Chemical mechanical polishing composition for polishing silicon carbide substrate and polishing method thereof

Abstract

The invention provides a chemical mechanical polishing composition for polishing a silicon carbide substrate and a polishing method thereof. Wherein the chemical mechanical polishing composition comprises silicon oxide abrasive particles, a first salt, a second salt, a catalyst and an oxidizing agent, and the first salt comprises a sulfur salt. When the chemical mechanical polishing composition is used for polishing the silicon carbide substrate, the chemical environment in the chemical mechanical polishing composition can be kept stable, so that the material removal rate of the chemical mechanical polishing composition on the silicon carbide substrate is increased.

Description

Technical Field

[0001] This application relates to the field of chemical technology, and in particular to a chemical mechanical polishing composition for polishing silicon carbide substrates and a polishing method thereof. Background Technology

[0002] In semiconductor manufacturing processes, chemical mechanical polishing (CMP) of silicon carbide substrates is a crucial step to ensure the flatness and smoothness of the substrate surface. CMP technology polishes the substrate using a chemical mechanical polishing composition (hereinafter referred to as the composition). To comply with environmental requirements and reduce production costs, the recycling of the composition is often considered during the CMP process. However, with repeated use of the composition, it is difficult to maintain a stable chemical environment within it, and abrasive particles may lose their original polishing effect due to aggregation or morphological changes, leading to a decrease in substrate removal rate.

[0003] Therefore, improving the composition to enhance its substrate removal efficiency is an issue that needs to be addressed. Summary of the Invention

[0004] This application provides a chemical mechanical polishing composition and a polishing method for polishing silicon carbide substrates, wherein a first salt and a second salt are added to the composition. This allows the first and second salts to work together, thereby maintaining the stability of the components in the composition during recycling and improving the removal rate of the silicon carbide substrate.

[0005] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0006] In a first aspect, embodiments of this application provide a chemical mechanical polishing composition for polishing silicon carbide substrates, comprising silicon oxide abrasive grains, a first salt, a second salt, a catalyst, and an oxidant, wherein the first salt comprises a sulfur salt.

[0007] According to some embodiments of this application, the silicon oxide abrasive grains include first silicon oxide abrasive grains with a grain size span of at least 0.5; and second silicon oxide abrasive grains with a grain size span of at least 0.4.

[0008] According to some embodiments of this application, the silicon oxide abrasive includes a first silicon oxide abrasive and a second silicon oxide abrasive, wherein the Z-average particle size of the second silicon oxide abrasive is at least 1.6 times the Z-average particle size of the first silicon oxide abrasive.

[0009] According to some embodiments of this application, the sulfur salt includes at least one of thiosulfate, sulfite, or bisulfite.

[0010] According to some embodiments of this application, the second salt includes a nitrogen salt.

[0011] According to some embodiments of this application, the nitrogen salt includes at least one of nitrate, nitrite, or nitride salt.

[0012] According to some embodiments of this application, the catalyst comprises vanadate.

[0013] According to some embodiments of this application, the composition has a pH value of 5-7.

[0014] According to some embodiments of this application, the silica abrasive particles have a zeta potential of at least -8 mV at a pH of 5 to 7 in the composition.

[0015] Secondly, embodiments of this application provide a polishing method for a silicon carbide substrate, wherein the method utilizes the composition described in any one of the first aspects above to polish the silicon carbide substrate.

[0016] In summary, this application provides a chemical mechanical polishing composition and a polishing method for polishing silicon carbide substrates. The chemical mechanical polishing composition includes a first salt, a second salt, a catalyst, and an oxidant. The first salt includes a sulfur salt. By adding a sulfur salt to the chemical mechanical polishing composition, the sulfur salt and oxidant interact, maintaining the stability of the chemical environment within the composition and enhancing the activity of the catalyst, thereby improving the material removal rate of the composition on the silicon carbide substrate. Detailed Implementation

[0017] The following description provides specific application scenarios and requirements for this specification, intended to enable those skilled in the art to make and use the contents of this specification. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0018] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not restrictive. For example, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” used herein may also include the plural forms. When used in this specification, the terms “comprising,” “including,” and / or “containing” mean that the associated integers, steps, operations, elements, and / or components are present, but do not exclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups, or that other features, integers, steps, operations, elements, components, and / or groups may be added to the system / method.

[0019] In this application, "X includes at least one of A, B, or C" means that X includes at least A, or X includes at least B, or X includes at least C. That is, X can include any combination of A, B, and C, or any combination of A, B, and C, as well as other possible content / elements. The arbitrary combination of A, B, and C can be A, B, C, AB, AC, BC, or ABC.

[0020] In chemical mechanical polishing (CMP), traditional polishing slurries rely primarily on abrasive grains and polishing aids to achieve efficient polishing of materials such as silicon carbide substrates. Typically, the polishing aids do not specifically include a primary and secondary salt. Traditional polishing slurries, through the synergistic effect of mechanical abrasion and chemical reaction, meet the planarization requirements to a certain extent. However, after repeated use, the chemical environment within the traditional polishing slurry is difficult to stabilize; for example, the pH value may not remain stable, and abrasive grains may easily agglomerate. These unstable factors affect the removal rate of the polishing slurry on the silicon carbide substrate.

[0021] In view of this, some embodiments of this application provide a chemical mechanical polishing composition and polishing method for polishing silicon carbide substrates, incorporating a first salt and a second salt into the composition. The first salt reacts with an oxidant to generate an acid, thereby ensuring that the pH value of the composition remains stable during cycling. Simultaneously, the second salt optimizes the charge distribution on the surface of the abrasive particles, enhancing the mechanical removal capability of the abrasive particles.

[0022] Before describing the specific embodiments in this specification, the application scenarios of this specification will be introduced as follows.

[0023] The compositions provided in this specification can be used for polishing silicon carbide substrates, including but not limited to those for silicon carbide substrates. Specifically, the compositions provided in this specification can be used for polishing silicon carbide substrates, such as 4H-silicon carbide or 6H-silicon carbide. The following description uses the use of the compositions for polishing silicon carbide substrates as an example.

[0024] The compositions of this invention are used for chemical mechanical polishing of silicon carbide substrates. These compositions can be used for surface polishing of silicon carbide wafers, such as coarse polishing and fine polishing. In some embodiments, the compositions according to this invention are used for fine polishing of silicon carbide wafers. In some embodiments, the silicon carbide may be undoped silicon carbide or doped silicon carbide. In specific embodiments, the silicon carbide may further comprise oxides of aluminum, iron, and calcium.

[0025] The composition includes silica abrasive grains. The silica abrasive grains provide a mechanical abrasive action, removing minute protrusions and uneven portions of the silicon carbide substrate surface through physical friction. The silica abrasive grains are silica abrasive grains. The silica abrasive grains include colloidal silica abrasive grains, i.e., silica prepared by hydrolysis or sol-gel methods. The colloidal silica can be obtained by wet processes, such as precipitation (precipitated silica), polycondensation, or similar processes. In some embodiments, the silica abrasive grains include fumed silica abrasive grains, i.e., silica prepared by pyrolysis or flame hydrolysis. In some embodiments, the silica abrasive grains include at least one of fumed silica abrasive grains, colloidal silica abrasive grains, or fumed silica abrasive grains.

