Compositions and methods for silicon nitride CMP

Abstract

The present invention provides a chemical-mechanical polishing composition for polishing silicon nitride-containing substrates. The composition includes an aqueous carrier, cationic silica particles dispersed in the aqueous carrier, the cationic silica abrasive particles having a zeta potential of at least 10 mV in the polishing composition, and a polishing additive selected from the group consisting of polyetheramines, polysilamines, polyvinylimidazoles, and combinations thereof, where the polyetheramines and polysilamines have a corresponding weight average molecular weight of about 1,000 g / mol or less. The composition has a pH greater than about 6. A method for polishing silicon nitride-containing substrates is also provided.

Description

[Background technology]

[0001] Compositions and methods for planarizing or polishing the surface of a substrate are well known in the art. Abrasive 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. Abrasive compositions are typically used in combination with a polishing pad (e.g., abrasive cloth or disk). Instead of or in addition to being suspended in the polishing composition, the abrasive material may be incorporated into the polishing pad.

[0002] In the formation of microelectronic transistors, a poly-open polishing process using at least two chemical mechanical polishing (CMP) steps is useful. A hard mask such as silicon nitride is deposited on a substrate having a gate oxide layer and a polysilicon layer. An interlevel dielectric material such as silicon dioxide is deposited on the silicon nitride layer to cover the substrate. A first CMP process is used to remove a portion of the interlevel dielectric layer, preferably remaining on the silicon nitride layer. A second CMP process is then used to remove the silicon nitride layer covering the polysilicon layer to expose the polysilicon. To achieve a very planar surface, it is desirable to use a polishing composition that has selectivity for silicon nitride over silicon oxide and polysilicon.

[0003] In another application, a microelectronic transistor includes both a metal gate and a self-aligned contact structure. Typically, the metal gate is covered by a hard mask layer, such as silicon nitride, before forming the self-aligned contact structure to prevent the metal gate from being etched during the process of forming the self-aligned contact structure. A CMP process is then used to remove the excess silicon nitride from the surface. To efficiently achieve a very planar surface, it is desirable to use a polishing composition that has a high silicon nitride removal rate and produces low defects.

[0004] Existing platforms that offer high silicon nitride ("SiN") to silicon oxide selectivity are anionic silica or ceria based. For example, one common method for selective nitride polishing stop in tetraethyl orthosilicate ("TEOS") applications includes cationic ceria particles at pH 7.0 and a cationic suppressor such as polyvinylimidazole. However, long-term slurry stability issues, inconsistent selectivity performance due to small tool / process condition variations, and ceria defect issues requiring hydrogen fluoride for cleaning make the existing platforms not an ideal solution for customers.

[0005] In addition, some existing polishing compositions, especially those containing ceria abrasives, have limited ability to be concentrated due to the instability of the polishing composition above a certain concentration, leading to precipitation of the abrasive components. Thus, the instability of concentrated polishing compositions necessitates the production of more dilute polishing compositions, which increases the amount of material that must be transported and stored.

[0006] Thus, there remains a need in the art for polishing compositions and methods that can provide desirable selectivity for silicon nitride while exhibiting improved dispersion stability, and that have suitable removal rates, low defectivity, and suitable dishing performance. Summary of the Invention

[0007] The present invention provides a chemical mechanical polishing composition for polishing silicon nitride-containing substrates. The composition includes an aqueous carrier, cationic silica abrasive particles dispersed in the aqueous carrier, the cationic silica abrasive particles having a zeta potential of at least 10 mV in the polishing composition, and a polishing additive selected from the group consisting of polyetheramines, polysilamines, polyvinylimidazoles, and combinations thereof, the polyetheramines and polysilamines having a corresponding weight average molecular weight of about 1,000 g / mol or less. The polishing composition has a pH greater than about 6. A method for chemical mechanical polishing a substrate comprising silicon nitride is further disclosed. The method may include contacting the substrate with the above-mentioned polishing composition, moving the polishing composition relative to the substrate, and grinding the substrate to remove a portion of the silicon nitride layer from the substrate, thereby polishing the substrate. In certain embodiments, the method may advantageously allow the removal rate of the silicon nitride layer to be more than four times the removal rate of the silicon oxide layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A chemical mechanical polishing composition for polishing silicon nitride-containing substrates is disclosed. The composition includes an aqueous carrier, cationic silica abrasive particles dispersed in the aqueous carrier, the cationic silica abrasive particles having a zeta potential of at least 10 mV in the polishing composition, and a polishing additive selected from the group consisting of polyetheramines, polysilamines, polyvinylimidazoles, and combinations thereof, the polyetheramines and polysilamines having a corresponding weight average molecular weight of about 1,000 g / mol or less. The polishing composition has a pH of greater than about 6. In certain embodiments, the polyetheramines and polysilamines can have a corresponding weight average molecular weight of less than about 600 g / mol.

[0009] The chemical mechanical polishing composition comprises cationic silica abrasive particles, which are desirably suspended in an aqueous carrier (e.g., water). The cationic silica abrasive particles are typically in particulate form. Preferably, the cationic silica abrasive particles comprise, consist essentially of, or consist of silica particles, specifically colloidal silica particles. Colloidal silica particles are prepared via wet processes and are typically non-agglomerated individual discrete particles, generally spherical or nearly spherical, but may have other shapes (e.g., shapes generally having elliptical, square, or rectangular cross sections). Such particles are structurally distinct from fumed particles, which are typically prepared via heat treatment or flame hydrolysis processes and are chain-like structures of aggregated primary particles.

[0010] The particle size of a particle is the diameter of the smallest sphere that encompasses the particle. The cationic silica abrasive particles can have any suitable particle size. The cationic silica abrasive particles can have an average (i.e., mean) particle size of about 5 nm or more (e.g., about 10 nm or more, about 15 nm or more, about 20 nm or more, about 30 nm or more, about 40 nm or more, or about 50 nm or more). Alternatively or in addition, the cationic silica abrasive particles can have an average particle size of about 200 nm or less (e.g., about 180 nm or less, about 160 nm or less, about 150 nm or less, about 130 nm or less, about 80 nm or less, about 60 nm or less, or about 50 nm or less). Thus, the cationic silica abrasive particles can have an average particle size within a range bounded by any two of the aforementioned endpoints. For example, the cationic silica abrasive particles can have an average particle size of about 5 nm to about 200 nm (e.g., about 20 nm to about 180 nm, about 15 nm to about 150 nm, about 20 nm to about 80 nm, or about 20 nm to about 60 nm). In some embodiments, the cationic silica abrasive particles have an average particle size of about 20 nm to about 80 nm. In one particular embodiment, the cationic silica abrasive particles have an average particle size of about 50 nm.

[0011] Any suitable amount of cationic silica abrasive particles can be present in the polishing composition. In some embodiments, cationic silica abrasive particles can be present in the polishing composition at a concentration of about 0.0005% by weight or more (e.g., about 0.001% by weight or more, 0.0025% by weight or more, about 0.005% by weight or more, about 0.01% by weight or more, about 0.025% by weight or more, or about 0.05% by weight or more). Typically, cationic silica abrasive particles are present in the polishing composition at a concentration of about 0.025% by weight or more (e.g., about 0.05% by weight or more, about 0.1% by weight or more, about 0.25% by weight or more, about 0.5% by weight or more, about 1% by weight or more, or about 2% by weight or more). Alternatively or in addition, the cationic silica abrasive particles can be present in the polishing composition at a concentration of about 30% by weight or less (e.g., about 25% by weight or less, about 20% by weight or less, about 15% by weight or less, about 10% by weight or less, about 5% by weight or less, about 3% by weight or less, or about 2% by weight or less).Thus, the cationic silica abrasive particles can be present in the polishing composition at a concentration within a range bounded by any two of the aforementioned endpoints. For example, the cationic silica abrasive particles can be present in the polishing composition at a concentration of about 0.0005% to about 10% by weight (e.g., about 0.001% to about 10% by weight, about 0.005% to about 10% by weight, about 0.01% to about 10% by weight, about 0.05% to about 10% by weight, about 0.1% to about 5% by weight, about 0.1% to about 3% by weight, about 0.1% to about 2% by weight, or about 0.2% to about 2% by weight). In certain embodiments, the cationic silica abrasive particles are present in the polishing composition at a concentration of about 0.025% to about 1% by weight.

