associated with many oxidizing agents and also increase costs.
It is generally known that oxidizers admixed in a solution can provide synergistic etching rates. While ferric salts, cerium salts, peroxides, persulfates, or hydroxylamines form the oxidizing capacity of most commercially available CMP slurries, those of ordinary skill in the art have long known that these oxidizers can be admixed with others in this group and also with other oxidizers, and the resulting composition can show synergistic results.
Certain metals, such as those with a tendency to plate on or be absorbed on to at least one part of the substrate, are more damaging than other metals. The industry has developed methods to remove a portion of the metallic contamination, for example by: physical desorption by solvents; changing the surface charge with either acids or bases so that Si——OH or M——OH group can be protonated (made positive) in acid or made negative with bases by removing the proton; ion competition, for example removing adsorbed metal ions by adding acid (i.e. ion exchange); subsequent oxidation of metals to change the chemical bonds between the impurities and substrate surface; and subsequent etching the surface, wherein the impurity and a certain thickness of the substrate surface is removed, as described in U.S. Pat. No. 6,313,039, the contents of which has been incorporated herein by reference. This patent taught the synergistic use of combinations of oxidizers, partticularly non-transition-metal-containing oxidizers, including a ammonium persulfate/peroxymonosulfate system; a hydroxylamine nitrate/hydroxylamine system; an ammonium persulfate/periodic acid system (for example at 0.5% to 2% periodic acid concentrations; a hydrogen peroxide/hydroxylamine system; an ammonium persulfate/potassium periodate system; and an ammonium persulfate/potassium iodate system. There have been various “post-polishing cleaners” developed to remove metallic contamination, but removal of all undesired metal ions is substantially beyond the range of cleaners, and as the size of the structures continues to decrease, even a very small number of metallic atoms deposited on a surface will result in undesired shorts or current leakage.
Therefore, despite the known advantages of having multiple oxidizers, for example a metal-containing oxidizer admixed with either another metal-containing oxidizer or with a non-metal-containing oxidizer, there has been a tendency in the industry to reduce the amount of metal ions in CMP slurries. Additionally, metal ion-containing fluids are often environmentally undesirable and expensive treatment may be needed prior to waste disposal of used product.
Chemical-mechanical planarization (CMP) and post-CMP cleaning have become key steps in the fabrication of high-speed integrated circuits. The oxidant in CMP slurries plays a critical role in controlling the removal rate and planarity of metal films that are polished. Recently, hydroxylamine-(NH2OH—) based oxidants have been introduced for chemical mechanical polishing of copper. See, e.g., International Publication No. WO 98/04646 and M. L. Peterson et al., Semiconductor Fabtech, 11th ed. (2000), the entire contents of which are hereby incorporated by reference for all purposes. The etch rate and CMP removal rate of copper in. hydroxylamine based solutions is a strong function of pH and exhibits a maximum in the vicinity of pH 6. See, e.g., W. Huang et al., Chemical Mechanical Planarization in IC DEVICE MANUFACTURING III, PV 99-37, p. 101, The Electrochemical Society Proceedings Series, Pennington, N.J. (1999). The removal rates at pH 6 can be modulated through the use of a corrosion inhibitor such as benzotriazole (BTA). While BTA has been known to be a very good corrosion inhibitor for copper for many decades, due to certain environmental limitations imposed by this compound, the CMP industry has been looking for alternatives to BTA.
EKC Technology/Dupont Electronic Technologies, a large commercial manufacturer of CMP slurries, sells several high-purity, non-metal-based CMP slurries for tungsten, for example the MicroPlanar® CMP3550™/ MicroPlanar® CMP3510™ slurry, as well as the traditional but effective ferric nitrate as the oxidizer with a post-CMP cleaner to remove metal contaminants.
Further developments in the field of CMP technology are desired. Alternative corrosion inhibitor additives for use in metal free oxidizer-based, for example hydrogen peroxide-based, CMP solutions/slurries are addressed herein.
