Polishing Pad Specifications for Achieving High Edge Surface Flatness (Effect of Existing Edge Roll Off on Generated Edge Surface Profile)

概要

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As the substrates of semiconductor devices, silicon wafers are required to be highly flat in order to increase the integration density and the productivity of the devices. Especially edge roll off, which occurs during polishing process as the final stage of the wafer manufacturing and seriously deteriorates polished edge surface flatness, is strongly demanded to be diminished. However mechanism of generation of edge surface profile has yet to be clarified exactly, which makes it difficult to meet the demand. In this study, based on the elastic contact theory, a profile-generating model was proposed considering the effect of existing edge roll off on change in edge surface profile, concretely deterioration of flatness, improvement of flatness and convergence of profile. Based on the model, polishing pad with smaller deformation during polishing process was expected to be effective in achieving highly flat edge surface profile without edge roll off. Estimation of pad deformation and polishing experiments on silicon wafers confirmed that polishing pad with smaller deformation during polishing process achieved higher edge surface flatness.