Polishing pad with endpoint window

Abstract

A polishing pad for chemical mechanical polishing comprising a porous polishing layer having a top polishing surface, a sub-pad located opposite from the top polishing surface, the sub-pad having a bottom sub-pad surface, and a window for transmitting a signal wave through the polishing pad to a substrate to be polished and back through the polishing pad for endpoint detection, the window having a top window surface, a bottom window surface, and side edges, wherein the top window surface is recessed from the top polishing surface, the bottom window surface is substantially coplanar with the bottom sub-pad surface, the window extending from the bottom sub-pad surface to the top window surface and the side edges are in contact with the polishing material and the sub-pad material and wherein the window is non-porous.

Dependencies are inferred from the claim text.