Outdiffusion and diffusion mechanism of oxygen in silicon

Abstract

The outdiffusion profiles of oxygen in Czochralski Si(111) within the temperature range 700–1160 °C and for three processing conditions (nitrogen atmosphere, steam oxidation, and phosphorus indiffusion) were measured by secondary ion mass spectrometry. The diffusivity and solubility of oxygen in Si were determined by fitting these profiles to a simple diffusion model. Oxygen diffusivity shows little or no dependence on processing conditions and can be expressed as D=0.14 exp(−2.53 eV/kT) cm2 s−1 for the temperature range studied. Our observations show that point defects in Si have little effect on oxygen diffusion and demonstrate that oxygen diffuses primarily via an interstitial mechanism. Oxygen solubility was the largest during steam oxidation.