Composition and method for cobalt chemical mechanical polishing

Abstract

A chemical mechanical polishing composition for polishing a substrate having a cobalt layer comprises: a water-based liquid carrier; cationic silica abrasive particles dispersed in the liquid carrier; and a triazole compound, wherein the polishing composition has a pH greater than about 6, and the cationic silica abrasive particles have a zeta potential of at least 10 mV. The triazole compound is not benzotriazole or a benzotriazole compound. A method for chemically mechanically polishing a substrate including a cobalt layer comprises: contacting the substrate with the polishing composition described above; moving the polishing composition relative to the substrate; and abrading the substrate to remove a portion of the cobalt layer from the substrate and thereby polishing the substrate.

Description

Background Technology

[0001] Tungsten plugs, tungsten interconnects, copper interconnects, and dual damascene processes are back-end of the line (BEOL) processes, which have long been used to form the network of metal wires connecting transistors in conventional semiconductor devices. In these processes, tungsten or copper metal is deposited into openings formed in a dielectric material (e.g., TEOS). Chemical mechanical polishing (CMP) is used to remove excess tungsten or copper from the dielectric, thereby forming tungsten or copper plugs and / or interconnects therein. Interlayer dielectric (ILD) materials (such as TEOS) are deposited between the metal interconnect layers to provide electrical insulation between the layers.

[0002] As transistor sizes continue to shrink, the use of conventional interconnect technologies has become increasingly challenging. Recently, cobalt has emerged as a leading candidate to replace tantalum / tantalum nitride barrier laminates in copper interconnects. Cobalt has also been actively investigated as a replacement for tungsten in various BEOL applications. With the potential introduction of cobalt as a barrier layer and / or tungsten plug and / or interconnect replacement, there is an emerging demand for CMP pastes capable of planarizing cobalt-containing substrates.

[0003] Generally, commercially available CMP pastes designed for removing tungsten, copper, or other metal layers are ill-equipped for polishing cobalt, especially in advanced node devices. For example, Co tends to be chemically reactive and susceptible to various corrosion problems during CMP processes. CMP pastes are needed that can remove cobalt films and / or effectively planarize cobalt-containing substrates without causing corresponding cobalt corrosion. Summary of the Invention

[0004] A chemical mechanical polishing composition for polishing a substrate having a cobalt layer is disclosed. The polishing composition comprises, is substantially composed of, or consists of: a water-based liquid carrier; cationic silica abrasive particles dispersed in the liquid carrier, wherein the cationic silica abrasive particles have a zeta potential of at least 10 mV in the polishing composition; a triazole compound, wherein the triazole compound is not a benzotriazole or benzotriazole compound, and wherein the polishing composition has a pH greater than about 6. In one embodiment, the silica abrasive particles comprise colloidal silica particles, and the triazole compound comprises a triazolepyridine compound, such as 1H-1,2,3-triazolo[4,5-b]pyridine. A method for chemical mechanical polishing a substrate including a cobalt layer is further disclosed. The method may include: contacting the substrate with the polishing composition described above; moving the polishing composition relative to the substrate; and abrading the substrate to remove a portion of the cobalt from the substrate and thereby polishing the substrate. The method may further include removing a portion of the dielectric layer from the substrate. Detailed Implementation

[0005] A chemical mechanical polishing composition for polishing a substrate having a cobalt layer is disclosed. The polishing composition comprises, is substantially composed of, or consists of: a water-based liquid carrier; cationic silica abrasive particles dispersed in the liquid carrier; and a triazole compound. The polishing composition has a pH greater than about 6, and the cationic silica abrasive particles in the polishing composition have a zeta potential of at least 10 mV. The triazole compound is not benzotriazole or a benzotriazole compound. In one embodiment, the silica abrasive particles comprise colloidal silica particles treated with an aminosilane compound, and the triazole compound comprises a triazolepyridine compound, such as 1H-1,2,3-triazolo[4,5-b]pyridine.

[0006] It should be understood that the disclosed CMP compositions are advantageously suited for bulk cobalt removal and / or buff CMP operations. Bulk removal operations may require higher cobalt removal rates, while buff operations may require lower defect levels and / or more stringent corrosion control. The disclosed CMP compositions are also advantageously suited for single-step cobalt CMP operations. While the disclosed embodiments are particularly well-suited for cobalt buff operations, they are not intended to be limited to any particular cobalt CMP operation.

[0007] The polishing composition contains an abrasive comprising metal oxide particles suspended in a liquid carrier. The abrasive may substantially comprise suitable metal oxide particles, for example, colloidal silica particles and / or pyrolytic silica particles. As used herein, the term colloidal silica particles refers to silica particles prepared via a wet process rather than a pyrochemical or flame hydrolysis process that typically produces structurally distinct particles. Such colloidal silica particles may be aggregated or non-aggregated. Non-aggregated particles are individual discrete particles that may be spherical or nearly spherical in shape, but may also have other shapes (such as, typically, elliptical, square, or rectangular cross-sections). Aggregated particles are particles in which multiple discrete particles cluster together or combine to form aggregates with typically irregular shapes.

