Tungsten grinding and polishing composition with improved morphology

Abstract

The present invention provides a chemical mechanical polishing composition comprising: a) surface-modified colloidal silicon oxide particles comprising negatively charged groups on a surface thereof, where the surface-modified colloidal silicon oxide particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about-5 mV to about-35 mV at a pH of about 3, b) an iron compound, c) a stabilizer, d) a corrosion inhibitor, and e) a surfactant. And e) an aqueous carrier. The invention also provides a method suitable for polishing a substrate.

Description

[0001] This application is a divisional application of the Chinese invention patent application (invention title: tungsten polishing composition with improved morphology, application date: January 4, 2019; application number: 201980007660.3). Background Art

[0002] In the fabrication of integrated circuits and other electronic devices, multiple conductive, semiconductive, and dielectric material layers are deposited on or removed from a substrate surface. As material layers are sequentially deposited on and removed from a substrate, the uppermost surface of the substrate may become uneven and require planarization. Planarization of a surface or "polishing" of a surface is a process in which material is removed from the surface of a substrate to form a generally uniform and flat surface. Planarization can be used to remove undesirable topography and surface defects, such as rough surfaces, agglomerated materials, lattice damage, scratches, and contaminated layers or materials. Planarization can also be used to form features on a substrate by removing excess deposited material that is used to fill the features and provide a uniform surface for subsequent processing and metallization levels.

[0003] Compositions and methods for planarizing or polishing a substrate surface are well known in the art. Chemical mechanical planarization or chemical mechanical polishing (CMP) is a common technique for planarizing a substrate. CMP employs a chemical composition referred to as a CMP composition or more simply a polishing composition (also referred to as a polishing slurry) for selectively removing material from a substrate. Typically, the polishing composition is applied to a substrate by contacting the surface of the substrate with a polishing pad (e.g., a polishing cloth or a polishing disk) saturated with the polishing composition. Typically, the polishing of the substrate is further aided by the chemical activity of the polishing composition and / or the mechanical activity of an abrasive suspended in the polishing composition or incorporated into a polishing pad (e.g., a fixed abrasive polishing pad).

[0004] Substrates having tungsten features disposed between dielectric features include semiconductor substrates including tungsten "plugs" and "interconnect" structures provided between features of dielectric material. The dielectric material (e.g., silicon oxide) conforms to the underlying topography of the substrate, and thus, the surface of the dielectric material is typically characterized by an inhomogeneous combination of raised areas of dielectric material separated by trenches in the dielectric material. The substrate surface area including raised dielectric material and trenches is referred to as a pattern field of the substrate, for example, "pattern material," "pattern oxide," or "pattern dielectric."

[0005] To create tungsten "plugs" and "interconnect" structures, tungsten is applied to a surface containing a patterned structure made at least in part from a dielectric material. Due to the variation in the depth of the trenches, typically, an excess of tungsten needs to be deposited on top of the substrate to ensure that all trenches are completely filled. The excess tungsten is then removed by a CMP process to expose the underlying dielectric layer and produce a flat surface of tungsten disposed between the spaces of the dielectric material. Tungsten can be removed in a "polishing" step or a "buffing" step, where a suitable tungsten removal rate can be desirable, but where other performance requirements (such as morphological performance) are also important.

[0006] The special requirements of tungsten polishing slurries, which combine the need for removal of tungsten and other film types (e.g., dielectric oxide films such as silicon oxide), present significant challenges. The morphology and throughput requirements of advanced tungsten nodes require CMP slurries with a combination of improved morphology performance (e.g., lower oxide erosion), improved performance with extended overpolishing, and reduced localized erosion phenomena, such as edge-overerosion (EOE) in pattern arrays and erosion near isolated lines (sometimes referred to as fanging), without compromising film removal requirements. As the name implies, EOE or fanging refers to localized erosion near the edge of the patterned area.

[0007] However, known CMP slurries have many disadvantages, for example, slurries with film removal rate capabilities may suffer from excessive EOE, which can cause yield loss. Alternatively, many slurries that can achieve desirable morphological properties have low film removal rates, which increases processing time and reduces the production capacity of the equipment. In addition, morphological performance and defectivity have been identified as gaps in existing tungsten buffered slurries based on silica. Anionic systems can improve defectivity while providing improved colloidal stability for improved storage life. However, currently, the use of anionic silica is limited due to many factors, for example, due to pH limitations due to Al leaching, aluminum-doped silica has a limited operating formula space. Moreover, known slurries prepared using anionic particles (e.g., MPS (mercapto-propylsilane sulfonated colloidal silica)) are limited due to low film removal rates and poor pattern performance (e.g., high erosion or EOE).

[0008] Although the EOE phenomenon is known in various CMP applications, including CMP of silicon, copper, and tungsten, the phenomenon is not fully understood. U.S. Pat. No. 6,114,248 discloses the use of reduced amounts of colloidal and pyrolytic silicon oxides and increased alkaline chemistries to improve EOE in polysilicon polishing. In addition, it has been proposed that the EOE phenomenon in copper CMP can be addressed by changing the electrochemical properties of copper (see, e.g., G. Banerjee and RLRhoades (ECS Transactions, 2008, Vol. 13, pp. 1-19)). However, chemical-based solutions may not be suitable for the jagged edges in tungsten polishing applications because tungsten inherently has different electrochemical properties than copper and silicon. Others have suggested that EOE in tungsten CMP can be addressed by changing mechanical factors (e.g., using small particles of colloidal silica) or processing conditions (e.g., a two-step setup of high downforce followed by low downforce during polishing or reconfiguring the polishing assembly) (see, e.g., R. Vacassy and Z. Chen, “Edge OverErosion in Tungsten CMP,” 2006, https: / / www.researchgate.net / publication / 290577656; SH Shin et al., “Relative Motion and Asymmetry Effect Analyses in Tungsten CMP Process,” http: / / www.planarization-cmp.org / contents / ICPT / PacRim2005 / S5-2.pdf).

[0009] However, changing process parameters is typically undesirable due to the complex operations involved, the possible reduction in throughput caused by increased polishing time, and / or the resulting lack of uniform polishing characteristics (which can adversely affect device yield). In addition, applicants have discovered that tungsten polishing slurries formulated with small colloidal silica result in a high propensity for EOE phenomena in tungsten polishing applications.

[0010] Therefore, there remains a need for compositions and methods for chemical mechanical polishing of substrates that provide useful removal rates while also providing improved planarization efficiency. The present invention provides such polishing compositions and methods. These and other advantages of the present invention and other features of the present invention will be apparent from the description of the present invention provided herein. Summary of the invention

[0011] The present invention provides a chemical mechanical polishing composition comprising: (a) surface-modified colloidal silica particles, the surface of which comprises negatively charged groups, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3, (b) an iron compound, (c) a stabilizer, (d) a corrosion inhibitor, and (e) an aqueous carrier.

[0012] The present invention also provides a method for chemically mechanically polishing a substrate, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition, which comprises (a) surface-modified colloidal silica, the surface of the particles comprising negatively charged groups, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3, (b) an iron compound, (c) a stabilizer, (d) a corrosion inhibitor, and (e) an aqueous carrier; (iv) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to grind at least a portion of the surface of the substrate, thereby polishing the substrate.

[0013] Specifically, the present invention includes:

[0014] 1. A chemical mechanical polishing composition comprising:

[0015] (a) surface-modified colloidal silica particles comprising negatively charged groups on the surface of the particles, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3,

[0016] (b) iron compounds,

[0017] (c) stabilizers,

[0018] (d) corrosion inhibitors, and

[0019] (e) Aqueous vehicle.

[0020] 2. The polishing composition according to item 1, wherein the negatively charged groups on the surface of the surface-modified colloidal silica particles comprise sulfonate groups, carboxylate groups, phosphonate groups, or a combination thereof.

[0021] 3. The polishing composition according to item 1, wherein the surface-modified colloidal silica particles have a particle size of about 90 nm to about 200 nm.

[0022] 4. The polishing composition according to item 3, wherein the surface-modified colloidal silica particles have a particle size of about 120 nm to about 180 nm.

[0023] 5. The polishing composition according to item 1, wherein the pH of the polishing composition is about 1.5 to about 4.

[0024] 6. The polishing composition according to item 5, wherein the pH of the polishing composition is about 2 to about 3.5.

[0025] 7. The polishing composition according to item 1, wherein the surface-modified colloidal silica particles are present in the polishing composition at a concentration of about 1.5 wt. % to about 3.5 wt. %.

[0026] 8. The polishing composition according to item 7, wherein the surface-modified colloidal silica particles are present in the polishing composition at a concentration of about 2 wt.% to about 3 wt.%.

