Polishing and cleaning method, cleaning agent, and polishing and cleaning kit

Abstract

Provided is a method capable of cleaning a substrate containing a high-hardness material after polishing. A method of polishing and cleaning a substrate containing a material having a Vickers hardness of 1500 Hv or more can be provided. The method includes a step of polishing a substrate to be polished using a polishing composition, and a step of cleaning the substrate polished as described above using a cleaning agent. Here, the polishing composition described above contains a polishing aid. In addition, the cleaning agent described above contains a surfactant.

Description

Technical Field

[0001] This invention relates to polishing and cleaning methods, cleaning agents, and grinding and cleaning kits. More specifically, it relates to a method for polishing and cleaning high-hardness materials with a Vickers hardness of 1500 Hv or higher, the cleaning agent used in the cleaning process, the grinding and cleaning kit, and the cleaning method.

[0002] This application claims priority based on Japanese Patent Application 2020-164596, filed on September 30, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0003] For substrates containing high-hardness materials such as diamond, sapphire (alumina), silicon carbide, boron carbide, tungsten carbide, silicon nitride, and titanium nitride, the surface is typically smoothed by lapping with diamond abrasive grains supplied to a polishing plate. However, the improvement in surface smoothness using diamond abrasive grains is limited due to the generation and residue of scratches. Therefore, a polishing process was investigated, either after or as an alternative to diamond abrasive lapping, using a polishing pad and supplying polishing slurry between the pad and the substrate. The polished substrate surface was then cleaned to remove polishing debris, polishing components, and other adhering substances. Patent documents 1-4, for example, disclose the cleaning of substrates after polishing.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-523950

[0007] Patent Document 2: Japanese Patent Application Publication No. 2013-10888

[0008] Patent Document 3: International Publication No. 2013 / 088928

[0009] Patent Document 4: Japanese Patent No. 5659152 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] The aforementioned substrate containing high-hardness materials is polished to achieve a high-quality surface. The cleaning process performed after polishing is also intended to remove deposits from the substrate surface and achieve a high-quality, clean surface. Regarding the cleaning of substrates containing high-hardness materials, for example, Patent Document 1 describes cleaning a silicon carbide substrate using a low-concentration caustic surfactant (9 < pH < 12) mixed in deionized water in an ultrasonic cleaning tank to remove particles from diamond abrasive grinding. However, Patent Document 1 does not disclose grinding using abrasive aids. Furthermore, as mentioned above, grinding with diamond abrasive grains has limited effectiveness in improving surface quality, and even after cleaning, a satisfactory surface quality is difficult to achieve. Patent Document 2 uses a cleaning agent to remove wax used in fixing the substrate. However, Patent Document 2 does not evaluate the use of the ground substrate, nor does it study the removal of deposits such as grinding debris and grinding components.

[0012] The present invention was made in view of the above circumstances, and its object is to provide a method capable of effectively cleaning a substrate containing a polished high-hardness material. A related object is to provide a cleaning agent and a polishing and cleaning kit for use in the above method. A further related object is to provide a method for cleaning the aforementioned substrate.

[0013] Solution for solving the problem

[0014] According to this specification, a method for polishing and cleaning a substrate containing a material with a Vickers hardness of 1500 Hv or higher is provided. The method includes the following steps: polishing the substrate using a polishing composition; and cleaning the polished substrate using a cleaning agent. Here, the polishing composition contains non-diamond abrasive particles and / or abrasive aids. The cleaning agent contains a surfactant. According to the above method, by performing a cleaning step using a cleaning agent containing a surfactant after a polishing step using a polishing composition containing non-diamond abrasive particles, a substrate containing a high-hardness material can be effectively cleaned. By using the cleaning agent, a substrate with less deposits and high surface quality can be achieved.

[0015] In some preferred embodiments, the aforementioned cleaning agent contains anionic surfactants as the surfactant. Surfactants that exhibit good cleaning properties on substrates containing polished, high-hardness materials can be suitably selected from anionic surfactants.

[0016] Compounds having oxoalkylene units can be listed as preferred surfactants for use in the techniques disclosed herein.

[0017] The concentration of the surfactant in the above-mentioned cleaning agent is preferably 1% by weight or more. By increasing the concentration of the surfactant, the effect of the surfactant can be better utilized, and a better cleaning effect can be preferably achieved.

[0018] In some methods, the cleaning agent may contain water in addition to surfactants. Using a water-containing cleaning agent (which can be a cleaning liquid) allows the surfactants to work more effectively.

[0019] In some preferred embodiments, the aforementioned substrate comprising a material having a Vickers hardness of 1500 Hv or higher is a silicon carbide substrate. The effects obtained from the technology disclosed herein are preferably achieved in substrates made of silicon carbide.

[0020] Additionally, according to this specification, a cleaning agent used in any of the methods disclosed herein can be provided. This cleaning agent contains a surfactant. The cleaning agent configured as described above can effectively clean substrates containing polished, high-hardness materials.

[0021] Additionally, according to this specification, a polishing and cleaning kit comprising a polishing composition and a cleaning agent can be provided. This polishing and cleaning kit can be used in any of the methods disclosed herein. In the aforementioned polishing and cleaning kit, the polishing composition comprises non-diamond abrasive grains and / or polishing aids. Furthermore, the aforementioned cleaning agent comprises a surfactant. By using this polishing and cleaning kit, a substrate containing a high-hardness material can be polished and cleaned, thereby obtaining a substrate with high surface quality and a clean surface after cleaning.

[0022] Furthermore, according to this specification, a method for cleaning a silicon carbide substrate after polishing with non-diamond abrasive grains is provided. This cleaning method includes a step of cleaning the silicon carbide substrate with a cleaning agent. Moreover, the aforementioned cleaning agent contains a surfactant. According to this cleaning method, a substrate with a well-cleaned surface and containing a high-hardness material can be obtained. Polishing with non-diamond abrasive grains is preferably polishing using a polishing composition containing non-diamond abrasive grains.

[0023] Furthermore, according to this specification, a method for cleaning a silicon carbide substrate after polishing using an abrasive aid is provided. This cleaning method includes a step of cleaning the silicon carbide substrate using a cleaning agent. Moreover, the aforementioned cleaning agent contains a surfactant. According to this cleaning method, a substrate having a well-cleaned surface and containing a high-hardness material can be obtained. Polishing using an abrasive aid is preferably polishing using a polishing composition containing an abrasive aid.

[0024] Furthermore, according to this specification, a cleaning agent for cleaning silicon carbide substrates after polishing with non-diamond abrasive grains is provided. This cleaning agent contains a surfactant. The cleaning agent described above can provide excellent cleaning results for substrates containing high-hardness materials after polishing. Polishing with non-diamond abrasive grains is preferably performed using a polishing composition containing non-diamond abrasive grains.

[0025] Furthermore, according to this specification, a cleaning agent for cleaning silicon carbide substrates after polishing using an abrasive aid is provided. This cleaning agent contains a surfactant. The cleaning agent described above can provide excellent cleaning results for substrates containing high-hardness materials after polishing. Polishing using an abrasive aid is preferably polishing using a polishing composition containing an abrasive aid. Attached Figure Description

[0026] Figure 1 This is an AFM image of the cleaned SiC wafer surface of Comparative Example 1.

