Polishing and cleaning methods, cleaning agents, and polishing and cleaning sets.

Abstract

To provide a method for effectively cleaning substrates made of high-hardness material after polishing. [Solution] A method is provided for polishing and cleaning a substrate made of a material having a Vickers hardness of 1500 Hv or more. This method includes the steps of: polishing the substrate to be polished using a polishing composition; and cleaning the polished substrate using a cleaning agent. Herein, the polishing composition includes an abrasive. The cleaning agent also includes a surfactant.

Description

Technical Field

[0001] The present invention relates to a polishing and cleaning method, a cleaning agent, and a polishing and cleaning set. More specifically, it relates to a method for polishing and cleaning a high-hardness material having a Vickers hardness of 1500 Hv or more, a cleaning agent used for the cleaning, a polishing and cleaning set, and a cleaning method. This application claims priority based on Japanese Patent Application No. 2020-164596 filed on September 30, 2020, and the entire contents of that application are incorporated herein by reference.

Background Art

[0002] The surface of a substrate made of a high-hardness material such as diamond, sapphire (aluminum oxide), silicon carbide, boron carbide, tungsten carbide, silicon nitride, titanium nitride, etc. is usually smoothed by polishing (lapping) performed by supplying diamond abrasive grains to a polishing platen. However, in lapping using diamond abrasive grains, scratches occur and those scratches remain, so there is a limit to improving surface smoothness. Therefore, after lapping using diamond abrasive grains or instead of such lapping, polishing (polishing) performed by supplying a polishing slurry between a polishing pad and the substrate using the polishing pad has been studied. Cleaning is carried out on the surface of the substrate on which such polishing has been performed for the purpose of removing deposits such as polishing debris and polishing components. As technical documents disclosing the cleaning of the substrate after polishing, for example, Patent Documents 1 to 4 can be cited.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] The substrate made of the above high-hardness material is finished to a high-quality surface by polishing. Regarding the cleaning process carried out after polishing, it is also desirable that the cleaning process can remove the deposits on the substrate surface and achieve a high-quality and clean surface. Regarding the cleaning of a substrate made of a high-hardness material, for example, in Patent Document 1, for the purpose of removing particles after diamond polishing, a silicon carbide substrate is cleaned using a low-concentration caustic surfactant (9 < pH < 12) mixed with deionized water in an ultrasonic cleaning tank. However, Patent Document 1 does not disclose polishing using a polishing aid. Also, as described above, polishing using diamond abrasive grains has limitations in improving surface quality, and it is difficult to achieve a satisfactory surface quality even after cleaning. Further, in Patent Document 2, a cleaning agent is used for the purpose of removing wax used for fixing the substrate. However, in Patent Document 2, evaluation using the substrate after polishing has not been performed, and the removability of deposits such as polishing debris and polishing components has not been examined.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method capable of satisfactorily cleaning a substrate made of a high-hardness material after polishing. Another related object is to provide a cleaning agent and a polishing and cleaning set used in the above method. Still another related object is to provide a method for cleaning the above substrate.

Means for Solving the Problems

[0006] This specification provides a method for polishing and cleaning a substrate made of a material having a Vickers hardness of 1500 Hv or more. This method comprises the steps of: polishing the substrate to be polished using a polishing composition; and cleaning the polished substrate using a cleaning agent. Here, the polishing composition includes non-diamond abrasive particles and / or polishing aids. The cleaning agent also includes a surfactant. According to the above method, by performing a polishing step using a polishing composition containing non-diamond abrasive particles followed by a cleaning step using a cleaning agent containing a surfactant, the substrate made of a high-hardness material is cleaned well. By using the above cleaning agent, a substrate with fewer deposits and high surface quality can be achieved.

[0007] In some preferred embodiments, the cleaning agent includes an anionic surfactant as the surfactant. A surfactant that exhibits good cleaning performance on a substrate made of a high-hardness material after polishing can be preferably selected from among anionic surfactants.

[0008] Examples of surfactants preferably used in the technologies disclosed herein include compounds having oxyalkylene units.

[0009] The concentration of the surfactant in the above-mentioned detergent is preferably 1% by weight or more. By increasing the concentration of the surfactant, the effect of adding the surfactant can be better exhibited, and a better cleaning effect can be suitably achieved.

[0010] In some embodiments, the detergent may contain water in addition to the surfactant. A detergent containing water (which may be a detergent solution) allows the surfactant to exert its effect more effectively.

[0011] In some preferred embodiments, the substrate made of a material having a Vickers hardness of 1500 Hv or more is a silicon carbide substrate. The effects of the technology disclosed herein are preferably exhibited in substrates made of silicon carbide.

[0012] Furthermore, this specification provides a cleaning agent for use in any of the methods disclosed herein. This cleaning agent comprises a surfactant. The cleaning agent having the above configuration can exhibit a good cleaning effect on substrates made of high-hardness material after polishing.

[0013] Furthermore, this specification provides a polishing and cleaning set comprising a polishing composition and a cleaning agent. This polishing and cleaning set is used in any of the methods disclosed herein. In the polishing and cleaning set, the polishing composition comprises non-diamond abrasive particles and / or polishing aids. The cleaning agent comprises a surfactant. By performing polishing and cleaning on a substrate made of a high-hardness material using a polishing and cleaning set with such a configuration, a substrate with high surface quality and a clean surface can be obtained.

[0014] Furthermore, this specification provides a method for cleaning a silicon carbide substrate after polishing with non-diamond abrasive particles. This cleaning method includes the step of cleaning the silicon carbide substrate with a cleaning agent, the cleaning agent comprising a surfactant. According to this cleaning method, a substrate made of a high-hardness material having a well-cleaned surface can be obtained. Polishing with non-diamond abrasive particles is preferably polishing using a polishing composition containing non-diamond abrasive particles.

[0015] Furthermore, this specification provides a method for cleaning a silicon carbide substrate after polishing with an abrasive. This cleaning method includes the step of cleaning the silicon carbide substrate with a cleaning agent, the cleaning agent comprising a surfactant. According to this cleaning method, a substrate made of a high-hardness material having a well-cleaned surface can be obtained. Polishing with an abrasive is preferably polishing using a polishing composition containing an abrasive.

[0016] According to the present specification, there is provided a cleaning agent used for cleaning a silicon carbide substrate after polishing using non-diamond abrasive grains. This cleaning agent contains a surfactant. The cleaning agent having the above configuration can exhibit a good cleaning effect on a substrate made of a high-hardness material after the above polishing. The polishing using non-diamond abrasive grains is preferably polishing using a polishing composition containing non-diamond abrasive grains.

