Nitridation of Silicon and Oxidized-Silicon

The nitridation of silicon and oxidized-silicon has been studied. The nitrided films were prepared at 900~176 under ammonia partial pressures of 10-3 to 5 kg/cm 2in nitrogen and were analyzed byellipsometry and Auger electron spectros-copy. For films formed by nitridation of silicon, we found that the growth kinetics and properties such as chemical compo-sition, etching rate, and oxidation resistance were independent of the ammonia p rtial pressure. The nitridation of silicon can be explained by a modified Ritchie-Hunt theory, which assumes that very slow surface reaction at the ammonia-nitride interface is the rate-determining factor, using the logarithmic rate law. According to this modified Ritchie-Hunt theory, the nitridation f silicon proceeds mainly by cation migration under a constant electric field. On the other hand, it was found that the nitridation of oxidized-silicon depended strongly on the ammonia parital pressure. This dependence may be caused by diffusion of ammonia or its derivatives through the oxide. The conversion of silicon dioxide to silicon oxynitride occurred throughout the oxide. Presently, silicon dioxide film is most commonly used as a gate insulator. Soon, however, thin amorphous di-electric films less than 200A thick will be required for silicon integrated circuit technology for use as gate in