Polishing composition and method having high selectivity for silicon nitride and polysilicon compared with silicon oxide

Abstract

To provide: a polishing composition and a method for providing relatively high removal rate of SiN and polysilicon; and a polishing composition exhibiting selective removal of SiN in preference to silicon oxide during CMP.SOLUTION: The present invention provides a polishing composition having a pH of about 5 to about 8 in a chemical-mechanical polishing composition including: (a) an abrasive containing ceria particles; (b) a cationic polymer selected from a cationic homopolymer, a cationic copolymer containing at least one cationic monomer and at least one nonionic monomer, and a combination thereof; (c) a quaternary ammonium salt or a quaternary phosphonium salt; and (d) water. The present invention also provides a method for chemically-mechanically polishing a substrate, particularly a substrate containing silicon oxide, silicon nitride and / or polysilicon, by contacting the substrate with the chemical-mechanical polishing composition of the present invention.SELECTED DRAWING: None

Description

[Background technology]

[0001] Compositions and methods for planarizing or polishing the surface of a substrate are well known in the art. Polishing compositions (also known as polishing slurries) typically contain an abrasive material in a liquid carrier and are applied to a surface by contacting the surface with a polishing pad saturated with the polishing composition. Typical abrasive materials include silicon dioxide, cerium oxide, aluminum oxide, zirconium oxide, and tin oxide. Polishing compositions are typically used in conjunction with a polishing pad (e.g., a polishing cloth or disk). Instead of, or in addition to, being suspended in the polishing composition, the abrasive material can be incorporated into the polishing pad.

[0002] In the fabrication of advanced memory and logic semiconductor devices, integrated circuit (IC) schemes require the selective removal of polysilicon and / or silicon nitride (SiN) layers. Once the polysilicon and silicon nitride materials are removed, a silicon oxide layer is exposed, which is desired to remain intact for further deposition and IC fabrication steps. While not intended to be limited to the examples presented here, one example of this process is the removal of silicon nitride material over silicon oxide for a reverse shallow trench isolation (R-STI) process. Furthermore, for 3D NAND device fabrication, where an oxide or silicon nitride layer is formed on a silicon substrate containing a high aspect ratio, selectivity for polysilicon and silicon nitride polishing over silicon oxide (SiO) polishing is similarly required. Vias are then formed by etching or photolithography, and a polysilicon layer is deposited to fill the vias. Due to variations in the depth of the formed trenches or vias, it is typically necessary to deposit an excess of dielectric material (e.g., SiN or polysilicon) on top of the substrate to ensure complete filling of all trenches and vias. The excess dielectric material is then typically removed by a chemical mechanical planarization (CMP) process to expose the silicon oxide layer as a stop layer, once the silicon oxide is exposed a high degree of flatness and surface uniformity is desired.

[0003] Typically, two CMP steps have been used to emphasize selectivity for polysilicon and / or SiN polishing over oxide polishing. Thus, the oxide layer has served as a stop layer during the chemical mechanical planarization process. Many current slurries offer moderate SiN rates and moderate selectivity, limiting their usefulness. For example, low to moderate polishing rates can limit throughput, while low to moderate polysilicon / oxide or SiN / oxide selectivity limits the usefulness of current slurry technology for larger structures with thicker polysilicon or silicon nitride coatings.

[0004] Dielectric materials on substrates are typically polished using conventional abrasive-containing polishing compositions. However, it has been found that polishing silicon oxide or polysilicon using conventional abrasive-containing polishing compositions can result in over-polishing or under-polishing of the substrate surface. This over-polishing phenomenon can result in the formation of depressions in pattern oxide features, known as dishing. Dishing of substrate features is undesirable because it can cause poor insulation between transistors and transistor components, resulting in short circuits, which can adversely affect device fabrication. Conversely, under-polishing of the substrate can result in incomplete or partial removal of the polysilicon and / or SiN layer, further preventing the silicon oxide stop layer from being exposed, resulting in insufficient planarity or electrical insulation, which adversely affects device quality and performance. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, there remains a need in the art for polishing compositions and methods that provide relatively high removal rates of SiN and polysilicon, as well as selective removal of SiN over silicon oxide during CMP. [Means for solving the problem]

[0006] The present invention provides a chemical mechanical polishing composition comprising (a) an abrasive containing ceria particles, (b) a cationic polymer selected from cationic homopolymers, cationic copolymers containing at least one cationic monomer and at least one nonionic monomer, and combinations thereof, (c) a quaternary ammonium salt or a quaternary phosphonium salt, and (d) water, the polishing composition having a pH of about 5 to about 8.

[0007] The present invention also provides a method for chemically mechanically polishing a substrate, the method comprising the steps of: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition comprising: (a) an abrasive containing ceria particles; (b) a cationic polymer selected from a cationic homopolymer, a cationic copolymer containing at least one cationic monomer and at least one nonionic monomer, and combinations thereof; (c) a quaternary ammonium salt or a quaternary phosphonium salt; and (d) water, the chemical mechanical polishing composition having a pH of about 5 to about 8; (iv) contacting the polishing pad and the chemical mechanical polishing composition with the substrate; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade a portion of the surface of the substrate, thereby polishing the substrate. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention provides a chemical-mechanical polishing composition that comprises, consists essentially of, or consists of (a) an abrasive containing ceria particles; (b) a cationic polymer selected from cationic homopolymers, cationic copolymers containing at least one cationic monomer and at least one nonionic monomer, and combinations thereof; (c) a quaternary ammonium salt or a quaternary phosphonium salt; and (d) water, the polishing composition having a pH of about 5 to about 8.

[0009] The chemical-mechanical polishing composition includes an abrasive, where the abrasive comprises, consists essentially of, or consists of ceria particles.

[0010] As known to those skilled in the art, ceria is an oxide of the rare earth metal cerium, also known as ceric oxide, cerium oxide (e.g., cerium(IV) oxide), or cerium dioxide. Cerium(IV) oxide (CeO2) can be formed by calcining cerium oxalate or cerium hydroxide. Cerium also forms cerium(III) oxide, e.g., Ce2O3. Ceria abrasives can be any one or more of these or other ceria oxides.

[0011] The ceria abrasive can be any suitable type of ceria. In one embodiment, the ceria is wet-process ceria. As used herein, "wet-process" ceria refers to ceria prepared by precipitation, condensation-polymerization, or similar processes (as opposed to, for example, fumed ceria or pyrogenic ceria). While not wishing to be bound by any particular theory, wet-process ceria is believed to include spherical ceria particles and / or smaller agglomerated ceria particles. An exemplary wet-process ceria is HC-60™ ceria or HC-90™ ceria, commercially available from Rhodia.

[0012] In another embodiment, the polishing composition contains abrasive particles comprising cubic cerium oxide abrasive particles suspended in a liquid carrier. "Cubic" means that the ceria abrasive particles are cubic in shape, i.e., substantially cubic. Stated differently, cubic ceria abrasive particles are cubic in shape or nature. However, it is understood that the edge dimensions, corners, and corner angles need not be exactly or precisely those of a perfect cube. For example, cubic abrasive particles may have slightly rounded or chipped corners, slightly rounded edges, edge dimensions that are not exactly equal to one another, corner angles that are not exactly 90 degrees, and / or other minor irregularities, and still retain the basic cubic shape. One skilled in the art can readily recognize (e.g., via scanning electron microscopy or transmission electron microscopy) that cubic ceria abrasive particles are cubic in shape, with generally accepted tolerances for particle growth and deagglomeration.

[0013] As used herein, a chemical-mechanical polishing composition containing a cubic ceria abrasive is a chemical-mechanical polishing composition in which at least 25 percent of the abrasive particles are cubic in nature (cubic in shape, as described above). In preferred embodiments, at least 40 percent (e.g., at least 60 percent or at least 80 percent) of the abrasive particles are cubic in nature. As noted above, cubic ceria abrasive particles can be easily evaluated and counted using TEM or SEM images, for example, at magnifications ranging from about 10,000x to about 500,000x. SEM or TEM images show abrasive particles having faces with four sides of similar lengths (e.g., within 20 percent of each other). The images also show that adjacent sides are, for example, approximately orthogonal and form angles of about 90 degrees (e.g., within a range of about 80 to about 100 degrees). To determine whether a ceria abrasive composition contains cubic ceria abrasive particles, SEM or TEM observations are performed on randomly selected particles (i.e., more than 200), allowing for a statistical analysis to determine the percentage of particles having square faces. The particles retained must be such that their images are sufficiently visible on the micrograph. Some of the particles may exhibit some defects on either their surface and / or one or more of their corners and still be considered cubic.

[0014] The cubic ceria abrasive particles can be substantially pure ceria abrasive particles (within typical tolerances for impurities) or doped ceria abrasive particles. Doped ceria abrasive particles can contain interstitial dopants (dopants that occupy spaces in the lattice that are normally unoccupied) or substitutional dopants (dopants that occupy spaces in the lattice normally occupied by cerium or oxygen atoms). Such dopants can include virtually any metal atom, including, for example, Ca, Mg, Zn, Zr, Sc, or Y.

[0015] Further description of suitable cubic ceria can be found in co-pending applications filed on even date herewith, such as application Ser. No. 62 / 924,328.

[0016] The wet process ceria particles can have any suitable average size (i.e., average particle size). The particle size of a particle is the diameter of the smallest sphere encompassing the particle. If the average particle size of the ceria particles is too small, the polishing composition may not exhibit a sufficient removal rate. In contrast, if the average particle size of the ceria particles is too large, the polishing composition may exhibit undesirable polishing performance, such as poor substrate uniformity. Thus, the ceria particles can have an average particle size of about 60 nm or more, for example, about 65 nm or more, about 70 nm or more, about 75 nm or more, about 80 nm or more, about 85 nm or more, or about 90 nm or more. Alternatively or additionally, the ceria particles can have an average particle size of about 120 nm or less, for example, about 115 nm or less, about 110 nm or less, about 105 nm or less, or about 100 nm or less. Thus, the ceria particles can have an average particle size bounded by any two of the above-mentioned endpoints. For example, the ceria particles can have an average particle size of about 60 nm to about 120 nm, e.g., about 60 nm to about 115 nm, about 60 nm to about 110 nm, about 60 nm to about 105 nm, about 60 nm to about 100 nm, about 65 nm to about 120 nm, about 65 nm to about 115 nm, about 70 nm to about 120 nm, about 70 nm to about 115 nm, about 75 nm to about 120 nm, about 75 nm to about 115 nm, about 80 nm to about 120 nm, about 80 nm to about 115 nm, about 85 nm to about 120 nm, about 85 nm to about 115 nm, about 90 nm to about 120 nm, or about 90 nm to about 115 nm. For non-spherical wet-process ceria particles, e.g., small aggregates, the size of the particle is the diameter of the smallest sphere encompassing the particle. The particle size of the ceria particles can be measured using any suitable technique, for example, laser diffraction or dynamic light scattering techniques. Suitable particle size measurement instruments are available, for example, from Malvern Instruments Ltd. (Malvern, UK).