[0027] Figure 2 This is an AFM image of the cleaned SiC wafer surface from Example 1.

[0028] Figure 3 This is an AFM image of the cleaned SiC wafer surface from Example 2.

[0029] Figure 4 This is an AFM image of the cleaned SiC wafer surface from Example 3.

[0030] Figure 5 This is an AFM image of the cleaned SiC wafer surface from Example 4. Detailed Implementation

[0031] The preferred embodiments of the present invention will now be described. It should be noted that any items other than those specifically mentioned in this specification that are necessary for the implementation of the present invention can be understood as conventional choices made by those skilled in the art based on prior art. The present invention can be implemented based on the disclosure in this specification and common technical knowledge in the field.

[0032] <Substrate>

[0033] The technology disclosed herein includes a method for cleaning a substrate containing a material with a Vickers hardness of 1500 Hv or higher (also known as a high-hardness material), and more specifically, a method for cleaning the substrate containing the high-hardness material after polishing. Therefore, the substrate containing the high-hardness material is both the substrate to be cleaned and the substrate to be polished. According to the method disclosed herein, the surface of the substrate containing the high-hardness material is effectively cleaned. The Vickers hardness of the high-hardness material is preferably 1800 Hv or higher (e.g., 2000 Hv or higher, typically 2200 Hv or higher). There is no particular upper limit to the Vickers hardness, and it can be about 7000 Hv or lower (e.g., 5000 Hv or lower, typically 3000 Hv or lower). It should be noted that in this specification, the Vickers hardness can be measured based on JIS R 1610:2003. The international standard corresponding to the above-mentioned JIS standard is ISO 14705:2000.

[0034] Materials with a Vickers hardness of 1500 Hv or higher include diamond, sapphire (alumina), silicon carbide, boron carbide, tungsten carbide, silicon nitride, and titanium nitride. The method disclosed herein is applicable to cleaning the surface of a single crystal of the aforementioned mechanically and chemically stable materials after polishing. The substrate surface to be polished is preferably made of silicon carbide. Compared to the Si (silicon) surface, the C (carbon) surface of a silicon carbide substrate tends to have difficulty removing polishing debris and abrasive components after polishing; the cleaning method disclosed herein is particularly suitable for cleaning such C-surfaces. Furthermore, silicon carbide is expected to be a semiconductor substrate material with low power loss and excellent heat resistance. It offers significant practical advantages in improving surface properties and is highly advantageous for cleaning surfaces that have achieved high surface quality through polishing, resulting in a clean surface. The method disclosed herein is particularly preferably used for single crystal surfaces of silicon carbide.

[0035] <Cleaning Agent>

[0036] (surfactant)

[0037] The cleaning agent disclosed herein is characterized by being a cleaning agent used for cleaning substrates containing polished high-hardness materials, and containing a surfactant. Cleaning with a cleaning agent containing a surfactant can achieve a good cleaning effect on substrates containing polished high-hardness materials. Specifically, it can remove particles and other adhering substances from the surface of the substrate containing the polished high-hardness material.

[0038] The surfactant used in the cleaning agent is not particularly limited, and any of anionic, cationic, nonionic, or amphoteric surfactants can be used. Surfactants that provide good cleaning properties for substrate surfaces containing high-hardness materials after polishing are preferably selected from anionic surfactants. Alternatively, from the viewpoint of low foaming and ease of pH adjustment, nonionic surfactants are preferred. Surfactants can be used alone or in combination of two or more.

[0039] Examples of anionic surfactants include alkyl sulfonates, alkylbenzene sulfonates (e.g., nonylbenzene sulfonate, decylbenzene sulfonate, dodecylbenzene sulfonate, etc.), naphthalene sulfonates, alkyl sulfates (e.g., dodecyl sulfate, octadecyl sulfate, etc.), polyoxyalkylene sulfates, α-olefin sulfonates, α-sulfonic acid fatty acid salts, α-sulfonic acid fatty acid alkyl esters, alkyl sulfosuccinates, dialkyl sulfosuccinates, and other sulfonic acid compounds; alkyl sulfate esters, alkenyl sulfate esters, polyoxyalkylene alkyl ether sulfate esters (e.g., polyoxyethylene octadecyl ether sulfate, polyoxyethylene dodecyl ether sulfate), polyoxyalkylene alkenyl ether sulfate esters, and other sulfate compounds; alkyl ether carboxylates, amide ether carboxylates, sulfosuccinates, amino acid surfactants, and other carboxylic acid compounds; alkyl phosphate esters, alkyl ether phosphate esters, and other phosphate compounds; etc. Among these, polyoxyalkylene alkyl ether sulfates are preferred. When anionic surfactants form a salt, the salt can be, for example, a metal salt (preferably a monovalent metal salt) such as a sodium salt, potassium salt, calcium salt, or magnesium salt, an ammonium salt, or an amine salt. Anionic surfactants can be used alone or in combination of two or more.

[0040] Examples of nonionic surfactants include alkylene oxide polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyoxyalkylene oxide derivatives (e.g., polyoxyalkylene adducts) such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene fatty acid esters, polyoxyethylene glycerol ether fatty acid esters, and polyoxyethylene sorbitan fatty acid esters; copolymers of various alkylene oxides (e.g., diblock copolymers, triblock copolymers, random copolymers, alternating copolymers); and so on. Nonionic surfactants can be used alone or in combination of two or more.

[0041] Examples of cationic surfactants include amine-type cationic surfactants such as alkylamide amines and alkylamines; quaternary ammonium salt-type cationic surfactants such as tetraalkyl (1-4 carbons) ammonium salts (e.g., tetramethylammonium salt), mono-long-chain alkyl (8-18 carbons) tri-short-chain alkyl (1-2 carbons) ammonium salts (e.g., dodecyltrimethylammonium salt, palmityltrimethylammonium salt, stearyltrimethylammonium salt), and di-long-chain alkyl (8-18 carbons) di-short-chain alkyl (1-2 carbons) ammonium salts; etc. When a cationic surfactant forms a salt, the salt can be, for example, a halide such as chlorine, bromine, or iodine; a hydroxide; or a sulfonate ester, sulfate ester, or nitrate ester with 1-5 carbons. Quaternary ammonium salt-type cationic surfactants are preferred (suitable are mono-long-chain alkyl tri-short-chain alkyl ammonium salts, di-long-chain alkyl di-short-chain alkyl ammonium salts, etc.). Cationic surfactants can be used alone or in combination of two or more.

[0042] As amphoteric surfactants, there are no particular limitations; examples include amine-epoxide type surfactants and amine oxide type surfactants. These can be used alone or in combination of two or more.