[0027] 9. The polishing composition according to item 1, wherein the iron compound comprises iron nitrate or a hydrate thereof.

[0028] 10. The polishing composition according to item 1, wherein the stabilizer comprises phosphoric acid, o-phosphoethanolamine, alendronic acid, acetic acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, glutaconic acid, muconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, or a combination thereof.

[0029] 11. The polishing composition according to item 10, wherein the stabilizer comprises malonic acid.

[0030] 12. The polishing composition according to item 10, wherein the stabilizer is present in the polishing composition at a concentration of about 0.0001 wt.% to about 0.01 wt.%.

[0031] 13. The polishing composition according to item 1, wherein the corrosion inhibitor comprises glycine, alanine, lysine, arginine, histidine, or a combination thereof.

[0032] 14. The polishing composition according to item 13, wherein the corrosion inhibitor comprises alanine, glycine, lysine or arginine.

[0033] 15. The polishing composition according to item 14, wherein the corrosion inhibitor comprises glycine.

[0034] 16. The polishing composition according to item 13, wherein the corrosion inhibitor is present in the polishing composition at a concentration of about 0.005 wt.% to about 1 wt.%.

[0035] 17. The polishing composition according to item 16, wherein the corrosion inhibitor is present in the polishing composition at a concentration of about 0.1 wt.% to about 0.5 wt.%.

[0036] 18. A method for chemical mechanical polishing of a substrate, comprising:

[0037] (i) providing a substrate;

[0038] (ii) providing a polishing pad;

[0039] (iii) providing a chemical mechanical polishing composition comprising:

[0040] (a) surface-modified colloidal silica particles comprising negatively charged groups on the surface of the particles, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3,

[0041] (b) iron compounds,

[0042] (c) stabilizers,

[0043] (d) corrosion inhibitors, and

[0044] (e) an aqueous carrier;

[0045] (iv) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and

[0046] (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the surface of the substrate, thereby polishing the substrate.

[0047] 19. The method according to item 18, wherein the negatively charged groups on the surface of the surface-modified colloidal silica particles comprise sulfonate groups, carboxylate groups, phosphonate groups or a combination thereof.

[0048] 20. The method according to item 18, wherein the surface-modified colloidal silica particles have a particle size of about 90 nm to about 200 nm.

[0049] 21. The method according to item 20, wherein the surface-modified colloidal silica particles have a particle size of about 120 nm to about 180 nm.

[0050] 22. The method according to item 18, wherein the pH of the polishing composition is about 1.5 to about 4.

[0051] 23. The polishing composition according to item 22, wherein the pH of the polishing composition is about 2 to about 3.5.

[0052] 24. The method according to item 18, wherein the surface-modified colloidal silica particles are present in the polishing composition at a concentration of about 1.5 wt.% to about 3.5 wt.%.

[0053] 25. The method according to item 24, wherein the surface-modified colloidal silica particles are present in the polishing composition at a concentration of about 2 wt.% to about 3 wt.%.

[0054] 26. The method according to item 18, wherein the iron compound comprises ferric nitrate or a hydrate thereof.

[0055] 27. The method according to item 18, wherein the stabilizer comprises phosphoric acid, o-phosphoethanolamine, alendronic acid, acetic acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, glutaconic acid, muconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, or a combination thereof.

[0056] 28. The method according to item 27, wherein the stabilizer comprises malonic acid.

[0057] 29. The method according to item 27, wherein the stabilizer is present in the polishing composition at a concentration of about 0.0001 wt.% to about 0.01 wt.%.

[0058] 30. The method according to item 18, wherein the corrosion inhibitor comprises glycine, alanine, lysine, arginine, histidine, or a combination thereof.

[0059] 31. The method according to item 30, wherein the corrosion inhibitor comprises alanine, glycine, lysine or arginine.

[0060] 32. The method according to item 31, wherein the corrosion inhibitor comprises glycine.

[0061] 33. The method according to item 30, wherein the corrosion inhibitor is present in the polishing composition at a concentration of about 0.005 wt.% to about 1 wt.%.

[0062] 34. The method according to item 33, wherein the corrosion inhibitor is present in the polishing composition at a concentration of about 0.1 wt.% to about 0.5 wt.%.

[0063] 35. The method according to item 18, wherein the substrate comprises a tungsten layer on a surface of the substrate and a silicon oxide layer on the surface of the substrate, and wherein at least a portion of the tungsten layer and at least a portion of the silicon oxide layer are ground to polish the substrate.

[0064] 36. A method according to item 35, wherein the grinding of at least a portion of the tungsten layer provides a tungsten removal rate, wherein the grinding of at least a portion of the silicon oxide layer provides a silicon oxide removal rate, and wherein the ratio of the tungsten removal rate to the silicon oxide removal rate is about 0.5:1 to about 2.75:1. DETAILED DESCRIPTION

[0065] The present invention provides a chemical mechanical polishing composition comprising: (a) surface-modified colloidal silica particles, the surface of which comprises negatively charged groups, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3, (b) an iron compound, (c) a stabilizer, (d) a corrosion inhibitor, and (e) an aqueous carrier.

[0066] Without wishing to be bound by any particular theory, applicants have discovered that polishing compositions comprising surface-modified particles described herein having a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3 exhibit improved topographical properties, including lower erosion and jaggedness.

[0067] The polishing composition comprises an abrasive comprising, consisting essentially of, or consisting of surface-modified (e.g., surface-functionalized) colloidal silica particles, wherein the colloidal silica particles are surface-modified such that the modified colloidal silica particles have negatively charged groups on the particle surface. Thus, the surface-modified colloidal silica particles have a negative charge. The negative charge is provided by modifying the silica abrasive with negatively charged groups that are covalently attached to the silica surface.

[0068] As used herein, the term "negative charge" refers to a negative charge on the surface-modified colloidal silica particles that is not easily reversed (i.e., irreversible or permanent), such as by washing, dilution, or filtration. The negative charge can be, for example, the result of covalent bonding of anionic species (e.g., negatively charged groups) to the colloidal silica. In contrast, a reversible negative charge (non-permanent negative charge) can be, for example, the result of electrostatic interactions between anionic species and colloidal silica, such as an anionic surfactant or anionic polymer that can, for example, be electrostatically bound to the surface of the silica particles.

[0069] The negatively charged group can be any suitable group that can affect the negative charge on the surface of the colloidal silica particles. For example, the negatively charged group can be an organic acid (e.g., a carboxylic acid, a sulfonic acid, and / or a phosphonic acid). In a preferred embodiment, the negatively charged group comprises a sulfonate group, a carboxylate group, a phosphonate group, or a combination thereof.

[0070] In a preferred embodiment, the sulfonate group is a silane containing one or more sulfonate groups or sulfate groups. The sulfonate group may also be a sulfonate or sulfate precursor, which may then be converted to a sulfonate or sulfate by, for example, oxidation. Suitable sulfonate groups include, for example, 3-(trihydroxysilyl)-1-propanesulfonic acid, triethoxysilylpropyl(polyethyleneoxy)propylsulfonic acid, or a salt thereof (e.g., potassium salt). Suitable sulfonate precursors include, for example, 3-mercaptopropyltrimethoxysilane, (mercaptomethyl)methyldiethoxysilane, and 3-mercaptopropylmethyldimethoxysilane.

[0071] Suitable carboxylate groups or carboxylate precursors include, for example, (3-triethoxysilyl)propyl succinic anhydride, carboxyethylsilanetriol or a salt thereof, and N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid or a salt thereof. The carboxylate precursor is converted (e.g., oxidized) to the carboxylate group or is converted in situ (e.g., during work-up) to the carboxylate group.

[0072] Suitable phosphonate groups include, for example, 3-(trihydroxysilyl)propylmethylphosphonic acid and its salts.

[0073] The negatively charged group may also be a silane coupling agent. Silane coupling agents may be used to modify the surface of silicon oxide to provide the surface-modified colloidal silica particles of the present invention. Examples of silane coupling agents incorporating negatively charged groups or precursors for negatively charged groups have been described by Gelest, Inc. (Silane Coupling Agents, Copyright 2014, Gelest, Inc., Morrisville, PA) and are included herein by reference.

