Partial Contact Wafer Retaining Ring Apparatus

Abstract

The partial contact wafer retaining ring apparatus is disclosed. For example, one disclosed embodiment provides a wafer retaining ring comprising a ring for retaining the wafer, the ring having an inner diameter surface configured to restrict lateral wafer motion, and at least one interface surface configured to interface with a polishing surface. The interface surface comprises a recessed section adjacent to the ring inner diameter, configured to preclude contact between the recessed section and the polishing surface.

1 . An apparatus for retaining a wafer during polishing, comprising:
 a ring for retaining the wafer, said ring having an inner diameter surface configured to restrict lateral wafer motion, and at least one interface surface configured to interface with a polishing surface, said interface surface having a recessed section adjacent to the ring inner diameter, configured to preclude contact between the recessed section and the polishing surface.   
     
     
         2 . The apparatus of  claim 1 , wherein the recessed section is configured to preclude contact between the wafer and any portion of the polishing surface that also contacts said interface surface during polishing. 
     
     
         3 . The apparatus of  claim 1 , wherein the recessed section is configured to preclude contact between the wafer and localized surface deformations on the polishing surface due to contact with said interface surface during polishing. 
     
     
         4 . The apparatus of  claim 1 , wherein the recessed section comprises a constant diametric width. 
     
     
         5 . The apparatus of  claim 1 , wherein the recessed section comprises a varying diametric width. 
     
     
         6 . The apparatus of  claim 1 , wherein the recessed section comprises a single continuous surface. 
     
     
         7 . The apparatus of  claim 1  wherein the recessed section comprises one or more discrete surfaces. 
     
     
         8 . The apparatus of  claim 1 , wherein the inner diameter surface and the remainder of the apparatus comprise different materials. 
     
     
         9 . The apparatus of  claim 1 , wherein the inner diameter surface and the interface surface comprise different materials. 
     
     
         10 . The apparatus of  claim 1 , wherein the inner diameter surface comprises a removable piece. 
     
     
         11 . The apparatus of  claim 1 , wherein the inner diameter surface comprises a single continuous surface. 
     
     
         12 . The apparatus of  claim 1 , wherein the inner diameter surface comprises one or more discrete surfaces. 
     
     
         13 . The apparatus of  claim 1 , wherein the inner diameter surface is perpendicular to the interface surface. 
     
     
         14 . A system for polishing wafers, comprising:
 a polishing surface;   a ring for retaining the wafer, said ring having an inner diameter surface for restricting lateral wafer motion, and at least one interface surface configured to interface with the polishing surface, said interface surface having one or more recessed sections adjacent to the ring inner diameter, configured to preclude contact between the recessed surface and the polishing surface; and   a clamping device configured to hold the wafer and retaining ring against the polishing surface.   
     
     
         15 . The system of  claim 14 , wherein the recessed section of the retaining ring is configured to preclude contact between the wafer and any portion of the polishing surface that has also contacted said apparatus during polishing. 
     
     
         16 . The system of  claim 14 , wherein the recessed section of the retaining ring is configured to preclude contact between the wafer and localized surface deformations on the polishing surface due to contact with said apparatus during polishing. 
     
     
         17 . The system of  claim 14 , wherein the inner diameter surface of the retaining ring comprises a removable piece. 
     
     
         18 . A method for polishing wafers, comprising:
 placing a wafer on a polishing surface;   restricting lateral motion of the wafer with a retaining device;   clamping the wafer and retaining device against the polishing surface; and   polishing the wafer such that the wafer does not contact any area of the polishing surface that has also contacted the retaining device.   
     
     
         19 . The method of  claim 18 , further comprising polishing the wafer such that localized surface deformations on the polishing surface due to contact with the retaining device do not contact any part of the wafer. 
     
     
         20 . The method of  claim 18 , wherein restricting lateral motion of the wafer with a retaining device comprises placing the wafer within a ring having an inner diameter surface for restricting lateral wafer motion, and at least one surface configured to interface with the polishing surface, said interface surface having one or more recessed sections adjacent to the ring inner diameter, configured to preclude contact between the recessed surface and the polishing surface. 
     
     
         21 . The method of  claim 18 , further comprising removing and replacing the inner diameter surface of the retaining ring.