JP2656400B2 - Surface precision abrasive for hard and brittle materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for finishing hard and brittle materials.
Abrasives used for surface precision polishing with Si, especially Li
Polishing with TaO 3 mechanical wear specific <br/> polishing mechanisms such as _(lithium tantalate) (mechanochemical polishing), semiconductor materials, optical
Material, or a hard and brittle material such as an oxide single crystal material, to a main <br/> Kano abrasive employed for precision polishing to no disturbances mirror with high efficiency.

[0002]

2. Description of the Related Art In recent years, various types of semiconductor materials or optical materials have been developed corresponding to required characteristics. Although this manufacturing process is based on each technique, the final finishing process is generally highly mirror-finished, and is polished by a method based on a polishing mechanism according to the material.

As an example, an industrial example of planar precision polishing in the case of LiTaO ₃ will be described.

[0004] plane precision polishing of such timber fees, pad (made of synthetic fibers or synthetic resin polishing pad) to a platen that rotates adhered to the surface, the polishing object while supplying a polishing agent solution The polishing efficiency and the mirror finished quality of the polished surface have greatly different results depending on the mechanical conditions of the processing and the composition of the supplied abrasive liquid.

[0005] The polishing liquid to be used is generally used mainly for economical reasons, in which the supply and recovery of the polishing liquid are repeated, and the material to be polished is processed several times with the same polishing liquid. Is the way.

Incidentally, the above-mentioned LiTaO ₃ is a typical example.
Hard and brittle materials such as semiconductors and optical materials described in
Is chemically is a very stable material and a material having a property of polishing hardly proceeds via General mechanochemical or mechano precision polishing agent.

[0007] If such a material is polished with a super-hard fine abrasive such as diamond, alumina, boron nitride or silicon nitride, polishing proceeds, but this method has a rough polished surface and cannot be used practically.

In view of the requirement for the accuracy of the polished surface, the highest quality surface can be obtained with a water slurry dispersion of fine silicon dioxide. There is a disadvantage that efficiency is low due to weak power.

Therefore, in the industrial practice, the current state of the art uses a stock solution of high-concentration colloidal silicon dioxide containing, for example, 30% silicon dioxide as a polishing liquid.

[0010]

According to the above-mentioned conventional polishing technique, a high-quality mirror surface of a hard and brittle material can be obtained, and the polishing efficiency can be efficiently secured by using a fresh polishing liquid. This method has a problem that the polishing power (polishing efficiency) decreases with the lapse of time when the abrasive liquid is supplied in a circulating manner, or the polishing power decreases in a short period of time when the material to be polished is replaced and the processing is repeated. is there.

For this reason, each time the polishing process is repeated, the abrasive liquid is replaced with a new one, or the work is continued while replenishing the new abrasive liquid, and as a result, the work is troublesome. Not only that, the maintenance and management of a fixed amount of polishing is complicated, the reproducibility of work is impaired, and as a further disadvantage, a large amount of abrasive liquid is used because high-concentration abrasives are used and frequent replacement and replenishment are required. Need, waste of resources and economic problems.

The present inventor has solved the above-mentioned problems of the conventional surface precision abrasive for hard and brittle materials, and circulates and supplies the abrasive liquid while having an efficient and excellent polishing action. The present invention has been completed for the purpose of providing a novel surface polishing agent in which the polishing performance is less reduced even when the polishing process is repeated.

[0013]

The feature of the surface precision abrasive according to the present invention, which has been made to achieve this object, is that:
Mirror surface of semiconductor material, optical material, oxide single crystal material
This is a surface precision abrasive used for mechanic polishing.
And produced by a precipitation method, and has a BET specific surface area of 10 to 10.
60 m 2 / ^g, and an average particle diameter of 0.5~5μm finely divided silicon dioxide secondary particles as measured by a Coulter counter method, 1-20% of the concentration in the aqueous slurry dispersion dispersed in water There is a feature .

[0014] Compared to the above surface precision abrasive of the present invention
Te, the particulate silicon dioxide, which is produced Ri by the same precipitation method
Even when used , the BET specific surface area is 60 m ² / g
In the case of polishing using a higher silicon dioxide slurry dispersion, as will be seen from the comparison of Examples and Comparative Examples described later.
In addition, although a high-quality mirror surface can be obtained, the polishing efficiency is low, so that practically preferable performance can not be obtained. Further, even when the secondary particles are fine and the BET specific surface area is in the range of 10 to 60 m ² / g, In a silicon dioxide slurry dispersion manufactured by another manufacturing method such as a dry method, when the abrasive solution is supplied in a circulating manner, the polishing efficiency is reduced in a short period of time, and any desired performance is not obtained. No.

The fine particulate precipitated silicon dioxide concentration of the aqueous slurry dispersion of abrasive is 1-20% of the concentration range odor
Te, the higher the concentration, there is a tendency that the polishing efficiency is high.

The material to be polished to which the abrasive according to the present invention is applied is typically an oxide single crystal, but is not particularly limited thereto. High wear-polishing properties can be used as a substance.
Further, in order to improve use or performance, an alkali agent or an oxidizing agent may be used in combination, or an agent such as a surfactant may be added, and the present invention is not limited thereto.