[0043] In some preferred embodiments, the surfactant used (preferably anionic surfactants) can be a compound having an oxoalkylene unit. Typically, it can be a compound having a polyoxoalkylene structure. The aforementioned oxoalkylene unit can consist of one oxoalkylene group or a repeating structure of two or more oxoalkylene units. Examples of oxoalkylene units include oxoethylene (EO) units and oxopropylene (PO) units. Among them, oxoethylene (EO) units are preferred. When the surfactant has multiple oxoalkylene units, the oxoalkylene units can be of the same type (i.e., one type) or can be composed of two or more oxoalkylene units. The total molar number of epoxides added to the surfactant can be 1 or more, 3 or more, 5 or more, 10 or more, 15 or more, 20 or more, or less than 50, less than 30, less than 22, less than 16, less than 12, less than 8, or less than 4 (e.g., less than 3).

[0044] Some surfactants used in these processes (e.g., anionic surfactants) have a hydrocarbon group. This hydrocarbon group can be composed of saturated hydrocarbons such as alkyl groups, or it can contain unsaturated bonds such as carbon-carbon double bonds. Furthermore, the hydrocarbon group (typically alkyl) can be either straight-chain or branched. The number of carbon atoms in the aforementioned hydrocarbon group (e.g., alkyl) can be 8 or more, 10 or more, 12 or more, or 24 or less, 20 or less, 18 or less, 16 or less, or 12 or less. Specific examples of hydrocarbon groups (typically alkyl) include octyl, decyl, dodecyl, myristyl, palmityl, stearyl, etc.

[0045] The pH of the surfactant (pH of a 100% by weight concentration of the surfactant, or pH of a surfactant available in the form of an article (which may contain an appropriate amount of water, etc.)) is not particularly limited. For example, it is suitable to set it to 5.0 or higher, preferably 6.0 or higher (e.g., exceeding 6.0), more preferably 6.5 or higher, further preferably 7.0 or higher, and particularly preferably 7.5 or higher (e.g., exceeding 8.0, and further 8.2 or higher). The pH of the surfactant is suitable to be, for example, below 11.0, preferably below 9.5, more preferably below 9.0 (e.g., below 9.0), and may be below 8.0, below 7.0, below 6.0, or below 5.0. By implementing cleaning using a surfactant in a near-neutral region, high surface quality can be easily achieved.

[0046] It should be noted that in this instruction manual, the pH of liquid surfactants and cleaning agents (typically cleaning solutions) is determined using a pH meter (e.g., a glass electrode hydrogen ion concentration indicator (model F-23) manufactured by Horiba Corporation). After three-point calibration using standard buffer solutions (phthalate pH buffer pH: 4.01 (25°C), neutral phosphate pH buffer pH: 6.86 (25°C), and carbonate pH buffer pH: 10.01 (25°C)), the glass electrode is placed in the cleaning agent of the test object, and the value is measured after more than 2 minutes until it stabilizes, thus allowing for accurate determination.

[0047] The concentration of the surfactant in the cleaning agent is suitably set within a range that allows the surfactant to exert its effects, and is not limited to a specific range. The concentration of the surfactant in the cleaning agent can be set to 0.01% by weight or more, and setting it to 0.1% by weight or more is suitable. In some embodiments, the concentration of the surfactant in the cleaning agent is 1% by weight or more, preferably 3% by weight or more, more preferably 10% by weight or more, further preferably 20% by weight or more, and can be 30% by weight or more, or 40% by weight or more (e.g., 50% by weight or more). In the above embodiments, the upper limit of the surfactant concentration in the cleaning agent can be set to less than 90% by weight, less than 70% by weight, less than 50% by weight, or less than 35% by weight. Such a cleaning agent can be in the form of a cleaning solution containing surfactant and water. In other embodiments, the concentration of the surfactant in the cleaning agent can be set to about 90% by weight or more (e.g., 90 to 100% by weight), setting it to 95% by weight or more is suitable, and can be 99% by weight or more. Such a cleaning agent can be substantially composed of surfactant.

[0048] (water)

[0049] In some methods, the cleaning agent contains water in addition to the surfactant. The effectiveness of the surfactant can be better utilized by using a cleaning agent containing water. Such a cleaning agent can be a liquid cleaning solution that is in a liquid state at room temperature. It should be noted that room temperature in this specification refers to 23°C. Ion-exchanged water, pure water, ultrapure water, distilled water, etc., are suitable as the water used in the cleaning agent. It should be noted that the cleaning agent disclosed herein may also further contain an organic solvent (lower alcohols, lower ketones, etc.) that can be uniformly mixed with water, as needed. Preferably, the solvent contained in the cleaning agent is 90% by volume or more water, more preferably 95% by volume or more (e.g., 99-100% by volume) water.

[0050] (Any additives)

[0051] The cleaning agents disclosed herein may be further contained, as needed, one or more of the following known additives that may be used in cleaning agents: chelating agents, pH adjusters (acidic or alkaline compounds, etc.), antioxidants, defoamers, preservatives, fungicides, etc.

[0052] Examples of chelating agents include aminocarboxylic acid chelating agents and organophosphonic acid chelating agents. Examples of aminocarboxylic acid chelating agents include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetic acid, hypozoxytriacetic acid, sodium hypozoxytriacetic acid, ammonium hypozoxytriacetic acid, hydroxyethylethylenediaminetriacetic acid, sodium hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, sodium diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, and sodium triethylenetetraminehexaacetic acid. Examples of organophosphonic acid chelating agents include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotris(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1,2-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, and α-methylphosphonosuccinic acid. Chelating agents can be used alone or in combination of two or more.

[0053] It should be noted that the cleaning agent disclosed herein may substantially not contain chelating agents. Here, "substantially not containing chelating agents" means that the concentration of chelating agents in the cleaning agent is less than 1% by weight. The concentration of chelating agents in the cleaning agent may be less than 0.3% by weight, less than 0.1% by weight, less than 0.01% by weight, or less than 0.005% by weight. The technology disclosed herein can preferably be implemented in a manner where the cleaning agent is free of chelating agents.

[0054] The content of any of the above-mentioned additives can be set within a suitable range that does not significantly impair the effects of the present invention. For example, it is suitable for the content of any additive in the cleaning agent to be less than 30% by weight, less than 10% by weight, less than 1% by weight, less than 0.1% by weight, or less than 0.01% by weight. The technology disclosed herein can preferably be implemented in a manner in which the cleaning agent does not contain any additives. It should be noted that any additive is defined as a component that is different from a solvent such as water.

[0055] The amount of any of the above-mentioned additives can also be determined by their relative relationship with the surfactant. In the cleaning agent, the content of any additive relative to 1 part by weight of the surfactant can be set to less than 3 parts by weight, and is preferably less than 1 part by weight. From the viewpoint of preferably maximizing the effect of containing the surfactant, the content of any additive relative to 1 part by weight of the surfactant can be, for example, less than 0.3 parts by weight, less than 0.1 parts by weight, less than 0.03 parts by weight, and less than 0.01 parts by weight. From the viewpoint of preferably maximizing the effect of the additive, the content of any additive relative to 1 part by weight of the surfactant can be set to 0.00001 parts by weight or more, is preferably set to 0.001 parts by weight or more, can be 0.1 parts by weight or more, can be 0.5 parts by weight or more, and can be 1 part by weight or more.

