JP2002220584A - Precision abrasive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a precision abrasive capable of providing a high polishing speed. SOLUTION: This precision abrasive comprises aluminosilicate powder. The precision abrasive comprises >=50 mass% calculated as SiO2 and Al2O3 of the total of Si and Al in the molar ratio of Si to Al of 0.01<Si/Al<=100 in the aluminosilicate powder. The precision abrasive has 50-100 mass% aluminosilicate content described in either of the above-mentioned precision abrasives. The precision abrasive has 3-150 m2/g BET specific surface area, (D90-D10)/D50<50 when particle diameters of accumulation 10%, accumulation 50% and accumulation 90% from fine particle side of accumulation particle size distribution measured by laser diffraction scattering method are D10, D50 and D90, respectively and <=5 μm D50 described in any of the above-mentioned precision abrasive. The precision abrasive has 2.0-4.0 g/cm3 density of particles of the aluminosilicate powder described in any of the above-mentioned precision abrasive. This slurry for precision polishing is obtained by using the described precision abrasive in any of the above-mentioned precision abrasives.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a precision abrasive. In particular, it relates to a precision abrasive used for polishing various semiconductors, photomasks, hard disk substrates, and the like.

[0002]

2. Description of the Related Art Precision abrasives are used for semiconductor substrates (wafers),
It is used for polishing photomasks, hard disk substrates and the like.

[0003] For example, a hard disk substrate is generally prepared by subjecting an aluminum surface to a base treatment and attaching Ni-P by chemical plating. A precision polishing material for this substrate is mainly composed of alumina. Certain powders are widely used. In recent years, glass substrates have also become widespread as hard disk substrates in order to cope with miniaturization and high capacity, and powders such as cerium oxide, zirconium oxide, and silica are used as precision abrasives for these substrates. ing.

In order to flatten the surface of a photomask used in optical lithography or to flatten the surface of an interlayer insulating film in the manufacture of a multilayered integrated circuit, mechanochemical polishing (Chemic polishing) combining mechanical polishing and chemical polishing is used.
al Mechanical Polishing, hereinafter referred to as “CMP”. ), And a powder such as alumina or silica is used as the precision abrasive for CMP.

In any of the above applications, a high polishing rate is required, and as a precision polishing material, silica (S
iO ₂ ), alumina (Al ₂ O ₃ ), ceria (CeO ₂ ),
Metal oxide powders such as zirconia (ZrO ₂ ) and titania (TiO ₂ ) have been used, but the polishing rate was not sufficient.

[0006] For example, Japanese Patent Application Laid-Open No. 2000-160139 discloses that a slurry prepared by using fine silica or alumina powder as a precision abrasive and dispersing the precision abrasive in water contains hydrogen peroxide and oxalic acid. Although a tantalum polishing slurry added is disclosed, the tantalum polishing rate was not sufficient.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a precision abrasive which can obtain a high polishing rate.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, when aluminosilicate powder is used as a precision abrasive, a conventional precision abrasive is used. It has been found that the polishing rate is higher than in the case where the present invention has been performed, and the present invention has been completed.

That is, the present invention provides a precision abrasive containing an aluminosilicate powder. Further, the present invention provides a method for producing aluminosilicate powder in which the content of Si and Al is
O ₂ and Al ₂ O ₃ , the total content is 50% by mass or more, and Si
And the molar ratio of Al to Al is 0.01 <Si / Al <100. Further, the present invention provides the precision abrasive according to any one of the above, wherein the content of the aluminosilicate powder is 50 to 100% by mass. Further, the present invention has a BET specific surface area of 3 to 150 m ² / g,
When the particle diameters of 10%, 50% and 90% from the fine particle side of the cumulative particle size distribution measured by the laser diffraction scattering method are D10, D50 and D90, respectively, (D90−
D10) / D50 is 5 or less, and D50 is 5 μm or less. Further, the present invention provides the precision abrasive according to any one of the above, wherein the density of the particles of the aluminosilicate powder is in the range of 2.0 to 4.0 g / cm ³ . Further, the present invention provides a slurry for precision polishing using any of the precision abrasives described above.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. Aluminosilicate used as a precision abrasive in the present invention (aluminosilicate) is a salt produced part of the silicon silicate is replaced by aluminum, the general formula ^{_{x I M I 2 O · x}} II M II O ・ yAl ₂ O ₃・ zSiO ₂・ n
H ₂ O (where x _I , x _II , n is a number greater than 0, y, z
Is a number greater than 0, M ^I is Li ⁺ , Na ⁺ , K ⁺ , Tl ⁺
For example, M ^II is Ca ²⁺ , Mg ²⁺ , Ba ²⁺ , Sr ²⁺ . ). Aluminosilicates include clay minerals such as feldspar group minerals, mica group minerals, kaolinite and pyroferrite, minerals composed of SiO ₂ and Al ₂ O ₃ such as sillimanite, kyanite, andalusite, and mullite, mordenite, fauja Naturally occurring substances such as zeolite group minerals such as sites and those synthesized by methods such as the smoke method, sol-gel method, and hydrothermal method such as ZSM-5 and A-type zeolite are included.

