JP2000239652A - Precision polishing composition for hard and brittle materials and method for precision polishing of hard and brittle materials using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polishing composition which can polish the surface of a hard brittle material in high precision and can realize an excellent polishing efficiency and a long polishing life by dispersing in an aqueous medium α-alumina comprising microparticles having a specified or smaller mean particle diameter and a BET specific surface area in a specified range. SOLUTION: The α-alumina used comprises microparticles having a mean particle diameter (D50) of 0.3 μm or below, and a BET specific surface area of 15-50 m2/g. The α-alumina micropartieles used are desirably primary particles obtained by grinding a fired product made from boehmite and/or pseudo- boehmite and are desirably dispersed in an amount of 5-40 wt.%. It is desirable that the composition is adjusted to a pH of 8.5-12, and it is effective that silica particles are dispersed in the composition. The silica particles are desirably particles of colloidal silica, amorphous silicon dioxide, or fumed silica, and are dispersed in an amount of 45 wt.% or below, and it is desirable that the total amount of the α-alumina microparticles and the silica particles is at most 50 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision polishing composition for hard and brittle materials or a precision polishing material and a method for precisely polishing hard and brittle materials, and more particularly to a hard polishing material such as a lithium tantalate single crystal material and a lithium niobate single crystal material. The present invention relates to a precision polishing composition for hard and brittle materials (precision polishing material) used for precisely polishing the surface of a brittle material, and a method of using the same to advantageously precisely polish the hard and brittle material. is there.

[0002]

2. Description of the Related Art A surface acoustic wave device using a surface acoustic wave generated by a piezoelectric effect in a piezoelectric material has been widely used as an electronic component such as an intermediate frequency filter and a resonator of a television. In addition, as a material of a piezoelectric wafer constituting such a surface acoustic wave device, various kinds of piezoelectric substances such as piezoelectric ceramics and piezoelectric thin films have been studied. In particular, in recent years, lithium tantalate single crystal materials have been studied. And brittle materials such as lithium niobate single crystal materials
Since it has excellent characteristics in terms of the electro-optic effect, it is widely used as a wafer material.

[0003] In the surface acoustic wave device wafer made of such a hard and brittle material, the surface on which the electrodes are to be photo-printed is usually subjected to precision polishing so that the surface is mirror-finished. It is, specifically,
Using a platen on which a polishing cloth made of polyurethane or the like is stuck,
While rotating such a platen, while supplying a slurry-like abrasive on the polishing cloth surface, by pressing the wafer as a workpiece material against the polishing cloth surface, so that the wafer surface is polished, Thus, precision polishing is performed.

The abrasive used in the precision polishing is, of course, one capable of highly precisely polishing the surface of a material to be processed (wafer).
It is desired that the polishing efficiency or the polishing rate be excellent. Moreover, such an abrasive is generally used repeatedly by circulating a certain amount thereof for economic reasons (so-called circulating supply system). Depending on the decrease in efficiency, every predetermined time, a part of the abrasive is replaced with a new abrasive, or,
Since the necessity of replacing all of them with new ones after a predetermined polishing time has inevitably arises, the polishing efficiency (speed) can be maintained constant for a long time, in other words, the polishing life is good. Is required.

[0005] By the way, hard brittle materials such as lithium tantalate single crystal material used as a wafer material as described above are chemically stable materials, have extremely low polishing effect by mechanochemical action, and have low hardness. Since the abrasive is high, as the abrasive, it is possible to use a hard abrasive such as alumina and diamond having coarse and hard properties used in normal finish polishing, such as diamond. However, since the polishing efficiency is good, the polishing process can be easily performed, but there is a problem that the processing distortion remains in the wafer and the surface accuracy is significantly deteriorated. Therefore, practical application was extremely difficult.

Therefore, in the precision polishing (polishing) process in the industrial production of wafers as described above,
Conventionally, Japanese Patent Application Laid-Open Nos.
Japanese Patent Application Laid-Open No. 2-30303, Japanese Patent Application Laid-Open No. 5-154760 and the like disclose a polishing agent for a silicon wafer containing colloidal silica (colloidal silicon dioxide) as an essential solid component to a wafer made of a hard and brittle material. Applied techniques have been adopted. Such a colloidal silica abrasive has a feature that the accuracy of the polished surface can be highly achieved, but it is difficult to say that the polishing efficiency (polishing speed) is sufficient and shortens the polishing time. As described above, this is a major obstacle, and also causes a problem that the polishing efficiency (speed) is significantly reduced as the polishing time elapses. In such a case, the necessity of frequently changing the abrasive material has arisen, so that the work efficiency and workability are deteriorated, and the cost of the abrasive material and equipment is increased. There was a problem such as doing.