[0056] In some methods, the cleaning agent (which may be a cleaning liquid) is essentially composed of a surfactant and water. Such a cleaning agent may be in the form of an aqueous solution of the surfactant. In this method, the total ratio of surfactant to water in the cleaning agent is, for example, 90% by weight or more (e.g., 90-100% by weight), preferably 95% by weight or more, and more preferably 99% by weight or more. Thus, by using a cleaning agent that is essentially composed of a surfactant and water, there is a tendency to better utilize the effect of the surfactant.

[0057] (pH)

[0058] The pH of the cleaning agent disclosed herein is not particularly limited. For example, the pH of the cleaning agent can be 0.5 or higher, 1.0 or higher, 2.0 or higher, 3.0 or higher, or 4.0 or higher. In some preferred embodiments, it is suitable to set the pH of the cleaning agent to 5.0 or higher, preferably 6.0 or higher (e.g., above 6.0), 6.5 or higher, 7.0, 7.5 or higher, or 8.0 or higher. Additionally, the pH of the cleaning agent can be, for example, below 13.0, below 12.5, below 12.0, or lower than 12.0. In some embodiments, the pH of the cleaning agent is lower than, for example, 11.0, preferably lower than 9.5, more preferably lower than 9.0 (e.g., below 9.0), lower than 8.0, lower than 7.0, lower than 6.0, or lower than 5.0. By implementing cleaning using a cleaning agent in a near-neutral region, high surface quality can be easily achieved.

[0059] <Cleaning Method>

[0060] The cleaning method disclosed herein includes a step (cleaning step) of cleaning a substrate containing a polished high-hardness material using a cleaning agent. The cleaning agent described above can be used. The cleaning method is not particularly limited and can be implemented using suitable means depending on the purpose. For example, one or more cleaning processes selected from immersion-based cleaning, spray-jet cleaning, abrasive cleaning, and ultrasonic cleaning can be used. From a cleanability viewpoint, abrasive cleaning is preferred. It should be noted that abrasive cleaning refers to cleaning by wiping the substrate surface or performing a friction operation using cleaning tools such as sponges, brushes, or non-woven fabrics. For example, by applying a cleaning agent to the surface of the cleaning tool such as a sponge, brush, or non-woven fabric, and then moving the cleaning tool with the cleaning agent applied in contact with the substrate surface, particles and other adhering substances attached to the substrate surface can be removed. Furthermore, from the viewpoint of particle removal, it is preferable to perform the cleaning step before drying the polished substrate surface. It should be noted that the cleaning step disclosed herein can preferably be implemented without ultrasonic cleaning or microwave cleaning.

[0061] From the viewpoint of removing attached particles, abrasive cleaning using a sponge (e.g., polyvinyl alcohol (PVA) sponge) is preferred as a cleaning method. This type of cleaning is also called sponge cleaning. In addition, during the cleaning process (typically abrasive cleaning), water (deionized water, pure water, ultrapure water, distilled water, etc.) and organic solvents (lower alcohols, lower ketones, etc.) may be supplied to the substrate surface as needed, or they may not be supplied.

[0062] There is no particular limitation on the cleaning time using cleaning agents. From the viewpoint of particle removal from the substrate surface, a time of 10 seconds or more is suitable, preferably 30 seconds or more, and more preferably 1 minute or more. In addition, from the viewpoint of cleaning efficiency, a time of about 30 minutes or less is suitable, preferably 10 minutes or less, and more preferably 3 minutes or less (e.g., 1 to 2 minutes).

[0063] The temperature of the cleaning agent in the cleaning process can usually be at room temperature (typically above 10°C and below 40°C, for example, around 20-30°C). Alternatively, the cleaning agent can be heated (for example, heated to above 40°C or around 50-80°C) and then used for cleaning.

[0064] In some preferred methods, a pre-cleaning (also called pre-cleaning) is performed before the cleaning process using the aforementioned cleaning agent. Pre-cleaning is cleaning without using the aforementioned cleaning agent, and can be, for example, one or more methods selected from immersion-based cleaning, running water cleaning, spray-jet cleaning, abrasive cleaning, ultrasonic cleaning, etc. For example, pre-cleaning can be immersion in water (deionized water, pure water, ultrapure water, distilled water, etc. Unless otherwise stated, the same applies hereinafter.), running water cleaning, spray-jet cleaning, abrasive cleaning using water, ultrasonic cleaning in a water tank containing water, etc. Immersion in water can be intermittent immersion of the substrate in a water tank containing stored water, overflow immersion while water overflows from the tank, or rapid pouring immersion. From a cleanability point of view, abrasive cleaning is preferred. Abrasive cleaning using water is preferably performed while water is supplied (running water) to the substrate surface. As abrasive cleaning in pre-cleaning, abrasive cleaning using a sponge (e.g., PVA sponge) is preferred. From the viewpoint of removing attached particles, it is preferable to perform the pre-cleaning process before the polished substrate surface dries, and more preferably, to perform the cleaning process after the pre-cleaning process and before the substrate surface dries. It should be noted that the water may also contain an appropriate amount of organic solvent (lower alcohols, lower ketones, etc.).

[0065] There is no particular time limit for the pre-cleaning process. From a cleaning point of view, 10 seconds or more is suitable, and 30 seconds or more is preferred. In addition, from a cleaning efficiency point of view, it is suitable to set it to about 10 minutes or less, and preferably 3 minutes or less (e.g., 1 to 2 minutes).

[0066] In some methods, a post-cleaning process is performed after the cleaning step using the aforementioned cleaning agent. Besides being performed after the aforementioned cleaning step, the post-cleaning process can also be performed using the same method as the pre-cleaning process described above, therefore, repeated explanations are omitted. In the post-cleaning process, a combination of running water rinsing and immersion rinsing (e.g., overflow immersion) is preferably used. When using immersion rinsing, it is suitable to set the post-cleaning process for at least 1 minute, preferably at least 10 minutes (e.g., approximately 10 to 30 minutes).

[0067] The cleaning method disclosed herein uses surfactants, and in a preferred manner, abrasive cleaning with a sponge is used, which can achieve good cleaning results on substrates containing high-hardness materials. Therefore, in general, it can be preferably implemented by means of ultrasonic cleaning or microwave cleaning, which are not fully utilized in existing cleaning methods.

[0068] As described above, the surface roughness Ra of the cleaned substrate is not particularly limited, and can be, for example, about 3 nm or less. The surface roughness Ra is preferably about 1 nm or less, more preferably about 0.3 nm or less, and even more preferably less than 0.10 nm (e.g., about 0.01 to 0.07 nm). Furthermore, the Rmax of the cleaned substrate is not particularly limited, but is preferably less than 30 nm, more preferably less than 20 nm, and even more preferably less than 10 nm. By performing cleaning using the cleaning agent disclosed herein, a high-quality and clean surface can be achieved as described above. The Ra and Rmax were measured using atomic force microscopy (AFM) as described in the embodiments described later.

[0069] After cleaning, the substrate containing high-hardness material is forced to dry by natural drying, drying machine or other means, and can be used as a semiconductor substrate material, preferably for various device applications such as optical devices and power devices.

