Katsuhiko Miki

Diffusivity of oxygen in Czochralski silicon at 400–750 °C

Diffusivity of oxygen in Czochralski silicon crystal in the temperature range of 400–750 °C has been determined from macroscopic oxygen precipitation behavior. The oxygen diffusivities at several nucleation temperatures from 400 to 750 °C were deduced from precipitated oxygen concentrations after a series of precipitate growth heat treatments, 800 °C/4 h and 1000 °C/16 h, using an extended nucleation theory. The measured oxygen diffusivity at 450–650 °C is 2–4×10−14 cm2/s, independent of the temperature, and considerably larger than the generally accepted normal diffusivity of Di=0.13 exp(−2.53 eV/kT). Moreover, the diffusivity at 450 °C is found to be roughly proportional to the interstitial oxygen concentration. It is suggested that this dependence of oxygen diffusivity on interstitial oxygen concentration can be explained by a model involving fast diffusing oxygen molecules.