JP6694745B2 - Polishing composition - Google Patents

Description

  The present invention relates to a polishing composition. Specifically, it relates to a polishing composition used for polishing a material to be polished.

  The surface of the material to be polished, such as diamond, sapphire (aluminum oxide), silicon carbide, boron carbide, tungsten carbide, silicon nitride, titanium nitride, etc., is usually polished (lapping) by supplying diamond abrasive grains to the polishing platen. Is processed. However, in lapping using diamond abrasive grains, defects and distortions are likely to occur due to scratch generation, remaining, and the like. Therefore, polishing (polishing) performed by supplying polishing slurry between the polishing pad and the object to be polished using a polishing pad after lapping with diamond abrasive grains or instead of the lapping has been studied. There is. Patent Documents 1 to 3 are mentioned as documents disclosing this type of conventional technique.

JP, 2011-121153, A JP 2012-248569 A JP, 2014-24154, A

  In the above-mentioned prior art documents, the polishing rate (amount of removing the surface of the polishing object per unit time) is devised by devising the components (abrasive grains, oxidizing agent, etc.) contained in the slurry (polishing composition) used for polishing. It has been proposed to improve surface flatness after polishing and polishing. However, even such a technique is not sufficient to satisfy the practically required levels regarding the polishing rate and the surface flatness, and there is still room for improvement.

  The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a polishing composition capable of achieving both a polishing rate and surface flatness at a high level. Another related object is to provide a method for producing an abrasive using the above polishing composition.

According to the present invention, there is provided a polishing composition used for polishing a material to be polished. This polishing composition contains diamond abrasive grains and non-diamond abrasive grains. Then, the ratio (B / A) of the content B of the non-diamond abrasive grains to the content A of the diamond abrasive grains on a weight basis is 2 <(B / A).
By using the diamond abrasive grains and the non-diamond abrasive grains in combination so as to have the above-mentioned specific content ratio, both the polishing rate and the surface flatness can be realized at a high level.

  In a preferred embodiment of the polishing composition disclosed herein, the ratio (B / A) is 100 ≦ (B / A) ≦ 2000. When the content ratio (B / A) is within such a range, compatibility between the polishing rate and the surface flatness can be more suitably exhibited.

In one preferred embodiment of the polishing composition disclosed herein, the average primary particle size D1 _A of the diamond abrasive grains is 10nm or less. Diamond abrasive grains having such average primary particle size D1 _A may effectively contribute to the balance of the polishing rate and surface flatness.

In a preferred embodiment of the polishing composition disclosed herein, the relationship between the average primary particle diameter D1 _A of the diamond abrasive grains and the average primary particle diameter D1 _B of the non-diamond abrasive grains is represented by the following formula: 1 <( D1 _B / D1 _A ) <500; By combining and using the diamond abrasive grains and the non-diamond abrasive grains so that the specific average primary particle diameter ratio is achieved, both the polishing rate and the surface flatness can be realized at a higher level.

  The technology disclosed herein is the zeta potential of the diamond abrasive grains at the pH of the polishing composition, and the zeta potential of at least one of the non-diamond abrasive grains and the material to be polished at the pH of the polishing composition. It can be preferably carried out in a mode in which the electric potential has a reverse polarity. Thus, at least one of the non-diamond abrasive grains and the material to be polished, by using the diamond abrasive grains having a zeta potential of the opposite polarity, compatibility between the polishing rate and the surface flatness is realized at a higher level. obtain.

  In a preferred embodiment of the polishing composition disclosed herein, the zeta potential of the diamond abrasive grains at the pH of the polishing composition, and the non-diamond abrasive grains and the material to be polished at the pH of the polishing composition. The zeta potential of is the opposite polarity. In a preferred embodiment, the zeta potential of the diamond abrasive grains at the pH of the polishing composition is positive, and the zeta potentials of the non-diamond abrasive grains and the material to be polished at the pH of the polishing composition are negative. It is sex. By setting the zeta potential of the diamond abrasive grains in the polishing composition to be positive, the above-mentioned effects can be better exhibited.

  In a preferred embodiment of the polishing composition disclosed herein, the material to be polished has a Vickers hardness of 1500 Hv or higher. In the polishing composition in which the material to be polished is a high hardness material, the application effect of the present invention can be more suitably exhibited.

  In a preferred embodiment of the polishing composition disclosed herein, the material to be polished is silicon carbide. In the polishing composition in which the material to be polished is silicon carbide, the application effect of the present invention can be more suitably exhibited.

  In a preferred aspect of the polishing composition disclosed herein, the non-diamond abrasive grains include silica particles. In the polishing using silica particles as the non-diamond abrasive particles, the effect of using a small amount of diamond abrasive particles in combination with the non-diamond abrasive particles can be better exhibited.

  Further, according to the present invention, a method for manufacturing an abrasive article is provided. The manufacturing method includes supplying any one of the polishing compositions disclosed herein to a polishing object to polish the polishing object. According to such a manufacturing method, it is possible to efficiently provide a polishing product having a surface after polishing having good surface flatness.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters particularly referred to in the present specification and matters necessary for carrying out the present invention can be understood as design matters for a person skilled in the art based on conventional technology in the field. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the field.

