Grinding composition

Abstract

A grinding composition is provided, comprising abrasive grains, permanganate, aluminum salt, and water. In the above grinding composition, the concentrations of the abrasive grains (W1 [wt%]), the permanganate (C1 [mM]), and the aluminum salt (C2 [mM]) satisfy at least one of the following conditions: [A], [B], [C]. [A] Satisfies both 500 ≤ (C1 / W1) and 0.04 ≤ (C2 / C1). [B] Satisfies both 200 ≤ (C1 / √(W1)) and 8 ≤ C2. [C] Satisfies both 500 ≤ (C1 / W1) and 8 ≤ C2.

Description

Technical Field

[0001] This invention relates to compositions for grinding.

[0002] This application claims priority based on Japanese Patent Application No. 2021-016870, filed on February 4, 2021, the entire contents of which are incorporated herein by reference. Background Technology

[0003] The surface of materials such as metals, semi-metals, non-metals, and their oxides is ground using an abrasive composition. For example, for surfaces composed of compound semiconductor materials such as silicon carbide, boron carbide, tungsten carbide, silicon nitride, titanium nitride, and gallium nitride, grinding (lapping) is performed by supplying diamond abrasive grains between the surface and a grinding plate. However, during grinding with diamond abrasive grains, defects and strain caused by scratches, dents, and residues are easily generated. Therefore, research is underway on grinding (polishing) using a grinding pad and an abrasive composition, either after grinding with diamond abrasive grains or as a substitute for such grinding. Patent documents 1 and 2 disclose this prior art.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-527612

[0007] Patent Document 2: International Publication No. 2020 / 087721 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] Generally, from the perspective of manufacturing efficiency and cost-effectiveness, a sufficiently high grinding removal rate is practically desired. For example, in grinding surfaces made of high-hardness materials such as silicon carbide, there is a strong desire to increase the grinding removal rate. To address this technical problem, grinding materials composed of strong oxidants such as permanganates have been used in the past. However, due to their high reactivity, they suffer from self-decomposition during storage, making it difficult to achieve the desired grinding removal rate.

[0010] Furthermore, Patent Document 1 discloses a fluid composition comprising at least one oxidant and a polyvalent cationic component. When used in a chemical mechanical polishing (CMP) process, this fluid composition is believed to achieve an appropriate material removal rate while simultaneously achieving a relatively defect-free material surface (paragraph 0005). One characteristic of Patent Document 1 is that the fluid composition does not require abrasive particles (abrasive agent) (paragraph 0005). Although it is described that an abrasive agent can be added (paragraph 0040), the main focus is on compositions that do not contain an abrasive agent. However, the need to increase the polishing removal rate in polishing compositions containing abrasive particles remains, for purposes such as improving the productivity of polished products (substrates, etc.).

[0011] Here, the grinding removal rate can be increased by setting grinding conditions such as increasing the load applied to the grinding surface during grinding to increase the processing pressure, or increasing the rotation speed of the grinding plate of the grinding device. On the other hand, in grinding compositions containing abrasive grains, if it is desired to increase the grinding removal rate by selecting its composition, the temperature rise of the grinding pad during grinding (polishing) using such a grinding composition tends to be large. In grinding compositions containing abrasive grains, if the temperature rise of the grinding pad can be suppressed, more stringent processing conditions can be adopted, which is beneficial for further improving the grinding removal rate. In addition, Patent Document 2 relates to a chemical mechanical polishing fluid with improved pH stability, but it does not address the technical problem of simultaneously achieving multiple practical grinding performances such as pH stability and grinding removal rate.

[0012] The present invention was made in view of this situation, and one of its objectives is to provide a grinding composition that can balance high grinding removal rate and suppress temperature rise of the grinding pad during grinding. Another related objective is to provide a grinding method for an object using the grinding composition.

[0013] Solution for solving the problem

[0014] According to this specification, a grinding composition is provided, comprising abrasive grains, permanganate, aluminum salt and water, wherein the concentrations of the abrasive grains W1 [wt%], the permanganate C1 [mM] and the aluminum salt C2 [mM] satisfy both of the following equations (1) and (2).

[0015] 500≤(C1 / W1) ···(1); and

[0016] 0.04≤(C2 / C1)···(2)

[0017] According to the grinding composition of this formulation, it is possible to suitably balance increasing the grinding removal rate and suppressing the rise of the grinding pad temperature (hereinafter also referred to as pad temperature) during grinding.

[0018] It should be noted that in the above formulas (1) and (2), "W1" refers to the numerical part when the content of abrasive particles in the grinding composition is expressed in "weight%", "C1" refers to the numerical part when the concentration of permanganate in the grinding composition is expressed in "mM", and "C2" refers to the numerical part when the concentration of aluminum salt in the grinding composition is expressed in "mM". W1, C1 and C2 are all dimensionless numbers.

[0019] In some preferred embodiments of the techniques disclosed herein (including grinding compositions, grinding methods, methods for manufacturing grinding media, etc. The same applies below), the concentration C2 [mM] of the aforementioned aluminum salt is 8 mM or more, for example, 8 mM or more and 1000 mM or less. By ensuring that the concentration of the aluminum salt in the grinding composition is 8 mM or more, a longer storage stability (shelf life) can be achieved.

[0020] In some methods, the concentration W1 of the aforementioned abrasive particles is 0.005% by weight or more and less than 0.5% by weight. Within this range of abrasive particle concentration, it is possible to achieve a balanced effect of increasing the grinding removal rate and suppressing the rise of the pad temperature.

[0021] In some embodiments, the pH of the abrasive composition is below 5.0. In abrasive compositions having this pH, the techniques disclosed herein are particularly effective in balancing increased abrasive removal rate with suppression of pad temperature rise.

[0022] The abrasive compositions disclosed herein are used, for example, for abrading materials with a Vickers hardness of 1500 Hv or higher. In abrading such high-hardness materials, the effects produced by the technology disclosed herein can preferably be achieved. In some embodiments, the aforementioned materials with a Vickers hardness of 1500 Hv or higher are non-oxides (i.e., non-oxide compounds). In abrading materials that are non-oxides, the effects of increased abrasive removal rate and suppression of pad temperature rise produced by the abrasive compositions disclosed herein can be suitably achieved.

[0023] The grinding compositions disclosed herein are used, for example, for grinding silicon carbide. In the grinding of silicon carbide, the effects produced by the techniques disclosed herein can preferably be achieved.

[0024] According to this specification, a grinding method for a grinding object is also provided. This grinding method includes a step of grinding the grinding object using any of the grinding compositions disclosed herein. According to this grinding method, even when grinding a grinding object made of a high-hardness material, it is possible to suppress pad temperature rise and increase the grinding removal rate. Therefore, the productivity of the target product (grinding material, such as a compound semiconductor substrate like a silicon carbide substrate) obtained by grinding using the above-described grinding method can be improved.

[0025] In addition, according to this specification, a grinding composition is provided, which comprises abrasive grains, permanganate, aluminum salt and water, wherein the concentrations of the abrasive grains W1 [wt%], the concentrations of the permanganate C1 [mM] and the concentrations of the aluminum salt C2 [mM] satisfy both of the following equations (3) and (4).

[0026] 200≤(C1 / √(W1))···(3)

[0027] 8≤C2···(4)

[0028] The grinding composition according to this formulation can improve the grinding removal rate while suppressing the rise in pad temperature, and can also improve storage stability (shelf life).

[0029] It should be noted that in the above formulas (3) and (4), "W1" refers to the numerical part when the content of abrasive particles in the grinding composition is expressed in "weight%", "C1" refers to the numerical part when the concentration of permanganate in the grinding composition is expressed in "mM", and "C2" refers to the numerical part when the concentration of aluminum salt in the grinding composition is expressed in "mM". W1, C1 and C2 are all dimensionless numbers.

[0030] In some preferred embodiments of the technology disclosed herein, the relationship between the concentration C1 [mM] of the permanganate and the concentration C2 [mM] of the aluminum salt satisfies the following equation (5).

[0031] 0.04≤(C2 / C1)···(5)

[0032] The grinding composition according to this formula can effectively suppress the rise in pad temperature.

[0033] It should be noted that in the above formula (5), "C1" refers to the numerical part when the concentration of permanganate in the grinding composition is expressed in "mM", and "C2" refers to the numerical part when the concentration of aluminum salt in the grinding composition is expressed in "mM". C1 and C2 are dimensionless numbers.

[0034] In some methods, the concentration W1 of the aforementioned abrasive particles is 0.005% by weight or more and less than 0.5% by weight. Within this range of abrasive particle concentration, it is possible to achieve a balanced effect of increasing the grinding removal rate and suppressing the rise of the pad temperature.

[0035] In some embodiments, the pH of the abrasive composition is below 5.0. In abrasive compositions having this pH, the techniques disclosed herein are particularly effective in balancing increased abrasive removal rate with suppression of pad temperature rise.

[0036] The abrasive compositions disclosed herein are used, for example, for abrading materials with a Vickers hardness of 1500 Hv or higher. In abrading such high-hardness materials, the effects produced by the technology disclosed herein can preferably be achieved. In some embodiments, the aforementioned materials with a Vickers hardness of 1500 Hv or higher are non-oxides (i.e., non-oxide compounds). In abrading materials that are non-oxides, the effects of increased abrasive removal rate and suppression of pad temperature rise produced by the abrasive compositions disclosed herein can be suitably achieved.

