Reduction of Secondary Defects in High Energy O-Implanted Si by High Energy Si Irradiation

Abstract

ABSTRACTThe effect of 4.2 MeV, low dose Si irradiation before annealing of 1 MeV, high dose O-implanted Si has been studied. Si irradiation results in differences in the defect structure both before and after high temperature annealing. With no Si irradiation, annealing results in polycrystalline Si (polySi) formation and microtwinning at the front SiO2/Si interface. With Si irradiation, the polySi volume fraction is greatly reduced after annealing, twinned Si having grown in its place. Si irradiation has no effect on Si inclusions within the SiO2 layer. The dependence of secondary defect formation on Si dose and implant temperature is presented. In particular, Si irradiation at low implant temperatures (150°C) and moderate doses (5×1016 cm−2) is shown to be most effective in the reduction of the polySi volume fraction at the front SiO2/Si interface.