<Object to be polished>
The polishing composition disclosed herein can be applied to polishing objects to be polished made of various materials. The material to be polished is, for example, a metal or semimetal such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, stainless steel, germanium, or an alloy thereof; quartz glass, aluminosilicate glass, glassy carbon, etc. Glassy substance; ceramic material such as alumina, silica, sapphire, silicon nitride, tantalum nitride, titanium carbide; compound semiconductor substrate material such as silicon carbide, gallium nitride, gallium arsenide; resin material such as polyimide resin; obtain. The object to be polished may be composed of a plurality of materials among these. Above all, it is preferably used for polishing a high hardness material having a Vickers hardness of 1500 Hv or more. The Vickers hardness of the material to be polished is preferably 1800 Hv or higher (for example, 2000 Hv or higher, typically 2200 Hv or higher). The upper limit of the Vickers hardness is not particularly limited, but may be about 7,000 Hv or less (for example, 5000 Hv or less, typically 3000 Hv or less). In addition, in this specification, Vickers hardness can be measured based on JISR1610: 2003. The international standard corresponding to the above JIS standard is ISO 14705: 2000.

  Materials having a Vickers hardness of 1500 Hv or higher include diamond, sapphire (aluminum oxide), silicon carbide, boron carbide, zirconium carbide, tungsten carbide, silicon nitride, titanium nitride, gallium nitride, gallium arsenide, indium arsenide, and phosphide. Examples include indium and the like. The polishing composition disclosed herein can be preferably applied to a single crystal surface of the above-mentioned material which is mechanically and chemically stable. Above all, the surface of the object to be polished is preferably composed of silicon carbide. Silicon carbide is expected as a semiconductor substrate material with low power loss and excellent heat resistance. The practical advantages of improving its surface texture are particularly great. The polishing composition disclosed herein is particularly preferably applied to a silicon carbide single crystal surface.

<Polishing composition>
(Abrasive)
The polishing composition disclosed herein contains diamond abrasive grains and non-diamond abrasive grains. Then, the ratio (B / A) of the content B of the non-diamond abrasive grains to the content A of the diamond abrasive grains is 2 <(B / A) on a weight basis. By using the diamond abrasive grains and the non-diamond abrasive grains in combination in a specific content ratio in this manner, it is possible to achieve a high level of compatibility between the polishing rate and the surface flatness even for the surface of a high hardness material. .. The reason why such an effect is obtained is not particularly limited, but it can be considered as follows, for example. That is, in the polishing using a polishing composition containing a small amount of diamond abrasive grains with respect to non-diamond abrasive grains, by interposing high hardness diamond particles, the surface of the object to be polished while suppressing the surface roughness due to diamond particles The unevenness of is efficiently scraped (evened). This is considered to contribute to the improvement of the polishing rate and the surface flatness.

  The content ratio (B / A) of the diamond abrasive grains and the non-diamond abrasive grains in the polishing composition may be larger than 2 (that is, 2 <(B / A)). From the viewpoint of achieving both the polishing rate and the surface flatness, the content ratio (B / A) is appropriately 10 or more, and may be typically 50 or more, for example 100 or more. .. The polishing composition using the diamond abrasive grains and the non-diamond abrasive grains in combination so as to have such a content ratio (B / A) is disclosed herein by interposing an appropriate amount of diamond particles. The effects of applying the technology can be appropriately exerted. The upper limit of the content ratio (B / A) is not particularly limited, but can be, for example, 10000 or less, preferably 8000 or less, more preferably 5000 or less, further preferably 2000 or less, particularly preferably 1500 or less. .. The content ratio (B / A) may be, for example, 1000 or less, typically 500 or less, for example 300 or less. By reducing the content ratio (B / A), the polishing rate improving effect on the surface of the material to be polished can be realized at a higher level. In the technique disclosed herein, for example, the value (B / A) of the content ratio of the diamond abrasive grains and the non-diamond abrasive grains in the polishing composition is 100 or more and 10,000 or less (for example, 120 or more and 1500 or less, typically 150 or more and 300 or less).

  The diamond particles contained in the diamond abrasive grains may be various diamond particles containing diamond as a main component. Here, the diamond particles containing diamond as a main component are particles in which 90% by weight or more (usually 95% by weight or more, typically 98% by weight or more) of the particles are diamond. Examples of diamond particles that can be used include, but are not limited to, single crystal diamond, polycrystalline diamond, natural diamond, and synthetic diamond. Examples of the synthetic diamond mentioned here are diamond obtained by a static ultra-high pressure method (static pressure method) produced from graphite in a high temperature and high pressure metal solvent, and a dynamic ultra high pressure method (impact method) using high temperature and high pressure due to explosion. ), Diamond obtained by solidifying fine particles of single crystal diamond with a metal binder, and sintering the ultrahigh pressure. The diamond abrasive grains in the technique disclosed herein may contain one kind of such diamond particles alone or in combination of two or more kinds.

  The shape (outer shape) of the diamond abrasive grains may be spherical or non-spherical. Specific examples of the non-spherical diamond abrasive grains include a plate shape, a needle shape, and a spindle shape. In the technique disclosed herein, the diamond abrasive grains contained in the polishing composition may be in the form of primary particles or may be in the form of secondary particles in which a plurality of primary particles are associated. Further, the diamond abrasive grains in the form of primary particles and the diamond abrasive grains in the form of secondary particles may be mixed.