[0017] Ceria particles are preferably colloidally stable in the inventive polishing composition. The term colloidal refers to the suspension of ceria particles in water. Colloidal stability refers to the maintenance of this suspension over time. In the context of this invention, an abrasive is considered colloidally stable if, when placed in a 100 mL graduated cylinder and left unstirred for two hours, the difference between the concentration of particles in the bottom 50 mL of the graduated cylinder ([B] in g / mL) and the concentration of particles in the top 50 mL of the graduated cylinder ([T] in g / mL), divided by the initial particle concentration in the abrasive composition ([C] in g / mL), is 0.5 or less (i.e., {[B]-[T]} / [C]≦0.5). More preferably, the value of [B]-[T] / [C] is 0.3 or less, and more preferably 0.1 or less.

[0018] The polishing composition can contain any suitable amount of ceria abrasive. If the polishing composition of the present invention contains too little ceria abrasive, the composition may not exhibit a sufficient removal rate. In contrast, if the polishing composition contains too much ceria abrasive, the composition may exhibit undesirable polishing performance, may not be cost-effective, and / or may lack stability. The polishing composition can contain about 1% by weight or less of ceria, for example, about 0.9% by weight or less, about 0.8% by weight or less, about 0.7% by weight or less, about 0.6% by weight or less, or about 0.5% by weight or less of ceria. Alternatively, or in addition, the polishing composition can contain about 0.01% by weight or more of ceria, for example, about 0.05% by weight or more, about 0.1% by weight or more, about 0.2% by weight or more, about 0.3% by weight or more, about 0.4% by weight or more, or about 0.5% by weight or more of ceria. Thus, the polishing composition can contain ceria in an amount bounded by any two of the above endpoints. For example, the polishing composition can contain about 0.01% by mass to about 1% by mass of ceria, e.g., about 0.1% by mass to about 0.9% by mass, about 0.1% by mass to about 0.8% by mass, about 0.1% by mass to about 0.7% by mass, about 0.1% by mass to about 0.6% by mass, about 0.1% by mass to about 0.5% by mass, about 0.05% by mass to about 1% by mass, about 0.05% by mass to about 0.9% by mass, about 0.05% by mass to about 0.8% by mass, about 0.2% by mass to about 0.7% by mass, about 0.2% by mass to about 0.6% by mass, about 0.2% by mass to about 0.5% by mass, or about 0.3% by mass to about 0.6% by mass of ceria.

[0019] The polishing composition comprises a cationic polymer selected from cationic homopolymers, cationic copolymers comprising at least one cationic monomer and at least one nonionic monomer, and combinations thereof.

[0020] The cationic homopolymer can be any suitable cationic homopolymer composed essentially of cationic monomer repeat units. For example, the cationic homopolymer can be any suitable cationic polymer composed essentially of quaternary amine groups as repeat units. The quaternized amine groups can be acyclic or incorporated into a cyclic structure. The quaternized amine groups include a tetrasubstituted nitrogen atom substituted with four groups independently selected from alkyl, alkenyl, aryl, arylalkyl, acrylamide, or methacrylate groups, or, when incorporated into a cyclic structure, include either a heterocyclic saturated ring containing the nitrogen atom and further substituted with two groups as described above, or an N-heterocyclic group (e.g., imidazole or pyridine) having an additional group attached to the nitrogen atom as described above. The quaternized amine groups are positively charged (i.e., they are cations that have an anionic moiety attached, thereby forming a salt). The cationic polymers of the present invention can be further modified by chemical reactions such as alkylation, acylation, or ethoxylation to alter the solubility, viscosity, or other physical parameters of the cationic polymer. Suitable quaternary amine monomers include, for example, quaternized vinylimidazole (vinylimidazolium), methacryloyloxyethyltrimethylammonium (MADQUAT), diallyldimethylammonium (DADMAC), methacrylamidopropyltrimethylammonium (MAPTAC), epichlorohydrindimethylamine (epi-DMA), and combinations thereof.

[0021] In some embodiments, the cationic polymer may be a copolymer comprising at least one cationic monomer and at least one nonionic monomer, wherein the at least one cationic monomer comprises either more than 50% of the copolymer on a molar basis or less than or equal to about 50% of the copolymer on a molar basis. The cationic monomer may be as described herein in connection with cationic homopolymers. Non-limiting examples of suitable nonionic monomers include vinylpyrrolidone, vinylcaprolactam, vinylimidazole, acrylamide, vinyl alcohol, polyvinyl formal, polyvinyl butyral, poly(vinyl phenyl ketone), vinylpyridine, polyacrolein, ethylene, propylene, styrene, and combinations thereof.

[0022] Suitable cationic polymers include, for example, quaternized poly(vinylimidazole) methyl sulfate, poly(methacryloyloxyethyltrimethylammonium) chloride (polyMADQUAT), poly(diallyldimethylammonium) chloride (polyDADMAC), poly(dimethylamine-co-epichlorohydrin), poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] (i.e., polyquaternium-2), acrylates, ... These include copolymers of vinylamide and diallyldimethylammonium (Polyquaternium-7), copolymers of vinylpyrrolidone and quaternized dimethylaminoethyl methacrylate (Polyquaternium-11), copolymers of vinylpyrrolidone and quaternized vinylimidazole (i.e., Polyquaternium-16), terpolymers of vinylcaprolactam, vinylpyrrolidone, and quaternized vinylimidazole (i.e., Polyquaternium-46), and 3-methyl-1-vinylimidazolium methylsulfate-N-vinylpyrrolidone copolymer (i.e., Polyquaternium-44), copolymers of vinylpyrrolidone and diallyldimethylammonium. Additionally, suitable cationic polymers include personal care cationic polymers such as Luviquat® Supreme, Luviquat® Hold, Luviquat® UltraCare, Luviquat® FC370, Luviquat® FC550, Luviquat® FC552, Luviquat® Excellence, and combinations thereof.

[0023] When the polishing composition includes a cationic homopolymer, the polishing composition can include any suitable amount of cationic homopolymer. For example, the polishing composition can include about 1 ppm or more of cationic homopolymer, such as about 5 ppm or more, about 10 ppm or more, about 15 ppm or more, about 20 ppm or more, about 25 ppm or more, or about 30 ppm or more, or about 50 ppm or more of cationic homopolymer. Alternatively, or in addition, the polishing composition can include about 200 ppm or less of cationic homopolymer, such as about 175 ppm or less, about 150 ppm or less, about 125 ppm or less, about 100 ppm or less, about 90 ppm or less, about 85 ppm or less, about 80 ppm or less, about 75 ppm or less, about 70 ppm or less, about 65 ppm or less, about 60 ppm or less, about 55 ppm or less, or about 50 ppm or less of cationic homopolymer. Thus, the polishing composition can include an amount of cationic homopolymer bounded by any two of the above endpoints. For example, the polishing composition may contain from about 1 ppm to about 200 ppm of cationic homopolymer, e.g., from about 1 ppm to about 80 ppm, from about 1 ppm to about 75 ppm, from about 1 ppm to about 70 ppm, from about 1 ppm to about 65 ppm, from about 1 ppm to about 60 ppm, from about 5 ppm to about 125 ppm, from about 10 ppm to about 100 ppm, from about 10 ppm to about 90 ppm, or from about 10 ppm to about 85 ppm. About 10 ppm to about 80 ppm, about 10 ppm to about 75 ppm, about 10 ppm to about 70 ppm, about 10 ppm to about 65 ppm, about 10 ppm to about 60 ppm, about 20 ppm to about 200 ppm, about 20 ppm to about 125 ppm, about 20 ppm to about 100 ppm, about 20 ppm to about 90 ppm, about 20 ppm to about 85 ppm, about 20 ppm to about 80 ppm, about 20 ppm to about 75 ppm, about 20 ppm to about 70 ppm, about 20 ppm The cationic homopolymer may be present in an amount of from about 20 ppm to about 65 ppm, from about 20 ppm to about 60 ppm, from about 30 ppm to about 200 ppm, from about 30 ppm to about 150 ppm, from about 30 ppm to about 100 ppm, from about 30 ppm to about 90 ppm, from about 30 ppm to about 85 ppm, from about 30 ppm to about 80 ppm, from about 30 ppm to about 75 ppm, from about 30 ppm to about 70 ppm, from about 30 ppm to about 65 ppm, or from about 30 ppm to about 60 ppm.

[0024] When the polishing composition includes a cationic copolymer, the polishing composition can include any suitable amount of the cationic copolymer, such as about 1 ppm or more of the cationic copolymer, e.g., about 10 ppm or more, about 20 ppm or more, about 50 ppm or more, about 100 ppm or more, about 120 ppm or more, about 130 ppm or more, about 140 ppm or more, about 150 ppm or more, about 160 ppm or more, about 170 ppm or more, about 180 ppm or more, about 190 ppm or more, or about 200 ppm or more of the cationic copolymer. Alternatively or additionally, the polishing composition can comprise about 1000 ppm or less of the cationic copolymer, e.g., about 950 ppm or less, about 900 ppm or less, about 850 ppm or less, about 800 ppm or less, about 750 ppm or less, about 700 ppm or less, about 650 ppm or less, about 600 ppm or less, about 505 ppm or less, or about 500 ppm or less of the cationic copolymer. Thus, the polishing composition can comprise the cationic copolymer in an amount bounded by any two of the above-mentioned endpoints. For example, the polishing composition may contain from about 1 ppm to about 1000 ppm of cationic copolymer, e.g., from about 1 ppm to about 750 ppm, from about 1 ppm to about 600 ppm, from about 1 ppm to about 500 ppm, from about 10 ppm to about 950 ppm, from about 100 ppm to about 900 ppm, from about 100 ppm to about 850 ppm, from about 100 ppm to about 800 ppm, from about 100 ppm to about 750 ppm, from about 100 ppm to about 70 The cationic copolymer may be present in an amount of 0 ppm, about 100 ppm to about 650 ppm, about 100 ppm to about 600 ppm, about 100 ppm to about 550 ppm, about 100 ppm to about 500 ppm, about 110 ppm to about 500 ppm, about 120 ppm to about 500 ppm, about 130 ppm to about 500 ppm, about 140 ppm to about 500 ppm, or about 150 ppm to about 500 ppm.

[0025] The polishing composition comprises a water-soluble quaternary ammonium salt or a quaternary phosphonium salt. In some embodiments, the quaternary ammonium salt is [ka] wherein R 1 ~R4 is C1~C 12 Alkyl, C1-C 12 Alkenyl, C6-C 10 independently selected from aryl, acrylamide, methacrylate, primary or secondary alcohol groups; [ka] is an anion. If the R group is C 16 If the alkyl, alkenyl, or aryl type contains chains of lengths greater than or equal to 1000, undesirable silicon nitride removal rates and selectivity to silicon oxide may be observed. 16 Contains less than 10 R groups.

