Patent ID: 6579151
Filing Date: 2003-06-17
Classification: B24B

Abstract:
A polishing head for holding a wafer therein during a polishing process comprising:a carrier head having a recessed peripheral edge portion adapted for engaging top surfaces of at least three piezoelectric actuator/sensors spaced-apart equally along said peripheral edge portion, and a non-recessed center portion having a bottom surface for intimately engaging a wafer; a retaining ring surrounding said wafer having a bottom surface in the same horizontal plane of an active surface of said wafer, said retaining ring having a top surface adapted for engaging bottom surfaces of said at least three piezoelectric actuator/sensors; at least three piezoelectric actuator/sensors mounted in-between said recessed peripheral edge portion of said carrier head and said top surface of said retaining ring; and a process controller for receiving force signals from said at least three piezoelectric actuator/sensors, comparing the force signals to pre-stored data, and delivering an electrical current to said at least three piezoelectric actuator/sensors to increase/decrease forces exerted on said retaining ring.