[0008] Colloidal silica can be precipitated or condensed silica, which can be prepared using any method known to those skilled in the art, such as by sol-gel method or by silicate ion exchange. Condensed silica particles are often prepared by condensing Si(OH)4 to form substantially spherical particles. The precursor Si(OH)4 can be obtained, for example, by hydrolyzing a high-purity alkoxysilane or by acidifying an aqueous silicate solution. Such abrasive particles can be prepared, for example, according to U.S. Patent No. 5,230,833, or can be obtained from, for example, any of the following commercial suppliers: EKA Chemicals, Fuso Chemical Company, Nalco, DuPont, Bayer, Applied Research, Nissan Chemical, and Clariant.

[0009] Pyrolytic silica is produced via a flame hydrolysis process, in which a suitable feedstock vapor (such as silicon tetrachloride) is burned in a flame of hydrogen and oxygen. During the combustion process, generally spherical molten particles are formed, the diameter of which can be varied by process parameters. These molten spheres (often called primary particles) fuse together by colliding at their contact points to form branched, three-dimensional chain-like aggregates. Pyrolytic silica abrasives are commercially available from many suppliers, including, for example, Cabot Corporation, Evonic, and Wacker Chemie.

[0010] Abrasive particles can have virtually any suitable particle size. In industry, various methods can be used to define the particle size of particles suspended in a liquid carrier. For example, particle size can be defined as the diameter of the smallest sphere surrounding the particle, and several commercially available instruments can be used to measure particle size, including, for example, the CPS disc centrifuge, the Model DC24000HR (available from CPS Instruments, Prairieville, Louisiana), or Malvern. of Abrasive particles may have an average particle size of about 5 nm or greater (e.g., about 10 nm or greater, about 20 nm or greater, or about 30 nm or greater). Abrasive particles may have an average particle size of about 200 nm or less (e.g., about 160 nm or less, about 140 nm or less, about 120 nm or less, or about 100 nm or less). Therefore, it should be understood that abrasive particles may have an average particle size within the range defined by any two of the foregoing endpoints. For example, abrasive particles may have an average particle size in the range of about 5 nm to about 200 nm (e.g., about 10 nm to about 160 nm, about 20 nm to about 140 nm, about 20 nm to about 120 nm, or about 20 nm to about 100 nm).

[0011] Polishing compositions may comprise virtually any suitable amount of abrasive particles. If a polishing composition contains too little abrasive, the composition may not exhibit an adequate removal rate. Conversely, if a polishing composition contains too much abrasive, the polishing composition may exhibit unsatisfactory polishing performance and / or may be uneconomical and / or may lack stability. A polishing composition may comprise about 0.01% by weight or more of abrasive particles (e.g., about 0.05% by weight or more). A polishing composition may comprise about 0.1% by weight or more (e.g., about 0.2% by weight or more, about 0.3% by weight or more, or 0.5% by weight or more) of abrasive particles. The concentration of abrasive particles in a polishing composition is generally less than about 20% by weight, and more typically about 10% by weight or less (e.g., about 5% by weight or less, about 3% by weight or less, about 2% by weight or less, or about 1.5% by weight or less, or about 1% by weight or less). It should be understood that the concentration of abrasive particles in the polishing composition may be defined by any of the foregoing endpoints. For example, the concentration of abrasive particles in the polishing composition may be in the range of about 0.01 wt% to about 20 wt%, and more preferably about 0.05 wt% to about 10 wt% (e.g., about 0.1 wt% to about 5 wt%, about 0.1 wt% to about 3 wt%, about 0.1 wt% to about 2 wt%, about 0.2 wt% to about 2 wt%, about 0.2 wt% to about 1.5 wt%, or about 0.2 wt% to about 1 wt%).

[0012] In embodiments where the abrasive particles comprise silica (such as colloidal or igneous silica), the silica particles may have a positive charge in the polishing composition. The charge on dispersed particles (such as silica particles) is commonly referred to in the art as the zeta potential (or zeta potential). The zeta potential of a particle is the potential difference between the charge of the ions surrounding the particle and the charge of the bulk solution of the polishing composition (e.g., the liquid carrier and any other components dissolved therein). Therefore, positively charged silica abrasive particles (i.e., cationic silica abrasive particles) will have a positive zeta potential at their operating pH. The zeta potential typically depends on the pH of the aqueous medium. For a given composition, the isoelectric point of the particles is defined as a pH at which the zeta potential is zero. As the pH increases or decreases from the isoelectric point, the surface charge (and therefore the zeta potential) decreases or increases accordingly (to negative or positive zeta potential values). The zeta potential of dispersed abrasive particles (such as dispersed abrasive particles in the disclosed polishing composition) can be obtained using commercially available instruments such as the Zetasizer from Malvern Instruments, the ZetaPlus zeta potential analyzer from Brookhaven Instruments, and / or an electroacoustic spectrometer from Dispersion Technologies, Inc.

[0013] In some embodiments, the cationic silica abrasive particles have an isoelectric point greater than pH 7. For example, the abrasive particles may have an isoelectric point greater than pH 8 (e.g., greater than pH 8.5 or greater than pH 9). As described in more detail below, the abrasive particles may optionally comprise colloidal silica particles treated with a nitrogen-containing compound such as an aminosilane compound.

