Redistribution of boron in silicon after high−temperature proton irradiation

Abstract

We have measured the distribution of boron in silicon, using secondary ion mass spectroscopy or nuclear reactions, after irradiation at 850°C by protons of energy 250−450 keV. The fluence was 1×10¹⁷ to 6×10¹⁷ protons/cm². Prediffused and uniformly doped samples have been studied. It is found that the boron distribution is considerably modified: the boron concentration shows a peak near the end of the proton range, where the defect creation rate is highest. This anomaly cannot be explained by using solely simple diffusion theory, and depends on boron−defect interactions, such as the formation of precipitates or complexes. As a consequence, the interpretations of radiation−enhanced diffusion experiments must be discussed again.