Adhesive-less carriers for chemical mechanical polishing

Abstract

Embodiments of the disclosure relate to a system, apparatus and method for polishing thin substrates with high planarity. The apparatus comprises a chemical mechanical polishing head and a plate. The polishing head comprises a bottom surface, a retaining ring, a workpiece-receiving pocket defined between the bottom surface and the retaining ring, and at least one vacuum port adapted to provide a vacuum to the workpiece-receiving pocket through the bottom surface of the polishing head. The plate is disposed in the workpiece-receiving pocket such that the upper side of the plate faces the bottom surface of the polishing head and the lower side of the plate faces away from the bottom surface of the polishing head. The plate has a geometry or a material property configured to allow fluid to pass between the upper side and the lower side of the plate upon application of vacuum in the workpiece-receiving pocket.

What is claimed is: 
     
         1 . An apparatus for polishing a substrate, the apparatus comprising:
 a chemical mechanical polishing (CMP) head comprising:
 a bottom surface; 
 a retaining ring; 
 a workpiece-receiving pocket defined between the bottom surface and the retaining ring; and 
 at least one vacuum port adapted to provide a vacuum to the workpiece-receiving pocket through the bottom surface; and 
   a plate disposed in the workpiece-receiving pocket, an upper side of the plate facing the bottom surface of the polishing head and a lower side facing away from the bottom surface of the polishing head, the plate having a geometry or a material property configured to allow fluid to pass between the upper side and the lower side of the plate upon application of the vacuum in the workpiece-receiving pocket.   
     
     
         2 . The apparatus of  claim 1 , wherein the pressure drop between the upper side and the lower side of the plate is less than 50% at a nominal superficial velocity of between one and two meters per second. 
     
     
         3 . The apparatus of  claim 1 , wherein the plate has porosity between 30-70% and pores less than 200 microns in size. 
     
     
         4 . The apparatus of  claim 1 , wherein the plate has a plurality of holes fluidly coupling the upper side and the lower side of the plate. 
     
     
         5 . The apparatus of  claim 1 , wherein the plate has a diameter substantially similar to a 200 mm semiconductor substrate, 300 mm semiconductor substrate or a 450 mm semiconductor substrate. 
     
     
         6 . The apparatus of  claim 1 , wherein the plate is fabricated from at least one of a ceramic material, a conducting material and a semi-conducting material, the plate comprising a plurality of fine holes formed therethrough. 
     
     
         7 . The apparatus of  claim 1 , wherein the plate has a thickness of between 250 microns and 1000 microns. 
     
     
         8 . A chemical mechanical polishing (CMP) system comprising:
 a rotatable platen;   a chemical mechanical polishing (CMP) head positionable over the platen, the polishing head adapted to urge a substrate against a polishing pad disposed on the platen for polishing, the polishing head comprising:
 a bottom surface; 
 a retaining ring; 
 a workpiece-receiving pocket defined between the bottom surface and the retaining ring; and 
 at least one vacuum port adapted to provide a vacuum to the workpiece-receiving pocket through the bottom surface; 
   a plate positionable in the workpiece-receiving pocket, an upper side of the plate facing the bottom surface of the polishing head and a lower side facing away from the bottom surface of the polishing head, the plate having a geometry or a material property configured to allow fluid to pass between the upper side and the lower side of the plate upon application of a vacuum in the workpiece-receiving pocket; and   a carrier having an upper mounting surface and a lower mounting surface, the upper mounting surface configured to mate with the plate and the lower mounting surface configured secure a substrate, the carrier having a plurality of vacuum holes extending between the upper mounting surface and the lower mounting surface.   
     
     
         9 . The system of  claim 7 , wherein the carrier is fabricated from a ceramic material. 
     
     
         10 . The system of  claim 7 , wherein the carrier is positionable in the workpiece-receiving pocket below the plate. 
     
     
         11 . The system of  claim 7 , wherein the pressure drop between the upper side and the lower side of the plate is less than 50% at a nominal superficial velocity of between one and two meters per second. 
     
     
         12 . The system of  claim 7 , wherein the plate has porosity between 30-70% and pores less than 200 microns in size. 
     
     
         13 . The system of  claim 7 , wherein the plate is fabricated from from at least one of a ceramic material, a conducting material and a semi-conducting material, the plate comprising a plurality of fine holes formed therethrough. 
     
     
         14 . The apparatus of  claim 7 , wherein the plate and the carrier have a combined thickness of between 500 microns and 1500 microns. 
     
     
         15 . A method of polishing a substrate, the method comprising:
 vacuum chucking a substrate through a carrier to a chemical mechanical polishing (CMP) head by vacuum applied through a plate disposed between the head and the carrier; and   polishing the substrate chucked to the head on a polishing pad.   
     
     
         16 . The method of  claim 15  further comprising:
 electrostatically chucking the substrate to the carrier. 
 
     
     
         17 . The method of  claim 15 , wherein vacuum chucking further comprises:
 applying vacuum to the substrate through pores formed through the plate.   
     
     
         18 . The method of  claim 15  wherein vacuum chucking further comprises:
 applying vacuum to the substrate through the holes formed through the plate and the carrier. 
 
     
     
         19 . The method of  claim 15  further comprising:
 releasing the substrate and the carrier from the polishing head by removing the vacuum applied to the substrate while the plate remains in the polishing head. 
 
     
     
         20 . The method of  claim 15  further comprising:
 releasing the substrate and the carrier and plate from the polishing head by removing the vacuum.