JP2009160716A - Polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem of a conventional polishing pad: there occurs a precision-level difference in surface roughness, parallelism and flatness within one workpiece due to a peripheral velocity difference between an inner-periphery portion and an outer-periphery portion of a carrier because the carrier having a substantial thickness of a velour and used in a planetary gear type polishing machine, performs circular movement of autorotation and revolution. <P>SOLUTION: By forming the polishing pad into a doughnut shape and changing the substantial thickness of the velour, variations in surface roughness of a polishing surface in the outer-periphery portion and the inner-periphery portion of the workpiece are reduced, and uniform precision of parallelism and flatness is provided. Thus high production efficiency is achieved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing pad used in a polishing apparatus that performs mirror polishing of various substrates such as semiconductors such as silicon and gallium arsenide, glass, and metal.

  Conventionally, a planetary gear type plane polishing apparatus for polishing a glass plate, a silicon wafer or the like includes an upper plate, a lower plate, a carrier, a sun gear, and an internal gear. A velor type polishing cloth, which is a non-woven fabric impregnated with polyurethane resin, is attached to a processed surface of the upper plate and the lower plate through a double-sided adhesive tape.

Also, to improve the performance of the polishing pad, the polishing cloth or the polishing surface of the polishing pad is re-polished to improve the surface condition, the surface is grooved by mechanical processing, or a pad with many long pores. To be done.
JP-A-11-77518 JP-A-11-285963 JP2000-42901

  In the case of a planetary gear type plane polishing apparatus that polishes an object to be polished in batch mode, it is mounted on a carrier and several tens of sheets are simultaneously polished. The uniformity of accuracy within a batch of one carrier, such as the fineness of the polished surface, parallelism and flatness, and the diameter of the object to be polished reach from 300 mm to 450 mm. Although demanded in recent years, the work after processing with the conventional pad has the surface roughness and parallel / flatness of the work at the outer periphery and inner periphery of the carrier and the center and outer periphery of the large diameter work. There will be a difference in accuracy.

  The present invention provides a polishing pad that meets the demand for higher accuracy after workpiece polishing and aims to improve the accuracy and shorten the production process.

  In order to solve the above-mentioned problems, the present invention is a velor-like pad used by being attached to a polishing plate, wherein the substantial difference in the thickness of the velor part of the doughnut-shaped band is changed by 10 to 15% between the adjacent ones. A polishing pad in which 2 to 5 bands are formed is provided.

  The polishing pad is impregnated with a polyurethane resin by a wet coagulation method on a needle-punched polyester web, coagulated, washed with water, dried and polished to a predetermined thickness by a sanding machine to produce a velor sheet.

  A film obtained by punching out a polyester film into a donut shape is pasted on one side of a velor sheet that has been cut into a single sheet, and a double-sided tape is further pasted on that side. The velor surface is then finished to a uniform thickness using a sanding machine. By polishing, the velor surface is made thinner by the thickness of the polyester film. By this principle, the polishing pad formed by changing the substantial thickness of the velor portion in a donut shape, the difference in the substantial thickness of the velor portion of the donut-shaped belt changes by 10 to 50% between adjacent ones, the donut-shaped belt The target is a polishing pad in which 2 to 5 are formed.

  As the velor used in the present invention, a known velor made by impregnating a resin such as a synthetic rubber or polyurethane into a web such as a needle-punched polyester fiber can be used. A fine polyurethane velor made of polyurethane produced by a wet coagulation method is preferred. Polyurethane can be produced by a known wet process using polyester polyurethane, polyether polyurethane, or polycarbonate based polyurethane alone or in combination. Various additives such as pigments can be mixed in the urethane layer.

  Furthermore, a suede type polishing cloth is usually used by attaching a double-sided tape to the back of a non-woven fabric and attaching it to a polishing machine.

A 3.3 decitex polyester fiber web having a fiber length of 50 mm was needle punched to produce a fiber sheet having a thickness of 1.7 mm, an apparent density of 0.13 gcm ² , and a weight of 270 gcm ² . Next, 100 parts of a polyester polyurethane resin having a solid content of 30%, a 10% aqueous solution solidified layer of dimethylformamide called DMF, solidified, battlefield, dried and polished on both sides with a belt sander machine, Got velour.

In the present invention, the above-mentioned velor is cut into a 1300 mm square, and a polyester film having a total thickness of 230 μm with an adhesive on one side is attached to one side of a velor cut to an inner diameter of 500 mm so as to be centered. Acrylic double-sided tape using a film was applied to the surface. Thereafter, 280 μm was ground from the velor surface using # 120 paper with a polishing machine. The actual velor thickness of the obtained velor type polishing cloth was 1.15, 0.92, and 1.15 mm from the inside. Further, a single polishing pad was obtained by extracting to 1200 mmφ with Thomson.
Further, the obtained pad can be subjected to drilling, grooving and the like as usual.

The polishing pad of the present invention is mounted on a planetary gear type planar polishing apparatus, and finish polishing of a 4-inch silicon wafer is processed 10 batches by 100 batches.
As a result, there was little variation in surface roughness, parallelism and flatness, the rework rate was reduced by 20% compared to the apparatus not using the polishing pad of the present invention, and the process was shortened.

It is a layer sectional view of the polishing pad of the present invention. It is explanatory drawing which showed an example of embodiment of this invention and stuck the polishing pad on the polishing plate, and was seen from the state of a workpiece | work and a carrier right above. It is sectional drawing which affixed the polishing pad of this invention on the polishing plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polishing plate 11 Work 12 Carrier 13 Polishing pad 14 Polyester film 15 Double-sided tape

Claims (3)

A velor-like polishing pad that is used to polish a workpiece and is attached to the polishing plate of a polishing device. A donut-shaped polyester film is laminated on the back surface to change the substantial thickness of the velor part. A polishing pad that is formed. The polishing pad according to claim 1, wherein the substantial difference in thickness of the velor portion of the doughnut-shaped band is changed by 10 to 50% between adjacent ones. The polishing pad according to claim 1, wherein 2 to 5 donut-shaped bands are formed.

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