TWI664278B - Abrasive composition for sapphire substrate - Google Patents

Abstract

The present invention provides an abrasive composition for a sapphire substrate that obtains a polishing surface with high polishing speed and high accuracy without surface defects such as scratches.

This composition contains inorganic abrasive material particles, a polishing accelerator, and water as components. The inorganic abrasive material particles are alumina particles, the polishing accelerator is an oxo acid salt, and the pH value is 9.0 to 13.0. The oxo acid salt is an alkali metal salt or an alkaline earth metal salt of an oxyacid of aluminum, silicon, or boron.

Description

Abrasive composition for sapphire substrate

The present invention relates to an abrasive composition, particularly an abrasive composition for sapphire.

Generally speaking, those referred to as hard and brittle materials include glass, ceramics, stone, semiconductor crystal materials, and the like. This kind of hard and brittle material is difficult to process, the grinding speed is slow, the material to be ground that requires longer processing time, and requires high quality polished surfaces with few flatness such as scratches or defects. A typical example of such a material to be polished is a sapphire substrate.

Sapphire substrates are mostly used for applications such as LED element substrates, and their production has increased in recent years. For example, LEDs are formed by coating a GaN film by CVD (chemical vapor deposition) on a sapphire substrate and depositing it. Sapphire is also used for the cover glass of a smartphone or tablet.

Regarding the manufacture of sapphire substrates, with the increase in demand and the expansion of the market, the demand for cheaper or higher quality has also increased, and competition in the industry has intensified. Sapphire is a very hard material that is chemically stable and has a Mohs hardness of 9, so cutting, grinding, and grinding are extremely difficult to perform, and processing takes an extremely long time. Various attempts have been made in the industry to reduce processing time and minimize costs. Previously, for sapphire wafers cut from sapphire ingots, after the grinding step of mechanically grinding diamond abrasive grains that are harder than sapphire from larger abrasive grains into smaller abrasive grains, silicon dioxide was used. Based abrasives, especially colloidal silicon dioxide based abrasives in the final polishing step to produce sapphire Substrate.

However, in these steps, there is a problem that production costs increase due to the use of expensive abrasives of diamond, or the processing time is prolonged due to multiple processing steps. Furthermore, since the processing is performed using a high-hardness diamond abrasive, the surface of the processed substrate is prone to scratches, and the inside of the substrate is prone to "latent damage" that cannot be confirmed by visual inspection. Therefore, it is difficult to perform LED substrates and the like. The problem of high quality processing required. Therefore, it is quite difficult to achieve the low-cost substrate required by the market, the cost reduction, and the high-quality processing.

Disclosed is an abrasive composition used in the polishing of a sapphire substrate to achieve both a higher polishing speed and a reduction in scratches or defects or an improvement in flatness.

Patent Document 1 discloses an abrasive for sapphire having an alkaline pH value containing a chlorine compound in an aqueous medium in which alumina particles, colloidal silica and the like are suspended. It is described as follows: The so-called chlorine compound refers to an alkali metal or alkaline earth metal salt of an acid, and the so-called acid refers to hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, ascorbic acid, oxalic acid, or picolinic acid. However, Patent Document 1 does not disclose the use of an alkali metal salt or an alkaline earth metal salt of an oxyacid of aluminum, silicon, or boron.

Patent Document 2 discloses an abrasive composition containing a composite abrasive particle of colloidal silica and alumina, and used for polishing an alumina substrate or the like. However, Patent Document 2 does not disclose the use of an alkali metal salt or an alkaline earth metal salt of an oxyacid of aluminum, silicon, or boron.

Patent Document 3 discloses an abrasive composition for polishing an aluminum-containing ceramic substrate containing a polishing agent containing alumina particles and an additive containing a phosphorus compound and having a pH value of about 8 or more. However, Patent Document 3 does not disclose the use of an alkali metal salt or an alkaline earth metal salt of an oxyacid of aluminum, silicon, or boron.

Patent Document 4 discloses a slurry for polishing sapphire containing alumina-containing abrasive particles having a pH range of 10.0 to 14.0. However, Patent Document 4 is about aluminum and silicon. The use of an alkali metal salt or an alkaline earth metal salt of boron oxyacid is not disclosed at all.

In Patent Document 5, as an abrasive composition for hard and brittle materials having a Vickers hardness of 1500 Hv or more, an abrasive composition containing alumina abrasive particles having a pH value of 8.5 or more and a surface area of 20 m ² / g or less is disclosed. Thing. However, Patent Document 5 does not disclose the use of an alkali metal salt or an alkaline earth metal salt of an oxyacid of aluminum, silicon, or boron.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2008-531319

[Patent Document 2] Japanese Patent Laid-Open No. 5-156238

[Patent Document 3] Japanese Patent Laid-Open No. 2011-62815

[Patent Document 4] International Publication No. 2011/136387

[Patent Document 5] International Publication No. 2012/115020

However, in Patent Document 1 in which colloidal silica is used for abrasive grains, although a good abrasive surface is obtained, a sufficient polishing rate is not obtained.

In Patent Documents 2 to 5, since alumina, which is a relatively hard particle, is used for the abrasive grains, although the polishing rate is increased, it is difficult to say that a sufficient polishing rate is obtained. Moreover, a highly accurate polished surface was not obtained after polishing.