[0037] The grinding compositions disclosed herein are used, for example, for grinding silicon carbide. In the grinding of silicon carbide, the effects produced by the techniques disclosed herein can preferably be achieved.

[0038] According to this specification, a grinding method for a grinding object is also provided. This grinding method includes a step of grinding the grinding object using any of the grinding compositions disclosed herein. According to this grinding method, even when grinding a grinding object made of a high-hardness material, it is possible to suppress pad temperature rise and increase the grinding removal rate. Therefore, the productivity of the target product (grinding material, such as a compound semiconductor substrate like a silicon carbide substrate) obtained by grinding using the above-described grinding method can be improved.

[0039] In addition, according to this specification, a grinding composition is also provided, which comprises abrasive grains, permanganate, aluminum salt and water, wherein the concentrations of the abrasive grains W1 [wt%], the concentrations of the permanganate C1 [mM] and the concentrations of the aluminum salt C2 [mM] satisfy both of the following equations (6) and (7).

[0040] 500≤(C1 / W1) ···(6); and

[0041] 8≤C2···(7)

[0042] The grinding composition according to this formulation can improve the grinding removal rate while suppressing the rise in pad temperature, and can also improve storage stability (shelf life).

[0043] It should be noted that in the above formulas (6) and (7), "W1" refers to the numerical part when the content of abrasive particles in the grinding composition is expressed in "weight%", "C1" refers to the numerical part when the concentration of permanganate in the grinding composition is expressed in "mM", and "C2" refers to the numerical part when the concentration of aluminum salt in the grinding composition is expressed in "mM". W1, C1 and C2 are all dimensionless numbers. Detailed Implementation

[0044] The preferred embodiments of the present invention will be described below. It should be noted that, for matters not specifically described in this specification but necessary for the implementation of the present invention, these can be considered as conventional technical means employed by those skilled in the art based on existing technology. The present invention can be implemented based on the content disclosed in this specification and common technical knowledge in the field.

[0045] <Grinding Composition>

[0046] (Abrasive grains)

[0047] The grinding composition disclosed herein contains abrasive particles. According to the grinding composition containing abrasive particles, in addition to the main chemical grinding action based on permanganate and aluminum salts, the main mechanical grinding action of the abrasive particles can also be achieved, thereby realizing a higher grinding removal rate. Furthermore, since the pad temperature tends to rise when the grinding composition contains abrasive particles, the technique disclosed herein is more effective in suppressing the rise in pad temperature.

[0048] The material and properties of the abrasive particles are not particularly limited. For example, the abrasive particles can be any of inorganic particles, organic particles, and organic-inorganic composite particles. Examples include abrasive particles substantially composed of oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate or barium carbonate; etc. One type of abrasive particle can be used alone, or two or more types can be used in combination. Oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, zirconium oxide particles, manganese dioxide particles, and iron oxide particles are preferred because they can form a good surface. More preferred are silica particles, alumina particles, zirconium oxide particles, chromium oxide particles, and iron oxide particles, with silica particles and alumina particles being particularly preferred. In the use of silica particles or alumina particles as abrasives, the techniques disclosed herein can be appropriately applied to suppress the rise in pad temperature.

[0049] It should be noted that, in this specification, regarding the composition of the abrasive grains, "substantially formed of X" or "substantially composed of X" means that the proportion of X in the abrasive grains (the purity of X) is 90% or more by weight. Furthermore, the proportion of X in the aforementioned abrasive grains is preferably 95% or more, more preferably 97% or more, even more preferably 98% or more, and for example, 99% or more.

[0050] The average primary particle size of the abrasive grains is not particularly limited. From the perspective of easily obtaining the desired grinding removal rate while suppressing the rise in pad temperature, the average primary particle size of the abrasive grains can be set to 5 nm or more, 10 nm or more is appropriate, 20 nm or more is preferred, and 30 nm or more is also acceptable. From the perspective of improving the grinding removal rate, in some embodiments, the average primary particle size of the abrasive grains can be 50 nm or more, 80 nm or more, 150 nm or more, 250 nm or more, or 350 nm or more. In addition, from the perspective of suppressing the rise in pad temperature, the average primary particle size of the abrasive grains can be set to 5 μm or less, preferably 3 μm or less, more preferably 1 μm or less, and can be 750 nm or less, or 500 nm or less. From the perspective of surface quality after grinding, in some embodiments, the average primary particle size of the abrasive grains can be 350 nm or less, 300 nm or less, 180 nm or less, 150 nm or less, 85 nm or less, or 50 nm or less.

[0051] It should be noted that the average primary particle size in this specification refers to the specific surface area (BET value) determined by the BET method, calculated as: average primary particle size (nm) = 6000 / (true density (g / cm³)). 3 )×BET value (m 2 The particle size (BET particle size) is calculated using the formula ( / g). The specific surface area mentioned above can be measured, for example, using a surface area measuring device manufactured by Micromeritics, with the trade name "Flow Sorb II 2300".

[0052] The average secondary particle size of the abrasive grains can be, for example, 10 nm or more. From the perspective of easily increasing the grinding removal rate, it is preferably 50 nm or more, more preferably 100 nm or more, 250 nm or more, or 400 nm or more. From the perspective of sufficiently ensuring the number of grains per unit weight, it is appropriate to set the upper limit of the average secondary particle size of the abrasive grains to about 10 μm or less. In addition, from the perspective of suppressing the rise of pad temperature, the above-mentioned average secondary particle size is preferably 5 μm or less, more preferably 3 μm or less, for example, 1 μm or less. From the perspective of surface quality after grinding, in some cases, the average secondary particle size of the abrasive grains can be 600 nm or less, 300 nm or less, 170 nm or less, or 100 nm or less.

[0053] For abrasive particles with an average secondary diameter less than 500 nm, the volume average diameter (arithmetic mean diameter based on volume; Mv) can be measured, for example, using the dynamic light scattering method (UPA-UT151) manufactured by Nikkiso Corporation. For particles larger than 500 nm, the volume average diameter can be measured using a fine-pore resistance method (Multisizer 3) manufactured by BECKMAN COULTER Corporation.

[0054] When using alumina particles (alumina abrasives) as abrasives, a suitable selection can be made from various known alumina particles. Examples of such known alumina particles include α-alumina and intermediate alumina. Here, intermediate alumina is a general term for alumina particles other than α-alumina, specifically including γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, χ-alumina, etc. Additionally, alumina classified as fumed alumina based on the manufacturing method (typically fine alumina particles produced during high-temperature calcination of alumina salts) can be used. Furthermore, alumina referred to as colloidal alumina or alumina sol (e.g., alumina hydrates such as boehmite) is also included among the aforementioned known alumina particle examples. From a processability perspective, α-alumina is preferred. The alumina abrasives in the technology disclosed herein may contain only one type of such alumina particle or a combination of two or more types.

[0055] When using alumina particles as abrasives, it is generally advantageous to have a relatively high proportion of alumina particles in the overall abrasive. For example, the proportion of alumina particles in the overall abrasive is preferably 70% by weight or more, more preferably 90% by weight or more, even more preferably 95% by weight or more, and practically can be 100% by weight.

[0056] The particle size of alumina abrasive grains is not particularly limited and can be selected to achieve the desired grinding effect. From the perspective of improving the grinding removal rate, the average primary particle size of alumina abrasive grains is preferably 50 nm or more, more preferably 80 nm or more, and can be 150 nm or more, 250 nm or more, 300 nm or more, or 350 nm or more. The upper limit of the average primary particle size of alumina abrasive grains is not particularly limited. From the perspective of suppressing the rise of pad temperature, it is appropriate to set it to approximately 5 μm or less. From the perspective of the surface quality after grinding, it is preferably 3 μm or less, more preferably 1 μm or less, and can be 750 nm or less, 500 nm or less, 400 nm or less, or 350 nm or less.

[0057] When using alumina particles as abrasives, the grinding composition disclosed herein may also contain abrasives made of materials other than alumina (hereinafter also referred to as non-alumina abrasives) without impairing the effects of the present invention. Examples of such non-alumina abrasives include abrasives substantially composed of oxide particles such as silicon dioxide particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese oxide particles, zinc oxide particles, and iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; and carbonates such as calcium carbonate or barium carbonate.

[0058] In the grinding composition, the content of the non-alumina abrasive particles in the total weight of the abrasive particles is preferably 30% by weight or less, preferably 20% by weight or less, and more preferably 10% by weight or less.

[0059] In another preferred embodiment of the technology disclosed herein, the grinding composition comprises silica particles (silica abrasives) as abrasives. The silica abrasives can be suitably selected from a variety of known silica particles. Examples of such known silica particles include colloidal silica and dry silica. Colloidal silica is preferred. Good surface accuracy can be appropriately achieved using silica abrasives comprising colloidal silica.