[0014] In some embodiments, cationic silica abrasive particles have a zeta potential of about 10 mV or greater (e.g., about 15 mV or greater, about 20 mV or greater, about 25 mV or greater, or about 30 mV or greater) in the polishing composition (e.g., pH greater than about 6 or pH range between about 6 and about 8). Cationic silica abrasive particles may have a zeta potential of about 50 mV or less (e.g., about 45 mV or less, or about 40 mV or less) in the polishing composition (e.g., pH greater than about 6 or pH range between about 6 and about 8). It should be understood that cationic silica abrasive particles may have a zeta potential within a range defined by either of the foregoing endpoints. For example, cationic silica abrasive particles may have a zeta potential in the range of about 10 mV to about 50 mV (e.g., about 10 mV to about 45 mV, or about 20 mV to about 40 mV) in the polishing composition (e.g., pH greater than about 6 or pH range between about 6 and about 8).

[0015] In some embodiments, the cationic silica abrasive particles may comprise colloidal silica particles treated with an aminosilane compound such that the treated abrasive particles have a zeta potential of about 10 mV or greater (e.g., about 15 mV or greater, about 20 mV or greater, about 25 mV or greater, or about 30 mV or greater) in the polishing composition (e.g., pH greater than about 6, greater than about 7, greater than about 7.5, or greater than about 8). In some of these embodiments, the abrasive particles comprise colloidal silica particles treated with a quaternary aminosilane compound. Such cationic colloidal silica particles may be obtained, for example, by treating the particles with at least one aminosilane compound disclosed in commonly assigned U.S. Patents 7,994,057 and 9,028,572 or U.S. Patent 9,382,450, each of which is incorporated herein by reference in its entirety. Colloidal silica particles having a zeta potential of about 10 mV or greater in the polishing composition can also be obtained by incorporating chemical species such as aminosilane compounds into the colloidal silica particles as disclosed in commonly assigned U.S. Patent 9,422,456, which is incorporated herein by reference in its entirety.

[0016] It should be understood that the example cationic colloidal silica particles can be processed using any suitable treatment method to obtain cationic colloidal silica particles. For example, a quaternary aminosilane compound and colloidal silica can be simultaneously added to some or all of the other components in the polishing composition. Alternatively, the colloidal silica can be treated with a quaternary aminosilane compound (e.g., by heating a mixture of colloidal silica and aminosilane) before being mixed with the other components of the polishing composition.

[0017] In some embodiments, the cationic silica abrasive particles may possess a permanent positive charge. A permanent positive charge means that the positive charge on the silica particles is not easily reversed, for example, by rinsing, dilution, filtration, or the like. A permanent positive charge may result from, for example, the covalent bonding of a cationic compound with colloidal silica. A permanent positive charge is the opposite of a reversible positive charge, which may result from, for example, the electrostatic interaction between a cationic compound and colloidal silica.

[0018] Nevertheless, as used herein, a permanent positive charge of at least 10 mV means that the zeta potential of the colloidal silica particles remains above 10 mV after the following three-step ultrafiltration test. A volume of polishing composition (e.g., 200 ml) is passed through a Millipore Ultracell regenerated cellulose ultrafiltration disc (e.g., with a MW cutoff of 100,000 Daltons and a pore size of 6.3 nm). The remaining dispersion (the dispersion retained by the ultrafiltration disc) is collected and replenished to the original volume with pH-adjusted deionized water. The pH of the deionized water is adjusted to the original pH of the polishing composition using a suitable inorganic acid (such as nitric acid). This procedure is repeated for a total of three ultrafiltration cycles (each of which includes an ultrafiltration step and a replenishment step). The zeta potential of the polishing composition after three ultrafiltrations and replenishments is then measured and compared to the zeta potential of the original polishing composition. The three-step ultrafiltration test is further described in detail in Example 10 of commonly assigned U.S. Patent 9,422,456, which is incorporated herein by reference in its entirety.

[0019] Liquid carriers are used to facilitate the application of abrasives and any optional chemical additives to the surface of a substrate to be polished (e.g., planarized). Liquid carriers can be any suitable carrier (e.g., solvent), including lower alcohols (e.g., methanol, ethanol, etc.), ethers (e.g., diethanolamine, ethanol ... Alkane, tetrahydrofuran, etc.), water, and mixtures thereof. Preferably, the liquid carrier contains water (more preferably deionized water), is substantially composed of water (more preferably deionized water), or is composed of water (more preferably deionized water).

[0020] The polishing composition is typically neutral, having a pH in the range of about 5 to about 9. For example, when measured at 1 atmosphere and 25°C, the polishing composition may have a pH of about 6 or greater (e.g., about 6.5 or greater, about 7 or greater, or about 7.5 or greater). The polishing composition may further have a pH of about 9 or less (e.g., about 8 or less, or about 7.5 or less). The polishing composition may therefore have a pH in the range defined by any two of the above endpoints. For example, the pH may be in the range of about 6 to about 9 (e.g., about 6 to about 8, about 6.5 to about 8, about 7 to about 8.5, or about 7 to about 8). The pH of the polishing composition can be achieved and / or maintained by any suitable means. The polishing composition may substantially include any suitable pH adjuster or buffer system. For example, suitable pH adjusters may include nitric acid, sulfuric acid, phosphoric acid and the like, and organic acids such as acetic acid and lactic acid. Suitable buffers may include phosphates, ammonium salts and the like.