The present invention has been made through intensive research in view of such a problem, and provides a polishing composition for a sapphire substrate which can obtain a high-precision polished surface with fewer scratches, a lower surface roughness, and a higher polishing rate.

In addition, it is possible to provide an abrasive composition which can be used not only for sapphire substrates, but also for hard and brittle materials such as hard glass substrates, crystal substrates, silicon or semiconductor substrates having the same problems as described above.

The present inventors have found that the above-mentioned problems can be solved by using an abrasive composition for a sapphire substrate which contains inorganic abrasive particles, a polishing accelerator, and water, and the inorganic abrasive particles It is alumina particles, and the grinding accelerator is an oxo acid salt with a pH value of 9.0 to 13.0. The oxo acid salt is an alkali metal salt or an alkaline earth metal salt of an oxyacid of aluminum, silicon, or boron. That is, the present invention relates to the following [1] to [18].

[1] An abrasive composition for a sapphire substrate, characterized in that it contains inorganic abrasive material particles, a polishing accelerator, and water, and the inorganic abrasive material particles are alumina particles, and the polishing accelerator is an oxo acid salt, The pH value is 9.0 ~ 13.0. The oxo acid salt is an alkali metal salt or an alkaline earth metal salt of aluminum, silicon or boron oxo acid.

[2] The abrasive composition for a sapphire substrate according to the above [1], wherein the oxo acid salt is sodium aluminate or potassium aluminate.

[3] The abrasive composition for a sapphire substrate according to the above [2], wherein the oxo acid salt is sodium aluminate.

[4] The abrasive composition for a sapphire substrate according to any one of the above [1] to [3], wherein the content of the oxo acid salt is 0.01 to 5% by mass relative to the mass of the abrasive composition for a sapphire substrate. .

[5] The abrasive composition for a sapphire substrate according to the above [4], wherein the content of the oxo acid salt is 0.01 to 2% by mass relative to the mass of the abrasive composition for a sapphire substrate.

[6] The abrasive composition for a sapphire substrate according to any one of the above [1] to [5], wherein the specific surface area of the alumina particles is 0.1 to 15 m ² / g.

[7] The abrasive composition for a sapphire substrate according to any one of the above [1] to [6], wherein the alumina particles are α alumina particles.

[8] The abrasive composition for a sapphire substrate according to any one of the above [1] to [7], wherein the D50 value of the alumina particles is 0.01 to 1.0 μm.

[9] The abrasive composition for a sapphire substrate according to any one of the above [1] to [8], wherein the alumina particles are boehmite Al ₂ O ₃ ‧H ₂ O and / or pseudo-boehmite Al ₂ O ₃ nH ₂ O (n = 1 ~ 2) is used as raw material for alumina.

[10] The abrasive composition for a sapphire substrate according to any one of the above [1] to [9], wherein the content of the alumina particles is 5 to 50% by mass relative to the mass of the abrasive composition for a sapphire substrate. .

[11] The abrasive composition for a sapphire substrate according to any one of the above [1] to [10], which further contains a dispersant.

[12] The abrasive composition for a sapphire substrate according to the above [11], wherein the dispersant is selected from the group consisting of a polycarboxylic acid (salt), a copolymer containing a repeating unit of a polycarboxylic acid (salt), and a condensed phosphate More than one of the group.

[13] The abrasive composition for a sapphire substrate according to the above [11] or [12], wherein the content of the dispersant is 0.005 to 0.5% by mass relative to the mass of the abrasive composition for a sapphire substrate.

[14] The abrasive composition for a sapphire substrate according to any one of the above [1] to [13], further comprising a dispersing aid, the dispersing aid being selected from the group consisting of alumina sol and cellulose At least one of the compounds.

[15] The abrasive composition for a sapphire substrate according to the above [14], wherein the alumina sol is one or more selected from the group consisting of a sol-forming composition of an aluminum salt and a boehmite sol.

[16] The abrasive composition for a sapphire substrate according to the above [14] or [15], wherein the content of the dispersion aid is 0.01 to 5% by mass relative to the mass of the abrasive composition for a sapphire substrate.

[17] A method for polishing a sapphire substrate, characterized in that the sapphire substrate is polished using the abrasive composition for a sapphire substrate according to any one of [1] to [16].

[18] A method for manufacturing a sapphire substrate, which includes using the above-mentioned [1] to [16] A step of polishing the abrasive composition for a sapphire substrate according to any one.

The abrasive composition of the present invention can perform grinding of hard and brittle materials such as sapphire substrates at high speed, and finally finish the polished surface into a high-quality polished surface state with high flatness and few scratches or defects. The abrasive composition of the present invention is particularly suitable for polishing a sapphire substrate.

In addition, the abrasive composition of the present invention can shorten the polishing time, and can polish a sapphire substrate or the like at a low cost.

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be made without departing from the scope of the invention.

The abrasive composition for a sapphire substrate of the present invention contains inorganic abrasive material particles, a polishing accelerator, and water. The inorganic abrasive material particles are alumina particles, the polishing accelerator is an oxy acid salt, and the pH value of the abrasive composition for a sapphire substrate. It is 9.0 ~ 13.0, and the above oxo acid salt is an alkali metal salt or an alkaline earth metal salt of aluminum, silicon, or boron oxo acid.