[0060] The shape (appearance) of silica abrasive grains can be spherical or non-spherical. Examples of non-spherical silica abrasive grains include peanut-shaped (i.e., peanut shell-shaped), cocoon-shaped, konpeito-shaped, and rugby ball-shaped grains. In the technology disclosed herein, silica abrasive grains can be in the form of primary particles or secondary particles composed of multiple primary particles. Furthermore, primary and secondary silica abrasive grains can be mixed together. In a preferred embodiment, at least a portion of the silica abrasive grains are included in the grinding composition in the form of secondary particles.

[0061] As silica abrasive grains, silica abrasive grains with an average primary particle size greater than 5 nm are preferably used. From the perspective of grinding efficiency, the average primary particle size of the silica abrasive grains is preferably 15 nm or more, more preferably 20 nm or more, further preferably 25 nm or more, and particularly preferably 30 nm or more. The upper limit of the average primary particle size of the silica abrasive grains is not particularly limited, and it is appropriate to set it to approximately 120 nm or less, preferably 100 nm or less, and more preferably 85 nm or less. For example, from the perspective of balancing grinding efficiency and surface quality at a higher level, silica abrasive grains with an average primary particle size of 12 nm or more and 80 nm or less are preferred, and silica abrasive grains with an average primary particle size of 15 nm or more and 75 nm or less are even more preferred.

[0062] The average secondary particle size of silica abrasive grains is not particularly limited, but from the perspective of grinding efficiency, it is preferably 20 nm or more, more preferably 50 nm or more, and even more preferably 70 nm or more. In addition, from the perspective of obtaining a higher quality surface, it is appropriate for the average secondary particle size of silica abrasive grains to be 500 nm or less, preferably 300 nm or less, more preferably 200 nm or less, even more preferably 130 nm or less, and particularly preferably 110 nm or less (e.g., 100 nm or less).

[0063] The true specific gravity (true density) of the silica particles is preferably 1.5 or higher, more preferably 1.6 or higher, and even more preferably 1.7 or higher. Increasing the true specific gravity of the silica particles tends to increase their physical grinding ability. The upper limit of the true specific gravity of the silica particles is not particularly limited, but is typically 2.3 or lower, for example, 2.2 or lower, 2.0 or lower, or 1.9 or lower. The true specific gravity of the silica particles can be measured using a liquid displacement method with ethanol as the displacement fluid.

[0064] The shape (appearance) of the silica particles is preferably spherical. While not particularly limited, the average aspect ratio (average aspect ratio) of the particles is theoretically 1.00 or higher, and from the perspective of improving the grinding removal rate, it can be, for example, 1.05 or higher, or 1.10 or higher. Furthermore, an average aspect ratio of 3.0 or lower is suitable, and can also be 2.0 or lower. From the perspective of improving the smoothness of the polished surface and reducing scratches, the average aspect ratio of the particles is preferably 1.50 or lower, and can be 1.30 or lower, or 1.20 or lower.

[0065] The shape (outer diameter) and average aspect ratio of particles can be determined, for example, by observation using an electron microscope. As a specific step in determining the average aspect ratio, for example, the shapes of a predetermined number (e.g., 200) of particles are extracted using a scanning electron microscope (SEM). The smallest rectangle circumscribed to the shape of each extracted particle is drawn. Then, for each rectangle drawn for a particle shape, the length of its longer side (the value of the major diameter) is divided by the length of its shorter side (the value of the minor diameter), and the resulting value is taken as the major-to-minor diameter ratio (aspect ratio). The average aspect ratio can be obtained by taking the arithmetic mean of the aspect ratios of the predetermined number of particles.

[0066] In a polishing composition comprising silica abrasive grains, the polishing composition may also comprise abrasive grains made of materials other than silica (hereinafter also referred to as non-silica abrasive grains). Examples of particles constituting such non-silica abrasive grains include particles substantially composed of oxide particles such as alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese oxide particles, zinc oxide particles, and iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate or barium carbonate; etc. In some embodiments of a polishing composition comprising both silica and non-silica abrasive grains, the content of non-silica abrasive grains in the total weight of the abrasive grains contained in the polishing composition may, for example, be 30% by weight or less, 20% by weight or less, or 10% by weight or less.

[0067] The content of abrasive particles (e.g., silica abrasive particles, alumina abrasive particles, etc.) in the grinding composition disclosed herein is not particularly limited, as long as the concentration of the grinding composition satisfies both of the above formulas (1) and (2), both of the above formulas (3) and (4), or both of formulas (6) and (7) can be appropriately set according to the intended use and method of use of the grinding composition to achieve the desired effect. The content of abrasive particles can be, for example, less than 5% by weight, less than 3% by weight, or less than 2% by weight. From the perspective of suppressing the rise of pad temperature, the content of abrasive particles is preferably less than 1% by weight, more preferably less than 0.5% by weight, more preferably 0.4% by weight or less, less than 0.3% by weight, or less than 0.2% by weight. In some embodiments, the content of abrasive particles in the grinding composition can be less than 0.1% by weight or less than 0.1% by weight, less than 0.05% by weight or less than 0.05% by weight, less than 0.04% by weight or less than 0.04% by weight, or less than 0.03% by weight or less than 0.03% by weight. The lower limit of the abrasive content is not particularly limited, and for example, it can be 0.000001% by weight or more (i.e., 0.01 ppm or more). From the perspective of improving the performance of the abrasive, in some embodiments, the abrasive content in the grinding composition can be 0.00001% by weight or more, 0.0001% by weight or more, 0.001% by weight or more, 0.002% by weight or more, or 0.005% by weight or more. When the grinding composition disclosed herein contains a variety of abrasives, the abrasive content in the grinding composition refers to the total content of the aforementioned variety of abrasives.

[0068] The grinding composition disclosed herein preferably does not substantially contain diamond particles as particles. Diamond particles have high hardness, which can potentially be a limiting factor in improving smoothness. Furthermore, diamond particles are generally expensive, making them less cost-effective and reducing reliance on high-priced materials like diamond particles from a practical standpoint. Here, "practically not containing diamond particles" means that the proportion of diamond particles in the overall particle composition is 1% by weight or less, more preferably 0.5% by weight or less, typically 0.1% by weight or less, and in cases where the proportion of diamond particles is 0% by weight. In this manner, the application effects of the present invention can be appropriately achieved.

[0069] (permanganate)

[0070] The grinding composition disclosed herein comprises permanganate. In polishing the material to be ground (e.g., high-hardness non-oxide materials such as silicon carbide), permanganate typically functions as an oxidizing agent, thereby increasing the grinding removal rate. Alkali metal permanganates such as sodium permanganate and potassium permanganate are preferred, with potassium permanganate being the most preferred. It should be noted that permanganate may also exist in an ionic state in the grinding composition.

[0071] In some embodiments of the grinding compositions disclosed herein, the ratio of the permanganate concentration C1 [mM] to the abrasive content W1 [wt%], i.e., C1 / W1, is preferably 500 or more. That is, the relationship between C1 and W1 is linear, and as C1 / W1 becomes larger, the contribution of chemical grinding tends to increase relative to the contribution of mechanical grinding. By increasing the grinding removal rate in a composition satisfying 500 ≤ C1 / W1, a suitable balance can be achieved between a high grinding removal rate and suppression of pad temperature rise. In some embodiments, C1 / W1 can be 700 or more, 1000 or more, 1500 or more, 3000 or more, 5500 or more, or 7500 or more. The upper limit of C1 / W1 is not particularly limited. From the perspective of the storage stability of the grinding composition, it can be set to less than approximately 100,000, less than 20,000, less than 75,000, less than 50,000, less than 10,000, or less than 9,000. In some cases, C1 / W1 can be less than 7,000, less than 5,000, or less than 3,000.

[0072] In some embodiments of the grinding compositions disclosed herein, the ratio of the concentration of permanganate C1 [mM] to the square root of the content of abrasive grains W1 [wt%], i.e., C1 / √(W1), is preferably 200 or more. That is, the relationship between C1 and W1 is non-linear; as C1 / √(W1) becomes larger, the contribution of chemical grinding tends to increase relative to the contribution of mechanical grinding. By increasing the grinding removal rate in compositions satisfying 200 ≤ C1 / √(W1), a suitable balance can be achieved between high grinding removal rates and suppression of pad temperature rise. In some embodiments, C1 / √(W1) can be 300 or more, 750 or more, 1500 or more, 2500 or more, 3500 or more, or 4500 or more. The upper limit of C1 / √(W1) is not particularly limited. From the perspective of the storage stability of the grinding composition, it can be set to about 12,000 or less, 10,000 or less, 8,000 or less, or 6,000 or less. In some cases, C1 / √(W1) can be 4,500 or less, 3,500 or less, or 2,500 or less.