The invention provides a method for chemically polishing mechanically polishing a metal-containing substrate comprising contacting a metal-containing substrate with a composition comprising: an oxidizing agent; between about 0.0001 M to about 1 M of a salicylic acid compound, wherein the salicylic acid compound is present in an amount sufficient to substantially inhibit corrosion and water, at a temperature and for a time sufficient to chemically mechanically polish the metal-containing substrate.
The invention further provides a method of cleaning a metal-containing substrate that had previously undergone a chemical mechanical polishing process comprising the steps of contacting the chemically mechanically polished metal-containing substrate with a composition comprising: an oxidizer; a salicylic acid compound and water, at a temperature and for a time sufficient to clean the metal-containing substrate.
The invention further provides a method of a post-etch residue removal for a metal-containing substrate comprising the steps of contacting the chemically mechanically polished metal-containing substrate with a composition comprising of: an oxidizer; a salicylic acid compound; and water at a at a temperature and for a time sufficient to remove post-etch residue from the metal-containing substrate.
Benzotriazole (BTA) is a well-known corrosion inhibitor for copper in various applications in a wide-range of environments. The chemistry of interaction of benzotriazole (BTA) with copper has been studied extensively. See, e.g., G. W. Poling, Corros. Sci., (1970), 10, p.359, and V. Brusic et al., Electrochem. Soc., (1991), 138, p.2253. It is generally accepted that BTA (as well as BTA-ion) chemisorbs on the copper surface and forms an insoluble cuprous surface complex. Under certain conditions the formation of a thick, multilayered coating has been confirmed. See, e.g., V. Brusic et al., Electrochem. Soc., (1991), 138, p.2253.
One aspect of the present invention includes a composition, e.g., used in a method for chemical mechanical polishing of a metal-containing substrate, particularly of copper-containing substrates, containing: between about 0.01% and about 30% by weight of an oxidizing agent based on weight of fluid; between about 0.00001M to about 0.5M, preferably from about 0.00005M to about 0.05M, for example from about 0.00005M to about 0.001M, from about 0.0001M to about 0.01M, from about 0.0001M to about 0.001M, from about 0.001M to about 0.01M, or from about 0.01M to about 0.5M of salicylic acid or a salicylic acid derivative; water; and optionally an abrasive.
Generally, any quantity of salicylic acid and/or its derivative(s), particularly salicylic acid, can act as a chelator while there can typically be a certain minimum quantity before the salicylic acid and/or its derivative(s), for example salicylic acid, can become effective as a corrosion inhibitor.
Generally, a quantity greater than about 0.005M, preferably greater than about 0.01M, of salicylic acid will function as a corrosion inhibitor. When used in a CMP step on a copper-containing substrate, for example, the amount of salicylic acid and/or its derivative(s) present can advantageously be at least sufficient to chelate at least about 50% of the copper chemically and/or mechanically polished from the substrate during the CMP process, for example such that not more than about 300 ppm of unchelated copper ions are present in the CMP solution/slurry, more preferably at least about 75% of the available copper ions in solution and/or such that not more than about 100 ppm, or not more than about 50 ppm of unchelated copper ions are present in the CMP solution/slurry. When used for example in shallow trench isolation (STI) processes, it is advantageous to have sufficient salicylic acid and/or its derivative compounds available to act as a corrosion inhibitor.