[0012] In certain embodiments, the cationic silica abrasive particles have a zeta potential in the polishing composition of about 10 mV or more (e.g., about 15 mV or more, about 20 mV or more, about 25 mV or more, or about 30 mV or more) (e.g., at a pH greater than about 6 or in a range of about 6 to about 8). The cationic silica abrasive particles can have a zeta potential in the polishing composition of about 50 mV or less (e.g., about 45 mV or less, or about 40 mV or less) (e.g., at a pH greater than about 6 or in a range of about 6 to about 8). It will be understood that the cationic silica abrasive particles can have a zeta potential in a range bounded by any two of the aforementioned endpoints. For example, the cationic silica abrasive particles can have a zeta potential in the polishing composition (at a pH greater than about 6, or at a pH in the range of about 6 to about 8) in the range of about 10 mV to about 50 mV (e.g., about 10 mV to about 45 mV, or about 20 mV to about 40 mV).

[0013] In certain embodiments, the cationic silica abrasive particles may comprise colloidal silica particles treated with an aminosilane compound such that the treated abrasive particles have a zeta potential of about 10 mV or more (e.g., about 15 mV or more, about 20 mV or more, about 25 mV or more, or about 30 mV or more) in the polishing composition (e.g., at a pH of about 6 or more, about 7 or more, about 7.5 or more, or about 8 or more). In certain of these embodiments, the abrasive particles comprise colloidal silica particles treated with a quaternary aminosilane compound. Such cationic colloidal silica particles may be obtained by treating the particles with at least one aminosilane compound, for example, as disclosed in commonly assigned U.S. Pat. Nos. 7,994,057 and 9,028,572, or U.S. Pat. No. 9,382,450, each of which is incorporated herein by reference in its entirety. Colloidal silica particles having a zeta potential of about 10 mV or greater in the polishing composition can also be obtained through the incorporation of chemical species such as aminosilane compounds into the colloidal silica particles, as disclosed in commonly assigned U.S. Pat. No. 9,422,456, the entirety of which is incorporated herein by reference.

[0014] It will be understood that the exemplary cationic colloidal silica particles can be treated using any suitable treatment method to obtain cationic colloidal silica particles.For example, the quaternary aminosilane compound and colloidal silica can be added simultaneously with some or all of the other components of the polishing composition.Alternatively, the colloidal silica can be treated with the quaternary aminosilane compound (for example, by heating the mixture of colloidal silica and aminosilane) before mixing with other components in the polishing composition.

[0015] In some embodiments, the cationic silica abrasive particles have a surface that is treated with at least one silane compound, aminosilane compound, phosphononium silane compound, or sulfonium silane compound. In certain embodiments, the surface of the cationic silica abrasive particles is treated with a primary aminosilane, a secondary aminosilane, a tertiary aminosilane, a quaternary aminosilane, a dipodal aminosilane, or a combination thereof. Suitable silane compounds include aminosilanes such as aminopropyltrialkoxysilane, bis(2-hydroxyethyl)-3-aminopropyltrialkoxysilane, diethylaminomethyltrialkoxysilane, (N,N-diethyl-3-aminopropyl)trialkoxysilane), 3-(N-styrylmethyl)-2-aminoethylaminopropyltrialkoxysilane, 2-(N-benzylaminoethyl)-3-aminopropyltrialkoxysilane, trialkoxysilylpropyl-N,N,N-trimethylammonium chloride, N-(trialkoxysilylethyl)benzyl-N,N,N-trimethylammonium chloride, bis(methyldialkoxysilylpropyl)-N-methylamine, bis(trialkoxysilylpropyl)urea, bis(3-(trialkoxysilyl)propyl)-ethylenediamine, and bis(trialkoxysilylpropyl)amine. The alkoxy groups of the above aminosilane compounds can be replaced with other hydrolyzable groups such as halides, amines, and carboxylates. In certain embodiments, the cationic silica abrasive particles have a surface that is treated with a quaternary aminosilane, a dipodal aminosilane, or a combination thereof. The choice of silane compound depends, in part, on the type of substrate being polished.

[0016] Preferably, the surface-treated cationic silica abrasive particles have a particle size that is the same as or larger than the particle size of the untreated cationic silica abrasive particles. More specifically, the surface-treated cationic silica abrasive particles may have a particle size that is less than about 2 times the particle size of the untreated cationic silica particles, less than about 1.7 times the particle size of the untreated cationic silica particles, less than about 1.4 times the particle size of the untreated cationic silica particles, or less than about 1.2 times the particle size of the untreated cationic silica particles. The surface-treated cationic silica abrasive particles preferably have a particle size that is about the same as the particle size of the untreated cationic silica abrasive particles. For example, the surface-treated cationic silica abrasive particles may have an average particle size of about 5 nm or more (e.g., about 10 nm or more, about 15 nm or more, about 20 nm or more, about 30 nm or more, about 40 nm or more, or about 50 nm or more). Alternatively or additionally, the surface-treated cationic silica abrasive particles may have an average particle size of about 200 nm or less (e.g., about 180 nm or less, about 160 nm or less, about 150 nm or less, about 130 nm or less, about 80 nm or less, about 60 nm or less, or about 50 nm or less). Thus, the surface-treated cationic silica abrasive particles may have an average particle size within a range bounded by any two of the aforementioned endpoints. For example, the surface-treated cationic silica abrasive particles may have a particle size of about 5 nm to about 200 nm (e.g., about 20 nm to about 180 nm, about 15 nm to about 150 nm, about 20 nm to about 80 nm, or about 20 nm to about 60 nm). In some embodiments, the surface-treated cationic silica abrasive particles have an average particle size of about 20 nm to about 80 nm. In a preferred embodiment, the surface-treated cationic silica abrasive particles have an average particle size of about 50 nm.

[0017] Any suitable method of surface treating the cationic silica abrasive particles, many of which are known to those skilled in the art, can be used in accordance with the present invention. For example, the cationic silica abrasive particles can be treated with an aminosilane compound prior to mixing with the other components of the polishing composition, or the aminosilane and cationic silica abrasive particles can be added simultaneously with some or all of the other components of the polishing composition.

[0018] The silane with which the cationic silica abrasive particles are treated preferably does not cover all of the available silanol sites on the cationic silica abrasive particles. Typically, the surface-treated cationic silica abrasive particles have a surface coverage of available silanols of about 2% or more (e.g., about 4% or more, about 8% or more, or about 10% or more). The surface-treated cationic silica abrasive particles preferably have a surface coverage of available silanols of about 50% or less (e.g., about 30% or less, about 25% or less, about 20% or less, about 15% or less, or about 10% or less). Thus, the surface-treated cationic silica abrasive particles may have a surface coverage of available silanols within a range bounded by any two of the aforementioned endpoints. For example, the surface-treated cationic silica abrasive particles may have a surface coverage of available silanols of about 2% to about 50% (e.g., about 2% to about 30%, about 2% to about 20%, or about 4% to about 15%). The surface silanol concentration is 5SiOH / nm, which is the standard value for surface-treated cationic silica abrasive particles. 2 , and the BET surface area of ​​the surface-treated cationic silica grinding particles can be estimated using

[0019] The aminosilane compound may be present in the polishing composition in any suitable amount. In some embodiments, the polishing composition comprises about 30 ppm or more (e.g., about 50 ppm or more, about 100 ppm or more, about 200 ppm or more, about 300 ppm or more, about 400 ppm or more, or about 500 ppm or more) of the aminosilane compound. Alternatively or in addition, the polishing composition comprises about 2000 ppm or less (e.g., about 1000 ppm or less, about 800 ppm or less, or about 600 ppm or less) of the aminosilane compound. Thus, the polishing composition may comprise about 30 ppm to about 2000 ppm (e.g., about 100 ppm to about 1000 ppm, about 200 ppm to about 800 ppm, about 250 ppm to about 700 ppm, or about 275 ppm to about 600 ppm) of the aminosilane compound.

