Basic research on polishing with ice bonded nanoabrasive pad

New approach to polish silicon wafers was proposed in this study, where nanoabrasives were bonded by ice to make ice bonded fixed abrasive pads (IFA) and the wafer was polished with the IFA under cryogenic conditions. After the introduction of the preparation process of the IFA with nanosized CeO2 and Al2O3 abrasives, polishing experiments of silicon wafers were carried out, and polishing mechanism was discussed. The results show that a supersmooth surface with roughness of Ra 0.568 nm is obtained when polished with Al2O3 IFA and Ra 0.369 nm when polished with CeO2 IFA. No microcracks are found in the subsurface of the workpiece. Since the grain size is about 80-100 nm in diameter and there exists a soft corrosion layer and a stable thin liquid film between the silicon wafer and the IFA during polishing, the real cutting depth of the abrasive decreases and the material is removed in a ductile mode. The chemical corrosion and mechanical removal simultaneously exist during the cryogenic polishing of silicon wafer; therefore the material removal is dominated by the coactions of ductile regime machining and chemical corrosion. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3125272]