As the diamond abrasive grains, those having an average primary particle diameter (hereinafter sometimes simply referred to as “D1 _A ”) of 10 nm or less can be preferably adopted. From the viewpoints of surface flatness after polishing and increasing the number of particles per weight, D1 _{A of the} diamond abrasive grains is preferably 8 nm or less, more preferably 6 nm or less. The lower limit of D1 _A is not particularly limited, but it is suitable to be, for example, 0.1 nm or more, usually 0.3 nm or more, and typically 0.5 nm or more. From the viewpoint of polishing efficiency, D1 _A is preferably 1nm or more, more preferably 2nm or more. For example, a diamond abrasive grain having a D1 _A of 0.1 nm or more and 10 nm or less is preferable, a diamond abrasive grain of 1 nm or more and 8 nm or less is preferable, and a diamond abrasive grain of 2 nm or more and 6 nm or less is particularly preferable.

  As long as the content A of the diamond abrasive grains in the polishing composition (in the case of containing a plurality of types of diamond particles, the total content thereof) satisfies the above relationship with the content B of the non-diamond abrasive grains. Although not particularly limited, it is typically 0.001% by weight or more, preferably 0.01% by weight or more, and more preferably 0.05% by weight or more, from the viewpoint of shortening the processing time. Is more preferably 0.1% by weight or more. From the viewpoint of polishing stability and cost reduction, the content A of the diamond abrasive grains is usually 3% by weight or less, preferably 1% by weight or less, more preferably 0.5% by weight or less, More preferably, it is 0.2% by weight or less. In the technique disclosed herein, for example, the content A of diamond abrasive grains in the polishing composition is 0.005 wt% or more and 0.5 wt% or less (preferably 0.015 wt% or more and 0.2 wt% or less). Can be preferably carried out in an embodiment.

  The non-diamond particles contained in the non-diamond abrasive particles are not particularly limited as long as they are particles made of a material other than diamond. For example, the non-diamond particles can be any of inorganic particles, organic particles and organic-inorganic composite particles. For example, oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese oxide particles, zinc oxide particles, iron oxide particles; silicon nitride particles, nitriding particles. Abrasive grains substantially composed of any of nitride particles such as boron particles; carbide particles such as silicon carbide particles and boron carbide particles; carbonates such as calcium carbonate and barium carbonate; The non-diamond particles may be used alone or in combination of two or more. Of these, oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, zirconium oxide particles, manganese oxide particles, and iron oxide particles are preferable because they can efficiently form a good surface. Among them, silica particles, alumina particles, zirconium oxide particles, chromium oxide particles and iron oxide particles are more preferable, and silica particles, alumina particles and zirconium oxide particles are particularly preferable.

Suitable examples of non-diamond particles that can be used in the technology disclosed herein include silica particles. As the silica particles, colloidal silica, dry process silica and the like are preferably used. Examples of the dry process silica here include silica (fumed silica) obtained by burning a silane compound such as silicon tetrachloride or trichlorosilane in a hydrogen flame, or a reaction between metallic silicon and oxygen. The silica produced by the above is included. Examples of colloidal silica include silica produced using an alkali silicate-containing liquid (for example, sodium silicate-containing liquid) containing an alkali metal such as Na and K and SiO ₂ as a raw material, and tetraethoxysilane. And silica produced by a hydrolysis-condensation reaction of an alkoxysilane such as tetramethoxysilane (alkoxide method silica).

  When silica particles are used as the non-diamond particles, the proportion of silica particles in the entire non-diamond abrasive grains contained in the polishing composition is preferably 70% by weight or more. The technique disclosed herein can be preferably carried out in a mode in which the total proportion of silica particles in the total weight of the non-diamond abrasive grains contained in the polishing composition is greater than 85% by weight. The proportion of the silica particles is more preferably 95% by weight or more, further preferably 98% by weight or more, and particularly preferably 99% by weight or more. Above all, a polishing composition in which 100% by weight of the non-diamond abrasive grains contained in the polishing composition are silica particles is preferable.

  The shape (outer shape) of the non-diamond abrasive grains may be spherical or non-spherical. Specific examples of the non-spherical non-diamond abrasive grains include a peanut shape (that is, a peanut shell shape), a cocoon shape, a Konpeito sugar shape, and a rugby ball shape. In the technique disclosed herein, the non-diamond abrasive grains contained in the polishing composition may be in the form of primary particles or may be in the form of secondary particles in which a plurality of primary particles are associated. Further, the non-diamond abrasive grains in the form of primary particles and the non-diamond abrasive grains in the form of secondary particles may be mixed. In a preferred embodiment, at least some non-diamond abrasive grains are included in the polishing composition in the form of secondary particles.

As the non-diamond abrasive grains, those having an average primary particle diameter (hereinafter sometimes simply referred to as “D1 _B ”) of more than 10 nm can be preferably used. From the viewpoint of polishing efficiency, D1 _B is preferably 15nm or more, more preferably 20nm or more, more preferably 25nm or more, particularly preferably 30nm or more. The upper limit of D1 _B is not particularly limited, but it is suitable to be approximately 3000 nm or less, preferably 2000 nm or less, more preferably 800 nm or less. For example, D1 _B may be 500 nm or less (eg 300 nm or less), typically 200 nm or less (eg 130 nm or less), eg 110 nm or less (typically 80 nm or less). .. For example, non-diamond abrasive grains having a D1 _B of 12 nm or more and 80 nm or less are preferable, non-diamond abrasive grains of 15 nm or more and 60 nm or less are preferable, and 20 nm or more and 50 nm or less are preferable from the viewpoint of achieving both higher polishing efficiency and surface flatness. Those are particularly preferable. For example, non-diamond abrasive grains having D1 _B of 25 nm or more and 40 nm or less (for example, 35 nm or less) may be used.