[0026] Non-limiting examples include anions, [ka] can include common anion types such as fluoride, chloride, bromide, iodide, nitrate, nitrite, sulfate, methylsulfate, and phosphate. The preferred anion is chloride or bromide. Acetate and anions similar to those of acetate are less preferred due to an observed loss of selectivity to oxides.

[0027] Quaternary phosphonium salts are [ka] where R 1 ~R 4 is C1~C 12 Alkyl, C6-C 10 Aryl and C1-C 12 alkenyl, wherein [ka] is the anion. The phosphonium salt anion may be as described herein in connection with the quaternary ammonium salt anion.

[0028] In some embodiments, the polishing composition has a molecular weight of about 75 g / mol or greater (e.g., about 80 g / mol or greater, about 90 g / mol or greater, about 100 g / mol or greater, about 110 g / mol or greater, about 120 g / mol or greater, about 130 g / mol or greater, or about 140 g / mol or greater). [ka] Non-limiting examples of suitable quaternary ammonium salts include tetramethylammonium salts, tetraethylammonium salts, tetrapropylammonium salts, tetrabutylammonium salts, tetrapentylammonium salts, tetrahexylammonium salts, tetraheptylammonium salts, tetraoctylammonium salts, tetradodecylammonium salts, diallyldimethylammonium salts and derivatives, benzalkonium salts, N-alkylmethylimidazolium salts, N,N-diarylimidazolium salts, N-alkylpyridinium salts, didecyldimethylammonium salts, tetrabenzylammonium salts, benzyldimethyldecylammonium salts, benzyldimethylhexylammonium salts, benzyldimethyloctylammonium salts, benzyldodecyldimethylammonium salts, benzyltributylammonium salts, benzyltriethylammonium salts, benzyl Examples of suitable ammonium salts include trimethylammonium salt, decyltrimethylammonium salt, didodecyldimethylammonium salt, dodecylethyldimethylammonium salt, dodecyltrimethylammonium salt, hexyltrimethylammonium salt, methyltrioctylammonium salt, tributylmethylammonium salt, tridodecylmethylammonium salt, triethylhexylammonium salt, triethylmethylammonium salt, trimethyloctylammonium salt, trimethylphenylammonium salt, trihexyltetradecylammonium salt, [(3-methacryloylamino)propyl]trimethylammonium salt, (3-acrylamidopropyl)trimethylammonium salt, 2-(acryloyloxy)ethyltrimethylammonium salt, (vinylbenzyl)trimethylammonium salt, choline salt, and tris(2-hydroxyethyl)methylammonium salt.Non-limiting examples of suitable quaternary phosphonium salts include benzyltriphenylphosphonium salts, dimethyldiphenylphosphonium salts, tetrabutylphosphonium salts, tetramethylphosphonium salts, tetraphenylphosphonium salts, tetrapropylphosphonium salts, tetraoctylphosphonium salts, butyltriphenylphosphonium salts, tetraethylphosphonium salts, tributyldodecylphosphonium salts, ethyltriphenylphosphonium salts, hexyltriphenylphosphonium salts, heptyltriphenylphosphonium salts, isopropyltriphenylphosphonium salts, methyltriphenylphosphonium salts, tributylmethylphosphonium salts, tributyloctylphosphonium salts, triphenylpropylphosphonium salts, and tributylhexylphosphonium salts.

[0029] The polishing composition can contain any suitable amount of quaternary ammonium salt or quaternary phosphonium salt. For example, the polishing composition can contain about 10 ppm or more of quaternary ammonium salt or quaternary phosphonium salt, for example, about 25 ppm or more, about 50 ppm or more, or about 100 ppm or more. The polishing composition can contain about 110 ppm or more, about 120 ppm or more, about 130 ppm or more, about 140 ppm or more, about 150 ppm or more, about 160 ppm or more, about 170 ppm or more, about 180 ppm or more, about 190 ppm or more, or about 200 ppm or more of quaternary ammonium salt or quaternary phosphonium salt. Alternatively or additionally, the polishing composition can contain about 1000 ppm or less of a quaternary ammonium salt or a quaternary phosphonium salt, for example, about 950 ppm or less, about 900 ppm or less, about 850 ppm or less, about 800 ppm or less, about 750 ppm or less, about 700 ppm or less, about 650 ppm or less, about 600 ppm or less, about 505 ppm or less, or about 500 ppm or less of a quaternary ammonium salt or a quaternary phosphonium salt. Thus, the polishing composition can contain a quaternary ammonium salt or a quaternary phosphonium salt in an amount bounded by any two of the above-mentioned endpoints. For example, the polishing composition may contain about 10 ppm to about 1000 ppm of a quaternary ammonium salt, for example, about 10 ppm to about 900 ppm, about 10 ppm to about 500 ppm, about 100 ppm to about 900 ppm, about 100 ppm to about 850 ppm, about 100 ppm to about 800 ppm, about 100 ppm to about 750 ppm, about 100 ppm to about 700 ppm, or about 100 ppm to about It may contain about 650 ppm, about 100 ppm to about 600 ppm, about 100 ppm to about 550 ppm, about 100 ppm to about 500 ppm, about 110 ppm to about 500 ppm, about 120 ppm to about 500 ppm, about 130 ppm to about 500 ppm, about 140 ppm to about 500 ppm, or about 150 ppm to about 500 ppm of a quaternary ammonium salt.

[0030] The chemical-mechanical polishing composition can include one or more compounds (i.e., pH-adjusting compounds) capable of adjusting (i.e., controlling) the pH of the polishing composition. The pH of the polishing composition can be adjusted using any suitable compound capable of adjusting the pH of the polishing composition. The pH-adjusting compound is desirably water-soluble and compatible with the other components of the polishing composition. Typically, the chemical-mechanical polishing composition has a pH of about 5 to about 8 at the point of use. Preferably, the chemical-mechanical polishing composition has a pH of 5 to about 7, for example, a pH of about 5 to about 6, at the point of use.

[0031] The pH-adjusting agent can be virtually any suitable pH-adjusting agent, such as an alkylamine, an alcoholamine, a quaternary amine hydroxide, ammonia, an ammonium salt, an alkali metal salt, a carboxylic acid, an alkali metal hydroxide, an alkali metal carbonate, an alkali metal bicarbonate, a borate, a phosphate, a sulfate, an acetate, a malonate, an oxalate, a borate, an ammonium salt, an azole, an alkylammonium base or conjugate acid, an alkylammonium hydroxide, an ammonium alkoxide or its conjugate acid, a mixture thereof, or the like. In some embodiments, a suitable pH-adjusting agent can include triethanolamine (TEA), tetramethylammonium hydroxide (TMAH or TMA-OH), or tetraethylammonium hydroxide (TEAH or TEA-OH). The polishing composition can include a sufficient concentration of the pH-adjusting agent to achieve and / or maintain the pH of the polishing composition within the pH ranges described above.

[0032] The chemical-mechanical polishing composition optionally further comprises one or more additives. Exemplary additives include conditioners, complexing agents, chelating agents, biocides, rheology modifiers, and dispersants.

[0033] When present, the biocide or fungicide may be any suitable additive having or exhibiting biocidal or fungicidal properties, such as limiting the growth, eliminating the growth, or eliminating any undesirable unicellular or multicellular organisms, or any activity therebetween, and may be present in the polishing composition in any suitable amount. Suitable biocides may include, but are not limited to, isothiazolinones. Typically, the polishing composition contains about 1 ppm to about 100 ppm of biocide, preferably about 10 ppm to about 20 ppm. Suitable fungicides, such as diquaternary ammonium surfactants, may also be used.

[0034] The polishing composition can be produced by any suitable technique, many of which are known to those skilled in the art. The polishing composition can be prepared in a batch process or a continuous process. Generally, the polishing composition is prepared by combining the components of the polishing composition. As used herein, the term "component" includes individual components (e.g., ceria, cationic polymer, quaternary ammonium salt or quaternary phosphonium salt, any pH adjuster, and / or any additives) as well as any combination of components (e.g., ceria, cationic polymer, quaternary ammonium salt or quaternary phosphonium salt, any pH adjuster).

[0035] For example, the polishing composition can be prepared by (i) providing all or a portion of the water; (ii) dispersing the ceria particles, cationic polymer, quaternary ammonium salt or quaternary phosphonium salt, any pH adjuster, and / or any additives using any means suitable for preparing such a dispersion; (iii) adjusting the pH of the dispersion as needed; and (iv) optionally adding suitable amounts of any other optional components and / or mixtures.

[0036] Alternatively, the polishing composition can be prepared by (i) providing one or more components (e.g., water, a cationic polymer, a quaternary ammonium salt or a quaternary phosphonium salt, an optional pH adjuster, and / or any optional additives) in a ceria slurry, (ii) providing one or more components (e.g., water, a cationic polymer, a quaternary ammonium salt or a quaternary phosphonium salt, an optional pH adjuster, and / or any optional additives) in an additive solution, (iii) combining the ceria slurry and the additive solution to form a mixture, (iv) optionally adding suitable amounts of any other optional additives to the mixture, and (v) adjusting the pH of the mixture as needed.

[0037] The polishing composition can be supplied as a one-package system containing ceria particles, a cationic polymer, a quaternary ammonium salt or quaternary phosphonium salt, an optional pH adjuster, and / or any optional additives and water. Alternatively, the polishing composition of the present invention can be supplied as a two-package system containing a ceria slurry and an additive solution, where the ceria slurry consists essentially of or consists of ceria particles, an optional pH adjuster, and water, and the additive solution consists essentially of or consists of a cationic polymer, a quaternary ammonium salt or quaternary phosphonium salt, an optional pH adjuster, and / or any optional additives. The two-package system allows for adjustment of the overall planarization characteristics and polishing rate of the substrate by changing the blending ratio of the two packages, i.e., the ceria slurry and the additive solution.

[0038] Various methods can be used to use such a two-package polishing system. For example, the ceria slurry and the additive solution can be delivered to the polishing table through different pipes that are joined and connected at the outlet of the supply pipe. The ceria slurry and the additive solution can be mixed shortly before or immediately before polishing, or can be supplied simultaneously onto the polishing table. Furthermore, when the two packages are mixed, deionized water can be added as desired to adjust the polishing composition and the resulting substrate polishing characteristics.

[0039] Similarly, three, four, or more package systems can be utilized in connection with the present invention, where each of the multiple containers contains a different component of the inventive chemical-mechanical polishing composition, one or more optional components, and / or one or more of the same components at different concentrations.

[0040] For the purpose of mixing the components stored in two or more storage devices to create a polishing composition at or near the point of use, the storage devices are provided with one or more flow lines leading from each storage device to the point of use of the polishing composition (e.g., a platen, a polishing pad, or a substrate surface). As used herein, the term "point of use" refers to the point at which the polishing composition is applied to the substrate surface (e.g., a polishing pad or the substrate surface itself). The term "flow line" refers to the flow path from an individual storage container to the point of use of the components stored therein. Each flow line can lead directly to the point of use, or two or more flow lines can be combined at any point into a single flow line leading to the point of use. Furthermore, any of the flow lines (e.g., individual flow lines or combined flow lines) can first lead to one or more other devices (e.g., a pumping device, a metering device, a mixing device, etc.) and then reach the point of use of the component.

