Characterization of light element impurities in ultrathin silicon-on-insulator layers by luminescence activation using electron irradiation

Nakagawa, Satoko*; Tajima, Michio*; Hirose, Kazuyuki*; Oshima, Takeshi; Ito, Hisayoshi

Light element impurities in ultrathin top Silicon layers of silicon-on-insulator (SOI) wafers were investigated by a luminescence activation method using electron irradiation. Photoluminescence (PL) measurement using ultraviolet (UV) light excitation was carried out of various commercial SOI wafers irradiated with electrons. The C-line related to a complex of interstitial carbon and oxygen impurities and the G-line related to a complex of interstitial and substitutional carbon impurities in the top Si layer with a thickness down to 62 nm were observed after electron irradiation. There were differences in the impurity concentration depending on the wafer fabrication methods and also that there were variations in these concentrations in the respective wafers. The present method is a verypromising tool to evaluate the light element impurities in top Si layers.