Semiconductor silicon plays a significant role in the microelectronics industry. In this paper, the effects of polishing pressure on electrochemical characteristics of silicon wafers during chemical mechanical polishing (CMP) were investigated by dc polarization and ac impedance techniques. The results revealed that polishing pressure had a strong influence on the electrochemical behavior of silicon wafers. Mechanical abrasion improved the removal of the passivating layer and enhanced the wafer oxidation rate. The corrosion current density and the polishing rate increased sublinearly with applied pressure. Also, the CMP process of silicon wafers can be considered a sequential formation causing film removal, which was confirmed by testing the change with electrochemical impedance spectroscopy. (c) 2008 The Electrochemical Society.