[0041] The components of the polishing composition can be delivered to the point of use independently (e.g., the components are delivered to the substrate surface, at which point the components are mixed during the polishing process), or one or more components can be combined prior to delivery to the point of use, e.g., shortly before or immediately before delivery to the point of use. The components are combined "immediately before delivery to the point of use" if they are combined within about 5 minutes before application to the platen in mixed form, e.g., within about 4 minutes, within about 3 minutes, within about 2 minutes, within about 1 minute, within about 45 seconds, within about 30 seconds, within about 10 seconds before application to the platen in mixed form, or simultaneously with delivery of the components to the point of use (e.g., the components are combined in a dispenser). Similarly, the components are combined "immediately before delivery to the point of use" if they are combined within 5 meters of the point of use, e.g., within 1 meter of the point of use, or even within 10 cm of the point of use (e.g., within 1 cm of the point of use).

[0042] When two or more components of the polishing composition are combined before reaching the point of use, the components can be combined in a flow line and delivered to the point of use without using a mixing device. Alternatively, one or more of the flow lines can lead into a mixing device to facilitate the combination of two or more components. Any suitable mixing device can be used. For example, the mixing device can be a nozzle or jet (e.g., a high-pressure nozzle or jet) through which two or more components flow. Alternatively, the mixing device can be a container-type mixing device that includes one or more inlets through which two or more components of the polishing slurry are introduced into the mixer and at least one outlet through which the mixed components exit the mixer and are delivered to the point of use directly or via other elements of the apparatus (e.g., via one or more flow lines). Furthermore, the mixing device can include two or more chambers, each with at least one inlet and at least one outlet, where two or more components are combined in each chamber. When a container-type mixing device is used, the mixing device preferably includes a mixing mechanism to further facilitate the combination of the components. Mixing mechanisms are generally known in the art and include stir bars, blenders, agitators, baffles with paddles, gas sparger systems, vibrators, and the like.

[0043] The polishing composition 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 contains the components of the polishing composition in amounts such that, upon dilution of the concentrate 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 listed above for each component. For example, the ceria particles, cationic polymer, quaternary ammonium salt or quaternary phosphonium salt, optional pH adjuster, and / or any optional additives can each be present in the concentrate in an amount about twice (e.g., about three times, about four times, or about five times) the concentration listed above for each component, such that, when the concentrate is diluted with an equal volume of water (e.g., 2 equal volumes of water, 3 equal volumes of water, 4 equal volumes of water, or 5 equal volumes of water, respectively), each component will be present in the polishing composition in an amount within the range specified above for each component. Additionally, as will be understood by those skilled in the art, the concentrate can contain an appropriate proportion of water to be present in the final polishing composition to ensure that the ceria, cationic polymer, quaternary ammonium salt or quaternary phosphonium salt, optional pH adjuster, and / or any optional additives are at least partially or completely dissolved in the concentrate.

[0044] The present invention also provides a method for chemically mechanically polishing a substrate with the polishing composition described herein. Specifically, the present invention provides a method for chemically mechanically polishing a substrate, comprising the steps of: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition having a pH of about 5 to about 8, the chemical mechanical polishing composition comprising: (a) an abrasive containing ceria particles; (b) a cationic polymer selected from a cationic homopolymer, a cationic copolymer containing at least one cationic monomer and at least one nonionic monomer, and combinations thereof; (c) a quaternary ammonium salt or a quaternary phosphonium salt; and (d) water; (iv) contacting the polishing pad and the chemical mechanical polishing composition with the substrate; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade a portion of the surface of the substrate, thereby polishing the substrate.

[0045] The chemical mechanical polishing composition can be used to polish any suitable substrate, and is particularly useful for polishing a substrate that includes at least one layer (typically a surface layer) made of a low-dielectric material. Suitable substrates include wafers used in the semiconductor industry. Wafers typically include or are made of, for example, metals, metal oxides, metal nitrides, metal composites, metal alloys, low-dielectric materials, or combinations thereof. The method of the present invention is particularly useful for polishing substrates that include silicon oxide, silicon nitride, and / or polysilicon, for example, any one, two, or three of these materials.

[0046] In some embodiments, the substrate comprises polysilicon in combination with silicon oxide and / or silicon nitride. The polysilicon can be any suitable polysilicon, many of which are known in the art. It is well known in the art that polysilicon substrates can also contain dopants. Any suitable dopant for polysilicon can be used. Common dopants include, but are not limited to, boron and phosphorus. The polysilicon substrate can have any suitable phase and can be amorphous, crystalline, or a combination thereof. The silicon nitride can similarly be of any suitable type known in the art. Common types can include, but are not limited to, PE or LP. Any ratio of Si to N in the silicon nitride composition can be suitable. Similarly, the silicon oxide can be any suitable silicon oxide, many of which are known in the art. Suitable silicon oxide types include, but are not limited to, TEOS, borophosphosilicate glass (BPSG), PETEOS, thermal oxide, undoped silicate glass, and HDP oxide.

[0047] As is well known in the art, due to the nature of the application of polysilicon and its inherent properties, it may be necessary to prepare the polysilicon thin film before performing the planarization step. Silicon, a hygroscopic and air-sensitive material, forms an oxide passivation layer upon exposure to water or atmospheric oxygen. Depending on the composition and nature of the polysilicon thin film using the embodiments presented herein, a preparatory step to remove this accidental native oxide layer from the polysilicon may be required. Methods for preparing polysilicon are well known in the art and include, but are not limited to: 1) an additional CMP step using a slurry composition with a high oxide ratio; or 2) using an embodiment of the present invention with an increased tool downforce to remove the native oxide and expose a fresh, less oxidized polysilicon surface. Therefore, it is understood that the polishing rates reported herein for polysilicon reflect the polishing rate after the native oxide has been removed.

[0048] The chemical mechanical polishing composition of the present invention desirably exhibits a low removal rate when polishing a substrate containing silicon oxide according to the method of the present invention. For example, when polishing a silicon wafer containing high-density plasma (HDP) oxide and / or plasma-enhanced tetraethyl orthosilicate (PETEOS) and / or tetraethyl orthosilicate (TEOS) according to one embodiment of the present invention, the polishing composition desirably exhibits a silicon oxide removal rate of about 500 Å / min or less, for example, about 400 Å / min or less, about 300 Å / min or less, about 200 Å / min or less, about 100 Å / min or less, about 50 Å / min or less, about 40 Å / min or less, about 30 Å / min or less, about 20 Å / min or less, or about 10 Å / min or less.

[0049] The chemical mechanical polishing composition of the present invention desirably exhibits a high removal rate when polishing a substrate comprising silicon nitride according to the method of the present invention. For example, when polishing a silicon wafer comprising silicon nitride according to one embodiment of the present invention, the polishing composition desirably exhibits a silicon nitride removal rate of about 500 Å / min or more, for example, about 600 Å / min or more, about 700 Å / min or more, about 800 Å / min or more, about 900 Å / min or more, about 1000 Å / min or more, about 1100 Å / min or more, about 1200 Å / min or more, about 1300 Å / min or more, about 1400 Å / min or more, or about 1500 Å / min or more.

[0050] The chemical mechanical polishing composition of the present invention desirably exhibits a high removal rate when polishing a substrate containing polysilicon according to the method of the present invention. For example, when polishing a silicon wafer containing polysilicon according to one embodiment of the present invention, the polishing composition desirably exhibits a polysilicon removal rate of about 500 Å / min or more, for example, about 600 Å / min or more, about 700 Å / min or more, about 800 Å / min or more, about 900 Å / min or more, about 1000 Å / min or more, about 1100 Å / min or more, about 1200 Å / min or more, about 1300 Å / min or more, about 1400 Å / min or more, or about 1500 Å / min or more.

[0051] In some embodiments, the substrate comprises silicon nitride on a surface of the substrate, and at least a portion of the silicon nitride on the surface of the substrate is ground away at a removal rate to polish the substrate, and the substrate further comprises silicon oxide on its surface, in these embodiments, at least a portion of the silicon oxide on the surface of the substrate is ground away at a removal rate to polish the substrate, wherein the silicon oxide removal rate is lower than the silicon nitride removal rate.

[0052] In other embodiments, the substrate comprises polysilicon on the surface of the substrate, and at least a portion of the polysilicon on the surface of the substrate is ground away at any removal rate to polish the substrate, and the substrate further comprises silicon oxide on its surface. In these embodiments, at least a portion of the silicon oxide on the surface of the substrate is ground away at any removal rate to polish the substrate, wherein the silicon oxide removal rate is lower than the polysilicon removal rate.

[0053] Although not wanting to be bound by any particular theory, it is believed that cationic polymers are preferentially adsorbed onto the surface of silicon oxide.It is believed that cationic polymers form a protective film on the silicon oxide surface, preventing contact between the polishing composition and the silicon oxide surface, thereby reducing the silicon oxide removal rate, while advantageously not significantly affecting the silicon nitride removal rate.The addition of quaternary ammonium salt improves the coverage of the silicon oxide surface, thereby improving the stopping ability of silicon oxide, thereby significantly reducing or preventing the removal of silicon oxide.In addition, quaternary ammonium salt or quaternary phosphonium salt functions to distribute cationic polymers in the solution, thereby making more cationic polymers available for the surface of the pad / wafer.

[0054] The chemical mechanical polishing composition and method of the present invention are particularly suitable for use with a chemical mechanical polishing apparatus. Typically, the apparatus includes a platen that is in motion during use and has a velocity resulting from orbital, linear, or circular motion, a polishing pad that contacts the platen and moves with the platen during motion, and a carrier that holds the substrate to be polished by contacting and moving the substrate relative to the surface of the polishing pad. Polishing of the substrate is performed by placing the substrate in contact with the polishing pad and 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.

[0055] Any suitable polishing pad (e.g., polishing surface) can be used to polish a substrate with a chemical-mechanical polishing composition. Suitable polishing pads include, for example, woven and nonwoven polishing pads. Furthermore, suitable polishing pads can include any suitable polymer with varying density, hardness, thickness, compressibility, rebound capacity upon compression, and compression coefficient. Suitable polymers include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbon, polycarbonate, polyester, polyacrylate, polyether, polyethylene, polyamide, polyurethane, polystyrene, polypropylene, co-molded products thereof, and mixtures thereof. Soft polyurethane polishing pads are extremely useful in conjunction with the inventive polishing method. Exemplary pads include, but are not limited to, EPICD100, NexPlanar Element series, NexPlanar Ultra series, Ikonic3000, Visionpad5000, and IC1010. Preferred polishing pads include NexPlanar E6088 and NexPlanar U5050 pads available from Cabot Microelectronics.

[0056] Preferably, the chemical mechanical polishing apparatus further includes 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. Pat. Nos. 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, inspecting or monitoring the progress of the polishing process relative to the substrate being polished allows for the determination of the polishing endpoint, i.e., when to terminate the polishing process for a particular substrate.

