Precipitation of As in thermally oxidized ion-implanted Si crystals

The As precipitation occurring during thermal oxidation of As implanted Si crystals has been studied by extended x-ray absorption fine structure measurements. (100) Si wafers, implanted with 3?ó1015/cm2 and 3?ó1016/cm2 As+ ions at an energy of 70 keV, were oxidized either in H2O ambient (wet) at 920¬?C or O2 (dry) at 1100¬?C. Precipitation of monoclinic SiAs occurs at the SiO2/Si interface for low temperature oxidation processes. In the case of 3?ó1016As/cm2, about 90% of the As forms SiAs precipitates, while for the lower dose a mixing of precipitates and As in substitutional-like sites is observed. On the other hand, when the high temperature oxidation is performed, most of the As (up to 90% for the 3?ó1015As/cm2 sample) is found in a substitutional-like configuration. ¬© 1998 American Institute of Physics.