[0073] The concentration (content) of permanganate in any of the grinding compositions disclosed herein is not particularly limited, as long as the concentration of the grinding composition satisfies both of the above formulas (1) and (2), both of the above formulas (3) and (4), or both of formulas (6) and (7). It can be appropriately set according to the intended use and method of use of the grinding composition to achieve the desired effect. In some embodiments, from the perspective of improving the grinding removal rate, it is appropriate to set the concentration of permanganate to about 5 mM or more (i.e., 0.005 mol / L or more). From the perspective of improving the grinding removal rate, the concentration of permanganate is preferably 10 mM or more, more preferably 30 mM or more, and can be 50 mM, 70 mM or more, or 90 mM or more. From the perspective of easily achieving a higher grinding removal rate, in some embodiments, the concentration of permanganate can be 120 mM or more, 140 mM or more, or 160 mM or more. Furthermore, in some embodiments, it is appropriate to set the concentration of permanganate in the grinding composition to be about 1000 mM or less, preferably 750 mM or less, more preferably 500 mM or less, and it can be 400 mM or less, or even 300 mM or less. From the perspective of suppressing the rise in pad temperature, reducing the concentration of permanganate may be advantageous. From this perspective, in some embodiments, the concentration of permanganate can be 250 mM or less, 200 mM or less, 150 mM or less, or even 120 mM or less.

[0074] (Aluminum salts)

[0075] The grinding composition disclosed herein contains aluminum salts. In compositions containing aluminum salts in addition to abrasive grains and permanganate, grinding compositions satisfying the relationships in formulas (1) and (2) above can effectively balance increasing the grinding removal rate and suppressing the rise in pad temperature. Furthermore, in compositions containing aluminum salts in addition to abrasive grains and permanganate, grinding compositions satisfying the relationships in formulas (3) and (4) above or (6) and (7) above can increase the grinding removal rate while suppressing the rise in pad temperature, and can also improve storage stability (shelf life).

[0076] The type of salt in aluminum salts is not particularly limited; they can be inorganic acid salts or organic acid salts. Examples of inorganic acid salts include salts of hydrohalogenated hydrochloric acid, hydrobromic acid, hydrofluoric acid, nitric acid, sulfuric acid, carbonic acid, silicic acid, boric acid, and phosphoric acid. Examples of organic acid salts include salts of carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, glycine, butyric acid, citric acid, tartaric acid, and trifluoroacetic acid; organic sulfonic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid; organic phosphonic acids such as methylphosphonic acid, benzenephosphonic acid, and toluenephosphonic acid; and organic phosphoric acids such as ethylphosphonic acid. Among these, salts of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid are preferred, and salts of hydrochloric acid, nitric acid, and sulfuric acid are more preferred.

[0077] In some embodiments of the grinding compositions disclosed herein, the ratio (C2 / C1) of the concentration of aluminum salts (total concentration when multiple aluminum salts are included) C2 [mM] to the concentration of permanganate (total concentration when multiple permanganate salts are included) C1 [mM] is 0.04 or more. In compositions that satisfy the above formula (1) and have C2 / C1 of 0.04 or more, it is preferable to achieve both improved grinding removal rate and suppression of pad temperature rise. While it is not desirable to be bound by theory, it can be considered, for example, that the above-mentioned effects can be obtained by satisfying the relationship of formulas (1) and (2) as follows. That is, the permanganate contained in the grinding composition can help improve the grinding removal rate by oxidizing the surface of the grinding target material (especially high-hardness non-oxide materials such as silicon carbide). However, the above-mentioned oxidation may become a factor leading to an increase in the pH of the grinding composition supplied to the grinding target material. Therefore, if the pH of the grinding composition supplied to the grinding target material rises from the initial pH (i.e., the pH at which the grinding target material is supplied) and deviates from the appropriate pH range during grinding of the grinding target material, the chemical abrasive performance of the grinding composition on the grinding target material will decrease. It can be considered that when the chemical abrasive performance of the grinding composition decreases, the grinding removal rate decreases, and the contribution of mechanical abrasive performance relatively increases, thereby making it easier for the pad temperature to rise. However, the above investigation does not limit the scope of the present invention.

[0078] From the perspective of balancing improved grinding removal speed and suppression of pad temperature rise at a higher level, in some embodiments, C2 / C1 is preferably 0.05 or higher, more preferably 0.06 or higher, and can be 0.07 or higher, 0.08 or higher, or 0.10 or higher. The upper limit of C2 / C1 is not particularly limited, but approximately 200 or less is suitable, and it can be 100 or less, 75 or less, or 50 or less. In some preferred embodiments, C2 / C1 can be 20 or less, 10 or less, 5 or less, 1 or less, 0.6 or less, 0.5 or less, 0.3 or less, or 0.2 or less.

[0079] The concentration (content) of aluminum salt in the grinding composition is not particularly limited, as long as it satisfies the concentration of the grinding composition that satisfies both of the above formulas (1) and (2), both of the above formulas (3) and (4), or both of formulas (6) and (7). It can be appropriately set according to the purpose and method of use of the grinding composition to achieve the desired effect. The concentration of aluminum salt can be, for example, about 1000 mM or less, 500 mM or less, or 300 mM or less. In some cases, it is appropriate to set the concentration of aluminum salt to 200 mM or less, preferably 100 mM or less, more preferably 50 mM or less, 30 mM or less, 20 mM or less, or 10 mM or less. The lower limit of the concentration of aluminum salt can be, for example, 0.1 mM or more. From the perspective of properly exerting the effect of aluminum salt, it is advantageous to set it to 1 mM or more. From the perspective of storage stability, it is preferred to set it to 5 mM or more, more preferably 7 mM or more (e.g., 8 mM or more). The techniques disclosed herein can also preferably be implemented with the concentration of aluminum salt in the grinding composition being 10 mM or more, 20 mM or more, or 30 mM or more.

[0080] The relationship between the concentration of aluminum salt and the content of abrasive particles is not particularly limited as long as it satisfies the concentration of the grinding composition that satisfies both of the above formulas (1) and (2), both of the above formulas (3) and (4), or both of formulas (6) and (7). It can be appropriately set according to the purpose and method of use to achieve the desired effect. The ratio of the concentration of aluminum salt C2 [mM] to the content of abrasive particles W1 [weight %], i.e., C2 / W1, can be set to 5 or more, preferably 10 or more, more preferably 30 or more, 50 or more, or 80 or more. In some cases, C2 / W1 can be 150 or more, 300 or more, 500 or more, or 800 or more. The upper limit of C2 / W1 is not particularly limited. From the perspective of the storage stability of the grinding composition, it can be set to about 10,000 or less, 5,000 or less, or 2,500 or less. In some cases, C2 / W1 can be 1,000 or less, 800 or less, or 600 or less.

[0081] It should be noted that in the above "C2 / W1", "C2" refers to the numerical part when the concentration of aluminum salt in the grinding composition is expressed in "mM", and "W1" refers to the numerical part when the content of abrasive particles in the grinding composition is expressed in "weight%". Both C2 and W1 are dimensionless numbers.

[0082] (Alkaline earth metal salts)

[0083] The grinding composition disclosed herein may comprise at least one metal salt A selected from alkaline earth metal salts. EMS As any component. As metal salt A EMS One type of alkaline earth metal salt can be used alone, or two or more alkaline earth metal salts can be used in combination. This can be achieved by combining aluminum salts and metal salt A. EMS This can better suppress the rise in pad temperature. Metal salt A EMS As an element belonging to the alkaline earth metals, it preferably contains one or more of Mg, Ca, Sr, and Ba. Among them, it is more preferably to contain either Ca or Sr, and more preferably to contain Ca.

[0084] Metal salt A EMSThe type of salt is not particularly limited and can be either an inorganic acid salt or an organic acid salt. Examples of inorganic acid salts include salts of hydrohalogenated hydrochloric acid, hydrobromic acid, hydrofluoric acid, nitric acid, sulfuric acid, carbonic acid, silicic acid, boric acid, and phosphoric acid. Examples of organic acid salts include salts of carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, glycine, butyric acid, citric acid, tartaric acid, and trifluoroacetic acid; organic sulfonic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid; organic phosphonic acids such as methylphosphonic acid, benzenephosphonic acid, and toluenephosphonic acid; and organic phosphoric acids such as ethylphosphonic acid. Salts of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid are preferred, and salts of hydrochloric acid and nitric acid are more preferred. The technology disclosed herein, for example, preferably uses an alkaline earth metal nitrate or chloride as the metal salt A. EMS Implemented in this manner.

[0085] As a metal salt A EMS Specific examples of alkaline earth metal salts in the options include chlorides such as magnesium chloride, calcium chloride, strontium chloride, and barium chloride; bromides such as magnesium bromide; fluorides such as magnesium fluoride, calcium fluoride, strontium fluoride, and barium fluoride; nitrates such as magnesium nitrate, calcium nitrate, strontium nitrate, and barium nitrate; sulfates such as magnesium sulfate, calcium sulfate, strontium sulfate, and barium sulfate; carbonates such as magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate; and carboxylates such as calcium acetate, strontium acetate, calcium benzoate, and calcium citrate.

[0086] Metal salt A EMS Preferably, it is a water-soluble salt. This is achieved by using a water-soluble metal salt A. EMS It can efficiently form a good surface with few defects such as scratches.

[0087] In addition, the metal salt A contained in the grinding composition EMS Preferably, the compound is not oxidized by the permanganate contained in the composition. From this perspective, by appropriately selecting the permanganate and metal salt A... EMS It can prevent metal salt A EMS The deactivation of the permanganate due to oxidation inhibits the performance degradation of the grinding composition over time (e.g., a decrease in grinding removal rate). As permanganate and metal salt A... EMS One example of a preferred combination is the combination of potassium permanganate and calcium nitrate.