[0017]

The abrasive of the present invention has the above-mentioned structure, and can be used as a semiconductor material, an optical material, and an acid, which are hard and brittle materials.
Abrasive that mirror-processes the surface of a single-crystal material, and exhibits a high polishing efficiency with low-concentration silicon dioxide that could not be achieved with conventional abrasives. Can be maintained for a long time.

[0018]

The present invention will be described below more specifically with reference to examples and comparative examples. The physical properties of the silicon dioxide used in the polishing slurry, the preparation of the polishing slurry and the polishing test were carried out by the following methods.

Physical properties of silicon dioxide BET specific surface area is determined by Cantersoap (Quantachrome, USA).
Was measured by the one-point method. The average particle diameter (volume average diameter) of the secondary particles was measured using a Coulter Counter TA-
Using II (manufactured by Coulter Electronics Ins.), The measurement was performed with a 30 μ aperture tube.

Preparation of Abrasive Liquid A certain amount of silicon dioxide was added to a certain amount of pure water, and the mixture was stirred well to obtain a slurry liquid as a uniform slurry dispersion.

Polishing Test In the polishing test, a 0.7 mm thick LiTaO ₃ single crystal substrate was cut into 15 mm squares, and three substrates were bonded at equal intervals to an adhesive plate (2700 g) having a diameter of 100 mm. Polishing machine (small surface polishing machine; FPM-30 manufactured by Copal Electronics)
A pad made of a polyurethane-impregnated polyester non-woven fabric was attached to the surface of a platen (diameter: 300 mm), and the adhesive plate was placed on the pad. Next, each abrasive solution was applied for 0.1 hour to 0.1 mL.
While the solution was dropped at a rate of 5 liters, the rotating speed of the platen was 60 rpm, and the polishing pressure was 400 g / cm ² by a modified wheel type polishing machine.
Under the conditions described above, the surface of the LiTaO ₃ was polished for 1 hour.
The entire amount of the polishing liquid used during this period was recovered, and then polishing of LiTaO ₃ was repeated five times under the same conditions as above, and the performance change of the polishing liquid due to long-term use was determined.

Measurement of polishing performance The polishing rate is determined based on the material to be polished Li before and after the polishing test.
The thickness of TaO ₃ was measured with a micrometer, and the polishing speed per hour was determined from the difference in the thickness. In addition, the degree of specularity of the finished surface by polishing was visually judged.

Examples 1 to 3 In Examples 1 and 2, 10% of silicon dioxide (nip seal E-743) having a BET specific surface area of 42 m ² / g and an average secondary particle size of 1.5 μm produced by the precipitation method. And a 15% aqueous slurry dispersion as an abrasive liquid, and in Example 3, the respective physical property values of 50 m ² /
g, 1.8 μm silicon dioxide (Nip Seal E-7)
5; a polishing test of LiTaO ₃ was performed using a 15% aqueous slurry dispersion of Nippon Silica Kogyo Co., Ltd. as an abrasive solution, and the results are shown in Table 1 below.

From the results of Examples 1 and 2, the higher the concentration of silicon dioxide in the slurry of the polishing slurry, the faster the polishing rate. At a concentration of 15%, the polishing rate was higher than that of the comparative example, and was stabilized by repeated polishing. It was shown that the polishing rate was maintained. Regardless of the mirror finish of the finished surface including the comparative example, the same high quality mirror surface was obtained.

Comparative Examples 1 and 2 In Comparative Example 1, silicon dioxide (nip seal E-220A) having a BET specific surface area of 130 m ² / g and an average secondary particle diameter of 1.4 μm produced by the precipitation method was used. In Example 2, each physical property value was 95 m ² /
g, 4.0 μm silicon dioxide (Nip Seal E-15)
The same polishing test was carried out for the case where a 15% aqueous slurry dispersion (0J; both manufactured by Nippon Silica Kogyo Co., Ltd.) was used as an abrasive liquid, and the results are shown in Table 1 below. In these examples, the precipitated silicon dioxide having a high BET specific surface area resulted in a low polishing rate regardless of the particle diameter of the secondary particles.

Comparative Example 3 A colloidal dispersion (colloidal silica) containing 30% of silicon dioxide having a particle diameter of 0.08 μm was subjected to a polishing test using a stock solution which was not diluted. The results are shown in Table 1 for comparison.

The polishing rate in the case of colloidal silicon dioxide having different production shapes showed no concentration effect irrespective of the high slurry concentration, and it was shown that the performance was greatly reduced especially by repeated polishing.

[0028]

[Table 1]

As is clear from the results in Table 1 above,
When the abrasive of the present invention is used, a high polishing rate can be obtained by a silicon dioxide slurry dispersion having a relatively low concentration, and the performance is reduced little by repeated use of the abrasive liquid. This shows that an abrasive having the effect of stably performing the polishing process can be provided.

Continued on the front page (51) Int.Cl. ⁶ Identification code Reference number in the agency FI Technical display location H01L 21/304 321 H01L 21/304 321P 21/463 21/463

Claims (1)

(57) [Claims] 1. Semiconductor material, optical material, oxide single crystal material
Surface refinement used for mechano-polishing for mirror-finish
A fine abrasive which is produced by a precipitation method , has a BET specific surface area of 10 to 60 m ² / g, and has an average secondary particle diameter of 0.5 to 5 μm as measured by a Coulter counter method. In water at a concentration of 1-20%
Table surface precision abrasive you characterized in that an aqueous slurry dispersion