To cope with such a problem, Japanese Unexamined Patent Publication (Kokai) No. 5-1279 discloses a fine surface abrasive for hard and brittle materials having a BET specific surface area of 10 to 60 m ² / cm ² .
g, and an aqueous slurry dispersion containing only finely divided silicon dioxide having a secondary particle average particle diameter of 0.5 to 5 μm as a solid component has been proposed. Also, compared to colloidal silica abrasives, it has the advantage of exhibiting a somewhat improved polishing life, but even with such abrasives,
There is still room for improvement in polishing efficiency (speed).

[0008]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for precisely polishing hard and brittle materials, which is used for hard and brittle materials. A precision polishing composition or material for hard and brittle materials capable of polishing a surface with high precision and realizing excellent polishing efficiency (polishing rate) and polishing life, and such a precision polishing composition An object of the present invention is to provide a method capable of highly precisely polishing a hard and brittle material by using an object.

[0009]

According to the present invention, there is provided a precision polishing composition comprising α-alumina dispersed in an aqueous medium in order to solve such a problem. A precision polishing composition (precision polishing material) for hard and brittle materials, characterized by having fine particles having an average particle diameter (D50) of 0.3 μm or less and a BET specific surface area of 15 to 50 m ² / g. It is an abstract.

As described above, the precision polishing composition for hard and brittle materials according to the present invention has a mean particle diameter (D50) of 0.3 μm or less as a solid component exhibiting polishing characteristics and a BE.
It is characterized by containing α-alumina fine particles having a T specific surface area of 15 to 50 m ² / g and dispersing them in an aqueous medium. In particular, α-alumina fine particles are not coarse particles having a large particle size, and in a fine state, the particles are dispersed in an aqueous medium without settling, so that harmful processing strain is caused. In addition to being able to be effectively avoided, damage to the polished surface such as scratches or deterioration of the surface roughness of the polished surface can be advantageously prevented or eliminated. This made it possible to precisely polish the surface to a highly specular surface. Further, since the α-alumina fine particles having such a configuration are used, a high polishing efficiency (speed), which cannot be achieved by the conventional abrasive, can be advantageously achieved, and the polishing time can be reduced. In addition, the polishing efficiency (speed) can be reliably maintained for a relatively long time in repeated use, that is, a good polishing life can be realized. Thus, a drastic improvement in work efficiency and workability in the precision polishing of hard and brittle materials and realization of excellent economic efficiency can be advantageously achieved.

According to one preferred embodiment of the precision polishing composition according to the present invention, the α-alumina fine particles are dispersed in the composition at a ratio of 5 to 40% by weight.
This allows the above-described effects to be more effectively exerted.

According to the present invention, there is provided a precision polishing composition comprising α-alumina dispersed in an aqueous medium in order to solve the above-mentioned problems. Has an average particle diameter (D50) of 3 μm or less,
And a fine polishing composition for hard and brittle materials, wherein the fine polishing composition comprises fine particles having a BET specific surface area of 15 to 50 m ² / g, and further has silica particles dispersed and contained therein. It is an abstract.

In the precision polishing composition for hard and brittle materials according to the present invention, α-alumina fine particles having the above-mentioned characteristic structure are used as a solid component exhibiting a polishing effect. The combination of the predetermined silica particles with the α-alumina fine particles so that the two components are polished has a particularly remarkable feature. That is, with the α-alumina fine particles having such a configuration, as described above, in the quality of the polished surface, polishing efficiency and maintenance thereof, excellent functions can be exhibited, and by the combination of α-alumina fine particles and silica particles, As a synergistic effect, the surface roughness characteristics and the ability to prevent scratches and other scratches are further improved, and the polishing resistance during polishing is moderately reduced. In addition, the vibration generated during polishing can be advantageously reduced, and higher polishing efficiency can be achieved.

In the precision polishing composition for hard and brittle materials according to the present invention, at least one of colloidal silica, amorphous silicon dioxide and fumed silica is advantageously used as the silica particles. Will be done.

According to one preferred embodiment of the precision polishing composition for hard and brittle materials according to the present invention,
The α-alumina fine particles are dispersed and contained in the composition at a ratio of 5 to 40% by weight, while the silica particles are dispersed and contained in the composition at a ratio of 45% by weight or less. The total content of the α-alumina fine particles and the silica particles is set to 50% by weight or less, whereby the various excellent effects described above are achieved.
It can be played more effectively.

In the precision polishing composition for hard and brittle materials according to the present invention as described above, the pH is 8.5 to 12.
It is desirable to be adjusted to the alkalinity, whereby the electric repulsion acting between the particles effectively acts on each particle, and the solid component is evenly dispersed, so that Aggregation and hardening of these fine particles can advantageously reduce or prevent the occurrence of problems such as a reduction in polishing accuracy and difficulty in repeated use.

According to a preferred embodiment of the precision polishing composition according to the present invention, the α-alumina fine particles include:
It is desirable that the primary particles are obtained by pulverizing a calcined product using boehmite and / or pseudo-boehmite as a raw material, and such α-alumina fine particles can provide a more excellent effect.

