A window polishing pad having a reduced stress pad window formed therein
for performing optical end point detection are provided, wherein the
window polishing pad comprises a pad window and a pressure relief
channel, wherein the pressure relief channel extends to an outer
periphery of the window polishing pad from a cavity formed behind the pad
window when the window polishing pad is interfaced with a platen and
wherein a membrane is provided over at least one of an inlet and an
outlet of the pressure relief channel. Also disclosed are methods of
making and of using the window polishing pads to polish a semiconductor
wafer.