The Effect of Chemical Cleaning on the Kinetics of Thermal Oxidation

Abstract

A detailed study concerning the effect of chemical cleaning on the kinetics of silicon thermal oxidation is presented. This investigation included a wide range of temperature, thickness, and chemicals for both (100) and (111) silicon wafers. The results indicate that treatment by ammonium peroxide causes substantial retardation of dry oxide growth as compared with acidic solutions such as HC1, H2SO4, HNO3, and HF. The effect of chemical cleaning varies with thickness, temperature, doping, ambient, and crystal orientation. Analysis based on the Deal-Grove model shows that the principal effect of chemical cleaning is on the linear-rate constant and the initial rapid oxidation. A series of two-step oxidation experiments was also conducted with different thermal and chemical treatments between steps. The results demonstrate that the oxidation is affected by the surface film produced on the silicon by chemical cleaning and that this thin film remains on the outer surface of the growing oxide throughout the oxidation process.