[0017] According to the present specification, there is provided a cleaning agent used for cleaning a silicon carbide substrate after polishing using a polishing aid. This cleaning agent contains a surfactant. The cleaning agent having the above configuration can exhibit a good cleaning effect on a substrate made of a high-hardness material after the above polishing. The polishing using a polishing aid is preferably polishing using a polishing composition containing a polishing aid.

Brief Description of the Drawings

[0018] [Figure 1] It is an AFM image of the surface of a SiC wafer after cleaning according to Comparative Example 1. [Figure 2] It is an AFM image of the surface of a SiC wafer after cleaning according to Example 1. [Figure 3] It is an AFM image of the surface of a SiC wafer after cleaning according to Example 2. [Figure 4] It is an AFM image of the surface of a SiC wafer after cleaning according to Example 3. [Figure 5] It is an AFM image of the surface of a SiC wafer after cleaning according to Example 4.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The present invention can be implemented based on the content disclosed in the present specification and the common technical knowledge in the relevant field.

[0020] <Circuit board> The techniques disclosed herein encompass a method for cleaning a substrate made of a material having a Vickers hardness of 1500 Hv or more (also referred to as a high-hardness material), and more specifically, a method for cleaning a substrate made of the high-hardness material after polishing it. Therefore, the substrate made of the high-hardness material is both a substrate to be cleaned and a substrate to be polished. According to the methods disclosed herein, the surface of such a substrate made of high-hardness material is well cleaned. The Vickers hardness of the high-hardness material is preferably 1800 Hv or more (e.g., 2000 Hv or more, typically 2200 Hv or more). The upper limit of the Vickers hardness is not particularly limited, but may be approximately 7000 Hv or less (e.g., 5000 Hv or less, typically 3000 Hv or less). 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.

[0021] Materials having a Vickers hardness of 1500 Hv or higher include diamond, sapphire (aluminum oxide), silicon carbide, boron carbide, tungsten carbide, silicon nitride, and titanium nitride. The method disclosed herein can be applied to cleaning after polishing the single crystal surface of the above materials, which are mechanically and chemically stable. In particular, the substrate surface to be polished is preferably composed of silicon carbide. The carbon (C) surface of a silicon carbide substrate tends to be more difficult to remove polishing debris and polishing components from after polishing compared to the silicon (Si) surface, and 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. Improving its surface properties offers significant practical advantages, and there are also significant advantages to performing a cleaning treatment on a surface that has achieved high surface quality through polishing to finish it as a clean surface. The method disclosed herein is particularly preferably applied to the single crystal surface of silicon carbide.

[0022] <Cleaning agent> (Surfactants) The cleaning agent disclosed herein is used for cleaning substrates made of high-hardness material after polishing, and is characterized by containing a surfactant. Cleaning with a cleaning agent containing a surfactant can achieve a good cleaning effect on substrates made of high-hardness material after polishing. Specifically, it can remove particles and other deposits adhering to the surface of a substrate made of high-hardness material after polishing.

[0023] The surfactant used in the cleaning agent is not particularly limited, and any anionic, cationic, nonionic, or amphoteric surfactant can be used. A surfactant that exhibits good cleaning performance on the surface of a substrate made of a high-hardness material after polishing can be preferably selected from among anionic surfactants. Alternatively, nonionic surfactants are preferably used from the viewpoint of low foaming and ease of pH adjustment. Surfactants can be used individually or in combination of two or more.

[0024] Examples of anionic surfactants include sulfonic acid compounds such as alkanesulfonates, alkylbenzenesulfonates (e.g., nonylbenzenesulfonate, decylbenzenesulfonate, dodecylbenzenesulfonate, etc.), naphthalene sulfonates, alkyl sulfates (e.g., lauryl sulfate, octadecyl sulfate, etc.), polyoxyalkylene sulfates, α-olefin sulfonates, α-sulfo fatty acid salts, α-sulfo fatty acid alkyl ester salts, alkyl sulfosuccinates, and dialkyl sulfosuccinates; sulfate ester compounds such as alkyl sulfate esters, alkenyl sulfate esters, polyoxyalkylene alkyl ether sulfate esters (e.g., polyoxyethylene octadecyl ether sulfate, polyoxyethylene lauryl ether sulfate), and polyoxyalkylene alkenyl ether sulfate esters; carboxylic acid compounds such as alkyl ether carboxylates, amide ether carboxylates, sulfosuccinates, and amino acid-based surfactants; and phosphate ester compounds such as alkyl phosphate esters and alkyl ether phosphate esters. Among these, polyoxyalkylene alkyl ether sulfate esters are preferred. When an anionic surfactant forms a salt, the salt may 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 individually or in combination of two or more.

[0025] Examples of nonionic surfactants include oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyoxyalkylene derivatives such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene fatty acid esters, polyoxyethylene glyceryl ether fatty acid esters, and polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyalkylene adducts); and copolymers of multiple types of oxyalkylenes (e.g., diblock copolymers, triblock copolymers, random copolymers, alternating copolymers). Nonionic surfactants can be used individually or in combination of two or more types.

[0026] Examples of cationic surfactants include amine-type cationic surfactants such as alkylamidoamines and alkylamines; quaternary ammonium salt-type cationic surfactants such as tetraalkyl (1-4 carbon atoms) ammonium salts (e.g., tetramethylammonium salt), monolong-chain alkyl (8-18 carbon atoms) trishort-chain alkyl (1-2 carbon atoms) ammonium salts (e.g., lauryltrimethylammonium salt, palmityltrimethylammonium salt, stearyltrimethylammonium salt), and dilong-chain alkyl (8-18 carbon atoms) dishort-chain alkyl (1-2 carbon atoms) ammonium salts; and the like. When a cationic surfactant forms a salt, the salt may be, for example, a halide such as chlorine, bromine, or iodine; a hydroxide; or a sulfonic acid ester, sulfate ester, or nitrate ester with 1-5 carbon atoms. Among these, quaternary ammonium salt-type cationic surfactants (preferably monolong-chain alkyltrishort-chain alkylammonium salts, dilong-chain alkyldishort-chain alkylammonium salts, etc.) are preferred. Cationic surfactants can be used individually or in combination of two or more.