The present inventors have found that the polishing rate is increased when aluminosilicate powder is used instead of using a conventionally used substance powder as a precision abrasive. When hard alumina powder is used for precision abrasives,
The polishing rate is higher than when relatively soft silica powder is used for the precision abrasive. When aluminosilicate powder is used as a precision abrasive, the hardness of aluminosilicate is lower than that of alumina, but unexpectedly, a higher polishing rate can be obtained than when alumina is used.

The aluminosilicate powder used in the present invention preferably has a total content of Si and Al of at least 50% by mass in terms of SiO ₂ and Al ₂ O ₃ . The range of the molar ratio of Si to Al is preferably 0.01 <Si / Al <100, more preferably 0.1 <Si / Al <10, and still more preferably 0.2 <Si / Al <5. The content of the aluminosilicate powder in the precision abrasive is preferably 50 to 100% by mass. When the content of Si and Al in the aluminosilicate powder is as small as less than 50% by mass in total in terms of SiO ₂ and Al ₂ O ₃ , when the value of Si / Al is 0.01 or less or 100 or more, precision polishing If the content of aluminosilicate in the material is as low as less than 50% by mass, a high polishing rate may not be obtained.

The BET specific surface area of the aluminosilicate powder used as the precision abrasive of the present invention is 3 to 150 m ^2.
/ G is preferable, and more preferably 5 to 50 m ² / g.
g, more preferably 6 to 30 m ² / g. BET
When the specific surface area is less than 3 m ² / g, a high polishing rate can be obtained. However, when the aluminosilicate powder is dispersed in a dispersion medium such as water to obtain a slurry for precision polishing, the stability of the slurry may be reduced. Not preferred. If the BET specific surface area is larger than 150 m ² / g, a high polishing rate may not be obtained, which is not preferable.

The particle size distribution of the aluminosilicate powder used as the precision abrasive of the present invention is 10% cumulative from the fine particle side of the cumulative particle size distribution measured by the laser diffraction scattering method.
The particle diameters of 50% cumulative and 90% cumulative were determined as D10 and D5, respectively.
0 and D90, (D90-D10) / D50 is preferably as narrow as 5 or less, more preferably 3 or less,
More preferably, it is 2 or less. (D90-D10) /
When D50 is larger than 5, a high polishing rate may not be obtained, which is not preferable. As for the particle diameter, D50 is preferably 5 μm or less, more preferably 2 μm or less, and still more preferably 1 μm or less. When D50 is larger than 5 μm, the stability of the slurry for precision polishing may be reduced, which is not preferable. In addition, D50 which can be measured by a laser diffraction scattering method
Is 0.05 μm or more.

If the particle size of the aluminosilicate powder used as the precision abrasive of the present invention is too large or the BET specific surface area is too small, it can be pulverized if necessary, and the BET critical area, (D90 −D10) / D
50 and D50 can be within the above preferred ranges. Examples of the method of pulverizing the aluminosilicate powder include, for example, a pulverizing method using a vibration mill, a ball mill, a jet mill, an attrition mill, or the like, which is usually used industrially. In ball mill pulverization, any of dry pulverization, wet pulverization or a combination thereof can be used.

The specific gravity of the aluminosilicate powder used as the precision abrasive of the present invention is 2.0 to 4.0 g / cm ^3.
Is preferred. If the specific gravity is less than 2.0 g / cm ³ , a high polishing rate may not be obtained. The specific gravity is 4.
If it is more than 0 g / cm ³ , particles tend to settle when used as a slurry for precision polishing, the stability of the slurry is reduced, and a high polishing rate may not be obtained.

The precision abrasive of the present invention can be used for a slurry for precision polishing. Examples of the dispersion medium in the case of forming a slurry include water, alcohol, and a mixed solvent of water and alcohol, and water is preferred from the viewpoint of waste liquid treatment.

Examples of the method for slurrying the precision abrasive of the present invention include stirring, ultrasonic dispersion, nanomizer dispersion, and a wet ball mill. When the slurry is formed, a dispersant such as sodium hexametaphosphate or ammonium polycarboxylate can be used as needed.

