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 R _p ) 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 R _p , in the regions of reduced concentrations of point defects. At the same time, in the region of R _p 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.