When used in a post-CMP cleaning step of a copper-containing substrate, the fluid advantageously contains an oxidizer, and includes an amount of salicylic acid and/or its derivative(s) also advantageously sufficient to at least partially inhibit corrosion of at least a portion of the copper-containing substrate (or of a copper-containing layer of a multi-layer substrate) during the cleaning process, preferably to substantially inhibit corrosion of the copper-containing portion(s) of the substrate. As used herein, the term “substantially” should be understood to refer to a level of at least about 30%, preferably a level of at least about 70%, more preferably a level of at least about 90%, for example a level of at least about 95% compared to the corrosion observed using a solution without the salicylic acid compound. In a preferred embodiment, the term “substantially” can mean completely. Generally, any quantity of salicylic acid and/or its derivative(s), particularly salicylic acid, can act as a chelator while there can typically be a certain minimum quantity before the salicylic acid and/or its derivative(s), particularly salicylic acid, can become effective as a corrosion inhibitor. The amount of salicylic acid and/or its derivative(s) can be from about 0.00001M to about 1 M, for example from about 0.05M to about 0.2M, alternatively from about 0.00005M to about 0.001M, from about 0.001M to about 0.01M, alternatively from about 0.01M to about 0.1M, alternatively from about 0.1M to about 0.5M. A quantity greater than about 0.005M, preferably greater than about 0.01M, of salicylic acid will be most useful as a corrosion inhibitor.
The composition according to the invention can be used on a metal-containing substrate, preferably a copper-containing substrate and/or a tantalum-containing substrate (e.g., copper, copper alloys such as Cu—Al, tantalum, tantalum nitrides, tantalum oxynitrides, tantalum oxides, tantalum alloys, and the like, and combinations thereof). The composition can contain an oxidizing agent, preferably an organic or inorganic peroxide such as hydrogen peroxide, a corrosion inhibitor substitute for benzotriazole, preferably a salicylic acid and/or a derivative thereof such as salicylic acid, water, and optionally an abrasive. When used as a CMP slurry, it is preferred that the composition contain an abrasive. However, it is envisioned that the CMP composition may be used in conjunction with an abrasive polishing pad (e.g., a polishing pad having abrasive particles attached thereto or contained therein), in which case the abrasive in the slurry may be unnecessary and therefore optional. When used in a post-CMP cleaner, generally the abrasive is not desired.
The present invention can be used in conjunction with any suitable substrate. In particular, the present invention can be used in conjunction with memory or rigid disks, metals (e.g., noble metals), ILD layers, integrated circuits, semiconductor devices, semiconductor wafers, micro-electro-mechanical systems, ferroelectrics, magnetic heads, polymeric films, and low and high dielectric constant films, and technical or optical glass. Suitable substrates comprise, for example, a metal, metal oxide, metal composite, or mixtures thereof. The substrate can comprise, consist essentially of, or consist of any suitable metal. Suitable metals include, for example, copper, aluminum, titanium, tungsten, tantalum, gold, platinum, iridium, ruthenium, and combinations (e.g., alloys or mixtures) thereof. The substrate also can comprise, consist essentially of, or consist of any suitable metal oxide. Suitable metal oxides include, for example, alumina, silica, titania, ceria, zirconia, germania, magnesia, and coformed products thereof, and mixtures thereof. In addition, the substrate can comprise, consist essentially of, or consist of any suitable metal composite and/or metal alloy. Suitable metal composites and metal alloys include, for example, metal nitrides (e.g., tantalum nitride, titanium nitride, and tungsten nitride), metal carbides (e.g., silicon carbide and tungsten carbide), nickel-phosphorus, alumino-borosilicate, borosilicate glass, phosphosilicate glass (PSG), borophosphosilicate glass (BPSG)), silicon/germanium alloys, and silicon/germanium/carbon alloys. The substrate also can comprise, consist essentially of, or consist of any suitable semiconductor base material. Suitable semiconductor base materials include single-crystal silicon, poly-crystalline silicon, amorphous silicon, silicon-on-insulator, and gallium arsenide. Glass substrates can also be used in conjunction with the present invention including technical glass, optical glass, and ceramics, of various types known in the art.
The formulations are particularly useful on substrates comprising, consisting essentially of, or consisting of copper, a copper alloy, and/or a copper compound, and the substrate may also contain one or more barrier materials as are known in the art, such as Ta, TaN, Ti, TiN, or combinations thereof
The present invention can be used to polish any part of a substrate (e.g., a semiconductor device) at any stage in the production of the substrate. For example, the present invention can be used to polish a semiconductor device in conjunction with shallow trench isolation (STI) processing, as set forth, for example, in U.S. Pat. Nos. 5,498,565; 5,721,173; 5,938,505; and 6,019,806, or in conjunction with the formation of an interlayer dielectric.
