Native Oxide Films and Chemical Oxide Films

Abstract

In Si oxidation, in addition to the high-temperature oxidation which creates gate oxide film, there is another oxide formation process: room temperature oxidation [1–5]. Controlling the growth rate of native oxide which forms on a cleaned wafer surface is, in the practical sense, of great importance in the semiconductor process. The existence of native oxide is a hindrance to the low-temperature growth of high-quality epitaxial Si thin film and the precise control of the thickness and quality of ultrathin gate oxide film. Native oxide is the cause of increases in the contact resistance of very small area contact holes. Native oxide can also be a source of metallic impurity contaminants, and, when native oxide growth is irregular, the micro-roughness of the Si surface increases after native oxide removal. Therefore, in order to achieve high-performance, high-reliability ULSI, it is imperative to elucidate the growth process of native oxide and establish methods to curb its growth rate.