Pressure controlled polishing platen

Abstract

A method and apparatus for controlling pressure or forces applied to a substrate in a polishing process is described. In one embodiment, a polishing system is described. The system includes a platen rotatably disposed on a base, the platen having a sidewall and a polishing pad disposed thereon forming an interior volume, and a pad pressure applicator disposed in the interior volume of the platen adjacent the underside of the polishing pad.

1 . A polishing system, comprising:
 a platen rotatably disposed on a base, the platen having a sidewall and a polishing pad secured to the platen at a perimeter thereof to form an interior volume; and   a pad pressure applicator disposed in the interior volume of the platen adjacent an underside of the polishing pad.   
     
     
         2 . The system of  claim 1 , wherein the pad pressure applicator further comprises a plate having a plurality of perforations adapted to direct a fluid against the underside of the polishing pad. 
     
     
         3 . The system of  claim 2 , wherein the plurality of perforations are coupled to a pressure source. 
     
     
         4 . The system of  claim 3 , wherein the pressure source comprises one or more chambers disposed in a housing. 
     
     
         5 . The system of  claim 1 , wherein the pad pressure applicator further comprises one or more concentric rings adapted to contact the underside of the polishing pad. 
     
     
         6 . The system of  claim 1 , further comprising: a flexible membrane adapted to contact the underside of the polishing pad. 
     
     
         7 . The system of  claim 6 , wherein the flexible membrane is coupled to a perimeter of the platen by one or more tensioner devices. 
     
     
         8 . The system of  claim 7 , wherein the pad pressure applicator provides an air bearing between the flexible membrane and the pad pressure applicator. 
     
     
         9 . The system of  claim 8 , wherein the air bearing comprises multiple, laterally spaced pressure zones. 
     
     
         10 . The system of  claim 1 , wherein the pad pressure applicator is movable relative to the underside of the polishing pad. 
     
     
         11 . A method for polishing a substrate, comprising:
 urging a substrate against a first surface of a polishing pad using a first pressure applied from a first pressure applicator to a backside of the substrate; and   applying a second pressure from a second pressure applicator to a feature side of the substrate through a second surface of the polishing pad.   
     
     
         12 . The method of  claim 11 , wherein the substrate is movable in a sweep pattern across the first surface of the polishing pad and the second pressure is in communication with the substrate as the substrate moves in the sweep pattern. 
     
     
         13 . The method of  claim 12 , wherein the second pressure applicator is movable with the substrate in the sweep pattern. 
     
     
         14 . The method of  claim 11 , wherein the substrate is movable in a sweep pattern across the first surface and applying the second pressure further comprises applying a variable pressure to the feature side of the substrate as the substrate is moved in the sweep pattern. 
     
     
         15 . The method of  claim 11 , wherein applying the second pressure further comprises applying a first sub-pressure to a first zone of the second surface of the polishing pad and a second sub-pressure to a second zone of the second surface of the polishing pad. 
     
     
         16 . A method for polishing a substrate, comprising:
 retaining a substrate in a carrier head adapted to move the substrate relative to a polishing pad, the carrier head having a first pressure applicator that is movable with the substrate, the first pressure applicator having one or more pressure zones that apply pressure to a first side of the substrate;   moving the substrate in a sweep pattern relative to a first side of the polishing pad; and   delivering a counter pressure to a second side of the substrate from a second pressure applicator as the substrate moves in the sweep pattern, the second pressure applicator disposed on a second side of the polishing pad and being movable relative to the substrate.   
     
     
         17 . The method of  claim 16 , wherein the second pressure applicator is adapted to form a fluid bearing between the second pressure applicator and the second side of the polishing pad. 
     
     
         18 . The method of  claim 17 , wherein the fluid bearing comprises an air bearing. 
     
     
         19 . The method of  claim 16 , wherein second pressure applicator comprises one or more pressure sources adapted to provide independent pressure to one or more pressure zones within the second pressure applicator. 
     
     
         20 . The method of  claim 19 , wherein the second pressure applicator comprises one or more concentric rings in contact with a second side of the polishing pad.