The present invention, incorporated into a chemical mechanical polishing composition, a post-etch residue remover, or a post-CMP cleaner, can be used in conjunction with any suitable component (or ingredient) known in the art for each category, for example, abrasives, oxidizing agents, catalysts, film-forming agents, complexing agents, Theological control agents, surfactants (i.e., surface-active agents), polymeric stabilizers, pH-adjusters, and other appropriate ingredients.
The abrasive, when present in the compositions according to the embodiments used for chemical mechanical polishing, can be any suitable abrasive known in the CMP art. For example, suitable abrasives can include, but are not limited to, silica, ceria, alumina, zirconia, titania, metal coated particles thereof (e.g., iron-coated silica), magnesia, co-formed products thereof, mixtures thereof, and chemical admixtures thereof. The term “chemical admixture” refers to particles including atomically mixed or coated metal oxide abrasive mixtures. Suitable abrasives also include heat-treated abrasives and chemically-treated abrasives (e.g., abrasives with chemically-linked organic functional groups).
The amount of abrasive, when present in the compositions according to the invention, can advantageously be from about 0.01% to about 30% by weight, preferably from about 0.01% to about 10%, for example from about 0.01% to about 5% or from about 0.1% to about 10%. In some embodiments according to the invention, the composition can be substantially free of abrasives.
The abrasive can be produced by any suitable technique known to one of ordinary skill in the art. The abrasive can be derived, for example, from any process known in the art, including flame processes, sol-gel processes, hydrothermal processes, plasma processes, aerogel processes, fuming processes, precipitation processes, mining, and combinations of processes thereof. The abrasive can be a condensation-polymerized metal oxide, e.g., condensation-polymerized silica. A suitable abrasive also can comprise, consist essentially of, or consist of high-temperature crystalline phases of alumina consisting of gamma, theta, delta, and alpha alumina, and/or low-temperature phases of alumina consisting of all non-high temperature crystalline alumina phases.
The abrasive can be combined with any suitable carrier (e.g., an aqueous carrier) to form a “dispersion” (e.g., a “slurry”). Suitable dispersions can have any suitable concentration of abrasive.
The abrasive can have any suitable abrasive particle characteristics depending on the desired polishing effects. In particular, the abrasive can have any suitable surface area. A suitable abrasive surface area, for example, is a surface area ranging from about 5 m2/g to about 430 m2/g, as calculated from the method of S. Brunauer, P. H. Emrnet, and I. Teller, J. Am. Chemical Society, 60, 309 (1938). Alternatively, it is also suitable for the abrasive to have essentially a bimodal particle size distribution.
Any suitable oxidizing agent can be used in conjunction with the present invention. Suitable oxidizing agents include, for example, oxidized halides (e.g., chlorates, bromates, iodates, perchlorates, perbromates, periodates, fluoride-containing compounds, and mixtures thereof, and the like). Suitable oxidizing agents also include, for example, perboric acid, periodic acid, periodates, perborates, percarbonates, nitrates (e.g., iron (III) nitrate, and hydroxylamine nitrate), persulfates (e.g., ammonium persulfate), organic peroxides such as benzoyl peroxide, inorganic peroxides such as hydrogen peroxide, peroxyacids (e.g., peracetic acid, perbenzoic acid, m-chloroperbenzoic acid, salts thereof, mixtures thereof, and the like), permanganates, chromates, cerium compounds, ferricyanides (e.g., potassium ferricyanide), mixtures thereof, and the like. Suitable oxidizers also include hydroxylamine, hydroxylamine derivatives, and/or salts thereof Examples of suitable hydroxylamine or hydroxylamine derivative include hydroxylamine, N-methyl-hydroxylamine, N,N-dimethyl-hydroxylamine, N-ethyl-hydroxylamine, N,N-diethyl-hydroxylamine, hydroxylamine nitrate, hydroxylamine sulfate, hydroxylamine phosphate. Suitable oxidizers can often be mixtures of two or more of the above-listed oxidizers, in a range of from about 100:1 to about 1:100. The amount of suitable oxidizing agent or agents can be between about 0.01% to about 30%, e.g., between 0.01% and about 2%, alternatively between about 2% and about 5%, alternatively between about 5% and about 10%, alternatively between about 10% and about 17.5%, alternatively between about 17.5% and about 25%, alternatively between about 25% and about 30%.
