The Effect of Growth Ambients on the Local Atomic Structure of Thermally Grown Silicon Dioxide Thin Films

Abstract

This paper represents a study of the local atomic structure of SiO₂ films formed by thermal oxidation in dry oxygen, pyrolytic steam, and a variety of different sequences of these arabients. All oxidations were carried out at 850°C. Local atomic structure was studied via infrared spectroscopy (IR). The growth ambient dependence of the frequency v, and half-width Δv, of the bond stretching feature, and the refractive index, n, was investigated. Consistent with previous work [1,2] it was found that when the majority of the sample thickness was grown in steam the oxides were generally less dense than dry oxides. Also, the last ambient in a sequential oxidation process was found to have the most influence on the oxide properties. The observed variations in v, Δv, and n could be readily explained in terms of systematic changes in the bond angle at the oxygen bonding site between corner connected tetrahedra.