Patent ID: 7156726

Claim:
A polishing Apparatus comprising: a polishing platen having a first central region and a first peripheral region, the first central region having a first front surface and the first peripheral region having a second front surface, wherein the polishing platen is uniformly tapered from said first central region to said first peripheral region; a polishing pad overlying the polishing platen; an under pad overlying the polishing platen and underlying the polishing pad, wherein both the polishing pad and the under pad having a second central region and a second peripheral region formed of a single material having a standard compression characteristic throughout, the second central region having a first front surface and the second peripheral region having a second front surface, wherein at least a portion of the second peripheral region having the second front surface lies below the second central region having the first front surface, wherein at least a portion of said second front surface of said second peripheral region of the polishing pad and the underlying pad overlies the uniformly tapered portion of said second front surface of said first peripheral region of said polishing platen, said tapered region designed such that when said first front surface of said second central region contacts a substrate surface, said second front surface of said second peripheral region is not initially in contact with said substrate surface thereby providing a uniform center to edge polishing characteristic; and a carrier overlying the polishing pad, wherein said carrier rotates in a direction opposite to said polishing pad and said under pad.