Any suitable film-forming agent (i.e., corrosion-inhibitor) can be used in conjunction with the present invention, supplementing the film-forming capacity of the salicylic acid and/or its derivative(s). Suitable film-forming agents include, for example, heterocyclic organic compounds (e.g., organic compounds with one or more active functional groups, such as heterocyclic rings, particularly nitrogen-containing heterocyclic rings). Suitable film-forming agents also include, for example, benzotriazole, triazole, benzimidazole, and mixtures thereof. In one embodiment, the film-forming agent can be present in an amount from about 0.05% to about 10% (exclusive of the salicylic acid and/or its derivative compounds according to this invention) by weight based on the weight of the fluid.
Any suitable complexing agent (i.e., chelating agent or selectivity enhancer) can be used in conjunction with the present invention, supplementing the chelating capacity of the salicylic acid and/or its derivative(s). Suitable complexing agents include, for example, carbonyl compounds (e.g., acetylacetonates and the like), simple carboxylates (e.g., acetates, aryl carboxylates, and the like), carboxylates containing one or more hydroxyl groups (e.g., glycolates, lactates, gluconates, gallic acid and salts thereof, and the like), di-, tri-, and poly-carboxylates (e.g., oxalates, phthalates, citrates, succinates, tartrates, maleates, glycolates, edetates such as disodium EDTA, mixtures thereof, and the like), carboxylates containing one or more sulfonic and/or phosphonic groups, and carboxylates, di-, tri-, or poly-alcohols (e.g., ethylene glycol, pyrocatechol, pyrogallol, tannic acid, and the like), phosphate-containing compounds (e.g., phosphonium salts, phosphonic acids, and the like), amine-containing compounds (e.g., amino acids, amino alcohols, di-, tri-, and poly-amines, and the like), or mixtures thereof. In one embodiment, a complexing agent can be present in an amount from about 0.005% to about 5% by weight (exclusive of the salicylic acid and/or its derivative compounds according to this invention) based on the weight of the fluid.
Any suitable surfactant and/or rheological control agent can be used in conjunction with the present invention, including viscosity enhancing agents and coagulants. Suitable rheological control agents include, for example, polymeric rheological control agents. Moreover, suitable rheological control agents include, for example, urethane polymers (e.g., urethane polymers with a molecular weight greater than about 100,000 Daltons), acrylates comprising one or more acrylic subunits (e.g., vinyl acrylates and styrene acrylates), polymers, copolymers, and oligomers thereof, and salts thereof. Suitable surfactants include, for example, cationic surfactants, anionic surfactants, anionic polyelectrolytes, nonionic surfactants, amphoteric surfactants, fluorinated surfactants, mixtures thereof, and the like. In one embodiment, the surfactant and/or rheological control agent can be present in an amount from about 0.005% to about 4% by weight based on the weight of the fluid.
The composition used in conjunction with the present invention can contain any suitable polymeric stabilizer or other surface active dispersing agent, for example, phosphoric acid, organic acids, tin oxides, organic phosphonates, and the like, and mixtures thereof. In one embodiment, the polymeric stabilizer can be present in an amount from about 0.01% to about 3% by weight based on the weight of the fluid.
