Boron implantation into silicon amorphized by tin implantation

Abstract

Implanting 1.0 × 1015 118Sn+ cm−2 at 120 keV into n-type <100> or <111> Si forms a 0.092 μm thick layer of amorphous Si. Subsequent implantation of 1.0 × 1015 11B+ cm−2 at 10 keV, followed by annealing for 30 min at 800° C results in 0.23 μm and 0.18 μm deep junctions in <100> and <111> Si respectively. Annealing for 30 min at 900° C results in junctions that are 0.29 μm deep in <100> Si, and only 0.23 gm deep in <111> Si. After having been annealed at both temperatures a discontinuous band of dislocation loops remains at the original amorphous-crystalline interface in <100> Si, whereas microtwins and stacking faults are observed in regrown <111> Si. These latter defects probably retard the electrical activation and concomitant substitutional diffusion of boron in <1·11> Si causing the junctions to be shallower and to have lower carrier concentrations. The defects, however, do not seem to contribute to the leakage current of the junctions.