Stability of Excess Oxygen Atoms near Oxide Precipitate and Oxygen Solubility in Silicon Crystal

Abstract

The interfacial structure of oxide precipitate and the surrounding Si crystal, OP/Si, has been investigated by focusing on the stability of excess O atoms near the interface in connection with the solubility of O in Si. Excess O atoms become more stable near the interface than those in the interstitial sites in the Si matrix far from the interface. The thickness of the transition layers was at most that of the three Si atomic layer in models through ab initio calculations. Transition layers with a thickness of several nm have been previously detected by electron energy loss spectroscopy (EELS) and modeled for analysis by using the Hakoniwa method. In a lower temperature range, the increase in the ratio of captured interstitial O atoms in a transition layer was expected by lowering the temperature, and the possible range of O solubility in Si in this range was derived. In a higher temperature range, the interface model without transition layers showed that the solubility turns out to be the well-known Arrhenius-type and reproduces the experimental results. And finally, we propose a semi-macroscopic model for the OP/Si interface to explain the previously reported EELS results.