JPH0398759A - Polishing pad and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain the highly flat machined surface by jointing finely granulated resin mutually so as to be solidified into plate shape and forming resin particles positioned at the surface layer into such structure as to possess flat faces. CONSTITUTION:Finely granulated thermalplastic resin 1 is filled between two plates 3, 4. The plates 3, 4 are then heated while being pressed from the top and bottom up to the softening temperature of the thermalplastic resin 1 so as to soften the surface layer and form a sintered structure with spaces on its surface and inside. A polishing pad made of finely granulated resin 1 solidified into such a structure as to have spaces on the surface and inside can be thus obtained. In this case, resin particles 1 on the surface layer are provided with flat faces 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a polishing pad used for polishing semiconductor materials and optical materials into a highly flat surface, and a method for manufacturing the same. [Prior Art] Conventionally, polishing pads used when polishing semiconductor materials and optical materials are, for example, materials from the Joint Study Group of the 136th Committee and 145th Committee of the Japan Society for the Promotion of Science.
61.4.18) As stated in the paper published by Kurobe on 15th Page entitled "Characteristics of Bolsha", polyester non-woven fabric impregnated with polyurethane and foamed polyurethane layer on the base (non-woven fabric) are used. The formed one is used. When highly flat polishing is performed using a polyester nonwoven fabric impregnated with polyurethane, the unevenness of the polyester fibers in the surface layer may cause fine roughness on the surface of the workpiece, depending on the polishing conditions. In addition, with polishing pads that have a foamed polyurethane layer formed on the base, fine dents and fuzz on the surface layer may cause deterioration of flatness, and with pads with a thick foaming ratio, the rigidity of the surface layer decreases, making it difficult to process the workpiece. This may cause blurring on the edges of the workpiece, a pad with a low foaming rate may have poor retention of polishing liquid, and processing debris generated during polishing cannot be easily discharged, causing scratches on the surface of the workpiece. There was a case.

[Problem to be solved by the invention]

As described above, it has been difficult for conventional polishing pads to have a high surface flatness, appropriate hardness, retention of the boricinder solution, and dischargeability of polishing debris.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned conventional drawbacks and provide a polishing pad having a highly flat surface, arbitrary hardness, good retention of volocinder liquid, and discharge of polishing debris, and a method for manufacturing the same. .

[Means to solve the problem]

The polishing pad of the present invention has a structure in which fine particles of resin are bonded to each other and solidified into a plate shape, and the resin particles located in the surface layer have a flat surface.

In addition, the method for manufacturing the polishing pad of the present invention involves filling the space between two flat plates with finely granular thermoplastic resin, and heating the thermoplastic resin to its softening temperature while applying pressure from above and below to soften the surface layer. This creates a sintered structure with spaces on the surface and inside. [Operation] The present invention solves the problems of the prior art by taking the above-mentioned precautions. That is, by using an oval polishing pad made of solidified aS granular resin with spaces on the surface and inside, the flatness of the surface, the property of retaining the Boricinda liquid, and the ability to discharge polishing debris are maintained. As a method for manufacturing the polishing pad, a granular thermoplastic resin is filled between two flat plates, and a sintered structure is formed by heating and pressurizing the resin.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic sectional view of a first embodiment of the present invention.

Reference numeral 1 denotes a resin grain having an approximately spherical shape. The resin grain 1 is connected to the adjacent resin grain 1 at a joining part 2, but the structure has a sufficient space between them, and a polishing pad in the form of a thin plate is formed. Configure. And resin particles 1 located in the surface layer
has a flat surface 10.

Figure 2 is a scanning electron micrograph showing the surface condition of one embodiment of the polishing pad of the present invention, with an average particle size of 100 μm.
A polishing pad with a thickness of about 3 mm was made by sintering polyethylene balls.

FIGS. 3(a) to 3(C) are cross-sectional views for explaining a method of cleaning a polishing pad according to a second embodiment of the present invention. Polyethylene grains with an average diameter of 100 μm are filled between the upper plate 3 and lower plate 4 made of stainless steel, which have a highly flat surface.
As shown in Figure (a), a resin layer 5 having a thickness of about 4 mm is formed.

Next, as shown in Figure 3(b), the softening temperature of the resin: 11
While heating to 0° C., pressure is applied from above and below until the thickness becomes about 3 mm to weld the resin particles together and integrate the resin layer 5. Finally, as shown in Figure 1 (C), after cooling the upper plate 3
Then, the lower plate 4 is peeled off and the integrated resin layer 5 is taken out.

As shown in FIG. 1, the polishing pad created in this way has the resin particles 1 welded and integrated, and
The resin particles 1 of the surface layer are crushed by the upper plate 3 and the lower plate 4 and have a flat surface.

In this example, a case was described in which a polishing pad with a thickness of 3 mm was prepared using polyethylene with a particle size of 100 μm, but other types of resin include polybrobylene, polytyl methacrylate, fluororesin, polystyrene, can be used to create polishing pads of various hardnesses. As is clear from the method of preparation, the polishing pad can be prepared under a wide range of conditions regarding particle size, thickness, and porosity.

When a Si wafer with a diameter of 4 inches was processed using the above polishing pad and a colloidal silica aqueous solution as the polishing liquid, the processing speed and surface roughness were the same as those of the polyurethane foam polishing pad, and a flatness of 2 μm was obtained. I was able to get Note that the flatness of conventional polishing pads made of polyurethane foam is 4 to 5 μm. [
Effects of the Invention] As explained above, when polishing is performed using the polishing pad of the present invention, a highly flat processed surface can be obtained. In addition, by using the polishing pad manufacturing method of the present invention, it is possible to obtain a polishing pad with various particle sizes, hardnesses, and porosity, and it is easy to create polishing pads that have the same hardness as polyurethane foam pads, high rigidity, and easy removal of processing waste. can be created.

Furthermore, since the polishing pad of the present invention has a uniform structure in the thickness direction, even if the surface is worn or damaged, it is possible to obtain processing characteristics equivalent to those of a new pad by dressing it. As described above, by using the polishing pad and the method for manufacturing the same of the present invention, it is possible to obtain an excellent polishing pad, which is extremely effective for polishing processing.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a first embodiment of the present invention, and FIG. 2 is a scanning electron micrograph showing the surface condition of an embodiment of the polishing pad of the present invention, and is a diagram showing the structure of polyethylene particles. , and FIGS. 3(a) to 3(c) are cross-sectional views for explaining a method of manufacturing a polishing pad according to a second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Resin grain, 2...Joining part, 3...Top plate, 4...
... Lower plate, 5... Resin layer, 10... Flat surface.

Claims (1)

[Claims] 1. In a polishing pad used when polishing a semiconductor material or optical material to make it highly flat,
Fine particles of resin are joined together and solidified into a plate shape,
A polishing pad characterized in that resin grains located in the surface layer have a structure with a flat surface. 2. Fill the space between two flat plates with finely granular thermoplastic resin, and heat it to the softening temperature of the thermoplastic resin while applying pressure from above and below to soften the surface layer and create a space on the surface and inside. A method for manufacturing a polishing pad characterized by creating a sintered structure.