[0026] According to some embodiments of this application, the weight ratio of silica abrasive particles in the composition is between 20-45 wt%. In some embodiments, the weight ratio of silica abrasive particles in the composition is between 20-30 wt%. In some embodiments, the weight ratio of silica abrasive particles in the composition is between 30-35 wt%. Further, the weight ratio of silica abrasive particles in the composition can be selected as 20 wt%-21 wt%, 21 wt%-22 wt%, 22 wt%-23 wt%, 23 wt%-24 wt%, 24 wt%-25 wt%, 25 wt%-26 wt%, 26 wt%-27 wt%, 27 wt%-28 wt%, 28 wt%-29 wt%, 29 wt%-30 wt%, 30 wt%-31 wt%, 31 wt%- Between 32wt%, 32wt%-33wt%, 33wt%-34wt%, 34wt%-35wt%, 35wt%-36wt%, 36wt%-37wt%, 37wt%-38wt%, 38wt%-39wt%, 39wt%-40wt%, 40wt%-41wt%, 41wt%-42wt%, 42wt%-43wt%, 43wt%-44wt%, or 44wt%-45wt%.

[0027] According to other embodiments of this application, the weight ratio of silica abrasive particles in the composition can also be selected in the range of 10-20 wt%. For example, depending on the requirements of different grinding efficiency and grinding quality, in some embodiments, the weight ratio of silica abrasive particles in the composition can also be selected in the range of 15-20 wt%. Further, the weight ratio of silica abrasive particles in the composition can be selected to be between 10 wt%-11 wt%, 11 wt%-12 wt%, 12 wt%-13 wt%, 13 wt%-14 wt%, 14 wt%-15 wt%, 15 wt%-16 wt%, 16 wt%-17 wt%, 17 wt%-18 wt%, 18 wt%-19 wt%, or 19 wt%-20 wt%.

[0028] Silica abrasive grains have a spherical morphology. This spherical morphology is not limited to perfect spheres; for example, abrasive grains that are generally spherical, elliptical, or have a grape-like structure can all be referred to as having a spherical morphology in this application. The spherical morphology can be determined by those skilled in the art, for example, using images from a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

[0029] The particle size distribution of silica abrasive grains also affects the removal rate of silicon carbide substrates. A wider particle size distribution of silica abrasive grains results in a higher material removal rate because larger silica abrasive grains can provide stronger mechanical cutting forces, quickly removing larger defects on the material surface, while smaller silica abrasive grains can penetrate micro-pits for fine polishing and promote chemical reactions, thereby synergistically improving the overall material removal rate. The width of the silica abrasive grain size distribution can be described by the grain size span. The grain size span of silica abrasive grains refers to the value obtained by the formula (D90-D10) / D50. According to some embodiments of this application, the grain size span of silica abrasive grains is greater than 0.9; for example, the grain size span of silica abrasive grains can be 1.0, 1.1, 1.2, or 1.3, or a grain size span between any of the above values. It is understood that the particle size distribution of silica abrasive grains can be obtained by dynamic light scattering measurement (e.g., using a Malvern MastersizerS from Malvern Instruments). Wherein, D10 is the particle size of 10 vol% silica abrasive particles smaller than this value. D50 is the particle size of 50 vol% silica abrasive particles smaller than this value. D90 is the particle size of 90 vol% silica abrasive particles smaller than this value.

[0030] It should be noted that the particle size span, z-average particle size, D10, D50 and D90 described here refer to the particle size of the silica abrasive particles in the composition.

[0031] Silica abrasives can include single abrasives with the same particle size range, or mixed abrasives with different particle size ranges.

[0032] In some embodiments, the silica abrasive grains are single abrasive grains with the same grain size span. The grain size span of the single-size silica abrasive grains is greater than 0.9, for example, 1.0, 1.1, 1.2, or 1.3, and a grain size span between any of the above values.

[0033] The z-average particle size can be further measured by dynamic light scattering, for example using a Zetasizer Nano ZSE (Malvern Instruments Ltd.); the z-average particle size refers to the intensity-weighted average hydrodynamic size of a particle ensemble measured by dynamic light scattering (e.g., using a Zetasizer Nano ZSE (Malvern Instruments Ltd.)). Specifically, the silica abrasive particles with a single particle size distribution have a z-average particle size of 50-150 nm as measured by dynamic light scattering. In some embodiments, the silica abrasive particles with a single particle size distribution have a z-average particle size of 60-140 nm as measured by dynamic light scattering. In some embodiments, the silica abrasive particles with a single particle size distribution have a z-average particle size of 70-130 nm as measured by dynamic light scattering. In some embodiments, the silica abrasive particles with a single particle size distribution have a z-average particle size of 80-120 nm as measured by dynamic light scattering. Further, the silica abrasive particles have a z-average particle size of 5 nm as measured by dynamic light scattering. Z-average particle size between 0nm-55nm, 55nm-60nm, 60nm-65nm, 65nm-70nm, 70nm-75nm, 75nm-80nm, 80nm-85nm, 85nm-90nm, 90nm-95nm, 95nm-100nm, 100nm-105nm, 105nm-110nm, 110nm-115nm, 115nm-120nm, 120nm-125nm, 125nm-130nm, 130nm-135nm, 135nm-140nm, 140nm-145nm, or 145nm-150nm.

[0034] Furthermore, the aforementioned silicon oxide abrasive grains with a single particle size distribution may also have a D10 in the range of 10-70 nm as measured by dynamic light scattering. In some embodiments, the silicon oxide abrasive grains with a single particle size distribution may also have a D10 in the range of 20-60 nm as measured by dynamic light scattering. The silicon oxide abrasive grains with a single particle size distribution may also have a D10 in the range of 30-50 nm as measured by dynamic light scattering. Even further, the silicon oxide abrasive grains may have a D10 in the range of 10 nm-15 nm, 15 nm-20 nm, 20 nm-25 nm, 25 nm-30 nm, 30 nm-35 nm, 35 nm-40 nm, 40 nm-45 nm, 45 nm-50 nm, 50 nm-55 nm, 55 nm-60 nm, 60 nm-65 nm, or 65 nm-70 nm as measured by dynamic light scattering.

