Patent ID: 7273407

Claim:
A transparent polishing pad useful for polishing a substrate in a chemical mechanical polishing process using a polishing composition and an in-situ optical end-point detection apparatus, the polishing pad comprising: a polymeric matrix material having a first refractive index; a plurality of polymeric capsules having cavities embedded within and optically connected to the polymeric matrix material, the polymeric capsules comprising a polymeric shell having a diameter, a thickness and a second refractive index within 30% of the first refractive index of the polymeric matrix, a liquid core contained within the cavities and optically connected to the polymeric shell having a third refractive index within 30% of the first refractive index of the polymeric matrix, the liquid core being water with incidental impurities; and a polishing surface comprising the polymeric matrix material and a plurality of asperities defined by the cavities of the embedded polymeric capsules exposed at the polishing surface.