[0027] The amphoteric surfactant is not particularly limited and includes, for example, amine alkylene oxide type surfactants and amine oxide type surfactants. These can be used individually or in combination of two or more.

[0028] In some preferred embodiments, the surfactant (preferably anionic surfactant) may be a compound having an oxyalkylene unit. Typically, it may be a compound having a polyoxyalkylene structure. The oxyalkylene unit may consist of one oxyalkylene group or may be a repeating structure of two or more oxyalkylene units. Examples of oxyalkylene units include oxyethylene units (EO) and oxypropylene units (PO). Among these, oxyethylene units (EO) are preferred. If the surfactant has multiple oxyalkylene units, the oxyalkylene units may be of the same type (i.e., one type) or may consist of two or more types of oxyalkylene units. The total number of moles of alkylene oxide added to the surfactant may be 1 or more, 3 or more, 5 or more, 10 or more, 15 or more, 20 or more, 50 or less, 30 or less, 22 or less, 16 or less, 12 or less, 8 or less, or 4 or less (e.g., 3 or less).

[0029] Surfactants used in some embodiments (e.g., anionic surfactants) have a hydrocarbon group. The hydrocarbon group may be composed of saturated hydrocarbons such as alkyl groups, or it may contain unsaturated bonds such as carbon-carbon double bonds. Furthermore, the hydrocarbon group (typically alkyl groups) may be linear or branched. The number of carbon atoms in the hydrocarbon group (e.g., alkyl groups) may be 8 or more, 10 or more, 12 or more, 24 or less, 20 or less, 18 or less, 16 or less, or 12 or less. Specific examples of hydrocarbon groups (typically alkyl groups) include octyl groups, decyl groups, lauryl groups, myristyl groups, palmityl groups, stearyl groups, and the like.

[0030] The pH of the surfactant (pH of 100% by weight of the surfactant, or the pH of a commercially available surfactant (which may contain an appropriate amount of water, etc.)) is not particularly limited, but for example, 5.0 or higher is suitable, preferably 6.0 or higher (e.g., greater than 6.0), more preferably 6.5 or higher, even more preferably 7.0 or higher, and particularly preferably 7.5 or higher (e.g., greater than 8.0, and even more preferably 8.2 or higher). The pH of the surfactant is suitable to be less than 11.0, preferably less than 9.5, more preferably 9.0 or lower (e.g., less than 9.0), and may also be less than 8.0, less than 7.0, less than 6.0, or less than 5.0. High surface quality can be easily achieved by performing cleaning using a surfactant in the near-neutral range.

[0031] In this specification, the pH of liquid surfactants and detergents (typically cleaning solutions) can be determined by using a pH meter (for example, a glass electrode type hydrogen ion concentration indicator (model number F-23) manufactured by Horiba, Ltd.), performing a three-point calibration using standard buffers (phthalate pH buffer pH: 4.01 (25°C), neutral phosphate pH buffer pH: 6.86 (25°C), carbonate pH buffer pH: 10.01 (25°C)), then placing the glass electrode in the detergent to be measured and measuring the value after it has stabilized for at least two minutes.

[0032] The concentration of the surfactant in the detergent is appropriately set within a range in which the effect of the surfactant content is exerted, and is not limited to a specific range. The concentration of the surfactant in the detergent can be 0.01% by weight or more, and 0.1% by weight or more is appropriate. In some embodiments, the concentration of the surfactant in the detergent is 1% by weight or more, preferably 3% by weight or more, more preferably 10% by weight or more, even more preferably 20% by weight or more, and may be 30% by weight or more, or 40% by weight or more (e.g., 50% by weight or more). In such embodiments, the upper limit of the surfactant concentration in the detergent can be less than 90% by weight, may be less than 70% by weight, may be less than 50% by weight, or may be less than 35% by weight. Such a detergent may be in the form of a detergent solution containing a surfactant and water. In some other embodiments, the concentration of the surfactant in the detergent can be approximately 90% by weight or more (e.g., 90-100% by weight), 95% by weight or more is appropriate, and may be 99% by weight or more. Such a detergent may be substantially composed of surfactant.

[0033] (water) In some embodiments, the detergent contains water in addition to the surfactant. A detergent containing water allows the surfactant to exert its effect more effectively. Such a detergent may be a liquid detergent at room temperature. In this specification, room temperature refers to 23°C. Suitable water for use in the detergent includes deionized water, pure water, ultrapure water, and distilled water. The detergents disclosed herein may further contain, if necessary, an organic solvent (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water. Preferably, 90% or more by volume of the solvent in the detergent is water, and more preferably 95% or more by volume (e.g., 99-100% by volume) is water.

[0034] (Optional additives) The cleaning agents disclosed herein may further contain, if necessary, one or more known additives that can be used in cleaning agents, such as chelating agents, pH adjusters (acids or basic compounds, etc.), antioxidants, defoamers, preservatives, and fungicides.

[0035] Examples of chelating agents include aminocarboxylic acid-based chelating agents and organic phosphonic acid-based chelating agents. Examples of aminocarboxylic acid-based chelating agents include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetic acid, nitrilotriacetic acid, sodium nitrilotriacetate, ammonium nitrilotriacetate, hydroxyethylethylenediaminetriacetic acid, sodium hydroxyethylethylenediaminetriacetate, diethylenetriaminepentaacetic acid, sodium diethylenetriaminepentaacetate, triethylenetetraminehexaacetic acid, and sodium triethylenetetraminehexaacetate. Examples of organic phosphonic acid chelating agents include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetrakis(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-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 individually or in combination of two or more.

[0036] Furthermore, the detergents disclosed herein may be substantially free of chelating agents. Here, "substantially free of chelating agents" means that the concentration of chelating agents in the detergent is less than 1% by weight. The concentration of chelating agents in the detergent 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 also be preferably implemented in a form in which the detergent does not contain a chelating agent.

[0037] The content of the optional additives mentioned above can be within an appropriate range that does not significantly impede the effects of the present invention. For example, the content of the optional additives in the detergent is preferably less than 30% by weight, may be 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 is preferably carried out in a manner in which the detergent does not contain the optional additives. The optional additives are defined as components different from solvents such as water.

