Patent ID: 7156946
Filing Date: 2007-01-02
Classification: B24B

Abstract:
1. A wafer carrier for holding a wafer against a polishing pad in a CMP process, said wafer carrier characterized by a wafer carrier housing adapted to be rotationally fixed to a drive spindle, and a pressure plate disposed coaxially with the carrier housing, said pressure plate adapted to contact the backside of a wafer during polishing, and maintain the front side of the wafer in contact with the polishing pad during CMP, said pressure plate being rotationally fixed to the carrier housing, said wafer carrier further comprising: a pivoting mechanism comprising: a first ring having a plurality of ball transfer units affixed thereto, each of said ball transfer units comprising a load ball rotatably disposed within the ball transfer unit; a second ring, said second ring having bearing surfaces adapted to contact the load balls of the ball transfer units, said second ring disposed coaxially with the first ring with the bearing surfaces disposed in apposition to the load balls; said pivoting mechanism disposed between the carrier housing and the pressure plate, and secured to the carrier housing and pressure plate so as to permit pivoting motion of the pressure plate relative to the carrier housing; wherein the ball transfer units are disposed within housings protruding from the first ring toward the second ring, said housings orienting the load balls in apposition to the bearing surfaces of the second ring, and the second ring comprises a plurality of wedges extending toward the first ring, each of said wedges establishing the bearing surfaces in apposition to the load balls.