Precipitation of boron in silicon on high-dose implantation

Abstract

Precipitation of boron implanted in silicon with a dose of 1 × 1016 cm−2 is studied in relation to the concentration of substitutional boron \( C_{B_0 } \) introduced before implantation and before subsequent annealing at 900°C. It is shown that \( C_{B_0 } \) = 2.5 × 1020 cm−3 is the critical concentration, at which the formation of precipitates is independent of the concentration of point defects introduced by implantation (far from or close to the mean projected range Rp) and constitutes the prevailing channel of deactivation of boron. At lower concentrations \( C_{B_0 } \) close to the equilibrium concentration, precipitation is observed only far from Rp, in the regions of reduced concentrations of point defects. At the same time, in the region of Rp with a high concentration of point defects, most boron atoms are drawn into clustering with intrinsic interstitial atoms with the formation of dislocation loops and, thus, become electrically inactive as well.