[0074] Surface-modified colloidal silica particles can be prepared using any suitable method. Typically, the colloidal silica particles contain no or substantially no negatively charged groups before the surface modification using negatively charged groups (i.e., unmodified colloidal silica particles). The unmodified colloidal silica particles can be any suitable colloidal silica particles and are typically "wet process" colloidal silica particles. As used herein, "wet process" silica refers to silica prepared by precipitation, condensation-polymerization or similar processes (as opposed to, for example, fumed or pyrogenic silica). In a preferred embodiment, the colloidal silica particles are prepared by condensation-polymerization of Si(OH)4. The precursor Si(OH)4 can be obtained by, for example, hydrolysis of high purity alkoxysilanes (e.g., tetramethyl orthosilicate (TMOS)). Such colloidal silica particles can be obtained as various commercially available products, such as Fuso Chemical Co.'s "PL" colloidal silica products, such as PL-5 and PL-7. In another preferred embodiment, the silica particles are prepared from sodium silicate. Sodium silicate useful in the present invention can be obtained, for example, from Nalco. Examples of commercially available colloidal silica derived from sodium silicate include Nalco 1050, 2327 and 2329 products and other similar products obtained from DuPont, Bayer, Applied Research, Nissan Chemical and Clariant.

[0075] The colloidal silica particles can be surface modified using any suitable method. In an embodiment, the surface treatment for providing negatively charged groups to the surface of the colloidal silica particles is by reacting with the silane surface of the colloidal silica. For example, in the case where a sulfonic acid (e.g., a sulfonate group) (which is an organic acid) is covalently attached to the colloidal silica, the connection can be implemented according to the method of "Sulfonic acid-functionalized silica through quantitative oxidation of thiol groups" by Cano-Serrano et al., Chem. Commun., 2003 (2): 246-247 (2003). Specifically, colloidal silica having a sulfonic acid covalently attached to its surface is obtained by coupling a silane coupling agent having a thiol group (e.g., (3-mercaptopropyl) trimethoxysilane) with the colloidal silica and then oxidizing the thiol group using hydrogen peroxide. Alternatively, for example, in the case where a carboxylic acid (i.e., a carboxylate group) is covalently linked to colloidal silica, the linking can be performed according to the method of "Novel silane coupling agents containing aphotolabile2-nitrobenzyl ester for introduction of a carboxy group" by Yamaguchi et al., Chemistry Letters, 3:228-229 (2000). Specifically, colloidal silica having a carboxylic acid covalently linked to its surface is obtained by coupling a silane coupling agent containing a photosensitive 2-nitrovinyl ester to colloidal silica and then irradiating it with light.

[0076] The surface modified colloidal silica particles have a particle size of about 90 nm to about 350 nm. As used herein, particle size refers to the diameter of the smallest sphere surrounding the particle. The particle size of the colloidal silica particles can be measured using any suitable technique (e.g., light scattering technique). Suitable particle size measuring instruments can be obtained from (e.g.) Malvern Instruments (Malvern, UK). The particle size can be measured using any suitable technique known to those skilled in the art, for example, laser diffraction techniques, differential centrifugal sedimentation (DCS) using, for example, a disc centrifuge (e.g., DC24000UHR CPS disc centrifuge) from CPS Instruments (Prairieville, La.).

[0077] Thus, the particle size of the surface-modified colloidal silica particles can be about 90 nm or greater, for example, about 95 nm or greater, about 100 nm or greater, about 105 nm or greater, about 110 nm or greater, about 115 nm or greater, about 120 nm or greater, about 125 nm or greater, about 130 nm or greater, about 135 nm or greater, about 140 nm or greater, about 145 nm or greater, about 150 nm or greater, about 155 nm or greater, about 160 nm or greater, about 165 nm or greater, about 170 nm or greater, about 175 nm or greater, about 180 nm or greater, about 185 nm or greater, about 190 nm or greater, about 195 nm or greater, or about 200 nm or greater. Alternatively, or in addition, the colloidal silica particles may have a particle size of about 350 nm or less, e.g., about 345 nm or less, about 340 nm or less, about 335 nm or less, about 330 nm or less, about 325 nm or less, about 320 nm or less, about 315 nm or less, about 310 nm or less, about 305 nm or less, about 300 nm or less, about 295 nm or less, about 290 nm or less, about 285 nm or less. The colloidal silica particles may have a particle size of about 280 nm or less, about 275 nm or less, about 270 nm or less, about 265 nm or less, about 260 nm or less, about 255 nm or less, about 250 nm or less, about 245 nm or less, about 240 nm or less, about 235 nm or less, about 230 nm or less, about 225 nm or less, about 220 nm or less, about 215 nm or less, about 210 nm or less, or about 205 nm or less. Thus, the colloidal silica particles may have a particle size defined by any two of the above endpoints. For example, the colloidal silica particles may have a particle size of about 90 nm to about 350 nm, about 95 nm to about 345 nm, about 90 nm to about 340 nm, or about 85 nm to about 335 nm.

[0078] In an embodiment, the colloidal silica particles have a particle size of about 90 nm to about 200 nm.

[0079] In another embodiment, the colloidal silica particles have a particle size of about 120 nm to about 180 nm.

[0080] The surface-modified colloidal silica particles have a negative zeta potential at a pH of about 3, more specifically, a zeta potential of about -5 mV to about -35 mV (e.g., about -10 mV, about -15 mV, about -20 mV, about -25 mV, or about -30 mV). The zeta potential of a particle refers to the difference between the charge of the ions surrounding the particle and the charge of the bulk solution (e.g., the aqueous vehicle and any other components dissolved therein). Typically, the zeta potential depends on the pH of the aqueous medium (e.g., the aqueous vehicle). For a given polishing composition, the isoelectric point of the particle is defined as the pH at which the zeta potential is zero. As the pH increases or decreases away from the isoelectric point, the surface charge (and therefore the zeta potential) decreases or increases (to a negative or positive zeta potential value) accordingly. In addition, in the context of the present invention, the zeta potential is an indicator of the degree of surface modification of the colloidal silica particles, because, in the pH range of about 1 to about 4, a more negative zeta potential generally corresponds to a higher degree of surface modification.

[0081] Thus, any two of the above mentioned values ​​of zeta potential can be used to define a range. For example, the surface modified colloidal silica particles can have a zeta potential of about -5 mV to about -35 mV, about -10 mV to about -25 mV, or about -15 mV to about -20 mV at a pH of about 3. As a further example, the surface modified colloidal silica particles can have a zeta potential of about -5 mV, about -6 mV, about -7 mV, about -8 mV, about -9 mV, about -10 mV, about -11 mV, about -12 mV, about -13 mV, about -14 mV, about -15 mV, about -16 mV, about -17 mV, about -18 mV, about -19 mV, about -20 mV, about -21 mV, about -22 mV, about -23 mV, about -24 mV, about -25 mV, about -26 mV, about -27 mV, about -28 mV, about -29 mV, about -30 mV, about -31 mV, about -32 mV, about -33 mV, about -34 mV, or about -35 mV at a pH of about 3. Thus, the surface-modified colloidal silica particles have a suitable zeta potential in a suitable pH range. Typically, the pH of the polishing composition is about 1.5 to about 4 (e.g., a pH of about 1.6, about 1.7, about 1.8, about 1.9, about 2, about 2.1, about 2.2, about 2.3, about 2.4, about 2.5, about 2.6, about 2.7, about 2.8, about 2.9, about 3.0, about 3.1, about 3.2, about 3.3, about 3.4, about 3.5, about 3.6, about 3.7, about 3.8, or about 3.9). For example, the pH of the polishing composition can be about 1.6 to about 3.9, about 1.7 to about 3.8, about 1.8 to about 3.7, about 1.9 to about 3.6, or about 2.0 to about 3.5.

[0082] In some embodiments, the surface modified colloidal silica particles have a zeta potential of about -5 mV to about -25 mV in a pH range of about 2 to about 4.

[0083] In some embodiments, the surface modified colloidal silica particles have a zeta potential of about -10 mV to about -20 mV in a pH range of about 2 to about 4.

[0084] The zeta potential of the polishing composition can be measured by any suitable means, for example, using a commercially available instrument, such as DT-1202, an electroacoustic spectrometer available from Dispersion Technology, Inc. (Bedford Hills, NY). To measure the zeta potential on the DT-1202, it is preferred that the solution be measured at a solids concentration corresponding to the abrasive concentration used in chemical mechanical polishing (e.g., 2% solids).

[0085] The chemical mechanical polishing composition can include any suitable amount of surface-modified colloidal silica particles. If the composition includes too few surface-modified colloidal silica particles, the composition may not exhibit sufficient removal rates. Conversely, if the polishing composition includes too many surface-modified colloidal silica particles, the composition may exhibit undesirable polishing performance, may not be cost-effective, and / or may lack stability.