[0021] The polishing composition further includes an inhibitor of cobalt etching and / or corrosion. It is known that cobalt metal is susceptible to corrosion in acidic and neutral environments. The cobalt inhibitor is designed to reduce the rate of dissolution of cobalt metal in the CMP composition. In some embodiments, the cobalt inhibitor comprises a triazole compound. Preferred triazole compounds include triazole pyridine (TAP) compounds, such as 1H-1,2,3-triazolo[4,5,b]pyridine, 1-acetyl-1H-1,2,3-triazolo[4,5,b]pyridine, 3H-[1,2,3]triazolo[4,5-c]pyridine, and 2-(1,2,4-triazol-3-yl)pyridine. The most preferred copper inhibitor is 1H-1,2,3-triazolo[4,5,b]pyridine. The structure of 1H-1,2,3-triazolo[4,5,b]pyridine is shown below.

[0022]

[0023] While cobalt inhibitors may include triazole compounds such as triazole pyridine compounds, it should be understood that cobalt inhibitors do not include benzotriazole or benzotriazole compounds (such as benzotriazole, 5-methyl-1H-benzotriazole, or 1H-benzotriazole-1-methanol). Benzotriazole (BTA) is a well-known and highly effective copper corrosion inhibitor commonly used in commercial copper CMP slurries. As shown in Example 1 below, BTA and certain BTA compounds can act as cobalt inhibitors in CMP polishing compositions. However, it has been found that the use of BTA or BTA compounds in CMP polishing compositions may be disadvantageous for at least the following reasons. These compounds are believed to form a firmly adhered organic film to the cobalt substrate (presumably inhibiting cobalt corrosion). The presence of this firmly adhered film has been found to result in significant organic surface residue defects on the wafer after CMP post-cleaning operations (because removal of this film has proven difficult). This surface defect has been observed to persist even after multiple CMP post-cleaning steps using alkaline cleaners.

[0024] As described above, cobalt inhibitors preferably comprise triazole pyridine compounds. Those skilled in the art will readily understand that triazole pyridine compounds comprise a triazole group bonded to a pyridine ring. In some embodiments, the pyridine ring and the triazole group share primary and secondary carbon atoms (and are therefore bonded together at the primary and secondary carbon atoms). In contrast, benzotriazole compounds comprise a triazole group bonded to a benzene ring. Triazole pyridine compounds do not include a benzene ring.

[0025] The above disclosure that the cobalt inhibitor does not include benzotriazole or benzotriazole compounds is not intended to imply that the polishing composition must be free of benzotriazole or benzotriazole compounds. Rather, in embodiments that include multiple triazole compounds, it should be understood that at least one of the triazole compounds is not benzotriazole or benzotriazole compounds. For example, it should be understood that in some embodiments, in addition to the triazole compound cobalt inhibitor described above, the polishing composition may additionally include low amounts of benzotriazole or benzotriazole compounds (e.g., less than 50 ppm, or less than 20 ppm, or less than 10 ppm, or even less than 5 ppm).

[0026] The amount of cobalt inhibitor compound in the polishing composition can vary depending on the specific compound used, whether an oxidant is used, the pH of the polishing composition, and other factors. When the preferred cobalt inhibitor is a triazole pyridine compound and the pH of the composition is neutral (e.g., about 5 to about 9), the cobalt inhibitor can be present in the polishing composition in an amount ranging from about 10 ppm to about 2000 ppm by weight of the composition. In some embodiments, the polishing composition may include about 10 ppm or more of a triazole pyridine compound (e.g., about 20 ppm or more, about 50 ppm or more, or about 100 ppm or more). The polishing composition may also include about 2000 ppm or less of a triazole pyridine compound (e.g., about 1000 ppm or less, about 700 ppm or less, or about 500 ppm or less). Therefore, it should be understood that the triazole pyridine cobalt etching inhibitor can be present in the polishing composition at concentrations defined by either of the foregoing endpoints. For example, the polishing composition may include about 20 ppm to about 1000 ppm of a triazole pyridine compound (e.g., about 50 ppm to about 1000 ppm, about 50 to about 500 ppm, or about 100 ppm to about 500 ppm).

[0027] The polishing composition preferably does not contain oxidants including per-compounds. In other words, it is preferred that the per-compound is not present in the polishing composition and is not intentionally added to it. In such embodiments, the concentration of the per-compound oxidant in the polishing composition is substantially zero (e.g., less than 1 ppm by weight, less than 0.3 ppm by weight, or less than 0.1 ppm by weight). Per-compounds, as defined herein, are compounds containing at least one peroxy group (-O--O-) or compounds containing a halogen element in its highest oxidation state. Examples of compounds containing at least one peroxy group include (but are not limited to): hydrogen peroxide and its adducts, such as urea hydrogen peroxide, percarbonate, perborate, perboric acid; organic peroxides, such as benzoyl peroxide, peracetic acid, and di-tert-butyl peroxide; monopersulfate (SO5) ＝ ); persulfate (S2O8)＝ ); and sodium peroxide. Examples of compounds containing halogen elements in their highest oxidation state include (but are not limited to): periodic acid, periodate, perbromic acid, perbromate, perchloric acid, and perchlorate.

[0028] It is known that peroxides (including hydrogen peroxide and its adducts) react chemically with triazole compounds, including the aforementioned cobalt inhibitor compounds. Therefore, the elimination of such peroxides can improve the chemical stability of the cobalt inhibitor and advantageously improve the shelf life of the polishing composition.