[0035] Silica abrasive grains with a single particle size distribution have a D50 in the dynamic light scattering measurement range of 30-120 nm. In some embodiments, silica abrasive grains with a single particle size distribution have a D50 in the dynamic light scattering measurement range of 40-110 nm. In some embodiments, silica abrasive grains with a single particle size distribution have a D50 in the dynamic light scattering measurement range of 50-100 nm. In some embodiments, silica abrasive grains with a single particle size distribution have a D50 in the dynamic light scattering measurement range of 50-90 nm. Furthermore, the silicon oxide abrasive grains have a D50 that is dynamically measured to be between 30nm-35nm, 35nm-40nm, 40nm-45nm, 45nm-50nm, 50nm-55nm, 55nm-60nm, 60nm-65nm, 65nm-70nm, 70nm-75nm, 75nm-80nm, 80nm-85nm, 85nm-90nm, 90nm-95nm, 95nm-100nm, 100nm-105nm, 105nm-110nm, 110nm-115nm, or 115nm-120nm.

[0036] Silica abrasive grains with a single particle size distribution have a D90 in the dynamic light scattering measurement range of 80-200 nm. In some embodiments, silica abrasive grains with a single particle size distribution have a D90 in the dynamic light scattering measurement range of 90-190 nm. In some embodiments, silica abrasive grains with a single particle size distribution have a D90 in the dynamic light scattering measurement range of 100-180 nm. In some embodiments, silica abrasive grains with a single particle size distribution have a D90 in the dynamic light scattering measurement range of 110-170 nm. In some embodiments, silica abrasive grains with a single particle size distribution have a D90 in the dynamic light scattering measurement range of 110-160 nm. Furthermore, the silicon oxide abrasive grains have dynamic light scattering measurements at 80nm-85nm, 85nm-90nm, 90nm-95nm, 95nm-100nm, 100nm-105nm, 105nm-110nm, 110nm-115nm, 115nm-120nm, 120nm-125nm, 125nm-130nm, 130nm-135nm, and 135nm-1 D90 between 40nm, 140nm-145nm, 145nm-150nm, 150nm-155nm, 155nm-160nm, 160nm-165nm, 165nm-170nm, 170nm-175nm, 175nm-180nm, 180nm-185nm, 185nm-190nm, 190nm-195nm, or 195nm-200nm.

[0037] In some embodiments, the silica abrasive particles are a mixture of particles with different particle size ranges. The mixed abrasive particles can be a mixture of N silica abrasive particles with different particle size ranges. Here, N is an integer greater than 2, such as 2, 3, 4, 5, etc. When the silica abrasive particles are a mixture of two silica abrasive particles with different particle size ranges, the particle size span of the mixed abrasive particles after mixing the first silica abrasive particle and the second silica abrasive particle is greater than 0.9, for example, 1.0, 1.1, 1.2, or 1.3, or a particle size span between any of the above values. It is understood that the Z-average particle size, D10, D50, and D90 of the mixed abrasive particles after mixing the first silica abrasive particle and the second silica abrasive particle are the same as those of the single abrasive particles described above, and will not be repeated here.

[0038] The particle size range of the first silicon oxide abrasive is at least 0.5. For example, the particle size range of the first silicon oxide abrasive can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, or 1.5, as well as a particle size range between any of the above values.

[0039] The first silica abrasive grain has a Z-average particle size of 30-70 nm as measured by dynamic light scattering. Specifically, the first silica abrasive grain has a Z-average particle size between 30 nm-35 nm, 35 nm-40 nm, 40 nm-45 nm, 45 nm-50 nm, 50 nm-55 nm, 55 nm-60 nm, 60 nm-65 nm, or 65 nm-70 nm as measured by dynamic light scattering.

[0040] Further, the first silica abrasive grain has a D10 in the dynamic light scattering measurement range of 10-75 nm. In some embodiments, the first silica abrasive grain has a D10 in the dynamic light scattering measurement range of 15-70 nm. In some embodiments, the first silica abrasive grain has a D10 in the dynamic light scattering measurement range of 20-65 nm. In some embodiments, the first silica abrasive grain has a D10 in the dynamic light scattering measurement range of 25-60 nm. Even further, the first silica abrasive grain has a D10 in the dynamic light scattering measurement range of 10 nm-15 nm, 15 nm-20 nm, 20 nm-25 nm, 25 nm-30 nm, 30 nm-35 nm, 35 nm-40 nm, 40 nm-45 nm, 45 nm-50 nm, 50 nm-55 nm, 55 nm-60 nm, 60 nm-65 nm, 65 nm-70 nm, or 70 nm-75 nm.

[0041] The first silica abrasive grain has a D50 in the dynamic light scattering measurement range of 20-90 nm. In some embodiments, the first silica abrasive grain has a D50 in the dynamic light scattering measurement range of 30-80 nm. In some embodiments, the first silica abrasive grain has a D50 in the dynamic light scattering measurement range of 30-70 nm. Further, the first silica abrasive grain has a D50 in the dynamic light scattering measurement range of 20 nm-25 nm, 25 nm-30 nm, 30 nm-35 nm, 35 nm-40 nm, 40 nm-45 nm, 45 nm-50 nm, 50 nm-55 nm, 55 nm-60 nm, 60 nm-65 nm, 65 nm-70 nm, 70 nm-75 nm, 75 nm-80 nm, 80 nm-85 nm, or 85 nm-90 nm.

[0042] The first silica abrasive grain has a D90 in the dynamic light scattering measurement range of 35-120 nm. In some embodiments, the first silica abrasive grain has a D90 in the dynamic light scattering measurement range of 40-110 nm. In some embodiments, the first silica abrasive grain has a D90 in the dynamic light scattering measurement range of 50-100 nm. In some embodiments, the first silica abrasive grain has a D90 in the dynamic light scattering measurement range of 50-90 nm. Furthermore, the first silicon oxide abrasive grain has a D90 that can be dynamically measured as being between 35nm-40nm, 40nm-45nm, 45nm-50nm, 50nm-55nm, 55nm-60nm, 60nm-65nm, 65nm-70nm, 70nm-75nm, 75nm-80nm, 80nm-85nm, 85nm-90nm, 90nm-95nm, 95nm-100nm, 100nm-105nm, 105nm-110nm, 110nm-115nm, or 115nm-120nm.

[0043] The particle size range of the second silica abrasive grains is at least 0.4. Specifically, the particle size range of the second silica abrasive grains can be 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5, etc., as well as particle size ranges between any of the above values.

[0044] The Z-average particle size of the second silica abrasive grain is at least 1.6, 1.7, 1.8, 1.9, 2, 2.1 or 2.2 times that of the Z-average particle size of the first silica abrasive grain.

[0045] Specifically, the second silica abrasive grains have a Z-average particle size of 90-150 nm as measured by dynamic light scattering. In some embodiments, the second silica abrasive grains have a Z-average particle size of 100-140 nm as measured by dynamic light scattering. In some embodiments, the second silica abrasive grains have a Z-average particle size of 100-130 nm as measured by dynamic light scattering. Further, the second silica abrasive grains have a Z-average particle size between 90 nm-95 nm, 95 nm-100 nm, 100 nm-105 nm, 105 nm-110 nm, 110 nm-115 nm, 115 nm-120 nm, 120 nm-125 nm, 125 nm-130 nm, 130 nm-135 nm, 135 nm-140 nm, 140 nm-145 nm, or 145 nm-150 nm as measured by dynamic light scattering.