In a preferred aspect, the non-diamond abrasive grain D1 _B is greater than the diamond abrasive grain D1 _A (ie, D1 _A <D1 _B ). As a result, the irregularities on the surface of the object to be polished can be eliminated more efficiently. For example, the relationship between D1 _A and D1 _B preferably satisfies 1 <(D1 _B / D1 _A ) <500, more preferably 2 <(D1 _B / D1 _A ) <200, and 2.5 ≦ It is more preferable to satisfy (D1 _B / D1 _A ) ≦ 50, and it is particularly preferable to satisfy 2.5 ≦ (D1 _B / D1 _A ) ≦ 20. By using the diamond abrasive grains and the non-diamond abrasive grains in combination so as to have a specific average primary particle diameter ratio, both the polishing rate and the surface flatness can be realized at a higher level. In the technology disclosed herein, for example, the relationship between D1 _A and D1 _B is 3 ≦ (D1 _B / D1 _A ) ≦ 12, more preferably 5 ≦ (D1 _B / D1 _A ) ≦ 10, and further preferably It can be preferably carried out in a mode where 5 ≦ (D1 _B / D1 _A ) ≦ 8.

From the viewpoint of better exerting the effect of the combined use of diamond abrasive grains and non-diamond abrasive grains, D1 _B is preferably larger than D1 _A by 10 nm or more. The value obtained by subtracting D1 _A from D1 _B (that is, D1 _B −D1 _A ) is preferably 60 nm or less, more preferably 50 nm or less, and further preferably 40 nm or less. For _example, D1 B -D1 _A is may be 30nm or less.

In the technique disclosed herein, the average primary particle diameter of the diamond abrasive grains and the non-diamond abrasive grains means the average primary particle diameter (nm) = 6000 / from the specific surface area (BET value) measured by the BET method. It refers to the particle size calculated by the formula (true density (g / cm ³ ) × BET value (m ² / g)). For example, when the non-diamond abrasive particles are silica abrasive particles (that is, abrasive particles composed of silica particles), the average primary particle diameter (nm) = 2727 / BET value (m ² / g) can be used to calculate the average primary particle diameter. it can. The specific surface area can be measured, for example, by using a surface area measuring device manufactured by Micromeritex Co., Ltd. under the trade name “Flow Sorb II 2300”.

  The content B of the non-diamond abrasive grains in the polishing composition (in the case of containing a plurality of types of particles, the total content thereof) is not particularly limited as long as the above relationship with the content A of the diamond abrasive grains is satisfied. Although not limited, from the viewpoint of polishing rate and the like, it is generally 1% by weight or more, preferably 5% by weight or more, more preferably 10% by weight or more, and further preferably 20% by weight or more. preferable. From the viewpoint of the surface flatness after polishing and the stability of polishing, the content B of the non-diamond abrasive particles is appropriately 50% by weight or less, preferably 45% by weight or less, more preferably 40% by weight or less. , And more preferably 30% by weight or less. The technique disclosed herein is preferably carried out in a mode in which the content B of the non-diamond abrasive grains in the polishing composition is 10% by weight or more and 40% by weight or less (preferably 20% by weight or more and 30% by weight or less). obtain.

  In a preferred embodiment, each of the diamond abrasive grains and the non-diamond abrasive grains has a zeta potential of the diamond abrasive grains at the pH of the polishing composition and a zeta potential of the non-diamond abrasive grains at the pH of the polishing composition have opposite polarities. Those having (reverse charge) can be appropriately selected and used. Further, the zeta potential of the diamond abrasive grains at the pH of the polishing composition and the zeta potential of the material to be polished at the pH of the polishing composition exhibit opposite polarities can be appropriately selected and used. In the technique disclosed herein, the zeta potential of the diamond abrasive grains at the pH of the polishing composition and the zeta potentials of both the non-diamond abrasive grains and the material to be polished at the pH of the polishing composition have opposite polarities. Can be preferably carried out. For example, when the zeta potentials of the non-diamond abrasive grains and the material to be polished show a negative polarity (minus), diamond abrasive grains exhibiting a positive polarity (plus) zeta potential can be preferably adopted. In this way, the diamond particles in the polishing composition are attracted to the non-diamond particles or the surface of the object to be polished by electrostatic attraction, and the state in which the diamond particles are present between the non-diamond particles and the surface of the object to be polished. It can be suitably realized. Therefore, the performance improving effect by using a small amount of diamond abrasive grains with respect to the non-diamond abrasive grains can be more suitably exhibited.

