Methods for making chemical mechanical planarization (cmp) polishing pads having integral windows

Abstract

The present invention provides methods of making a chemical mechanical planarization (CMP) polishing layer or pad comprising providing an open mold having a surface with a female topography that generates a flat or shaped CMP polishing layer surface and having held in place thereon one or more endpoint detection window pieces; mixing a liquid isocyanate component with a liquid polyol component to form a solvent free reaction mixture; spraying the reaction mixture onto the open mold while the one or more window pieces is held in place, with each window piece at a predefined location, followed by curing the reaction mixture.

We claim: 
     
         1 . A method of making a chemical mechanical planarization (CMP) polishing layer or pad comprising:
 providing an open mold having a surface with a female topography that generates a flat or shaped CMP polishing layer surface and having held in place thereon one or more window pieces;   mixing a liquid isocyanate component with a liquid polyol component to form a solvent free reaction mixture;   spraying the reaction mixture onto the open mold while the one or more window pieces is held in place, with each window piece at a predefined location, followed by;   curing the reaction mixture to form a gel polishing layer from the reaction mixture, demolding, and curing the gel polishing layer to form a polyurethane reaction product as a CMP polishing layer.   
     
     
         2 . The method as claimed in  claim 1 , wherein the one or more window pieces is masked or blocked on the back side away from the open mold surface, thereby preventing buildup of the reaction mixture on the masked or blocked side of the window pieces and eliminating the need for back side facing to expose the surface of the window pieces. 
     
     
         3 . The method as claimed in  claim 1 , wherein the reaction mixture has a gel time at 80° C. of from 2 to 600 seconds. 
     
     
         4 . The method as claimed in  claim 1 , wherein the curing comprises:
 initially curing to form the gel polishing layer at from ambient temperature to 130° C. for a period of from 30 seconds to 30 minutes;   demolding the gel polishing layer from the open mold surface, and, then;   finally curing at a temperature from 60 to 130° C. for a period of 1 minutes to 16 hours to form a porous polyurethane reaction product as a CMP polishing layer having one or more endpoint detection windows and having a density ranging from 0.5 gm/cc to 1 gm/cc.   
     
     
         5 . The method as claimed in  claim 1 , wherein the one or more window pieces comprises a polyurethane chosen from one formed from the reaction of a polyol with an aromatic, aliphatic or cycloaliphatic diisocyanate or polyisocyanate, or one formed from a isocyanate terminated urethane prepolymer, or one formed from a two-component reaction mixture of an isocyanate component and a polyol component. 
     
     
         6 . The method as claimed in  claim 5 , wherein the one or more window pieces comprises a polyurethane chosen from (i) the product of a polyol component and an isocyanate component containing 2 wt. % of less of aromatic isocyanate groups, based on the total weight of the polyol in the polyol component and the isocyanate in the isocyanate component. 
     
     
         7 . The method as claimed in  claim 1 , wherein the window piece has a hardness ranging from a Shore D hardness using Rex Type D gauge of 15 to 90. 
     
     
         8 . The method as claimed in  claim 1 , wherein the CMP polishing layer has a Shore D hardness Rex Type D gauge ranging from 15 to 90. 
     
     
         9 . The method as claimed in  claim 1 , wherein each of the one or more window pieces is round, square, rectangular or polygonal and the open mold has a flat area or recess adapted to accommodate and having the same outer dimension as each of the one or more window pieces. 
     
     
         10 . The method as claimed in  claim 1 , wherein the one or more window pieces is held in place on the surface of the open mold by any of: applying vacuum to the underside of the one or more window pieces during spraying and curing to form a gel polishing layer, applying adhesive or double sided tape to the open mold where the one or more window pieces is placed on the open mold, and providing the open mold with a flat area or pocket that is slightly recessed from the surrounding surface of the open mold and sized to allow the one or more window pieces to fit tightly into place in the open mold. 
     
     
         11 . The method as claimed in  claim 1 , wherein the reaction mixture is substantially water free.