The present invention relates to an article for altering a surface of a
workpiece, or a polishing pad having a window. In particular, the
polishing pad includes a polyurethane urea material wherein the
polyurethane urea material contains cells which are at least partially
filled with gas. The polyurethane urea material can be prepared by
combining polyisocyanate and/or polyurethane prepolymer,
hydroxyl-containing material, amine-containing material and blowing
agent. The polishing pad according to the present invention is useful for
polishing articles, and is especially useful for chemical mechanical
polishing or planarization of microelectronic and optical electronic
devices such as but not limited to semiconductor wafers. The window of
the polishing pad is at least partially transparent and thus, can be
particularly useful with polishing or planarizing tools that are equipped
with through-the-platen wafer metrology.