When the precision abrasive of the present invention is used as a slurry, the content of the aluminosilicate powder in the slurry for precision polishing is preferably from 0.1 to 50% by mass, more preferably from 1 to 50% by mass, based on the total amount of the abrasive. 25% by mass. If the content of the aluminosilicate powder is less than 0.1% by mass, the polishing rate may be reduced. If it exceeds 50% by mass, the polishing rate increases, but the dispersion of particles may be difficult. If it becomes difficult to disperse the particles, sedimentation of the aluminosilicate powder in the slurry easily occurs, and the polishing rate of the slurry for precision polishing may be reduced. As an additive of the slurry for precision polishing using the precision polishing material of the present invention, an oxidizing agent or a reducing agent that causes a chemical reaction with the object to be polished is used. Examples of the oxidizing agent include hydrogen peroxide, iron nitrate, iron sulfate, ammonium sulfate, cerium sulfate, cerium ammonium sulfate, citric acid, succinic acid, malonic acid, malic acid, acetic acid, butyric acid, valeric acid, and lactic acid. However, in the present invention, hydrogen peroxide is preferred. Since hydrogen peroxide does not contain metal ions, it has a low risk of contaminating a semiconductor device, and has a strong oxidizing power. On the other hand, examples of the reducing agent include formic acid, oxalic acid, and formaldehyde.

The content of the additive in the slurry for precision polishing of the present invention is preferably 0.002 to 1 mol / L. When the content of the additive is less than 0.002 mol / L, the polishing rate may decrease. When the content is more than 1 mol / L, the polishing rate increases, but the control of polishing becomes difficult, and recess and dishing are caused. Or surface defects such as erosion.

[0021]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The cumulative particle size distribution in the present invention, BE
The measurement of the T specific surface area and the density was performed as follows. 1. Particle size distribution The particle size distribution was measured using a SALD-2000A model manufactured by Shimadzu Corporation, which is a particle size distribution measuring apparatus based on a laser diffraction scattering method. 2. BET specific surface area The BET specific surface area was measured using a flowsorb II2300 type BET specific surface area measuring device manufactured by Shimadzu Corporation. 3. Density The density was measured using an ultra pycnometer 1000, a true density measuring device manufactured by Yuasa Ionics.

Example 1 Aluminosilicate powder AMT-80L (trade name, manufactured by Mizusawa Chemical Industry Co., Ltd., SiO ₂ and Al ₂ O occupying the mass of the powder)
The sum of the masses of ₃ was 89.11%, Si / Al = 0.97,
BET specific surface area 17.8 m ² / g, density 2.4 g / c
Water containing 0.3 g of SN Dispersant 5468 (trade name, polyammonium polycarboxylate manufactured by San Nopco Ltd.) was added to 20 g of m ³ ), and the total amount was adjusted to 200 g. After the ultrasonic dispersion, the dispersion was performed with a Nanomizer, and further, a wet ball mill pulverization was performed. Hydrogen peroxide was added to this slurry to finally prepare a precision polishing slurry having a concentration of 2.5% by mass of the aluminosilicate powder and a concentration of 7.5% by mass of hydrogen peroxide. Using the above slurry, a wafer with a tantalum film formed by sputtering is polished with a polishing machine (MECAPOL E-460, manufactured by PRESI).
Polished. The polishing conditions were as follows.
m, rotation speed of wafer holder 60 rpm, polishing pressure 20
0 g / cm ² , the slurry flow rate was 100 ml / min, and the polishing time was 60 seconds. The test results are shown in Table 1.

Comparative Example 1 α-alumina AA-05 (trade name, Sumitomo Chemical Co., Ltd.)
Made, density 4.0g / cm ^Three)) SN powder on 20g of powder
Water containing 0.3 g of Pazant 5468 was added, and
Was adjusted to 200 g. After ultrasonic dispersion,
Scattered. Add hydrogen peroxide to this slurry and add
Abrasive grain concentration 2.5% by mass, hydrogen peroxide concentration 7.5%
% Slurry was prepared. Using the obtained slurry,
The same wafer as in Example 1 was polished under the same conditions as in Example 1.
Was. The results are shown in Table 1.

Comparative Example 2 γ-alumina AKP-G005 (trade name, Sumitomo Chemical Co., Ltd.)
Water containing 0.3 g of SN Dispersant 5468 was added to 20 g of a powder having a density of 3.5 g / cm ³ manufactured by Co., Ltd.
The total amount was adjusted to 200 g. After the ultrasonic dispersion, the dispersion was performed with a Nanomizer, and further, a wet ball mill pulverization was performed. Hydrogen peroxide was added to the slurry to finally prepare a slurry having an abrasive concentration of 2.5% by mass and a hydrogen peroxide concentration of 7.5% by mass. Using the obtained slurry, a wafer similar to that in Example 1 was polished under the same conditions as in Example 1. The results are shown in Table 1.

