We discuss the optical interferometry technique, including a description of the parameters necessary to compare pad samples. Flat, mesa-like structures formed on the pad during the first 5 min polish when conditioning was not used. The data from the optical interferometer indicated that the surface topography did not change with subsequent polishing, even though the thermal oxide removal rate continued to decrease. We found conditioning roughened the pad surface. Rougher pad surfaces removed more oxide during a single 5 min polish than comparatively smooth pad surfaces.
Data indicates that conditioning increases and stabilizes pad surface roughness.
In situ and ex situ conditioning have been compared. In situ conditioning has proven to yield higher removal rates with improved, within wafer uniformities. Some of the factors contributing to the pad deterioration such as the conditioning tool down force, tool speed, and the type of solubilizing ions in the slurry is examined. The dependence on diamond particle sizes, nickel plated on to the conditioning discs, is discussed. The extent of pad wear caused by all of the above factors has been quantitatively determined and presented.