Boltzmann–Matano analysis based model for boron diffusion from polysilicon into single crystal silicon

Abstract

The diffusion of boron in single crystal silicon has been modeled following a BF2 or boron implant in a polysilicon layer deposited on a single crystal silicon substrate. The effective concentration-dependent diffusivities of boron in single crystal have been extracted using Boltzmann–Matano analysis from the experimental boron diffusion profiles measured using secondary ion mass spectrometry. The effective boron diffusivities are found to be independent of the implant dose. A new analytical model for concentration-dependent boron diffusivities has been implemented in the PEPPER simulation program to accurately model the boron diffusion profiles in single crystal silicon for a polysilicon-on-single-crystal-silicon structure. The model has been verified for a wide range of furnace anneal conditions (800–950 °C, from 30 min to 6 h), and implant conditions (BF2 doses varied from 5×1015 to 2×1016 cm−2 at 70 keV and boron dose of 5×1015 cm−2 at 20 keV).