Further, according to the present invention, a precision polishing composition or a precision polishing material as described above is used and supplied to the contact surface between the hard and brittle material to be polished and the polishing cloth. The gist of the present invention is a precision polishing method for hard and brittle materials, which is characterized by performing polishing of such hard and brittle materials.

In the method of the present invention, since the precision polishing composition as described above is used, the polished surface of the hard and brittle material can be polished and finished to a high mirror surface. Moreover, due to the effective polishing efficiency and polishing life characteristics of such a precise polishing composition, it is possible to perform precision polishing on hard and brittle materials with excellent work efficiency and workability and good economic efficiency. .

In the method for precisely polishing a hard and brittle material according to the present invention, the hard and brittle material is preferably a lithium tantalate single crystal material or a lithium niobate single crystal material.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the precision polishing composition (precision polishing material) for hard and brittle materials according to the present invention, solid components which are dispersed in an aqueous medium and exhibit an effective polishing action include: The use of the specific α-alumina has a great feature. That is, as is well known, alumina is obtained by calcining aluminum hydroxide and subjecting it to thermal decomposition (dehydration), and its crystal structure becomes γ as the firing temperature increases. Phase, δ phase, θ phase, etc., and finally becomes the most thermally stable α phase (α-alumina) at a temperature of 1000 ° C. or higher. As a result, among such α-alumina, it was found that the one having a predetermined α-formation rate, not being completely α-formed, on the way to it, exhibited an excellent polishing action, The present invention uses α-alumina having such a predetermined ratio of α-alumina.

The α-alumina having such a predetermined ratio of α-alumina generally has the characteristics of fine particles obtained by pulverizing the calcined product, that is, the average particle diameter (D50) and the BET.
In the present invention, as the α-alumina, since it can be indirectly specified by the specific surface area,
Having an average particle diameter (D50) of 0.3 μm or less, and B
Fine particles having an ET specific surface area of 15 to 50 m ² / g were used. When the average particle diameter (D50) of α-alumina exceeds 0.3 μm, scratches such as scratches and pits are formed on the polished surface of the hard and brittle material which is the workpiece to be polished, or the surface roughness of the polished surface is reduced. This is because the degree of roughness is reduced, and the quality of the polished surface is deteriorated, and a problem of causing harmful processing distortion is caused. Also, α-alumina having a BET specific surface area smaller than 15 m ² / g, for example, a BET specific surface area of 10 μm used for polishing the Ni—P surface of a hard disk.
In the case of α-alumina, which is a normal abrasive material of about m ² / g, the quality of the polished surface is deteriorated.
If the BET specific surface area is larger than 50 m ² / g, problems such as a remarkable decrease in polishing efficiency (polishing rate) will be caused.

In the present invention, the α-alumina fine particles have an average particle diameter (D5
0) is 0.3 μm or less.
Preferably, those having a particle diameter of about 0.2 μm or less can be advantageously employed, and the maximum particle diameter (Dmax) of α-alumina fine particles having such an average particle diameter is 1.4 μm.
m or less is desirable. Also, such α-
The particle size of the alumina fine particles is obtained by various measurement methods, but is advantageously obtained from the particle size distribution measured by a laser particle size distribution measuring device using a laser. A highly accurate particle size can be obtained.

The α-alumina fine particles used in the present invention have such a particle diameter and, as described above, have a BET specific surface area of 15 to 50 m ² / m ² .
g, preferably 20 to 40 m ² / g
Is adopted. The BET specific surface area can be measured according to various known methods such as a gas-phase or liquid-phase adsorption method, an immersion heat method, a permeation method, and a reaction rate method.

Further, in the present invention, the specific α-alumina fine particles according to the present invention are generally subjected to a predetermined sintering treatment using aluminum hydroxide as a raw material, and the obtained sinter is subjected to a ball mill or the like. It can be produced by pulverizing, and more preferably, at least one of boehmite and pseudo-boehmite as a raw material, and pulverizing the calcined product to obtain the desired α- Alumina is advantageously obtained as primary particles.

When α-alumina fine particles having such characteristics are obtained, the firing treatment for obtaining a fired product as a precursor thereof depends on the accuracy of the firing furnace to be used. It is desirable to carry out at a firing temperature of ° C. Although α-alumina is obtained by firing at the highest firing temperature among aluminas, its α conversion, the average particle diameter and the BET specific surface area are determined by the firing temperature or the firing degree. Specifically, when the firing temperature is higher than the temperature, the α-rate is increased, crystal growth in the fired product proceeds, and the hardness increases, so that the polishing efficiency is increased. Although (speed) is improved, the calcined product of α-alumina cannot be pulverized into fine particles having an average particle size of 0.3 μm or less. As α-alumina cannot be pulverized into fine particles as in the above, the value of the BET specific surface area is too small, and conversely, if the firing temperature is lower than the above-mentioned temperature, the α conversion is significantly reduced, powder There was progress,
This is because it becomes soft like clay, in other words, the BET specific surface area becomes excessively large.

