Estimation of the intrinsic stress of thermally-oxidized film on an Si (100) surface and the emission ratio of Si atoms

The intrinsic stress of a thermally-oxidized film on an Si (100) surface is estimated using ab initio calculations based on quartz-cristobalite alloy-like models to investigate the effect of the emission of Si atoms. Two methods are examined; (i) thermal-equilibrium stress, and (ii) stress derived by Vegard’s low from the “composition” inferred from emission ratio of Si atoms at the interface, fitted to reported oxide film growth rates [M. Uematsu, et. al. Jpn. J. Appl. Phys., Part 2, 39, L699 (2000).]. Temperature-dependent stress rates (~0.2 GPa/400 ℃) are consistent for both the estimated values in (ii) and the reported experiments only below 800℃; however, the absolute estimated stress values differ from the reported value. This suggests that the film stress is mainly determined not by Si atoms emission but by the viscous flow. The viscous flow covers the entire SiO2 film, except the vicinity of the interface above 900℃.