[0088] In the presence of metal salt A EMS In some methods, aluminum salts and metal salts A EMS The types of anions can be the same. Aluminum salts and metallic salts A EMS Common anions can include, for example, nitric acid, hydrochloric acid, sulfuric acid, and phosphoric acid. Additionally, in the presence of metal salt A... EMS In some methods, aluminum salts and metal salts A EMSThe types of anions can also be different.

[0089] In the presence of metal salt A EMS In the grinding composition, metal salt A EMS The concentration (content) is not particularly limited and can be appropriately set according to the intended use and method of application of the grinding composition to achieve the desired effect. Metal Salt A EMS The concentration can be, for example, below approximately 1000 mM, below 500 mM, or below 300 mM. From the perspective of easily and effectively balancing increased grinding removal speed and suppressed pad temperature rise when used in combination with aluminum salts, in some methods, metal salt A... EMS Setting the concentration to below 200 mM is appropriate, preferably below 100 mM, more preferably below 50 mM, and can be below 30 mM, below 20 mM, or below 10 mM. Metal salt A EMS The lower limit of the concentration can be, for example, above 0.1 mM, to appropriately utilize metal salt A. EMS From the perspective of effectiveness, it is preferable to set the concentration to 0.5 mM or more, more preferably 1 mM or more, and it can be 2.5 mM or more, or 5 mM or more. The technology disclosed herein, for example, preferably uses metal salt A in the grinding composition. EMS It is administered at a concentration of 0.5 mM to 100 mM or 1 mM to 50 mM.

[0090] Although not specifically limited, the appropriate use of metal salt A is easily achieved. EMS From the perspective of the resulting effect, the metal salt A in the grinding composition EMS Concentration (containing multiple metal salts A) EMS The ratio (C3 / C1) of the concentration of C3 [mM] (the total concentration of these oxidants) to the concentration of permanganate (the total concentration of these oxidants when multiple oxidants are included) C1 [mM] is preferably 0.001 or more, more preferably 0.005 or more, and can be 0.01 or more, or 0.02 or more. In some embodiments, C3 / C1 can be, for example, 0.03 or more, 0.05 or more, or 0.07 or more. The upper limit of C3 / C1 is not particularly limited, and it is appropriate to be approximately 100 or less, or less than 50, less than 10, or less than 5. In some preferred embodiments, C3 / C1 can be less than 1, less than 0.5, less than 0.3, or less than 0.1. In this metal salt A EMS At a concentration ratio (C3 / C1) relative to permanganate, it is preferable to further incorporate metal salt A. EMS The resulting effect.

[0091] Metal salt A EMSThe relationship between the concentration C3 [mM] and the concentration C2 [mM] of the aluminum salt is not particularly limited and can be set to appropriately maximize the effect of using them in combination. For example, C3 / C2 can be in the range of 0.001 to 1000. From the perspective of easily and appropriately balancing increasing the grinding removal rate and suppressing the rise of the pad temperature, in some cases, a C3 / C2 ratio of about 0.01 or more is suitable, and preferably 0.05 or more (e.g., 0.1 or more). In addition, a C3 / C2 ratio of about 100 or less is suitable, preferably 50 or less, and more preferably 25 or less (e.g., 10 or less).

[0092] Metal salt A EMS The relationship between the concentration and the content of abrasive particles is not particularly limited; it can be appropriately set according to the intended use and application method to achieve the desired effect. Metal Salt A EMS The ratio of the concentration C3 [mM] to the content of abrasive particles W1 [wt%], i.e., C3 / W1, can be set to 5 or more, preferably 10 or more, more preferably 30 or more, and can be 50 or more, or even 80 or more. When C3 / W1 becomes larger, the contribution of chemical polishing tends to increase relative to the contribution of mechanical polishing. In this composition, the combined use of aluminum salt and metal salt A can be appropriately utilized. EMS This helps to suppress the temperature rise of the pad. In some methods, the C3 / W1 ratio can be 100 or higher, 150 or higher, 200 or higher, 300 or higher, or 500 or higher. The upper limit of C3 / W1 is not particularly limited; from the perspective of the storage stability of the grinding composition, it can be set to approximately 5000 or lower, 2500 or lower, or 1000 or lower. In some methods, the C3 / W1 ratio can be 900 or lower, 700 or lower, or 500 or lower.

[0093] It should be noted that "C3" in the above "C3 / W1" refers to metal salt A in the grinding composition, expressed in "mM". EMS The numerical value of C3 is the concentration. Therefore, C3 is a dimensionless number.

[0094] (water)

[0095] The grinding composition disclosed herein contains water. Preferably, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc., can be used. The grinding composition disclosed herein may also contain an organic solvent (lower alcohols, lower ketones, etc.) that can be uniformly mixed with water, as needed. Generally, it is suitable for the solvent contained in the grinding composition to be at least 90% by volume water, preferably at least 95% by volume water, and more preferably at 99-100% by volume water.

[0096] (acid)

[0097] For purposes such as adjusting pH and improving grinding removal speed, the grinding composition may contain an acid as needed. The acid can be either an inorganic acid or an organic acid. Examples of inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, and carbonic acid. Examples of organic acids include aliphatic carboxylic acids such as formic acid, acetic acid, and propionic acid; aromatic carboxylic acids such as benzoic acid and phthalic acid; citric acid; oxalic acid; tartaric acid; malic acid; maleic acid; fumaric acid; succinic acid; organic sulfonic acids; and organic phosphonic acids. One of these can be used alone, or two or more can be used in combination. The amount of acid used is not particularly limited and can be set to the amount appropriate for the intended use (e.g., pH adjustment). Alternatively, some of the grinding compositions disclosed herein may be substantially acid-free.

[0098] (Alkaline compound)

[0099] For purposes such as adjusting pH and increasing the grinding removal rate, grinding compositions may contain alkaline compounds as needed. Here, an alkaline compound is a compound that has the function of raising the pH of the grinding composition by adding it to the composition. Examples of alkaline compounds include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; carbonates and bicarbonates such as ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, and sodium carbonate; ammonia; quaternary ammonium compounds, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide; and amines, phosphates, hydrogen phosphates, and organic acid salts. One alkaline compound may be used alone, or two or more may be used in combination. The amount of an alkaline compound used is not particularly limited and can be set to the amount appropriate for the intended use (e.g., adjusting pH). Alternatively, some of the grinding compositions disclosed herein may be compositions that substantially do not contain alkaline compounds.

[0100] (Other ingredients)

[0101] Without impairing the effects of the present invention, the grinding compositions disclosed herein may, as needed, include chelating agents, thickeners, dispersants, surface protectants, wetting agents, surfactants, rust inhibitors, corrosion inhibitors, fungicides, and other known additives that can be used in grinding compositions (e.g., grinding compositions used in grinding high-hardness materials such as silicon carbide). The content of the above-mentioned additives can be appropriately set according to their purpose of addition, and the features of the present invention do not lie in this, therefore detailed description is omitted.

[0102] (pH)

[0103] A pH of approximately 1 to 12 is suitable for the grinding composition. Within this pH range, a practical grinding removal rate is easily achieved. In some cases, the pH can be below 12.0, below 11.0, below 10.0, below 9.0, less than 9.0, below 8.0, less than 8.0, below 7.0, less than 7.0, or below 6.0. This facilitates the combined use of metal salt A. EMS From the perspective of improving the grinding removal speed and suppressing the rise of pad temperature with aluminum salts, in some embodiments, the pH of the grinding composition is preferably less than 6.0, can be less than 5.0, can be less than 5.0, can be less than 4.0, or can be less than 4.0. The above-mentioned pH can be, for example, 1.0 or more, 1.5 or more, 2.0 or more, or 2.5 or more.

[0104] The method for preparing the grinding composition disclosed herein is not particularly limited. For example, the components contained in the grinding composition can be mixed using a well-known mixing device such as a blade mixer, an ultrasonic disperser, or a homogenizer. The manner in which these components are mixed is not particularly limited; for example, all components can be mixed at once, or they can be mixed in a suitably set order.

[0105] The grinding compositions disclosed herein can be single-component or multi-component, primarily two-component. For example, they can be configured as follows: Component A, containing a portion of the constituent elements (e.g., elements other than water) of the grinding composition, is mixed with Component B, containing the remaining elements, and then used for grinding the object being ground. These components can be stored separately before use and mixed together to prepare a liquid grinding composition. During mixing, water or similar substances for dilution can be further added.

[0106] <Object to be ground>

[0107] The polishing object of the polishing composition disclosed herein is not particularly limited. For example, the polishing composition disclosed herein can be applied to polishing a substrate having a surface made of a compound semiconductor material, i.e., a compound semiconductor substrate. The constituent material of the compound semiconductor substrate is not particularly limited, and can be, for example, group II-VI compound semiconductors such as cadmium telluride, zinc selenide, cadmium sulfide, mercury cadmium telluride, and zinc cadmium telluride; group III-V compound semiconductors such as gallium nitride, gallium arsenide, gallium phosphide, indium phosphide, aluminum gallium arsenide, gallium indium arsenide, indium gallium arsenide, and aluminum gallium indium phosphide; group IV-IV compound semiconductors such as silicon carbide and germanium silicide; etc. These materials can be conductive materials doped with impurities, or insulating or semi-insulating materials without impurities. The polishing object can also be composed of multiple of these materials. In a preferred embodiment, the polishing composition disclosed herein can be applied to polishing a substrate having a surface made of a non-oxide (i.e., non-oxide) compound semiconductor material. In the polishing of a substrate having a surface made of a non-oxide compound semiconductor material, the polishing-promoting effect of the oxidant (typically permanganate) contained in the polishing composition disclosed herein can be readily and appropriately utilized.