[0086] The surface-modified colloidal silica particles are suspended in an aqueous carrier of the polishing composition such that the surface-modified colloidal silica particles are desirably colloidally stable. As used herein, the term "colloidally stable" refers to a suspension of abrasive particles in an aqueous carrier (e.g., water) and refers to the retention of the suspension over time. In the context of the present invention, the abrasive particles (i.e., surface-modified colloidal silica particles) are considered to be colloidally stable if the difference between the particle concentration in the bottom 50 mL of the graduated cylinder ([B], expressed in g / mL) and the particle concentration in the top 50 mL of the graduated cylinder ([T], expressed in g / mL) when the abrasive particles are placed in a 100 mL graduated cylinder and allowed to stand for a period of 2 hours without agitation is divided by the initial concentration of particles in the abrasive composition ([C], expressed in g / mL) is less than or equal to 0.5 (i.e., {[B]-[T]} / [C]≤0.5). Desirably, the value of [B] - [T] / [C] is less than or equal to 0.3, and preferably less than or equal to 0.1.

[0087] Thus, the surface-modified colloidal silica particles are typically present in the polishing composition at a concentration of about 5 wt % or less, e.g., about 4.5 wt % or less, about 4 wt % or less, about 3.5 wt % or less, about 3 wt % or less, or about 2.5 wt % or less. Alternatively, or in addition, the surface-modified colloidal silica particles may be present in the polishing composition at a concentration of about 0.5 wt % or more, e.g., about 1 wt % or more, about 1.5 wt % or more, or about 2 wt % or more. Thus, the surface-modified colloidal silica particles may be present in the polishing composition at a concentration defined by any two of the above-mentioned endpoints. For example, the surface-modified colloidal silica particles may be present in the polishing composition at a concentration of about 0.5 wt % to about 5 wt %, e.g., about 1 wt % to about 4.5 wt %, about 1.5 wt % to about 4 wt %, about 2 wt % to about 3.5 wt %, or about 2.5 wt % to about 3 wt %.

[0088] In a preferred embodiment, the surface-modified colloidal silica particles are present in the polishing composition at a concentration of about 1.5 wt.% to about 3.5 wt.%.

[0089] The polishing composition of the present invention comprises an iron compound. Examples of iron-containing salts are described in U.S. Pat. Nos. 5,958,288 and 5,980,775, both of which are incorporated herein by reference. Suitable iron compounds (e.g., iron-containing salts) include, for example: ferric iron (iron III) or ferrous iron (iron II) compound salts, such as ferric nitrate, ferric sulfate; iron halides (including fluorides, chlorides, bromides, iodides, and perchlorates, perbromates, and periodates); or organic iron compounds, such as ferric acetate, ferric acetylacetonate, ferric citrate, ferric gluconate, ferric malonate, ferric oxalate, ferric phthalate, or ferric succinate.

[0090] In a preferred embodiment, the iron compound is ferric nitrate or a hydrate thereof (eg, ferric nitrate nonahydrate).

[0091] The polishing composition may contain any suitable amount of the iron compound. If the polishing composition contains too little iron compound, the composition may not exhibit sufficient removal rate. In contrast, if the polishing composition contains too much iron compound, the composition may exhibit undesirable polishing performance, may not be cost-effective, and / or may lack stability. Therefore, the iron compound is typically present in the polishing composition at a concentration of about 0.5 wt % or less, for example, about 0.1 wt % or less, or about 0.05 wt % or less. Alternatively, or in addition, the iron compound may be present in the polishing composition at a concentration of about 0.001 wt % or more, for example, about 0.005 wt % or more, or about 0.01 wt % or more. Therefore, the iron compound may be present in the polishing composition at a concentration defined by any two of the above endpoints (e.g., at a concentration of about 0.001 wt % to about 0.5 wt %, about 0.005 wt % to about 0.1 wt %, or about 0.01 wt % to about 0.05 wt %).

[0092] The polishing composition of the present invention comprises a stabilizer. Without wishing to be bound by any particular theory, the stabilizer helps control the amount of free metal cations in the composition, thereby attenuating the rate of the catalyst to optimize polishing performance, as described in U.S. Pat. Nos. 5,980,775 and 6,068,787, both of which are incorporated herein by reference.

[0093] In another embodiment of the present invention, the iron compound can be fixed on the surface of the abrasive. For example, the iron compound can be composed of an iron salt and a stabilizer attached to the surface of the abrasive.

[0094] In embodiments, the stabilizer comprises phosphoric acid, o-phosphoethanolamine, phosphonic acid, alendronic acid, acetic acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, oxalic acid, maleic acid, glutaconic acid, muconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, or a combination thereof.

[0095] In a preferred embodiment, the stabilizer comprises malonic acid.

[0096] The polishing composition may include any suitable amount of stabilizer. If the composition includes too little stabilizer, the composition may not exhibit sufficient stability. In contrast, if the polishing composition includes too much stabilizer, the composition may exhibit undesirable polishing performance, may not be cost-effective, and / or may become unstable. Therefore, the stabilizer is typically present in the polishing composition at a concentration of about 1 wt % or less, for example, about 0.5 wt % or less, about 0.1 wt % or less, about 0.05 wt % or less, or about 0.01 wt % or less. Alternatively, or in addition, the stabilizer may be present in the polishing composition at a concentration of about 0.0001 wt % or more, for example, about 0.0005 wt % or more, about 0.001 wt % or more, or about 0.005 wt % or more. Therefore, the stabilizer may be present in the polishing composition at a concentration defined by any two of the above-mentioned endpoints. For example, the stabilizer can be present in the polishing composition at a concentration of about 0.0001 wt.% to about 1 wt.%, e.g., about 0.0005 wt.% to about 0.5 wt.%, about 0.001 wt.% to about 0.1 wt.%, or about 0.005 wt.% to about 0.05 wt.%.

[0097] In a preferred embodiment, the polishing composition comprises a stabilizer at a concentration of about 0.0001 wt.% to about 0.01 wt.%.

[0098] The polishing composition of the present invention includes a corrosion inhibitor (e.g., a film former). As used herein, a corrosion inhibitor is a compound or a mixture of compounds that promotes the formation of a passivation layer (i.e., a dissolution inhibition layer) on at least a portion of the polished surface. Without wishing to be bound by any particular theory, the corrosion inhibitor inhibits the conversion of solid metals into soluble metal compounds while allowing effective removal of solid metals via CMP operations. For example, the types of compounds used as corrosion inhibitors for tungsten etching include compounds having nitrogen-containing functional groups, such as nitrogen-containing heterocycles, alkylammonium ions, aminoalkyl groups, and amino acids. Useful aminoalkyl corrosion inhibitors include, for example, hexylamine, tetramethyl-p-phenylenediamine, octylamine, diethylenetriamine, dibutylbenzylamine, aminopropylsilanol, aminopropylsiloxane, dodecylamine, mixtures thereof, and synthetic and natural amino acids, including, for example, arginine, lysine, tyrosine, glutamine, glutamic acid, cystine, and glycine (aminoacetic acid). The corrosion inhibitor may be any suitable corrosion inhibitor for any component of the substrate. Preferably, the corrosion inhibitor is a tungsten corrosion inhibitor or a silicon oxide corrosion inhibitor.

[0099] In an embodiment, the corrosion inhibitor comprises glycine, alanine, lysine, arginine, histidine, or a combination thereof.

[0100] In a preferred embodiment, the corrosion inhibitor comprises alanine, glycine, lysine or arginine. The corrosion inhibitor can be used alone or in combination.

[0101] In another preferred embodiment, the corrosion inhibitor comprises glycine.

[0102] The polishing composition may include any suitable amount of the corrosion inhibitor, if present. If the polishing composition includes too little corrosion inhibitor, the polishing composition may not exhibit sufficient polishing performance. In contrast, if the polishing composition includes too much corrosion inhibitor, the composition may exhibit undesirable polishing performance, may not be cost-effective, and / or may lack stability. Typically, when present, the polishing composition includes about 0.005 wt % to about 1 wt % (e.g., about 0.01 wt % to about 0.5 wt %, or about 0.02 wt % to about 0.2 wt %) of the corrosion inhibitor. In a preferred embodiment, when present, the polishing composition includes about 0.1 wt % to about 0.5 wt % of the corrosion inhibitor.

[0103] The polishing composition includes an aqueous carrier. The aqueous carrier includes water (e.g., deionized water) and may contain one or more organic solvents that are miscible with water. Examples of organic solvents that can be used include alcohols such as acryl alcohol, isopropanol, ethanol, 1-propanol, methanol, 1-hexanol, etc.; aldehydes such as acetylaldehyde, etc.; ketones such as acetone, diacetone alcohol, methyl ethyl ketone, etc.; esters such as ethyl formate, propyl formate, ethyl acetate, methyl acetate, methyl lactate, butyl lactate, ethyl lactate, etc.; ethers including sulfoxides such as dimethyl sulfoxide (DMSO), tetrahydrofuran, dimethicone, etc. alkane, diethylene glycol dimethyl ether, etc.; amides, such as N,N-dimethylformamide, dimethylimidazolidinone, N-methylpyrrolidone, etc.; polyols and their derivatives, such as ethylene glycol, glycerol, diethylene glycol, diethylene glycol monomethyl ether, etc.; and nitrogen-containing organic compounds, such as acetonitrile, pentylamine, isopropylamine, imidazole, dimethylamine, etc. Preferably, the aqueous carrier is only water, that is, no organic solvent is present.

