The reaction kinetics of iron-boron formation and dissociation in p-type silicon were investigated. The results indicate that the reaction kinetics depend strongly on the relative position of the ionization energy of interstitial iron and the Fermi level. At temperatures below a transition temperature where the ionization energy of interstitial iron is equal to the Fermi level, the iron-boron pairing reaction is dominated by the electrostatieally enhanced recombination process between interstitial iron and substitutional boron. This pairing reaction is limited to the iron diffusion which may be described by the diffusion coefficient correlated by WeberJ At temperatures above the transition temperature, the concentrations of ionized and neutrally charged interstitial iron species are in equilibrium. The equilibrium reaction, which is facilitated by thermally excited electrons, gives rise to a deionization of the charged interstitial iron species and in turn causes the dissociation of the iron-boron pairs. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.93.24.73 Downloaded on 2015-03-17 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.93.24.73 Downloaded on 2015-03-17 to IP

The formation kinetics of oxygen thermal donors in silicon was investigated. The result indicates that the diffusivity of interstitial oxygen can be used to explain the aggregation process of oxygen atoms at the thermal donor annealing temperatures. For the annealing time <105 s, the thermal donor concentration increases linearly with increasing time, while the number of oxygen atoms per donor remains unchanged. This result implies that an equilibrium concentration of oxygen atoms in the electrically active clusters could exist at the donor anneal temperature.

A relatively simple experimental method to estimate a diffusivity of silicon interstitials is described. In the low-temperature range between 460 and 500 °C, oxygen thermal donors are used as a monitor for silicon interstitials. The estimated diffusivity of silicon interstitials at oxygen-donor-formation temperatures is fitted to previously-published results from oxidation-enhanced and retarded-diffusion experiments at temperatures above 950 °C. In the temperature range between 460 and 1200 °C, the diffusivity of silicon interstitials is described by the Arrhenius equation, Di=3.35×10−1 exp(−1.86/kT) cm2/s.

A real-time simulation of the point-defect reactions near the solid and melt interface of a 200 mm diam Czochralski silicon crystal was performed. The results from the thermal stress calculation accounting for the temperature dependence of the elastic modulus of silicon indicate that the thermal stresses in the vicinity near the solid and melt interface are far above the silicon yield strength. Therefore, it is suggested that the effect of thermal stresses on the point defect reactions in a growing crystal is negligible. In this work, the crystal cooling conditions are found to have a significant impact on the point defect reactions. Under fast cooling conditions, the simulator predicts a supersaturation of vacancies in the vicinity near the solid and melt interface while the silicon interstitial concentration retained in the crystal grown under slow cooling conditions could increase significantly. The present results also indicate that the point defect reactions near the solid-melt interface as well as at the crystal periphery are governed predominantly by a short-range pair recombination which is driven by the chemical potential of point defect saturation. The contribution of a long-range or up-hill diffusion, on the other hand, is considered to be negligible.

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