Any of the components used in conjunction with the present invention can be provided in the form of a mixture or solution in an appropriate carrier liquid or solvent (e.g., water or an appropriate organic solvent).
Furthermore, as mentioned, the compounds, alone or in any combination, can be used as a component of a polishing, residue removing or cleaning composition. Two or more components then are individually stored and subsequently mixed to form a polishing or cleaning composition at, or immediately before reaching, the point-of-use.
A component can have any pH appropriate in view of the storage and contemplated end-use, as will be appreciated by those of skill in the art. Moreover, the pH of a component used in conjunction with the present invention can be adjusted in any suitable manner, e.g., by adding a pH adjuster, regulator, or buffer. Suitable pH adjusters, regulators, or buffers include acids, such as, for example, hydrochloric acid, acids such as mineral acids (e.g., nitric acid, sulfuric acid, phosphoric acid, and the like), and organic acids (e.g., acetic acid, citric acid, malonic acid, succinic acid, tartaric acid, oxalic acid, glycolic acid, and the like). Suitable pH adjusters, regulators, or buffers also include bases, such as, for example, inorganic hydroxide bases (e.g., sodium hydroxide, potassium hydroxide, ammonium hydroxide, and the like) and carbonate bases (e.g., sodium carbonate and the like). In one preferred embodiment, the composition contains an organic acid such as acetic acid.
As described above, various embodiments of the invention can contain other additives, including, but not limited to, polar organic solvents, non-polar organic solvents, surfactants, chelating agents and/or corrosion inhibitors other than salicylic acids and their derivatives, non-hydroxyl-containing amines, other hydroxyl-containing amines such as alkanolamines, organic and/or inorganic acids and/or bases (e.g., to control pH), oxidizing agents other than hydroxylamine or its derivatives, ammonium salts, mono-, di-, tri-, and/or tetra- alkylammonium salts, or the like, or a combination thereof. In a preferred embodiment, the above described compositions can also be substantially free from one or more of the following: polar organic solvents; non-polar organic solvents; surfactants; chelating agents and/or corrosion inhibitors other than salicylic acids and their derivatives; non-hydroxyl-containing amines; other hydroxyl-containing amines such as alkanolamines; organic and/or inorganic acids and/or bases (e.g., to control pH); oxidizing agents other than organic or inorganic peroxides such as hydrogen peroxide; ammonium salts; and mono-, di-, tri-, and/or tetra- alkylammonium salts.
The polishing and cleaning components described herein can be combined in any manner and proportion to provide one or more compositions suitable for polishing or cleaning a substrate (e.g., a semiconductor substrate).
Another aspect of the present invention includes a composition, e.g., used for chemical mechanical polishing or post-CMP cleaning, particularly of copper-containing substrates, containing an organic or inorganic peroxide such as hydrogen peroxide, salicylic acid and/or its derivative(s), particularly salicylic acid, water, an organic acid such as acetic acid, and optionally an abrasive such as silica. When used in a CMP step on a copper-containing substrate, the amount of salicylic acid and/or its derivative(s) present is advantageously sufficient to chelate a portion of the copper chemically and/or mechanically polished from the substrate during the CMP process, preferably at least about 50% of the available copper ions in solution and/or such that not more than about 100 ppm of unchelated copper ions are present in the CMP solution/slurry, more preferably at least about 75% of the available copper ions in solution and/or such that not more than about 50 ppm of unchelated copper ions are present in the CMP solution/slurry. When used in a post-CMP cleaning step of a copper-containing substrate, the amount of salicylic acid and/or its derivative(s), particularly salicylic acid, present is advantageously sufficient to inhibit corrosion of at least a portion of the copper-containing substrate (or of a copper-containing layer of a multi-layer substrate) during the cleaning process, preferably to substantially inhibit corrosion of the copper-containing portion(s) of the substrate. As used herein, the term “substantially inhibit” should be understood to refer to inhibiting static corrosion to a level of at least about 30%, preferably a level of at least about 70%, more preferably a level of at least about 90%, for example a level of at least about 95% less than is observed with a similar composition not containing the salicylic acid. In a preferred embodiment, the term “substantially” can mean completely.
