Wafer polisher head adapted for easy removal of wafers

A device for use with a polishing apparatus having a polishing head and a polishing surface for polishing one face of a pair of opposed faces of a wafer, said one wafer face being oriented during polishing generally parallel to and in substantial contact with said polishing surface, said polishing head being movable to relocate said polishing head toward said polishing surface when polishing said wafer and away from said polishing surface when said polishing is terminated, said device comprising the combination of:

• a carrier for a wafer adapted to be mounted to said polishing head of said polishing apparatus so as to permit an attachment surface defined by said carrier to tilt relative to said polishing surface, which attachment surface is configured to mate with at least two regions on the other one of said pair of opposed faces of said wafer each located on only one side of an imaginary line bisecting said one face of said wafer not bisecting one of said two regions;
• first means for developing a first adhesive force between said attachment surface and a first one of said wafer regions;
• and
• second means for developing a second adhesive force between said attachment surface and a second one of said wafer regions, said first adhesive force being a higher magnitude force than said second adhesive force developed between said attachment surface and said second region so as to cause differential adhesion between said wafer face and said attachment surface proximate said first and second wafer regions wherein said first region is held more forcefully to said attachment surface than said second region is held to said attachment surface;
• said second means for developing a second adhesive force between said attachment surface and said second wafer region includes directing means for selectively directing a vacuum provided by a vacuum source which otherwise might be applied to both of said regions to said second region to the exclusion of the first region;
• said differential adhesive force on two regions of another face results in facilitating preferential separation of the other one of said faces to be polished from said polishing surface proximate said first region on said opposed face when said polishing head is moved away from said polishing by adhering said first region of said wafer with greater force.

A device for use with a polishing apparatus having a polishing head and a polishing surface for polishing one face of a pair of opposed faces of a wafer, said one wafer face being oriented during polishing generally parallel to and in substantial contact with said polishing surface, said polishing head being movable to relocate said polishing head toward said polishing surface when polishing said wafer and away from said polishing surface when said polishing is terminated, said device comprising the combination of:

• a flexible fluid impermeable membrane;
• a carrier for a wafer coupled to said polishing head by said flexible membrane and defining an attachment surface configured to mate with a first region of said wafer on the other one of said pair of opposed faces of said wafer;
• means for forming a first pressure differential between two volumes on opposite sides of said flexible membrane to cause said carrier to exert a polishing force against said polishing surface during polishing in proportion to said pressure differential;
• and
• means for forming a second pressure differential between a volume adjacent to a region of said attachment surface and another volume and for directing an adhesive force caused by said second pressure differential to said wafer in proportion to said second pressure differential;
• whereby a polishing pressure may be exerted by said means for forming a first pressure differential and separation of said wafer face from said polishing surface is facilitated by said means for forming a second pressure differential.

A method for releasing a second face of a wafer having two opposed faces from attachment to a wafer polishing surface while maintaining attachment of the first opposed wafer face to a wafer attachment surface on a polishing head, said method comprising the steps of:

• developing a first adhesive force between said attachment surface and one region of said first wafer face;
• developing a second adhesive force between said attachment surface and a second wafer region of said first wafer face which is different than the force developed between said attachment surface and said first region so as to cause a differential in adhesive force between said first and second regions of said first wafer face and said attachment surface so that said first region is held more forcefully to said attachment surface than said second region, said first and second regions being located only one side of an imaginary line bisecting said one face of said wafer not bisecting one of said two regions;
• said differential in adhesive force facilitating preferential separation of said second wafer face from said polishing surface proximate the region having the larger adhesive force when said polishing head is moved away from said polishing surface;
• and
• moving said attachment surface in a manner that causes said attachment surface to be separated from said polishing surface so that separation and release of said second wafer face from said polishing surface is facilitated.