[Inorganic abrasive material particles]

The abrasive composition of the present invention includes inorganic abrasive particles, and the inorganic abrasive particles are alumina particles. To the inorganic abrasive material particles, silicon oxide, zircon, zirconia, cerium oxide, silicon nitride, silicon carbide, etc. may be added as necessary.

In general, as raw materials of alumina particles, gibbsite Al ₂ O ₃ ‧ 3H ₂ O, boehmite Al ₂ O ₃ ‧ H ₂ O, pseudo boehmite Al ₂ O ₃ ‧ nH ₂ O (n = 1 ~ 2), ammonium aluminium AlNH ₄ (SO ₄ ) ₂ ‧12H ₂ O, or aluminum salt of carbaminite NH ₄ AlCO ₃ (OH) ₂ etc. These alumina raw materials are prepared by the following method, for example.

(1) gibbsite Al ₂ O ₃ ‧ 3H ₂ O

It is obtained by dissolving bauxite in a hot solution of sodium hydroxide, cooling the solution obtained by removing the impurity components by filtration, and drying the resulting precipitate. This method is commonly referred to as the Bayer method.

(2) Boehmite Al ₂ O ₃ ‧H ₂ O

Obtained by hydrolyzing aluminum alkoxide Al (OR) ₃ obtained by the reaction of metal aluminum with alcohol. This method is commonly referred to as the aluminum alkoxide method.

(3) pseudo boehmite Al ₂ O ₃ ‧nH ₂ O (n = 1 ~ 2)

Obtained by treating gibbsite or bayerite with water vapor in an alkaline environment.

(4) Aluminum salt

For example, ammonium alum is obtained by cooling an aqueous solution of ammonium sulfate and aluminum sulfate and precipitating it from the solution. Sodium aluminite is obtained by reacting ammonium alum and ammonium carbonate.

Alumina is obtained by calcining or thermally decomposing these alumina raw materials. Alumina particles are obtained by pulverizing or classifying the obtained alumina. The alumina particles have various crystal forms such as α alumina, γ alumina, δ alumina, and θ alumina, and any crystal form can be used.

The raw material of the alumina particles used in the present invention is not particularly limited, and particularly preferred is boehmite Al ₂ O ₃ ‧H ₂ O and / or pseudo-boehmite Al ₂ O ₃ ‧nH ₂ O (n = 1 ~ 2) Alumina as raw material.

Compared with alumina particles prepared from other raw materials, alumina particles using boehmite or pseudo-boehmite as raw materials can obtain spherical and polycrystalline alumina particles, and relatively easy to obtain alumina particles of relatively high purity. In addition, during particle size preparation, it is easy to obtain fine particles with fewer coarse particles, narrow particle size distribution, and fewer angles.

Because it becomes alumina particles with such characteristics, if Alumina particles with pseudo boehmite as a raw material are used in the abrasive composition for a sapphire substrate of the present invention, so that scratches on the substrate are reduced, and a higher polishing speed can be obtained.

The D50 value (median diameter) of the inorganic abrasive material particles of the present invention is preferably 0.01 to 1.00 μm. If D50 is less than 0.01 μm, it becomes difficult to obtain a sufficient polishing rate. If it is more than 1.00 μm, scratches or latent injuries, deterioration of surface roughness, and reduction in flatness may deteriorate surface quality of the polished surface. . When D50 is larger than 1.00 μm, the dispersion stability (how long the particles can be dispersed in the aqueous medium without being precipitated) may be deteriorated. D50 is more preferably 0.10 to 0.90 μm, and still more preferably 0.20 to 0.70 μm.

D50 can be measured using a laser diffraction type particle size distribution measuring device (for example, Shimadzu Corporation, SALD2200). The so-called D50 refers to the particle size distribution measured on a volume basis using the laser diffraction method as the measuring principle. The measured particle size is accumulated from the smallest particle size to the starting point in the order of increasing particle size. The particle size is 50% of the volume of the particles. For example, the D50 of 0.45 μm means that the total volume of particles having a particle diameter of 0.45 μm or less accounts for 50% of the total volume of all the particles to be targeted.

The specific surface area of the inorganic abrasive material particles of the present invention is preferably 0.1 to 15 m ² / g. The specific surface area of the alumina abrasive particles gradually decreases due to the calcination or thermal decomposition of the alumina raw material, and can be adjusted according to the conditions of the calcination or thermal decomposition.

If the specific surface area is less than 0.1 m ² / g, the surface roughness may increase and the number of scratches may increase. If it is more than 15 m ² / g, it may become difficult to obtain a sufficient polishing rate. The specific surface area is more preferably 1 to 14 m ² / g.

The specific surface area can be measured as a BET value using an automatic flow-type specific surface area measurement device (for example, Shimadzu Corporation, Flowsorb II). The BET value refers to a specific surface area obtained by a BET method (gas adsorption method).

