The Growth of Oxidation Stacking Faults and the Point Defect Generation at Si ‐ SiO Interface during Thermal Oxidation of Silicon

Abstract

A general relation for the growth and retrogrowth of oxidation-induced stacking faults (OSF) has been developed with three key observations from OSF experiments: (i) the growth rate of OSF is independent of their size and density, (ii) the ambient, pressure, and time dependences are explained by an oxidation rate dependence of the supersaturation of silicon self-inter-stitials in silicon which induces the fault growth, and (iii) the shrinkage of the faults in inert or oxidizing ambients is controlled by the same mechanism with activation energy of ~4.8 eV. To explain the oxidation rate dependence of interstitial supersaturation, a two-step oxidation model is proposed. In the first step, the lattice silicon atoms near the Si-SiO2 interface oxidize to form SiO2, but leave a substantial number of silicon atoms as interstitials near the interface. In the second step, these excess silicon atoms flow interstitially mostly into the oxide where they react with oxygen atoms until the oxidation is essentially complete, while a small fraction flows into the bulk silicon. The balance of the reactions in the two steps determines the silicon interstitial supersaturation in silicon which controls the growth rate of OSF. The correlation between the OSF and other oxidation-induced phenomena, e.g., oxidation-enhanced diffusion (OED), and oxide fixed charge, Qf, formation is also discussed based on the model. The correlation supports the postulate that these phenomena are caused by oxidation via the same point defect mechanism. © 1981, The Electrochemical Society, Inc. All rights reserved.