SI OXIDATION PROCESS

摘要

PURPOSE:To provide a new Si wafer oxidation method which lowers an interface level density and minimizes variation in a film thickness by exposing Si in a specific gas atmosphere. CONSTITUTION:If an Si wafer is exposed directly after having cleaned the Si wafer by HF in an NO2 gas atmosphere, it is possible to form an SiO2 whose interface level density fails to exceed 109/cm2 at a thickness of 20 to 30A even in a normal temperature on the surface of the Si wafer. Compared with the interface level density of a natural oxide film, which is 1012/cm2, and formed by the exposure of the film in an atmosphere or more particularly, an O2 gas ambient atmosphere which contains H2O slightly, the interface level of the wafer is extremely small. At the same time, the growth speed of the oxide film is faster two or three times while the life time is extremely longer with NO2 gas. Therefore, there exists virtually no variation in the film thickness. Moreover, it is acceptable to use No gas, N2O gas or SO3 or H2O2 gas in stead of NO2. At the same time, the heating temperature of the Si wafer is applicable in a wider range, say, from the ambient temperature to 1200 deg.C.