[0104] Desirably, the polishing composition of the present invention is stable during preparation, long-term storage, transportation, and use. A stable slurry is one that does not excessively separate or settle during storage (e.g., due to settling of suspended abrasive particles), does not exhibit excessive particle size growth during storage, and does not exhibit excessive particle size growth during use (which would increase the extent of defects (especially scratches) present at the surface of the treated substrate).

[0105] The polishing composition optionally further comprises one or more other additional components (i.e., additives). For example, depending on the desired polishing application, the polishing composition of the present invention may comprise one or more additives to improve or enhance polishing performance. Desirably, the additives are compatible with the other components of the polishing composition. Illustrative additional components include conditioners, scale inhibitors, dispersants, oxidants, pH adjusting compounds (e.g., acids or bases), and pH buffering compounds. The polishing composition may comprise surfactants and / or rheology control agents, including viscosity enhancers and coagulants (e.g., polymeric rheology control agents, such as urethane polymers), dispersants, biocides (e.g., KATHON TM LX), etc. Suitable surfactants include, for example, cationic surfactants, anionic surfactants, anionic polyelectrolytes, nonionic surfactants, amphoteric surfactants, fluorinated surfactants, and mixtures thereof.

[0106] The polishing composition can be prepared by any suitable technique, many of which are known to those skilled in the art. The polishing composition can be prepared in a batch or continuous process. In general, the polishing composition can be prepared by combining the components described herein in any order. As used herein, the term "component" includes individual ingredients (e.g., surface-modified colloidal silica particles, iron compounds, stabilizers, corrosion inhibitors, etc.) as well as any combination of the ingredients.

[0107] For example, an iron compound, a stabilizer, and a corrosion inhibitor can be added to an aqueous carrier (e.g., water) at a desired concentration. The pH can then be adjusted (as desired), and the surface-modified colloidal silica particles can be added to the mixture at a desired concentration to form a polishing composition. The polishing composition can be prepared prior to use, wherein one or more components are added to the polishing composition just prior to use (e.g., within about 1 minute prior to use, or within about 1 hour prior to use, or within about 7 days prior to use). The polishing composition can also be prepared by mixing the components at the substrate surface during a polishing operation.

[0108] The polishing composition can also be provided as a concentrate that is intended for dilution with an appropriate amount of an aqueous vehicle, particularly water, prior to use. In such an embodiment, the polishing composition concentrate can contain surface-modified colloidal silica particles, an iron compound, a stabilizer, and a corrosion inhibitor and an aqueous vehicle in amounts such that when the concentrate is diluted with an appropriate amount of water, the components of the polishing composition will be present in the polishing composition at concentrations within the appropriate ranges described above for each component. In addition, as will be appreciated by one of ordinary skill in the art, the concentrate can 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.

[0109] Although the polishing composition can be prepared long before or even shortly before use, the polishing composition can also be prepared by mixing the components of the polishing composition at or near the point of use. As used herein, the term "point of use" refers to the site at which the polishing composition is applied to a substrate surface (e.g., a polishing pad or the substrate surface itself). When point-of-use mixing is intended to produce the polishing composition, the components of the polishing composition are stored separately in two or more storage devices.

[0110] The present invention further provides methods of chemically mechanically polishing substrates using the inventive CMP compositions described herein.

[0111] In an embodiment, the present invention provides a method for chemically mechanically polishing a substrate, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition comprising (a) surface-modified colloidal silica comprising negatively charged groups on the surface of the particles, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3, (b) an iron compound, (c) a stabilizer, (d) a corrosion inhibitor, and (e) an aqueous carrier; (iv) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the surface of the substrate, thereby polishing the substrate.

[0112] The polishing method of the present invention can be used to polish any suitable substrate. The polishing composition is particularly useful for polishing a substrate comprising a tungsten layer and a silicon oxide layer. Suitable substrates include, but are not limited to, flat panel displays, integrated circuits, memory or hard disks, metals, semiconductors, interlayer dielectric (ILD) devices, microelectromechanical systems (MEMS), 3D NAND devices, ferroelectrics, and magnetic heads. The polishing composition is particularly suitable for planarizing or polishing substrates that have undergone shallow trench isolation (STI) processing. Desirably, the substrate includes a surface containing a dielectric (e.g., containing silicon oxide), especially a surface having a patterned dielectric material area including raised dielectric areas separated by trench areas of dielectric material. The substrate may further include at least one other layer, such as an insulating layer. The insulating layer may be a metal oxide, a porous metal oxide, a glass, an organic polymer, a fluorinated organic polymer, or any other suitable high or low-κ insulating layer. The insulating layer may include, consist essentially of, or consist of silicon oxide, silicon nitride, or a combination thereof. The silicon oxide layer may comprise, consist essentially of, or consist of any suitable silicon oxide, many of which are known in the art. For example, the silicon oxide layer may comprise tetraethoxysilane (TEOS), high density plasma (HDP) oxide, borophosphosilicate glass (BPSG), high aspect ratio process (HARP) oxide, spin-on dielectric (SOD) oxide, chemical vapor deposition (CVD) oxide, plasma enhanced tetraethyl orthosilicate (PETEOS), thermal oxide, or undoped silicate glass. The substrate may further comprise a metal layer. The metal may comprise, consist essentially of, or consist of any suitable metal, many of which are known in the art, such as copper, tantalum, tungsten, titanium, platinum, ruthenium, iridium, aluminum, nickel, or combinations thereof.

[0113] In a preferred embodiment, the substrate comprises a tungsten layer and a silicon oxide layer on a surface of the substrate.

[0114] In another preferred embodiment, the substrate includes tungsten plugs and interconnect structures.

[0115] The polishing composition of the present invention advantageously exhibits removal rate selectivity, making the polishing composition suitable for buff polishing applications. In addition, the polishing composition of the present invention advantageously exhibits improved polishing performance (e.g., improved defectivity, reduced corrosion, and reduced EOE) that is well suited for producing high-quality devices from processed substrates.

[0116] In an embodiment of the present invention, the ratio of the removal rate of the tungsten layer to the removal rate of the silicon oxide layer is from about 0.5:1 to about 2.75:1, for example, from about 1:1, about 2.5:1, about 1.25:1 to about 2.25:1, about 1.5:1 to about 2:1, about 1.75:1 to about 1.5, about 2:1 to about 1.25:1, about 2.25:1 to about 1:1, or about 2.5:1 to about 0.5:1.

[0117] The polishing performance of the compositions of the present invention may be evaluated using any suitable substrate or method. One type of substrate suitable for evaluating polishing performance is a substrate comprising a line and space (L&S) pattern, wherein the surface comprises a line field and a space. The line field or patterned field comprises an array of lines of metal and oxide and may include isolated metal lines located in an otherwise continuous oxide field. The line field is distributed in a field (space) of continuous dielectric material. The line array comprises metal and oxide lines (e.g., lines of tungsten and silicon oxide) and may have any density or size, for example, alternating 1 μm wide metal lines and 1 μm wide oxide lines (i.e., a 50% 1 μm array), or alternating lines of different sizes or densities, for example, 1 μm wide metal lines and 3 μm wide oxide lines (i.e., a 25% 1×3 μm array). The isolated metal lines are typically associated with the line array and are located in the oxide field at a distance from the array and typically have the same size (width) as the metal lines in the array. For example, for one side of a 1×1 μm array of lines, there may be two 1 μm isolated metal lines in an otherwise continuous oxide field and separated from the array and from each other by >100 μm. In comparison, the size of a continuous dielectric material field may typically be larger and have a surface of continuous dielectric material (e.g., silicon oxide, such as TEOS). An exemplary continuous dielectric material field (or "space") may be a 100×100 μm area.

