Local Atomic Structure of Thermally Grown SiO₂ Films

Abstract

We have grown thin films of SiO₂ by thermal oxidation of crystalline silicon and have determined as functions of the growth and annealing conditions: (1) the frequency, v, and line-width, ∆v,of the Si-O infrared (ir) active bond-stretching absorption band; (2) the index of refraction, n, at 632.8 nm; and (3) the intrinsic in-plane film stress, σ_x(SiO₂). Linear relationships between; (1) ∆v and v, and (2) n and v, are explained in terms of a microscopic model in which the determinant atomic scale variable is the bond-angle, 2θ, at the oxygen atom site. Using this model, we have been able to obtain an approximate value of the in-plane Young’s modulus for SiO₂ from a combinatidn of stress and ir measurements.