[0020] The zeta potential of a particle refers to the difference between the charge of the ions surrounding the particle and the charge of the bulk solution (e.g., the aqueous carrier and any other components dissolved therein). Thus, silica abrasive particles having a positive charge (i.e., cationic silica abrasive particles) will have a positive zeta potential at their operating pH. In some embodiments, the cationic silica abrasive particles and / or surface-treated cationic silica abrasive particles have a positive zeta potential at a pH of about 9.5 or less (e.g., about 9 or less, about 8 or less, about 7 or less, about 6 or less, about 5 or less, about 4 or less, or about 3 or less). In certain embodiments, the cationic silica abrasive particles and / or surface-treated cationic silica abrasive particles have a zeta potential of at least +10 mV at a pH of greater than about 6. Thus, the cationic silica abrasive particles and / or surface-treated cationic silica abrasive particles may have a zeta potential of about +10 mV or more (e.g., about +15 mV or more, about +20 mV or more, about +25 mV or more, or about +30 mV or more) at a pH of about 6 to about 8. Alternatively or in addition, the cationic silica abrasive particles and / or treated cationic silica abrasive particles may have a zeta potential of about +60 mV or less (e.g., about +55 mV or less, about +50 mV or less, about +45 mV or less, about +40 mV or less, or about +35 mV or less) at a pH of about 6 to about 8. Thus, the cationic silica abrasive particles and / or surface-treated cationic silica abrasive particles may have a zeta potential within a range bounded by any of the aforementioned endpoints. For example, the cationic silica abrasive particles and / or surface-treated cationic silica abrasive particles can have a zeta potential of about +10 mV to about +60 mV (e.g., about +10 mV to about +50 mV, about +15 mV to about +40 mV, or about +20 mV to about +40 mV) at a pH of about 6 to about 8.

[0021] In certain embodiments, the polishing composition may include a polishing additive to increase the polishing selectivity of the silicon nitride layer to the silicon oxide layer. For example, the polishing additive may allow the removal rate of the silicon nitride layer to exceed the removal rate of the silicon oxide layer, such that the selectivity of silicon nitride to silicon oxide may be greater than about 1:1 (e.g., greater than about 2:1, or greater than about 4:1, or greater than about 10:1, or greater than about 20:1).

[0022] In some embodiments, the polishing additive may include polyetheramine, polysilamine, polyvinylimidazole, or a combination thereof. Typically, the polyetheramine or polysilamine has a weight average molecular weight of less than about 1,000 g / mol, for example, about 900 g / mol or less, about 800 g / mol or less, about 700 g / mol or less, about 600 g / mol or less, or about 500 g / mol or less. Alternatively or in addition, the polyetheramine or polysilamine has a weight average molecular weight of about 50 g / mol or more, for example, about 75 g / mol or more, about 100 g / mol or more, about 150 g / mol or more, or about 200 g / mol or more. Thus, the polyetheramine or polysilamine may have an average molecular weight limited by any two of the aforementioned endpoints. For example, the polyetheramine or polysilamine may have an average molecular weight of about 50 g / mol to about 900 g / mol, about 50 g / mol to about 800 g / mol, about 50 g / mol to about 700 g / mol, about 50 g / mol to about 600 g / mol, about 50 g / mol to about 500 g / mol, about 75 g / mol to about 900 g / mol, about 100 g / mol to about 900 g / mol, about 150 g / mol to about 900 g / mol, about 200 g / mol to about 900 g / mol, about 100 g / mol to about 800 g / mol, or about 100 g / mol to about 600 g / mol. In some embodiments, the polyetheramine or polysilamine has a weight average molecular weight of about 800 g / mol or less. In certain embodiments, the polyetheramine or polysilamine has a weight average molecular weight of about 600 g / mol or less.

[0023] In embodiments in which the polishing additive comprises a polyetheramine, the composition may comprise any suitable polyetheramine. Typically, the polyetheramine is selected from propylene oxide diamines, propylene oxide triamines, ethylene oxide / propylene oxide diamines, ethylene oxide / propylene oxide triamines, or combinations thereof. Exemplary polyetheramine compounds include the JEFFAMINE™ family of amines, available from Huntsman (The Woodlands, TX). JEFFAMINE™ polyetheramines may comprise a polyether backbone based on either propylene oxide ("PO"), ethylene oxide ("EO"), or mixed EO / PO (e.g., O,O'-bis(2-aminopropyl)polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol).

[0024] As used herein, the term "propylene oxide diamine" refers to a chemical structure that includes at least one propylene oxide subunit and two amine moieties. In some embodiments, at least one propylene oxide subunit is a polypropylene oxide subunit.

[0025] As used herein, the term "propylene oxide triamine" refers to a chemical structure that includes at least one propylene oxide subunit and three amine moieties. In some embodiments, the at least one propylene oxide subunit is a polypropylene oxide subunit.

[0026] As used herein, the term "ethylene oxide / propylene oxide diamine" refers to a chemical structure that includes at least one ethylene oxide subunit, at least one propylene oxide subunit, and two amine moieties. In some embodiments, at least one propylene oxide subunit is a polypropylene oxide subunit and at least one ethylene oxide subunit is a polyethylene oxide subunit, or at least one propylene oxide subunit is a polypropylene oxide subunit and at least one ethylene oxide subunit is a polyethylene oxide subunit. Thus, ethylene oxide / propylene oxide diamines can include block or random copolymers of ethylene oxide, propylene oxide, or combinations thereof.

[0027] As used herein, the term "ethylene oxide / propylene oxide triamine" refers to a chemical structure that includes at least one ethylene oxide subunit, at least one propylene oxide subunit, and three amine moieties. In some embodiments, at least one propylene oxide subunit is a polypropylene oxide subunit and at least one ethylene oxide subunit is a polyethylene oxide subunit, or at least one propylene oxide subunit is a polypropylene oxide subunit and at least one ethylene oxide subunit is a polyethylene oxide subunit. Thus, ethylene oxide / propylene oxide triamine can include block or random copolymers of ethylene oxide, propylene oxide, or combinations thereof.

[0028] As used herein, the term "amine moiety" refers to a nitrogen-containing chemical moiety. The amine moiety may be substituted or unsubstituted. Thus, the amine moiety may be a primary, secondary, or tertiary amine. The reactivity of the polyetheramines and / or polysilamines may be modified by interrupting the primary amines or through secondary amine functionality. Generally, the amine moieties are primary amine substituents.

[0029] In some embodiments, the polyetheramine is of formula (I): [ka] wherein R is a C1-C6 alkyl group (i.e., 1, 2, 3, 4, 5, or 6 carbon units in length), and x, y, and z are independently integers from 0 to 15 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15). In certain embodiments, x, y, and z are independently integers from 0 to about 10. In some embodiments, x, y, and z refer to the average (rounded to the nearest integer) chain length (i.e., average carbon chain length or average propylene oxide chain length) of the specified subunits. In some embodiments, the C1-C6 alkyl group is saturated, unsaturated, branched, straight chain, cyclic, or a combination thereof. Exemplary enumerations of C1-C6 alkyl groups are methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, neo-pentyl, or hexyl. In certain embodiments, the C1-C6 alkyl group is substituted with one or more alkyl substituents, aryl substituents, heteroatoms, or combinations thereof (e.g., benzyl, phenylethyl, phenylpropyl, etc.). In some embodiments, the C1-C6 alkyl group can be a C1-C6 heteroalkyl group (i.e., 1, 2, 3, 4, 5, or 6 carbon units in length). As used herein, "heteroalkyl group" refers to a saturated or unsaturated, substituted or unsubstituted, linear, branched, or cyclic aliphatic group that contains at least one heteroatom (e.g., O, S, N, and / or P) in the core (i.e., carbon backbone) of the molecule.