[0046] Further, the second silica abrasive grain has a D10 in the dynamic light scattering measurement range of 40-120 nm. In some embodiments, the second silica abrasive grain has a D10 in the dynamic light scattering measurement range of 50-110 nm. In some embodiments, the second silica abrasive grain has a D10 in the dynamic light scattering measurement range of 60-100 nm. In some embodiments, the second silica abrasive grain has a D10 in the dynamic light scattering measurement range of 60-90 nm. Furthermore, the second silica abrasive grain has a D10 that is dynamically measured to be between 40nm-45nm, 45nm-50nm, 50nm-55nm, 55nm-60nm, 60nm-65nm, 65nm-70nm, 70nm-75nm, 75nm-80nm, 80nm-85nm, 85nm-90nm, 90nm-95nm, 95nm-100nm, 100nm-105nm, 105nm-110nm, 110nm-115nm, or 115nm-120nm.

[0047] The second silica abrasive grain has a D50 in the dynamic light scattering measurement range of 65-150 nm. In some embodiments, the second silica abrasive grain has a D50 in the dynamic light scattering measurement range of 75-140 nm. In some embodiments, the second silica abrasive grain has a D50 in the dynamic light scattering measurement range of 85-130 nm. In some embodiments, the second silica abrasive grain has a D50 in the dynamic light scattering measurement range of 95-120 nm. Furthermore, the second silica abrasive grain has a D50 with dynamic light scattering measured between 65nm-70nm, 70nm-75nm, 75nm-80nm, 80nm-85nm, 85nm-90nm, 90nm-95nm, 95nm-100nm, 100nm-105nm, 105nm-110nm, 110nm-115nm, 115nm-120nm, 120nm-125nm, 125nm-130nm, 130nm-135nm, 135nm-140nm, 140nm-145nm, or 145nm-150nm.

[0048] The second silica abrasive grain has a D90 in the dynamic light scattering measurement range of 100-200 nm. In some embodiments, the second silica abrasive grain has a D90 in the dynamic light scattering measurement range of 110-190 nm. In some embodiments, the second silica abrasive grain has a D90 in the dynamic light scattering measurement range of 120-180 nm. In some embodiments, the second silica abrasive grain has a D90 in the dynamic light scattering measurement range of 130-170 nm. In some embodiments, the second silica abrasive grain has a D90 in the dynamic light scattering measurement range of 130-160 nm. Furthermore, the second silica abrasive grain has a D90 with dynamic light scattering measured between 100nm-105nm, 105nm-110nm, 110nm-115nm, 115nm-120nm, 120nm-125nm, 125nm-130nm, 130nm-135nm, 135nm-140nm, 140nm-145nm, 145nm-150nm, 150nm-155nm, 155nm-160nm, 160nm-165nm, 165nm-170nm, 170nm-175nm, 175nm-180nm, 180nm-185nm, 185nm-190nm, 190nm-195nm, or 195nm-200nm.

[0049] In the mixed abrasive particles, first silica abrasive particles and second silica abrasive particles are mixed in a certain proportion. Further, the ratio of the first silica abrasive particles to the second silica abrasive particles in the mixed abrasive particles is from 3:1 to 1:1. For example, the ratio of the first silica abrasive particles to the second silica abrasive particles is 3:1, 2:1, or 1:1. In some embodiments, the ratio of the first silica abrasive particles to the second silica abrasive particles in the mixed abrasive particles is from 5:1 to 0.2:1. For example, the ratio of the first silica abrasive particles to the second silica abrasive particles is 5:1, 4:1, 3:1, 2:1, 1:1, 0.8:1, 0.6:1, 0.4:1, or 0.2:1.

[0050] It should be noted that the silica abrasive grains may contain impurities. These impurities originate from the raw materials or processes used to prepare the abrasive grains. These impurities can be considered as not being part of the mixed silica abrasive grains; that is, they are not added to the composition as a single component. This means that the impurities are not added by weight.

[0051] The silica abrasive grains are negatively charged. The charge refers to the zeta potential, which can be measured, for example, using a Mastersizer S (Malvern Instruments) method. As known to those skilled in the art, the zeta potential is the potential at the interface between the moving fluid within the composition and the fluid-stabilized layer attached to the abrasive grains dispersed in the composition. The higher the absolute value of the zeta potential, the stronger the electrostatic repulsion between the particles, and therefore the higher the dispersion stability of the particles in the composition. In this embodiment, the silica abrasive grains have a zeta potential of at least -8 mV in the composition at a pH of 5 to 7. Further, the silica abrasive grains have a zeta potential in the composition between -8 mV and -10 mV, -10 mV and -15 mV, -15 mV and -20 mV, -20 mV and -25 mV, -25 mV and -30 mV, -30 mV and -35 mV, or -35 mV and -40 mV at a pH of 5 to 7.

[0052] The composition further includes one or more chemical additives. These chemical additives can interact with abrasive particles and / or with the substrate and / or with the polishing pad during the CMP process. This interaction can be based on, for example, hydrogen bonds, van der Waals forces, electrostatic forces, etc. The chemical additives can be any component suitable for use as, for example, a removal rate promoter, a polishing rate inhibitor, a surfactant, a thickener, a regulator, a complexing agent, a chelating agent, a biocide, a dispersant, an oxidizing agent, a film-forming agent, an etching inhibitor, a catalyst, a terminating compound, a dissolution inhibitor, or a combination thereof.

[0053] The composition also includes a liquid carrier, a first salt, a second salt, a catalyst, and an oxidant. During the CMP process, the first salt and the oxidant work synergistically to improve the removal rate of silicon carbide substrate by silicon oxide abrasive particles. Specifically, the first salt and the oxidant react to generate acidic substances, which helps maintain the chemical environment of the polishing slurry, thereby keeping the catalyst activity of the composition within an optimal range. In some embodiments, the composition may also include at least one of a buffer, a polymer, a surfactant, or a pH adjuster.

[0054] The liquid carrier can contain other components in the composition besides the liquid carrier itself, such as the silica abrasive grains, the first salt, the second salt, the catalyst, the oxidant, the pH adjuster, the buffer, the polymer, the surfactant, etc., to suspend these components in the liquid carrier and allow them to contact the silicon carbide substrate for polishing. The liquid carrier can be an aqueous carrier, or any component suitable for suspending silica abrasive grains and chemical additives. The liquid carrier can be one of water, ethers (such as tetrahydrofuran), or alcohols (such as methanol and ethanol), or a combination of water, ethers (such as dioxane and tetrahydrofuran), and alcohols (such as methanol and ethanol). When the liquid carrier is a combination of multiple components, it contains at least 50 wt% water, for example, the aqueous carrier contains 50 wt%, 70 wt%, 90 wt%, 95 wt%, or 99 wt% water. Further, the water is deionized water.