[0108] The abrasive composition disclosed herein is preferably used for abrasive applications on surfaces of workpieces having a Vickers hardness of 500 Hv or higher. The Vickers hardness is preferably 700 Hv or higher, for example, 1000 Hv or higher, or 1500 Hv or higher. The Vickers hardness of the workpiece material can be 1800 Hv or higher, 2000 Hv or higher, or 2200 Hv or higher. The upper limit of the Vickers hardness of the workpiece surface is not particularly limited; for example, it can be about 7000 Hv or lower, 5000 Hv or lower, or 3000 Hv or lower. It should be noted that in this specification, Vickers hardness can be measured based on JIS R 1610:2003. The international standard corresponding to the above JIS standard is ISO 14705:2000.

[0109] Examples of materials with a Vickers hardness of 1500 Hv or higher include silicon carbide, silicon nitride, titanium nitride, and gallium nitride. The workpiece to be polished in the technology disclosed herein can have a single-crystal surface of the aforementioned materials with stable mechanical and chemical properties. Preferably, the surface of the workpiece is composed of either silicon carbide or gallium nitride, and more preferably silicon carbide. Silicon carbide is anticipated as a compound semiconductor substrate material with low power loss and excellent heat resistance, and its practical advantage of improving productivity by increasing the polishing removal speed is particularly significant. The technology disclosed herein is particularly preferred for polishing single-crystal surfaces of silicon carbide.

[0110] <Grinding Method>

[0111] The grinding methods disclosed herein may include, for example, the following operations for grinding objects.

[0112] That is, a grinding slurry (slurry) comprising any of the grinding compositions disclosed herein is prepared. Preparing the grinding slurry may include operations such as adjusting the concentration (e.g., dilution) and pH of the grinding composition. Alternatively, the grinding composition may be used directly as the grinding slurry. Furthermore, in the case of a multi-component grinding composition, preparing the grinding slurry may include operations such as mixing the components, diluting one or more components before mixing, and diluting the mixture after mixing.

[0113] Then, the polishing slurry is supplied to the object to be polished, and polishing is performed using common methods well known to those skilled in the art. For example, the object to be polished is mounted on a common polishing apparatus, and the polishing slurry is supplied to the surface of the object to be polished via the polishing pad of the apparatus. Typically, the polishing slurry is continuously supplied while the polishing pad is pressed against the surface of the object to be polished and the two are moved relative to each other (e.g., rotated). This polishing process completes the polishing of the object to be polished.

[0114] It should be noted that, for the components that may be contained in the grinding composition disclosed herein, the above-mentioned content and content ratio typically refer to the content and content ratio in the grinding composition when actually supplied to the object being ground (i.e., at point of use), and can therefore be replaced with the content and content ratio in the grinding fluid.

[0115] According to this specification, a grinding method for grinding an object to be ground (typically a grinding material) and a method for manufacturing an abrasive using this grinding method are provided. The grinding method is characterized by including a step of grinding the object to be ground using the grinding composition disclosed herein. A preferred grinding method includes a pre-polishing step and a finishing polishing step. In a typical embodiment, the pre-polishing step is a polishing step that occurs immediately before the finishing polishing step. The pre-polishing step can be a single-stage polishing step or a multi-stage polishing step with two or more stages. Furthermore, the finishing polishing step here is a step of finishing polishing the pre-polished object to be ground, and is the last (i.e., the most downstream) grinding step in a polishing process using a polishing slurry containing abrasive grains. In a grinding method including such a pre-polishing step and a finishing polishing step, the grinding composition disclosed herein can be used in the pre-polishing step, in the finishing polishing step, or in both the pre-polishing step and the finishing polishing step.

[0116] Pre-polishing and finishing polishing can be applied to either single-sided or double-sided polishing. In a single-sided polishing apparatus, the object to be polished is attached to a ceramic plate with wax, held by a holder called a support, and a polishing pad is pressed against one side of the object while a polishing composition is supplied, causing the two surfaces to move relative to each other, thereby polishing one side of the object. This movement can be, for example, rotational movement. In a double-sided polishing apparatus, the object to be polished is held by a holder called a support, and a polishing composition is supplied from above while a polishing pad is pressed against the opposite sides of the object, causing them to rotate in opposite directions, thereby polishing both sides of the object simultaneously.

[0117] The polishing conditions described above are appropriately set based on the type of material being polished, the target surface properties (specifically, smoothness), and the polishing removal rate, and are therefore not limited to specific conditions. For example, regarding processing pressure, the polishing composition disclosed herein can be used in a wide pressure range, from 10 kPa to 150 kPa. From the perspective of appropriately balancing high polishing removal rates and suppressing pad temperature rise, in some embodiments, the processing pressure can be, for example, 20 kPa or more, 30 kPa or more, or 40 kPa or more; alternatively, it can be set to 100 kPa or less, 80 kPa or less, or 60 kPa or less. The polishing composition disclosed herein is also preferably used for polishing under processing conditions of 30 kPa or more, which can improve the productivity of the target product (polished material) obtained by such polishing. It should be noted that the processing pressure mentioned herein has the same meaning as the polishing pressure.

[0118] In the polishing process described above, the rotational speed of the grinding plate and the grinding head of the grinding apparatus are not particularly limited, and can be set to approximately 10 rpm to 200 rpm. The aforementioned rotational speed can be, for example, 20 rpm or more, or 30 rpm or more. From the perspective of easily obtaining a higher grinding removal speed, in some embodiments, the aforementioned rotational speed is preferably set to 55 rpm or more, more preferably 70 rpm or more, and can be set to 85 rpm or more, 100 rpm or more, or 115 rpm or more. In grinding using the grinding composition disclosed herein, by using the aluminum salt in the grinding composition containing permanganate, the rise in pad temperature can be suppressed. Therefore, it is preferable to perform the grinding at such a high rotational speed, which can improve the productivity of the target product (grind) obtained by the grinding. Furthermore, from the perspective of suppressing the rise in pad temperature and reducing the load on the grinding apparatus, in some embodiments, the aforementioned rotational speed can be set to, for example, 180 rpm or less, 160 rpm or less, or 140 rpm or less. It should be noted that the rotational speed of the grinding plate and the rotational speed of the grinding head can be the same or different.

[0119] In the above polishing process, the area of ​​each polished object is 78.54 cm². 2 The supply rate of the abrasive composition to the object being abraded (equivalent to one side of a 4-inch wafer) can be set to, for example, 200 mL / min or less, 150 mL / min or less, or 100 mL / min or less. The lower limit of the supply rate can be set to, for example, 5 mL / min or more, 10 mL / min or more, or 15 mL / min or more.

[0120] From the perspective of reducing environmental impact and saving space in the grinding equipment by decreasing waste liquid volume, it is preferable to reduce the supply rate of the grinding composition. On the other hand, when the supply rate of the grinding composition decreases, the time the grinding composition remains on the grinding object generally increases. Therefore, it can be said that there is a tendency for the pH of the grinding composition on the grinding object to easily rise. In addition, if the supply rate of the grinding composition is reduced, the heat removed by the flow of the grinding composition generally tends to decrease, which is disadvantageous from the perspective of suppressing the rise in pad temperature. In grinding using the grinding composition disclosed herein, by using aluminum salts in the grinding composition containing permanganate, the rise in pH of the grinding composition on the grinding object can be suppressed, and the rise in pad temperature can also be suppressed, so it can be suitably implemented even with a low supply rate of the grinding composition. For example, even with a grinding object area of ​​78.54 cm²... 2 The above-described grinding can preferably be carried out at a feed rate of 50 mL / min or less, 35 mL / min or less, or even more preferably 25 mL / min or less.

[0121] The polishing pads used in the various polishing processes disclosed herein are not particularly limited. For example, any of the following can be used: non-woven fabric type, suede type, or rigid polyurethane foam type. In some embodiments, non-woven fabric type polishing pads are preferred. In the use of the above-described polishing pads, it is preferable to achieve the effect based on the technology disclosed herein, namely, the effect of suppressing the rise in pad temperature. It should be noted that the polishing pads used in the technology disclosed herein are polishing pads that do not contain abrasive particles.

[0122] The workpiece polished using the methods disclosed herein is typically cleaned after polishing. A suitable cleaning solution can be used for this cleaning. The cleaning solution used is not particularly limited; any known and commonly used cleaning solution may be selected.

