Polishing pad, composition for the manufacture thereof, and method of making and using

Abstract

A polyurethane layer for forming a polishing pad for a semiconductor wafer is described, wherein the polyurethane layer comprises: a foamed polyurethane, wherein the polyurethane foam has a density of about 640 to about 960 kg/m 3 , and a plurality of cells having an average diameter of about 20 to about 200 micrometers; and particles of a hydrophobic polymer having a critical surface energy of less than 35 mN/m and having a median particle size of 3 to 100 micrometers. Polishing pads as well as methods for polishing are also described.

1 - 15 . (canceled) 
     
     
         16 . A polishing pad, comprising a polyurethane layer, wherein the polyurethane layer comprises a polyurethane foam, wherein the polyurethane foam has
 a density of about 640 to about 1200 kg/m 3 , and   a plurality of cells having an average diameter of 20 to 200 micrometers, and   the polyurethane layer has:   a KEL of about 1 to about 500 1/Pa at 50° C.,   a storage modulus of greater than 100 MPa in the range of 20° C. to 50° C.,   a tan δ of less than 0.070 in the range of 20° C. to 50° C.,   and a ratio of tan δ at 50° C.:tan δ at 20° C. of 1.2 to 3.0;   wherein the polyurethane layer functions as a polishing layer of the polishing pad, which polishing pad is capable of use for planarizing a work piece in conjunction with a chemical-mechanical polishing apparatus.   
     
     
         17 . The polishing pad of  claim 16 , wherein the surface energy of the polyurethane layer as produced is 18 to 30 mN/m. 
     
     
         18 . The polishing pad of  claim 16 , wherein the polyurethane is produced in the presence of a ferric acetyl acetonate catalyst. 
     
     
         19 - 20 . (canceled) 
     
     
         21 . The polishing pad of  claim 16 , wherein the pad exhibits a defect rate of less than 3500 based on a 0.25 μm cutoff. 
     
     
         22 . The polishing pad of  claim 16 , wherein the pad exhibits a defect rate of less than 20000 at a 0.20 μm cutoff. 
     
     
         23 . The polishing pad of  claim 16 , wherein the polishing surface has been ground to remove the skin from the surface of a polishing pad. 
     
     
         24 . The polishing pad of  claim 16 , wherein the polishing surface of the polishing layer further comprises grooves. 
     
     
         25 . The polishing pad of  claim 16 , wherein the polishing pad is a composite pad comprising the polishing layer disposed on a substrate layer of another polyurethane foam or elastomeric material that is integrally bonded to the polishing layer. 
     
     
         26 . The polishing pad of  claim 16 , wherein the polyurethane foam has been made by a process comprising mechanical frothing. 
     
     
         27 . A method of planarizing a surface of a work piece, comprising applying a particulate media against said surface, and rotating, relative to said surface, the polishing pad of  claim 16 . 
     
     
         28 . The method of  claim 27 , wherein polishing is by means of a polishing machine employing a down force of 35 to 700 g/cm 2 , a platen speed of 25 to 400 rpm, a carrier speed of 25 to 400 rpm, and a media flow of 20 to 500 mL/min. 
     
     
         29 . The polishing pad of  claim 16 , wherein the polyurethane foam is the reaction product of
 an isocyanate-containing component;   an active hydrogen-containing component reactive with the isocyanate-containing component, and comprising a polyether polyol of the formula R[(OC n H 2n ) z OH] a , wherein R is hydrogen or a polyvalent hydrocarbon radical; a is 2-8 and equal to the valence of R; n in each occurrence is an integer from 2-4; and z in each occurrence is 2 to about 200;   a silicone surfactant, and   a catalyst for curing of the foam.   
     
     
         30 . The polishing pad of  claim 29 , wherein the isocyanate-containing component comprises a prepolymer that comprises the reaction product of a diisocyanate compound with glycol. 
     
     
         31 . The polishing pad of  claim 29 , wherein the polyether polyol is polytetramethylene ether glycol. 
     
     
         32 . The polishing pad of  claim 29 , wherein the active hydrogen-containing component further comprises a diol chain extender. 
     
     
         33 . The polishing pad of  claim 29 , wherein the surfactant is a nonhydrolyzable silicone glycol copolymer. 
     
     
         34 . The polishing pad of  claim 16 , wherein the polyurethane foam has a density of 640 to about 960 kg/m 3 . 
     
     
         35 . The polishing pad of  claim 16 , wherein the polyurethane layer has a thickness of 0.5 to 5.0 mm. 
     
     
         36 . The polishing pad of  claim 16 , wherein the polishing layer is adapted for polishing a microelectronic work piece of a work piece comprising a semiconductor base material. 
     
     
         37 . The polishing pad of  claim 16 , wherein the polyurethane foam further comprises particles of a hydrophobic polymer having a critical surface energy of less than 35 mN/m and having a median particle size of 3 to 100 micrometers.