Patent ID: 7121934

Claim:
A carrier head of a chemical mechanical polishing apparatus, the carrier head comprising: a carrier housing driven by a carrier driving shaft; a holder housing installed coaxially with the carrier housing at a lower portion of the carrier housing and having a ring shape; a wafer support assembly vertically moving up and down along an inner wall of the holder housing; and a mounting chamber for allowing the wafer support assembly to slidably move up and down along the inner wall of the holder housing formed at a center of the holder housing, wherein the wafer support assembly includes an adjustment chamber, to which pressure is applied, and a membrane having a second hole at a center thereof, pressurized fluid is introduced into the adjustment chamber through the pressure pipe while a polishing process is being carried out so that the membrane is outwardly expanded, thereby applies pressure substantially evenly to a rear surface of a wafer, a suction part being formed at a center of the membrane such that the suction part is connected to a vacuum pipe by passing through the adjustment chamber, and a retainer ring being installed at an outer portion of the wafer support assembly in such a manner that the retainer ring vertically moves, wherein the wafer support assembly includes a holder shaft inserted into a first hole formed at a center of the holder housing and vertically movable in the first hole, a membrane upper holder mounted at a lower portion of the holder shaft, and a membrane lower holder positioned at a lower portion of the membrane upper holder, wherein the membrane wraps a lower surface of the membrane lower holder; wherein an outer peripheral end of the membrane is clamped between and by an outer end of the membrane upper holder and an outer end of the membrane lower holder so as to provide a mounting surface for the wafer; and wherein an inner peripheral end of the membrane is fixed to a lower end of a vacuum pipe through the holder shaft at a center upper end of the adjustment chamber.