Oxidation of silicon surface with atomic oxygen radical anions

The surface oxidation of silicon (Si) wafers by atomic oxygen radicalanions (O^- anions) and the preparation ofmetal--oxide--semiconductor (MOS) capacitors on the O^--oxidized Si substrates have been examined for the first time. TheO^- anions are generated from a recently developed O^-storage-emission material of [Ca₂₄Al₂₈O₆₄]⁴⁺.4O^- (C12A7-O^- for short). After it has beenirradiated by an O^- anion beam (0.5mu A/cm²) at300⁰C for 1--10 hours, the Si wafer achieves an oxide layerwith a thickness ranging from 8 to 32nm. X-ray photoelectronspectroscopy (XPS) results reveal that the oxide layer is of amixture of SiO₂, Si₂O₃, and Si₂O distributed in different oxidation depths. The features of the MOS capacitor ofx/Si> are investigated by measuringcapacitance-voltage (C-V) and current-voltage (I-V) curves. Theoxide charge density is about 6.0 times 10¹¹cm²derived from the C-V curves. The leakage current density is in theorder of 10^-6A/cm² below 4MV/cm, obtained from the$I-V$ curves. The O^- anions formed by present method wouldhave potential applications to the oxidation and thesurface-modification of materials together with the preparation ofsemiconductor devices.