[0118] To evaluate the pattern performance of such L&S substrates after polishing, the absolute oxide loss (material removed) occurring at a continuous dielectric field is measured, for example, by optical methods using commercially available equipment (F5X tool, supplied by KLA Tencor, Milpitas, CA). The continuous dielectric field is used as a reference for relative pattern measurements in an array. For example, a line array consisting of alternating tungsten metal and TEOS oxide lines can be measured by profilometry or atomic force microscopy (AFM) for the continuous field oxide. Erosion is characterized as the difference in the relative height of the oxide (e.g., 1 μm TEOS lines) in the line array compared to the continuous field oxide. Positive erosion values ​​are interpreted as the relative recessing of the oxide lines compared to the continuous field oxide. Metal dishing typically refers to the relative height of the metal lines in the line array compared to the oxide lines. For example, in a 50% 1×1 μm line array, The value of the depression is explained by the relative Recessed. In this case, the sum of erosion and recessed provides the total step height from the recessed (recessed tungsten) to the field oxide. The total oxide or metal loss in the array can be determined by combining the recess and erosion values ​​with the absolute oxide loss value measured for the continuous field.

[0119] Other erosion phenomena associated with the pattern are localized areas of erosion, for example, increased erosion associated with the edge of an array of lines, or increased erosion in areas close to isolated lines. For example, for a 1 μm isolated line in an oxide field, localized erosion may be observed as an increase in line width to >1 μm. Erosion may be described in terms of increased line width, or in terms of an increase in line width to a specific depth relative to a reference field, or a combination of these two characteristics.

[0120] The chemical mechanical polishing composition and method of the present invention are particularly suitable for use in conjunction with a chemical mechanical polishing apparatus. Typically, the apparatus includes: a platen, which, when used, is in motion and has a velocity generated by orbital, linear or circular motion; a polishing pad, which is in contact with the platen and moves with the platen when in motion; and a carrier, which holds a substrate to be polished by contacting the surface of the polishing pad and moving the substrate relative to the surface of the polishing pad. The 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 polish the substrate by abrading at least a portion of the substrate.

[0121] The chemical mechanical polishing composition can be used to polish the substrate using any suitable polishing pad (e.g., polishing surface). Suitable polishing pads include, for example, woven and non-woven polishing pads. Moreover, suitable polishing pads may include any suitable polymers having various densities, hardnesses, thicknesses, compressibility, compression resilience, and compression modulus. Suitable polymers include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbons, polycarbonates, polyesters, polyacrylates, polyethers, polyethylene, polyamides, polyurethanes, polystyrene, polypropylene, co-formed products thereof, and mixtures thereof. Soft polyurethane polishing pads are particularly suitable for use in conjunction with the polishing method of the present invention. Typical pads include, but are not limited to, SURFIN TM 000, SURFIN TM SSW1, SPM3100 (Eminess Technologies), POLITEX TM (Dow Chemical Company) and POLYPAS TM 27 (Fujibo), NEXPLANAR commercially available from Cabot Microelectronics TM E6088 and EPIC TMD100 pad. A particularly preferred polishing pad is a rigid microporous polyurethane pad commercially available from Dow Chemical (IC1010 TM ).

[0122] Desirably, the chemical mechanical polishing apparatus further comprises an in-situ polishing endpoint detection system, many of which are known in the art. Techniques for inspecting and monitoring the polishing process by analyzing light or other radiation reflected from the surface of the substrate being polished are known in the art. Such methods are described, for example, in U.S. Patents 5,196,353, 5,433,651, 5,609,511, 5,643,046, 5,658,183, 5,730,642, 5,838,447, 5,872,633, 5,893,796, 5,949,927, and 5,964,643. Desirably, inspection or monitoring of the progress of the polishing process for the substrate being polished enables determination of the polishing endpoint, i.e., determination of when to terminate the polishing process for a particular substrate.

[0123] Implementation

[0124] (1) In embodiment (1), a chemical mechanical polishing composition is presented, comprising: (a) surface-modified colloidal silica particles comprising negatively charged groups on the surface of the particles, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3, (b) an iron compound, (c) a stabilizer, (d) a corrosion inhibitor, and (e) an aqueous carrier.

[0125] (2) In embodiment (2), the polishing composition of embodiment (1) is presented, wherein the negatively charged groups on the surface of the surface-modified colloidal silica particles comprise sulfonate groups, carboxylate groups, phosphonate groups, or a combination thereof.

[0126] (3) In embodiment (3), the polishing composition of any one of embodiments (1) or (2) is presented, wherein the surface-modified colloidal silica particles have a particle size of about 90 nm to about 200 nm.

[0127] (4) In embodiment (4), the polishing composition of embodiment (3) is presented, wherein the surface-modified colloidal silica particles have a particle size of about 120 nm to about 180 nm.

[0128] (5) In embodiment (5), the polishing composition of any one of embodiments (1) to (4) is presented, wherein the pH of the polishing composition is from about 1.5 to about 4.

[0129] (6) In embodiment (6), the polishing composition of embodiment (5) is presented, wherein the pH of the polishing composition is from about 2 to about 3.5.

[0130] (7) In embodiment (7), the polishing composition of any one of embodiments (1)-(6) is presented, wherein the surface-modified colloidal silica particles are present in the polishing composition at a concentration of about 1.5 wt. % to about 3.5 wt. %.

[0131] (8) In embodiment (8), the polishing composition of embodiment (7) is presented, wherein the surface-modified colloidal silica particles are present in the polishing composition at a concentration of about 2 wt. % to about 3 wt. %.

[0132] (9) In embodiment (9), the polishing composition of any one of embodiments (1) to (8) is presented, wherein the iron compound comprises iron nitrate or a hydrate thereof.

[0133] (10) In embodiment (10), a polishing composition of any one of embodiments (1) to (9) is presented, wherein the stabilizer comprises phosphoric acid, o-phosphoethanolamine, alendronic acid, acetic acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, glutaconic acid, muconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, or a combination thereof.

[0134] (11) In embodiment (11), the polishing composition of embodiment (10) is presented, wherein the stabilizer comprises malonic acid.

[0135] (12) In embodiment (12), the polishing composition of embodiment (10) or (11) is presented, wherein the stabilizer is present in the polishing composition at a concentration of about 0.0001 wt. % to about 0.01 wt. %.

[0136] (13) In embodiment (13), the polishing composition of any one of embodiments (1) to (12) is presented, wherein the corrosion inhibitor comprises glycine, alanine, lysine, arginine, histidine, or a combination thereof.

[0137] (14) In embodiment (14), the polishing composition of embodiment (13) is presented, wherein the corrosion inhibitor comprises alanine, glycine, lysine and arginine.

[0138] (15) In embodiment (15), the polishing composition of embodiment (14) is presented, wherein the corrosion inhibitor comprises glycine.

[0139] (16) In embodiment (16), the polishing composition of any one of embodiments (1)-(15) is presented, wherein the corrosion inhibitor is present in the polishing composition at a concentration of about 0.005 wt. % to about 1 wt. %.

[0140] (17) In embodiment (17), the polishing composition of embodiment (16) is presented, wherein the corrosion inhibitor is present in the polishing composition at a concentration of about 0.1 wt. % to about 0.5 wt. %.

[0141] (18) In embodiment (18), a method for chemical mechanical polishing a substrate is presented, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition, which comprises: (a) surface-modified colloidal silica, the surface of the particles comprising negatively charged groups, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3, (b) an iron compound, (c) a stabilizer, (d) a corrosion inhibitor, and (e) an aqueous carrier; (iv) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to grind at least a portion of the surface of the substrate, thereby polishing the substrate.

[0142] (19) In embodiment (19), the method of embodiment (18) is presented, wherein the negatively charged groups on the surface of the surface-modified colloidal silica particles comprise sulfonate groups, carboxylate groups, phosphonate groups, or a combination thereof.

[0143] (20) In embodiment (20), the method of embodiment (18) or (19) is presented, wherein the surface-modified colloidal silica particles have a particle size of about 90 nm to about 200 nm.

[0144] (21) In embodiment (21), the method of embodiment (20) is presented, wherein the surface-modified colloidal silica particles have a particle size of about 120 nm to about 180 nm.

[0145] (22) In embodiment (22), the method of any one of embodiments (18)-(21) is presented, wherein the pH of the polishing composition is about 1.5 to about 4.

[0146] (23) In embodiment (23), the method of embodiment (22) is presented, wherein the pH of the polishing composition is about 2 to about 3.5.

[0147] (24) In embodiment (24), the method of any one of embodiments (18)-(23) is presented, wherein the surface-modified colloidal silica particles are present in the polishing composition at a concentration of about 1.5 weight percent to about 3.5 weight percent.

[0148] (25) In embodiment (25), the method of embodiment (24) is presented, wherein the surface-modified colloidal silica particles are present in the polishing composition at a concentration of about 2 weight percent to about 3 weight percent.

[0149] (26) In embodiment (26), the method of any one of embodiments (18)-(25) is presented, wherein the iron compound comprises ferric nitrate or a hydrate thereof.