[0055] Oxidants can react with the surface of silicon carbide substrates and promote material removal during CMP processing, thereby enhancing the material removal rate. Oxidants include inorganic peroxides and / or organic peroxides. Inorganic peroxides consist of two hydrogen atoms and two oxygen atoms. Inorganic peroxides may include hydrogen peroxide, percarbonates, monopersulfates, dipersulfates, persulfates, sodium peroxide, urea peroxide, perchlorate, periodic acid, periodate, perbromic acid, perbromate, perboric acid, perborate, permanganate, bromate, chlorate, chromate, iodate, nitrates, and combinations thereof. Organic peroxides are organic compounds containing a peroxy bond (-OO-). Organic peroxides may include benzoyl peroxide, peracetic acid, di-tert-butyl peroxide, and combinations thereof. In some embodiments, the oxidant is hydrogen peroxide. The following description uses hydrogen peroxide as an example of an oxidant. It should be noted that the oxidizing agent can be used in any available form, such as an acid, conjugate acid, conjugate base, salt (such as potassium salt, sodium salt, ammonium salt, etc.), or a combination thereof. The salt can be any suitable salt, such as potassium salt, sodium salt, ammonium salt, for example, permanganate can be any salt, such as potassium permanganate, sodium permanganate, etc.

[0056] When used, the composition includes 0.5-10 wt% of an oxidizing agent. In some embodiments, the composition includes 1-9 wt% of an oxidizing agent. In some embodiments, the composition includes 1-6 wt% of an oxidizing agent. Further, the composition includes an oxidant in amounts between 0.5wt%-1wt%, 1wt%-1.5wt%, 1.5wt%-2wt%, 2wt%-2.5wt%, 2.5wt%-3wt%, 3wt%-3.5wt%, 3.5wt%-4wt%, 4wt%-4.5wt%, 4.5wt%-5wt%, 5wt%-5.5wt%, 5.5wt%-6wt%, 6wt%-6.5wt%, 6.5wt%-7wt%, 7wt%-7.5wt%, 7.5wt%-8wt%, 8wt%-8.5wt%, 8.5wt%-9wt%, 9wt%-9.5wt%, or 9.5wt%-10wt%.

[0057] Catalysts can collaborate with oxidants to improve the material removal rate of polished silicon carbide substrates. Specifically, the catalyst includes vanadates. The oxidant is hydrogen peroxide. Vanadates are generated by the electrolytic dissociation of vanadate ions. Vanadate ions can coordinate with hydrogen peroxide to form metastable hydrogen peroxide-metal complex ions. These hydrogen peroxide-metal complex ions further promote the oxidative cleavage of Si-C bonds on the silicon carbide substrate surface, thereby significantly improving the material removal rate.

[0058] Vanadates can include, but are not limited to, sodium vanadate (Na3VO4), sodium metavanadate (NaVO3), ammonium metavanadate (NH4VO3), potassium vanadate (K3VO4), and polyvanadates (VO2). x (OH) y Or (VO2) x (O) y ) and magnesium vanadate (MgVO4).

[0059] When used, the composition comprises 0.1-6 wt% vanadate. In some embodiments, the composition comprises 0.2-5.5 wt% vanadate. Further, the composition comprises vanadate in amounts between 0.1 wt%-0.5 wt%, 0.5 wt%-1 wt%, 1 wt%-1.5 wt%, 1.5 wt%-2 wt%, 2 wt%-2.5 wt%, 2.5 wt%-3 wt%, 3 wt%-3.5 wt%, 3.5 wt%-4 wt%, 4 wt%-4.5 wt%, 4.5 wt%-5 wt%, 5 wt%-5.5 wt%, or 5.5 wt%-6 wt%.

[0060] It should be noted that in some embodiments, the composition contains a catalyst (vanadate) to improve the material removal rate. In some embodiments, the composition may not contain a catalyst (vanadate) to reduce defects such as scratches. The specific choice can be made according to the experimental design, and will not be elaborated here.

[0061] While increasing vanadate concentration can improve the material handling of silicon carbide substrates to some extent, excessively high vanadate concentrations may lead to agglomeration of silicon oxide abrasive particles. These factors limit the amount of vanadate added to the composition. To further improve material removal efficiency, salt can be added. The salt may include a first salt and a second salt.

[0062] First salts can react with oxidizing agents to form acids, thus adjusting the pH of the composition. A first salt is a compound that can donate electrons. First salts can also be used as reducing agents in chemical reactions; that is, they can reduce certain components of other substances from a higher oxidation state to a lower oxidation state while being oxidized themselves. First salts contain elements or groups that readily lose electrons, such as sulfide ions (S). 2- ), sulfite (SO3) 2- In other words, the first salt includes sulfites. Sulfites can include at least one of thiosulfates, sulfites, or bisulfites. Thiosulfates, in particular, contain thiosulfate ions (S₂O₃). 2- Compounds containing sulfite ions (SO₄²⁻). Thiosulfates can include, but are not limited to, sodium thiosulfate (Na₂S₂O₃), potassium thiosulfate (K₂S₂O₃), ammonium thiosulfate ((NH₄)₂S₂O₃), magnesium thiosulfate (MgS₂O₃), and aluminum thiosulfate (Al₂(S₂O₃)₃). Sulfites are compounds containing sulfite ions (SO₄²⁻). 2 Compounds containing the ion (-). Sulfites can include, but are not limited to, sodium sulfite (Na₂SO₃), potassium sulfite (K₂SO₃), ammonium sulfite ((NH₄)₂SO₃), sodium dithionite (Na₂S₂O₄), and sodium metabisulfite (Na₂S₂O₅). Bisulfites are compounds containing the bisulfite ion (HSO₃⁻).- Compounds of ). Bisulfites may include, but are not limited to, sodium metabisulfite (NaHSO3), potassium metabisulfite (KHSO3), and ammonium metabisulfite ((NH4)HSO3).

[0063] The second salt can adjust the charge distribution on the particle surface, reduce electrostatic repulsion between the grinding particles and the polished surface, and increase the mechanical removal force of the grinding particles. The second salt refers to a compound that can provide ionic conductivity in a dissolved state. When dissolved, the second salt dissociates into positive and negative ions, thereby giving the composition conductivity. The second salt may include a nitrogen salt. The nitrogen salt includes at least one of nitrates, nitrites, or nitrides. Nitrates refer to salts containing nitrate ions (NO3). - Nitrates are compounds containing nitrite ions (NO₃). Nitrates can include, but are not limited to, sodium nitrate (NaNO₃), potassium nitrate (KNO₃), calcium nitrate (Ca(NO₃)₂), magnesium nitrate (Mg(NO₃)₂), and ammonium nitrate (NH₄NO₃). Nitrites refer to compounds containing nitrite ions (NO₂). - Nitrites are compounds containing, but are not limited to, sodium nitrite (NaNO2), potassium nitrite (KNO2), calcium nitrite (Ca(NO2)2), magnesium nitrite (Mg(NO2)2), and ammonium nitrite (NH4NO2). Nitride salts refer to compounds containing nitride ions (such as NH2). - NH4 + CN - Nitrogen compounds are compounds formed by the direct bonding of nitrogen atoms with metals, etc. Nitrogen salts include, but are not limited to, ammonium salts, amine compounds, and imine compounds. Ammonium salts may include ammonium chloride (NH4Cl), ammonium nitrate (NH4NO3), and ammonium sulfate ((NH4)2SO4). Amine compounds may include ethylenediamine (C2H8N2) and triethanolamine (TEA, C6H2O). 15 NO3). Imine compounds can include hexamethylenediamine (HMDA, C6H). 16 N2).

