US Patent 7169017 Polishing pad having a window with reduced surface roughness

The present invention provides a polishing pad for performing chemical mechanical planarization of semiconductor substrates. The polishing pad comprises a polishing pad body having an aperture formed therein and a window fixed in the aperture for performing in-situ optical measurements of the substrate. The window has a lower surface capable of transmitting light incident thereon. The lower surface has been treated by laser ablation to remove surface roughness present on the lower surface.