[0150] (27) In embodiment (27), the method of any one of embodiments (18)-(26) is presented, wherein the stabilizer comprises phosphoric acid, o-phosphoethanolamine, alendronic acid, acetic acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, glutaconic acid, muconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, or a combination thereof.

[0151] (28) In embodiment (28), the method of embodiment (27) is presented, wherein the stabilizer comprises malonic acid.

[0152] (29) In embodiment (29), the method of embodiment (27) or (28) is presented, wherein the stabilizer is present in the polishing composition at a concentration of about 0.0001 wt. % to about 0.01 wt. %.

[0153] (30) In embodiment (30), the method of any one of embodiments (18)-(29) is presented, wherein the corrosion inhibitor comprises glycine, alanine, lysine, arginine, histidine, or a combination thereof.

[0154] (31) In embodiment (31), the method of embodiment (30) is presented, wherein the corrosion inhibitor comprises alanine, glycine, lysine or arginine.

[0155] (32) In embodiment (32), the method of embodiment (31) is presented, wherein the corrosion inhibitor comprises glycine.

[0156] (33) In embodiment (33), the method of any one of embodiments (18)-(32) is presented, wherein the corrosion inhibitor is present in the polishing composition at a concentration of about 0.005 weight percent to about 1 weight percent.

[0157] (34) In embodiment (34), the method of embodiment (33) is presented, wherein the corrosion inhibitor is present in the polishing composition at a concentration of about 0.1 weight percent to about 0.5 weight percent.

[0158] (35) In embodiment (35), a method of any one of embodiments (18)-(34) is presented, wherein the substrate includes a tungsten layer and a silicon oxide layer on the surface of the substrate, and wherein at least a portion of the tungsten layer and at least a portion of the silicon oxide layer are ground to polish the substrate.

[0159] (36) In embodiment (36), the method of embodiment (35) is presented, wherein the grinding of at least a portion of the tungsten layer provides a tungsten removal rate, wherein the grinding of at least a portion of the silicon oxide layer provides a silicon oxide removal rate, and wherein the ratio of the tungsten removal rate to the silicon oxide removal rate is from about 0.5:1 to about 2.75:1.

[0160] Example

[0161] The following examples further illustrate the invention but, of course, should not be construed as limiting its scope in any way.

[0162] The following abbreviations are used herein: MPS refers to (3-mercaptopropyl)trimethoxysilane; W refers to tungsten; TEOS refers to tetraethoxysilane; and RR refers to removal rate.

[0163] Example 1

[0164] This example demonstrates the effectiveness of a chemical mechanical polishing composition comprising surface modified colloidal silica particles, an iron compound, a stabilizer, a corrosion inhibitor, and an aqueous vehicle according to an embodiment of the present invention. This example also demonstrates a method of chemical mechanical polishing a substrate according to an embodiment of the present invention.

[0165] Twelve different polishing compositions (Polishing Compositions 1A-1L) were prepared using one of seven different colloidal silica particles, as described in Tables 1 and 2. The different colloidal particles were prepared using the amounts of MPS and hydrogen peroxide described in Table 1. Colloidal silica particles P1 and P2 were colloidal silica particles obtained from FUSO Chemical Co. and were used without further modification and were used to prepare comparative polishing compositions 1A-1C. Colloidal silica particles P1 had an average particle size of 68 nm (FUSO, PL-3). Colloidal silica particles P2 had an average particle size of 120 nm (FUSO, PL-7).

[0166] Colloidal silica particles P3-P7 were surface modified using the procedures described herein and used to prepare polishing compositions 1D-1L as described in Tables 1 and 2. Surface modified colloidal silica particles P3-P7 were prepared from colloidal silica particles having an average particle size of 68 nm (FUSO, PL-3) or 120 nm (FUSO, PL-7), as described in Table 1. The process for surface modification of colloidal silica particles was as follows: A reactor (10 L) was charged with deionized water and colloidal silica dispersion to provide 3.5 kg of 10% (w / v) SiO2 colloidal dispersion. 0.5 g of KOH (45%) solution was added thereto to adjust the pH to approximately 8.5, followed by the addition of the amount of MPS indicated in Table 1 while stirring. The reactor was heated to 45° C. and maintained at this temperature for 48 hours, after which hydrogen peroxide (30%) was added at a 3:1 H2O2:MPS molar ratio and the solution was stirred at 45° C. for 6 hours. The reaction stoichiometry of MPS and H2O2 is illustrated in Table 1.

[0167] Table 1: Surface modified colloidal silica particles

[0168]

[0169] *See Table 2 for complete details on Polishing Compositions 1A-1L.

[0170] Polishing compositions 1A-1L were prepared using the following procedure: glycine (corrosion inhibitor), malonic acid (stabilizer), and ferric nitrate nonahydrate (iron compound) in the amounts indicated in Table 2 were added to a stirred deionized water solution, followed by the addition of the colloidal silica particles from Table 1. The pH of the composition was adjusted using nitric acid (70%) or potassium hydroxide (45%) as needed to obtain the pH indicated in Table 2. Hydrogen peroxide (oxidizing agent) was added to the slurry prior to polishing. In addition, each polishing composition contained 0.001 wt.% of a biocide (KATHON TM LX).

[0171] Polishing compositions 1A-1F are comparative. Polishing compositions 1A-1C contain unmodified colloidal silica particles. Polishing compositions 1D-1F contain surface-modified colloidal silica particles having an average particle size of 68 nm.

[0172] Polishing Compositions 1G-1L are of the present invention, and in particular, each of Polishing Compositions 1G-1L contains surface-modified colloidal silica particles having a particle size of about 90 nm to about 350 nm.

[0173] Table 2: Polishing composition

[0174]

[0175] Polishing compositions 1A-1L were used to polish substrates comprising tungsten and TEOS to evaluate blanket polishing performance. The following polishing conditions were used: Tool = MIRRA TM , pad = IC1010 or E6088, slurry flow rate = 180 mL / min, platen speed / head speed = 100 / 101 rpm, inner tube pressure / retaining ring pressure / membrane pressure = 207 / 414 / 207 hPa, ex.situ conditioner = SAESOL TM C1 20N.

[0176] The polishing results are described in Table 3.

[0177] Table 3: Polishing composition and blanket polishing performance as a function of silicon oxide particles (down force = 207 hPa)

[0178]

[0179] As is clear from the results set forth in Table 3, the inventive polishing composition 1G containing surface-modified colloidal silica particles having a particle size of 120 nm exhibited a blanket tungsten removal rate of 45.2 nm / min and a TEOS removal rate of 41.5 nm / min. The tungsten removal rate of the polishing composition 1G was approximately 15% higher (i.e., 39.2 nm / min) than the tungsten removal rate of the polishing composition 1A containing unmodified colloidal silica particles having a particle size of 68 nm. In addition, the TEOS removal rate of the polishing composition 1G was approximately twice the TEOS removal rate of the polishing composition 1A (i.e., 21.6 nm / min).

[0180] A similar comparison between Polishing Compositions 1G and 1C showed that Polishing Composition 1G exhibited a tungsten removal rate that was approximately 3 times that of Comparative Polishing Composition 1C and a TEOS removal rate that was approximately 1.8 times that of Comparative Polishing Composition 1C (15.4 nm / min and 23.1 nm / min, respectively).

[0181] Furthermore, it is clear from the results illustrated in Table 3 that pH affects oxide removal rate capability. For example, Comparative Polishing Compositions 1A and 1B (pH 2.2 and pH 3.5, respectively), which are identical except for pH, exhibit different oxide removal rates (i.e., 21.6 nm / min and 8.2 nm / min, respectively), while exhibiting approximately the same tungsten removal rates (i.e., 39.2 nm / min and 38.0 nm / min, respectively). This shows that the comparative polishing compositions have limited formulation space due to the extremely low oxide removal rates at higher pH values. In contrast, the polishing compositions of the present invention have an extended pH capability in terms of oxide removal rate. For example, Polishing Composition 1J containing surface-modified colloidal silica particles having an average particle size of about 120 nm and a pH of 3.5 has a TEOS removal rate of 26.2 nm / min, i.e., more than 3 times the oxide removal rate (i.e., 8.2 nm / min) of Comparative Polishing Composition 1B containing unmodified colloidal silica particles having an average particle size of about 68 nm.

[0182] Example 2

[0183] This example demonstrates the effectiveness of a chemical mechanical polishing composition comprising surface modified colloidal silica particles, an iron compound, a stabilizer, a corrosion inhibitor, and an aqueous vehicle according to an embodiment of the present invention. This example also demonstrates the pattern polishing performance of the composition of the present invention comprising these components.