[0030] In some embodiments, the polyetheramine is of formula (II): [ka] wherein a is an integer from 0 to 15 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15). In certain embodiments, a is an integer from 0 to about 10. In some embodiments, a refers to the average (rounded to the nearest integer) chain length of the specified subunits (i.e., the average carbon chain length or the average polyethylene oxide chain length).

[0031] In some embodiments, the polyetheramine is of formula (III): [ka] wherein b, c, and d are independently integers from 0 to 15 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15). In certain embodiments, b, c, and d are independently integers from 0 to about 10. In some embodiments, b, c, and d refer to the average (rounded to the nearest integer) chain length (i.e., average carbon chain length or average ethylene oxide / propylene oxide chain length) of the specified subunits.

[0032] In some embodiments, the polyetheramine is of formula (IV): [ka] where e is an integer from 0 to 15 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15). In certain embodiments, e is an integer from 0 to about 10. In some embodiments, a refers to the average (rounded to the nearest integer) chain length of the specified subunits (i.e., the average carbon chain length or the average polyethylene oxide chain length).

[0033] In some embodiments, the polyetheramine is JEFFAMINE™ D-230 (Formula II) having a molecular weight of approximately 230, JEFFAMINE™ D-400 (Formula II) having a molecular weight of approximately 400, JEFFAMINE™ T-403 (Formula I) having a molecular weight of approximately 400, JEFFAMINE™ ED-600 (Formula III) having a molecular weight of approximately 600, JEFFAMINE™ ED-900 (Formula III) having a molecular weight of approximately 900, 4,7,10-trioxa-1,13-tridecanediamine (Formula IV), or a combination thereof.

[0034] In the embodiment in which the polishing additive comprises polyetheramine, the polishing composition may comprise any suitable amount of polyetheramine.For example, polyetheramine may be present in the polishing composition at a concentration of about 0.005 mM or more (e.g., about 0.01 mM or more, about 0.025 mM or more, about 0.05 mM or more, about 0.07 mM or more, or about 0.1 mM or more).Alternatively or in addition, polyetheramine may be present in the polishing composition at a concentration of about 5 mM or less (e.g., about 4 mM or less, about 3 mM or less, about 2 mM or less, about 1 mM or less, about 0.5 mM or less, or about 0.25 mM or less).Thus, polyetheramine may be present in the polishing composition at a concentration within a range bounded by any two of the aforementioned endpoints. For example, the polyetheramine can be present in the polishing composition at a concentration of about 0.005 mM to about 5 mM (e.g., about 0.01 mM to about 5 mM, about 0.025 mM to about 5 mM, about 0.05 mM to about 5 mM, about 0.1 mM to about 5 mM, about 0.25 mM to about 5 mM, about 0.005 mM to about 0.5 mM, about 0.01 mM to about 0.5 mM, about 0.025 mM to about 0.5 mM, about 0.05 mM to about 0.5 mM, or about 0.07 mM to about 0.25 mM).

[0035] In some embodiments, the polishing additive comprises a polysilamine. As used herein, the term "polysilamine" refers to a compound that comprises a silicone subunit and at least one amine moiety. Exemplary polysilamine compounds include the SILAMINE™ family of polysilamines available from Siltech Corporation (Toronto, Ontario). In one particular embodiment, the polysilamine is SILAMINE™ A0 EDA available from Siltech Corporation.

[0036] In some embodiments, the polysilamine is of formula (V): [ka] wherein p and q are independently integers from 0 to 15 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15). In certain embodiments, p and q are independently integers from 0 to about 10. In some embodiments, p and q refer to the average (rounded to the nearest integer) chain length of the specified subunits (i.e., the average silicon oxide chain length).

[0037] In the embodiment in which the polishing additive comprises polysilamine, the polysilamine can be present in the polishing composition at any suitable concentration.For example, the polysilamine can be present in the polishing composition at a concentration of about 0.005 mM or more (e.g., about 0.01 mM or more, about 0.025 mM or more, about 0.05 mM or more, about 0.1 mM or more, or 0.25 mM or more).Alternatively or in addition, the polysilamine can be present in the polishing composition at a concentration of about 5 mM or less (e.g., about 4 mM or less, about 3 mM or less, about 2 mM or less, about 1 mM or less, or about 0.5 mM or less).Thus, the polysilamine can be present in the polishing composition at a concentration that is limited by any two of the aforementioned endpoints. For example, the polysilamine can be present in the polishing composition at a concentration of about 0.005 mM to about 5 mM (e.g., about 0.01 mM to about 5 mM, about 0.025 mM to about 5 mM, about 0.05 mM to about 5 mM, about 0.1 mM to about 5 mM, about 0.25 mM to about 5 mM, about 0.005 mM to about 0.5 mM, about 0.01 mM to about 0.5 mM, about 0.025 mM to about 0.5 mM, or about 0.05 mM to about 0.5 mM).

[0038] In some embodiments, the polishing additive comprises polyvinylimidazole. As used herein, the term "polyvinylimidazole" refers to one or more polymers selected from polyvinylimidazole, derivatives of polyvinylimidazole, copolymers of vinylimidazole, and copolymers of vinylimidazole derivatives (collectively referred to as "PVI"). In certain embodiments, the polyvinylimidazole is poly-N-vinylimidazole. In some embodiments, the copolymers of polyvinylimidazole contain monomers selected from acrylic acid esters, acrylic acid amides, methacrylic acid esters, methacrylic acid amides, acrylonitrile, vinyl pyrrolidone, and vinyl chloride. In certain embodiments, the polyvinylimidazole is basotronic polyvinylimidazole.

[0039] In embodiments in which the polishing additive comprises polyvinylimidazole, polyvinylimidazole can be present in the polishing composition at any suitable concentration. In some embodiments, polyvinylimidazole can be present in the polishing composition at a concentration of about 0.005 mM or more (e.g., about 0.01 mM or more, about 0.025 mM or more, about 0.05 mM or more, about 0.1 mM or more, or about 0.25 mM or more). Alternatively or in addition, polyvinylimidazole can be present in the polishing composition at a concentration of about 5 mM or less (e.g., about 4 mM or less, about 3 mM or less, about 2 mM or less, about 1 mM or less, or about 0.5 mM or less). Thus, polyvinylimidazole can be present in the polishing composition at a concentration that is limited by any two of the aforementioned endpoints. For example, polyvinylimidazole can be present in the polishing composition at a polyvinylimidazole concentration of about 0.005 mM to about 5 mM (e.g., about 0.01 mM to about 5 mM, about 0.025 mM to about 5 mM, about 0.05 mM to about 5 mM, about 0.1 mM to about 5 mM, about 0.25 mM to about 5 mM, about 0.005 mM to about 0.5 mM, about 0.01 mM to about 0.5 mM, about 0.025 mM to about 0.5 mM, or about 0.05 mM to about 0.5 mM).

[0040] Typically, the chemical-mechanical polishing composition has a pH of greater than about 6 (e.g., greater than about 6.5, greater than about 7, greater than about 7.5, greater than about 8, greater than about 8.5, or greater than about 9) when measured at 1 atm and 25° C. In some embodiments, the polishing composition has a pH of about 6 to about 12, e.g., about 6 to about 11, about 6 to about 10, about 6 to about 9, about 6 to about 8, about 7 to about 12, about 7 to about 11, about 7 to about 10, about 7 to about 9, or about 7 to about 8. In certain embodiments, the polishing composition has a pH of about 6 to about 8 (e.g., about 7).

[0041] The chemical mechanical polishing composition may include one or more compounds capable of adjusting (i.e., adjusting) the pH of the polishing composition (i.e., pH adjusting compounds). The pH of the polishing composition may 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.