[0057] The present invention can be characterized by the following embodiments.

[0058] (1) In the first embodiment, (a) an abrasive comprising ceria particles; (b) a cationic polymer selected from a cationic homopolymer, a cationic copolymer comprising at least one cationic monomer and at least one nonionic monomer, and combinations thereof; (c) a quaternary ammonium salt or a quaternary phosphonium salt; (d) water; In a chemical mechanical polishing composition containing the above, the polishing composition has a pH of about 5 to about 8.

[0059] (2) In embodiment 2, the polishing composition of embodiment (1) is provided, comprising about 0.01 wt % to about 1 wt % ceria particles.

[0060] (3) In embodiment 3, there is provided the polishing composition according to embodiment (1) or (2), wherein the ceria particles have an average particle size of about 60 nm to about 120 nm.

[0061] (4) In embodiment (4), the polishing composition according to any one of embodiments (1) to (3) is provided, which comprises a cationic homopolymer, and comprises about 1 ppm to about 200 ppm of the cationic homopolymer.

[0062] (5) In embodiment (5), the polishing composition according to embodiment (4) is provided, in which the cationic homopolymer can be any suitable cationic homopolymer essentially composed of cationic monomer repeat units. For example, the cationic homopolymer can be any suitable cationic monomer essentially composed of quaternary amine groups as repeat units. The quaternized amine group is acyclic or incorporated into a cyclic structure. The quaternized amine group contains a tetrasubstituted nitrogen atom substituted with four groups independently selected from alkyl, alkenyl, aryl, arylalkyl, acrylamide, or methacrylate groups, or, when incorporated into a cyclic structure, contains either a heterocyclic saturated ring containing a nitrogen atom and further substituted with two groups as described above, or an N-heterocyclic group (e.g., imidazole or pyridine) having an additional group bonded to the nitrogen atom as described above. The quaternized amine group has a positive charge (i.e., a cation with an anionic moiety attached, thereby forming a salt). Similarly, it may be suitable to further modify the cationic polymers by alkylation, acylation, ethoxylation, or other chemical reactions to alter the solubility, viscosity, or other physical parameters of the cationic polymer. Suitable quaternary amine monomers include, for example, quaternized vinylimidazole (vinylimidazolium), methacryloyloxyethyltrimethylammonium (MADQUAT), diallyldimethylammonium (DADMAC), methacrylamidopropyltrimethylammonium (MAPTAC), epichlorohydrin-dimethylamine (epi-DMA), and combinations thereof. Suitable cationic polymers include, for example, quaternized poly(vinylimidazole) methyl sulfate, poly(methacryloyloxyethyltrimethylammonium) chloride (polyMADQUAT), poly(diallyldimethylammonium) chloride (polyDADMAC), poly(dimethylamine-co-epichlorohydrin), poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] (i.e., polyquaternium-2), and combinations thereof.

[0063] (6) In embodiment (6), the polishing composition according to any one of embodiments (1) to (3) is provided, which comprises a cationic copolymer, and the cationic copolymer is present in an amount of about 1 ppm to about 1000 ppm.

[0064] (7) In embodiment (7), the polishing composition of embodiment (6) is provided, wherein the cationic copolymer comprises at least one cationic monomer and at least one nonionic monomer, and the at least one cationic monomer comprises either more than 50% copolymer on a molar basis or about 50% or less copolymer on a molar basis. The cationic monomer can be as described herein in connection with the cationic homopolymer. Non-limiting examples of suitable nonionic monomers include vinylpyrrolidone, vinylcaprolactam, vinylimidazole, acrylamide, vinyl alcohol, polyvinyl formal, polyvinyl butyral, poly(vinyl phenyl ketone), vinylpyridine, polyacrolein, ethylene, propylene, styrene, and combinations thereof. Suitable cationic copolymers include, for example, copolymers of acrylamide and diallyldimethylammonium (i.e., Polyquaternium-7), copolymers of vinylpyrrolidone and quaternized dimethylaminoethyl methacrylate (i.e., Polyquaternium-11), copolymers of vinylpyrrolidone and quaternized vinylimidazole (i.e., Polyquaternium-16), terpolymers of vinylcaprolactam, vinylpyrrolidone, and quaternized vinylimidazole (i.e., Polyquaternium-46), and 3-methyl-1-vinylimidazolium methylsulfate-N-vinylpyrrolidone copolymer (i.e., Polyquaternium-44), copolymers of vinylpyrrolidone and diallyldimethylammonium. Further suitable cationic polymers include personal care cationic polymers such as Luviquat® Supreme, Luviquat® Hold, Luviquat® UltraCare, Luviquat® FC370, Luviquat® FC550, Luviquat® FC552, and Luviquat® Excellence.

[0065] (8) In embodiment (8), the polishing composition according to any one of embodiments (1) to (7) is provided, wherein the polishing composition further comprises a quaternary ammonium salt, the quaternary ammonium being a halide containing a quaternary ammonium cation having a molecular weight of about 75 g / mol or greater. Non-limiting examples of suitable quaternary ammonium salts include tetramethylammonium salts, tetraethylammonium salts, tetrapropylammonium salts, tetrabutylammonium salts, tetrapentylammonium salts, tetrahexylammonium salts, tetraheptylammonium salts, tetraoctylammonium salts, tetradodecylammonium salts, diallyldimethylammonium salts and derivatives, benzalkonium salts, N-alkylmethylimidazolium salts, N,N-diarylimidazolium salts, N-alkylpyridinium salts, didecyldimethylammonium salts, tetrabenzylammonium salts, benzyldimethyldecylammonium salts, benzyldimethylhexylammonium salts, benzyldimethyloctylammonium salts, benzyldodecyldimethylammonium salts, benzyltributylammonium salts, benzyltriethylammonium salts, and benzyl Trimethylammonium salt, decyltrimethylammonium salt, didodecyldimethylammonium salt, dodecylethyldimethylammonium salt, dodecyltrimethylammonium salt, hexyltrimethylammonium salt, methyltrioctylammonium salt, tributylmethylammonium salt, tridodecylmethylammonium salt, triethylhexylammonium salt, triethylmethylammonium salt, trimethyloctylammonium salt, trimethylphenylammonium salt, trihexyltetradecylammonium salt, [(3-methacryloylamino)propyl]trimethylammonium salt, (3-acrylamidopropyl)trimethylammonium salt, 2-(acryloyloxy)ethyltrimethylammonium salt, (vinylbenzyl)trimethylammonium salt, choline salt, and tris(2-hydroxyethyl)methylammonium salt.

[0066] (9) In embodiment (9), the polishing composition according to any one of embodiments (1) to (7) is provided, which contains a quaternary ammonium salt, and contains about 10 ppm to about 1000 ppm of the quaternary ammonium salt.

[0067] (10) In embodiment (10), the polishing composition according to any one of embodiments (1) to (7) is provided, further comprising a quaternary phosphonium salt, wherein the quaternary phosphonium salt is a halide containing a quaternary phosphonium cation having a molecular weight of about 94 g / mol or greater. Non-limiting examples of suitable quaternary phosphonium salts include benzyltriphenylphosphonium salt, dimethyldiphenylphosphonium salt, tetrabutylphosphonium salt, tetramethylphosphonium salt, tetraphenylphosphonium salt, tetrapropylphosphonium salt, tetraoctylphosphonium salt, butyltriphenylphosphonium salt, tetraethylphosphonium salt, tributyldodecylphosphonium salt, ethyltriphenylphosphonium salt, hexyltriphenylphosphonium salt, heptyltriphenylphosphonium salt, isopropyltriphenylphosphonium salt, methyltriphenylphosphonium salt, tributylmethylphosphonium salt, tributyloctylphosphonium salt, triphenylpropylphosphonium salt, and tributylhexylphosphonium salt.

[0068] (11) In embodiment (11), the polishing composition according to any one of embodiments (1) to (7) is provided, which contains a quaternary phosphonium salt, and the polishing composition contains about 10 ppm to about 1000 ppm of the quaternary phosphonium salt.

[0069] (12) In embodiment (12), a method for chemically mechanically polishing a substrate includes: (i) providing a substrate; (ii) providing a polishing pad; (iii)(a) an abrasive comprising ceria particles; (b) a cationic polymer selected from a cationic homopolymer, a cationic copolymer comprising at least one cationic monomer and at least one nonionic monomer, and combinations thereof; (c) a quaternary ammonium salt or a quaternary phosphonium salt; (d) water; providing a chemical-mechanical polishing composition comprising: (iv) contacting the substrate with a polishing pad and a chemical-mechanical polishing composition; (v) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to abrade a portion of the surface of the substrate, thereby polishing the substrate; A method is presented, including:

[0070] (13) In embodiment (13), the method of embodiment (12) is provided, wherein the polishing composition comprises about 0.01 wt. % to about 1 wt. % ceria particles.

[0071] (14) In embodiment (14), the method of embodiment (12) or (13) is provided, wherein the ceria particles have an average particle size of about 60 nm to about 120 nm.

[0072] (15) In embodiment (15), the method of any one of embodiments (12) to (14) is provided, wherein the polishing composition comprises a cationic homopolymer and comprises about 1 ppm to about 200 ppm of the cationic homopolymer.

[0073] (16) In embodiment (16), the method of embodiment (15) is provided, in which the cationic homopolymer can be any suitable cationic homopolymer consisting essentially of cationic monomer repeat units. For example, the cationic homopolymer can be any suitable cationic monomer consisting essentially of quaternary amine groups as repeat units. The quaternized amine groups are acyclic or incorporated into a cyclic structure. The quaternized amine groups include a tetrasubstituted nitrogen atom substituted with four groups independently selected from alkyl, alkenyl, aryl, arylalkyl, acrylamide, or methacrylate groups; or, when incorporated into a cyclic structure, a heterocyclic saturated ring containing the nitrogen atom and further substituted with two groups as described above, or an N-heterocyclic group (e.g., imidazole or pyridine) having an additional group bonded to the nitrogen atom as described above. The quaternized amine group is positively charged (i.e., a cation with an anionic moiety attached thereto, thereby forming a salt). Similarly, it may be suitable to further modify the cationic polymers by alkylation, acylation, ethoxylation, or other chemical reactions to alter the solubility, viscosity, or other physical parameters of the cationic polymer. Suitable quaternary amine monomers include, for example, quaternized vinylimidazole (vinylimidazolium), methacryloyloxyethyltrimethylammonium (MADQUAT), diallyldimethylammonium (DADMAC), methacrylamidopropyltrimethylammonium (MAPTAC), epichlorohydrin-dimethylamine (epi-DMA), and combinations thereof. Suitable cationic polymers include, for example, quaternized poly(vinylimidazole) methyl sulfate, poly(methacryloyloxyethyltrimethylammonium) chloride (polyMADQUAT), poly(diallyldimethylammonium) chloride (polyDADMAC), poly(dimethylamine-co-epichlorohydrin), poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] (i.e., polyquaternium-2), and combinations thereof.

