Wafer level uniformity control in remote plasma film deposition

Abstract

An assembly for use in a process chamber for depositing a film on a wafer. The assembly includes a pedestal having a pedestal top surface extending from a central axis of the pedestal to an outer edge, the pedestal top surface having a plurality of wafer supports for supporting a wafer. A pedestal step having a step surface extending from a step inner diameter towards the outer edge of the pedestal. A focus ring rests on the step surface and having a mesa extending from an outer diameter of the focus ring to a mesa inner diameter. A shelf steps downwards from a mesa surface at the mesa inner diameter, and extends between the mesa inner diameter and an inner diameter of the focus ring. The shelf is configured to support at least a portion of a wafer bottom surface of the wafer at a process temperature.

What is claimed is: 
     
         1 . A pedestal assembly for use in a process chamber, comprising:
 a pedestal comprising a pedestal top surface that is horizontally-oriented along a first plane, the pedestal top surface having a plurality of wafer supports configured to support a wafer at a wafer support level above the pedestal top surface;   a raised annular rim that protrudes from the pedestal top surface and is disposed on an outer edge of the pedestal top surface, wherein the raised annular rim comprises a mesa surface that is horizontally-oriented along a second plane and that is elevated above the pedestal top surface, and wherein the raised annular rim and the pedestal top surface define a pocket configured to receive the wafer; and   a beveled surface that extends from the mesa surface to the pedestal top surface, wherein each of the plurality of wafer supports sits within a hole that opens up at the pedestal top surface and rests on a compliant spacer that sits at a bottom of the hole, wherein the compliant spacer is configured to prevent each of the wafer supports from breaking and/or for height modulation.   
     
     
         2 . The pedestal assembly of  claim 1 , wherein the beveled surface is angled with respect to the pedestal top surface at an angle less than 90 degrees. 
     
     
         3 . The pedestal assembly of  claim 1 , wherein the outer edge of the pedestal comprises a material selected from a group consisting of: Yttria, aluminum nitride, aluminum oxide, aluminum oxynitride, silicon carbide, and glass. 
     
     
         4 . The pedestal assembly of  claim 1 , wherein the mesa surface extends from an outer diameter of the pocket to a curved surface that joins the mesa surface to the outer edge of the pedestal, wherein the outer edge of the pedestal is vertically-oriented relative to the mesa surface. 
     
     
         5 . The pedestal assembly of  claim 1 , wherein an outer diameter of the pocket is configured to promote sealing of a wafer edge of the wafer to the pedestal. 
     
     
         6 . The pedestal assembly of  claim 5 , wherein the outer diameter of the pocket is approximately 11.968 inches. 
     
     
         7 . The pedestal assembly of  claim 1 , wherein an inner diameter of the raised annular rim is less than 11.968 inches. 
     
     
         8 . The pedestal assembly of  claim 1 , further comprising:
 a lift pin assembly comprising a plurality of lift pins that extend through a plurality of pedestal shafts disposed within the pedestal.   
     
     
         9 . The pedestal assembly of  claim 1 , wherein the beveled surface is angled with respect to the pedestal top surface at an angle of approximately 60 degrees. 
     
     
         10 . The pedestal assembly of  claim 1 , wherein a height of the pocket is configured to promote sealing of a wafer edge of the wafer to the pedestal. 
     
     
         11 . The pedestal assembly of  claim 1 , wherein a height of the pocket is approximately 0.35 inches. 
     
     
         12 . The pedestal assembly of  claim 1 , wherein the raised annular rim is configured to limit lateral movement of the wafer. 
     
     
         13 . A pedestal assembly for use in a process chamber, comprising:
 a pedestal comprising a pedestal top surface that is horizontally-oriented along a first plane, the pedestal top surface having a plurality of wafer supports configured to support a wafer at a wafer support level above the pedestal top surface;   a raised annular rim that protrudes from the pedestal top surface and is disposed on an outer edge of the pedestal top surface, wherein the raised annular rim comprises a mesa surface that is horizontally-oriented along a second plane and that is elevated above the pedestal top surface, and wherein the raised annular rim and the pedestal top surface define a pocket configured to receive the wafer; and   a beveled surface that extends from the mesa surface to the pedestal top surface, wherein the beveled surface is angled with respect to the pedestal top surface at an angle less than 90 degrees.   
     
     
         14 . The pedestal assembly of  claim 13 , wherein the outer edge of the pedestal comprises a material selected from a group consisting of: Yttria, aluminum nitride, aluminum oxide, aluminum oxynitride, silicon carbide, and glass. 
     
     
         15 . The pedestal assembly of  claim 13 , wherein the beveled surface is configured to contact a lower portion of an outer edge of the wafer to promote edge sealing of the wafer to the pedestal. 
     
     
         16 . The pedestal assembly of  claim 13 , wherein the beveled surface is angled with respect to the pedestal top surface at an angle of approximately 60 degrees or less.