Comparative Example 3 γ-alumina UA-5205 (trade name, Showa Denko KK)
Water containing 0.3 g of SN Dispersant 5468 was added to 20 g of the powder having a density of 3.8 g / cm ³ ), and the total amount was 2 g.
It was adjusted to 00 g. After the ultrasonic dispersion, nanomizer dispersion was performed. Hydrogen peroxide was added to the slurry to finally prepare a slurry having an abrasive concentration of 2.5% by mass and a hydrogen peroxide concentration of 7.5% by mass. Using the obtained slurry, a wafer similar to that in Example 1 was polished under the same conditions as in Example 1.
The results are shown in Table 1.

Comparative Example 4 Water containing 0.3 g of SN Dispersant 5468 was added to 20 g of silica P-527 (trade name, Mizusawa Chemical Industry Co., Ltd., density 2.1 g / cm ³ ), and the total amount was 200.
g. After the ultrasonic dispersion, the dispersion was performed with a Nanomizer, and further, a wet ball mill pulverization was performed. Hydrogen peroxide was added to the slurry to finally prepare a slurry having an abrasive concentration of 2.5% by mass and a hydrogen peroxide concentration of 7.5% by mass. Using the obtained slurry, a wafer similar to that in Example 1 was polished under the same conditions as in Example 1. The results are shown in Table 1. From the results shown in Table 1, it can be seen that when alumina silicate was used for the abrasive grains, a higher polishing rate was obtained as compared with silica and alumina.

Example 2 Using a precision polishing slurry prepared in the same manner as in Example 1, a wafer provided with a Si oxide film was polished with a polishing machine (PRES).
ICAP, MECAPOL E-460).
The polishing conditions were as follows: the rotation speed of the polishing platen was 60 rpm, the rotation speed of the wafer holder was 60 rpm, the polishing pressure was 200 g / cm ² ,
The slurry flow rate was 100 ml / min, and the polishing time was 60 seconds. The test results are shown in Table 2.

Comparative Example 5 The same wafer as in Example 2 was prepared by using the same slurry as in Example 2 except that the slurry prepared in Comparative Example 1 was further subjected to a wet ball mill. Polished. The test results are shown in Table 2.

Comparative Example 6 The same wafer as in Example 2 was polished under the same conditions as in Example 2 using the slurry prepared in the same manner as in Comparative Example 3.
The test results are shown in Table 2.

Comparative Example 7 The same wafer as in Example 2 was polished under the same conditions as in Example 2 using the slurry prepared in the same manner as in Comparative Example 4.
The test results are shown in Table 2. From the results shown in Table 2, it can be seen that when alumina silicate was used for the abrasive grains, a higher polishing rate was obtained as compared with silica and alumina.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

The precision abrasive using the aluminosilicate powder of the present invention has a high polishing rate, especially in the precision polishing of tantalum, and has excellent slurry stability when slurried. Therefore, it is industrially useful.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kunio Saegusa 6 Kitahara, Tsukuba, Ibaraki F-term (reference) in Sumitomo Chemical Co., Ltd. 3C058 CA01 CB03 CB10 DA02 DA17

Claims (6)

[Claims] 1. A precision abrasive containing an aluminosilicate powder. 2. The method according to claim 1, wherein the aluminosilicate powder contains Si, A
l content is at least 50% by mass in terms of SiO ₂ and Al ₂ O ₃ , and the molar ratio of Si to Al is 0.01 <Si / Al
2. The precision abrasive according to claim 1, wherein <100. 3. The content of the aluminosilicate powder is 50 to 50.
The precision abrasive according to claim 1 or 2, which is 100% by mass. 4. The aluminosilicate powder has a BET specific surface area of 3 to 150 m ² / g, and has a particle size of 10%, 50% and 90% from the fine particle side of the cumulative particle size distribution measured by a laser diffraction scattering method. To D10, D50,
The precision abrasive according to any one of claims 1 to 3, wherein D90 is (D90-D10) / D50 is 5 or less and D50 is 5 m or less. 5. The precision abrasive according to claim 2, wherein the density of the particles of the aluminosilicate powder is in the range of 2.0 to 4.0 g / cm ³ . 6. A slurry for precision polishing using the precision abrasive according to claim 1.