Wafer polishing apparatus and wafer manufacturing method

A wafer manufacturing method comprising the steps of;

• holding a wafer to be polished on a wafer holding head, wherein said wafer holding head is installed in a wafer polishing apparatus having a platen including a polishing pad bonded to a surface thereof, and a wafer holding head both for holding said wafer to be polished and for bringing a first surface of said wafer into contact with said polishing pad to polish said wafer by separately rotating said wafer holding head and said platen, wherein said wafer holding head includes:
• a head body made up of a top plate and a tubular peripheral wall provided under an outer periphery of said top plate;
• a diaphragm stretched inside said head body, wherein said diaphragm is perpendicular to a head axis;
• a pressure regulating mechanism for regulating a pressure of a fluid in a fluid chamber, wherein said fluid chamber is located between said diaphragm and said head body;
• a carrier fixed to said diaphragm, wherein together said carrier and said diaphragm are displaceable in a direction of said head axis, and wherein said carrier holds a second surface of said wafer to be polished;
• a retainer ring disposed between an inner surface of said tubular peripheral wall and an outer peripheral surface of said carrier in concentric relation, wherein said retainer ring is fixed to said diaphragm and together said retainer ring and said diaphragm are displaceable in said direction of said head axis so that said retainer ring is brought into contact with said polishing pad during polishing of said wafer;
• an annular thin plate disposed in contact with at least part of said diaphragm;
• and a fixing device for fixing said annular thin plate to said head body, wherein said annular thin plate extends from said head body along a surface of said diaphragm;
• and
• polishing said wafer while said wafer is pressed against said polishing pad to form a polished wafer.