  The respective zeta potentials of the diamond abrasive grains, the non-diamond abrasive grains, and the material to be polished at the pH of the polishing composition are measured by, for example, the electrophoretic light scattering method or the electroacoustic spectroscopy, and are, for example, manufactured by Otsuka Electronics Co., Ltd. It can be measured using ELS-Z "or" DT-1200 "manufactured by Dispersion Technology Inc. The measurement of the zeta potential of the material to be polished can be replaced by the measurement of the zeta potential of fine particles made of the same material as the material to be polished. Alternatively, the surface of the material to be polished after immersing the material to be polished in a liquid containing fine particles having a known zeta potential, taking it out of the liquid and washing it with running water for about 10 seconds is used, for example, by using a scanning electron microscope. You may observe. In this case, the sign (polarity) of the value of the zeta potential of the material to be polished in the same liquid, that is, whether it is positive or negative can be known from the amount of fine particles attached to the surface of the material to be polished after cleaning. As a specific procedure, when the object to be measured is diamond abrasive grains or non-diamond abrasive grains, each abrasive grain is dispersed in pure water to prepare an aqueous solution for measurement having an abrasive grain concentration of 1 to 30% by weight. Then, after adjusting the pH to the same as that of the polishing composition with a pH adjuster (for example, potassium hydroxide, nitric acid, etc.), the zeta potential of each abrasive grain can be obtained using the zeta potential measuring device. When the object to be measured is a material to be polished, particles (powder material) made of the material to be polished are dispersed in pure water to prepare an aqueous solution for measurement having a particle concentration of 1 to 30% by weight. Then, after adjusting the pH to the same as that of the polishing composition with a pH adjuster (for example, potassium hydroxide, nitric acid, etc.), the zeta potential of the material to be polished can be determined using the zeta potential measuring device. The zeta potential of the diamond abrasive grains and the non-diamond abrasive grains can be adjusted, for example, by changing the material of the abrasive grains or modifying the surface of the abrasive grains (for example, organic functional group modification).

(Polishing aid)
The polishing composition disclosed herein preferably contains a polishing aid. The polishing aid is a component that enhances the effect of polishing, and a water-soluble one is typically used. Although the polishing aid is not particularly limited to interpretation, it exhibits an effect of deteriorating the polishing object surface in polishing (typically, oxidative alteration), and causes weakening of the surface of the polishing object. It is considered that it contributes to polishing by the abrasive grains.

  As the polishing aid, peroxides such as hydrogen peroxide; nitric acid, nitric acid compounds such as iron nitrate, silver nitrate, aluminum nitrate, nitric acid compounds such as cerium ammonium nitrate which is a complex thereof; potassium peroxomonosulfate, peroxodisulfate, etc. Persulfuric acid, its salts such as ammonium persulfate and potassium persulfate, persulfates; chloric acid and its salts, perchloric acid, its salts such as potassium perchlorate, chlorinated compounds; bromic acid and its salts Bromine compounds such as potassium bromate; iodic acid, its salts ammonium iodate, periodic acid, its salts sodium periodate, potassium periodate and other iodine compounds; ferric acid, its salts ferric acid Ferric acids such as potassium; permanganic acid, its salt sodium permanganate, potassium permanganate and other permanganic acids; chromic acid, its salts such as potassium chromate and potassium dichromate; vanadic acid , Its salts, vanadates such as ammonium vanadate, sodium vanadate, and potassium vanadate; ruthenic acids such as perruthenic acid or its salts; molybdic acid, its salts, ammonium molybdate, molybdenum such as disodium molybdate, etc. Examples thereof include acids; rhenic acids such as perrhenium or a salt thereof; tungstic acid such as tungstic acid and a salt thereof such as disodium tungstate. These may be used alone or in appropriate combination of two or more.

  In a preferred embodiment, the polishing composition contains a composite metal oxide as a polishing aid. Examples of the composite metal oxide include metal nitrates, ferric acids, permanganic acids, chromic acids, vanadic acids, ruthenic acids, molybdic acids, rhenic acids, and tungstic acids. Among them, vanadic acids, molybdic acids, and tungstic acids are more preferable, and vanadic acids are further preferable.

  In a further preferred embodiment, the complex metal oxide is a monovalent or divalent metal element (excluding transition metal elements) or ammonia, and a Group 5 or Group 6 transition metal element of the periodic table, A complex metal oxide CMO having is used. Suitable examples of the monovalent or divalent metal element (excluding transition metal elements) or ammonia include Na, K, Mg, Ca, and ammonia. Of these, Na and K are more preferable. The Group 5 or Group 6 transition metal element of the periodic table is preferably selected from the fourth period, the fifth period, and the sixth period, and is selected from the fourth period and the fifth period. Are more preferable, and it is still more preferable to be selected from the fourth period. The transition metal element is preferably selected from Group 5 elements. Specific examples thereof include V, Nb, Ta, Cr, Mo and W. Among them, V, Mo and W are more preferable, and V is further preferable.

  When the polishing composition disclosed herein contains a composite metal oxide (preferably a composite metal oxide CMO) as a polishing aid, the above-mentioned composite metal oxide (preferably a composite metal oxide is preferable as a polishing aid other than the composite metal oxide. Preferably further includes an oxygen-containing material capable of supplying oxygen to the composite metal oxide CMO). Thereby, the chemical action of the composite metal oxide (preferably the composite metal oxide CMO) is continuously exerted, the polishing efficiency in polishing is significantly improved, and the smoothness and flatness of the material to be polished are highly enhanced. Can be compatible. Preferable examples of the oxygen-containing material include hydrogen peroxide, ozone and peracid. Among them, hydrogen peroxide is particularly preferable.

  The concentration (content) of the polishing aid in the polishing composition is usually 0.1% by weight or more. The concentration is preferably 0.5% by weight or more, and more preferably 1% by weight or more (for example, 1.5% by weight or more), from the viewpoint of achieving both the polishing rate and the flatness highly and efficiently. Further, from the viewpoint of improving smoothness, the concentration of the above-mentioned polishing aid is usually appropriate to be 15% by weight or less, preferably 10% by weight or less, and 8% by weight or less (for example, 5% by weight). Or less, or 3% by weight or less) is more preferable.