[0074] (17) In embodiment (17), the method of any one of embodiments (12) to (14) is provided, wherein the polishing composition comprises a cationic copolymer and comprises from about 1 ppm to about 1000 ppm of the cationic copolymer.

[0075] (18) In embodiment (18), the method of embodiment (17) is provided, wherein the cationic copolymer comprises at least one cationic monomer and at least one nonionic monomer, and the at least one cationic monomer comprises either more than 50% copolymer on a molar basis or about 50% or less copolymer on a molar basis. The cationic monomer can be as described herein with respect to the cationic homopolymer. Non-limiting examples of suitable nonionic monomers include vinylpyrrolidone, vinylcaprolactam, vinylimidazole, acrylamide, vinyl alcohol, polyvinyl formal, polyvinyl butyral, poly(vinyl phenyl ketone), vinylpyridine, polyacrolein, ethylene, propylene, styrene, and combinations thereof. Suitable cationic copolymers include, for example, copolymers of acrylamide and diallyldimethylammonium (i.e., Polyquaternium-7), copolymers of vinylpyrrolidone and quaternized dimethylaminoethyl methacrylate (i.e., Polyquaternium-11), copolymers of vinylpyrrolidone and quaternized vinylimidazole (i.e., Polyquaternium-16), terpolymers of vinylcaprolactam, vinylpyrrolidone, and quaternized vinylimidazole (i.e., Polyquaternium-46), and 3-methyl-1-vinylimidazolium methylsulfate-N-vinylpyrrolidone copolymer (i.e., Polyquaternium-44), copolymers of vinylpyrrolidone and diallyldimethylammonium. Further suitable cationic polymers include personal care cationic polymers such as Luviquat® Supreme, Luviquat® Hold, Luviquat® UltraCare, Luviquat® FC370, Luviquat® FC550, Luviquat® FC552, and Luviquat® Excellence.

[0076] (19) In embodiment (19), the polishing composition is a method according to any one of embodiments (12) to (18), wherein the polishing composition comprises a quaternary ammonium salt, the quaternary ammonium being a halide containing a quaternary ammonium cation having a molecular weight of about 75 g / mol or greater. Non-limiting examples of suitable quaternary ammonium salts include tetramethylammonium salts, tetraethylammonium salts, tetrapropylammonium salts, tetrabutylammonium salts, tetrapentylammonium salts, tetrahexylammonium salts, tetraheptylammonium salts, tetraoctylammonium salts, tetradodecylammonium salts, diallyldimethylammonium salts and derivatives, benzalkonium salts, N-alkylmethylimidazolium salts, N,N-diarylimidazolium salts, N-alkylpyridinium salts, didecyldimethylammonium salts, tetrabenzylammonium salts, benzyldimethyldecylammonium salts, benzyldimethylhexylammonium salts, benzyldimethyloctylammonium salts, benzyldodecyldimethylammonium salts, benzyltributylammonium salts, benzyltriethylammonium salts, and benzyl Trimethylammonium salt, decyltrimethylammonium salt, didodecyldimethylammonium salt, dodecylethyldimethylammonium salt, dodecyltrimethylammonium salt, hexyltrimethylammonium salt, methyltrioctylammonium salt, tributylmethylammonium salt, tridodecylmethylammonium salt, triethylhexylammonium salt, triethylmethylammonium salt, trimethyloctylammonium salt, trimethylphenylammonium salt, trihexyltetradecylammonium salt, [(3-methacryloylamino)propyl]trimethylammonium salt, (3-acrylamidopropyl)trimethylammonium salt, 2-(acryloyloxy)ethyltrimethylammonium salt, (vinylbenzyl)trimethylammonium salt, choline salt, and tris(2-hydroxyethyl)methylammonium salt.

[0077] (20) In embodiment (20), the method of any one of embodiments (12) to (18) is presented, wherein the polishing composition comprises a quaternary ammonium salt and comprises about 10 ppm to about 1000 ppm of the quaternary ammonium salt.

[0078] (21) In embodiment (21), the polishing composition according to any one of embodiments (12) to (18) is provided, wherein the polishing composition comprises a quaternary phosphonium salt, and the quaternary phosphonium salt is a halide containing a quaternary phosphonium cation having a molecular weight of about 94 g / mol or greater. Non-limiting examples of suitable quaternary phosphonium salts include benzyltriphenylphosphonium salt, dimethyldiphenylphosphonium salt, tetrabutylphosphonium salt, tetramethylphosphonium salt, tetraphenylphosphonium salt, tetrapropylphosphonium salt, tetraoctylphosphonium salt, butyltriphenylphosphonium salt, tetraethylphosphonium salt, tributyldodecylphosphonium salt, ethyltriphenylphosphonium salt, hexyltriphenylphosphonium salt, heptyltriphenylphosphonium salt, isopropyltriphenylphosphonium salt, methyltriphenylphosphonium salt, tributylmethylphosphonium salt, tributyloctylphosphonium salt, triphenylpropylphosphonium salt, tributylhexylphosphonium salt, and the like.

[0079] (22) In embodiment (22), the method of any one of embodiments (12) to (18) is provided, wherein the polishing composition comprises a quaternary phosphonium salt and comprises about 10 ppm to about 1000 ppm of the quaternary phosphonium salt.

[0080] (23) In embodiment (23), there is provided a method according to any one of embodiments (12) to (22), wherein the substrate comprises silicon nitride on a surface thereof, and at least a portion of the silicon nitride on the surface of the substrate is ground away at any removal rate to polish the substrate.

[0081] (24) In embodiment (24), the method of embodiment (23) is provided, wherein the substrate further comprises silicon oxide on its surface, and at least a portion of the silicon oxide on the surface of the substrate is ground away at a removal rate such that the substrate is polished, and the silicon oxide removal rate is lower than the silicon nitride removal rate.

[0082] (25) In embodiment (25), the method of any one of embodiments (12) to (22) is provided, wherein a substrate includes polysilicon on a surface thereof, and at least a portion of the polysilicon on the surface of the substrate is ground at any removal rate to polish the substrate.

[0083] (26) In embodiment (26), the method of embodiment (25) is provided, wherein the substrate further comprises silicon oxide on its surface, and at least a portion of the silicon oxide on the surface of the substrate is ground away at a removal rate such that the substrate is polished, and the silicon oxide removal rate is lower than the polysilicon removal rate.

[0084] The following examples further illustrate the present invention but should not be construed as in any way limiting its scope. [Example]

[0085] Example 1 This example demonstrates the effect of ceria particle size on the removal rate of SiN and SiO, in accordance with one embodiment of the present invention.

[0086] Substrates containing SiN and SiO layers were polished separately with Polishing Composition 1A and Polishing Composition 1B. Polishing Composition 1A contained 0.2 wt. % ceria with an average particle size of 60 nm and 30 ppm polyMADQUAT (poly(2-methacryloyloxyethyltrimethylammonium chloride) (i.e., a cationic homopolymer) at a pH of 5.3. Polishing Composition 1B contained 0.2 wt. % ceria with an average particle size of 90-110 nm and 30 ppm polyMADQUAT at a pH of 5.3. The polishing conditions were as follows: rotation (platen), 113 rpm; rotation (carrier), 107 rpm; slurry flow rate, 250 mL / min; downforce, 3 psi (20.7 kPa); polishing time, 60 seconds.

[0087] After polishing, the removal rates of SiN and SiO were determined and the results are listed in Table 1. The SiN / SiO selectivity is the ratio of the SiN removal rate to the SiO removal rate.

[0088] [Table 1]

[0089] As is evident from the results shown in Table 1, Polishing Composition 1B, which contained ceria with an average particle size of 90-110 nm, exhibited SiN and SiO removal rates that were approximately 269% and 677% greater than the SiN and SiO removal rates exhibited by Polishing Composition 1A, which contained ceria with an average particle size of 60 nm. Both Polishing Compositions 1A and 1B exhibited desirable SiN / SiO selectivities, with Polishing Composition 1B exhibiting a SiN / SiO selectivity that was approximately 47% of the SiN / SiO selectivity exhibited by Polishing Composition 1A.

[0090] Example 2 This example demonstrates the effect of cationic homopolymer and cationic copolymer concentrations on the SiN and SiO removal rates of polishing compositions containing these cationic homopolymers and cationic copolymers at pH 5.0 according to one embodiment of the present invention.

[0091] Substrates containing SiN or SiO layers were separately polished with Polishing Compositions 2A-2E. Polishing Compositions 2A-2E contained 0.2 wt. % ceria with an average particle size of 60 nm in water at pH 5.0, 30 ppm acetate buffer, and a biocide. Polishing Composition 2A (control) did not contain any additional components. Polishing Compositions 2B and 2C further contained 30 ppm or 150 ppm of polyDADMAC homopolymer, respectively. Polishing Compositions 2D and 2E further contained 30 ppm or 150 ppm of polyDADMAC copolymer with acrylamide, respectively. The polishing conditions were as follows: rotation (platen), 100 rpm; rotation (carrier), 85 rpm; slurry flow rate, 150 mL / min; downforce, 2.5 psi (17.2 kPa); SiN polishing time, 40 seconds; SiO polishing time, 120 seconds.

[0092] After polishing, the SiN and SiO removal rates were determined and the results are listed in Table 2.

[0093] [Table 2]

[0094] As is evident from the results reported in Table 2, increasing the concentration of polyDADMAC cationic homopolymer from 30 ppm in Polishing Composition 2B to 150 ppm in Polishing Composition 2C resulted in an approximately 59% decrease in the SiN removal rate and an approximately 50% decrease in the SiO removal rate. Increasing the concentration of polyDADMAC cationic copolymer from 30 ppm in Polishing Composition 2D to 150 ppm in Polishing Composition 2E resulted in an insignificant decrease in the SiN removal rate, but an approximately 85% decrease in the SiO removal rate, resulting in an improvement in SiN / SiO selectivity from 0.61 to 3.8. Thus, increasing the concentration of polyDADMAC cationic copolymer improved SiN / SiO selectivity without significantly affecting the SiN removal rate, and significantly decreased the SiO removal rate, thereby maintaining favorable SiN / SiO selectivity.

[0095] Example 3 This example demonstrates the effect of a particular cationic polymer on the SiN and SiO removal rates of a polishing composition containing the polymer at pH 7.

[0096] Substrates containing SiN or SiO layers were separately polished with Polishing Compositions 3A-3F. Polishing Compositions 3A-3F contained 0.4 wt. % ceria with an average particle size of 90-110 nm and 40 ppm triethanolamine buffer in water at pH 7. Polishing Composition 3A (control) did not contain any additional components. Polishing Composition 3B further contained 25 ppm DADMAC vinylpyrrolidone copolymer containing 30% DADMA (monomer). Polishing Composition 3C further contained 25 ppm DADMAC vinylpyrrolidone copolymer containing 50% DADMAC monomer. Polishing Composition 3C further contained 25 ppm DADMAC homopolymer. Polishing Composition 3E further contained 25 ppm quaternized vinylimidazole-vinylpyrrolidone copolymer containing 30% quaternized vinylimidazole monomer. Polishing Composition 3F further contained 25 ppm of quaternized poly(vinylimidazole) homopolymer. The polishing conditions were as follows: rotation (platen), 90 rpm; rotation (carrier), 93 rpm; slurry flow rate, 150 mL / min; down force, 3 psi (20.7 kPa); SiN and SiO polishing time, 60 seconds.