The crystal form of the alumina particles of the present invention is preferably alumina. If the alumina raw material is calcined or thermally decomposed, it will pass through crystal phases such as γ crystals, δ crystals, and θ crystals, and the crystal phases will be transformed. It is transferred to an α crystal which is a high-temperature stable phase. With the calcination or thermal decomposition, the hardness of the crystalline phase increases, and the size of the crystal particles also grows. Therefore, the crystalline phase can be adjusted according to the conditions of the calcination or thermal decomposition. For example, as described in paragraph 0021 of Japanese Patent No. 4290799, the alumina raw material crystal phase can be transferred to α crystals by supplying the alumina raw material to calcination or thermal decomposition at a temperature of 1000 ° C. or higher.

Since α alumina has a crystalline form with sufficient hardness, if α alumina particles are used in the abrasive composition of the present invention, a higher polishing rate will be obtained.

The content of the inorganic abrasive particles in the present invention is preferably 5 to 50% by mass based on the mass of the abrasive composition for a sapphire substrate. If the content is less than 5% by mass, it becomes difficult to obtain a sufficient polishing rate. Even if it is higher than 50% by mass, no further increase in the polishing rate is observed. This is not only uneconomical, but also the dispersion of the inorganic abrasive material particles deteriorates, and the abrasive composition Since the viscosity increases, the polishing rate may decrease, and the liquid-feeding resistance may increase when the abrasive composition is circulated, which may cause a problem. The content of the inorganic abrasive material particles is more preferably 5 to 20% by mass, and more preferably 8 to 15% by mass, relative to the mass of the abrasive composition for a sapphire substrate.

[pH value]

The pH value of the abrasive composition of the present invention is 9.0 to 13.0. The reason why the above-mentioned pH value is suitable for polishing the sapphire substrate is considered as follows.

The sapphire refers to single crystal alumina, and it is known that the surface of sapphire in water functions as a solid acid. Therefore, it is considered that when frictional heat is locally generated during polishing, sapphire is likely to cause a surface dissolution reaction with alkaline liquidity due to the frictional heat. It is considered that grinding is started by the dissolution reaction. If the pH value does not reach 9, the dissolution reaction does not start, and the reduction in the grinding speed is significant. Even if the value is greater than 13.0, no further increase in the grinding speed is seen, and it is dangerous during use.

The pH is more preferably 10.0 ~ 13.0.

[Grinding accelerator]

The polishing accelerator promotes the reaction on the surface of the sapphire substrate at a pH value of 9.0 to 13.0 of the polishing composition, and provides a higher polishing speed.

As the polishing accelerator, an alkali metal salt or an alkaline earth metal salt of an oxyacid of aluminum, silicon, or boron is used in the present invention. The polishing composition of the present invention may optionally be used in combination with an organic carboxylic acid chelating compound or an organic phosphonic acid chelating compound as a polishing accelerator.

It is considered that the so-called polishing accelerator of the present invention has the effect of promoting the removal of the deteriorated layer formed by the dissolution caused by the abrasive composition having a pH value of 9.0 to 13.0 on the surface of the sapphire substrate. The surface of the sapphire substrate is changed from the abrasive composition having a pH value of 9.0 to 13.0 to generate a deteriorated layer formed by dissolution. The deteriorated layer is removed by using a polishing accelerator, thereby polishing is performed and the polishing speed is increased.

[Oxide]

The oxo acid of the oxo acid salt used in the present invention is preferably an oxo acid of one or more elements selected from the group consisting of aluminum, silicon, and boron. Examples of the oxo acid salt include aluminate, silicate, aluminosilicate, and borate. Among these, aluminate is preferably used.

Preferably, the salt of the oxo acid salt used in the present invention is one or more salts selected from the group consisting of alkali metal salts and alkaline earth metal salts. Examples of the oxo acid salt include sodium salt, potassium salt, lithium salt, and calcium salt. Among these, a sodium salt or a potassium salt is preferably used.

More preferably, the oxo acid salt used in the present invention contains sodium aluminate or potassium aluminate, and most preferably contains sodium aluminate.

Oxyacids are well known and can be easily obtained on the market or can be prepared.

The content of the oxo acid salt is preferably in a range of 0.01 to 5% by mass based on the mass of the abrasive composition for a sapphire substrate. If it is less than 0.01% by mass, the effect of promoting the polishing rate is insufficient, and even if it exceeds 5% by mass, no further increase in the polishing rate is seen, which is not only uneconomical, but the dispersion may start to deteriorate. The content of the oxo acid salt is more preferably in the range of 0.01 to 2% by mass, and more preferably in the range of 0.1 to 1.5% by mass relative to the mass of the abrasive composition for a sapphire substrate.

[Chelating compound]

In the polishing agent composition of the present invention, a chelating compound may be optionally used in combination as a polishing accelerator. The chelate compound is preferably an organic carboxylic acid chelate compound or an organic phosphonic acid chelate compound.

From the viewpoint of setting the pH of the abrasive composition to 9.0 to 13.0, it is preferred that the organic phosphonic acid-based chelate compound and the organic carboxylic acid-based chelate compound form a salt with an alkali metal, ammonia, amine, or the like. . These salts can also be added to the abrasive composition by adding an organic phosphonic acid-based chelate compound or an organic carboxylic acid-based chelate compound and an alkali metal hydroxide, ammonia, or an amine to the abrasive composition, respectively. generate.

Examples of the organic phosphonic acid-based chelating compound include hydroxyethylene diphosphonic acid (HEDP), nitrogen trimethylene phosphonic acid (NTMP), and sodium, potassium, ammonium, and amine salts thereof. .

