Abstract: A new model of the rapid initial oxidation in dry oxygen for silicon is presented. In this model, both the effects of the change in the interfacial reaction rate coefficient and the enhanced oxygen diffusion on the high, initial oxidation rate of silicon are considered. Using this new model, the trouble and the limitation existing in the so-called fixed positive charge model which was presented by Schafer and Lyon can be avoided. Compared with the oxidation model used in the process simulation program-SUPREM-Ⅲ, our model has a clearer physical meaning. The formula of the model takes the similar form to the linear-parabolic oxidation model, BO it is very suitable for VLSI process simulation. In addition, the model can also explain why there is no rapid initial oxidation of silicon in wet oxygen, and why the initial oxidation rate of nondoped polycrystalline silicon is even larger than that of the <111>-oriented single crystalline silicon.