[0042] The compound capable of adjusting the pH may be selected from ammonium salts, alkali metal salts, carboxylic acids, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, borates, organic acids (e.g., acetic acid), organic bases (e.g., amines), and mixtures thereof.

[0043] The chemical-mechanical polishing composition optionally further comprises one or more chemicals. Exemplary chemicals include buffers, conditioners, biocides, scale inhibitors, dispersants, etc. In some embodiments, the chemical-mechanical polishing composition further comprises a buffer and a biocide.

[0044] In some embodiments, the chemical mechanical polishing composition further comprises a buffer. As used herein, the term "buffer" refers to any chemical capable of achieving and / or maintaining the pH of the polishing composition. For example, the buffer can be an acidic chemical, a basic chemical, a neutral chemical, or a combination thereof. An exemplary list of buffers includes nitric acid, sulfuric acid, phosphoric acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, maleic acid, ammonium hydroxide, phosphates, sulfates, acetates, malonates, oxalates, borates, ammonium salts, amines, polyols (e.g., Tris base), amino acids, and the like.

[0045] In some embodiments, the chemical-mechanical composition includes a biocide. The biocide, when present, can be any suitable biocide and can be present in any suitable amount in the polishing composition. An exemplary biocide is an isothiazolinone biocide. Typically, the amount of biocide is present in the polishing composition in an amount of about 1 ppm to about 200 ppm (e.g., about 10 ppm to about 200 ppm, about 10 ppm to about 150 ppm, about 20 ppm to about 150 ppm, about 50 ppm to about 150 ppm, about 1 ppm to about 150 ppm, or about 1 ppm to about 100 ppm).

[0046] 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 or continuous process. In general, the polishing composition is prepared by combining the components of the polishing composition. The term "component" as used herein includes individual components (e.g., cationic silica abrasive particles, optional silane compounds, polyetheramines, polysilamines, optional buffers, optional modifiers, optional biocides, optional scale inhibitors, optional dispersants, polyvinylimidazole, etc.), as well as any combination of components (e.g., cationic silica abrasive particles, optional silane compounds, polyetheramines, polysilamines, optional buffers, optional modifiers, optional biocides, optional scale inhibitors, optional dispersants, polyvinylimidazole, etc.).

[0047] For example, the polishing composition can be prepared by (i) providing all or a portion of the aqueous carrier; (ii) dispersing the cationic silica abrasive particles, and / or treated cationic silica abrasive particles, polyetheramine, and / or polysilamine, and any optional chemicals using any suitable means for preparing such dispersions; (iii) adjusting the pH of the dispersion as needed; and (iv) optionally adding suitable amounts of any other optional ingredients and / or chemicals to the mixture.

[0048] In some embodiments, the chemical mechanical composition is stored in a single container. In other embodiments, the chemical mechanical composition is stored in two or more containers, so that the chemical mechanical compositions are mixed at or near the point of use. To mix the components contained in two or more storage devices to produce a polishing composition at or near the point of use, the storage devices are typically 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. The flow lines may each lead directly to the point of use, or two or more flow lines may be combined at any point into a single flow line leading to the point of use. Additionally, any of the flow lines (e.g., individual flow lines or combined flow lines) may first lead to one or more other devices (e.g., pump devices, metering devices, mixing devices, etc.) prior to reaching the point of use of the components.

[0049] The components of the polishing composition may be delivered to the point of use independently (e.g., the components are delivered to the substrate surface and then mixed during the polishing process), or one or more of the components may be mixed before being delivered to the point of use, e.g., shortly before or immediately before delivery to the point of use. Components are combined "immediately before delivery to the point of use" if they are combined within about 5 minutes of being added 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 of being added to the platen in mixed form, or are combined simultaneously with delivery of the components to the point of use (e.g., the components are combined in a dispenser). Components are also combined "immediately before delivery to the point of use" if they are combined within 5 m of the point of use (e.g., within 1 cm of the point of use), such as within 1 m of the point of use, or even within 10 cm of the point of use.

[0050] When two or more components of the polishing composition are mixed before reaching the point of use, the components can be mixed in a flow line and delivered to the point of use without using a mixing device. Alternatively, one or more flow lines can lead to a mixing device to facilitate mixing 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 a high-pressure jet) through which two or more components flow. Alternatively, the mixing device can be a vessel-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 leave the mixer and are delivered to the point of use, either directly or through other elements of the apparatus (e.g., through one or more flow lines). Furthermore, the mixing device can include more than one chamber, each chamber having at least one inlet and at least one outlet, in which two or more components are mixed. When using a vessel-type mixing device, it is preferable that the mixing device includes a mixing mechanism to further facilitate mixing of the components. Mixing mechanisms are commonly known in the art and include stirrers, blenders, agitators, baffles with paddles, gas sparger systems, vibrators, and the like.

[0051] 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 can include the components of the polishing composition in amounts such that when the concentrate is diluted with an appropriate amount of water, each component of the polishing composition is present in the polishing composition in an amount within the appropriate range of each component listed above.For example, the cationic silica abrasive particles, and / or surface-treated cationic silica abrasive particles, polyetheramines, and / or polysiloxamines, and any optional chemicals can each be present in the concentrate in an amount of about 2 times (e.g., about 3 times, about 4 times, or about 5 times) the concentration listed above for each component, such that when the concentrate is diluted with an equal amount of water (e.g., 2 equivalents of water, 3 equivalents of water, or 4 equivalents of water, respectively), each component is present in the polishing composition in an amount within the range listed above for each component. Further, as will be appreciated by those skilled in the art, the concentrate may contain an appropriate proportion of water present in the final polishing composition to ensure that the polyetheramine, and / or polysilamine, and any optional chemicals are at least partially or completely dissolved in the concentrate. Desirably, the polishing composition of the present invention is colloidally stable when in the form of a concentrate that is 4 times more concentrated than the polishing composition at the point of use.

[0052] The present invention also provides a method for chemically mechanically polishing a substrate, the method comprising: (i) providing a substrate comprising a silicon nitride (SiN) layer on a surface of the substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition comprising: (a) cationic silica abrasive particles; (b) a polyetheramine, a polysilamine, or a combination thereof; and (c) an aqueous carrier; wherein the polyetheramine or polysilamine has a weight average molecular weight of less than about 1,000 g / mol, the polishing composition has a pH greater than about 6, and the cationic silica abrasive particles have a zeta potential of at least +10 mV at a pH greater than about 6; (iv) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the SiN layer on the surface of the substrate and polish the substrate.

[0053] The present invention further provides a method for chemically mechanically polishing a substrate, the method comprising: (i) providing a substrate comprising a silicon nitride (SiN) layer on a surface of the substrate; (ii) providing a polishing pad; (iii) providing a chemical-mechanical polishing composition comprising: (a) cationic silica abrasive particles, (b) a polyvinylimidazole derivative, and (c) an aqueous carrier, wherein the polishing composition has a pH greater than about 6, and the cationic silica abrasive particles have a zeta potential of at least +10 mV at a pH greater than about 6; (iv) contacting the substrate with the polishing pad and chemical-mechanical polishing composition; and (v) moving the polishing pad and chemical-mechanical polishing composition relative to the substrate to abrade at least a portion of the SiN layer on the surface of the substrate and polish the substrate.

[0054] 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) composed of a low-dielectric material. Suitable substrates include wafers used in the semiconductor industry. Wafers typically include or consist 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 all three of the aforementioned materials, and is particularly useful for polishing substrates that include silicon nitride.

[0055] In certain embodiments, the substrate comprises polysilicon in combination with silicon oxide and / or silicon nitride. The polysilicon may be any suitable polysilicon, many of which are known in the art. The polysilicon may have any suitable phase, and may be amorphous, crystalline, or a combination thereof. The silicon oxide may likewise be any suitable silicon oxide, many forms of which are known in the art. Suitable types of silicon oxide include, but are not limited to, borophosphosilicate glass (BPSG), PETEOS, thermal oxide, undoped silicate glass, and HDP oxide.