[0029] The polishing composition may optionally (but not necessarily) include an oxidant that does not contain peroxides (a non-peroxide oxidant). Such a non-peroxide oxidant may be selected from nitrogen-containing organic oxidants, such as nitro compounds, nitroso compounds, N-oxide compounds, oxime compounds, and combinations thereof. For example, optional oxidants may include aryl nitro compounds, aryl nitroso compounds, aryl N-oxide compounds, aryl oxime compounds, heteroaryl nitro compounds, heteroaryl nitroso compounds, heteroaryl N-oxide compounds, heteroaryl oxime compounds, and combinations thereof.

[0030] In optional embodiments including a non-per oxidizing agent, the oxidizing agent may be present at substantially any suitable concentration. The oxidizing agent may be present in the polishing composition at a concentration of about 1 mM or greater, such as about 5 mM or greater, about 10 mM or greater, about 20 mM or greater, about 30 mM or greater, about 40 mM or greater, or about 50 mM or greater. The oxidizing agent may also be present in the polishing composition at a concentration of about 100 mM or less, such as about 90 mM or less, about 80 mM or less, about 70 mM or less, or about 60 mM or less. It should be understood that the oxidizing agent may be present in the polishing composition at concentrations defined by any two of the foregoing endpoints. For example, the oxidizing agent may be present in the polishing composition at concentrations ranging from about 1 mM to about 100 mM (e.g., about 5 mM to about 90 mM, about 10 mM to about 80 mM, about 20 mM to about 70 mM, or about 20 mM to about 60 mM).

[0031] The polishing composition may further optionally (but indeed must) include a cobalt polishing accelerator. The cobalt accelerator may be any suitable cobalt accelerator selected from the following: N-di(carboxyalkyl)amine, N-di(hydroxyalkyl)amine, N,N-di(hydroxyalkyl)-N-carboxyalkylamine, dicarboxylated heterocycle, heterocyclic alkyl-α-amino acid, N-aminoalkyl amino acid, unsubstituted heterocycle, alkyl-substituted heterocycle, carboxylic acid, dicarboxylic acid, tricarboxylic acid, alkylamine, N-aminoalkyl-α-amino acid, and combinations thereof. For example, the polishing composition may optionally include a cobalt accelerator selected from: iminodiacetic acid (“IDA”), N-(2-acetamido)iminodiacetic acid (“ADA”), N-methylimidazolium, pyridinecarboxylic acid, pyridinedicarboxylic acid, 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid, glycine, bicine, triethylamine (TEA) (“TEA”), etidronic acid, N-methylmorpholine, malonic acid, 2-pyridine sulfonate, citric acid, and combinations thereof.

[0032] In optional embodiments including a cobalt accelerator, the cobalt accelerator may be present in the polishing composition at any suitable concentration. In some optional embodiments, the cobalt accelerator may be present in the polishing composition at a concentration of about 5 mM or greater (e.g., about 10 mM or greater, about 20 mM or greater, or about 40 mM or greater). The cobalt accelerator may be present in the polishing composition at a concentration of about 100 mM or less (e.g., about 80 mM or less, about 60 mM or less, or about 50 mM or less). The cobalt accelerator may be present in the polishing composition at a concentration defined by any of the foregoing endpoints, for example, in the range of about 5 mM to about 100 mM, about 10 mM to about 80 mM, or about 20 mM to about 60 mM.

[0033] The polishing composition may optionally further include a biocide. The biocide may include any suitable biocide, such as isothiazolinone biocides, such as those available from Dow Chemical Company. Biocide. The polishing composition may comprise essentially any suitable amount of biocide. For example, some embodiments may comprise about 1 ppm to about 1000 ppm, such as about 10 ppm to about 500 ppm of biocide. The disclosed embodiments are explicitly not limited to the use of any particular biocide compound or concentration.

[0034] Polishing compositions can be prepared using any suitable technique, many of which are known to those skilled in the art. Polishing compositions can be prepared in batch or continuous processes. Generally, polishing compositions can be prepared by combining their components in any order. As used herein, the term "component" includes individual ingredients (e.g., abrasive particles, cobalt inhibitors, etc.).

[0035] For example, colloidal silica and quaternary aminosilane compounds can be mixed in an aqueous liquid carrier. This mixture can optionally be heated (e.g., to a temperature of about 50°C to 80°C) to promote the bonding of the aminosilane compound with the colloidal silica. Other components (such as cobalt inhibitors and biocides) can then be added and mixed using any method capable of incorporating the components into the polishing composition. Alternatively, the polishing composition can be prepared by mixing the components at the surface of the substrate (e.g., on a polishing pad) during CMP operations.

[0036] The polishing composition of the present invention can also be provided as a concentrate intended to be diluted with an appropriate amount of water before use. In such an embodiment, the polishing composition concentrate may include abrasive particles, a cobalt inhibitor, optionally a biocide, and water, the amounts of which are such that when the concentrate is diluted with an appropriate amount of water, each component of the polishing composition will be present in the polishing composition in an amount within the appropriate range described above for each component. For example, the abrasive particles and the cobalt inhibitor may be present in the polishing composition in an amount approximately twice (e.g., approximately three times, four times, five times, or ten times) the concentrations described above for each component, such that when the concentrate is diluted with equal volumes of water (e.g., 1, 2, 3, 4, or even 9 volumes of water, respectively), each component will be present in the polishing composition in an amount within the range described above for each component. Furthermore, as those skilled in the art will understand, the concentrate may contain an appropriate ratio of water present in the final polishing composition to ensure that the other components are at least partially or completely dissolved in the concentrate.

