Thermal nitridation kinetics of silicon wafers in nitrogen atmosphere during annealing

Silicon wafers were annealed in pure and low-purity nitrogen gas at temperatures from 800 to 1200 °C. The surfaces of the annealed samples were investigated by means of X-ray photoelectron spectroscopy and optical microscopy. It was found that silicon wafers could react with nitrogen molecules to form silicon nitride films at temperatures higher than 1100 °C in pure nitrogen atmosphere. The thickness of the silicon nitride films thermally grown in pure nitrogen gas at 1100 and 1200 °C for up to 4 h was measured. The maximum thickness was about 50 nm, and the growth kinetics of direct thermal nitridation at 1100 and 1200 °C was obtained.