[0038] The amount of the above optional additive used can also be determined by its relative relationship to the surfactant. In detergents, the content of the optional additive per 1 part by weight of surfactant can be less than 3 parts by weight, and it is appropriate for it to be less than 1 part by weight. From the viewpoint of suitably exhibiting the effect of the surfactant, the content of the optional additive per 1 part by weight of surfactant may be, for example, less than 0.3 parts by weight, less than 0.1 parts by weight, less than 0.03 parts by weight, or less than 0.01 parts by weight. From the viewpoint of suitably exhibiting the effect of the additive, the content of the optional additive per 1 part by weight of surfactant can be 0.00001 parts by weight or more, 0.001 parts by weight or more is appropriate, it may be 0.1 parts by weight or more, it may be 0.5 parts by weight or more, or it may be 1 part by weight or more.

[0039] In some embodiments, the cleaning agent (which may be a cleaning solution) is substantially composed of a surfactant and water. Such a cleaning agent may be in the form of an aqueous solution of the surfactant. In this embodiment, the total proportion of surfactant and 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. Using a cleaning agent that is substantially composed of a surfactant and water in this way tends to allow the effect of the surfactant to be better exhibited.

[0040] (pH) The pH of the cleaning agent disclosed herein is not particularly limited. For example, the pH of the cleaning agent may 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, the pH of the cleaning agent is suitable at 5.0 or higher, preferably 6.0 or higher (e.g., greater than 6.0), may be 6.5 or higher, 7.0, 7.5 or higher, or 8.0 or higher. Also, the pH of the cleaning agent may be, for example, 13.0 or lower, 12.5 or lower, 12.0 or lower, or less than 12.0. In some embodiments, the pH of the cleaning agent may be, for example, less than 11.0, preferably less than 9.5, more preferably 9.0 or lower (e.g., less than 9.0), may be less than 8.0, less than 7.0, less than 6.0, or less than 5.0. High surface quality is easily achieved by performing cleaning using a cleaning agent in the near-neutral range.

[0041] <Cleaning method> The cleaning method disclosed herein includes a step (cleaning step) of cleaning a substrate made of a high-hardness material after polishing using a cleaning agent. The cleaning agent used is the cleaning agent described above. The cleaning method is not particularly limited and can be carried out by appropriate means depending on the purpose. For example, one or more cleaning processes selected from immersion cleaning, spray cleaning, scrubbing cleaning, ultrasonic cleaning, etc., can be employed. Scrub cleaning is preferred from the viewpoint of cleanability. Scrub cleaning refers to cleaning in which the substrate surface is wiped or rubbed using a cleaning tool such as a sponge, brush, or nonwoven fabric. For example, by applying a cleaning agent to the surface of a cleaning tool such as a sponge, brush, or nonwoven fabric, and bringing the cleaning tool with the cleaning agent applied into contact with the substrate surface and moving it relative to the surface, particles and other adhering matter attached to the substrate surface can be removed. Furthermore, from the viewpoint of removal of adhering particles, the cleaning step is preferably carried out before the substrate surface dries after polishing. The cleaning step disclosed herein may preferably be carried out in a manner that does not include ultrasonic cleaning or microwave cleaning.

[0042] From the viewpoint of removing adhering particles, scrubbing with a sponge (e.g., a 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 scrubbing), water (deionized water, pure water, ultrapure water, distilled water, etc.) or organic solvents (lower alcohols, lower ketones, etc.) may or may not be supplied to the substrate surface as needed.

[0043] The duration of the cleaning process using the cleaning agent is not particularly limited, but from the viewpoint of particle removal from the substrate surface, it is appropriate to set it to 10 seconds or more, preferably 30 seconds or more, and more preferably 1 minute or more. Also, from the viewpoint of cleaning efficiency, it is appropriate to set it to about 30 minutes or less, preferably 10 minutes or less, and more preferably 3 minutes or less (for example, 1 to 2 minutes).

[0044] The temperature of the detergent agent during the cleaning process can usually be room temperature (typically between 10°C and 40°C, for example, around 20-30°C). The detergent agent may also be heated (for example, to 40°C or higher, or around 50-80°C) before cleaning.

[0045] In some preferred embodiments, a pre-cleaning (also called a pre-wash) is performed before the cleaning step using the above-mentioned cleaning agent. Pre-cleaning is a cleaning method that does not use the above-mentioned cleaning agent, and may include one or more selected methods from, for example, immersion cleaning, running water cleaning, spray cleaning, scrubbing, ultrasonic cleaning, etc. For example, pre-cleaning may include immersion in water (deionized water, pure water, ultrapure water, distilled water, etc.; the same applies hereinafter unless otherwise specified), running water cleaning, spray cleaning with water, scrubbing with water, ultrasonic cleaning in a water tank, etc. Immersion in water may be batch immersion in which the substrate is immersed in a water tank, overflow immersion while water overflows into the tank, or quick-damp immersion. Scrub cleaning is preferred from the viewpoint of cleaning performance. Scrub cleaning with water is preferably performed while supplying water (running water) to the substrate surface. As for scrubbing in pre-cleaning, scrubbing using a sponge (e.g., a PVA sponge) is preferred. The pre-cleaning step is preferably performed before the substrate surface dries after polishing, from the viewpoint of removing adhering particles, and it is preferable to perform the cleaning step after the pre-cleaning step is completed but before the substrate surface dries. The water mentioned above may contain an appropriate amount of organic solvent (lower alcohol, lower ketone, etc.).

[0046] The duration of the pre-washing process is not particularly limited, but from the viewpoint of cleanability, it is appropriate to make it 10 seconds or longer, preferably 30 seconds or longer. Also, from the viewpoint of cleaning efficiency, it is appropriate to make it 10 minutes or less, preferably 3 minutes or less (for example, 1 to 2 minutes).

[0047] In some embodiments, a post-cleaning is performed after the cleaning step using the above-mentioned cleaning agent. The post-cleaning can be performed in the same manner as the pre-cleaning described above, except that it is performed after the cleaning step, so redundant explanations are omitted. In the post-cleaning, a method combining running water cleaning and immersion cleaning (e.g., overflow immersion) is preferably employed. When immersion cleaning is employed, the duration of the post-cleaning step should be at least 1 minute, and preferably at least 10 minutes (e.g., about 10 to 30 minutes).

[0048] The cleaning method disclosed herein can achieve a good cleaning effect on substrates made of high-hardness materials by using a surfactant and, in a preferred embodiment, by scrubbing with a sponge. Therefore, it can be preferably carried out in an embodiment that does not include ultrasonic cleaning or microwave cleaning, which are commonly used in conventional cleaning methods.

