Wafer polishing head

摘要

A polishing head (10) for polishing a semiconductor wafer includes a housing (14), a wafer carrier (20) movably mounted to the housing (14), and a wafer retainer (22) movably mounted to the housing (14). The wafer carrier (20) forms a wafer supporting surface, and the wafer retainer (22) is shaped to retain a wafer in place on the wafer-supporting surface. A first fluid actuator (24,28) is coupled to the wafer carrier (20) to bias the wafer carrier (20) in a selected direction with respect to the housing (14), and a second fluid actuator (36,42) is coupled to the wafer retainer (22) to bias the wafer retainer (22) in a second selected direction with respect to the housing (14). First and second fluid conduits (30,44) are coupled to the first and second actuators, respectively, such that fluid pressures in the first and second actuators are separately and independently adjustable with respect to one another. Biasing forces on the retainer (22) can thereby be dynamically adjusted with respect to biasing forces on the carrier (20) during the polishing operation.