Polishing pad and method of polishing a semiconductor wafer

Abstract

A polishing pad, a polishing laminated pad and a semiconductor wafer polishing method all of which prevent a leak of slurry from the gap between a polishing substrate and a reduction in polishing efficiency caused by a scratched and a window member and enable the optical detection of the polishing end point to be carried out efficiently. The polishing pad comprises a polishing substrate having a through hole extending from the front side to the rear side and a light transmitting member arranged in the through hole, and the outer wall of the above light transmitting member and the inner wall of the though hole opposite to the outer wall are bonded together with a photocurable adhesive such as a polyurethane(meth)acrylate to fix the above light transmitting member in the through hole.

Description

[0001] The present invention relates to a polishing pad and a method of polishing a semiconductor wafer. More specifically, it relates to a polishing pad comprising a window member for optical end-point detection, which prevents a leak of slurry from the gap between a polishing pad substrate and the window member and which enables the optical detection of the polishing end point to be carried out efficiently without a reduction in polishing efficiency caused by a scratched surface to be polished and to a method of polishing a semiconductor wafer with the polishing pad.DESCRIPTION OF THE PRIOR ART[0002] In the polishing of a semiconductor wafer, after the purpose of polishing is accomplished, the determination of the polishing end point for terminating polishing can be made based on a time obtained empirically. However, various materials are used to form surfaces to be polished and the polishing time differs by each material. It is conceivable that the material forming the surface to...

AI Technical Summary

Benefits of technology

[0008] The inventors of the present invention have conducted intensive studies on a polishing pad used for polishing, making use of an optical end-point detection device, specifically a method of fixing a window member to a polishing pad and have found that efficient polishing can be carried out through optical end-point detection by bonding and fixing a light transmitting member as the window member in a polishing pad substrate without a gap between them with a photocurable adhesive to prevent a leak of slurry from the gap during polishing and a bad phenomenon such as scratching. The present invention has been accomplished based on this finding.

Problems solved by technology

Therefore, it is extremely inefficient to obtain the polishing time from these.

This polishing pad has a problem that optical end-point detection may become unsatisfactory due to a leak of slurry from the gap between the window member and the polishing pad substrate because the window member becomes loose during polishing.

However, it involves the following problems: (1) the curing of the adhesive takes long, thereby reducing the production yield, and (2) the window member is distorted by the swelling of the adhesive at the time of curing, whereby part of the window member may project from the surface of the polishing pad substrate and accordingly, a polishing pad having a smooth surface may not be obtained.

Meanwhile, when rubber cement or a commonly used adhesive such as an epoxy-based adhesive is used, part of the adhesive may be solidified while it overflows into the polishing surface of the polishing pad or part of the adhesive solidified during polishing may fall off as a fragment, thereby scratching the surface to be polished.

When the average particle diameter is larger than 500 .mu.m, the formed pores become too large, whereby the mechanical strength and polishing rate of the obtained polishing pad may lower.

When the content of the water-soluble substance (B) is higher than 90 vol %, it may be difficult to completely prevent the water-soluble substance (B) dispersed in the water-insoluble matrix material (A) from being gelled or dissolved one after another during polishing and therefore to maintain the hardness and mechanical strength of the polishing substrate at appropriate values.

When the above through hole is shorter than the above length, it may be difficult for the through hole to transmit light such as light for end-point detection.

However, it may be difficult to obtain a desired Shore D hardness only from the above water-insoluble matrix material (A).

When the content of the water-soluble substance (B) is lower than 0.1 vol %, the number of pores formed during polishing is small and a desired polishing rate is hardly obtained.

When the content is larger than 90 vol %, the polishing pad may become too fragile.

When the thickness is smaller than 0.1 mm, it is difficult to secure sufficiently high mechanical strength for the light transmitting member.

When the viscosity is higher than 100,000 mPa.s, the flowability may lower and the work efficiency may deteriorate.

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