Examples of the organic carboxylic acid chelating compound include ethylenediaminetetraacetic acid (EDTA), nitrogen triacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), and hydroxyethylethylenediaminetetraacetic acid (HEDTA). ), Triethylenetetraaminehexaacetic acid (TTHA), hydroxyethyliminodiacetic acid (HIDA), dihydroxyethylglycine (DHEG), dicarboxymethylglutamic acid (GMGA), ethylenediamine- N, N "-disuccinic acid (EDDS) and the sodium, potassium, ammonium, amine and the like.

As the chelating compound, the aforementioned compounds may be used alone or in combination of two or more kinds. Preferred chelating compounds include tetrapotassium salt of ethylenediamine tetraacetate, trisodium salt of hydroxyethylethylenediamine tetraacetate, tetrasodium salt of hydroxyethylenediphosphonic acid, and azotrimethylenephosphonic acid Five sodium salts and so on.

Chelating compounds are well known and can be easily obtained on the market or prepared.

When the chelating compound is used as a polishing accelerator in combination, the content of the chelating compound is preferably in a range of 0.01 to 5% by mass relative to the mass of the polishing composition for a sapphire substrate. If it is less than 0.01% by mass, the effect of promoting the polishing rate is insufficient, and if it exceeds 5% by mass, the dispersibility may start to deteriorate. Relative content of chelating compounds The mass of the abrasive composition for a sapphire substrate is more preferably 0.01 to 2% by mass, and more preferably 0.1 to 1% by mass.

Aggregation of the inorganic abrasive material particles in the abrasive composition may cause deterioration of the polishing surface or deterioration of the polishing speed, which may cause damage or deterioration of the surface roughness.

[Dispersant]

In order to improve the dispersion state of the inorganic abrasive material particles and to solve the problems described above, a dispersant may be used in combination in the abrasive composition of the present invention.

Examples of the dispersant include a polymer-type dispersant, a surfactant-type dispersant, and an inorganic-type dispersant. In the abrasive composition of the present invention, a polymer dispersant and an inorganic dispersant are preferably used.

Examples of the polymer-type dispersant include polycarboxylic acid (salt), a copolymer containing a repeating unit of the polycarboxylic acid (salt), and the like, and examples of the inorganic-type dispersant include condensed phosphate.

Examples of the polycarboxylic acid (salt) include polyacrylic acid, polymethacrylic acid, polyacrylic acid alkali metal salt, polymethacrylic acid alkali metal salt, polyacrylic acid ammonium salt, polymethacrylic acid ammonium salt, polyacrylic acid amine salt, Polyamine methacrylate and the like.

Examples of the copolymer containing a repeating unit of a polycarboxylic acid (salt) include a copolymer of polyacrylic acid and a structural unit containing a sulfonic acid group, and a copolymer of polyacrylic acid and polyacrylate.

Examples of the condensed phosphate include sodium hexametaphosphate, sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, acidic sodium metaphosphate, and acidic sodium pyrophosphate.

The content of the dispersant is preferably in a range of 0.005 to 0.5% by mass based on the mass of the abrasive composition for a sapphire substrate. When it is less than 0.005 mass%, the effect of improving the dispersion state of the inorganic abrasive material particles is insufficient. Even if it exceeds 0.5 mass%, the effect of improving the dispersion state of the inorganic abrasive material particles reaches a limit, and it is not economical. The content of the dispersant is more preferably 0.01 to 0.5% by mass, more preferably 0.02 to 0.3% by mass, and most preferably 0.05 to 0.2% by mass relative to the mass of the abrasive composition for a sapphire substrate.

If the abrasive composition is left to stand in a state where the abrasive composition is stored in a bottle, precipitation of alumina abrasive particles may be caused. When the abrasive composition is used again, it may take time to make the dispersion state uniform again. In addition, in the polishing of a sapphire substrate or the like, the abrasive composition is generally supplied in a circulating manner when the abrasive composition is supplied to a polishing machine. In this case, precipitation of alumina abrasive particles may occur in the flow path of the abrasive composition, the storage tank of the abrasive composition, or the conveying pipe, and there is a possibility that the polishing speed may be reduced.

[Dispersion aid]

In order to solve the problem of precipitation or redispersion as described above, a dispersing aid may be used in combination in the abrasive composition of the present invention. Examples of the dispersing aid include alumina sol and cellulose. The reason why the dispersibility of the inorganic abrasive material particles is improved by adding a dispersion aid is presumed to be that the abrasive material particles are captured by a chemically-interactive network structure such as alumina sol or cellulose.

In addition, by adding a dispersing aid, the effect of increasing the grinding speed can also be seen.

The alumina sol refers to a product obtained by dispersing aluminum hydroxide or hydrated aluminum oxide in a colloidal state in an aqueous dispersion medium. Examples of the hydrated alumina include boehmite, pseudo-boehmite, gibbsite, gibbsite, and bayerite.

Examples of the alumina sol obtained by dispersing aluminum hydroxide in a colloidal state in an aqueous dispersion medium include a solization product of an aluminum salt.

The solization product of an aluminum salt is obtained by reacting an aluminum salt with a substance that easily reacts with water to form a hydroxyl group or a compound containing a hydroxyl group.