When the fired product obtained as described above is pulverized with a ball mill or the like to obtain the desired α-alumina fine particles, the pulverization treatment is followed by classification or the like to obtain a particle size. In order to prevent α-alumina fine particles from being removed together with the coarse particles due to agglomeration thereof, various known anions may be used as dispersants. It is preferable to use a surfactant.

In the present invention, by using fine particles of α-alumina having such a characteristic structure and dispersing them in an aqueous medium, precision polishing for the intended hard and brittle material is performed. The composition or the precision polishing material is constituted, whereby the desired polishing characteristics are exhibited.

In short, such a precision polishing composition for hard and brittle materials according to the present invention does not contain α-alumina which is a coarse particle having a large particle size, and α-alumina is finely pulverized. In the state of the fine particles, which are dispersed in an aqueous medium to form a slurry, harmful processing distortion can be effectively avoided, and the quality of the polished surface is advantageously reduced. It is possible to precisely polish the surface of the hard and brittle material to a high mirror surface, and furthermore, by using specific α-alumina fine particles, Polishing efficiency (speed) that could not be achieved can be advantageously achieved,
The time required for polishing can be shortened, and the polishing efficiency (speed) can be reliably maintained for a relatively long time during repeated use, that is, excellent polishing life characteristics can be realized. As a result, it is possible to advantageously improve the work efficiency and workability in precision polishing and reduce the cost as much as possible.

In the precision polishing composition, α
-The content of the alumina fine particles is appropriately set according to the required polishing characteristics and the like, but preferably,
α-alumina fine particles may be used at a ratio of 5 to 40% by weight, more preferably at a ratio of 10 to 30% by weight,
It is desirable to be dispersed and contained in the composition. This is because, when the content of the α-alumina fine particles is too small, although the polishing efficiency or the polishing rate is slightly improved, the above-mentioned effects cannot be sufficiently realized. -When the content of the alumina fine particles is too large, it is not possible to obtain an effect corresponding to the added amount, which is not preferable in terms of economy.

In the precision polishing composition for hard and brittle materials according to the present invention, it is desirable that the pH is adjusted to 8.5 to 12, more preferably to 9.5 to 11 alkaline. . However, when the pH is less than 8.5, particularly in an acidic region, agglomeration of α-alumina fine particles is caused and the α-alumina fine particles are not uniformly dispersed. On the other hand, when the pH is higher than 12, the composition gels and the α-alumina fine particles are not uniformly dispersed, so that the action as a polishing composition (polishing slurry) can be effectively exhibited. Because it is gone.

In addition, in the precision polishing composition according to the present invention, by adjusting the pH to a predetermined value and stabilizing, the solid components are more reliably dispersed, and further polishing is promoted. Further, it is desirable to include a predetermined dispersant. In addition, as such a dispersant,
Various known alkaline agents are used, and specifically, NaOH, KOH, ammonia, organic amines, and one or more of anionic surfactants are appropriately combined and used. Will be done.

Further, in the present invention, by using the fine particles of α-alumina having the above-mentioned characteristic structure and dispersing them in an aqueous medium, and further dispersing and containing silica particles, An effective precision polishing composition (abrasive) for hard and brittle materials will be constituted.

That is, in the precision polishing composition for a hard and brittle material having such a constitution, the quality of the polished surface, the polishing efficiency (speed) and the maintenance thereof in the hard and brittle material can be maintained by the predetermined α-alumina fine particles. In addition to exhibiting excellent functions, by combining α-alumina fine particles and silica particles and performing polishing with these two components, an effective synergistic effect can be exhibited and the surface of the polished surface can be expressed. The prevention of scratches such as roughness and scratches is further improved, and the polishing resistance at the time of polishing is appropriately moderated, so that the polishing efficiency can be maintained more continuously. As a result, vibration generated during polishing can be reduced, and higher polishing efficiency can be achieved.

In the precision polishing composition, as the silica particles dispersed and contained in the aqueous medium, various known silicon dioxides are used. Preferably, colloidal silica and amorphous silica are used. At least one of silicon and fumed silica,
It is advantageously used. In the present invention, as the silica particles, those having a particle diameter of about 0.3 μm or less, which can be dispersed in an aqueous medium in a colloidal form,
Adopted advantageously.

The content ratio of the silica particles in the precision polishing composition for hard and brittle materials according to the present invention is appropriately determined in consideration of required polishing characteristics and the like. Generally, the silica particles are dispersed and contained at a ratio of 45% by weight or less. If the content exceeds 45% by weight, the effective effects that can be achieved by the specific α-alumina fine particles will be impaired. The content of the silica particles in the precision polishing composition is more preferably in the range of 10 to 30% by weight.

