Co-Precipitation of Carbon and Oxygen in Silicon: The Dominant Flux Criterion

Abstract

Due to the need of relieving the strain associated with the formation of SiO2 precipitates in silicon, co-precipitation of carbon with oxygen in silicon wafers may involve a large number of atomic and point defect species: oxygen, carbon, vacancies, and silicon self-interstitials. This allows many parallel mechanisms for strain relief to occur. In the present paper we first reason that this complex system may be reduced to that involving only three species: oxygen, carbon, and self-interstitials; and the strain relief mechanisms may be limited to two: that via self-interstitials and that involving carbon. We then propose a dominant (strain relief species) flux criteria to explain the behavior of carbon and oxygen co-precipitation in silicon. When the carbon flux is dominant, carbon should co-precipitate with oxygen. When the silicon self-interstitial flux is dominant, carbon should not co-precipitate with oxygen, even at high concentrations. Available data, spanning the temperature range of 450-1000?C and a carbon concentration range of from less than 0.5?1016 to 1?1018 cm-3, can be explained using this criterion.