Microscopic mechanism responsible for radiation-enhanced diffusion of impurity atoms

Modeling of radiation-enhanced diffusion of boron and phosphorus atoms during irradiation of silicon substrates respectively with high- and low-energy protons was carried out. The results obtained confirm the previously arrived conclusion that impurity diffusion occurs by means of the "impurity atom - intrinsic point defect" pairs and that the condition of the local thermodynamic equilibrium between substitutional impurity atoms, nonequilibrium point defects created by irradiation, and the pairs is valid. It is shown that using radiation-enhanced diffusion, one can form a special impurity distribution in the semiconductor substrate including retrograde profiles with increasing impurity concentration into the bulk of a semiconductor. The calculations performed give clear evidence in favor of further investigation of various doping processes based on radiation-enhanced diffusion, especially the processes of plasma doping, to develop a cheap method for formation of specific impurity distributions in the near surface region.