[0064] In some embodiments, the composition comprises 0.01-3 wt% of a first salt and / or a second salt. Specifically, when the composition comprises both a first salt and a second salt, the composition comprises 0.01-3 wt% of both the first salt and the second salt, i.e., the first salt and the second salt together account for 0.01-3 wt% of the composition. When the composition comprises only the first salt, the composition comprises 0.01-3 wt% of the first salt, i.e., the first salt accounts for 0.01-3 wt% of the composition. When the composition comprises only the second salt, the composition comprises only the second salt, i.e., the composition comprises 0.01-3 wt% of the second salt.

[0065] In some embodiments, the composition comprises 0.02-2.8 wt% of a first salt and / or a second salt. In some embodiments, the composition comprises 0.02-2.5 wt% of a first salt and / or a second salt. In some embodiments, the composition comprises 0.5-2 wt% of a first salt and / or a second salt. In some embodiments, the composition comprises 0.7-1.8 wt% of a first salt and / or a second salt. In some embodiments, the composition comprises 1-1.5 wt% of a first salt and / or a second salt.Further, the composition contains 0.01wt%-0.05wt%, 0.05wt%-0.1wt%, 0.1wt%-0.15wt%, 0.15wt%-0.2wt%, 0.2wt%-0.25wt%, 0.25wt%-0.3wt%, 0.3wt%-0.35wt%, 0.35wt%-0.4wt%, 0.4wt%-0.45wt%, 0.45wt%-0.5wt%, 0.5wt%-0.55wt%, 0.55wt%-0.6wt%, 0.6wt%-0.65wt%, and 0.65wt%-0. .7wt%, 0.7wt%-0.75wt%, 0.75wt%-0.8wt%, 0.8wt%-0.85wt%, 0.85wt%-0.9wt%, 0.9wt%-0.95wt%, 0.95wt%-1wt%, 1wt%-1.05wt%, 1 .05wt%-1.1wt%, 1.1wt%-1.15wt%, 1.15wt%-1.2wt%, 1.2wt%-1.25wt%, 1.25wt%-1.3wt%, 1.3wt%-1.35wt%, 1.35wt%-1.4wt%, 1.4wt %-1.45wt%, 1.45wt%-1.5wt%, 1.5wt%-1.6wt%, 1.6wt%-1.65wt%, 1.65wt%-1.7wt%, 1.7wt%-1.75wt%, 1.75wt%-1.8wt%, 1.8wt%-1. 85wt%, 1.85wt%-1.9wt%, 1.9wt%-1.95wt%, 1.95wt%-2wt%, 2wt%-2.05wt%, 2.05wt%-2.1wt%, 2.1wt%-2.15wt%, 2.15wt%-2.2wt%, 2. The first and / or second salt is present in amounts between 2wt% and 2.25wt%, 2.25wt% and 2.3wt%, 2.3wt% and 2.35wt%, 2.35wt% and 2.4wt%, 2.4wt% and 2.45wt%, 2.45wt% and 2.5wt%, 2.5wt% and 2.55wt%, 2.55wt% and 2.6wt%, 2.6wt% and 2.65wt%, 2.65wt% and 2.7wt%, 2.7wt% and 2.75wt%, 2.75wt% and 2.8wt%, 2.8wt% and 2.95wt%, or 2.95wt% and 3wt%.

[0066] In the composition, the catalyst and salt are mixed in a certain proportion. Further, the catalyst and salt are added in a ratio of 20:1 to 1:1. For example, the catalyst and salt are added in ratios of 20:1, 18:1, 16:1, 14:1, 12:1, 10:1, 8:1, 6:1, 4:1, 2:1, or 1:1. In some embodiments, the catalyst and salt are added in a ratio of 10:1 to 5:1. For example, the catalyst and salt are added in ratios of 10:1, 9:1, 8:1, 7:1, 6:1, or 5:1. It is understood that the salt mentioned above is a first salt and / or a second salt.

[0067] In some embodiments, the composition further includes a polymer. The polymer can act as a wetting agent and thickener, providing moisturizing and thickening effects to the composition, and can also prevent the aggregation of silica abrasive particles, reducing defects such as scratches caused by the aggregation of silica abrasive particles. The polymer can include polysaccharides, homopolymers, copolymers, or combinations thereof. Specifically, the polymer includes polysaccharides, cellulose compounds, vinyl polymers, and other similar compounds. Polysaccharides include alginate, alginates, pectin, agar, xanthan gum, chitosan, and combinations thereof. Cellulose compounds include hydroxymethyl cellulose, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC), hydroxyethyl methyl cellulose (HEMC), ethyl hydroxyethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, methyl cellulose, ethyl cellulose, propyl cellulose, cellulose acetate, and combinations thereof. Vinyl polymers include polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylamide morpholine, and combinations thereof.

[0068] The composition comprises 1-1500 ppm of a polymer. In some embodiments, the composition comprises 5-1000 ppm of a polymer. In some embodiments, the composition comprises 10-500 ppm of a polymer. In some embodiments, the composition comprises 10-200 ppm of a polymer. Further, the composition comprises a polymer between 1-100 ppm, 100-200 ppm, 200-300 ppm, 300-400 ppm, 400-500 ppm, 500-600 ppm, 600-700 ppm, 700-800 ppm, 800-900 ppm, 900-1000 ppm, 1000-1100 ppm, 1100-1200 ppm, 1200-1300 ppm, 1300-1400 ppm, or 1400-1500 ppm.

[0069] In some embodiments, the composition includes a surfactant. The surfactant can help enhance stability, increase humidity, control optical spot defects, and reduce surface roughness and haze. The surfactant can be anionic or nonionic. Anionic surfactants may include at least one of sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), or sodium salt of fatty alcohol polyoxyethylene ether sulfate (AES). Nonionic surfactants may include at least one of glucosides (e.g., alkyl polysaccharides, APG), polyethylene oxide-polypropylene oxide block copolymers (PEO-b-PPO, Pluronic), or fatty alcohol polyoxyethylene ethers (AEO).

[0070] The composition includes 0.1-100 ppm of surfactant. In some embodiments, the composition includes 0.5-50 ppm of surfactant. Further, the composition includes surfactants in the range of 1 ppm-5 ppm, 5 ppm-10 ppm, 10 ppm-15 ppm, 15 ppm-20 ppm, 20 ppm-25 ppm, or 25 ppm-30 ppm.

