JPH08319111A - Preparation of colloidal silica-containing abrasion solution - Google Patents

Abstract

PURPOSE: To prevent occurrence of an abrasion mark and deterioration of an abraded face by adding glycerol to a colloidal silica-containing abrasion solution and to reduce retention of the colloidal silica to a tool to be brought into contact with the abrasion solution by adding glycerol to the abrasion solution. CONSTITUTION: An abrasion solution containing colloidal silica, having pH3 to pH11 is mixed with 5-40wt.%, based on the content of the colloidal silica, of glycerol. Consequently, flocculation of the colloidal silica and variability of particle diameters can be prevented even in abrasion in the atmosphere to improve accuracy of an abraded face and to prevent occurrence of an abrasion mark.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a polishing liquid containing colloidal silica used for polishing silicon, quartz glass, multi-component glass, metals, crystals and the like.

[0002]

2. Description of the Related Art Since colloidal silica is unstable in the atmosphere, the colloidal silica-containing polishing liquid is put in a sealed container and is commercially available in a state of being shielded from the atmosphere. There are the following problems in using the above polishing liquid in the atmosphere. (1) Agglomeration of colloidal silica and variation in particle size cause polishing scratches and deterioration of polishing surface accuracy. (2) Agglomerated colloidal silica adheres to equipment such as a polishing machine, a polishing carrier, a polishing pad, and other accessory equipment of a polishing device that comes into contact with a polishing liquid containing colloidal silica during polishing, and it is difficult to remove. .

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, prevents the occurrence of polishing scratches and the deterioration of the accuracy of the polishing surface, and provides colloidal silica for an instrument that comes into contact with a polishing liquid. An object of the present invention is to provide a method for preparing a polishing liquid containing colloidal silica that can reduce sticking.

[0004]

As a method for producing colloidal silica, JP-A-63-74911 discloses a method of hydrolyzing an alkoxysilane in a water-alcohol mixed solution containing an alkaline catalyst. There is. The hydrolysis mechanism of this method is from oligomer to polymer,
From the polymer to the ultrafine particles, the degree of condensation increases and the silica particles become large. At this time, the inventors of the present invention paid attention to the fact that ROH is involved in the growth of the silica particles as shown in the following formula 1, and the earnest test As a result of repeated research, the present invention has been accomplished.

[0005]

(Equation 1)

A method of preparing a colloidal silica-containing polishing liquid according to the present invention for achieving the above object is characterized by adding glycerin to the colloidal silica-containing polishing liquid. In the present invention, when the pH of the colloidal silica-containing polishing liquid is in the range of 3 to 11, the amount of glycerin added is preferably 5 to 40% by weight of the colloidal silica content in the polishing liquid.

[0007]

By adding glycerin to the polishing liquid containing colloidal silica, it is possible to prevent aggregation of colloidal silica and particle size variation. It is considered that this is because the glycerin that has absorbed water surrounds the silica particles, so that the silica particles are not exposed to the atmosphere.

[0008]

EXAMPLES As an example of the method for preparing a polishing liquid containing colloidal silica according to the present invention, a polishing liquid containing colloidal silica manufactured by Fujimi Incorporated (trade name: C
OMPOL80, 40% by weight of colloidal silica, p
H = 10.0), purified glycerin (trade name; glycerin D) manufactured by Lion Corp. to colloidal silica,
Quartz glass substrate for photomasks (5 inch square) that has been polished with cerium oxide using a polishing liquid with 27% by weight added
Was polished in the air for 10 minutes by a double-sided polishing machine, 10 samples were sampled, and the mean square roughness of the substrate surface was measured by a phase difference interference surface roughness meter (model name: WYKO-TOPO-2D). RMS), surface roughness (Ra) and maximum height (PV) were measured, and the state of the substrate surface was visually observed with a light source of 500,000 lux. For reference, ten quartz glass substrates for photomasks polished with cerium oxide were sampled and the same measurement and observation were performed. Further, as a comparative example, using the above colloidal silica-containing polishing liquid to which glycerin is not added, for a photomask quartz glass substrate that has been polished with cerium oxide,
After performing the same polishing as above, 10 samples were sampled,
The same measurement and observation as above were performed. The above measurement and observation results are shown in Table 1 below.

[0009]

[Table 1]

As can be seen from Table 1, the quartz glass substrate polishing product polished by using the colloidal silica-containing polishing liquid prepared by adding and adjusting glycerin according to the examples of the present invention is a colloidal silica-containing polishing product without adding glycerin. The RMS, Ra, and PV measurement values are all lower than those of a polished quartz glass substrate polished with a liquid, and the precision of the polished surface is improved. Also,
As a result of observing the surface state, no surface defects such as scratches were found on the surface of the quartz glass substrate polished product polished with a polishing liquid containing colloidal silica containing glycerin. On the other hand, minute scratches were generated on the surface of a polished quartz glass substrate product polished with a polishing liquid containing no glycerin. Further, in the case of using a polishing liquid without addition of glycerin, the agglomerated colloidal silica is fixed to the equipment such as a polishing machine, a polishing carrier, a polishing pad, and other accessory equipment of the polishing apparatus, and after polishing, this is removed. It wasn't easy. On the other hand, in the example in which the polishing liquid containing glycerin was used, colloidal silica was slightly attached to the above-mentioned devices and equipment, but pure water was 1% by volume.
On the other hand, by washing with a pure water-glycerin mixed solution in which glycerin was appropriately added in the range of 0.5 to 5, the adhered colloidal silica could be easily removed.

[0011]

As described above, since the method for preparing a colloidal silica-containing polishing liquid of the present invention is characterized by adding glycerin to the colloidal silica-containing polishing liquid, polishing is performed in the atmosphere. Also, it is possible to prevent aggregation of colloidal silica and fluctuation of particle diameter, improve accuracy of the polished surface, and prevent occurrence of polishing scratches.
Further, it is possible to reduce sticking of colloidal silica to various devices and instruments that come into contact with the polishing liquid during the polishing process.

Claims (2)

[Claims] 1. A method for preparing a polishing liquid containing colloidal silica, which comprises adding glycerin to the polishing liquid containing colloidal silica. 2. The colloidal silica-containing polishing liquid has a pH of 3
11. The method for preparing a colloidal silica-containing polishing liquid according to claim 1, wherein the amount of glycerin added is 5 to 40% by weight of the colloidal silica content in the polishing liquid.