Evolution of the infra-red vibrational modes upon thermal oxidation of Si single crystals

Upon oxidation of Si single crystals with a (100) orientation in dry O-2 at temperatures between 773-1273 K, infrared absorption spectra have been measured in the wavenumber region of 400-4000 cm(-1) by Fourier-transform infrared spectroscopy. The Si-O-Si stretching, bending and rocking vibrational modes at 1075, 810 and 450 cm(-1) are identified. They slowly increase in integrated intensity up to 1023 K and then a significant rise follows upon thermal oxidation for a fixed period of time. These infrared vibrational modes reveal a parabolic time dependence with respect to their integrated intensity upon thermal oxidation at 1023 K for various times. The most remarkable issue is that the stretching vibrational mode at 1000-1300 cm(-1) could be decomposed into at least four components, and that the low-frequency component and the predominant one reveal their characteristic temperature dependence regarding frequency and linewidth. These results are compared with the infrared spectroscopic studies of Si oxide films that have been done previously, and their implications are discussed as well. (C) 1997 Elsevier Science Ltd.