[0070] <Substrate Manufacturing Method>

[0071] Furthermore, according to this specification, a method for manufacturing a substrate containing a high-hardness material, including the cleaning method described above, can be provided. The method for manufacturing the substrate described above is, for example, a method for manufacturing a silicon carbide substrate. The technology disclosed herein can include a method for providing a substrate containing a high-hardness material and a substrate containing a high-hardness material manufactured using this method. That is, according to the technology disclosed herein, a method for manufacturing a substrate containing a high-hardness material and a substrate containing a high-hardness material manufactured using this method can be provided, the method for manufacturing the substrate containing the high-hardness material including: a cleaning step of supplying any cleaning agent disclosed herein to the substrate containing the high-hardness material to clean the substrate. The above manufacturing method can be implemented by preferably applying any of the cleaning methods disclosed herein. According to the above manufacturing method, a clean substrate, such as a silicon carbide substrate, with improved surface quality can be effectively produced.

[0072] Furthermore, the method for manufacturing a substrate containing a high-hardness material may include a polishing step (polishing step) of the substrate containing the high-hardness material to be polished before the aforementioned cleaning step. Specifically, the polishing step involves grinding the surface of the substrate containing the high-hardness material using the polishing composition described later. By applying the cleaning agent and cleaning method disclosed herein to the polished substrate containing the high-hardness material after the polishing step described later, the desired effect can preferably be achieved. The cleaning agent and cleaning method disclosed herein can preferably be implemented in combination with the polishing process described later. Therefore, according to this specification, a method for polishing and cleaning a substrate containing a high-hardness material can be provided. The polishing composition and polishing method will be described below.

[0073] <Polishing Composition>

[0074] (Abrasive grains)

[0075] The polishing compositions disclosed herein typically contain abrasive particles. From the viewpoint of effectively achieving excellent smoothness, it is preferable that the polishing compositions contain abrasive particles. There is no particular limitation on the types of abrasive particles that may be included in the polishing compositions. 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; carbonates such as calcium carbonate and barium carbonate; etc. Abrasive particles can be used alone or in combination of two or more. Among these, 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. In some methods, alumina particles, zirconium oxide particles, chromium oxide particles, and iron oxide particles are preferred, with alumina particles being particularly preferred. In other methods, silica particles, cerium oxide particles, and manganese dioxide particles are further preferred, with silica particles being particularly preferred.

[0076] It should be noted that, in this specification, regarding the composition of abrasive grains, "substantially contains X" or "substantially constitutes X" means that the proportion of X in the abrasive grain (the purity of X) is 90% or more by weight (preferably 95% or more, more preferably 97% or more, even more preferably 98% or more, for example 99% or more).

[0077] In some methods, alumina particles can be used as abrasives. Alumina particles can be used alone or in combination of two or more. When using alumina particles as abrasives, a higher proportion of alumina particles in the overall abrasive composition is generally advantageous. For example, the proportion of alumina particles in the overall abrasive composition is preferably 70% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more (e.g., 95-100% by weight).

[0078] In some preferred embodiments, silica particles can be used as abrasives. Examples of silica particles include colloidal silica, fumed silica, and precipitated silica. From the viewpoint of improving smoothness, colloidal silica and fumed silica are preferred silica particles. Colloidal silica is particularly preferred. The technology disclosed herein is suitable for polishing methods including polishing compositions containing silica particles. In the polishing of substrates using silica particles, when silica particles adhere to the substrate surface, their removal is generally more difficult than that of other particles. According to the technology disclosed herein, the silica particles adhering to such substrate surfaces can be suitably removed using the aforementioned cleaning agents. Silica particles can be used alone or in combination of two or more.

[0079] Using silica particles as abrasive grains A FIN In this case, it is generally advantageous to have a higher proportion of silica particles in the abrasive grains contained in the polishing composition. For example, the proportion of silica particles in the abrasive grains contained in the polishing composition is preferably 70% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more (e.g., 95 to 100% by weight).

[0080] Furthermore, the polishing composition disclosed herein preferably uses non-diamond abrasive grains that do not substantially contain diamond particles as abrasive grains. Diamond particles have high hardness, which can be a limiting factor in improving smoothness. Additionally, since diamond particles are generally expensive, they are not considered cost-effective materials, and from a practical standpoint, it is desirable to have less reliance on expensive materials such as diamond particles.

[0081] The average primary particle size of the abrasive grains (e.g., silica particles) is not particularly limited, but from the viewpoint of improving the grinding removal rate, it is 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more, and can be 50 nm or more, or 60 nm or more. By increasing the average primary particle size, a higher grinding removal rate can be achieved. Furthermore, from the viewpoint of the surface quality after grinding, the aforementioned average primary particle size is typically 500 nm or less, and setting it to 300 nm or less is suitable, preferably 150 nm or less, more preferably 100 nm or less, and even more preferably 80 nm or less, for example, 60 nm or less.

[0082] It should be noted that the average primary particle size of the abrasive grains disclosed herein refers to: based on the specific surface area (BET value) measured using the BET method, calculated as: average primary particle size (nm) = 6000 / (true density (g / cm³)). 3 )×BET value (m 2The particle size (BET particle size) is calculated using the formula / g). Specific surface area can be determined, for example, using a surface area measuring device manufactured by Micromeritics, trade name "Flow Sorb II 2300".

[0083] When a polishing composition contains abrasive grains, from the viewpoint of abrasive removal rate, it is generally suitable to set the abrasive grain concentration in the polishing composition to 0.01% by weight or more, which can be 0.1% by weight or more, 1% by weight or more, or 3% by weight or more. From the viewpoint of effectively improving smoothness, the above-mentioned abrasive grain concentration is preferably 10% by weight or more, more preferably 20% by weight or more. In addition, from the viewpoint of obtaining good dispersibility, it is generally suitable to set the abrasive grain concentration in the fine polishing composition to 50% by weight or less, preferably 40% by weight or less, which can be 20% by weight or less, 10% by weight or less, or 8% by weight or less. In some other ways, from the viewpoint of obtaining the desired surface quality, the polishing composition may not contain abrasive grains.

[0084] (Grinding aid)

[0085] The polishing composition disclosed herein preferably includes an abrasive aid. The abrasive aid is a component that enhances the polishing effect, and is typically a water-soluble substance. There is no particularly limiting interpretation of the abrasive aid, but it is considered to have an effect in polishing that degrades the substrate surface (typically oxidative degradation), leading to surface brittleness and thus facilitating abrasive polishing using abrasive grains. For example, taking silicon carbide (SiC), a representative example of a high-hardness material, as an example, it can be considered that during polishing, the abrasive aid contributes to the oxidation of SiC, i.e., SiO₂. x C y This contributes to the chemical process. The SiO₂ x C y Its hardness is lower than that of SiC single crystal. Furthermore, in high-hardness materials with a Vickers hardness exceeding 1500 Hv, oxidation generally leads to decreased hardness and brittleness. Based on this, it is believed that adding polishing aids can improve the polishing removal speed and the surface quality of the substrate.

