Electrolyte retaining on a rotating platen by directional air flow

Abstract

A method and apparatus for retaining electrolyte on a rotating platen using directional air flow is provided. In one embodiment, an apparatus for processing a substrate is provided. The apparatus includes a platen assembly having a surface for supporting a processing pad and disposed on a stationary base so that the platen assembly may rotate relative to the base; and an air knife coupled to the base and extended over a portion of the surface, the air knife operable to deliver a stream of air toward the pad to divert at least a portion of a fluid disposed on the pad toward a center of the pad.

1 . An apparatus for processing a substrate, comprising:
 a platen assembly having a surface for supporting a processing pad and disposed on a stationary base so that the platen assembly may rotate relative to the base; and   an air knife coupled to the base and extended over a portion of the surface, the air knife operable to deliver a stream of air toward the pad to divert at least a portion of a fluid disposed on the pad toward a center of the pad.   
     
     
         2 . The apparatus of  claim 1 , wherein:
 a first end of the air knife is disposed proximate an edge of the surface,   a longitudinal axis of the air knife extends from the edge and toward the center of the surface, and   the longitudinal axis of the air knife is inclined relative to a radial centerline, through the first end, of the surface by an angle.   
     
     
         3 . The apparatus of  claim 2 , wherein the angle is greater than zero and less than or equal to forty-five degrees. 
     
     
         4 . The apparatus of  claim 1 , wherein a length of the air knife ranges from about one-fourth of a radius of the surface to about equal to the radius of the surface. 
     
     
         5 . The apparatus of  claim 1 , wherein the air knife comprises an elongated plenum having a longitudinal opening configured to delver the stream of air toward the pad at a high velocity. 
     
     
         6 . The apparatus of  claim 1 , further comprising the pad disposed on the platen assembly and the fluid disposed on the pad, wherein the pad is made from an electrically conductive material and the fluid is an electrolyte. 
     
     
         7 . A method of processing a substrate, comprising:
 providing a platen assembly, comprising a polishing pad disposed thereon and a fluid disposed on the polishing pad;   providing an air knife disposed over the pad;   rotating the platen assembly; and   operating the air knife to deliver a stream of air toward the pad, wherein the stream of air will divert at least at least a portion of the fluid toward the center of the pad.   
     
     
         8 . The method of  claim 7 , wherein:
 a first end of the air knife is disposed proximate an edge of the pad,   a longitudinal axis of the air knife extends from the edge and toward the center of the pad, and   the longitudinal axis of the air knife is inclined relative to a radial centerline of the pad by an angle.   
     
     
         9 . The method of  claim 8 , wherein the angle is greater than zero and less than or equal to forty-five degrees. 
     
     
         10 . The method of  claim 7 , wherein a length of the air knife ranges from about one-fourth of a radius of the pad to about equal to the radius of the pad. 
     
     
         11 . The method of  claim 7 , further comprising disposing a substrate on the pad, wherein the substrate is polished by the pad. 
     
     
         12 . The method of  claim 7 , wherein the air knife comprises an elongated plenum having a longitudinal opening configured to delver the stream of air toward the pad at a high velocity. 
     
     
         13 . The method of  claim 7 , wherein the pad is made from an electrically conductive material and the fluid is an electrolyte. 
     
     
         14 . The method of  claim 13 , further comprising disposing a substrate on the pad and establishing an electrical potential between the substrate and the pad, wherein the substrate is polished by the pad and the electrical potential. 
     
     
         15 . The method of  claim 7 , wherein the stream of air will divert substantially all of the fluid toward the center of the pad.