[0037] While the polishing composition of the present invention can be used to polish any substrate, it is particularly suitable for polishing substrates containing at least one cobalt-containing layer. The substrate may further include a dielectric layer comprising a metal oxide, such as a silicon oxide layer derived from tetraethyl orthosilicate (TEOS), a porous metal oxide, a porous or non-porous carbon-doped silicon oxide, a fluorine-doped silicon oxide, glass, an organic polymer, a fluorinated organic polymer, or any other suitable high-k or low-k insulating layer.

[0038] The polishing method of the present invention is particularly suitable for use in conjunction with a chemical mechanical polishing (CMP) apparatus. Typically, the apparatus includes: a pressure plate that is in motion during use and has a speed generated by tracked, linear, or circular motion; a polishing pad that contacts the pressure plate and moves with the pressure plate during motion; and a carrier that holds a substrate to be polished by contacting the surface of the polishing pad and moving relative to it. Polishing of the substrate is performed by placing the substrate in contact with the polishing pad and the polishing composition of the present invention, and then moving the polishing pad relative to the substrate to abrade at least a portion of the substrate (such as cobalt and dielectric materials as described herein) to polish the substrate.

[0039] In some embodiments, optimal planarization is achieved when the polishing rates of cobalt and the dielectric material are similar. For example, in some embodiments, the selectivity of cobalt to the dielectric material can be in the range of about 1:10 to about 10:1. In some embodiments, the polishing rate of the dielectric material can be greater than the polishing rate of cobalt, such that the selectivity of cobalt to the dielectric material can be less than 1:1 (e.g., in the range of 1:10 to about 1:1).

[0040] A chemical mechanical polishing composition can be used with any suitable polishing pad (e.g., a polishing surface) to planarize or polish a substrate. Suitable polishing pads include, for example, woven and non-woven polishing pads. Furthermore, suitable polishing pads can contain any suitable polymer having various densities, hardness, thicknesses, compressibility, compression resilience, and compressive modulus. Suitable polymers include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbons, polycarbonates, polyesters, polyacrylates, polyethers, polyethylene, polyamides, polyurethanes, polystyrene, polypropylene, their co-formations, and mixtures thereof.

[0041] The present invention is further illustrated by the following embodiments.

[0042] Embodiment (1) presents a chemical mechanical polishing composition for polishing a cobalt-containing substrate, the polishing composition comprising: (i) a water-based liquid carrier; (ii) cationic silica abrasive particles dispersed in the liquid carrier, the cationic silica abrasive particles having a zeta potential of at least 10 mV; (iii) a triazole compound, wherein the triazole compound is not a benzotriazole or benzotriazole compound; wherein the polishing composition has a pH greater than about 6.

[0043] Embodiment (2) presents the composition according to Embodiment (1), wherein the triazole compound is a triazole pyridine compound.

[0044] Embodiment (3) presents a composition according to Embodiment (2), wherein the triazolylpyridine compound is 1H-1,2,3-triazolo[4,5,b]pyridine, 1-acetyl-1H-1,2,3-triazolo[4,5,b]pyridine, 3H-[1,2,3]triazolo[4,5-c]pyridine, 2-(1,2,4-triazol-3-yl)pyridine, or a mixture thereof.

[0045] Embodiment (4) presents the composition according to Embodiment (2), wherein the triazole pyridine compound is 1H-1,2,3-triazolo[4,5,b]pyridine.

[0046] Embodiment (5) presents a composition according to any one of Embodiments (2) to (4) comprising about 50 ppm to about 500 ppm of the triazolylpyridine compound.

[0047] Embodiment (6) presents a composition according to any one of Embodiments (1) to (5), wherein the polishing composition is substantially free of per-compound oxidants.

[0048] Embodiment (7) presents a composition according to any one of Embodiments (1) to (6) having a pH of about 6 to about 8.

[0049] Embodiment (8) presents a composition according to any one of Embodiments (1) to (7), wherein the cationic silica abrasive particles have an isoelectric point greater than about 9.

[0050] Embodiment (9) presents a composition according to any one of Embodiments (1) to (8), wherein the cationic silica abrasive particles comprise colloidal silica particles having a permanent positive charge of at least 20 mV at a pH greater than about 6.

[0051] Embodiment (10) presents a composition according to any one of Embodiments (1) to (9) comprising less than about 2% by weight of the cationic silica abrasive particles.

[0052] Embodiment (11) presents a method for chemically and mechanically polishing a substrate including a cobalt layer, the method comprising: (a) contacting the substrate with a polishing composition comprising: (i) a water-based liquid carrier; (ii) cationic silica abrasive particles dispersed in the liquid carrier, the cationic silica abrasive particles having a zeta potential of at least 10 mV; (iii) a triazole compound, wherein the triazole compound is not a benzotriazole or benzotriazole compound; and wherein the polishing composition has a pH greater than about 6; (b) moving the polishing composition relative to the substrate; and (c) grinding the substrate to remove a portion of the cobalt layer from the substrate and thereby polishing the substrate.

