Apparatus and method for planar end-point detection during chemical-mechanical polishing

摘要

A chemical-mechanical polishing apparatus includes a slurry-wetted polishing pad attached to a substantially planar surface of a platen. A wafer carrier is positioned in close proximity to the platen, and it has a substantially planar surface to which one side of a semiconductor wafer is removably attachable so that an opposing side of the semiconductor wafer is disposed against the polishing pad. An actuator imparts a translational motion to the platen so that the polishing pad moves relative to and in polishing contact with the semiconductor wafer. A sensor detects a change in the imparted translational motion corresponding to a change in the coefficient of friction between the polishing pad and the opposing side of the semiconductor wafer indicative of a planar end point on the opposing side of the semiconductor wafer. The sensor preferably includes a laser and a laser detector using a laser reflection or laser interferometric method to detect the change in the imparted translational motion. Also, the apparatus preferably includes a controller coupled to the sensor and the actuator to adjust the actuator in response to the sensor detecting a change in the imparted translational motion.