[0184] The patterned substrates including a tungsten layer and a silicon oxide layer were polished separately using polishing compositions 1A-1K described in Example 1. The polishing parameters were as follows: Tool = MIRRA TM , slurry flow rate = 180 mL / min, platen speed / head speed = 100 / 101 rpm, IT / RR / MP = 207 / 414 / 207 hPa, off-site conditioner = SAESOL TM C1 20N. Patterns were prepared and then polished using compositions 1A to 1K and commercially available W8051 polishing slurry to endpoint + 10%. W8051 tungsten polishing slurry was obtained from Cabot Microelectronics Corp. (Aurora, IL) and used as received in combination with 2% hydrogen peroxide. Polishing was performed using compositions 1A to 1K with a fixed polishing time of 30 seconds. Erosion data are averages of 3 line array sites. Local erosion data are averages of 2 isolated lines at each of the 3 sites.

[0185] The polishing performance results are presented in Table 4.

[0186] Table 4: Pattern polishing performance as a function of silicon oxide particles

[0187]

[0188] a 0.18 x 0.18 μm array erosion is determined by measuring the difference between the tops of the lines in the array and the associated field oxide. Positive values ​​correspond to arrays that are recessed relative to the field oxide, and negative values ​​correspond to arrays that are protruding (convex) relative to the field oxide. b 1 x 1 μm array erosion is determined by measuring the difference between the oxide in the array and the oxide in the field. Positive values ​​correspond to an array that is recessed relative to the field oxide, and negative values ​​correspond to an array that is protruding (convex) relative to the field oxide.

[0189] As is clear from the results set forth in Table 4, the polishing compositions of the present invention containing surface-modified colloidal silica particles exhibit improved pattern performance. For example, when the inventive polishing composition 1G and the polishing composition 1H are compared with the comparative polishing composition 1A, the compositions of the present invention exhibit higher field oxide loss (about 18% higher), lower erosion for 0.18×0.18 μm line arrays (i.e., less than 10% erosion in the case of the polishing composition 1G, and less than 50% erosion in the case of the polishing composition 1H), and lower erosion for 1×1 μm line arrays (i.e., about 65% erosion in the case of the polishing composition 1G, and less than 75% erosion in the case of the polishing composition 1H).

[0190] The advantages of the compositions of the present invention are particularly significant in the case of localized corrosion. For example, Polishing Composition 1G and Polishing Composition 1H of the present invention exhibited less than 10% of localized corrosion for 0.18 μm isolated lines (i.e., 0.9 nm vs. 15.4 nm) of Comparative Polishing Composition 1A, and less than 33% of localized corrosion for 1×1 μm isolated lines (i.e., 7.4 nm and 7.5 nm vs. 24.6 nm).

[0191] In addition, it was found that the compositions of the present invention can be used in a wide range of formulations including higher pH values ​​(e.g., 3.5). For example, the improved pattern performance of the present formulations was demonstrated by comparing the present polishing composition 1J with the comparative polishing composition 1F. Compared to the comparative polishing composition 1F, the present polishing composition 1J exhibited higher oxide loss (more than 35% higher oxide loss, i.e., 13.5 nm vs. 9.9 nm), as well as lower erosion for both the 0.18×0.18 μm array (erosion reduced to less than 40%, i.e., 7.1 nm vs. 18.7 nm) and the 1×1 μm array (erosion reduced to less than 35%, i.e., 9.5 nm vs. 28.1 nm). In addition, the local erosion of the present polishing composition 1J for the 0.18 μm isolated line was only 20% of the local erosion of the comparative polishing composition 1F (i.e., 2.0 nm vs. 10.7 nm) and for the 1 μm isolated line was only 30% of the polishing composition 1F (i.e., 6.1 nm vs. 20.7 nm).

[0192] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0193] The use of the terms "one" and "a kind" and "the" and "at least one (kind)" and similar indicators in describing the scope of the present invention (particularly the scope of the appended claims) should be understood to include the singular and the plural, unless otherwise specified herein or the context clearly contradicts. The use of the term "at least one (kind)" after a list of one or more items (e.g., "at least one (kind) of A and B") is interpreted as meaning one (kind) item (A or B) selected from the listed items or any combination of two (kinds) or more (kinds) items (A and B) of the listed items, unless otherwise specified herein or the context clearly contradicts. The terms "comprising", "having", "including", and "containing" should be understood as open terms (i.e., meaning "including, but not limited to"), unless otherwise specified. The enumeration of numerical ranges herein is used only as a shorthand method of referring to each independent value falling within the range individually, unless otherwise specified herein, and each independent value is introduced in the specification as if it were individually listed here. All methods described herein can be performed in any suitable order, unless otherwise specified herein or clearly contradicted by the context. The use of any and all examples, or exemplary language (e.g., "for example") provided herein is intended only to better illustrate the present invention and is not intended to limit the scope of the present invention unless otherwise specified. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the present invention.

[0194] Preferred embodiments of the present invention are described herein, including the best mode of carrying out the present invention known to the inventor. By reading the above description, changes in those preferred embodiments will become clear to those of ordinary skill in the art. The inventors hope that the technicians will appropriately adopt such changes, and the inventors hope that the present invention will be practiced in a manner different from that specifically described herein. Therefore, the present invention includes all modifications and equivalents of the themes listed in the appended claims as allowed by applicable law. In addition, the present invention covers any combination of the above-mentioned elements in all possible variations thereof, unless otherwise stated herein or clearly contradictory to the context.

Claims

1. A chemical mechanical polishing composition for polishing a substrate comprising a tungsten layer and a silicon oxide layer, comprising: (a) surface-modified colloidal silica particles comprising negatively charged groups on the surface of the particles, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of 120 nm to 200 nm, and a zeta potential of -5 mV to -10 mV at a pH of 2 to 2.4, and the surface-modified colloidal silica particles are present in the polishing composition at a concentration of 2 wt % to 3 wt %, (b) an iron compound comprising ferric nitrate or a hydrate thereof, the iron compound being present in the polishing composition at a concentration of 0.001 wt.% to 0.005 wt.%, (c) a stabilizer, the stabilizer being present in the polishing composition at a concentration of 0.005 wt. % to 0.01 wt. %, (d) a corrosion inhibitor comprising alanine, glycine, lysine, or arginine, wherein the corrosion inhibitor is present in the polishing composition at a concentration of 0.1 wt. % to 0.5 wt. %, and (e) Aqueous vehicle.

2. The polishing composition according to claim 1, wherein The negatively charged groups on the surface of the surface-modified colloidal silica particles include sulfonate groups, carboxylate groups, phosphonate groups, or a combination thereof.

3. The polishing composition according to claim 1, wherein The surface-modified colloidal silica particles have a particle size of about 120 nm to about 180 nm.

4. The polishing composition according to claim 1, wherein The corrosion inhibitor comprises glycine.

5. A method for chemical mechanical polishing of a substrate, comprising: (i) providing a substrate, the substrate comprising a tungsten layer on a surface of the substrate and a silicon oxide layer on the surface of the substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition comprising: (a) surface-modified colloidal silica particles comprising negatively charged groups on the surface of the particles, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of 120 nm to 200 nm, and a zeta potential of -5 mV to -10 mV at a pH of 2 to 2.4, and the surface-modified colloidal silica particles are present in the polishing composition at a concentration of 2 wt % to 3 wt %, (b) an iron compound comprising ferric nitrate or a hydrate thereof, the iron compound being present in the polishing composition at a concentration of 0.001 wt.% to 0.005 wt.%, (c) a stabilizer, the stabilizer being present in the polishing composition at a concentration of 0.005 wt. % to 0.01 wt. %, (d) a corrosion inhibitor comprising alanine, glycine, lysine, or arginine, wherein the corrosion inhibitor is present in the polishing composition at a concentration of 0.1 wt. % to 0.5 wt. %, and (e) an aqueous carrier; (iv) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the surface of the substrate, thereby polishing the substrate.

6. The method according to claim 5, wherein: The negatively charged groups on the surface of the surface-modified colloidal silica particles include sulfonate groups, carboxylate groups, phosphonate groups, or a combination thereof.

7. The method according to claim 5, wherein: The surface-modified colloidal silica particles have a particle size of about 120 nm to about 180 nm.

8. The method according to claim 5, wherein: The corrosion inhibitor comprises glycine.

9. The method according to claim 5, wherein: At least a portion of the tungsten layer and at least a portion of the silicon oxide layer are ground to polish the substrate.

10. The method according to claim 9, wherein: The polishing of at least a portion of the tungsten layer provides a tungsten removal rate, wherein the polishing of at least a portion of the silicon oxide layer provides a silicon oxide removal rate, and wherein a ratio of the silicon oxide removal rate to the tungsten removal rate is about 0.80:1 to about 1:1.

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