Oxidation enhanced diffusion of boron in silicon at 650–750 °C using steam in the range 1–15 atmospheres

Buried boron layers were epitaxially grown on single crystal silicon substrates and subjected to steam oxidation at 650–750 °C and pressures of 1, 5, and 15 atm. The layers were approximately 200 nm thick and capped by 400 nm of undoped silicon. The boron concentration varied from 8×1017 to 4×1018 atoms/cm3. The ensuing enhanced boron diffusion was modeled on the assumption that the oxidation maintained a supersaturation of interstitials at the surface which was proportional to the square root of the oxidation rate. Fully coupled dopant-defect diffusion equations were necessary to accurately model the oxidation enhanced diffusion.