Patent ID: 7364496

Claim:
A polishing head comprising: a base structure having a lower surface, said base structure being configured to include at least one recess region on said lower surface; an outer flexible membrane positioned below said base structure, said outer flexible membrane and said base structure defining a chamber below said base structure; a first fluid channel operatively connected to said chamber to apply suction to at least a portion of said chamber, said suction causing said outer flexible membrane to conform to said at least one recess region of said base structure such that at least one depression is formed on a bottom surface of said outer flexible membrane; and a second fluid channel configured to extend through said outer flexible membrane such that an opening of said second fluid channel is positioned in said at least one depression when said suction is applied to said chamber, said second fluid channel being used to apply another suction to said at least one depression to hold a semiconductor wafer onto said outer flexible membrane.