Chemical mechanical polishing pad

Abstract

A chemical mechanical polishing pad is provided containing a polishing layer having a polishing surface, wherein the polishing layer comprises a reaction product of ingredients, including: an isocyanate terminated urethane prepolymer; and, a curative system, containing a high molecular weight polyol curative; and, a difunctional curative.

We claim: 
     
         1 . A chemical mechanical polishing pad, comprising:
 a polishing layer having a polishing surface, wherein the polishing layer comprises a reaction product of ingredients, comprising:
 an isocyanate terminated urethane prepolymer having 8.5 to 9.5 wt % unreacted NCO groups; and, 
 a curative system, comprising:
 10 to 60 wt % of a high molecular weight polyol curative, wherein the high molecular weight polyol curative has a number average molecular weight, M N , of 2,500 to 100,000; and wherein the high molecular weight polyol curative has an average of 3 to 10 hydroxyl groups per molecule; and, 
 40 to 90 wt % of a difunctional curative. 
 
   
     
     
         2 . The chemical mechanical polishing pad of  claim 1 , wherein the polishing surface is adapted for polishing a substrate selected from the group consisting of at least one of a magnetic substrate, an optical substrate and a semiconductor substrate. 
     
     
         3 . The chemical mechanical polishing pad of  claim 1 , wherein the curative system has a plurality of reactive hydrogen groups and the isocyanate terminated urethane prepolymer has a plurality of unreacted NCO groups; and, wherein a stoichiometric ratio of the reactive hydrogen groups to the unreacted NCO groups is 0.85 to 1.15. 
     
     
         4 . The chemical mechanical polishing pad of  claim 1 , wherein the polishing layer exhibits a density of greater than 0.6 g/cm 3 ; a Shore D hardness of 40 to 60; an elongation to break of 125 to 300%; a G′ 30/90 ratio of 1.5 to 4; a tensile modulus of 100 to 300 (MPa); a wet cut rate of 4 to 10 μm/min; and, a 300 mm TEOS removal rate to Shore D hardness ratio (TEOS 300-RR /Shore D hardness) of ≧28. 
     
     
         5 . The chemical mechanical polishing pad of  claim 4 , wherein the isocyanate terminated urethane prepolymer has 8.95 to 9.25 unreacted NCO groups. 
     
     
         6 . The chemical mechanical polishing pad of  claim 2 , wherein the polishing surface has a spiral groove pattern formed therein. 
     
     
         7 . A method of making a chemical mechanical polishing pad according to  claim 1 , comprising:
 providing an isocyanate terminated urethane prepolymer having 8.5 to 9.5 wt % unreacted NCO groups; and,   providing a curative system, comprising:
 10 to 60 wt % of a high molecular weight polyol curative, wherein the high molecular weight polyol curative has a number average molecular weight, M N , of 2,500 to 100,000; and wherein the high molecular weight polyol curative has an average of 3 to 10 hydroxyl groups per molecule; and, 
 40 to 90 wt % of a difunctional curative; and, 
   combining the isocyanate terminated urethane prepolymer and the curative system to form a combination;   allowing the combination to react to form a product;   forming a polishing layer from the product; and,   forming the chemical mechanical polishing pad with the polishing layer.   
     
     
         8 . The method of  claim 7 , further comprising:
 providing a plurality of microelements;   wherein the plurality of microelements is combined with the isocyanate terminated urethane prepolymer and the curative system to form the combination.   
     
     
         9 . A method of polishing a substrate, comprising:
 providing a chemical mechanical polishing apparatus having a platen;   providing at least one substrate;   providing a chemical mechanical polishing pad according to  claim 1 ;   installing onto the platen the chemical mechanical polishing pad;   optionally, providing a polishing medium at an interface between the polishing surface and the substrate;   creating dynamic contact between the polishing surface and the substrate, wherein at least some material is removed from the substrate.   
     
     
         10 . The method of  claim 9 , wherein the at least one substrate is selected from the group consisting of at least one of a magnetic substrate, an optical substrate and a semiconductor substrate.