[0071] In some embodiments, the composition further includes a pH adjuster. The pH adjuster helps to bring the composition to a suitable pH. The pH adjuster also acts as an etchant and assists in polishing silicon-containing substrates. The pH adjuster can be a base or a salt thereof, specifically an organic base, an inorganic base, or a combination thereof. The organic base can be a quaternary ammonium hydroxide (e.g., tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH)), piperazine, pyrazine, guanidine (e.g., guanidine carbonate, guanidine hydrochloride, arginine, creatine), imidazole, triazole, methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, ethylenediamine, monoethanolamine, diethanolamine, aminoethylethanolamine, linear primary diamines (e.g., butane-1,4-diamine, pentane-1,5-diamine, hexane-1,6-diamine, heptane-1,7-diamine, octane-1,8-diamine) or a combination thereof. Inorganic bases include alkali metal hydroxides (e.g., potassium hydroxide, sodium hydroxide, lithium hydroxide), alkaline earth metal hydroxides (e.g., magnesium hydroxide, calcium hydroxide, beryllium hydroxide), alkali metal carbonates (e.g., potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, lithium bicarbonate), alkaline earth metal carbonates (e.g., magnesium carbonate, calcium carbonate, beryllium carbonate), alkali metal phosphates (e.g., tripotassium phosphate, trisodium phosphate, dipotassium phosphate, disodium phosphate), alkaline earth metal phosphates (e.g., magnesium phosphate, calcium phosphate, beryllium phosphate), ammonium carbonate, ammonium bicarbonate, ammonium hydroxide, ammonia, or combinations thereof. Preferably, the pH adjuster is an inorganic base. In some embodiments, the pH adjuster is selected from alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, ammonium carbonate, ammonia, and combinations thereof. Adding a pH adjuster can increase the material removal rate of the silicon carbide substrate.

[0072] In some embodiments, the composition further includes a buffer. The buffer may be a phosphate, a carbonate, or a combination thereof. The phosphate may include at least one of potassium dihydrogen phosphate (KH₂PO₄), dipotassium hydrogen phosphate (K₂HPO₄), or tripotassium phosphate (K₃PO₄). The carbonate may include potassium carbonate (K₂CO₃), potassium bicarbonate (KHCO₃), or combinations thereof. It is understood that the above-described buffers are merely examples of numerous buffers, and other buffers are also within the scope of this specification.

[0073] The buffer allows the composition to be maintained within a specific pH range. By controlling the pH value, the buffer can influence the removal rate of the silicon carbide substrate. The specific pH range can be 4-9, meaning the composition has a pH value of 4-9. In some embodiments, the composition has a pH value of 5-7. In some embodiments, the composition has a pH value of 5.5-6.5. Further, the composition has a pH value between 4-4.5, 4.5-5, 5-5.5, 5.5-6, 6-6.5, 6.5-7, 7-7.5, 7.5-8, 8-8.5, or 8.5-9. In some embodiments, the composition has a pH value of 9-12. Further, the composition has a pH value between 9-9.5, 9.5-10, 10-10.5, 10.5-11, 11-11.5, or 11.5-12.

[0074] Another aspect of the present invention provides a polishing method for a silicon carbide substrate, the method comprising the steps of: (a) providing the above-described chemical mechanical polishing composition; (b) contacting the silicon carbide substrate with the chemical mechanical polishing composition and a polishing pad; (c) moving the polishing pad relative to the silicon carbide substrate, wherein the chemical mechanical polishing composition is located in the middle therebetween; and (d) removing at least a portion of the silicon carbide substrate. The method may optionally include other steps.

[0075] The silica abrasive grains and the aforementioned features of the silica abrasive grains described in this application can be obtained through methods well known to those skilled in the art. In specific embodiments, colloidal silica particles can be prepared by polycondensation, for example, by condensing Si(OH)4 to form spherical particles. Si(OH)4 can be obtained by hydrolysis of alkoxysilanes or acidification of aqueous silicate solutions. Colloidal silica abrasive grains can also be prepared by precipitation from an acidic solution containing sodium silicate and sulfuric acid. Colloidal silica abrasive grains can also be purchased commercially from companies such as Bayer, DuPont, Fuso Chemical Company, Nalco, and Nissan Chemical.

[0076] The aforementioned silica abrasive and chemical additives can be added to the liquid carrier in any order and in appropriate amounts to achieve the desired concentration, thereby preparing the composition. The silica abrasive and chemical additives can be mixed and stirred in the liquid carrier. The silica abrasive and chemical additives can be added before use or at any time during the CMP process (e.g., one month, one day, one hour, or one minute).

[0077] The above-described compositions can be provided as a single-part system, a two-part system, or a multi-part system. For example, as a two-part system, the first part may contain silica abrasive particles and one or more chemical additives, and the second part may contain a first salt, a second salt, a catalyst, an oxidant, a pH adjuster, a buffer, a polymer, a surfactant, etc. The first and second parts can be combined at any time before or during the CMP process (e.g., one month, one day, one hour, or one minute), for example, when using a polishing apparatus with multiple supply paths for the CMP composition.

[0078] This invention also relates to the use of the above-described compositions of the invention. The compositions of the invention are used for chemical mechanical polishing (CMP) of silicon carbide substrates. In some embodiments, the compositions can be used for surface polishing of silicon carbide wafers, for example, for primary polishing, secondary polishing, and final polishing. As known to those skilled in the art, chemical mechanical polishing refers to: within a CMP apparatus, positioning a substrate in contact with a polishing pad and a CMP composition situated therebetween, wherein the polishing pad moves relative to the substrate to remove a portion of the substrate.

[0079] The following are specific embodiments of the compositions designed based on the above content. It should be clarified that the following embodiments are merely illustrative of the compositions and polishing methods disclosed above, and the specific implementation methods and parameters used are only one or more of the numerous parameters and methods described above. Those skilled in the art can use other parameters to perform electrochemical mechanical polishing according to the methods described above without departing from the core spirit of the application.

[0080] In the following examples, a QH-5014W pad and a KIZI polishing tool were used to polish a 6-inch diameter circular silicon carbide wafer for 40 minutes at a platen speed of 50 rpm and a head speed of 35 rpm (slurry recirculation, with no additional slurry added during recirculation). The polishing pressure was 3.5 psi, and the slurry flow rate was 100 ml / min. The material removal rate of the silicon carbide wafer was measured using an electronic balance and calculated based on the weight difference before and after polishing. The removal rates in the following examples refer to the silicon surface removal rate of the silicon carbide wafer.

[0081] Example 1

[0082] Compositions E1-E6 contain a total of 18 wt% silica abrasive particles, 0.5 wt% sodium vanadate, 0.1 wt% sodium thiosulfate, 0.1 wt% potassium nitrate (KNO3), 40 ppm sodium dodecyl sulfate, 0.1 wt% K3PO4, 3 ppm alginate, and 3 wt% hydrogen peroxide.