[0123] It should be noted that the grinding method disclosed herein may include any other steps besides the pre-polishing and finishing polishing steps described above. Examples of such steps include a mechanical grinding step or a polishing step performed before the pre-polishing step. In the mechanical grinding step, a liquid in which diamond abrasive grains are dispersed in a solvent is used to grind the workpiece. In some preferred embodiments, the dispersion does not contain an oxidizing agent. The polishing step involves pressing the surface of a grinding plate, such as a cast iron plate, onto the workpiece for grinding. Therefore, a grinding pad is not used in the polishing step. Typically, abrasive grains are supplied between the grinding plate and the workpiece in the polishing step. These abrasive grains are typically diamond abrasive grains. Furthermore, the grinding method disclosed herein may also include additional steps before the pre-polishing step and between the pre-polishing and finishing polishing steps. These additional steps may include, for example, a cleaning step or a polishing step.

[0124] <Method for manufacturing abrasive>

[0125] The technology disclosed herein may include: a method for manufacturing an abrasive that includes a polishing step based on any of the above-described polishing methods, and an abrasive manufactured using that method. The method for manufacturing the abrasive is, for example, a method for manufacturing a silicon carbide substrate. That is, according to the technology disclosed herein, a method for manufacturing an abrasive that includes a step of polishing an object having a surface made of a high-hardness material using any of the polishing methods disclosed herein, and an abrasive manufactured using that method, are provided. According to the above manufacturing method, a substrate manufactured by polishing, such as a silicon carbide substrate, can be provided efficiently.

[0126] Example

[0127] The following describes some embodiments related to the present invention, but it is not intended to limit the present invention to the contents shown in these embodiments. It should be noted that, unless otherwise specified, "%" in the following description refers to weight.

[0128] Experiment Example 1

[0129] <Preparation of Grinding Compositions>

[0130] (Example A1)

[0131] A grinding composition containing 0.3% alumina abrasive particles, potassium permanganate as a permanganate, aluminum nitrate as an aluminum salt, and deionized water is prepared by mixing alumina abrasive particles, potassium permanganate at a concentration of 189.8 mM (Mn conversion), and aluminum nitrate at a concentration of 30.1 mM (Al conversion).

[0132] (Examples A2-A5 and Comparative Examples A1-A2)

[0133] Except for changing the concentrations of alumina abrasive particles, potassium permanganate, and aluminum nitrate as shown in Table 1, the grinding compositions involved in each example were prepared in the same manner as in Example A1.

[0134] (Comparative Example A3)

[0135] Except that aluminum nitrate was not used, the grinding composition involved in Comparative Example A3 was prepared in the same manner as in Example A3.

[0136] In the grinding compositions involved in each of Experimental Example 1, α-alumina abrasive grains with an average primary particle size of 310 nm were used as alumina abrasive grains. The pH of the grinding compositions involved in each example was adjusted to 3.0 using nitric acid.

[0137] <Grinding of the object being ground>

[0138] A SiC wafer was pre-polished using a pre-polishing composition containing alumina abrasive particles. The pre-polished SiC wafer was used as the object to be polished, and the polishing composition described in each example was directly used as the polishing slurry. The object to be polished was then polished under the polishing conditions described below.

[0139] [Polishing conditions]

[0140] Grinding device: Nachi-Fujikoshi Machinery Industry Co., Ltd., Model "RDP-500" (20-inch plate diameter)

[0141] Abrasive pad: "SUBA800XY" (non-woven fabric type) manufactured by NITTAHAAS.

[0142] Processing pressure: 44.1 kPa

[0143] Plate rotation speed: 120 rpm

[0144] Grinding head speed: 120 rpm

[0145] The slurry supply rate is 20 mL / min.

[0146] Instructions for use of polishing fluid: Dispose of immediately after use (one-way).

[0147] Grinding time: 15 minutes

[0148] Grinding target: 4-inch SiC wafers (conductive type: n-type, crystalline 4H-SiC, offset angle of the main face (0001) relative to the C-axis: 4°), 1 wafer / batch

[0149] The temperature of the polishing slurry: 23℃

[0150] <Measurement and Evaluation>

[0151] (Grinding removal speed)

[0152] Based on the above polishing conditions, after polishing the SiC wafer using the polishing composition of each example, the polishing removal rate is calculated according to the following calculation formulas (1) and (2).

[0153] (1) Grinding removal amount [cm] = Difference in weight of SiC wafer before and after grinding [g] / Density of SiC [g / cm³] 3 =3.21g / cm 3 ) / Area of ​​grinding object [cm 2 =78.54cm 2 )

[0154] (2) Grinding removal rate [nm / hour] = Grinding removal amount [cm] × 10 7 Grinding time (=15 / 60 hours)

[0155] The grinding removal rates obtained in each example were converted to relative values ​​when the comparative example A3 was 100, as shown in Table 1.

[0156] (Pad temperature)

[0157] The temperature of the polishing pad during polishing under the aforementioned polishing conditions was measured. When measuring the pad temperature, a template using a suede-like backing material was used as the wafer holding portion. During polishing, the wafer was held in a state of being wetted relative to the suede material. The pad temperature was directly obtained from the value output by the pad temperature measuring device (infrared thermal radiation thermometer) provided with the aforementioned polishing apparatus. Measurements were performed between 5 minutes and 15 minutes after the start of polishing, and the average temperature during this period was taken as the pad temperature during polishing using the polishing composition described in each example.

[0158] Substituting the results into the following formula: ΔT[°C] = (pad temperature of Comparative Example A3) - (pad temperature of each example), the pad temperature rise suppression effect was evaluated based on this ΔT (i.e., the decrease in pad temperature relative to the pad temperature of Comparative Example A3) using the following three criteria, as shown in Table 1. A larger ΔT means a better pad temperature reduction effect.

[0159] A: ΔT is greater than 0.6℃

[0160] B: ΔT greater than 0.3℃ and less than 0.6℃

[0161] C: ΔT is below 0.3℃

[0162] (Storage stability)

[0163] The storage stability of the grinding compositions prepared above was evaluated by conducting an accelerated storage test at 60°C. Specifically, the grinding compositions involved in each example were filled into a transparent polyethylene resin container and sealed. The container was left to stand at 60°C, and the number of days until the pH of the grinding compositions in the container rose above 2 was recorded as the storage stability. It should be noted that, based on the conversion based on Arrhenius's law, a storage stability of 19 days in the accelerated test at 60°C is equivalent to a storage stability of approximately 12 months at 25°C.

[0164] [Table 1]

[0165]

[0166] As shown in Table 1, the grinding compositions of Examples A1 to A5, which have a permanganate concentration [mM] to abrasive content W1 [wt%] ratio (C1 / W1) of 500 or more, and / or a permanganate concentration [mM] to the square root of abrasive content W1 [wt%] ratio (C1 / √(W1)) of 200 or more, and an aluminum salt concentration C2 [mM] to permanganate concentration C1 [mM] ratio (C2 / C1) of 0.04 or more, compared with the grinding composition of Comparative Example A3, which does not contain aluminum salt, exhibit the effect of increasing the grinding removal rate while suppressing the rise in pad temperature. On the other hand, in Comparative Examples A1 and A2, which contain aluminum salt but have smaller C1 / W1 and / or C1 / √(W1), the grinding removal rate decreases significantly compared with Comparative Example A3. In Comparative Example A1, which has a smaller C2 / C1, the effect of suppressing the rise in pad temperature is smaller.

[0167] In addition, regarding storage stability, compared with comparative examples A1 and A3 which do not contain aluminum salt or have a lower concentration, good results (longer storage stability) were obtained in examples A1 to A5 with higher aluminum salt concentrations.

[0168] (pH during grinding)

[0169] During the polishing process under the conditions described above, polishing slurry was collected from the outer end of the workpiece and its pH was measured. Slurry collection was performed 7 minutes after the start of polishing. The results are shown in Table 2.

[0170] [Table 2]

[0171] Table 2

[0172] C2 / C1 initial pH pH during grinding Example A1 0.159 3.0 3.6 Example A2 0.159 3.0 3.7 Example A3 0.119 3.0 3.7 Example A4 0.105 3.0 3.6 Example A5 0.053 3.0 4.0 Comparative Example A4 0.021 3.0 7.2 Comparative Example A1 0.035 3.0 7.2 Comparative Example A3 - 3.0 7.4

[0173] As shown in Table 2, in Comparative Example A3, which did not contain aluminum salt and had a C2 / C1 ratio of zero, it was confirmed that the pH during grinding increased significantly compared to the initial pH. In Examples A1 to A5, where the C2 / C1 ratio was 0.04 or higher, the increase in pH during grinding relative to the initial pH was smaller. In Comparative Example A1, which contained aluminum salt but had a C2 / C1 ratio less than 0.04, compared to Comparative Example A3, there was a tendency for the increase in pH during grinding to be slightly suppressed, but the effect was insufficient.

[0174] Furthermore, a grinding composition for Comparative Example A4 was prepared by changing the aluminum salt concentration of Example A5 to 4 mM, resulting in a C2 / C1 ratio of 0.021. Using the grinding composition involved in Comparative Example A4 (initial pH of 3.0), the pH during grinding was measured in the same manner. The results confirmed that the pH during grinding was similar to that of Comparative Example A1, and when C2 / C1 was less than 0.04, the effect of suppressing the pH rise during grinding was weak.