  When a complex metal oxide (preferably complex metal oxide CMO) and an oxygen-containing substance capable of supplying oxygen to the metal oxide are used together as a polishing aid, the concentration of the complex metal oxide is Usually, it is appropriate that the amount is 0.1% by weight or more. The concentration is preferably 0.5% by weight or more, and more preferably 1.5% by weight or more, from the viewpoint of achieving both the polishing rate and the flatness highly efficiently. In addition, the concentration of the complex metal oxide is usually 10% by weight or less, preferably 3% by weight or less, and more preferably 2.5% by weight or less. In that case, the concentration of the oxygen-containing substance is usually 0.1 to 10% by weight, and the concentration is preferably 0.5 to 3% by weight from the viewpoint of preferably exhibiting the oxygen supply action. , 1 to 2% by weight is more preferable.

(Other ingredients)
The polishing composition disclosed herein is a chelating agent, a thickening agent, a dispersant, a surface protective agent, a wetting agent, a pH adjusting agent, a surfactant, an organic acid, an organic compound, as long as the effects of the present invention are not impaired. Acid salts, inorganic acids, inorganic acid salts, rust preventives, antiseptics, fungicides, etc. for polishing compositions (typically high hardness material polishing compositions such as silicon carbide substrate polishing compositions) If desired, known additives that can be used may be further contained. The content of the above-mentioned additive may be appropriately set according to the purpose of addition, and does not characterize the present invention, so a detailed description thereof will be omitted.

(solvent)
The solvent used in the polishing composition is not particularly limited as long as it can disperse the abrasive grains. As the solvent, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water or the like can be preferably used. The polishing composition disclosed herein may further contain an organic solvent (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water, if necessary. Usually, 90% by volume or more of the solvent contained in the polishing composition is preferably water, and more preferably 95% by volume or more (typically 99 to 100% by volume) is water.

  The pH of the polishing composition is usually suitable to be about 2-12. When the pH of the polishing composition is within the above range, a practical polishing rate is likely to be achieved. The pH of the polishing composition is preferably 3 to 11, and more preferably 4 to 10, from the viewpoint of better exerting the application effect of the technology disclosed herein.

<Preparation of polishing composition>
The method for producing the polishing composition disclosed herein is not particularly limited. For example, each component contained in the polishing composition may be mixed using a known mixing device such as a blade stirrer, an ultrasonic disperser, or a homomixer. The mode of mixing these components is not particularly limited, and for example, all components may be mixed at once, or may be mixed in an appropriately set order.

  The polishing composition disclosed herein may be a one-component type or a multi-component type including a two-component type. For example, a liquid A containing a part of the constituents of the polishing composition (typically, a component other than a solvent) and a liquid B containing the remaining components are mixed to polish an object to be polished. May be configured to be used for.

<Concentrated liquid>
The polishing composition disclosed herein may be in a concentrated form (that is, a concentrated liquid form of the polishing liquid) before being supplied to the object to be polished. The polishing composition in such a concentrated form is advantageous from the viewpoints of convenience and cost reduction during production, distribution, storage, and the like. The concentration ratio can be, for example, about 2 to 5 times in volume conversion.

  As described above, the polishing composition in the form of a concentrated solution can be used by diluting it at a desired timing to prepare a polishing solution and supplying the polishing solution to the object to be polished. The above-mentioned dilution can be typically carried out by adding the above-mentioned solvent to the above-mentioned concentrated liquid and mixing them. Further, when the solvent is a mixed solvent, only a part of the components of the solvent may be added to dilute, and a mixed solvent containing these components in an amount ratio different from that of the solvent is added. You may dilute it. Further, in a multi-component polishing composition as described below, a polishing liquid may be prepared by diluting a part of them and then mixing them with other agents, or by mixing a plurality of agents. After that, the mixture may be diluted to prepare a polishing liquid.

  The content of the abrasive grains in the concentrated liquid can be, for example, 70% by weight or less. From the viewpoint of stability of the polishing composition (for example, dispersion stability of abrasive grains) and filterability, the content is usually 60% by weight or less, and 50% by weight or less (eg 40% by weight or less). ). Further, from the viewpoint of convenience in manufacturing, distribution, storage, etc., cost reduction, etc., the content of abrasive grains can be, for example, 2% by weight or more, preferably 10% by weight or more, and more preferably 20% by weight or more. It is at least wt% (for example, at least 30 wt%).

<Polishing method>
The polishing composition disclosed herein can be used for polishing an object to be polished in a mode including the following operations, for example.
That is, a polishing liquid (slurry) containing any of the polishing compositions disclosed herein is prepared. Providing the polishing liquid may include preparing the polishing liquid by subjecting the polishing composition to operations such as concentration adjustment (for example, dilution) and pH adjustment. Alternatively, the polishing composition may be used as it is as a polishing liquid. Further, in the case of a multi-component type polishing composition, the preparation of the above-mentioned polishing liquid includes mixing the agents, diluting one or more agents before the mixing, and after the mixing. Diluting the mixture, etc. may be included.
Then, the polishing liquid is supplied to the surface of the object to be polished and polished by a conventional method. For example, the object to be polished is set in a general polishing apparatus, and the polishing liquid is supplied to the surface (surface to be polished) of the object to be polished through the polishing pad of the polishing apparatus. Typically, while continuously supplying the polishing liquid, the polishing pad is pressed against the surface of the object to be polished to relatively move (for example, rotationally move) them. The polishing of the object to be polished is completed through the polishing process.