[0056] 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 an embodiment of the present invention, the polishing composition desirably exhibits a silicon nitride removal rate of about 500 Å / min or more, 700 Å / min or more, about 1,000 Å / min or more, about 1,250 Å / min or more, about 1,500 Å / min or more, about 1,750 Å / min or more, or about 2,000 Å / min or more.

[0057] The chemical mechanical polishing composition of the present invention desirably exhibits a low removal rate when polishing a substrate comprising silicon oxide according to the method of the present invention.For example, when polishing a silicon wafer comprising silicon oxide according to an embodiment of the present invention, such as high density plasma (HDP) oxide and / or plasma enhanced tetraethyl orthosilicate (PETEOS) and / or tetraethyl orthosilicate (TEOS), the polishing composition desirably exhibits a silicon oxide removal rate of about 800 Å / min or less, for example, about 700 Å / min or less, about 600 Å / min or less, about 500 Å / min or less, about 400 Å / min or less, about 200 Å / min or less, about 100 Å / min or less, about 75 Å / min or less, about 50 Å / min or less, or even about 25 Å / min or less.

[0058] The chemical mechanical polishing compositions of the present invention desirably exhibit low removal rates when polishing substrates containing polysilicon according to the methods of the present invention. For example, when polishing silicon wafers containing polysilicon according to embodiments of the present invention, the polishing compositions desirably exhibit polysilicon removal rates of about 1,000 Å / min or less, about 750 Å / min or less, about 500 Å / min or less, about 250 Å / min or less, about 100 Å / min or less, about 50 Å / min or less, about 25 Å / min or less, about 10 Å / min or less, or even about 5 Å / min or less.

[0059] In certain embodiments, the substrate comprises a silicon nitride (SiN) layer and a silicon oxide (SiO) layer on the surface of the substrate. In some embodiments, grinding the silicon nitride layer provides a silicon nitride removal rate, and grinding the silicon oxide layer provides a silicon oxide removal rate, with the ratio of silicon nitride removal rate to silicon oxide removal rate being greater than about 4 to 1. Thus, the chemical mechanical polishing composition of the present invention can be used to polish a substrate with a silicon nitride to silicon oxide polishing selectivity of about 4:1 or more (e.g., about 5:1 or more, about 6:1 or more, about 7:1 or more, about 8:1 or more, about 9:1 or more, about 10:1 or more, about 15:1 or more, about 20:1 or more, or about 40:1 or more). In certain embodiments, the ratio of silicon nitride removal rate to silicon oxide removal rate is greater than about 20 to 1. The chemical mechanical polishing compositions of the present invention can be tailored to provide effective polishing in the desired polishing range that is selective for a particular thin layer material while minimizing surface defects, defects, corrosion, erosion, and removal of the stop layer. Selectivity can be controlled to some extent by varying the relative concentrations of the components of the polishing composition.

[0060] 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, in use, has a speed resulting from an orbital, linear, or circular motion during movement, a polishing pad that contacts the platen and moves with the platen during operation, and a carrier that holds a substrate so that the substrate is polished by contacting and moving against the surface of the polishing pad.The substrate is polished by placing the substrate in contact with the polishing pad and the polishing composition of the present invention, and then moving the polishing pad against the substrate to grind at least a portion of the substrate to polish the substrate.

[0061] The substrate can be polished with the chemical mechanical polishing composition using any suitable polishing pad (e.g., polishing surface). Suitable polishing pads include, for example, woven and nonwoven polishing pads. In addition, suitable polishing pads can include any suitable polymer of various density, hardness, thickness, compressibility, ability to rebound when compressed, and compression modulus. Suitable polymers can include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbon, polycarbonate, polyester, polyacrylate, polyether, polyethylene, polyamide, polyurethane, polystyrene, polypropylene, molded products thereof, and mixtures thereof. Soft polyurethane polishing pads are particularly useful in conjunction with the polishing method of the present invention. Exemplary pads include, but are not limited to, SURFIN™ 000, SURFIN™ SSW1, SPM3100 (e.g., commercially available from Eminess Technologies), POLITEX™, and Fujibo POLYPAS™ 27. Particularly preferred polishing pads are EPIC™ D100 pads, NEXPLANAR™ E6088 pads available from Cabot Microelectronics, and IC1010™ pads available from Dow Chemical Company.

[0062] Preferably, the chemical mechanical polishing apparatus further comprises a system for detecting the end point of polishing in situ, 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 disclosed, for example, in U.S. Patent No. 5,196,353, U.S. Patent No. 5,433,651, U.S. Patent No. 5,609,511, U.S. Patent No. 5,643,046, U.S. Patent No. 5,658,183, U.S. Patent No. 5,730,642, U.S. Patent No. 5,838,447, U.S. Patent No. 5,872,633, U.S. Patent No. 5,893,796, U.S. Patent No. 5,949,927, and U.S. Patent No. 5,964,643. Preferably, inspecting or monitoring the progress of the polishing process with respect to the substrate being polished allows for the determination of the end point of polishing, i.e., when to terminate the polishing process with respect to a particular substrate.

[0063] The present invention is further illustrated by the following embodiments.

[0064] Embodiment (1) is a chemical mechanical polishing composition for polishing silicon nitride-containing substrates. The composition includes an aqueous carrier, cationic silica particles dispersed in the aqueous carrier, the cationic silica abrasive particles having a zeta potential of at least 10 mV in the polishing composition, and a polishing additive selected from the group consisting of polyetheramines, polysilamines, polyvinylimidazoles, and combinations thereof, the polyetheramines and polysilamines having a corresponding weight average molecular weight of less than about 1,000 g / mol, and the polishing composition has a pH of greater than about 6.

[0065] Embodiment (2) is the polishing composition according to embodiment (1), wherein the polishing additive comprises polyvinylimidazole.

[0066] Embodiment (3) is the polishing composition of embodiment (1), wherein the polishing additive comprises a polysilamine having a weight average molecular weight of about 900 g / mol or less.

[0067] Embodiment (4) is the polishing composition of embodiment (1), wherein the polishing additive comprises a polyetheramine having a weight average molecular weight of about 900 g / mol or less.

[0068] Embodiment (5) is the polishing composition of embodiment (4), wherein the polyetheramine is a propylene oxide diamine, propylene oxide triamine, ethylene oxide / propylene oxide diamine, ethylene oxide / propylene oxide triamine, or a combination thereof.

[0069] In an embodiment (6), the polyetheramine is of formula (I): [ka]

[0070] In the formula, R is a C1-C6 alkyl group, and x, y, and z are independently an integer of 0 to 15. The polishing composition according to embodiment (5).

[0071] Embodiment (7) is a polishing composition according to any one of embodiments (1) and (3) to (6), in which the polishing additive comprises a polyetheramine having a weight average molecular weight of about 600 g / mol or less, or a polysilamine having a weight average molecular weight of about 600 g / mol or less.

[0072] Embodiment (8) is the polishing composition of any one of embodiments (1) to (7), wherein the polishing additive is present in the polishing composition at a concentration ranging from about 0.01 mM to about 1 mM.

[0073] Embodiment (9) is the polishing composition according to any one of embodiments (1) to (8), wherein the cationic silica abrasive particles have a surface that is treated with a quaternary aminosilane, a dipodal aminosilane, or a combination thereof.

[0074] Embodiment (10) is the polishing composition of any one of embodiments (1) to (9), wherein the cationic silica abrasive particles comprise colloidal silica particles having a permanent positive charge of at least 20 mV at a pH greater than about 6.

[0075] Embodiment (11) is the polishing composition of any one of embodiments (1) to (7), wherein the cationic silica abrasive particles have an average particle size of from about 20 nm to about 80 nm.

[0076] Embodiment (12) is the polishing composition according to any one of embodiments (1) to (11), wherein the polishing composition has a pH of about 6 to about 8.

[0077] Embodiment (13) is the polishing composition of any one of embodiments (1) to (12), wherein the polishing composition has a pH of about 7.