[0049] The surface roughness Ra of the substrate cleaned as described above is not particularly limited, but may be approximately 3 nm or less. The surface roughness Ra is preferably approximately 1 nm or less, more preferably approximately 0.3 nm or less, and even more preferably less than 0.10 nm (for example, about 0.01 to 0.07 nm). The Rmax of the substrate after cleaning 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 is achieved as described above. The above Ra and Rmax are measured using an atomic force microscope (AFM) as described in the examples below.

[0050] The substrate, made of the cleaned high-hardness material, is then dried by natural drying or forced drying using a dryer, and is preferably used as a semiconductor substrate material for various device applications such as optical devices and power devices.

[0051] <Manufacturing method for substrates> Furthermore, this specification provides a method for manufacturing a substrate made of a high-hardness material, including the above-mentioned cleaning method. The above-mentioned method for manufacturing a substrate is, for example, a method for manufacturing a silicon carbide substrate. The technologies disclosed herein may include a method for manufacturing a substrate made of a high-hardness material and a substrate made of a high-hardness material manufactured by the method. That is, according to the technologies disclosed herein, a method for manufacturing a substrate made of a high-hardness material and a substrate made of a high-hardness material manufactured by the method are provided, which includes a cleaning step of supplying any of the cleaning agents disclosed herein to a substrate made of a high-hardness material to clean the substrate. The above manufacturing method can be carried out by preferably applying the contents of any of the cleaning methods disclosed herein. According to the above manufacturing method, a clean substrate with improved surface quality, such as a silicon carbide substrate, can be efficiently provided.

[0052] Furthermore, a method for manufacturing a substrate made of a high-hardness material may include a step of polishing the substrate made of the high-hardness material to be polished (polishing step) before the cleaning step described above. Specifically, the polishing step is a step of polishing the surface of the substrate made of the high-hardness material using a polishing composition described later. The cleaning agent and cleaning method disclosed herein can suitably achieve the desired effect by being applied to a substrate made of the high-hardness material after polishing in the polishing step described later. The cleaning agent and cleaning method disclosed herein are preferably carried out in combination with the polishing described later. Therefore, according to this specification, a method for polishing and cleaning a substrate made of a high-hardness material is provided. The polishing composition and polishing method will be described below.

[0053] <Polishing Composition> (Abrasive grains) The polishing compositions disclosed herein typically contain abrasive grains. The inclusion of abrasive grains in the polishing composition is preferable from the viewpoint of efficiently achieving excellent smoothness. There are no particular limitations on the type of abrasive grains that may be included in the polishing composition. For example, the abrasive grains may be inorganic particles, organic particles, or organic-inorganic composite particles. Examples include 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; and abrasive grains substantially composed of any of these. The abrasive grains may be used individually or in combination of two or more types. 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 embodiments, alumina particles, zirconium oxide particles, chromium oxide particles, and iron oxide particles are more preferred, with alumina particles being particularly preferred. In other embodiments, silica particles, cerium oxide particles, and manganese dioxide particles are even more preferred, with silica particles being particularly preferred.

[0054] In this specification, the term "substantially composed of X" or "substantially made of X" for the composition of abrasive grains means that the proportion of X in the abrasive grains (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).

[0055] In some embodiments, alumina particles are used as abrasive grains. Alumina particles can be used alone or in combination of two or more types. When alumina particles are used as abrasive grains, it is generally advantageous for the proportion of alumina particles to the total abrasive grains contained in the polishing composition to be higher. For example, the proportion of alumina particles to the total 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., 95-100% by weight).

[0056] In some preferred embodiments, silica particles are used as abrasive grains. 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. Among these, colloidal silica is particularly preferred. The techniques disclosed herein are suitable for methods including polishing using a polishing composition containing silica particles. In polishing a substrate with silica particles, if the silica particles adhere to the substrate surface, their removal is often not as easy as with other particles. According to the techniques disclosed herein, such silica particles adhering to the substrate surface can be readily removed using the cleaning agent described above. Silica particles can be used individually or in combination of two or more types.

[0057] Abrasive grain A FIN When silica particles are used as abrasives, it is generally advantageous for the proportion of silica particles to the total abrasive grains in the polishing composition to be higher. For example, the proportion of silica particles to the total abrasive grains 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., 95-100% by weight).

[0058] Furthermore, the polishing compositions disclosed herein preferably use non-diamond abrasive grains that substantially do not contain diamond particles. Diamond particles have high hardness and can be a limiting factor in improving smoothness. Also, since diamond particles are generally expensive, they are not a cost-effective material, and from a practical standpoint, it is desirable to have a low degree of reliance on expensive materials such as diamond particles.

[0059] The average primary particle diameter of the abrasive grains (e.g., silica particles) is not particularly limited, but from the viewpoint of improving the polishing removal rate, it is 10 nm or more, more preferably 15 nm or more, even more preferably 20 nm or more, and may be 50 nm or more, or even 60 nm or more. A higher polishing removal rate can be achieved by increasing the average primary particle diameter. Also, from the viewpoint of surface quality after polishing, the above average primary particle diameter is usually 500 nm or less, and it is appropriate to set it to 300 nm or less, preferably 150 nm or less, more preferably 100 nm or less, even more preferably 80 nm or less, and may be, for example, 60 nm or less.

[0060] In the technology disclosed herein, the average primary particle diameter of the abrasive grains is calculated by taking the specific surface area (BET value) measured by the BET method and determining the average primary particle diameter (nm) = 6000 / (true density (g / cm³) 3 ) × BET value (m 2 This refers to the particle size (BET particle size) calculated by the formula ( / g). Specific surface area can be measured, for example, using a surface area measuring device manufactured by Micromeritex, product name "Flow Sorb II 2300".

[0061] When the polishing composition contains abrasive grains, the abrasive grain concentration in the polishing composition is usually appropriate to be 0.01% by weight or more from the viewpoint of polishing removal rate, but may also be 0.1% by weight or more, 1% by weight or more, or 3% by weight or more. From the viewpoint of efficiently improving smoothness, the abrasive grain concentration is preferably 10% by weight or more, and more preferably 20% by weight or more. Furthermore, from the viewpoint of obtaining good dispersibility, the abrasive grain concentration in the finishing polishing composition is usually appropriate to be 50% by weight or less, preferably 40% by weight or less, but may also be 20% by weight or less, 10% by weight or less, or 8% by weight or less. In some other embodiments, from the viewpoint of obtaining a desired surface quality, the polishing composition may not contain abrasive grains.