[0086] Examples of grinding aids include: peroxides such as hydrogen peroxide; nitric acid, its salts such as ferric nitrate, silver nitrate, and aluminum nitrate, and its complexes such as cerium ammonium nitrate; persulfates such as potassium persulfate and persulfate, and its salts such as ammonium persulfate and potassium persulfate; chloric acid and its salts, perchloric acid, and its salts such as potassium perchlorate; bromineic acid and its salts such as potassium bromate; iodic acid, its salts such as ammonium iodate and periodic acid. Iodine compounds such as sodium periodate and potassium periodate; ferric acids such as potassium ferrate as its salts; permanganic acids such as sodium permanganate and potassium permanganate as its salts; chromic acids such as potassium chromate and potassium dichromate as its salts; vanadic acids such as ammonium vanadate, sodium vanadate, and potassium vanadate as its salts; ruthenic acids such as perruthenic acid or its salts; molybdic acids such as ammonium molybdate and disodium molybdate as its salts; rhenium acids such as perrhenic acid or its salts; and tungstic acids such as disodium tungstate as its salts. They can be used individually or in combination of two or more. In some methods, permanganic acid or its salts, chromic acid or its salts, and ferric acid or its salts are preferred, with sodium permanganate and potassium permanganate being particularly preferred. Among other methods, vanadic acid or its salts, iodine compounds, molybdic acid or its salts, tungstic acid or its salts are preferred, with sodium metavanadate, sodium vanadate, and potassium vanadate being particularly preferred.

[0087] In some preferred embodiments, the polishing composition includes a composite metal oxide as a polishing aid. Examples of such composite metal oxides include metal nitrate salts, ferric oxides, permanganate oxides, chromate oxides, vanadate oxides, ruthenium oxides, molybdate oxides, rhenium oxides, and tungstate oxides. More preferably, ferric oxides, permanganate oxides, chromate oxides, vanadate oxides, molybdate oxides, and tungstate oxides are preferred, and more preferably, permanganate oxides and vanadate oxides are preferred.

[0088] The polishing compositions disclosed herein may or may not contain oxidants other than the aforementioned composite metal oxides. The techniques disclosed herein are preferably implemented in a manner that includes the aforementioned composite metal oxides and oxidants other than the aforementioned composite metal oxides (e.g., hydrogen peroxide) as oxidants. Alternatively, the techniques disclosed herein may also be implemented in a manner that substantially does not contain polishing aids other than the aforementioned composite metal oxides (e.g., hydrogen peroxide) as polishing aids.

[0089] The content of the abrasive aid in the polishing composition is typically set at 0.005 mol / L or more. From the viewpoint of improving the abrasive removal rate, the content of the abrasive aid in the polishing composition is preferably 0.008 mol / L or more, more preferably 0.01 mol / L or more, and can be 0.03 mol / L or more, 0.05 mol / L or more, 0.06 mol / L or more, or 0.07 mol / L or more. From the viewpoint of improving smoothness, the content of the abrasive aid in the polishing composition is typically set at 0.5 mol / L or less, preferably 0.3 mol / L or less, more preferably 0.2 mol / L or less, and can be 0.1 mol / L or less, or 0.09 mol / L or less.

[0090] (Other ingredients)

[0091] The polishing compositions disclosed herein may, without impairing the effects of the present invention, further contain, as needed, known additives that can be used in polishing compositions (typically compositions for polishing high-hardness materials, such as compositions for polishing silicon carbide substrates), including metal salts, alkali metal salts, alkaline earth metal salts, chelating agents, thickeners, dispersants, pH adjusters, surfactants, inorganic polymers, organic polymers, organic acids, organic acid salts, inorganic acids, inorganic acid salts, rust inhibitors, preservatives, and mildew inhibitors. The content of these additives can be appropriately set according to their purpose and is not intended to characterize the present invention; therefore, detailed descriptions are omitted.

[0092] (Dispersion medium)

[0093] The dispersion medium used in the polishing composition is not particularly limited as long as it can disperse abrasive grains. Ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc., are preferred as the dispersion medium. The polishing 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 preferred that 90% by volume or more of the dispersion medium contained in the polishing composition is water, more preferably 95% by volume or more (typically 99-100% by volume) is water.

[0094] There are no particular limitations on the pH of the polishing composition. Generally, a pH of around 2 to 12 is suitable. If the pH of the polishing composition is within this range, a practical abrasion removal rate can be easily achieved. The pH of the polishing composition is preferably 2 to 10, more preferably 3 to 9.5, and can also be 4 to 8. In some embodiments, the pH of the polishing composition can be, for example, 6 to 10, or 8.5 to 9.5.

[0095] There are no particular limitations on the preparation method of the polishing composition disclosed herein. For example, it is preferable to use a well-known mixing device such as a blade mixer, an ultrasonic disperser, or a homogenizer to mix the components contained in the polishing composition. There are no particular limitations on the manner in which these components are mixed; for example, all components may be mixed at once, or they may be mixed in a suitably set order.

[0096] The polishing composition disclosed herein can be a single-component type or a multi-component type, such as a two-component type. For example, it can be configured such that liquid A, containing a portion of the components of the polishing composition, and liquid B, containing the remaining components, are separately stored, and liquid A and liquid B are mixed and used when polishing a substrate.

[0097] The polishing composition disclosed herein can be in a concentrated form (i.e., a concentrated form of polishing slurry) before use in polishing. Such a concentrated form of the polishing composition is advantageous from the viewpoints of convenience in manufacturing, distribution, and storage, as well as cost reduction.

[0098] <Grinding and Cleaning Kit>

[0099] Based on the above, and according to this specification, a grinding and cleaning kit for use in grinding and cleaning substrates containing high-hardness materials is provided. This grinding and cleaning kit comprises a polishing composition and a cleaning agent. The polishing composition is used for polishing substrates containing high-hardness materials, and the cleaning agent is used for cleaning substrates containing high-hardness materials after polishing using the polishing composition. More specifically, the grinding and cleaning kit is used in a method for manufacturing substrates containing high-hardness materials. The polishing composition disclosed herein can be used as the polishing composition. The cleaning agent disclosed herein can be used as the cleaning agent. Specifically, the polishing composition may, for example, contain a grinding aid. Additionally, it may contain, for example, abrasive grains (suitably non-diamond abrasive grains). Additionally, the cleaning agent contains a surfactant. The polishing composition and the cleaning agent are typically stored separately from each other. Substrates manufactured using the grinding and cleaning kit have high surface quality after grinding and become substrates with clean surfaces after cleaning. Details regarding the polishing composition and cleaning agent are as described above, and therefore omitted here.

[0100] <Grinding Method>

[0101] The polishing compositions disclosed herein can be used when polishing a substrate, for example, by including the following operations: A polishing slurry (paste) comprising any of the polishing compositions disclosed herein is prepared. The preparation of the polishing slurry may include adjusting the concentration of the polishing composition (e.g., diluting the polishing composition), adjusting the pH of the polishing composition, etc. Alternatively, the polishing composition may be used directly as the polishing slurry. Furthermore, in the case of multi-component polishing compositions, the preparation of the polishing slurry may include mixing the solvents; diluting one or more reagents before mixing; and diluting the mixture after mixing. Next, the polishing slurry is supplied to the polishing surface, and polishing is performed using conventional methods employed by those skilled in the art. For example, a method in which the substrate is mounted on a conventional polishing apparatus, and the polishing slurry is supplied to the polishing surface of the substrate via the polishing pad of the polishing apparatus. Typically, the polishing slurry is continuously supplied, and the polishing pad is pressed against the polishing surface of the substrate, causing relative movement (e.g., rotational movement). The polishing of the substrate is completed through the above polishing process.