Examples of the aluminum salt used include aluminum sulfate, aluminum chloride, and aluminum nitrate. Examples of substances that easily react with the water used to form a hydroxyl group include ammonia or alkylamines, amine-based chelate compounds, aminocarboxylic acids, aminocarboxylic acid-based chelate compounds, and aminophosphonic acid-based chelate. Compounds etc. Examples of the compound containing a hydroxyl group include sodium hydroxide and potassium hydroxide.

Oxidation by dispersing hydrated alumina in colloidal form in an aqueous dispersion medium Examples of the aluminum sol include boehmite sol.

The boehmite sol is obtained by sol-gelating boehmite and / or pseudo-boehmite with an aluminum salt, an inorganic acid or an organic acid.

Examples of the aluminum salt used include aluminum sulfate, aluminum chloride, and aluminum nitrate. Examples of the inorganic acid used include nitric acid and hydrochloric acid. Examples of the organic acid used include acetic acid and gluconic acid.

The boehmite sol may be prepared by the above method, or a commercially available boehmite sol may be cured and dissolved in water to generate a boehmite sol during use.

Examples of celluloses include cellulose, crystalline cellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose.

As the dispersing aid used in the present invention, an alumina sol is preferable, and a solization product of an aluminum salt and a boehmite sol are more preferable.

The content of the dispersing assistant is preferably 0.01 to 5% by mass based on the mass of the abrasive composition for a sapphire substrate. If it is less than 0.01% by mass, the dispersion effect of the inorganic abrasive material particles cannot be sufficiently obtained. If it is more than 5% by mass, the viscosity of the abrasive composition may increase, which may cause an obstacle to recycling. In addition, if the content of the dispersing assistant is more than 5% by mass, the polishing rate may be reduced. More preferably, the content of the dispersion aid is 0.01 to 2% by mass based on the mass of the abrasive composition for a sapphire substrate.

[other]

The abrasive composition of the present invention may contain a pH adjuster in order to set a specific pH value. Examples of the pH adjusting agent include inorganic bases, organic bases, inorganic acids, and organic acids. Examples of the inorganic base include sodium hydroxide, potassium hydroxide, and ammonia. Examples of the organic base include tetramethylammonium hydroxide and alkanolamine. Examples of the inorganic acid include sulfuric acid, nitric acid, phosphoric acid, and hydrochloric acid. Examples of the organic acid include citric acid and malic acid.

In the abrasive composition of the present invention, if necessary, rust inhibitors, bactericides, detergents, surface modifiers, scratch reduction agents, viscosity modifiers, defoamers, antioxidants, and other purposes may be used in combination. Surfactants and so on.

The abrasive composition of the present invention can be prepared by mixing the ingredients.

The abrasive composition of the present invention can be used for polishing sapphire substrates, glass substrates, such as electronic component materials such as LED elements, optical components such as optical filters, electrical insulating materials, timepiece covers or window materials, wear-resistant materials, Used for crystal substrates, silicon or semiconductor substrates.

[Example]

Hereinafter, examples and comparative examples will be described in detail, but the present invention is not limited to those examples.

(1) Preparation method of abrasive composition

The alumina particles used in the examples and comparative examples were prepared by the following methods.

(Preparation example of alumina particles 1)

Commercially available boehmite alumina (CA alumina manufactured by Sasol) was calcined at 1160 ° C. for 9 hours so as to have a specific surface area of BET 4 m ² / g. The crystal form of the alumina after calcination is alpha alumina. The calcined product was wet-pulverized, and adjusted to D50 of 0.45 μm. The specific surface area of the prepared alumina particles was BET 10 m ² / g.

(Preparation example of alumina particles 2)

The commercially available alumina (APA-0.4AF manufactured by Sasol Corporation) having a crystalline form of alumina using boehmite alumina as a raw material was wet-pulverized, and D50 was adjusted to 0.35 μm. The specific surface area of the prepared alumina particles was BET 11 m ² / g.

The D50 of the alumina particles was measured using a laser diffraction particle size distribution measuring machine (manufactured by Shimadzu Corporation, SALD2200). The particle size distribution of the alumina particles is a volume basis.

The specific surface area of the alumina particles was measured using a flow-type specific surface area automatic measuring device (manufactured by Shimadzu Corporation, Flowsorb II).

The alumina sols used as dispersion aids in the examples and comparative examples were prepared by the following methods.

(Preparation example of alumina sol 1)

77 g of commercially available boehmite alumina (CA alumina manufactured by Sasol Corporation), 44 g of aluminum chloride, and 879 g of water were mixed and stirred with a homomixer to prepare a sol.

(Preparation example of alumina sol 2)

It was prepared by adding 100 g of a commercially available boehmite sol (Dispal23N4-80 manufactured by Sasol Corporation) to 888 g of water and thoroughly mixing and stirring to make it sol.

Alumina particles prepared by the above method as alumina abrasive particles, sodium aluminate as a grinding accelerator, tetrapotassium salt of ethylenediaminetetraacetic acid (EDTA-4K), and hydroxyethylene diphosphonic acid tetrahydrate were used. Sodium (HEDP-4Na), sodium hexametaphosphate as a dispersant, and an alumina sol prepared by the above method as a dispersing aid, the abrasive composition was prepared by the following method.

