Effect of annealing temperature ramp rate on bubble formation in helium-implanted silicon

Abstract

We have implanted He3 into Si(100) at 1.0MeV ion energy and to fluences ranging between 2×1015 and 2×1016cm−2, followed by annealing at 700°C. Heating ramp rates have been systematically varied over more than two decades (0.3°C∕sto100°C∕s) at each fluence. The retention of He3 is measured through the He3(d,p)He4 nuclear reaction yield. We show that gas retention can be varied by more than an order of magnitude even while the other anneal parameters—anneal temperature and anneal time—are maintained constant. Cross-sectional scanning electron micrographs confirm the presence of planetarylike cavity structures at a depth closely matching that calculated for the damage peak.