  According to this specification, there are provided a polishing method for polishing a material to be polished and a method for manufacturing an abrasive article using the polishing method. The polishing method is characterized by including a step of polishing an object to be polished with the polishing composition disclosed herein. A polishing method according to a preferred aspect includes a step of performing preliminary polishing (preliminary polishing step) and a step of performing finish polishing (finish polishing step). The preliminary polishing step here is a step of performing preliminary polishing on an object to be polished. In a typical aspect, the preliminary polishing step is a polishing step that is placed immediately before the finish polishing step. The preliminary polishing step may be a single-step polishing step or a multi-step polishing step of two or more steps. Further, the finish polishing step here is a step of performing finish polishing on the object to be polished that has been preliminarily polished, and is the last of the polishing steps performed using the polishing slurry containing abrasive grains ( That is, it refers to the polishing step arranged on the most downstream side). Thus, in the polishing method including the preliminary polishing step and the finish polishing step, the polishing composition disclosed herein may be used in the preliminary polishing step, may be used in the finish polishing step, and may be used in the preliminary polishing step. It may be used in both the process and finish polishing steps.

  In a preferred embodiment, the polishing step using the polishing composition is a finish polishing step. Since the polishing composition disclosed herein can effectively reduce the surface roughness on the surface after polishing, the polishing composition used in the finishing polishing step of the surface of the material to be polished (composition for finishing polishing) Particularly preferably used as

  In another preferable embodiment, the polishing step using the polishing composition may be a preliminary polishing step. The polishing composition disclosed herein can realize a high polishing rate, and therefore is suitable as a polishing composition (preliminary polishing composition) used in the preliminary polishing step of the surface of the material to be polished. When the preliminary polishing step includes two or more polishing steps, it is possible to perform two or more polishing steps using any of the polishing compositions disclosed herein. .. The polishing composition disclosed herein can be preferably applied to pre-polishing in the former stage (upstream side). For example, it can be preferably used also in the first preliminary polishing step (typically, the primary polishing step) after the lapping step described later.

  Preliminary polishing and finish polishing can be applied to both polishing by a single-sided polishing device and polishing by a double-sided polishing device. In the single-sided polishing device, the object to be polished is attached to the ceramic plate with wax, or the object to be polished is held using a holder called a carrier, and the polishing pad is pressed against one side of the object to be polished while supplying the polishing composition. And relatively move (for example, rotationally move) both of them to polish one surface of the object to be polished. In a double-sided polishing apparatus, a polishing tool is held using a holder called a carrier, and a polishing composition is supplied from above, while pressing a polishing pad against the facing surface of the polishing object and rotating them in relative directions. By doing so, both sides of the object to be polished are simultaneously polished.

  The polishing pad used in each polishing step disclosed herein is not particularly limited. For example, any of a non-woven fabric type, a suede type, a rigid foamed polyurethane type, one containing abrasive grains, one containing no abrasive grains, etc. may be used.

  Abrasives polished by the methods disclosed herein are typically cleaned after polishing. This washing can be performed using an appropriate washing liquid. The cleaning liquid to be used is not particularly limited, and a known or commonly used cleaning liquid can be appropriately selected and used.

  The polishing method disclosed herein may include any other process in addition to the preliminary polishing process and the finish polishing process. Examples of such a process include a lapping process performed before the preliminary polishing process. The lapping step is a step of polishing the object to be polished by pressing the surface of the polishing table (for example, cast iron surface plate) against the object to be polished. Therefore, the polishing pad is not used in the lapping process. The lapping step is typically performed by supplying abrasive grains (typically diamond abrasive grains) between the polishing platen and the object to be polished. Further, the polishing method disclosed herein may include an additional step (cleaning step or polishing step) before the preliminary polishing step or between the preliminary polishing step and the finish polishing step.

<Method for manufacturing abrasives>
The technique disclosed herein may include a method for producing a polishing article (for example, a method for producing a silicon carbide substrate) including a polishing step using the above polishing composition, and provision of the polishing article produced by the method. .. That is, according to the technique disclosed herein, a polishing object composed of a material to be polished includes supplying any one of the polishing compositions disclosed herein to polish the polishing object. Provided are a method for producing an abrasive article and an abrasive article produced by the method. The above manufacturing method can be carried out by preferably applying the content of any of the polishing methods disclosed herein. According to the above-mentioned manufacturing method, it is possible to efficiently provide a polishing product (for example, a silicon carbide substrate) having a surface after polishing having good surface flatness.

  Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to the examples. In the following description, “%” is based on weight unless otherwise specified.

<Preparation of polishing composition>
(Example 1)
Diamond abrasive grains (average primary particle diameter: 4 nm), silica abrasive grains (average primary particle diameter: 33 nm) as non-diamond abrasive grains, sodium metavanadate (NaVO ₃ ) and hydrogen peroxide (H ₂ O) as polishing aids. ₂ ) and deionized water were mixed to prepare a polishing composition. The content A of diamond abrasive grains was 0.16%, the content B of silica abrasive grains was 24%, the content of NaVO ₃ was 1.8%, and the content of H ₂ O ₂ was 1.2%. The polishing composition had a pH of 6.5.

(Example 2)
A polishing composition was prepared in the same manner as in Example 1 except that the content A of the diamond abrasive grains was 0.082%.

(Example 3)
A polishing composition was prepared in the same manner as in Example 1 except that the content A of diamond abrasive grains was 0.016%.

(Comparative Example 1)
A polishing composition was prepared in the same manner as in Example 1 except that diamond abrasive grains were not used.

(Comparative example 2)
A polishing composition was prepared in the same manner as in Example 1 except that the content A of diamond abrasive grains was set to 0.25% and that silica abrasive grains were not used.