[0062] (Abrasive) The polishing compositions disclosed herein preferably contain polishing aids. Polishing aids are components that enhance the effect of polishing, and are typically water-soluble. While not interpreted as particularly restrictive, polishing aids are thought to contribute to polishing by abrasive grains by altering (typically through oxidation) the substrate surface during polishing, thereby weakening the substrate surface. For example, taking silicon carbide (SiC), one of the representative examples of high-hardness materials, as an example, in polishing, the polishing aid causes oxidation of SiC, i.e., SiO x C y It is thought to be contributing to the transformation. The relevant SiO x C y It has a lower hardness than SiC single crystal. Furthermore, in high-hardness materials with a Vickers hardness of 1500 Hv or higher, oxidation reactions can generally lead to a decrease in hardness and weakening. From these points, it is thought that the polishing removal rate and the surface quality of the substrate will improve by adding polishing aids.

[0063] Abrasives include peroxides such as hydrogen peroxide; nitric acid compounds such as nitric acid, its salts iron nitrate, silver nitrate, aluminum nitrate, and its complex cerium ammonium nitrate; persulfuric acid compounds such as potassium peroxomonosulfate and peroxodisulfate, their salts ammonium persulfate and potassium persulfate; chlorine compounds such as chloric acid and its salts, perchloric acid and its salt potassium perchlorate; bromine compounds such as bromate and its salt potassium bromate; iodine compounds such as iodic acid, its salt ammonium iodate, periodic acid, its salt sodium periodate and potassium periodate; and iron compounds such as iron acid and its salt potassium ferrate. Acids include: permanganic acid, its salts such as sodium permanganate and potassium permanganate; chromic acid, its salts such as potassium chromate and potassium dichromate; vanadic acid, its salts such as ammonium vanadate, sodium vanadate, and potassium vanadate; ruthenic acid, such as perruthenic acid or its salts; molybdic acid, its salts such as ammonium molybdate and disodium molybdate; rhenium acid, such as perrhenium or its salts; and tungstic acid, such as disodium tungstate. These may be used individually or in combination of two or more as appropriate. In some embodiments, permanganic acid or its salts, chromic acid or its salts, and iron acid or its salts are preferred, with sodium permanganate and potassium permanganate being particularly preferred. In some other embodiments, vanadic acid or its salts, iodine compounds, molybdic acid or its salts, tungstic acid or its salts are preferred, and sodium metavanadate, sodium vanadate, and potassium vanadate are particularly preferred.

[0064] In some preferred embodiments, the polishing composition contains a composite metal oxide as an abrasive. Examples of the composite metal oxide include metal nitrates, iron acids, permanganates, chromates, vanadates, ruthenic acids, molybdic acids, rhenic acids, and tungstic acids. Among these, iron acids, permanganates, chromates, vanadates, molybdic acids, and tungstic acids are more preferred, with permanganates and vanadates being even more preferred.

[0065] The polishing compositions disclosed herein may or may not further contain oxidizing agents other than the composite metal oxides described above. The techniques disclosed herein can preferably be carried out in a manner that includes the composite metal oxides and other oxidizing agents (e.g., hydrogen peroxide) as oxidizing agents. The techniques disclosed herein can also be carried out in a manner that substantially does not contain polishing aids other than the composite metal oxides (e.g., hydrogen peroxide) as polishing aids.

[0066] The content of polishing aids in a polishing composition is usually appropriate to be 0.005 mol / L or more. From the viewpoint of improving the polishing removal rate, the content of polishing aids in a polishing composition is preferably 0.008 mol / L or more, more preferably 0.01 mol / L or more, and may also 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 polishing aids in a polishing composition is usually appropriate to be 0.5 mol / L or less, preferably 0.3 mol / L or less, more preferably 0.2 mol / L or less, and may also be 0.1 mol / L or less, or 0.09 mol / L or less.

[0067] (Other ingredients) The polishing compositions disclosed herein may further contain, as necessary, known additives that can be used in polishing compositions (typically compositions for polishing high-hardness materials, such as compositions for polishing silicon carbide substrates), such as 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 fungicides, to the extent that they do not impair the effects of the present invention. The content of the above additives can be appropriately set according to their purpose of addition and does not characterize the present invention, so a detailed explanation is omitted.

[0068] (dispersion medium) The dispersion medium used in the polishing composition is not particularly limited, as long as it can disperse the abrasive particles. Deionized water, pure water, ultrapure water, distilled water, etc., can be preferably used as the dispersion medium. The polishing composition disclosed herein may further contain, if necessary, an organic solvent (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water. Generally, it is preferable that 90% or more by volume of the dispersion medium in the polishing composition is water, and more preferably 95% or more by volume (typically 99-100% by volume) is water.

[0069] The pH of the polishing composition is not particularly limited. Generally, a pH of 2 to 12 is appropriate. A practical polishing and removal rate is easily achieved when the pH of the polishing composition is within this range. The pH of the polishing composition is preferably 2 to 10, more preferably 3 to 9.5, and may also be 4 to 8. In some embodiments, the pH of the polishing composition may be, for example, 6 to 10 or 8.5 to 9.5.

[0070] The method for preparing the polishing composition disclosed herein is not particularly limited. For example, the components contained in the polishing composition may be mixed using a well-known mixing device such as a vane agitator, ultrasonic disperser, or homomixer. The manner in which these components are mixed is not particularly limited; for example, all components may be mixed at once, or they may be mixed in an order set as appropriate.

[0071] The polishing compositions disclosed herein may be mono-component or multi-component, including two-component types. For example, the polishing composition may be configured such that liquid A, containing some of the components, and liquid B, containing the remaining components, are stored separately, and liquids A and B are mixed together when polishing a substrate.

[0072] The polishing compositions disclosed herein may be in a concentrated form (i.e., in the form of a concentrated polishing solution) before being used for polishing. Polishing compositions in such a concentrated form are advantageous in terms of convenience and cost reduction during manufacturing, distribution, and storage.

