Boron in Near‐Intrinsic and Silicon under Inert and Oxidizing Ambients—Diffusion and Segregation

Abstract

The diffusivity of boron in and silicon is experimentally determined under both inert and oxidizing (dry ) ambient conditions in the range of temperatures 850°–1200°C. The boron is implanted at moderate dose and energy (70 keV) and subsequently activated by a moderate temperature anneal. The resulting profile ensures near‐intrinsic silicon at the processing temperatures and serves as initial condition for subsequent processing. Diffusivities and segregation coefficients are calculated as fitting parameters in numerical solution of the experiments. A systematic fitting procedure is used and the target experimental parameters are sheet resistances and junction depths. Inert ambient diffusivities agree well with previous measurements, thus demonstrating the integrity of newly published mobility data used in the simulations. Diffusivities in oxidizing ambient are enhanced, more so in than in silicon. The enhancement increases with decreasing temperature, being about 10 for at 850°C. It is demonstrated that there is good agreement between the observed diffusivity enhancement and growth of oxidation stacking faults if an interstitialcy mechanism is invoked to explain both phenomena. Observed segregation coefficients are different for the two silicon orientations but they obey the same activation energy over the temperature range.