Further, the mixing ratio of the specific α-alumina fine particles and the silica particles in the precision polishing composition according to the present invention is desirably set as described above. More preferably, the α-alumina fine particles are more preferable. And the total content of silica particles is 50% by weight or less, more preferably 4% by weight or less.
0% by weight or less. This is because when the total content of the α-alumina fine particles and the silica particles exceeds 50% by weight, the solid component becomes too large and the composition does not form a slurry, so that the polished surface This is because the quality is lowered and the viscosity of the composition is increased, so that it is difficult to obtain stable polishing operation conditions.

The precision polishing composition further containing such silica particles has a pH of 8.5.
It is desirable that the alkalinity is adjusted to be from 12 to 12, more preferably from 9.5 to 11, so that aggregation of the solid component is effectively prevented.

The precision polishing composition (precision polishing material) according to the present invention is to be used for precision polishing of various known hard and brittle materials. It can be advantageously applied to a lithium tantalate single crystal material or a lithium niobate single crystal material, whereby the various excellent effects as described above can be effectively exerted.

In order to subject such a hard and brittle material to precision polishing using the precision polishing composition according to the present invention, for example, as shown in FIG. Will be performed. Here, the precision polishing composition according to the present invention was applied to the polishing slurry 12.
Wafer 1 made of hard and brittle material
The method of forming a polished surface by precision polishing finishing of No. 4 will be described.

In FIG. 1, the polishing machine 10 has been widely used as a polishing machine for wafers in the past, and has a platen 18 mounted on a turntable 16 and The apparatus includes a holder 20 called a substrate holder or a work holder, and a supply device (not shown) connected to the slurry supply nozzle 22.

More specifically, the surface plate 18 has a disk shape, and is concentrically mounted on the turntable 16 which is rotatable around a rotation shaft 24 at a predetermined rotation speed. Is mounted on and fixed to the turntable 16.
A polishing cloth 28 made of polyurethane or the like is attached to the upper surface of the polishing pad.

The holder 20 is provided at a predetermined position above the surface plate 18, while the wafer 14 can be bonded and fixed to the lower surface of the holder 20 at the predetermined position. It has become. A rod 30 is connected to the upper surface of the holder 20. The holder 20 is rotatable around a central axis 32 of the rod 30 at a predetermined rotation speed. In the direction perpendicular to the axis, swing driving can be performed at a predetermined speed. Further, a predetermined pressing force can be applied to the holder 20 via the rod 30 in the axial direction thereof.

Further, the slurry supply nozzle 22 is disposed above the surface plate 18 at a predetermined position, and the slurry 12 supplied to the supply container of the supply device to which the slurry supply nozzle 22 is connected is provided. The slurry is supplied onto the polishing pad 28 from the tip of the slurry supply nozzle 22.
The supply device to which the slurry supply nozzle 22 is connected is provided with a circulation device such as a tube pump, and the polishing slurry 12 is supplied onto the polishing pad 28 at a constant supply speed through the slurry supply nozzle 22. The polishing slurry 12 which is dropped and supplied and overflows from above the polishing cloth 28 is recovered and returned to the supply container of the supply device. That is, in the polishing machine 10, the polishing slurry 12 is used repeatedly.

In order to form a polished surface by subjecting the wafer 14 to precision polishing using the polishing machine 10 having such a configuration, first, the lower surface of the holder 20 is formed by various known bonding methods. The polishing slurry 12 is supplied to a supply container of a supply device while the wafer 14 is adhered and fixed to the substrate. Next, under a state where the wafer 14 and the polishing pad 28 are brought into contact with each other, a predetermined pressing force is applied to the holder 20.
The wafer 14 is moved to the polishing cloth 28
, The holder 20 is driven to rotate and swing, and the turntable 16 is driven to rotate. At the same time, the supply device is operated to drop the polishing slurry 12 from the slurry supply nozzle 22 onto the polishing cloth 28, so that the polishing slurry 12 is supplied to the contact surface between the wafer 14 and the polishing cloth 28. As a result, the wafer 14 is polished to form a polished surface.

Therefore, according to such a precision polishing method, since the precision polishing composition for hard and brittle materials according to the present invention is used, the polished surface of the hard and brittle material (wafer) is polished to an extremely high mirror surface. It is possible to finish. Furthermore, the effective polishing efficiency (speed) of the precision polishing composition makes it possible to easily shorten the polishing time, and even when the precision polishing composition (polishing slurry) is used repeatedly, Since the polishing effect can be maintained continuously due to the good polishing life characteristics, the number of replacements can be reduced as much as possible. ), It is possible to carry out precision polishing on hard and brittle materials with excellent work efficiency and workability and good economic efficiency.

The method for precisely polishing hard and brittle materials using the precision polishing composition according to the present invention is not limited to the illustrated method, but is limited to the required polishing characteristics and the structure of the polishing machine used. May be implemented in various modes.

