Fabrication of replacement metal gate devices

摘要

A polishing method includes polishing, in a first polish, a wafer to remove overburden and planarize a top layer leaving a portion remaining on an underlying layer. A second polishing step includes two phases. In a first phase, the top layer is removed and the underlying layer is exposed, with a top layer to underlying layer selectivity of between about 1:1 to about 2:1 to provide a planar topography. In a second phase, residual portions of the top layer are removed from a top of the underlying layer to ensure complete exposure of an underlying layer surface.