POLISHING APPARATUS THAT PROVIDES A WINDOW

摘要

A polishing pad apparatus includes, a polishing pad (2), an optically transmissive window (6) framed by an opening (5) through the polishing pad (2), the window (6) being part of an underlay (8), and the underlay (8) having a perimeter (8a) that extends susbtantially beyond the perimeter (6b) of the window (6) to form a fluid impermeable layer that isolates a rear surface (6a) of the window (6) from obstruction by polishing fluid.