Machining Mechanisms of Si Wafers in Mechanochemical Polishing by Soft Abrasives
The mechanism of the mechanochemical polishing of Si wafers with BaCO3, CaCO3 and ZnO abrasives was investigated by polishing experiments carried out in air, O2 and Ar gas environments on dry condition and static heat treatment experiments of mixed powder of BaCO3 and Si with various mixture ratios for analyzing the reaction mechanism at the interface in polishing operation. Results obtained were (1) Si wafers were smoothly and effectively polished with these all mechanochemical abrasive whether O2 gas existed in the surrounding environment or not, (2) Heat treatment of the mixed powder suggested that oxidation of Si was more actively promoted even when existence of BaCO3 powder was only a little in the mixture and that formation of Ba-Si oxide increased as the mixture ratio of BaCO3 powder to Si powder increased, (3) As the mechanochemical polishing mechanism, two-step reaction process would be the most reasonable, that is, chemical attack of the mechanochemical abrasive for oxidizing the Si surface as the first step and further chemical reaction to form reaction products between the formed SiO2 and the abrasive as the second step.
Yury M. Baron, Jun'ichi Tamaki and Tsunemoto Kuriyagawa
N. Yasunaga "Machining Mechanisms of Si Wafers in Mechanochemical Polishing by Soft Abrasives", Key Engineering Materials, Vols. 291-292, pp. 385-388, 2005