[0097] After polishing, the SiN and SiO removal rates were determined and the results are listed in Table 3.

[0098] [Table 3]

[0099] As is evident from the results reported in Table 3, as the percentage of cationic monomer units in the cationic polymer increased from 30% to 50% to 100% in Polishing Compositions 3B to 3D, the SiN removal rate decreased from 856 Å / min to 692 Å / min, and the SiN / SiO selectivity increased from 0.2 to 36. By increasing the percentage of cationic monomer units from 30% to 50% in Polishing Compositions 3E and 3F, which contained cationic polymers containing quaternized poly(vinylimidazole) monomer units, the SiN removal rate increased by approximately 18%, and the SiN / SiO selectivity increased by approximately 66-fold.

[0100] Example 4 This example demonstrates the effect of the concentration of a cationic polymer and a quaternary ammonium salt on the SiN and SiO removal rates of a polishing composition including this combination according to one embodiment of the present invention.

[0101] Substrates containing SiN or SiO layers were polished separately with Polishing Compositions 4A and 4B. Polishing Compositions 4A and 4B contained 0.2 wt. % ceria with an average particle size of 60 nm, quaternized poly(vinylimidazole) (i.e., a cationic homopolymer) and diallyldimethylammonium chloride monomer (DADDAC) (i.e., a quaternary ammonium salt) in the amounts listed in Table 4, 30 ppm acetate buffer, and a biocide in water at a pH of 5.3. The polishing conditions were as follows: rotation (platen), 113 rpm; rotation (carrier), 107 rpm; slurry flow rate, 150 mL / min; downforce, 3 psi (20.7 kPa); and polishing time for SiN and SiO, 60 seconds.

[0102] After polishing, the SiN and SiO removal rates were determined and the results are listed in Table 4.

[0103] [Table 4]

[0104] As is evident from the results reported in Table 4, increasing the concentrations of quaternized poly(vinylimidazole) and DADMAC monomer from 10 ppm and 50 ppm to 50 ppm and 550 ppm, respectively, resulted in a desirable increase in the SiN removal rate of approximately 400% and a decrease in the SiO removal rate of approximately 86%. The resulting increase in SiN / SiO selectivity was approximately 29-fold.

[0105] Example 5 This example demonstrates the effect of a quaternary ammonium salt on the removal rates of SiN and SiO of a polishing composition comprising the salt according to one embodiment of the present invention.

[0106] Substrates containing SiN or SiO layers were polished separately with Polishing Compositions 5A and 5B. Polishing Compositions 5A and 5B contained 0.4 wt. % ceria with an average particle size of 90-110 nm, 52 ppm quaternized poly(vinylimidazole), 650 ppm triethanolamine buffer, and a biocide in water at pH 7. Polishing Composition 5A did not contain a quaternary ammonium salt. Polishing Composition 5B further contained 500 ppm DADMAC monomer (i.e., a quaternary ammonium salt). The polishing conditions were as follows: rotation (platen), 90 rpm; rotation (carrier), 93 rpm; slurry flow rate, 250 mL / min; and polishing time for SiN and SiO, 60 seconds.

[0107] After polishing, the SiN and SiO removal rates were determined and the results are listed in Table 5.

[0108] [Table 5]

[0109] As is evident from the results reported in Table 5, Polishing Composition 5B, which contained 500 ppm DADMAC monomer, exhibited a SiN removal rate that was approximately 11% higher than the SiN removal rate of Polishing Composition 5A, which did not contain DADMAC monomer. The SiO removal rate of Polishing Composition 5B was approximately 50% of the SiO removal rate of Polishing Composition 5A. Thus, the presence of DADMAC monomer effectively suppressed the SiO removal rate of Polishing Composition 5B without interfering with the SiN removal rate, resulting in a desirable increase in selectivity.

[0110] Example 6 This example demonstrates the effect of a cationic polymer and a quaternary ammonium salt combination on the SiN and SiO removal rates of a polishing composition containing this combination.

[0111] Substrates containing SiN or SiO layers were separately polished with Polishing Compositions 6A-6D. Polishing Compositions 6A-6D contained 0.4 wt. % ceria with an average particle size of 90-110 nm and 16.26 ppm triethanolamine buffer in water at pH 7. Polishing Composition 6A (control) did not contain any additional components. Polishing Composition 6B (comparative) further contained 100 ppm DADMAC monomer (i.e., a quaternary ammonium salt). Polishing Composition 6C (comparative) further contained 10 ppm quaternized poly(vinylimidazole) (i.e., a cationic polymer). Polishing Composition 6D (invention) further contained 10 ppm quaternized poly(vinylimidazole) and 100 ppm DADMAC monomer. The polishing conditions were as follows: rotation (platen), 93 rpm; rotation (carrier), 87 rpm; slurry flow rate, 50 mL / min; down force, 2 psi (13.8 kPa); polishing time for SiN and SiO, 60 seconds.

[0112] After polishing, the SiN and SiO removal rates were determined and the results are listed in Table 6.

[0113] [Table 6]

[0114] As is evident from the results reported in Table 6, Polishing Composition 6B, which contained 100 ppm of DADMAC monomer but no quaternized poly(vinylimidazole), exhibited substantially the same SiN / SiO selectivity as the control Polishing Composition 6A, which contained no DADMAC monomer or quaternized poly(vinylimidazole). Polishing Composition 6C, which contained 10 ppm of quaternized poly(vinylimidazole) but no DADMAC monomer, exhibited an SiN removal rate that was approximately 236% higher than the SiN removal rate exhibited by the control Polishing Composition 6A, and an SiO removal rate that was approximately 90% lower than the SiO removal rate exhibited by the control Polishing Composition 6A. Polishing Composition 6D, containing 10 ppm quaternized poly(vinylimidazole) and 100 ppm DADMAC monomer, exhibited a SiN removal rate that was approximately 121% higher than the SiN removal rate exhibited by control Polishing Composition 6A, and an SiO removal rate that was approximately 99% lower than the SiO removal rate exhibited by control Polishing Composition 6A. Thus, the presence of 10 ppm quaternized poly(vinylimidazole) and 100 ppm DADMAC monomer in Polishing Composition 6D desirably suppressed the SiO removal rate without significantly affecting the SiN removal rate compared to Polishing Composition 6C, and substantially improved selectivity compared to control Polishing Composition 6A and comparative Polishing Compositions 6B and 6C.

[0115] Example 7 This example demonstrates the effect of the number of carbon atoms in the quaternary ammonium salt on the SiN and SiO removal rates.

[0116] Substrates containing SiN or SiO layers were separately polished with Polishing Compositions 7A to 7K. Polishing Compositions 7A to 7K each contained 0.2 wt. % ceria with an average particle size of 90 to 110 nm, 3.33 ppm quaternized poly(vinylimidazole), 30 ppm acetic acid buffer, and 1 mM quaternary ammonium salt as shown in Table 7, in water at a pH of about 5.0. The polishing conditions were as follows: rotation (platen), 93 rpm; rotation (carrier), 87 rpm; slurry flow rate, 50 mL / min; down force, 2 psi (13.8 kPa); SiN and SiO polishing time, 60 seconds.

[0117] After polishing, the SiN and SiO removal rates were determined and the results are reported in Table 7.

[0118] [Table 7]

[0119] As is evident from the results shown in Table 7, Polishing Compositions 7A-7C, which did not contain a quaternary ammonium salt, exhibited high SiO removal rates and low SiN / SiO selectivities. Polishing Compositions 7D-7I, which contained quaternary ammonium salts having 4 to 16 carbon atoms, exhibited SiO removal rates that were approximately 34-61% of the control Polishing Composition 7A, while maintaining SiN removal rates that were approximately 91-108% of the SiN removal rate of Polishing Composition 7A. Polishing Compositions 7J and 7K, which contained quaternary ammonium salts having 17 and 27 carbon atoms, respectively, exhibited SiO removal rates that were approximately 15% and 7% of the SiN removal rate of Polishing Composition 7A. The SiN removal rates of Polishing Compositions 7J and 7K were approximately 71% and 55%, respectively, of the SiN removal rate of Polishing Composition 7A, demonstrating a moderate SiN removal rate suppression with quaternary ammonium salts having carbon numbers greater than about 16, which correlates with the hydrophobicity and / or increased size of the alkyl substituents.

[0120] Example 8 This example demonstrates the effect of quaternary phosphonium salts and quaternary ammonium salts on the polishing rate for substrates containing SiN or SiO.

[0121] Substrates containing SiN or SiO layers were polished separately with Polishing Compositions 8A-8F. Each of Polishing Compositions 8A-8F contained 0.2 wt. % ceria with an average particle size of 90-110 nm, 3.33 ppm quaternized poly(vinylimidazole), and 30 ppm acetate buffer in water at a pH of approximately 5.0. Polishing Compositions 8A-8F also contained tetrabutylammonium chloride (BuNCl), tetrabutylammonium bromide (BuNBr), or tetrabutylphosphonium bromide (BuPBr) in the amounts listed in Table 8. The polishing conditions were as follows: rotation (platen), 93 rpm; rotation (carrier), 87 rpm; slurry flow rate, 50 mL / min; downforce, 2 psi (13.8 kPa); and SiN and SiO polishing time, 60 seconds.

[0122] After polishing, the SiN and SiO removal rates were determined and the results are reported in Table 8.

[0123] [Table 8]

[0124] As can be seen from the results in Table 8, increasing the amount of Bu4NCl, Bu4NBr, and Bu4PBr from 1 mM to 5 mM resulted in a relatively small change in SiN removal rate (0-15%), but a decrease in SiO removal rate to 22%, 52%, and 45% of the SiO removal rate exhibited by the polishing composition containing 1 mM of a quaternary ammonium or quaternary phosphonium salt. The SiN / SiO selectivity increased with increasing amounts of Bu4NCl, Bu4NBr, and Bu4PBr due to the suppression of SiO removal rate.

[0125] All references, including publications, patent applications, and patents, cited in this specification are herein incorporated by reference to the same extent as if each reference was individually or specifically indicated to be incorporated by reference and was set forth in its entirety herein.

[0126] Example 9 This example demonstrates the effect of a quaternary ammonium salt on the removal rate of a polishing composition with cubic ceria particles, in accordance with one embodiment of the present invention, including SiN, SiO, and polysilicon.