[0083] Table 1 reflects the relationship between the selection of abrasive particles and the material removal rate of silicon carbide substrates.

[0084] Table 1

[0085]

[0086]

[0087] As shown in Table 1 above, the removal rate of compositions E3-E6 is higher than that of compositions E1 and E2. In other words, when the silica abrasive particles are a mixture of first silica abrasive particles and second silica abrasive particles, the removal rate of the mixed abrasive particles is higher than that of the single abrasive particles.

[0088] Example 2

[0089] Compositions E7-E12 contain a total of 20 wt.% silica abrasive particles, wherein the silica abrasive particles contain 13 wt.% of first silica abrasive particles with a Z-average particle size of 45 nm. The silica abrasive particles contain 7 wt.% of second silica abrasive particles with a Z-average particle size of 120 nm. Furthermore, compositions E7-E12 also contain 0.1 wt.% potassium nitrite (KNO2), 0.1% K2SO3, 4 ppm ammonium dodecyl sulfate, 0.1% K3PO4, 100 ppm xanthan gum, and 2 wt.% hydrogen peroxide.

[0090] Table 2 shows the effect of different catalysts and different catalyst concentrations on the material removal rate of silicon carbide substrates.

[0091] Table 2

[0092] serial number catalyst Removal rate [nm / h] E7 0.02wt% Sodium vanadate 53 E8 0.1wt% Sodium vanadate 70 E9 0.5wt% Sodium vanadate 86 E10 1wt% Sodium Vanadate 110 E11 1wt% Potassium Vanadate 134 E12 5wt% Potassium Vanadate 80

[0093] It can be seen that adding a catalyst improves the material removal rate of the composition on the silicon carbide substrate.

[0094] Example 3

[0095] Compositions E13-E16 contain a total of 20 wt% silica abrasive particles. Of these, 15 wt% are first silica abrasive particles with a Z-average particle size of 60 nm. The silica abrasive particles also contain 5 wt% second silica abrasive particles with a Z-average particle size of 110 nm. Furthermore, compositions E13-E16 contain 6 ppm sodium dodecyl sulfate, 0.1 wt% potassium carbonate, 10 ppm chitosan, and 5 wt% hydrogen peroxide.

[0096] Table 3 shows the effect of adding the first salt to the composition on the material removal rate of the silicon carbide substrate.

[0097] Table 3

[0098] serial number catalyst First Salt Removal rate [nm / h] E13 0.5wt% Sodium vanadate - 86 E14 0.6wt% potassium vanadate <![CDATA[0.5wt%K2S2O3]]> 132 E15 1wt% Sodium Vanadate <![CDATA[0.05wt%KHSO3]]> 110 E16 1.2wt% ammonium vanadate <![CDATA[0.1wt%Na2SO3]]> 120

[0099] It can be seen that adding the first salt to the composition can increase the material removal rate of the silicon carbide substrate.

[0100] Example 4

[0101] Compositions E17-E23 contain 15 wt.% silica abrasive particles. These silica abrasive particles comprise 10 wt.% of first silica abrasive particles, with a Z-average particle size of 50 nm. The silica abrasive particles also comprise 5 wt.% of second silica abrasive particles, with a Z-average particle size of 130 nm. Furthermore, compositions E17-E23 contain 1 wt.% potassium vanadate, 10 ppm ammonium dodecyl sulfate, 0.1% CAPS, 5 ppm HEC, and 4 wt.% hydrogen peroxide.

[0102] Table 4 shows the effect of simultaneously adding the first salt and the second salt to the composition on the material removal rate of the silicon carbide substrate.

[0103] Table 4

[0104]

[0105]

[0106] It can be seen that the simultaneous addition of the first salt and the second salt to the composition can increase the material removal rate of the silicon carbide substrate.

[0107] In summary, this application provides a chemical mechanical polishing composition and a polishing method for polishing silicon carbide substrates. The chemical mechanical polishing composition includes a first salt, a second salt, a catalyst, and an oxidant. The first salt includes a sulfur salt. By adding a sulfur salt to the chemical mechanical polishing composition, the sulfur salt and oxidant interact to maintain the stability of the chemical environment within the composition, thereby preventing the agglomeration of silicon oxide abrasive particles and improving the material removal rate of the composition on the silicon carbide substrate.

[0108] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve the desired results. In some implementations, multitasking and parallel processing are also possible or may be advantageous.

[0109] In summary, after reading this detailed disclosure, those skilled in the art will understand that the foregoing detailed disclosure may be presented by way of example only and may not be restrictive. Although not explicitly stated herein, those skilled in the art will understand that this specification requires various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be made by this specification and are within the spirit and scope of the exemplary embodiments described herein.

[0110] Furthermore, certain terms in this specification have been used to describe embodiments of this specification. For example, "an embodiment," "an embodiment," and / or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this specification. Therefore, it is to be emphasized and understood that two or more references to "an embodiment" or "an embodiment" or "alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. Moreover, specific features, structures, or characteristics may be suitably combined in one or more embodiments of this specification.

[0111] Finally, it should be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments described in this specification. Other modified embodiments are also within the scope of this specification. Therefore, the embodiments disclosed in this specification are merely examples and not limitations. Those skilled in the art can implement the applications described in this specification using alternative configurations based on the embodiments in this specification. Therefore, the embodiments in this specification are not limited to the embodiments precisely described in the applications.

Claims

1. A chemical mechanical polishing composition for polishing a silicon carbide substrate, characterized by, The composition includes silica abrasive particles, a first salt, a second salt, a catalyst, and an oxidizing agent, the first salt including a sulfur salt.

2. The composition of claim 1, wherein, The silica abrasive particles include: first silica abrasive particles having a particle size span of at least 0.5; and second silica abrasive particles having a particle size span of at least 0.

4.

3. The composition of claim 1, wherein, The silica abrasive particles include: first silica abrasive particles; and second silica abrasive particles having a Z-average particle size that is at least 1.6 times the Z-average particle size of the first silica abrasive particles.

4. The composition of claim 1, wherein, The sulfur salt includes at least one of a thiosulfate salt, a sulfite salt, or a bisulfite salt.

5. The composition of claim 1, wherein, The second salt includes a nitrogen salt.

6. The composition of claim 5, wherein, The nitrogen salt includes at least one of a nitrate salt, a nitrite salt, or a nitride salt.

7. The composition of claim 1, wherein, The catalyst includes a vanadate salt.

8. The composition of claim 1, wherein, The composition has a pH of 5-7.

9. The composition of claim 1, wherein, The silica abrasive particles have a zeta potential of at least -8 mV in the composition at a pH of 5 to 7.

10. A polishing method for a silicon carbide substrate, characterized by, The method utilizes the composition of any of claims 1-9 to achieve polishing of a silicon carbide substrate.

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