[0053] Embodiment (12) presents the method according to Embodiment (11), wherein the triazole compound is a triazole pyridine compound.

[0054] Embodiment (13) presents the method according to Embodiment (12), wherein the triazolylpyridine compound is 1H-1,2,3-triazolo[4,5,b]pyridine, 1-acetyl-1H-1,2,3-triazolo[4,5,b]pyridine, 3H-[1,2,3]triazolo[4,5-c]pyridine, 2-(1,2,4-triazol-3-yl)pyridine, or a mixture thereof.

[0055] Embodiment (14) presents the method according to Embodiment (12), wherein the triazolylpyridine compound is 1H-1,2,3-triazolo[4,5,b]pyridine.

[0056] Embodiment (15) presents a method according to any one of Embodiments (12) to (14), wherein the polishing composition comprises about 50 ppm to about 500 ppm of the triazole pyridine compound.

[0057] Embodiment (16) presents a method according to any one of Embodiments (11) to (15), wherein the polishing composition is substantially free of per-compound oxidants.

[0058] Embodiment (17) presents a method according to any one of Embodiments (11) to (16), wherein the polishing composition has a pH of about 6 to about 8.

[0059] Embodiment (18) presents a method according to any one of embodiments (11) to (17), wherein the cationic silica abrasive particles have an isoelectric point greater than about 9.

[0060] Embodiment (19) presents a method according to any one of Embodiments (11) to (18), wherein the cationic silica abrasive particles comprise colloidal silica particles having a permanent positive charge of at least 20 mV at a pH greater than about 6.

[0061] Embodiment (20) presents a method according to any one of embodiments (11) to (19) comprising less than about 2% by weight of the cationic silica abrasive particles.

[0062] Embodiment (21) presents a method according to any one of embodiments (11) to (20), wherein the substrate further comprises a dielectric layer, and wherein the polishing in (c) further removes a portion of the dielectric layer from the substrate.

[0063] Implementation (22) presents the method according to implementation (21), wherein the removal rate of the dielectric layer in (c) is greater than the removal rate of cobalt in (c).

[0064] Embodiment (23) presents the method according to Embodiment (22), wherein the dielectric layer is tetraethyl orthosilicate (TEOS).

[0065] Embodiment (24) presents a chemical mechanical polishing composition for polishing a cobalt-containing substrate. The polishing composition comprises: a water-based liquid carrier; cationic silica abrasive particles dispersed in the liquid carrier; cationic silica abrasive particles having a zeta potential of at least 10 mV in the polishing composition; a triazolylpyridine compound; and wherein the polishing composition has a pH greater than about 6.

[0066] The following examples further illustrate the invention, but should not be construed as limiting its scope in any way.

[0067] Example 1

[0068] Various polishing compositions were prepared (Control A and Examples 1-12). Examples 1-12 polishing compositions comprise various azole compounds. Each of the thirteen polishing compositions was prepared by adding appropriate amounts of cationic colloidal silica particles having an average particle size of 50 nm to the respective mixtures to achieve a final concentration of 0.5% by weight of cationic colloidal silica. The cationic colloidal silica particles were prepared as described in Example 7 of U.S. Patent 9,382,450. Each of the final compositions further comprised 1.68 mM of the corresponding azole compound, 2 mM of tris(hydroxymethyl)aminomethane, 125 ppm of Kordek biocide, at pH 7.1. Control A did not include azole compounds. Specific azole compounds used in each of Examples 1-12 are provided in Table 1. Each of the compositions (Control A and Examples 1-12) has a zeta potential of approximately 25 mV at pH 7.1.

[0069] The cobalt etch rate of each of the above polishing compositions was evaluated. This example demonstrates the effectiveness of certain azole compounds (especially triazole compounds) as cobalt etch inhibitors. To obtain the cobalt etch rate of each polishing composition, the polishing composition was first heated to 45°C, and then a wafer with a cobalt layer of two square centimeters was immersed in the polishing composition (cobalt side up) for 5 minutes. The cobalt removal rate was determined by resistivity measurements performed before and after immersion in the polishing composition.

[0070] The cobalt etching rates are shown in Table 1. As mentioned above, control A does not include azole compounds. The specific azole compounds used in each of the example compositions 1 to 12 are shown in the table.

[0071] Table 1

[0072]

[0073] As the results are clearly presented in Table 1, the examples 1-8 demonstrate A cobalt etching rate of / minute or less, which is less than half the cobalt etching rate of control A (without inhibitor). Compositions 9-12 exhibit The cobalt etching rate is 1 / min or greater, which is similar to the cobalt etching rate of control A.

[0074] Example 2

[0075] In this embodiment, the polishing rate and cleaning ability (defect rate) of cobalt and TEOS were evaluated for polishing compositions 1-7 from Examples 1. This embodiment demonstrates that the use of a triazolylpyridine cobalt inhibitor resulted in the lowest number of defects after the CMP post-cleaning step. The cobalt and TEOS polishing rate was obtained by polishing a blanket-coated cobalt and TEOS wafer. At a pressure of 1.5 psi, a platen speed of 93 rpm, and a head speed of 87 rpm, using... The wafer was polished using CMP polishing tools and a Fujibo H7000 polishing pad. The slurry flow rate was 200 ml / min. After polishing, the cobalt wafer was cleaned for 60 seconds using an ONTRAK cleaner with a K8160-1 (available from Cabot Microelectronics) in each of two brush holders. Defect counts were collected using a Surfscan SP1 at a threshold of 0.16 μm. Defect images were collected using a scanning electron microscope, and defect classification was performed by visual examination of the images obtained. The observed defects were mainly organic surface residues. The cobalt and TEOS polishing rates and defect data are shown in Table 2.