For example, a precision polishing composition (polishing slurry)
As a supply form, it is desirable to adopt a circulation supply method in which the precision polishing composition is repeatedly used as illustrated, but the precision polishing composition is diluted and used, and without diluting it, it is successively used. Of course, it is also possible to adopt a method of discarding.

[0049] In addition, various types of structures and configurations can be employed in a polishing machine used for performing precision polishing, as long as it can polish a hard and brittle material. It is of course possible to improve the work efficiency by adopting a device having a plurality of holders (20) as described above, whereby the benefits brought by the present invention can be further enjoyed.

[0050]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not construed as being limited by the following Examples. Based on the knowledge of those skilled in the art, the present invention can be implemented in a form in which various changes, modifications, improvements, and the like are made,
It goes without saying that all of these various embodiments are within the scope of the present invention unless they depart from the gist of the present invention.

Preparation of Alumina Abrasive Dispersion Slurry First, pseudo-boehmite was used as a raw material, and it was heated at a firing temperature (about 1120 to 1160 ° C.) higher than the A: θ phase firing region.
B: α obtained by firing at a firing temperature of 1200 ° C. or at a temperature lower than C: firing temperature A, respectively.
Using fired alumina and adding 50 parts by weight of water to 50 parts by weight of each of the fired products,
It is pulverized by a ball mill for 90 hours.
Alumina was dispersed so as to be contained in a proportion of 30% by weight, and wet classification was performed to prepare a dispersed slurry of alumina abrasive grains (α-alumina concentration: 30% by weight). Then, after sampling a predetermined amount of the obtained alumina abrasive grain dispersion slurry, respectively, a specific surface area measuring instrument (Flosorb II2300 manufactured by Shimadzu Corporation)
While measuring the sampled BET specific surface area using a laser particle size distribution analyzer (Shimadzu Corporation: S
ALD2000) was used to measure the respective particle size distributions, and the average particle size (D50) was determined therefrom.

Preparation Example 1 of Abrasives Of the alumina abrasive grain dispersion slurry obtained by pulverizing and classifying the α-alumina fired product at the firing temperature A as described above, the BET specific surface area and After using a material having an average particle diameter (α-alumina concentration: 30% by weight), adding 333 g of water and adjusting the concentration, a 5% aqueous solution of NaOH is further added dropwise with stirring. Then, the pH was adjusted to 10.5 to obtain 1 kg of an abrasive in which α-alumina was blended at a ratio of 10% by weight.

Example 2 Of the dispersion slurry of alumina abrasive grains obtained from the fired product at the firing temperature A, one having a BET specific surface area and an average particle diameter shown in Table 1 below was used, and water was added to 333 g of the slurry. A 5% aqueous solution of NaOH was added dropwise with stirring, and a slurry having a pH of 10.0 was prepared. A slurry of a commercially available alkaline colloidal silica (average particle diameter of silica: 80 nm, solid component concentration) was added thereto. : 40% by weight, pH:
10) was added and stirred to obtain α
10% by weight and 2% alumina and silica, respectively
Abrasive (1k
g) was obtained.

Examples 3 to 6 In the same manner as in Examples 1 and 2, of the alumina abrasive grain dispersion slurry obtained from the α-alumina fired product at the firing temperature A,
Those having the BET specific surface area and the average particle diameter shown in Table 1 below were used, and each of them had 5% of water and NaOH.
The aqueous solution was added, and the commercially available colloidal silica liquid used in Example 2 was added and mixed (however, in Example 3, not added), and the mixing ratio of the solid component and p
H was used to prepare abrasives (Examples 3 to 6) as shown in Table 1 below.

Example 7 Among the alumina abrasive grain dispersion slurries obtained from the calcination product at the calcination temperature A, the BET specific surface area and the average particle diameter were as shown in Table 1 below.
Was added to 500 g of the mixture, and a 5% aqueous solution of NaOH was added dropwise with further stirring.
A slurry (615 g) in which H was adjusted to 11.0 was obtained. Next, 10 g of commercially available amorphous silicon dioxide (Carplex CS-5, primary particle diameter: 20 nm) was added to the slurry.
Was added, and 375 g of the same colloidal silica liquid as used in Example 2 was added and stirred to prepare an abrasive having a solid component blending ratio and pH values shown in Table 1 below. .

Example 8 Using the alumina abrasive grain dispersion slurry used in Example 1 above, water was added to 500 g of the slurry, the concentration was adjusted, and a 5% aqueous solution of NaOH was added dropwise with stirring. 625 g of a slurry with a pH of 10.5 were obtained. Next, 375 g of the same commercially available colloidal silica liquid as described above was added to the slurry and stirred, whereby both α-alumina and silica were contained at a ratio of 15% by weight and the pH was 10%. 0.3 abrasive (1 kg) was obtained.

