Effect of Carbon on Diffusion of Boron in SiGe between 940 – 1050 °C

Abstract

ABSTRACTThe effect of carbon on boron diffusion was studied in Si and strained SiGe. Several types B containing matrices were grown: (i) Si, (ii) Si containing 0.1% C peak, (iii) SiGe with 11% Ge and (iv) SiGe with 11% Ge and with a 0.1% C peak, using gas-source molecular beam epitaxy (MBE). The combination of Si, Si with C, SiGe and SiGe with C matrices allowed us to separate the effects of Ge and C on B diffusivity. To ensure non-injection surface conditions, low temperature silicon dioxide (LTO) and silicon nitride layers were deposited on top of samples in that order. These samples were then rapid thermal annealed (RTA) at 940, 1000 and 1050°C in an O2 ambient.Diffusion coefficients of B in each type of matrix were extracted by computer simulation, using SIMS profiles obtained from samples before and after the RTA treatment. Diffusion coefficient is reduced by both Ge and C, the suppression by C being more profound. The results are compared to and found to be in reasonable agreement with limited data available in literature.