[0073] <Polishing and cleaning set> Based on the above, this specification provides a polishing and cleaning set used for polishing and cleaning substrates made of high-hardness material. This polishing and cleaning set comprises a polishing composition and a cleaning agent. The polishing composition is used for polishing substrates made of high-hardness material, and the cleaning agent is used for cleaning the substrate made of high-hardness material after polishing with the polishing composition. More specifically, the polishing and cleaning set is used in a method for manufacturing a substrate made of high-hardness material. As the polishing composition, the polishing composition disclosed herein is used. As the cleaning agent, the cleaning agent disclosed herein is used. Specifically, the polishing composition may, for example, contain a polishing aid. It may also contain, for example, abrasive grains (preferably non-diamond abrasive grains). The cleaning agent also contains a surfactant. The polishing composition and the cleaning agent are typically stored separately from each other. A substrate manufactured using the polishing and cleaning set may have high surface quality after polishing and a clean surface after cleaning. Details of the polishing composition and cleaning agent are as described above, so a further explanation will be omitted.

[0074] <Polishing method> The polishing compositions disclosed herein can be used when polishing a substrate in an embodiment that includes, for example, the following operations: a polishing solution (slurry) containing one of the polishing compositions disclosed herein is prepared. Preparing the polishing solution may include adjusting the concentration of the polishing composition (e.g., diluting the polishing composition) or adjusting the pH of the polishing composition. Alternatively, the polishing composition may be used as is as the polishing solution. In the case of a multi-component polishing composition, preparing the polishing solution may include mixing the agents, diluting one or more agents before mixing, or diluting the mixture after mixing. The polishing solution is then supplied to the surface to be polished, and the surface is polished in a manner that is common to those skilled in the art. For example, the substrate is set in a general polishing apparatus, and the polishing solution is supplied to the surface to be polished of the substrate through the polishing pad of the apparatus. Typically, the polishing solution is supplied continuously, while the polishing pad is pressed against the surface to be polished of the substrate and the two are moved relative to each other (e.g., rotated). Polishing of the substrate is completed through this polishing process.

[0075] This specification provides a polishing method for polishing a substrate and a method for manufacturing a substrate using the polishing method. The polishing method is characterized by including a step of polishing the substrate using the polishing composition disclosed herein. The polishing method according to some preferred embodiments includes a step of performing pre-polishing (pre-polishing step) and a step of performing finish polishing (finish polishing step). In some preferred embodiments, the pre-polishing step is a polishing step that is placed immediately before the finish polishing step. The pre-polishing step may be a single polishing step or a multi-step polishing step of two or more stages. The finish polishing step, as used herein, is a step of performing finish polishing on a substrate that has been pre-polished, and is the last (i.e., furthest downstream) polishing step among the polishing steps that are performed using a polishing slurry containing abrasive particles. In a polishing method including a pre-polishing step and a finish polishing step as described herein, the polishing composition disclosed herein may be used in one step of the pre-polishing step, in the finish polishing step, or in both the pre-polishing step and the finish polishing step.

[0076] Pre-polishing and finish polishing can be performed using either a single-sided polishing device or a double-sided polishing device. In a single-sided polishing device, a substrate is attached to a ceramic plate with wax, the substrate is held using a holder called a carrier, and one side of the object to be polished is polished by pressing a polishing pad against one side of the substrate while supplying a polishing composition and moving the two relative to each other. The above movement is, for example, rotational movement. In a double-sided polishing device, the substrate is held using a holder called a carrier, and both sides of the substrate are polished simultaneously by pressing a polishing pad against the opposing sides of the substrate while supplying a polishing composition from above and rotating them in relative directions.

[0077] The polishing pads used in each polishing process disclosed herein are not particularly limited. For example, nonwoven fabric type, suede type, rigid foamed polyurethane type, abrasive-containing type, abrasive-free type, etc., may be used. In some embodiments, nonwoven fabric type or abrasive-free rigid foamed polyurethane type polishing pads may be preferred.

[0078] A substrate polished by the method disclosed herein is typically cleaned after polishing. The cleaning step is the cleaning method disclosed herein (a cleaning method using a cleaning agent containing a surfactant).

[0079] The polishing method disclosed herein may include any other steps in addition to the pre-polishing and finish-polishing steps described above. Such steps include mechanical polishing and lapping steps performed before the pre-polishing step. The mechanical polishing step involves polishing the substrate using a solution in which diamond abrasive particles are dispersed in a solvent. In some preferred embodiments, the dispersion does not contain an oxidizing agent. The lapping step involves polishing the substrate by pressing the surface of a polishing platen, such as a cast iron platen, against it. Therefore, no polishing pad is used in the lapping step. The lapping step is typically performed by supplying abrasive particles between the polishing platen and the substrate. The abrasive particles are typically diamond abrasive particles. The polishing method disclosed herein may also include additional steps before the pre-polishing step or between the pre-polishing step and the finish-polishing step. [Examples]

[0080] The following describes several embodiments of the present invention, but it is not intended to limit the present invention to those shown in the embodiments. In the following description, "%" refers to weight unless otherwise specified.

[0081] <Comparative Example 1> [Polishing Test] (Preparation of polishing composition) A polishing slurry was prepared by mixing colloidal silica as an abrasive, hydrogen peroxide and vanadic acid 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%.

[0082] (Polishing conditions) SiC wafers were prepared by first lapping them with diamond abrasive grains with an average particle size of 5 μm, and then pre-polishing them using a polishing solution containing alumina abrasive grains. Using the prepared polishing slurry, the surface of a pre-polished SiC wafer was polished under the following polishing conditions. Polishing equipment: Single-sided polishing equipment manufactured by Fujikoshi Machinery Industries, model "RDP-500" Polishing pad: Nitta Haas "SUBA800" Polishing pressure: 300g / cm² 2 Plate rotation speed: 80 revolutions / minute Head rotation speed: 40 revolutions / minute Slurry supply rate: 20 mL / min (flow-through) Slurry temperature: 25℃ Substrate: SiC wafer (conductivity type: n-type, crystalline type: 4H-SiC, off-angle of main surface (0001) relative to the C axis: 4°) 2 inches Polishing time: 1 minute

[0083] [Washing test] After polishing, the SiC wafers were removed from the polishing machine and moved to a cleanroom. At room temperature, they were scrubbed for 1 minute with running water (pure water) using a commercially available PVA (polyvinyl alcohol) sponge, followed by 1 minute of rinsing with running water (pure water). Further rinsing (overflow immersion) was performed with running water (pure water) for 15 minutes or more.

[0084] [AFM observation] The surface (C-plane) of a SiC wafer that had been air-dried overnight in a cleanroom was observed in three 10 μm × 10 μm areas using an atomic force microscope (AFM; Bruker, model: Nanoscope V), and particle adhesion was confirmed across the entire surface. Figure 1 shows the AFM image of the SiC wafer surface after cleaning according to Comparative Example 1.

