Patent ID: 8192248

Claim:
A wafer polishing apparatus comprising: a base; a turntable having a polishing pad thereon and mounted on the base for rotation of the turntable and polishing pad relative to the base about an axis perpendicular to the turntable and polishing pad, the polishing pad including a work surface engageable with a front surface of a wafer for polishing the front surface of the wafer; a drive mechanism mounted on the base for imparting rotational motion about an axis substantially parallel to the axis of the turntable; and a polishing head connected to the drive mechanism for driving rotation of the polishing head, the polishing head having a pressure plate adapted to hold the wafer for engaging the front surface of the wafer with the work surface of the polishing pad, the pressure plate comprising a support plate and an annular wall extending from the support plate, the support plate having a generally planar position and being selectively movable from the planar position to a convex position and to a concave position, wherein the support plate is deflectable at its center by about 50 micrometers, the annular wall has a thickness between 2 millimeters (0.079 inches) and about 3 millimeters (0.118 inches) and defining a hinge about which the support plate can deflect from the planar position to one of the convex and concave positions, the annular wall flexing outward in relation to the upwards deflection of the support plate to the concave position, the annular wall flexing inward in relation to the downwards deflection of the support plate to the convex position.