System and method for CMP having multi-pressure zone loading for improved edge and annular zone material removal control

Abstract

In one aspect, the invention provides a method for planarizing a circular disc-type semiconductor wafer or other substrate. The method includes the steps of pressing a retaining ring surrounding the wafer against a polishing pad at a first pressure; pressing a first peripheral edge portion of the wafer against the polishing pad with a second pressure; and pressing a second portion of the wafer interior to the peripheral edge portion against the polishing pad with a third pressure. The second pressure may be provided through a mechanical member in contact with the peripheral edge portion; and the second pressure may be a pneumatic pressure against a backside surface of the wafer. Desirably, the pneumatic pressure is exerted through a resilient membrane, or is exerted by gas pressing directly against at least a portion of the wafer backside surface. A carrier or subcarrier for a CMP apparatus that includes: a plate having an outer surface; a first pressure chamber for exerting a force to urge the plate in a predetermined direction; a spacer coupled to a peripheral outer edge of the plate; a membrane coupled to the plate via the spacer and separated from the plate by a thickness of the spacer; and a second pressure chamber defined between the membrane and the plate surface for exerting a second force to urge the membrane in a third predetermined direction. Substrate, such as a semiconductor wafer, processed or fabricated according to the invention.

1 . A substrate subcarrier for polishing a substrate against a polishing pad in a chemical mechanical polishing (CMP) tool, said subcarrier comprising: 
 a substrate receiving portion to receive said substrate;    a vacuum line drawing a vacuum for holding said substrate on said substrate receiving portion; and    a reservoir provided in said subcarrier, which collects any polishing slurry or debris that may be sucked or pulled into said vacuum line.    
     
     
         2 . A substrate subcarrier as in  claim 1 , wherein a reservoir comprises a slope and an opening for facilitating drainage of the slurry or debris out of said subcarrier.  
     
     
         3 . A substrate subcarrier as in  claim 2 , wherein fluid is injected into said reservoir for cleaning inside of said reservoir.  
     
     
         4 . A method for carrying a substrate during the polishing of the substrate against a polishing pad in a CMP tool, said method comprising: 
 receiving a substrate at a subcarrier receiving portion;    holding said substrate on said substrate receiving portion with a vacuum pressure; and    collecting any polishing slurry or debris that may be sucked or pulled into said vacuum line into a reservoir provided in said subcarrier.    
     
     
         5 . A method  claim 4 , wherein the reservoir comprises a slope and an opening for facilitating drainage of the slurry or debris out of said subcarrier.  
     
     
         6 . A method as in  claim 5 , wherein fluid is injected into said reservoir for cleaning inside of said reservoir.  
     
     
         7 . A polishing apparatus for polishing a surface of a substrate, comprising: 
 a rotatable polishing pad; and    a substrate subcarrier including: 
 a substrate receiving portion to receive the substrate and to position the substrate against the polishing pad;  
 a flexible member connected to said subcarrier such that the bottom surface of said flexible member is capable of contacting said substrate when in operation; and  
 an annular member mechanically coupling a peripheral portion of said flexible member to said substrate subcarrier such that a first force applied to said annular member during operation results in a first pressure exerted against said substrate in contact with said peripheral portion of said flexible member.  
   
     
     
         8 . The polishing apparatus of  claim 7 , wherein said flexible member comprises a membrane.  
     
     
         9 . The polishing apparatus of  claim 8 , wherein said annular member comprises a thickened portion of said membrane.  
     
     
         10 . A substrate subcarrier for polishing a substrate against a polishing pad in a CMP tool, said subcarrier comprising: 
 a substrate receiving portion to receive said substrate;    a flexible member connected to said subcarrier such that the bottom surface of said flexible member is capable of contacting said substrate when in operation; and    an annular member mechanically coupling a peripheral portion of said flexible member to said substrate subcarrier such that a first force applied to said subcarrier during operation results in a first pressure exerted against said substrate in contact with said peripheral portion of said flexible member; and    a second pressing member applying a second pressure to a central portion of said flexible member, thereby applying a second pressure to said substrate when in operation.    
     
     
         11 . A substrate subcarrier as in  claim 10 , wherein said flexible member comprises a membrane and said annular member comprises a thickened portion of said membrane.  
     
     
         12 . The subcarrier of  claim 11 , wherein said flexible member is a membrane and said membrane is decoupled from said wafer subcarrier in at least one location by a chamber, wherein said chamber is capable of being pressurized to exert a pneumatic pressure on said substrate during operation in a location contacting said decoupled portion of said flexible member.