Electrochemical Study for the Characterization of Wet Silicon Oxide Surfaces

摘要

Because wet ultra thin silicon oxides are extensively used in the microelectronic industry, we have investigated the growth of these oxides in various aqueous solutions using three main electrochemical techniques, ⅰ) open circuit potential variation with time, ⅱ) linear voltammetry in a narrow range of potential, ⅲ) electrochemical impedance spectroscopy under various bias potentials, to collect quantitative data regarding the growth kinetics of silicon oxide passivating layer, mainly at room temperature. In oxidizing alkaline solutions, the surface silicon oxide layer reached a limiting thickness value with time, related to a oxidation/dissolution stationary behaviour. An interesting observation in this study was that the oxide layer was permeable to ions and oxidizing agents in alkaline media. Our techniques lead to the determination of the etching rate of Si substrate under the protecting Si oxide layer.