[0175] Experiment Example 2

[0176] <Preparation of Grinding Compositions>

[0177] (Example B1)

[0178] A grinding composition containing 0.1% silica abrasive particles, potassium permanganate, aluminum nitrate, and deionized water is prepared by mixing silica abrasive particles, potassium permanganate with a concentration of 189.8 mM (Mn conversion), and aluminum nitrate with a concentration of 30.1 mM (Al conversion).

[0179] (Examples B2-B3 and Comparative Example B1)

[0180] Except for changing the concentrations of silica abrasive particles, potassium permanganate, and aluminum nitrate as shown in Table 3, the grinding compositions involved in each example were prepared in the same manner as in Example B1.

[0181] (Comparative Example B2)

[0182] Except that aluminum nitrate was not used, the grinding composition involved in Comparative Example B2 was prepared in the same manner as in Example B1.

[0183] In the grinding compositions involved in each of Experimental Example 2, colloidal silica with an average primary particle size of 35 nm was used as the silica abrasive. The pH of the grinding compositions involved in each example was adjusted to 3.0 using nitric acid.

[0184] <Grinding of the object being ground>

[0185] A SiC wafer was pre-polished using a pre-polishing composition containing alumina abrasive particles. The pre-polished SiC wafer was then used as the polishing object, and the polishing composition described in each example was directly used as the polishing slurry. The polishing object was polished under the same polishing conditions as in Experimental Example 1.

[0186] <Measurement and Evaluation>

[0187] (Grinding removal speed)

[0188] The values ​​obtained in the same manner as in Experimental Example 1 were converted to relative values ​​when Comparative Example B2 was 100, as shown in Table 3.

[0189] (Pad temperature)

[0190] Substitute the values ​​obtained in the same way as in Experimental Example 1 into the following formula: ΔT[℃]=(pad temperature of Comparative Example B2)-(pad temperature of each example). Based on this ΔT (i.e., the decrease in pad temperature relative to the pad temperature of Comparative Example B2), the pad temperature rise suppression effect is evaluated according to the following three criteria, as shown in Table 3.

[0191] A: ΔT is greater than 0.6℃

[0192] B: ΔT greater than 0.3℃ and less than 0.6℃

[0193] C: ΔT is below 0.3℃

[0194] (Storage stability)

[0195] Storage stability was determined using the same accelerated testing method at 60°C as in Experimental Example 1. The results are shown in Table 3.

[0196] (pH during grinding)

[0197] The measurements were performed in the same manner as in Experiment 1. The results are shown in Table 4.

[0198] [Table 3]

[0199]

[0200] [Table 4]

[0201] Table 4

[0202] C2 / C1 initial pH pH during grinding Example B1 0.159 3.0 3.7 Example B2 0.105 3.0 3.8 Example B3 0.053 3.0 3.8 Comparative Example B1 0.021 3.0 7.2 Comparative Example B2 - 3.0 7.4

[0203] As shown in Table 3, the grinding compositions of Examples B1 to B3, with a C1 / W1 ratio of 500 or higher and / or a C1 / √(W1) ratio of 200 or higher and a C2 / C1 ratio of 0.04 or higher, showed a significant improvement in grinding removal speed while suppressing the rise in pad temperature, compared to the grinding composition of Comparative Example B2, which did not contain aluminum salts. On the other hand, in Comparative Example B1, which contained aluminum salts but had a smaller C2 / C1 ratio, the effect of suppressing the rise in pad temperature was less pronounced. Furthermore, Examples B1 to B3, with higher aluminum salt concentrations, exhibited longer storage stability compared to Comparative Examples B1 and B2, which did not contain aluminum salts or had lower concentrations. Moreover, as shown in Table 4, in Comparative Examples B1 and B2, where a C2 / C1 ratio was zero or less than 0.04, the pH during grinding increased significantly compared to the initial pH, while in Examples B1 to B3, where a C2 / C1 ratio was 0.04 or higher, the pH rise during grinding was effectively suppressed.

[0204] Experiment Example 3

[0205] <Preparation of Grinding Compositions>

[0206] Prepare the grinding compositions involved in Example A3 and Comparative Example A3 of Experimental Example 1, and the grinding compositions involved in Example B1 and Comparative Example B2 of Experimental Example 2.

[0207] Grinding of the object being ground

[0208] A SiC wafer was pre-polished using a pre-polishing composition containing alumina abrasive particles. The pre-polished SiC wafer was used as the object to be polished, and the polishing composition described in each example was directly used as the polishing slurry. The object to be polished was then polished under the following two polishing conditions.

[0209] [Polishing Condition 1]

[0210] Grinding device: Nachi-Fujikoshi Machinery Industry Co., Ltd., Model "RDP-500" (20-inch plate diameter)

[0211] Abrasive pad: NITTAHAAS "IC-1000" (rigid polyurethane type)

[0212] Processing pressure: 29.4 kPa

[0213] Plate rotation speed: 100 rpm

[0214] Grinding head speed: 100 rpm

[0215] The slurry supply rate is 20 mL / min.

[0216] How to use polishing fluid: Polish immediately after use.

[0217] Grinding time: 15 minutes

[0218] Grinding target: 4-inch semi-insulating SiC wafer (conductive type: undoped, crystalline 4H-SiC, offset angle of the main face (0001) relative to the C-axis: 0°), 1 wafer / batch

[0219] The temperature of the polishing slurry: 23℃

[0220] [Polishing Condition 2]

[0221] Grinding device: Nachi-Fujikoshi Machinery Industry Co., Ltd., Model "RDP-500" (20-inch plate diameter)

[0222] Abrasive pad: NITTAHAAS "IC-1000" (rigid polyurethane type)

[0223] Processing pressure: 39.2 kPa

[0224] Plate rotation speed: 120 rpm

[0225] Grinding head speed: 120 rpm

[0226] The slurry supply rate is 20 mL / min.

[0227] How to use polishing fluid: Polish immediately after use.

[0228] Grinding time: 15 minutes

[0229] Grinding target: 4-inch semi-insulating SiC wafer (conductive type: undoped, crystalline 4H-SiC, offset angle of the main face (0001) relative to the C-axis: 0°), 1 wafer / batch

[0230] The temperature of the polishing slurry: 23℃

[0231] <Measurement and Evaluation>

[0232] (Grinding removal speed)

[0233] Based on the above polishing conditions, after polishing the SiC wafer using the polishing composition of each example, the polishing removal rate is calculated according to the following calculation formulas (1) and (2).

[0234] (1) Grinding removal amount [cm] = Difference in weight of SiC wafer before and after grinding [g] / Density of SiC [g / cm³] 3 =3.21g / cm 3 ) / Area of ​​grinding object [cm 2 =78.54cm 2 )

[0235] (2) Grinding removal rate [nm / hour] = Grinding removal amount [cm] × 107 Grinding time (=15 / 60 hours)

[0236] The grinding removal rates obtained in Example A3 were converted to relative values ​​when Comparative Example A3 was 100, as shown in Table 5. Similarly, the grinding removal rates obtained in Example B1 were converted to relative values ​​when Comparative Example B2 was 100, as shown in Table 6.

[0237] [Table 5]

[0238] Table 5

[0239]

[0240] [Table 6]

[0241] Table 6

[0242]

[0243] As shown in Tables 5 and 6, the polishing compositions of Examples A3 and B1, even when polishing semi-insulating SiC wafers, showed an improved polishing removal rate compared to the polishing compositions of Comparative Examples A3 and B2, which do not contain aluminum salts, regardless of the polishing conditions.

[0244] The specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes technologies obtained by various modifications and alterations to the specific examples described above.

Claims

1. A grinding composition comprising abrasive grains, permanganate, aluminum salt, and water. The relationship between the concentration W1 of the abrasive particles, the concentration C1 of the permanganate, and the concentration C2 of the aluminum salt satisfies the following equations (3) and (4). in, The unit of W1 is weight%, and the units of C1 and C2 are mM. 200≤(C1 / √(W1))···(3); and 8≤C2···(4)。 2. The grinding composition according to claim 1, wherein, The relationship between the concentration C1 of the permanganate and the concentration C2 of the aluminum salt satisfies the following equation (5). The units for C1 and C2 are mM. 0.04≤(C2 / C1)···(5).

3. The grinding composition according to claim 1 or 2, wherein, The abrasive particles are selected from at least one group consisting of silicon dioxide, cerium oxide, chromium oxide, titanium dioxide, zirconium oxide, magnesium oxide, manganese dioxide, zinc oxide, iron oxide, silicon nitride, boron nitride, calcium carbonate, and barium carbonate.

4. The grinding composition according to claim 1 or 2, wherein, The abrasive particles are silicon dioxide.

5. The grinding composition according to claim 1 or 2, wherein, The concentration W1 of the abrasive particles is greater than 0.005% by weight and less than 0.5% by weight.

6. The grinding composition according to claim 1 or 2, wherein the pH is below 5.

0.

7. The grinding composition according to claim 1 or 2, wherein, The grinding composition is used for grinding materials with a Vickers hardness of 1500 Hv or higher.

8. The grinding composition according to claim 1 or 2, wherein, The grinding composition is used for grinding silicon carbide.

9. A grinding method comprising the step of grinding an object to be ground using a grinding composition according to any one of claims 1 to 8.

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