[0102] According to this specification, a polishing method for polishing a substrate and a method for manufacturing a substrate using the polishing method are provided. The polishing method is characterized by including a step of polishing a substrate using the polishing composition disclosed herein. Some preferred polishing methods include a pre-polishing step (pre-polishing step) and a fine polishing step (fine polishing step). In some preferred embodiments, the pre-polishing step is a polishing step performed before the fine 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 fine polishing step referred to herein is a step of finely polishing the pre-polished substrate, meaning it is the last (i.e., the most downstream) polishing step in a polishing process using a polishing slurry containing abrasive particles. Thus, in a polishing method including a pre-polishing step and a fine polishing step, the polishing composition disclosed herein can be used in one step of the pre-polishing step, in the fine polishing step, or in both the pre-polishing step and the fine polishing step.

[0103] Pre-polishing and fine polishing can be performed using either a single-sided polishing apparatus or a double-sided polishing apparatus. In a single-sided polishing apparatus, a substrate is adhered to a ceramic plate with wax, the substrate is held by a holder called a carrier, and a polishing pad is pressed against one side of the substrate while a polishing composition is supplied, causing the two to move relative to each other, thereby polishing one side of the object to be polished. This movement is, for example, rotational movement. In a double-sided polishing apparatus, the substrate is held by a holder called a carrier, and a polishing pad is pressed against the opposite surfaces of the substrate while a polishing composition is supplied from above. Both sides of the substrate are polished simultaneously by rotating them in opposite directions.

[0104] There are no particular limitations on the abrasive pads used in the various polishing processes disclosed herein. For example, any type can be used, such as non-woven fabric, synthetic leather, rigid polyurethane foam, abrasive-containing type, or non-abrasive-containing type. In some embodiments, non-woven fabric or rigid polyurethane foam abrasive pads may be preferred.

[0105] Substrates polished using the methods disclosed herein are typically cleaned after polishing. The above-described cleaning process is a cleaning method disclosed herein (a cleaning method using a cleaning agent containing a surfactant).

[0106] It should be noted that the polishing method disclosed herein may include any other steps besides the pre-polishing and fine polishing steps described above. Examples of such steps include a mechanical polishing step performed before the pre-polishing step and a polishing step. The mechanical polishing step uses a liquid obtained by dispersing diamond abrasive grains in a solvent to polish the substrate. In some preferred embodiments, the dispersion does not contain an oxidizing agent. The polishing step involves pressing the surface of a polishing plate, such as a cast iron table, onto the substrate for polishing. Therefore, no polishing pad is used in the polishing step. The polishing step is typically performed by supplying abrasive grains between the polishing plate and the substrate. These abrasive grains are typically diamond abrasive grains. Furthermore, the polishing method disclosed herein may include steps added before the pre-polishing step or between the pre-polishing and fine polishing steps.

[0107] Example

[0108] The following describes several embodiments related to the present invention, but is not intended to limit the invention to those embodiments. It should be noted that, unless otherwise stated, "%" in the following description refers to weight.

[0109] <Comparative Example 1>

[0110] [Polishing Test]

[0111] (Preparation of the polishing composition)

[0112] A polishing slurry was prepared by mixing colloidal silica as abrasive particles, hydrogen peroxide and vanadate as polishing aids, and deionized water. The average primary particle size of the colloidal silica used was approximately 80 nm. The concentration of abrasive particles in the polishing slurry was 23%.

[0113] (Polishing conditions)

[0114] Preparation: The SiC wafers were pre-polished using diamond abrasive grains with an average particle size of 5 μm, and pre-polished using an abrasive slurry that further contained alumina abrasive grains.

[0115] The surface of a pre-polished SiC wafer was ground using the prepared polishing slurry under the following polishing conditions.

[0116] Grinding device: RDP-500 surface grinding device manufactured by Nachi-Fujikoshi Machinery Industry Co., Ltd.

[0117] Grinding pad: Nitta Haas Incorporated, manufactured "SUBA800".

[0118] Grinding pressure: 300g / cm 2

[0119] Plate rotation speed: 80 rpm

[0120] Grinding head speed: 40 rpm

[0121] Slurry supply rate: 20 mL / min (sag)

[0122] Slurry temperature: 25℃

[0123] Substrate: SiC wafer (conductive type: n-type, crystalline 4H-SiC, offset angle of C-axis relative to main plane (0001): 4°) 2 inches

[0124] Grinding time: 1 minute

[0125] [Cleaning Test]

[0126] After polishing, the SiC wafer is removed from the grinding device and transferred to a clean room. At room temperature, it undergoes a 1-minute abrasive cleaning with running water (pure water) using a commercially available PVA (polyvinyl alcohol) sponge, followed by a 1-minute rinse with running water (pure water). Then, it is rinsed with running water (pure water) for at least 1 minute (overflow immersion).

[0127] [AFM Observation]

[0128] The surface (C-side) of the SiC wafer, which had been air-dried overnight in a clean room, was observed at three locations within a 10 μm × 10 μm area using an atomic force microscope (AFM; Bruker, model: Nanoscope V). The results confirmed the presence of particles adhering to the entire surface. The AFM image of the cleaned SiC wafer surface from Comparative Example 1 is shown below. Figure 1 .

[0129] <Example 1>

[0130] [Polishing Test]

[0131] Polishing tests were conducted using the same methods and conditions as in Comparative Example 1.

[0132] [Cleaning Test]

[0133] (Preparation of cleaning solution)

[0134] As surfactant A, sodium polyoxyethylene dodecyl ether sulfate (an aqueous solution with an average molar number of ethylene oxide addition: 3, alkyl carbon number: 12-14, concentration: 27%, stock solution pH: 8.6) was diluted 5 times with water (pure water) to obtain a cleaning solution.

[0135] (Cleaning)

[0136] The polished SiC wafer was removed from the grinding equipment and moved to a clean room. At room temperature, it underwent a 1-minute abrasive cleaning using a commercially available PVA sponge with running water (pure water). Next, it was immersed in the prepared cleaning solution for 1 minute of ultrasonic cleaning. Then, it was rinsed with running water (pure water) for 1 minute. Finally, it was rinsed with running water (pure water) for at least 1 minute (overflow immersion).

[0137] [AFM Observation]

[0138] Using the same method as Comparative Example 1, AFM observation was performed on the surface (C-side) of the cleaned SiC wafer. The results confirmed the presence of a small number of particles on the surface, but the particle count was significantly lower than in Comparative Example 1. It should be noted that the same applies to the Si-side. The AFM image of the cleaned SiC wafer surface from Example 1 is shown below. Figure 2 .

