Enhanced oxygen diffusion in silicon at thermal donor formation temperature

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Abstract
From the outdiffusion profiles of oxygen in Czochralski silicon at 500 °C measured with secondary ion mass spectrometry (SIMS), oxygen diffusivities of 2.5–4.0×10−14 cm2 s−1 are deduced, which are enhanced nearly four orders of magnitude relative to the normal diffusivity. Diffusion of implanted oxygen-18 in float-zone silicon at 400–525 °C yields SIMS profiles consisting of an exponential decay of oxygen concentration. The exponential profiles of oxygen-18 above background (1014 cm−3) as deep as 4–16 μm also show direct evidence of enhanced long-range oxygen diffusion. The results of enhanced oxygen diffusion can be explained with a fast-diffusing species, which is in dynamical equilibrium with the interstitial oxygen.