[0127] Substrates containing SiN, SiO, and polysilicon layers were separately polished with Polishing Compositions 9A-9C. Each of Polishing Compositions 9A-9C had a nitrogen adsorption of 11.8 m per gram. 2 The polishing compositions contained 0.2 wt. % cubic ceria having a BET specific surface area determined by HPLC and an average particle size of 102 nm as measured by a Horiba 960 and 140 nm as measured by a Malvern Zetasizen. Each polishing composition also contained 30 ppm quaternized poly(vinylimidazole) in water. Polishing Compositions 9A and 9B further contained a 0.5 mM acetate buffer at a pH of about 5, and Polishing Composition 9C further contained a 0.5 mM triethanolamine buffer at a pH of about 7. Polishing Composition 9A did not contain a quaternary ammonium salt. Polishing Compositions 9B and 9C further contained 300 ppm diallyldimethylammonium chloride monomer (DADMAC) (i.e., a quaternary ammonium salt). The polishing conditions were as follows: rotation (platen), 113 rpm; rotation (carrier), 107 rpm; slurry flow rate, 150 mL / min; down force, 3 psi (20.7 kPa); polishing time for SiN, SiO, and polysilicon, 60 seconds.

[0128] After polishing, the removal rates of SiN, SiO, and polysilicon were determined and the results are listed in Table 9.

[0129] [Table 9]

[0130] As is evident from the results reported in Table 9, Polishing Compositions 9B and 9C, which contained 300 ppm DADMAC monomer, exhibited SiO removal rates that were approximately 79% and 85%, respectively, lower than Polishing Composition 9A, which did not contain any DADMAC monomer. The reduction in SiO removal rate for Polishing Compositions 9B and 9C further improved the SiN / SiO selectivity by approximately 5-fold and 6-fold, respectively, compared to Polishing Composition 9A. Furthermore, the selectivity of the polysilicon polishing behavior changed from selective SiO removal in Polishing Composition 9A to favoring the removal of polysilicon over SiO in Polishing Compositions 9B and 9C, which contained DADMAC monomer.

[0131] The use of the terms "a" and "an," as well as "the" and "at least one," and similar referents in connection with the description of the invention (particularly in connection with the claims that follow) should be considered to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term "at least one" followed by a list of one or more items, "e.g., at least one of A and B," should be considered to mean one item (A or B) selected from the listed items or any combination of two or more of the listed items (A and B), unless otherwise indicated or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" should be considered to be open-ended (i.e., meaning "including, but not limited to"), unless otherwise indicated. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually set forth in the specification. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. Any and all examples or exemplary language (e.g., "such as") provided herein are intended to facilitate easier understanding of the invention and do not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0132] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of these preferred embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors anticipate that skilled artisans will employ such variations as appropriate, and the inventors intend the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Furthermore, any combination of the above-described elements in all possible variations thereof is encompassed by the present invention unless otherwise indicated herein or clearly contradicted by context.

Claims

1. (a) an abrasive comprising ceria particles; (b) a cationic polymer selected from cationic homopolymers, cationic copolymers comprising at least one cationic monomer and at least one nonionic monomer, and combinations thereof; (c) a quaternary ammonium salt or a quaternary phosphonium salt; (d) water; 1. A chemical-mechanical polishing composition comprising: The polishing composition has a pH of about 5 to about 8.

2. The polishing composition of claim 1 comprising about 0.01 wt. % to about 1 wt. % ceria particles.

3. 2. The polishing composition of claim 1, wherein the ceria particles have an average particle size of about 60 nm to about 120 nm.

4. 10. The polishing composition of claim 1, comprising a cationic homopolymer, the polishing composition comprising about 1 ppm to about 200 ppm of the cationic homopolymer.

5. 5. The polishing composition of claim 4, wherein the cationic homopolymer consists essentially of quaternary amine groups as repeat units, and the quaternized amine groups are acyclic or incorporated within a cyclic structure.

6. 10. The polishing composition of claim 1, comprising a cationic copolymer, the polishing composition comprising about 1 ppm to about 1000 ppm of the cationic copolymer.

7. The cationic copolymer comprises at least one cationic monomer and at least one The polishing composition of claim 6 , comprising a nonionic monomer of the formula:

8. 2. The polishing composition of claim 1, comprising a quaternary ammonium salt, the quaternary ammonium being a halide comprising a quaternary ammonium cation having a molecular weight of about 75 g / mol or greater.

9. 10. The polishing composition of claim 1, comprising a quaternary ammonium salt, the polishing composition comprising about 10 ppm to about 1000 ppm of the quaternary ammonium salt.

10. 2. The polishing composition of claim 1, comprising a quaternary phosphonium salt, wherein the quaternary phosphonium salt is a halide comprising a quaternary phosphonium cation having a molecular weight of about 94 g / mol or greater.

11. 2. The polishing composition of claim 1, comprising a quaternary phosphonium salt selected from the group consisting of benzyltriphenylphosphonium salts, dimethyldiphenylphosphonium salts, tetrabutylphosphonium salts, tetramethylphosphonium salts, tetraphenylphosphonium salts, tetrapropylphosphonium salts, tetraoctylphosphonium salts, butyltriphenylphosphonium salts, tetraethylphosphonium salts, tributyldodecylphosphonium salts, ethyltriphenylphosphonium salts, hexyltriphenylphosphonium salts, heptyltriphenylphosphonium salts, isopropyltriphenylphosphonium salts, methyltriphenylphosphonium salts, tributylmethylphosphonium salts, tributyloctylphosphonium salts, triphenylpropylphosphonium salts, tributylhexylphosphonium salts, and combinations thereof, wherein the polishing composition contains about 10 ppm to about 1000 ppm of the quaternary phosphonium salt.

12. 1. A method of chemical mechanical polishing a substrate, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) (a) an abrasive comprising ceria particles; (b) a cationic polymer selected from cationic homopolymers, cationic copolymers comprising at least one cationic monomer and at least one nonionic monomer, and combinations thereof; (c) a quaternary ammonium salt or a quaternary phosphonium salt; (d) water; and having a pH of about 5 to about 8. providing a chemical-mechanical polishing composition; (iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition; (v) moving the polishing pad and chemical-mechanical polishing composition relative to the substrate to abrade a portion of the surface of the substrate, thereby polishing the substrate; A method comprising:

13. The method of claim 12 , wherein the chemical-mechanical polishing composition comprises about 0.01 wt % to about 1 wt % ceria particles.

14. The method of claim 12, wherein the ceria particles have an average particle size of about 60 nm to about 120 nm.

15. The method of claim 12, wherein the chemical-mechanical polishing composition comprises a cationic homopolymer and comprises about 10 ppm to about 100 ppm of the cationic homopolymer.

16. 16. The method of claim 15, wherein the cationic homopolymer consists essentially of cationic monomer repeat units.

17. The method of claim 12, wherein the chemical-mechanical polishing composition comprises a cationic copolymer and comprises from about 1 ppm to about 1000 ppm of the cationic copolymer.

18. 20. The method of claim 17, wherein the cationic copolymer comprises at least one cationic monomer and at least one non-ionic monomer.

19. 13. The method of claim 12, wherein the chemical-mechanical polishing composition comprises a quaternary ammonium salt, the quaternary ammonium salt comprising a quaternary ammonium cation having a molecular weight of about 75 g / mol or greater.

20. The chemical mechanical polishing composition includes a quaternary ammonium salt, and the quaternary ammonium salt is selected from the group consisting of tetramethylammonium salt, tetraethylammonium salt, tetrapropylammonium salt, tetrabutylammonium salt, tetrapentylammonium salt, tetrahexylammonium salt, tetraheptylammonium salt, tetraoctylammonium salt, tetradodecylammonium salt, diallyldimethylammonium salt and derivatives thereof, benzalkonium salt, N-alkylmethylimidazolium salt, N,N-diarylimidazolium salt, N-alkylpyridinium salt, didecyldimethylammonium salt, tetrabenzylammonium salt, benzyldimethyldecylammonium salt, and benzyl dimethylhexylammonium salt, benzyldimethyloctylammonium salt, benzyldodecyldimethylammonium salt, benzyltributylammonium salt, benzyltriethylammonium salt, benzyltrimethylammonium salt, decyltrimethylammonium salt, didodecyldimethylammonium salt, dodecylethyldimethylammonium salt, dodecyltrimethylammonium salt, hexyltrimethylammonium salt, methyltrioctylammonium salt, tributylmethylammonium salt, tridodecylmethylammonium salt, triethylhexylammonium salt, triethylmethylammonium salt, trimethyloctylammonium salt, and trimethylphenylammonium salt. trihexyltetradecylammonium salt, [(3-methacryloylamino)propyl]trimethylammonium salt, (3-acrylamidopropyl)trimethylammonium salt, 2-(acryloyloxy)ethyltrimethylammonium salt, (vinylbenzyl)trimethylammonium salt, choline salt, tris(2-hydroxyethyl)methylammonium salt, and the like, and the chemical-mechanical polishing composition comprises about 100 ppm to about 1000 ppm of the quaternary ammonium salt.

20. The method of claim 19.

21. 13. The method of claim 12, wherein the chemical mechanical polishing composition comprises a quaternary phosphonium salt, the quaternary phosphonium salt being a halide comprising a quaternary phosphonium cation having a molecular weight of about 94 g / mol or greater.

22. 22. The method of claim 21, wherein the chemical-mechanical polishing composition comprises a quaternary phosphonium salt selected from the group consisting of benzyltriphenylphosphonium salts, dimethyldiphenylphosphonium salts, tetrabutylphosphonium salts, tetramethylphosphonium salts, tetraphenylphosphonium salts, tetrapropylphosphonium salts, tetraoctylphosphonium salts, butyltriphenylphosphonium salts, tetraethylphosphonium salts, tributyldodecylphosphonium salts, ethyltriphenylphosphonium salts, hexyltriphenylphosphonium salts, heptyltriphenylphosphonium salts, isopropyltriphenylphosphonium salts, methyltriphenylphosphonium salts, tributylmethylphosphonium salts, tributyloctylphosphonium salts, triphenylpropylphosphonium salts, tributylhexylphosphonium salts, and combinations thereof, and the chemical-mechanical polishing composition comprises from about 100 ppm to about 1000 ppm of the quaternary phosphonium salt.

23. 13. The method of claim 12, wherein the substrate comprises silicon nitride on a surface thereof, and at least a portion of the silicon nitride on the surface of the substrate is ground away at any removal rate to polish the substrate.

24. 24. The method of claim 23, wherein the substrate further comprises silicon oxide on a surface thereof, and at least a portion of the silicon oxide on the surface of the substrate is ground away at a removal rate such that the substrate is polished, the silicon oxide removal rate being lower than the silicon nitride removal rate.

25. 13. The method of claim 12, wherein the substrate includes polysilicon on a surface thereof, and at least a portion of the polysilicon on the surface of the substrate is ground away at any removal rate to polish the substrate.

26. 26. The method of claim 25, wherein the substrate further comprises silicon oxide on a surface thereof, and at least a portion of the silicon oxide on the surface of the substrate is ground away at a removal rate such that the substrate is polished, the silicon oxide removal rate being lower than the polysilicon removal rate.

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