Structure analysis of silicon dioxide films formed by oxidation of silane

Abstract

The structure of a silicon dioxide film deposited on a silicon substrate by oxidation of silane at 340°C was analyzed by using electron‐diffraction and infrared absorption techniques. The Si–O, O–O, and Si–Si distances were determined by the radial‐distribution analysis to be 1.62, 2.6, and 3.1 Å, respectively. The deposited film consists of SiO₄ tetrahedra, but its atomic arrangement is more irregular than that in a thermally grown silicon dioxide film. As the deposited film is heated in nitrogen at 1000°C, the density increases and approaches that of thermally grown silicon dioxide film. No change occurs in average atomic distance by heating, but the atomic arrangement approaches that in the thermally grown silicon dioxide film. This is also explained from the narrowing of the Si–O–Si bending vibrational band near 450 cm⁻¹ (22 μ) in the infrared‐absorption spectrum.