[0078] Embodiment (14) is a method for chemically mechanically polishing a substrate, the method comprising: (a) providing a substrate comprising a silicon nitride (SiN) layer on a surface of the substrate; (b) providing a polishing pad; (c) providing a chemical mechanical polishing composition comprising: (i) an aqueous carrier; (ii) cationic silica particles dispersed in the aqueous carrier, the cationic silica abrasive particles having a zeta potential of at least 10 mV in the polishing composition; (iii) a polishing additive selected from the group consisting of polyetheramines, polysilamines, polyvinylimidazoles, and combinations thereof, the polyetheramines and polysilamines having a corresponding weight average molecular weight of about 1,000 g / mol or less; the polishing composition having a pH greater than about 6; (d) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and (e) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the SiN layer on the surface of the substrate to polish the substrate.

[0079] Embodiment (15) is the method of embodiment (14), wherein the polishing additive comprises polyvinylimidazole.

[0080] Embodiment (16) is the method of embodiment (14), wherein the polishing additive comprises a polysilamine having a weight average molecular weight of about 1,000 g / mol or less.

[0081] Embodiment (17) is the method of embodiment (14), wherein the polishing additive comprises a polyetheramine having a weight average molecular weight of about 1,000 g / mol or less.

[0082] Embodiment (18) is the method of embodiment (17), wherein the polyetheramine is a propylene oxide diamine, a propylene oxide triamine, an ethylene oxide / propylene oxide diamine, an ethylene oxide / propylene oxide triamine, or a combination thereof.

[0083] In an embodiment (19), the polyetheramine is of formula (I): [ka]

[0084] wherein R is a C1-C6 alkyl group, and x, y, and z are independently integers from 0 to 15.

[0085] Embodiment (20) is the method of any one of embodiments (14) and (16)-(19), wherein the polishing additive comprises a polyetheramine having a weight average molecular weight of about 600 g / mol or less, or a polysilamine having a weight average molecular weight of about 600 g / mol or less.

[0086] Embodiment (21) is the method of any one of embodiments (14)-(20), wherein the polishing additive is present in the polishing composition at a concentration ranging from about 0.01 mM to about 1 mM.

[0087] Embodiment (22) is the method of any one of embodiments (14)-(21), wherein the cationic silica abrasive particles have a surface that is treated with a quaternary aminosilane, a dipodal aminosilane, or a combination thereof.

[0088] Embodiment (23) is the method of any one of embodiments (14)-(22), wherein the cationic silica abrasive particles comprise colloidal silica particles having a permanent positive charge of at least 20 mV at a pH greater than about 6.

[0089] Embodiment (24) is the method of any one of embodiments (14) through (23), wherein the cationic silica abrasive particles have an average particle size of from about 20 nm to about 80 nm.

[0090] Embodiment (25) is the method of any one of embodiments (14) to (24), wherein the polishing composition has a pH of about 6 to about 8.

[0091] Embodiment (26) is the method of any one of embodiments (14)-(25), wherein (i) the substrate further comprises a silicon oxide (SiO) layer on a surface of the substrate; (ii) at least a portion of the silicon oxide layer is ground to polish the substrate; and (iii) the grinding of the SiN layer provides a SiN removal rate and the grinding of the SiO layer provides a SiO removal rate such that the ratio of SiN removal rate to SiO removal rate is greater than about 4 to 1. EXAMPLES

[0092] These following examples further illustrate the invention but, of course, should not be construed as in any way limiting its scope.

[0093] The following abbreviations are used throughout the examples: removal rate (RR), tetraethyl orthosilicate (TEOS), and silicon nitride (SiN).

[0094] In the following examples, substrates, TEOS silicon oxide coated on silicon (prepared from tetraethoxysilane), SiN coated on silicon, and patterned wafers obtained from Silyb Inc. were polished using a Logitech2 benchtop polisher with a down force of 1.5 PSI (10.3 kPa). The patterned wafers consisted of 100 μm silicon nitride features on a silicon oxide coated substrate. The same polishing parameters were used for all compositions using a Nexplanar E6088 pad with Saesol C7 (commercially available from Saesol Diamond Ind. Co., Ltd., South Korea) conditioner. Standard Logitech polishing parameters are as follows: Nexplanar E6088 pad, down force = 10.3 kPa (1.5 psi), head speed = 87 rpm, platen speed = 93 rpm, total flow rate = 50 mL / min. The removal rate was calculated by measuring the film thickness using ellipsometry and subtracting the final thickness from the initial thickness.

[0095] Example 1 This example demonstrates the effect of additive type and molecular weight on the selectivity of SiN:TEOS, as measured by silicon nitride removal rate versus silicon oxide removal rate.

[0096] Substrates including TEOS-coated silicon and silicon nitride-coated silicon were polished with sixteen (16) different polishing compositions, Polishing Compositions 1A-1P (Table 1). The substrates were polished with a Logitech 2 benchtop polisher at a down force of 1.5 PSI (10.3 kPa) using a Nexplanar E6088 pad with Saesol C7 conditioner. Each of the polishing compositions contained 0.5 wt. % cationic silica abrasive particles, 2 mM Tris hydrochloride, and 120 ppm biocide at a pH of 7. The cationic colloidal silica particles were prepared as described in Example 7 of U.S. Pat. No. 9,382,450. Each of the polishing compositions further contained the polishing additives in the amounts shown in Table 1.

[0097] Following polishing, the removal rates of TEOS and SiN were measured and the results are shown in Table 1. [Table 1]

[0098] As can be seen from the results in Table 1, polishing compositions 1H-1P, which contained polishing additives having molecular weights less than about 1,000 g / mol, exhibited the greatest SiN:TEOS selectivity. Polishing composition 1N, which contained JEFFAMINE™ T-403, exhibited a SiN:TEOS selectivity of 48:1, nearly 50 times higher than the control.

[0099] Example 2 This example demonstrates the effect of additive concentration on the selectivity of SiN:TEOS as measured by silicon nitride removal rate versus silicon oxide removal rate.

[0100] Substrates including TEOS-coated silicon and silicon nitride-coated silicon were polished with five (5) different polishing compositions, Polishing Compositions 2A-2E (Table 2). The substrates were polished with a Logitech 2 benchtop polisher at a down force of 1.5 PSI (10.3 kPa) using a Nexplanar E6088 pad with Saesol C7 conditioner. Each of the polishing compositions contained 0.5 wt. % cationic silica abrasive particles, 2 mM Tris hydrochloride, and 120 ppm biocide at a pH of 7. Each of the polishing compositions 2B-2E further contained JEFFAMINE™ T-403 in the amount shown in Table 2. Polishing Composition 2A is provided as a control. The cationic colloidal silica particles were prepared as described in Example 7 of U.S. Pat. No. 9,382,450.

[0101] Following polishing, the removal rates of TEOS and SiN were measured and the results are shown in Table 2. [Table 2]

[0102] As can be seen from the results set forth in Table 2, Polishing Compositions 2B-2E containing JEFFAMINE™ T-403 exhibited reduced TEOS removal rates and provided better SiN:TEOS selectivity than the control. Polishing Composition 2C containing 0.1 mM JEFFAMINE™ T-403 exhibited the lowest TEOS removal rate and the highest SiN:TEOS selectivity with a ratio of about 48:1.

[0103] All references cited in this specification, including publications, patent applications, and patents, are herein incorporated by reference to the same extent as if each reference was individually and specifically indicated to be incorporated by reference and was set forth in its entirety herein.