Comparative Examples 1 and 2 First, as Comparative Example 1, α of the firing temperature B was determined as described above.
-A slurry of alumina abrasive grains obtained by pulverizing and classifying the alumina fired product (BET specific surface area: 12.5 m ² /
g, average particle diameter: 0.34 μm, α-alumina concentration: 3
0% by weight), water was added to 333 g of the solution to adjust the concentration, and then, while stirring, a 5% aqueous solution of NaOH was added dropwise to contain α-alumina at a rate of 10% by weight and pH. Of 10.5 was prepared. As Comparative Example 2, the same alumina abrasive grain dispersion slurry as used in Comparative Example 1 was used.
Water was added to 0 g, and then NaOH (5% aqueous solution) was added dropwise with stirring so that the pH became 11.0, to prepare 625 g of a slurry.
The same colloidal silica liquid as used in Example 2 was applied to 37
By adding 5 g and stirring, an abrasive having a blending ratio of solid components and a pH as shown in Table 1 below was obtained.

Comparative Examples 3 and 4 As Comparative Example 3, in the preparation of the above-mentioned slurry for dispersing alumina abrasive grains, a slurry for dispersing alumina abrasive grains (BET specific surface area: 6
(1.7 m ² / g, average particle diameter: 0.19 μm, α-alumina concentration: 30% by weight), water was added to 833 g, and then NaOH was adjusted to pH 10.7.
5% aqueous solution was added dropwise with stirring, and an abrasive (1) containing α-alumina in a ratio of 25% by weight was added.
kg) was prepared. Further, as Comparative Example 4, the same alumina abrasive grain dispersion slurry as that used in Comparative Example 3 was used, and water was added to 500 g of the slurry, and Na was added with further stirring.
OH (5% aqueous solution) was added dropwise to adjust the pH to 1
After adjusting to 1.0, 375 g of the colloidal silica liquid used in Example 2 was added thereto, and the mixture was stirred, whereby the mixing ratio of the solid component and the pH were set to the values shown in Table 1 below (1 kg). I got

Comparative Example 5 A commercially available alkaline colloidal silica liquid (average of silica) as described above, which is mainly used for polishing silicon wafers and has also been used as an abrasive for lithium tantalate single crystal material. Particle size: 80 nm, solid component concentration: 40% by weight) was used as an abrasive.

Polishing test Of the abrasives obtained above, 1 kg of the abrasives according to Examples 1 to 7 and Comparative Examples 1 to 5 were respectively polished with a polishing machine (SLM-100, manufactured by Fujikoshi Co., Ltd., polishing platen). Diameter: 3
50 mm), the surface of a wafer (diameter: 75 mm) made of a lithium tantalate single crystal material was polished (precisely polished) for 5 hours using the polishing machine. In this polishing, the rotation speed (rotation speed) of the platen was set to 60 rpm, and the polishing pressure was 200 g / cm ² . In addition, the abrasive material is 200
The slurry was supplied at a supply rate of mL / min onto the surface of the polishing cloth stuck on the platen, and the overflowing abrasive was returned to the container.

Then, while polishing the surface of the wafer as described above, every one hour of the polishing time,
The thickness of the wafer was measured using a micrometer (manufactured by Sanyo, measurement accuracy: 1 μm), and the polishing rate (μm / h) per hour was determined from the thickness. The results are shown in Table 2 below. One hour after the start of polishing, a stereoscopic microscope (manufactured by Leica: Microscope M420) was used.
The polished surface of the wafer was observed at a magnification of 40 times, and the surface condition of the polished surface at the initial stage of polishing was evaluated based on the presence or absence of scratches or pits. The evaluation results are shown in Table 3 below.

[0062]

[Table 1] * 1: Total of the mixing ratio of amorphous silicon dioxide and colloidal silica

[0063]

[Table 2]

[0064]

[Table 3]

As is clear from the results of Tables 2 and 3,
In the abrasives of Examples 1 to 7 according to the present invention, it was recognized that the polishing rate was high, and that the reduction in the polishing rate over time was small, and that the polishing surface of the wafer had scratches from the beginning of polishing. And the occurrence of pits can not be observed at all,
Recognized that it is a high quality surface.

On the other hand, in the abrasives of Comparative Examples 1 and 2,
At the beginning of polishing, scratches and pits were observed on the polished surface. In the polishing material of Comparative Example 3, it was recognized that a large number of fine pits were generated on the surface of the polished surface in the initial stage of polishing, and a sufficient polishing rate was obtained except in the initial stage of polishing. It can be seen that no polishing material was obtained, and that the polishing rate of the polishing material of Comparative Example 4 was not sufficient. Furthermore, in the polishing material of Comparative Example 5 as a conventional example, although the quality of the polished surface was good, it was recognized that the polishing rate or the polishing efficiency was not sufficient. ) Until 3 hours, an average polishing rate of 4.3 μm / h is maintained, but it is recognized that if polishing is further continued, the polishing rate is significantly reduced.

