The effect of the annealing ramp rate on the formation of voids in silicon

We show the strong dependence on annealing ramp rate of residual open-volume defects in silicon following helium ion implantation and annealing. Helium was implanted at 60 keV energy, 1 × 1016 cm−2 fluence into silicon and subsequently annealed to 800 °C for 30 min, with ramp rates ranging from 1 to 100 °C s−1. The residual defect distribution was probed by means of positron annihilation spectroscopy and ion channeling, with results demonstrating a strong dependence on the ramp rate. For these conditions, open-volume defects to which the positron technique is sensitive are present in significant concentrations only for annealing ramp rates greater than 5 °C s−1.