Polishing head assemblies for polishing semiconductor wafers

Abstract

Polishing head assemblies for single side polishing of silicon wafers. The polishing head assemblies may include a template having a step at the edge of the template and/or a template support disposed between the template and the floor of the cap of the polishing head assembly. Some polishing head assemblies may include a cap having a thinner floor.

What is claimed is: 
     
         1 . A polishing head assembly for polishing a semiconductor wafer, the polishing head assembly comprising:
 a polishing head;   a cap connected to the polishing head, the cap and polishing head forming a chamber therebetween, the cap comprising a floor; and   a template for securing the semiconductor wafer to the polishing head assembly, the template being connected to the floor, the template having a central axis, a circumferential edge, and a radius, the radius extending from the central axis to the circumferential edge, the template having a thickness, the thickness of the template varying along the radius of the template.   
     
     
         2 . The polishing head assembly as set forth in  claim 1  wherein the thickness of the template increases from its central axis to the circumferential edge of the template. 
     
     
         3 . The polishing head assembly as set forth in  claim 2  wherein the thickness increases in a step change in thickness, the step change in thickness being disposed between the central axis and the circumferential edge of the template. 
     
     
         4 . The polishing head assembly as set forth in  claim 2  wherein the thickness of the template changes continuously along at least a portion of the radius of the template. 
     
     
         5 . The polishing head as set forth in  claim 1  wherein the floor has a central axis, a circumferential edge, and a radius, the radius extending from the central axis to the circumferential edge, the floor having a thickness, the thickness of the floor varying along the radius of the floor. 
     
     
         6 . The polishing head as set forth in  claim 1  wherein the thickness of the template decreases from the central axis to the circumferential edge of the template. 
     
     
         7 . The polishing head as set forth in  claim 1  wherein the thickness of the template increases from the central axis to the circumferential edge of the template, the template comprising a step at which the thickness of the template increases, the floor comprising a floor recess, the step being disposed in the floor recess. 
     
     
         8 . The polishing head as set forth in  claim 7  wherein the step extends to the circumferential edge of the template. 
     
     
         9 . The polishing head as set forth in  claim 7  wherein the step has a width, the width being at least 5% of the radius of the template. 
     
     
         10 . The polishing head as set forth in  claim 6  wherein the thickness of the template increases by at least 25% at the step. 
     
     
         11 . A polishing head assembly for polishing a semiconductor wafer, the polishing head assembly comprising:
 a polishing head;   a cap connected to the polishing head, the cap and polishing head forming a chamber therebetween, the cap comprising a floor;   a template for securing the semiconductor wafer to the polishing head assembly, the template having a central axis, a circumferential edge, and a radius, the radius extending from the central axis to the circumferential edge; and   a template support disposed between the cap and template, the template support being connected to the floor.   
     
     
         12 . The polishing head assembly as set forth in  claim 11  wherein the template has a radius and the template support has a radius, the radius of the template support being less than the radius of the template. 
     
     
         13 . The polishing head assembly as set forth in  claim 12  wherein the radius of the template support is at least 1% less than the radius of the template. 
     
     
         14 . The polishing head assembly as set forth in  claim 11  wherein the template and template support are made from different materials. 
     
     
         15 . The polishing head assembly as set forth in  claim 11  wherein the floor comprises a floor recess, the template support being disposed in the floor recess. 
     
     
         16 . The polishing head assembly as set forth in  claim 15  wherein the template comprises a step at which the thickness of the template increases, the floor comprising a second floor recess, the step being disposed in the second floor recess. 
     
     
         17 . The polishing head as set forth in  claim 16  wherein the step extends to the circumferential edge of the template. 
     
     
         18 . A polishing head assembly for polishing a semiconductor wafer, the polishing head assembly comprising:
 a polishing head;   a cap connected to the polishing head, the cap and polishing head forming a chamber therebetween, the cap comprising a floor, the floor being made of metal, the floor having a central axis, a circumferential edge, and a radius, the radius extending from the central axis to the circumferential edge, the floor having a thickness of at least 8 mm along the entire radius of the floor; and   a template for securing the semiconductor wafer to the polishing head assembly, the template being connected to the floor.   
     
     
         19 . The polishing had as set forth in  claim 18  wherein the thickness of the floor is from 8 mm to 15 mm. 
     
     
         20 . The polishing head as set forth in  claim 18  wherein the floor is made of aluminum or is made of stainless steel.