Advantageously, the composition according to the invention can be an aqueous solution containing salicylic acid and/or its derivative(s), and an organic or inorganic peroxide such as hydrogen peroxide, or an aqueous slurry containing salicylic acid and/or its derivative(s), an organic or inorganic peroxide such as hydrogen peroxide, and an abrasive. In one embodiment, the composition consists essentially of water, acetic acid, salicylic acid, and hydrogen peroxide. In another embodiment, the composition consists essentially of water, acetic acid, salicylic acid, hydrogen peroxide, and an abrasive such as silica.
The amount of organic and/or inorganic peroxide in the compositions according to the invention can advantageously be from about 0.01M to about 3M, preferably from about 0.01M to about 1M, for example from about 0.05M to about 0.5M. As used herein, the designation “M” refers to molarity, which is typically expressed in moles per liter of composition. In an alternate embodiment, the amount of organic and/or inorganic peroxide in the compositions according to the invention can advantageously be from about 0.01% to about 25% by weight, preferably from about 0.03% to about 15% by weight, for example from about 0.03% to about 0.5% by weight, from about 0.1% to about 1% by weight, from about 1% to about 15% by weight, from about 0.1% to about 5% by weight, from about 0.5% to about 5% by weight, from about 0.03% to about 1% by weight, or from about 10% to about 15% by weight.
Salicylic acid compound derivatives are compounds having the general formula:
where R1 and R2 can independently be hydrogen; an organic salt/counterion such as ammonium, a mono-, di-, tri-, or tetra- C1-C8 alkyl ammonium, or the like; an inorganic salt/counterion such as sodium, potassium, lithium, a phosphonium, or the like; a C1-C20 linear or branched, saturated or unsaturated, optionally singly or multiply substituted alkyl moiety; a C5-C20 optionally singly or multiply substituted aryl or heteroaryl moiety; or a combination thereof, and where R3 is a hydrogen, a C1-C20 linear or branched, saturated or unsaturated, optionally singly or multiply substituted alkyl moiety, a C5-C20 optionally singly or multiply substituted aryl or heteroaryl moiety, or a combination thereof. Optionally substituted moieties can include, but are not limited to hydroxyls, nitro groups, sulfates, phosphates, amines, amides, carboxylic acids, carboxylate salts, carboxylate esters, halides, alkyl or aryl ethers, C1-C6 linear or branched, saturated or unsaturated alkyl groups, C5-C12 aryl groups, or the like, or a combination or reaction product thereof. In one preferred embodiment, R1, R2, and R3 are all hydrogen (i.e., which results in salicylic acid). In another preferred embodiment, R2 and R3 are both hydrogen and R1 is a an inorganic salt/counterion.
Salicylic acid compounds according to the invention can additionally or alternately include complexes of salicylic acid (i.e., R1, R2, and R3 are all hydrogen, as above) with other molecules, e.g., triethanolamine. In addition, another salicylic acid compound according to the invention is salicylic hydrazide, where the —OR1 moiety in the structure above is replaced by an —NH—NH2 moiety.