[0085] <Example 1> [Polishing Test] A polishing test was performed using the same method and conditions as in Comparative Example 1.

[0086] [Washing test] (Preparation of cleaning solution) As surfactant A, sodium polyoxyethylene lauryl ether sulfate (ethylene oxide addition moles: average 3, alkyl group carbon numbers: 12-14, 27% aqueous solution; original solution pH: 8.6) was diluted five times with water (pure water) to obtain a washing solution.

[0087] (Washing) After polishing, the SiC wafer was removed from the polishing machine and moved to a cleanroom. At room temperature, it was scrubbed for 1 minute using a commercially available PVA sponge and running water (pure water). Next, it was immersed in the cleaning solution prepared above and ultrasonically cleaned for 1 minute. After that, it was rinsed with running water (pure water) for 1 minute. Finally, it was rinsed with running water (pure water) for 15 minutes or more (overflow immersion).

[0088] [AFM observation] AFM observation was performed on the surface (C-plane) of the SiC wafer after cleaning using the same method as in Comparative Example 1. A small amount of particles were found to be attached to the surface, but the amount of particle attachment was significantly less than in Comparative Example 1. The same was true for the Si-plane. Figure 2 shows the AFM image of the SiC wafer surface after cleaning according to Example 1.

[0089] <Example 2> [Polishing Test] A polishing test was performed using the same method and conditions as in Comparative Example 1.

[0090] [Washing test] (Preparation of cleaning solution) As surfactant A, sodium polyoxyethylene lauryl ether sulfate (ethylene oxide addition moles: average 3, alkyl group carbon numbers: 12-14, 27% aqueous solution; stock solution pH: 8.6) was prepared and used as a detergent.

[0091] (Washing) After polishing, the SiC wafer was removed from the polishing machine and moved to a cleanroom. At room temperature, it was scrubbed for 1 minute using a commercially available PVA sponge with running water (pure water). The wafer was then scrubbed for 1 minute using a PVA sponge coated with the prepared cleaning agent. Next, it was rinsed with running water (pure water) for 1 minute, followed by further rinsing with running water (pure water) for 15 minutes or more (overflow immersion).

[0092] [AFM observation] AFM observation was performed on the surface (C-plane) of the cleaned SiC wafer using the same method as in Comparative Example 1. No particles were found to be attached to the surface, and no other deposits were observed. The same was true for the Si-plane. Figure 3 shows the AFM image of the surface of the cleaned SiC wafer according to Example 2. Furthermore, the Ra of the surface (C-plane) of the cleaned SiC wafer measured using the above AFM was 0.0497 nm, and the Rmax was 8.54 nm.

[0093] <Example 3> [Polishing Test] A polishing test was performed using the same method and conditions as in Comparative Example 1.

[0094] [Washing test] As surfactant B, a polyoxyethylene alkyl ether (ethylene oxide addition moles: 9, alkyl group: isotridecyl group (13 carbon atoms)) was prepared and used as a detergent. The pH of this detergent was 6.6. Washing was performed in the same manner as in Example 2, except that this detergent was used.

[0095] [AFM observation] AFM observation was performed on the surface (C-plane) of the SiC wafer after cleaning using the same method as in Comparative Example 1. While particle adhesion was observed on the surface, the amount of particle adhesion was less than in Comparative Example 1. Other deposits were also observed. A small amount of particle adhesion was also observed on the Si-plane, along with other deposits. Figure 4 shows the AFM image of the SiC wafer surface after cleaning according to Example 3.

[0096] <Example 4> [Polishing Test] A polishing test was performed using the same method and conditions as in Comparative Example 1.

[0097] [Washing test] Alkyltrimethylammonium chloride (alkyl group: hexadecyl group, stearyl group (16-18 carbon atoms)) was used as surfactant C 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 in the same manner as in Example 2, except that this cleaning agent was used.

[0098] [AFM observation] AFM observation was performed on the surface (C-plane) of the SiC wafer after cleaning using the same method as in Comparative Example 1. A small amount of particles were found to be attached to the surface, but the amount of particle attachment was significantly less than in Comparative Example 1. No particles were found attached to the Si-plane. Figure 5 shows the AFM image of the SiC wafer surface after cleaning according to Example 4.

[0099] The results for Examples 1-4 and Comparative Example 1 are summarized in Table 1. In Table 1, the best cleaning performance is indicated by "◎", good cleaning performance by "〇", a certain level of cleaning effect is observed by "△", and no cleaning effect is observed by "×".

[0100] [Table 1]

[0101] The experimental results above confirmed that cleaning agents containing surfactants have a cleaning effect on SiC wafers after polishing.

[0102] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above.

Claims

1. A method for polishing and cleaning a substrate made of a material having a Vickers hardness of 1500 Hv or more, A step of polishing a substrate to be polished using a polishing composition; The polished substrate is cleaned using a cleaning agent; Includes, Here, The polishing composition includes an abrasive, The cleaning agent comprises a surfactant.

2. The method according to claim 1, wherein the cleaning agent comprises an anionic surfactant as the surfactant.

3. The method according to claim 1 or 2, wherein the surfactant is a compound having an oxyalkylene unit.

4. The method according to any one of claims 1 to 3, wherein the concentration of the surfactant in the detergent is 1% by weight or more.

5. The method according to any one of claims 1 to 4, further comprising water as the cleaning agent.

6. The method according to any one of claims 1 to 5, wherein the polishing composition comprises non-diamond abrasive particles.

7. The method according to any one of claims 1 to 6, wherein the substrate made of the material having a Vickers hardness of 1500 Hv or more is a silicon carbide substrate.

8. A cleaning agent used in the method according to any one of claims 1 to 7, A cleaning agent containing a surfactant.

9. A polishing and cleaning set used in the method described in any one of claims 1 to 7, A polishing composition and a cleaning agent are included. The polishing composition comprises non-diamond abrasive particles and / or polishing aids. The aforementioned cleaning agent is a polishing and cleaning set containing a surfactant.

10. A method for cleaning a silicon carbide substrate after polishing with non-diamond abrasive particles and / or polishing aids, The process includes cleaning the silicon carbide substrate using a cleaning agent, The cleaning agent includes a surfactant.

11. A cleaning agent used for cleaning a silicon carbide substrate after polishing with non-diamond abrasive particles and / or polishing aids, the cleaning agent comprising a surfactant.

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