Polishing pads and methods relating thereto

Details Polishing pads and methods relating thereto Polishing pads and methods relating thereto

2001-03-22

2001-12-04

Banks, Derris H. (Department: 3723)

Abrading

Abrading process

Glass or stone abrading

C451S526000

Reexamination Certificate

active

06325703

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to polishing pads which are useful in the polishing of semiconductor wafers, integrated circuits and the like. More specifically, the polishing pads of the present invention are directed to the use of sintered thermoplastic particles to enhance polishing performance.
2. Description of Related Art
U.S. Pat. No. 3,763,054 discloses microporous polyurethane sheeting by melt sintering sheets of loosely bonded particles.
U.S. Pat. No. 3,917,761 discloses a process of preparing porous sintered polyimide articles useful as oil filled bearings.
U.S. Pat. No. 4,256,845 discloses a method for manufacturing a porous thermoplastic sheet by gelling an aqueous latex dispersion of particles and forming the dispersion into a sheet. This sheet is then free-sintered at a temperature at or above the melting point of the thermoplastic to form the final product.
U.S. Pat. No. 4,880,843 discloses a process for preparing a porous molded composite article containing ultra high molecular weight polyethylene and a polyethylene wax. The powder is melt sintered at a temperature in excess of the melting point of the polymer.
SUMMARY OF THE INVENTION
The present invention is directed to polishing pads comprising sintered thermoplastic particles. The particles comprise a thermoplastic material having a critical surface tension greater than or equal to 34 milliNewtons per meter, a modulus of 1 to 200 megaPascals and an elongation to break in the range of 25% to 1000%. The particles are compacted into a mold having the desired final pad dimensions at a pressure in excess of 100 psi, and the particles are then sintered at a temperature above the glass transition temperature, but preferably below the melting point of the thermoplastic.


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SurfaceTech Review, Rodel Products Corporation, vol. 1, Issue 1, pp. 1 and 2, Dec. 1986.

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