(Comparative example 3)
A polishing composition was prepared in the same manner as in Example 1 except that the content A of the diamond abrasive grains was 0.77% and the silica abrasive grains were not used.

<Evaluation of polishing rate>
Using the prepared polishing composition as it is as a polishing liquid, polishing was performed under the following conditions on the surface of a SiC wafer that had been preliminarily polished with a polishing liquid containing alumina abrasive grains. Then, the polishing rate was calculated according to the following calculation formulas (1) and (2). The results are shown in the relevant column of Table 1.
(1) Polishing allowance [cm] = Difference in weight of SiC wafer before and after polishing [g] / Density of SiC [g / cm ³ ] (= 3.21 g / cm ³ ) / Area to be polished [cm ² ] ( = 19.62 cm ² )
(2) Polishing rate [nm / h] = polishing allowance [cm] × 10 ⁷ / polishing time (= 1 hour)
[Policing conditions]
Polishing device: One-sided polishing device manufactured by Nippon Engis Co., model "EJ-380IN"
Polishing pad: "SUBA800" manufactured by Nitta Haas
Polishing pressure: 300 g / cm ²
Plate rotation speed: 80 rotations / minute Polishing time: 1 hour Head rotation speed: 40 rotations / minute Polishing liquid supply rate: 20 mL / minute (overflow)
Polishing liquid temperature: 25 ° C
Polishing object: SiC wafer (conductivity type: n type, crystal type 4H 4 ° off) 2 inches

  The diamond abrasive grains in the polishing composition used in the above polishing were "ELS-Z" manufactured by Otsuka Electronics Co., Ltd., and the zeta potentials of silica abrasive grains and SiC particles were measured by Dispersion Technology Inc. It was measured by the above-mentioned method using "DT-1200" manufactured by. As a result, it was confirmed that the zeta potential of the diamond abrasive grains has a positive polarity (plus) and the zeta potentials of the silica abrasive grains and the SiC particles have a negative polarity (minus).

<Surface roughness rms>
With respect to the surface of the polished article after polishing according to each example, a root-mean-square surface was used under the condition of a viewing angle of 5.6 mm × 4.2 mm, using a non-contact surface profilometer (trade name “NewView 5032”, manufactured by Zygo). The roughness rms (nm) was measured. The results are shown in the relevant column of Table 1.

  As shown in Table 1, according to the polishing compositions of Examples 1 to 3, in which the diamond abrasive grains and the non-diamond abrasive grains were combined in a specific content ratio, the surface roughness was achieved while realizing a high polishing rate. The surface of the polished product having a small rms was obtained. On the other hand, in Comparative Example 1 using only non-diamond abrasive grains, the surface roughness rms was large as compared with Examples 1 to 3, and the flatness of the surface of the polished object was lacking. Further, also in Comparative Examples 2 and 3 using only the diamond abrasive grains, the surface roughness rms was larger than that in Examples 1 to 3, and the flatness of the surface of the polished object was lacking. From this result, it was confirmed that both the polishing rate and the surface flatness can be realized by using the diamond abrasive grains and the non-diamond abrasive grains in combination in a specific content ratio.

  Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

Claims (9)

A polishing composition used for polishing a material to be polished, wherein the material to be polished is sapphire, silicon carbide, boron carbide, zirconium carbide, tungsten carbide, silicon nitride, titanium nitride, gallium nitride, gallium arsenide. , Indium arsenide, or indium phosphide,
Including diamond abrasive grains and non-diamond abrasive grains,
The average primary particle diameter D1 _{A of the} diamond abrasive grains is 10 nm or less,
On a weight basis, the ratio (B / A) of the content B of the non-diamond abrasive grains to the content A of the diamond abrasive grains is 2 <(B / A),
A polishing composition in which the zeta potential of the diamond abrasive grains at the pH of the polishing composition and the zeta potentials of the non-diamond abrasive grains and the material to be polished at the pH of the polishing composition have opposite polarities . A polishing composition used for polishing a material to be polished,
Including diamond abrasive grains and non-diamond abrasive grains,
On a weight basis, the ratio (B / A) of the content B of the non-diamond abrasive grains to the content A of the diamond abrasive grains is 2 <(B / A),
A polishing composition in which the zeta potential of the diamond abrasive grains at the pH of the polishing composition and the zeta potentials of the non-diamond abrasive grains and the material to be polished at the pH of the polishing composition have opposite polarities. The ratio (B / A) is a 100 ≦ (B / A) ≦ 2000, the polishing composition according to claim 1 or 2. Wherein the average primary particle size D1 _A diamond abrasive grains relationship between non-diamond abrasive grains having an average primary particle size D1 _B has the following _{formula: 1 <(D1 B / D1} A) <500; meet, claim 1 The polishing composition according to any one of to 3 . The zeta potential of the diamond abrasive grains at the pH of the polishing composition is positive,
The zeta potential of the in the pH of the polishing composition non-diamond abrasive grains and the polishing target material is negative, the polishing composition according to any one of claims 1-4. The polished material has a Vickers hardness of more than 1500 Hv, the polishing composition according to any one of claims 1-5. The polished material is silicon carbide, the polishing composition according to any one of claims 1-6. Examples non-diamond abrasive grains, including silica particles, the polishing composition according to any one of claims 1-7. By supplying a polishing composition according to any one of claims 1-8 to the object to be polished comprising polishing the polishing object, A method of making an abrasive product.