Polishing Life Test Using the abrasive obtained in Example 8, the surface of a wafer (diameter: 75 mm) made of a single crystal lithium tantalate material was polished for 10 hours in the same manner as in the above polishing test. (Precision polishing) Each time the polishing time elapses for one hour, a micrometer (manufactured by Mitoyo, measurement accuracy: 1μ)
Measure the thickness of the wafer using
The polishing rate per hour (μm / h) was determined. The results are shown in Table 4 below.

[0068]

[Table 4]

As is clear from the results shown in Table 4 above, in the abrasive of Example 8 according to the present invention, the effective polishing rate (polishing effect) is maintained substantially constant over a long period of time. This means that the polishing life is excellent.

[0070]

As is clear from the above description, in the precision polishing composition for hard and brittle materials according to the present invention, specific α-alumina fine particles are dispersed in an aqueous medium. Therefore, harmful processing distortion can be effectively avoided, and the deterioration of the quality of the polished surface can be advantageously prevented or eliminated, so that This made it possible to precisely polish the surface of hard and brittle materials to a high-level mirror surface. Furthermore, the polishing efficiency (speed) that could not be achieved conventionally can be advantageously achieved, and the time spent for polishing can be shortened. In addition, when the polishing is repeatedly used, the polishing efficiency or the polishing speed is reduced. It can be reliably held for a relatively long time, that is, a good polishing life characteristic can be realized.

According to the method for precisely polishing hard and brittle materials using the precision polishing composition according to the present invention, the polished surface of the hard and brittle material can be polished to a high-level mirror surface, and the precision polishing composition can be exhibited. Due to the effective polishing efficiency and polishing life characteristics, it is possible to perform precision polishing on hard and brittle materials with excellent work efficiency and workability and good economic efficiency.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing a state in which a hard and brittle material is subjected to precision polishing using the precision polishing composition for a hard and brittle material according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Polishing machine 12 Polishing slurry 14 Wafer 16 Turntable 18 Surface plate 20 Holder 22 Slurry supply nozzle 28 Polishing cloth

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01L 21/304 622 H01L 21/304 622D (72) Inventor Yoshiki Hayashi 153 Mt. F-term (reference) in Kuchiseiken Kogyo Co., Ltd. 4G076 AA02 AA24 AC04 BC08 BD01 CA02 CA15 CA26 CA28 DA30 FA02 4G077 AA03 BC37 FG12

Claims (11)

[Claims] 1. A precision polishing composition comprising α-alumina dispersed in an aqueous medium, wherein the α-alumina has an average particle diameter (D50) of 0.3 μm or less and a BET specific surface area. Consists of fine particles having a particle size of 15 to 50 m ² / g. 2. The precision polishing composition for hard and brittle materials according to claim 1, wherein the α-alumina fine particles are dispersed and contained in the composition at a ratio of 5 to 40% by weight. 3. The precision polishing composition for hard and brittle materials according to claim 1, wherein the pH is adjusted to an alkaline value of 8.5 to 12. 4. The hard brittle material according to claim 1, wherein the α-alumina fine particles are primary particles obtained by pulverizing a calcined product using boehmite and / or pseudo-boehmite as a raw material. Precision polishing composition for materials. 5. A precision polishing composition comprising α-alumina dispersed in an aqueous medium, wherein the α-alumina has an average particle diameter (D50) of 0.3 μm or less and a BET specific surface area. Is a fine polishing composition for hard and brittle materials, comprising fine particles of 15 to 50 m ² / g, and further comprising silica particles dispersed and contained therein. 6. The precision polishing composition for hard and brittle materials according to claim 5, wherein at least one of colloidal silica, amorphous silicon dioxide and fumed silica is used as said silica particles. 7. The fine particles of α-alumina are dispersed and contained in the composition at a ratio of 5 to 40% by weight, while the silica particles are dispersed and contained in the composition at a ratio of 45% by weight or less. 7. The precision polishing composition for hard and brittle materials according to claim 5, wherein the total content of the α-alumina fine particles and the silica particles is 50% by weight or less. 8. The precision polishing composition for hard and brittle materials according to claim 5, wherein the pH is adjusted to an alkaline value of 8.5 to 12. 9. The hard brittle material according to claim 5, wherein the α-alumina fine particles are primary particles obtained by pulverizing a calcined product using boehmite and / or pseudo-boehmite as a raw material. Precision polishing composition for materials. 10. Using the precision polishing composition according to any one of claims 1 to 9, supplying it to a contact surface between a hard brittle material to be polished and a polishing cloth, A method for precisely polishing hard and brittle materials, which comprises polishing such hard and brittle materials. 11. The method according to claim 10, wherein the hard brittle material is a lithium tantalate single crystal material or a lithium niobate single crystal material.