(Example 1)

Alumina particles 2 (D50: 0.35 μm, BET 11 m ² / g), sodium aluminate, and water were stirred and mixed so as to have the ratios in the table to prepare a polishing composition. In addition, the water system is added so that the remaining amount of other components may be removed from the composition. A polishing test was performed using the obtained abrasive composition.

(Example 2)

The alumina particles 2 (D50: 0.35 μm, BET 11 m ² / g), sodium aluminate, alumina sol 2 and water were stirred and mixed so as to have the ratios in the table to prepare an abrasive composition. In addition, the water system is added so that the remaining amount of other components may be removed from the composition. A polishing test was performed using the obtained abrasive composition.

(Example 3)

In the same manner as in Example 2, an abrasive composition was prepared. A polishing test was performed using the obtained abrasive composition.

(Example 4)

Alumina particles 2 (D50: 0.35 μm, BET 11 m ² / g), sodium aluminate, tetrapotassium salt of ethylenediaminetetraacetic acid (EDTA-4K), alumina sol 2 and water were used to make ratios in the table. The mixture is stirred and mixed to prepare an abrasive composition. In addition, the water system is added so that the remaining amount of other components may be removed from the composition. A polishing test was performed using the obtained abrasive composition.

(Example 5)

Alumina particles 1 (D50: 0.45 μm, BET 10 m ² / g), sodium aluminate, tetrasodium hydroxyethylene diphosphonic acid (HEDP-4Na), sodium hexametaphosphate (Hexameta), alumina sol 1 and Water was stirred and mixed so that it might become the ratio in a table | surface, and the abrasive composition was prepared. In addition, the water system is added so that the remaining amount of other components may be removed from the composition. A polishing test was performed using the obtained abrasive composition.

(Comparative example 1)

Alumina particles 2 (D50: 0.35 μm, BET 11 m ² / g) and water were stirred and mixed so as to have the ratios in the table to prepare a polishing composition. In addition, the water system is added so that the remaining amount of other components may be removed from the composition. A polishing test was performed using the obtained abrasive composition.

(Comparative example 2)

The alumina particles 2 (D50: 0.35 μm, BET 11 m ² / g), the alumina sol 2 and water were stirred and mixed so as to have the ratios in the table to prepare an abrasive composition, and sodium hydroxide was added to adjust it to The pH value in the table. In addition, the water system is added so that the remaining amount of other components may be removed from the composition. A polishing test was performed using the obtained abrasive composition.

(Comparative example 3)

Alumina particles 1 (D50: 0.45 μm, BET 10 m ² / g) and water were stirred and mixed so as to have the ratios in the table to prepare an abrasive composition, and sodium hydroxide was added to adjust the pH values in the table. . In addition, the water system is added so that the remaining amount of other components may be removed from the composition. A polishing test was performed using the obtained abrasive composition.

(Comparative Example 4)

Alumina particles 1 (D50: 0.45 μm, BET 10m ² / g), sodium hexametaphosphate (Hexameta), alumina sol 1 and water are stirred and mixed so as to have the ratios in the table to prepare an abrasive composition, Further, sodium hydroxide was added to adjust the pH value in the table. In addition, the water system is added so that the remaining amount of other components may be removed from the composition. A polishing test was performed using the obtained abrasive composition.

The description of the chelate compound in the table means the following.

EDTA-4K: Tetrapotassium salt of ethylenediamine tetraacetate

HEDP-4Na: Tetrasodium salt of hydroxyethylene diphosphonic acid

The description of the oxo acid salt in the table means the following.

Na aluminate: sodium aluminate

The description of the dispersant in the table means the following.

Hexameta: sodium hexametaphosphate

The description of the pH adjuster in the table means the following.

NaOH: sodium hydroxide

Using the obtained abrasive composition, the sapphire substrate was polished under the following polishing conditions.

(2) Grinding conditions

Grinder: Air-pressurized 6B double-sided grinder manufactured by SpeedFam

Polishing pad: SUBA-800 (made by Nitta Haas)

Fixed plate rotation: 60rpm lower, 20rpm upper

Load: 120g / cm ²

Grinding time: 420 minutes (7 hours)

Supply of abrasive composition: 120ml / min cycle

Grinding workpiece: 7.62cm (3 inches) sapphire wafer × 3P

(3) Evaluation of polished substrates

The evaluation of the polished substrate was performed by washing and drying the sapphire substrate polished by the method described above, and then using the following measuring method and measuring machine for evaluation.

(3-1) Grinding speed

According to the grinding speed [μm / hr] = (the mass before grinding of the sapphire substrate-the mass after grinding of the sapphire substrate) [g] ÷ the grinding area of the sapphire substrate [45cm ² ] ÷ the density of the sapphire substrate [3.98g / cm ³ ] ÷ The polishing time [420 minutes] × 10000 [μm / cm] × 60 [minutes / hr] was calculated and shown in the table.

(3-2) Surface roughness Ra

The surface roughness Ra of the sapphire substrate was measured using an atomic force microscope AFM (SPA-500 type manufactured by SII Technology) in a non-contact mode, a scanning rate of 1.0 Hz, and a field of view of 10 μm ² .

(3-3) Scratches

Observe the sapphire substrate with MICRO-MAX (VMX-2200Z-PL) manufactured by Tanaka Machine Sales and count the number of scratches.

