Retaining ring for cmp

Abstract

A retaining ring includes: a generally annular body having an inner surface to constrain a substrate and a bottom surface, the bottom surface having multiple channels extending from an outer surface to the inner surface. Each channel of the multiple channels includes an inner channel and outer channel connected by a reservoir channel, the reservoir channel having an annular shape within the bottom surface. The outer channel has two opposing sidewalls and both opposing sidewalls of the outer channel have an inflection point.

What is claimed is: 
     
         1 . A retaining ring, comprising:
 a generally annular body having an inner surface to constrain a substrate and a bottom surface, the bottom surface having a plurality of channels extending from an outer surface to the inner surface,   wherein each channel of the plurality of channels comprises an inner channel and outer channel connected by a reservoir channel, the reservoir channel having an annular shape within the bottom surface, and   wherein the outer channel has two opposing sidewalls and both opposing sidewalls of the outer channel have an inflection point.   
     
     
         2 . The retaining ring of  claim 1 , wherein the inner channel has a first orientation, the outer channel has a second orientation, and the first and second orientations are different. 
     
     
         3 . The retaining ring of  claim 1 , wherein the outer channel has a first width where the outer channel meets the reservoir channel, a second width where the outer channel meets an outer diameter surface of the retaining ring, and the second width is greater than the first width. 
     
     
         4 . The retaining ring of  claim 3 , wherein the first width is in a range of 10-15 mm, and the second width is in a range of 20-30 mm. 
     
     
         5 . The retaining ring of  claim 3 , wherein the outer channel has a third width in an intermediate portion of the outer channel that is less than both the first and second widths. 
     
     
         6 . The retaining ring of  claim 5 , wherein the third width is in a range of 5-10 mm. 
     
     
         7 . The retaining ring of  claim 5 , wherein sidewalls of the outer channel are S-shaped. 
     
     
         8 . The retaining ring of  claim 1 , wherein intermediate portions of sidewalls of the inner channel are substantially parallel. 
     
     
         9 . The retaining ring of  claim 8 , wherein a width between the intermediate portions of the sidewalls of the inner channel is in a range of 2-5 mm. 
     
     
         10 . The retaining ring of  claim 8 , wherein ends of the sidewalls of the inner channels flare where the inner channel meets an inner diameter surface of the retaining ring and the reservoir channel. 
     
     
         11 . The retaining ring of  claim 10 , wherein a width between the ends of the sidewalls of the inner channels is in a range of 2-5 mm. 
     
     
         12 . The retaining ring of  claim 1 , wherein a length of the inner channel is in a range of 10-20 millimeters. 
     
     
         13 . The retaining ring of  claim 1 , wherein the bottom surface of the annular body defines a contact area comprising inner and outer islands, the inner and outer islands separated by the inner and outer channels, respectively, and
 wherein a first area of the contact area is a sum of areas of the inner and outer islands, a second area is an annular area of the generally annular body, and a ratio of the first area to the second area is about 50% or less.   
     
     
         14 . The retaining ring of  claim 1 , wherein the plurality of channels are spaced uniformly around the annular body. 
     
     
         15 . The retaining ring of  claim 14 , wherein there are eight to thirty channels. 
     
     
         16 . The retaining ring of  claim 1 , wherein each channel of the plurality of channels comprises a leading edge and a trailing edge, and wherein the leading and trailing edges are not symmetric across a centerline of the channel. 
     
     
         17 . The retaining ring of  claim 1 , wherein sidewalls of the inner channel are oriented at an angle of about 30-60° relative to a radial direction. 
     
     
         18 . The retaining ring of  claim 1 , wherein a width of the annular shape of the reservoir channel is less than 2 mm. 
     
     
         19 . A carrier head, comprising:
 a base;   a flexible membrane coupled to the base, the flexible membrane having a mounting surface for a substrate; and   the retaining ring of  claim 1  coupled to the base.   
     
     
         20 . A retaining ring, comprising:
 a generally annular body having an inner surface to constrain a substrate and a bottom surface, the bottom surface having a plurality of channels extending from an outer surface to the inner surface,   wherein each channel of the plurality of channels comprises an S-shaped channel extending from an outer edge of the bottom surface to a reservoir channel, the reservoir channel extending in an annular shape around the bottom surface and connected to an inner edge of the bottom surface.