The amount of salicylic acid and/or its derivative(s) in the polishing, residue removing and post-CMP cleaning compositions according to the invention can advantageously be from about 0.00001M to about 1M, preferably from about 0.00005M to about 0.5M, for example from about 0.00005M to about 0.001M, from about 0.001M to about 0.01M, from about 0.01M to about 0.1M, or from about 0.1M to about 0.5M. In an alternate embodiment, the amount of salicylic acid and/or its derivative(s) in the compositions according to the invention can advantageously be from about 0.01% to about 25% by weight, preferably from about 0.03% to about 15% by weight, for example from about 0.03% to about 0.5% by weight, from about 0.1% to about 1% by weight, from about 1% to about 15% by weight, from about 0.1% to about 5% by weight, from about 0.5% to about 5% by weight, from about 0.03% to about 1% by weight, or from about 10% to about 15% by weight. Generally, any quantity of salicylic acid and/or its derivative(s), particularly salicylic acid, can act as a chelator while there is typically a certain minimum quantity before the salicylic acid and/or its derivative(s), particularly salicylic acid, can become effective as a corrosion inhibitor. The quantity useful for inhibiting corrosion on a particular substrate with a particular quantity of oxidizer will be readily ascertainable by one of ordinary skill in the art having the benefit of this disclosure.
One particular embodiment comprises adding glacial salicylic acid (aspirin) to a CMP composition, residue removing composition, and or post-CMP cleaning composition in an amount sufficient to chelate metals within the composition and preferably, in an amount sufficient to substantially inhibit corrosion of metal, e.g., copper, on the substrate. A chelating amount may be from about 0.01% to about 2%, typically about 0.01% to about 1%. Corrosion inhibiting amounts are typically from about 4% to about 10%. Intermediate values have both functions.
Aspects of the invention relating to a method for chemically mechanically planarizing-or polishing a metal-containing substrate, comprise contacting a copper-containing substrate with a composition according to the invention for a time and at a temperature sufficient to planarize, and polish copper-containing surface thereof. In a preferred embodiment, compositions useful for this method can include an abrasive such as silica.
Another aspect of the invention relates to a method for cleaning a previously chemically-mechanically planarized or polished copper-containing substrate that includes contacting the polished substrate with a composition according to the invention for a time and at a temperature sufficient to planarize, polish, or clean a copper-containing surface thereof. In a preferred embodiment, compositions useful for this method can be substantially free of an abrasive.
The method of CMP includes contacting the fluid or slurry comprising the oxidizer and salicylic acid and/or its derivative(s) with the substrate under movable conditions, where the fluid or slurry is typically between the substrate and a pad that move relative to one another, to polish substrate material.
Any suitable polishing pad can be used in conjunction with the present invention. In particular, the polishing pad can be woven or non-woven and can comprise any suitable polymer of varying density, hardness, thickness, compressibility, ability to rebound upon compression, and compression modulus. The polishing pad used in conjunction with the present invention preferably has a density of about 0.6 to about 0.95 g/cm3, a Shore A hardness rating of less than about 100 (e.g., about 40 to about 90), a thickness of at least about 0.75 mm (e.g., about 0.75 to about 3 mm), compressibility of about 0 to about 10% (by volume), the ability to rebound to at least about 25% (by volume) (e.g., about 25% to about 100%) after compression at about 35 kPa, and a compression modulus of at least about 1000 kPa. Examples of suitable polymers include polyurethanes, polymelamines, polyethylenes, polyesters, polysulfones, polyvinyl acetates, polyacrylic acids, polyacrylamides, polyvinylchlorides, polyvinylfluorides, polycarbonates, polyamides, polyethers, polystyrenes, polypropylenes, nylons, fluorinated hydrocarbons, and the like, and mixtures, copolymers, and grafts thereof. Preferably, the polishing pad comprises a polyurethane polishing surface. The polishing pad and/or surface can be formed from such materials using suitable techniques recognized in the art, for example, using thermal sintering techniques. Furthermore, the polishing pad formed from such materials can be substantially porous (e.g., having open or closed pores) or substantially non-porous. Porous pads preferably have a pore diameter of about 1 to about 1000 microns and a pore volume of about 15% to about 70%. The polishing pad and/or surface also can be perforated or unperforated to any degree. Preferably, the polishing pad comprises a perforated polishing surface.
The method of post clean treatment involves contacting the substrate, after the CMP process, with the post CMP cleaner under conditions to remove the CMP slurry.
| Number | Date | Country | |
|---|---|---|---|
| 60516736 | Nov 2003 | US |