[0076] Table 2

[0077]

[0078] As the results illustrated in Table 2 clearly show, the use of triazolylpyridine inhibitors resulted in the fewest number of defects, indicating that these compounds are more readily removed from the cobalt substrate during the post-CMP cleaning step. The use of benzotriazole and benzotriazole compounds as cobalt inhibitors resulted in a very large number of organic defects on the cobalt surface. Even with multiple post-CMP cleaning steps, the number of these defects could not be reduced.

[0079] All references cited in this article (including publications, patent applications and patents) are incorporated herein by reference as if each reference were individually and specifically cited for reference and as fully described herein.

[0080] The terms “a,” “an,” and “the,” and similar designations used in describing the scope of the invention (particularly the scope of the appended claims) should be understood to include both singular and plural forms unless otherwise stated herein or the context clearly contradicts them. The terms “comprising,” “having,” “including,” and “containing” should be understood as open-ended terms (i.e., meaning “including, but not limited to”) unless otherwise stated. The enumeration of numerical ranges herein is merely a shorthand method of individually referring to each independent value falling within that range, unless otherwise stated herein, and each independent value is introduced in the specification as if it were individually enumerated herein. All methods described herein can be performed in any suitable order unless otherwise stated herein or clearly contradicted by the context. The use of any and all instances or exemplary language (e.g., “for example, such as”) provided herein is merely for better illustrating the invention and not for limiting the scope of the invention, unless otherwise stated. No language in the specification should be construed as necessary to indicate any non-claimed element as essential to the practice of the invention.

[0081] Preferred embodiments of the invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors encourage those skilled in the art to adopt such variations appropriately, and the inventors encourage the invention to be practiced in ways different from those specifically described herein. Therefore, the invention includes all modifications and equivalents of the subject matter listed in the appended claims as permitted by applicable law. Furthermore, the invention covers any combination of the foregoing elements in all possible variations, unless otherwise stated herein or clearly contradicted by the context.

Claims

1. A chemical mechanical polishing composition for polishing a cobalt-containing substrate, the polishing composition comprising: Water-based liquid carriers; Cationic silica abrasive particles dispersed in the liquid vehicle, wherein The cationic silica abrasive particles contain colloidal silica particles that have a permanent positive charge of at least 20 mV at a pH greater than 6. A triazole compound, wherein the triazole compound is a triazole pyridine compound selected from 1H-1,2,3-triazolo[4,5,b]pyridine and 1-acetyl-1H-1,2,3-triazolo[4,5,b]pyridine; and The polishing composition has a pH greater than 6.

2. The composition of claim 1, wherein, The triazolylpyridine compound is 1H-1,2,3-triazolo[4,5,b]pyridine.

3. The composition of claim 1, comprising 50 ppm to 500 ppm of the triazolylpyridine compound.

4. The composition of claim 1, wherein, This polishing composition does not contain per-compound oxidants.

5. The composition of claim 1, having a pH of 6 to 8.

6. The composition of claim 1, wherein, The cationic silica abrasive particles have an isoelectric point greater than 9.

7. The composition of claim 1, comprising less than 2% by weight of the cationic silica abrasive particles.

8. A method for chemically and mechanically polishing a substrate including a cobalt layer, the method comprising: (a) Contacting the substrate with a polishing composition, the polishing composition comprising: (i) Water-based liquid carriers; (ii) Cationic silica abrasive particles dispersed in the liquid carrier, wherein the cationic silica abrasive particles comprise colloidal silica particles having a permanent positive charge of at least 20 mV at a pH greater than 6. (iii) a triazole compound, wherein the triazole compound is a triazole pyridine compound selected from 1H-1,2,3-triazolo[4,5,b]pyridine and 1-acetyl-1H-1,2,3-triazolo[4,5,b]pyridine; and The polishing composition has a pH greater than 6; (b) moving the polishing composition relative to the substrate; and (c) Grind the substrate to remove a portion of the cobalt layer from the substrate and thereby polish the substrate.

9. The method of claim 8, wherein, The triazolylpyridine compound is 1H-1,2,3-triazolo[4,5,b]pyridine.

10. The method of claim 8, wherein, The polishing composition contains 50 ppm to 500 ppm of the triazolylpyridine compound.

11. The method of claim 8, wherein, This polishing composition does not contain per-compound oxidants.

12. The method of claim 8, wherein, The polishing composition has a pH of 6 to 8.

13. The method of claim 8, wherein, The cationic silica abrasive particles have an isoelectric point greater than 9.

14. The method of claim 8, comprising less than 2% by weight of the cationic silica abrasive particles.

15. The method of claim 8, wherein, The substrate further includes a dielectric layer, and wherein the polishing in (c) also removes a portion of the dielectric layer from the substrate.

16. The method of claim 15, wherein, The removal rate of the dielectric layer in (c) is greater than the removal rate of cobalt in (c).

17. The method of claim 16, wherein, The dielectric layer is tetraethyl orthosilicate (TEOS).

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