A novel appproach to secondary defect reduction in separation by implantation of oxygen material

Abstract

The effect of a preanneal Si implant after the initial O implant in the fabrication of separation by implantation of oxygen (SIMOX) material has been examined. In addition to studying the effect of the Si dose and implant temperature on the residual disorder, the Si implant energy was varied in order to elucidate the mechanism of secondary defect reduction in SIMOX material. Initial experiments showed that a low implant temperature (150 °C) and a moderate dose (5×1016 cm−2) of 4.2 MeV Si ions were the most successful in reducing the volume fraction of polycrystalline Si at the front Si/SiO2 interface. A systematic study of low-, medium-, and high-energy Si implantation with ion ranges less than, equal to, and greater than the initial O implant has been performed. The Si range and defect production per ion were shown to be most important in determining the final defect structure in SIMOX material formed by MeV O implantation in Si. Low- and medium-energy Si-implanted SIMOX material has a more homogeneous buried SiO2 layer and a less defected Si overlayer than virgin SIMOX (O-implanted Si which has not received a preanneal Si implant). The high-energy Si implant slightly reduced the defect density in the Si overlayer and planarized the back Si/SiO2 interface for SIMOX material formed at an implantation temperature of 300 °C but did not homogenize the buried SiO2 layer.