[0139] <Example 2>

[0140] [Polishing Test]

[0141] Polishing tests were conducted using the same methods and conditions as in Comparative Example 1.

[0142] [Cleaning Test]

[0143] (Preparation of cleaning solution)

[0144] As surfactant A, sodium polyoxyethylene dodecyl ether sulfate (an aqueous solution with an average molar number of ethylene oxide addition: 3, alkyl carbon number: 12-14, concentration: 27%; stock solution pH: 8.6) was prepared and used as a cleaning agent.

[0145] (Cleaning)

[0146] The polished SiC wafers were removed from the grinding equipment and transferred to a clean room. At room temperature, a 1-minute abrasive cleaning process using a commercially available PVA sponge and running water (pure water) was performed. For the wafers, a 1-minute abrasive cleaning was performed using a PVA sponge with the prepared cleaning agent. Following this, a 1-minute rinse with running water (pure water) was performed, followed by a rinse with running water (pure water) for at least 15 minutes (overflow immersion).

[0147] [AFM Observation]

[0148] Using the same method as in Comparative Example 1, AFM observation was performed on the surface (C-side) of the cleaned SiC wafer. No particles or other deposits were observed on the surface. It should be noted that the same applies to the Si-side. The AFM image of the cleaned SiC wafer surface from Example 2 is shown below. Figure 3 In addition, the Ra of the surface (C-plane) of the cleaned SiC wafer, measured using the above AFM, is 0.0497 nm and the Rmax is 8.54 nm.

[0149] <Example 3>

[0150] [Polishing Test]

[0151] Polishing tests were conducted using the same methods and conditions as in Comparative Example 1.

[0152] [Cleaning Test]

[0153] As surfactant B, a polyoxyethylene alkyl ether (ethylene oxide addition molar number: 9, alkyl group: isotridecyl (carbon number 13)) was prepared and used as a cleaning agent. The pH of this cleaning agent was 6.6. Cleaning was performed using this cleaning agent, except as described in Example 2.

[0154] [AFM Observation]

[0155] Using the same method as Comparative Example 1, AFM observation was performed on the surface (C-side) of the cleaned SiC wafer. The results showed particle adhesion on the surface, but less than in Comparative Example 1. Additionally, deposits other than particles were also observed. It should be noted that a small amount of particle adhesion and deposits other than particles were also observed on the Si surface. The AFM image of the cleaned SiC wafer surface of Example 3 is shown below. Figure 4 .

[0156] <Example 4>

[0157] [Polishing Test]

[0158] Polishing tests were conducted using the same methods and conditions as Comparative Example 1.

[0159] [Cleaning Test]

[0160] As surfactant C, alkyltrimethylammonium chloride (alkyl group: hexadecyl, stearyl group (carbon number 16-18)) was used to obtain an aqueous solution containing the above surfactant at a concentration of 28%. This was used as a cleaning agent. The pH of this cleaning agent was 7.1. Cleaning was performed using this cleaning agent, except that the method was the same as in Example 2.

[0161] [AFM Observation]

[0162] Using the same method as Comparative Example 1, AFM observation was performed on the surface (C-side) of the cleaned SiC wafer. A small amount of particle adhesion was observed on the surface, but the particle adhesion was significantly less than in Comparative Example 1. It should be noted that no particles were adhered to the Si-side. The AFM image of the cleaned SiC wafer surface from Example 4 is shown below. Figure 5 .

[0163] The results of Examples 1-4 and Comparative Example 1 are summarized in Table 1. In Table 1, the case with the best cleaning performance is marked with "◎", the case showing good cleaning performance is marked with "○", the case showing a certain cleaning effect is marked with "△", and the case with no cleaning effect is marked with "×".

[0164] [Table 1]

[0165] Table 1

[0166] Cleaning agent method Cleaning properties Example 1 Surfactant A Immersion ○ Example 2 Surfactant A frosted ◎ Example 3 Surfactant B frosted △ Example 4 Surfactant C frosted ○ Comparative Example 1 pure water frosted ×

[0167] Based on the above experimental results, it was confirmed that the cleaning agent containing surfactant has a cleaning effect on the polished SiC wafer.

[0168] The specific examples of the present invention have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations to the specific examples illustrated above.

Claims

1. A method for polishing and cleaning a substrate containing a material having a Vickers hardness of 1500 Hv or higher, the method comprising the following steps: The process of polishing a substrate using a polishing composition; and The process of cleaning the polished substrate using a cleaning agent. in, The polishing composition contains an abrasive aid. The cleaning agent contains anionic surfactants as surfactants. The anionic surfactant is a compound having an oxyalkylene unit and a hydrocarbon group. The hydrocarbon group has 12 or more carbon atoms. The material comprises diamond, sapphire, silicon carbide, boron carbide, tungsten carbide, silicon nitride, or titanium nitride.

2. The method of claim 1, wherein, The concentration of the surfactant in the cleaning agent is 1% by weight or more.

3. The method of claim 1 or 2, wherein, The cleaning agent also contains water.

4. The method of claim 1 or 2, wherein, The polishing composition contains non-diamond abrasive grains.

5. The method of claim 4, wherein, The non-diamond abrasive particles are silicon dioxide particles.

6. The method of claim 1 or 2, wherein, The substrate containing a material with a Vickers hardness of 1500 Hv or higher is a silicon carbide substrate.

7. A cleaning agent, which is the cleaning agent used in the method according to any one of claims 1 to 6. The cleaning agent contains anionic surfactants as surfactants. The anionic surfactant is a compound having an oxyalkylene unit and a hydrocarbon group. The hydrocarbon group has 12 or more carbon atoms.

8. A grinding and cleaning kit, which is the grinding and cleaning kit used in the method of any one of claims 1 to 6. The grinding and cleaning kit includes a polishing composition and a cleaning agent. The polishing composition comprises non-diamond abrasive grains and / or abrasive aids. The cleaning agent contains anionic surfactants as surfactants. The anionic surfactant is a compound having an oxyalkylene unit and a hydrocarbon group. The hydrocarbon group has 12 or more carbon atoms.

9. The kit for polishing and cleaning according to claim 8, wherein, The non-diamond abrasive particles are silicon dioxide particles.

10. A cleaning method for cleaning a silicon carbide substrate after polishing with non-diamond abrasives and / or abrasive aids. The method includes a step of cleaning the silicon carbide substrate using a cleaning agent. The cleaning agent contains anionic surfactants as surfactants. The anionic surfactant is a compound having an oxyalkylene unit and a hydrocarbon group. The hydrocarbon group has 12 or more carbon atoms.

11. The cleaning method according to claim 10, wherein, The non-diamond abrasive particles are silicon dioxide particles.

12. A cleaning agent for cleaning a silicon carbide substrate after polishing with non-diamond abrasives and / or abrasive aids, said cleaning agent comprising an anionic surfactant as the surfactant. The anionic surfactant is a compound having an oxyalkylene unit and a hydrocarbon group. The hydrocarbon group has 12 or more carbon atoms.

13. The cleaning agent of claim 12, wherein, The non-diamond abrasive particles are silicon dioxide particles.

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