Chemical mechanical polishing pad

Abstract

A chemical mechanical polishing pad is provided containing: a polishing layer; a rigid layer; and, a hot melt adhesive bonding the polishing layer to the rigid layer; wherein the polishing layer exhibits a specific gravity of greater than 0.6; a Shore D hardness of 60 to 90; an elongation to break of 100 to 300%; and, a unique combination of an initial hydrolytic stability and a sustained hydrolytic instability.

We claim: 
     
         1 . A chemical mechanical polishing pad, comprising:
 a polishing layer having a polishing surface, a base surface and an average thickness, T P-avg , measured in a direction perpendicular to the polishing surface from the polishing surface to the base surface;   wherein the polishing layer is a cast polyurethane, wherein the cast polyurethane is a reaction product of ingredients, comprising:
 (a) an isocyanate terminated prepolymer obtained by reaction of:
 (i) a polyfunctional isocyanate; and, 
 (ii) a polyether based polyol; 
 wherein the isocyanate terminated prepolymer has 8 to 9.5 weight percent unreacted NCO; 
 
 (b) a curative agent, wherein the curative agent is selected from the group consisting of curative polyamines, curative polyols, curative alcoholamines and mixtures thereof; and, 
 optionally, (c) a plurality of microelements; 
   wherein the polishing layer exhibits a specific gravity of greater than 0.6; a Shore D hardness of 60 to 90; and, an elongation to break of 100 to 300%;   wherein the polishing layer exhibits an initial hydrolytic stability, wherein a linear dimension of a sample of the polishing layer changes by <1% following immersion in deionized water for 24 hours at 25° C.;   wherein the polishing layer exhibits a sustained hydrolytic instability, wherein the linear dimension of the sample of the polishing layer changes by ≧1.75% following immersion in deionized water for seven days at 25° C.;   a rigid layer having a top surface and a bottom surface;   a hot melt adhesive interposed between the base surface of the polishing layer and the top surface of the rigid layer; wherein the hot melt adhesive bonds the polishing layer to the rigid layer;   a pressure sensitive platen adhesive layer having a stack side and a platen side;   wherein the stack side of the pressure sensitive platen adhesive layer is adjacent to the bottom surface of the rigid layer; and,   optionally, a release liner; wherein the optional release liner is disposed on the platen side of the pressure sensitive platen adhesive layer.   
     
     
         2 . The chemical mechanical polishing pad of  claim 1 , wherein the curative and the isocyanate terminated prepolymer have an OH or NH 2  to unreacted NCO stoichiometric ratio of 80 to <95 percent. 
     
     
         3 . The chemical mechanical polishing pad of  claim 1 , wherein the top surface and the bottom surface of the rigid layer are ungrooved. 
     
     
         4 . The chemical mechanical polishing pad of  claim 1 , wherein the rigid layer has a Young's Modulus of 2,500 to 7,500 MPa. 
     
     
         5 . The chemical mechanical polishing pad of  claim 2 , wherein the rigid layer is made of a biaxially oriented polyethylene terephthalate; wherein the rigid layer has an average thickness of 6 to 15 mils; and, wherein the rigid layer exhibits a Young's Modulus of 3,000 to 7,000 MPa. 
     
     
         6 . The chemical mechanical polishing pad of  claim 5 , wherein the cast polyurethane is the reaction product of ingredients, comprising: (a) the isocyanate terminated prepolymer obtained by reaction of: (i) the polyfunctional isocyanate; and, (ii) the polyether based polyol; wherein the isocyanate terminated prepolymer has >8.7 to 9 weight percent unreacted NCO; (b) the curative agent, wherein the curative agent is a curative polyamine; and, (c) the plurality of microelements; wherein the polishing layer exhibits a specific gravity of greater than 0.6; a Shore D hardness of 61 to 75; and, an elongation to break of 100 to 200%. 
     
     
         7 . The chemical mechanical polishing pad of  claim 6 , further comprising: an endpoint detection window. 
     
     
         8 . The chemical mechanical polishing pad of  claim 7 , wherein the endpoint detection window is an integral window. 
     
     
         9 . The chemical mechanical polishing pad of  claim 7 , wherein the endpoint detection window is a plug in place window. 
     
     
         10 . A method of polishing a substrate, comprising:
 providing a substrate selected from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate;   providing a chemical mechanical polishing pad according to  claim 1 ;   creating dynamic contact between a polishing surface of the polishing layer and the substrate to polish a surface of the substrate; and,   conditioning of the polishing surface with an abrasive conditioner.