Chemical-mechanical polishing station with end-point monitoring device

Abstract

A chemical-mechanical polishing station for polishing wafers. The polishing station comprises a slurry supplier, a polishing pad capable of collecting the slurry, and a polishing head capable of rotating a wafer and lowering the wafer onto the polishing pad in contact with the polishing pad and the slurry during a polishing session. The polishing head further includes a retaining ring for positioning the wafer. The retaining ring houses a light-emitting device capable of shining a beam of light onto the slurry and a light sensor for picking up the beam of light reflected back from the slurry. The exact polishing end-point can be decided by analyzing signals obtained from the light sensor.