[0104] The use of the terms "a" and "an" and "the" and "at least one" and similar referents in the context of describing the invention (particularly in the context of the claims below) should be construed to encompass both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term "at least one" following a list of one or more items (e.g., "at least one of A and B") should be construed to mean one item selected from the listed items (A or B), or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" should be construed as open-ended terms (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 individually referring to each separate value within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually recited herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by context. Any and all examples provided herein, or the use of exemplary language (e.g., "etc.") are intended merely to further clarify the invention, and do not limit the scope of the invention unless otherwise asserted. No language in this specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0105] Preferred embodiments of the present invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of these preferred embodiments may become apparent to those skilled in the art upon reading the foregoing description. The inventors expect those skilled in the art to employ such variations as appropriate, and the inventors intend for the invention to be carried out otherwise than as specifically described herein. Accordingly, the present invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, the present invention encompasses any combination of the above-described elements in all possible variations thereof unless otherwise indicated herein or clearly contradicted by context. The present invention can be embodied in the following manner. (Appendix 1) 1. A chemical mechanical polishing composition for polishing a silicon nitride-containing substrate, comprising: An aqueous carrier; cationic silica abrasive particles dispersed in the aqueous carrier, the cationic silica abrasive particles having a zeta potential in the polishing composition of at least 10 mV; a polishing additive selected from the group consisting of polyetheramines, polysilamines, polyvinylimidazoles, and combinations thereof, wherein the polyetheramines and the polysilamines have corresponding weight average molecular weights of less than about 1,000 g / mol; The polishing composition has a pH of greater than about 6. (Appendix 2) 2. The polishing composition of claim 1, wherein the polishing additive comprises polyvinylimidazole. (Appendix 3) 2. The polishing composition of claim 1, wherein the polishing additive comprises a polysilamine having a weight average molecular weight of about 900 g / mol or less. (Appendix 4) 2. The polishing composition of claim 1, wherein the polishing additive comprises a polyetheramine having a weight average molecular weight of about 900 g / mol or less. (Appendix 5) 5. The polishing composition of claim 4, wherein the polyetheramine is a propylene oxide diamine, a propylene oxide triamine, an ethylene oxide / propylene oxide diamine, an ethylene oxide / propylene oxide triamine, or a combination thereof. (Appendix 6) The polyetheramine is of formula (I): [ka] In the formula, R is C 1 -C 6 The polishing composition according to claim 5, wherein x, y, and z are independently an integer of 0 to 15. (Appendix 7) 2. The polishing composition of claim 1, wherein the polishing additive comprises a polyetheramine having a weight average molecular weight of about 600 g / mol or less, or a polysilamine having a weight average molecular weight of about 600 g / mol or less. (Appendix 8) 2. The polishing composition of claim 1, wherein the polishing additive is present in the polishing composition at a concentration ranging from about 0.01 mM to about 1 mM. (Appendix 9) 2. The polishing composition of claim 1, wherein the cationic silica abrasive particles have a surface that is treated with a quaternary aminosilane, a dipodal aminosilane, or a combination thereof. (Appendix 10) 2. The polishing composition of claim 1, wherein the cationic silica abrasive particles comprise colloidal silica particles having a permanent positive charge of at least 20 mV at a pH greater than about 6. (Appendix 11) 2. The polishing composition of claim 1, wherein the cationic silica abrasive particles have an average particle size of about 20 nm to about 80 nm. (Appendix 12) 2. The polishing composition of claim 1, wherein the polishing composition has a pH of about 6 to about 8. (Appendix 13) 11. The polishing composition of claim 10, wherein the polishing composition has a pH of about 7. (Appendix 14) 1. A method for chemically mechanically polishing a substrate, comprising: (a) providing a substrate, the substrate comprising a silicon nitride (SiN) layer on a surface of the substrate; (b) providing a polishing pad; (c) providing a chemical-mechanical polishing composition, the chemical-mechanical polishing composition comprising: (i) an aqueous carrier; (ii) cationic silica abrasive particles dispersed in the aqueous carrier, the cationic silica abrasive particles having a zeta potential in the polishing composition of at least 10 mV; (iii) a polishing additive selected from the group consisting of polyetheramines, polysilamines, polyvinylimidazoles, and combinations thereof, wherein the polyetheramines and the polysilamines have corresponding weight average molecular weights of less than about 1,000 g / mol; providing a chemical-mechanical polishing composition, wherein the polishing composition has a pH greater than about 6; (d) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition; (e) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to abrade at least a portion of the SiN layer on a surface of the substrate to polish the substrate. (Appendix 15) 15. The method of claim 14, wherein the polishing additive comprises polyvinylimidazole. (Appendix 16) 15. The method of claim 14, wherein the polishing additive comprises a polysilamine having a weight average molecular weight of about 900 g / mol or less. (Appendix 17) 15. The method of claim 14, wherein the polishing additive comprises a polyetheramine having a weight average molecular weight of about 900 g / mol or less. (Appendix 18) 18. The method of claim 17, wherein the polyetheramine is a propylene oxide diamine, a propylene oxide triamine, an ethylene oxide / propylene oxide diamine, an ethylene oxide / propylene oxide triamine, or a combination thereof. (Appendix 19) The polyetheramine is of formula (I):

change

Claims

1. 1. A chemical-mechanical polishing composition for polishing a silicon nitride-containing substrate, comprising: An aqueous carrier; cationic silica abrasive particles dispersed in the aqueous carrier, the cationic silica abrasive particles having a zeta potential in the chemical mechanical polishing composition of at least 10 mV; Formula (I): 【Chemistry 1】 (Wherein, R is C 1 -C 6 and a polishing additive comprising a polyetheramine having a weight average molecular weight of 500 g / mol or less, the polyetheramine having an alkyl group, x, y, and z being independently an integer from 0 to 15; the polishing additive is present in the chemical-mechanical polishing composition at a concentration ranging from 0.07 mM to 0.25 mM; The chemical-mechanical polishing composition has a pH of 6 to 8.

2. 10. The chemical-mechanical polishing composition of claim 1, wherein the cationic silica abrasive particles have a surface that is treated with a quaternary aminosilane, a dipodal aminosilane, or a combination thereof.

3. 2. The chemical-mechanical polishing composition of claim 1, wherein the cationic silica abrasive particles comprise colloidal silica particles having a permanent positive charge of at least 20 mV at a pH greater than 6.

4. 2. The chemical mechanical polishing composition of claim 1, wherein the cationic silica abrasive particles have an average particle size of 20 nm to 80 nm.

5. The chemical-mechanical polishing composition of claim 3 , wherein the chemical-mechanical polishing composition has a pH of 7.

6. 1. A method for chemically mechanically polishing a substrate, comprising: (a) providing a substrate, the substrate comprising a silicon nitride (SiN) layer on a surface of the substrate; (b) providing a polishing pad; (c) providing a chemical-mechanical polishing composition, the chemical-mechanical polishing composition comprising: (i) an aqueous carrier; (ii) cationic silica abrasive particles dispersed in the aqueous carrier, the cationic silica abrasive particles having a zeta potential in the chemical-mechanical polishing composition of at least 10 mV; (iii) Formula (I): 【Chemistry 2】 (Wherein, R is C 1 -C 6 wherein x, y, and z are independently integers from 0 to 15; and Including, the polishing additive is present in the chemical-mechanical polishing composition at a concentration ranging from 0.07 mM to 0.25 mM; providing a chemical-mechanical polishing composition having a pH of 6 to 8; (d) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition; (e) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to abrade at least a portion of the SiN layer on a surface of the substrate to polish the substrate.

7. 7. The method of claim 6, wherein the cationic silica abrasive particles have a surface that is treated with a quaternary aminosilane, a dipodal aminosilane, or a combination thereof.

8. 7. The method of claim 6, wherein the cationic silica abrasive particles comprise colloidal silica particles having a permanent positive charge of at least 20 mV at a pH greater than 6.

9. The method of claim 6, wherein the cationic silica abrasive particles have an average particle size of 20 nm to 80 nm.

10. the substrate further comprises a silicon oxide (SiO) layer on a surface of the substrate; grinding away at least a portion of the SiO layer to polish the substrate; 7. The method of claim 6, wherein the grinding of the SiN layer provides a SiN removal rate and the grinding of the SiO layer provides a SiO removal rate such that a ratio of the SiN removal rate to the SiO removal rate is greater than 4 to 1.

Images