INTRINSIC STRAIN IN SIO2 THIN-FILMS

The oxidation of silicon to form SiO2 is accompanied by large changes in volume. Existing models of silicon oxidation indicate that almost a ll of this volume change takes place normal to the oxidation front. Ho wever, available experimental results clearly indicate that there exis ts a small component of expansion in the plane of oxidation, leading t o what may be termed as intrinsic, in-plane strain in SiO2 films on si licon substrates. We reanalyze the experimental data of Kobeda and Ire ne (J. Vac. Sci. Technol. B 6, 720, 1986) to estimate this quantity, a rriving at a value of approximately 2 X 10(-3). The effect of this int rinsic strain upon the oxide film stresses is then examined for planar and nonplanar oxidation. Implications of these results for standard o xidation prediction schemes are discussed. (C) 1998 American Institute of Physics. [S0021-8979(98)02002-7].