Spectral Analyses of the Impact of Nanotopography of Silicon Wafers on Oxide Chemical Mechanical Polishing

The purpose of this study is to investigate quantitatively how the height change of silicon wafer surfaces (nanotopography) impacts on the variation of removal rate during oxide chemical mechanical polishing (CMP). We have analyzed the spatial power spectral densities (PSD) of both nanotopography and thickness variation of oxide film after CMP. We defined a transfer function as the ratio of PSD for the oxide film thickness variation to that for nanotopography. The transfer function decreased with increase of the wavelength and this result quantitatively indicates that longer wavelength of nanotopography influence relatively less on the oxide thickness variation after CMP.