The total number of scratches on both sides was 2 or less as Evaluation 1, the total was 3 as Evaluation 2, the total was 4 as Evaluation 3, and the total was 5 to 8 as Evaluation. 4. The sum of 9 or more is evaluated as 5.

(4) Evaluation of redispersibility of slurry

Regarding the redispersibility of the slurry, the prepared abrasive composition was evaluated by the following method.

Put 1kg of the abrasive composition in a 1L container, and let it stand still day and night. Turn the container upside down and shake it manually for 20 times. If the precipitated solid content in the slurry does not remain on the bottom surface, set it as Shendian residue. If there is a slight residue, it will be set as Shendian residue.

If Example 1 is compared with Comparative Example 1, Examples 2 and 3 and Comparative Example 2, it can be seen that a higher polishing rate can be obtained by adding an oxo acid salt as a polishing accelerator.

When Example 4 is compared with Examples 2 and 3, it can be seen that a higher polishing rate can be obtained if both a chelating compound and an oxo acid salt are included as a polishing accelerator.

[Industrial availability]

The present invention relates to polishing sapphire substrates, glass substrates, crystal substrates, silicon substrates, and the like used for polishing electronic components such as LED elements, optical components such as optical filters, electrical insulating materials, watch covers or windows, and abrasion-resistant materials Or a abrasive composition used for a semiconductor substrate or the like. The present invention is not limited to these uses, and can be used as other hard and brittle materials, etc. Abrasive composition.

In particular, the abrasive composition of the present invention is suitable for use in electronic component materials such as heat-resistant wafers for laser light emission, substrates for LED lighting, substrates for high-frequency power devices such as GaN on sapphire substrates, and liquid crystals. Polarizing element holding plates for projectors, light-transmitting optical parts and components used in cameras, electrical insulation materials, window materials for heat-resistant furnaces, sapphire tubes (protective tubes for thermocouples), and advanced smart phones as sapphire glass ( Multi-functional mobile phone) Cover glass, Camera protective lens, Touch ID sensor, Tablet PC (small plate-shaped portable information communication device), Cover glass (screen) of car navigation system, Touch ID sensor, etc. 2. Grinding of the sapphire substrate.

Claims (17)

A polishing composition for a sapphire substrate is characterized in that it contains inorganic polishing material particles, a polishing accelerator, and water, and the inorganic polishing material particles are alumina particles, the polishing accelerator is an oxo acid salt, and the pH is It is 9.0 ~ 13.0, and the above oxo acid salt is sodium aluminate or potassium aluminate. The abrasive composition for a sapphire substrate according to claim 1, wherein the oxo acid salt is sodium aluminate. For example, the abrasive composition for a sapphire substrate according to claim 1, wherein the content of the oxo acid salt is 0.01 to 5% by mass relative to the mass of the abrasive composition for a sapphire substrate. For example, the abrasive composition for a sapphire substrate according to claim 3, wherein the content of the oxo acid salt is 0.01 to 2% by mass relative to the mass of the abrasive composition for a sapphire substrate. The abrasive composition for a sapphire substrate according to claim 1, wherein the specific surface area of the alumina particles is 0.1 to 15 m ² / g. The abrasive composition for a sapphire substrate according to claim 1, wherein the alumina particles are alpha alumina particles. For example, the abrasive composition for a sapphire substrate of claim 1, wherein the D50 value of the alumina particles is 0.01 to 1.0 μm. For example, the abrasive composition for a sapphire substrate according to claim 1, wherein the alumina particles are boehmite Al ₂ O ₃ ‧H ₂ O and / or pseudo-boehmite Al ₂ O ₃ nH ₂ O (n = 1 ~ 2) Alumina as raw material. The abrasive composition for a sapphire substrate according to claim 1, wherein the content of the alumina particles is 5 to 50% by mass relative to the mass of the abrasive composition for a sapphire substrate. The abrasive composition for a sapphire substrate according to claim 1, further comprising a dispersant. The abrasive composition for a sapphire substrate according to claim 10, wherein the dispersant is selected from the group consisting of a polycarboxylic acid (salt), a copolymer containing a repeating unit of a polycarboxylic acid (salt), and a condensed phosphate. More than one. For example, the abrasive composition for a sapphire substrate according to claim 10, wherein the content of the dispersant is 0.005 to 0.5% by mass relative to the mass of the abrasive composition for a sapphire substrate. The abrasive composition for a sapphire substrate according to claim 1, further comprising a dispersing aid, the dispersing aid being at least one compound selected from the group consisting of alumina sol and cellulose. The abrasive composition for a sapphire substrate according to claim 13, wherein the alumina sol is one or more selected from the group consisting of a sol-forming composition of an aluminum salt and a boehmite sol. For example, the abrasive composition for a sapphire substrate according to claim 13, wherein the content of the dispersion aid is 0.01 to 5% by mass relative to the mass of the abrasive composition for a sapphire substrate. A method for polishing a sapphire substrate, which is characterized in that the sapphire substrate is polished using the abrasive composition for a sapphire substrate according to any one of claims 1 to 15. A method for manufacturing a sapphire substrate, comprising the step of polishing using the abrasive composition for a sapphire substrate according to any one of claims 1 to 15.