Oxidation of silicon surface with atomic oxygen radical anions

Abstract

The surface oxidation of silicon (Si) wafers by atomic oxygen radical anions (O− anions) and the preparation of metal-oxide-semiconductor (MOS) capacitors on the O− -oxidized Si substrates have been examined for the first time. The O− anions are generated from a recently developed O− storage-emission material of [Ca24Al28O64]4+.4O−(C12A7-O− for short). After it has been irradiated by an O− anion beam (0.5 μA/cm2) at 300°C for 1–10 hours, the Si wafer achieves an oxide layer with a thickness ranging from 8 to 32 nm. X-ray photoelectron spectroscopy (XPS) results reveal that the oxide layer is of a mixture of SiO2, Si2O3, and Si2O distributed in different oxidation depths. The features of the MOS capacitor of < Al electrode/SiOx/SI > are investigated by measuring capacitance-voltage (C — V) and current-voltage (I — V) curves. The oxide charge density is about 6.0 × 1011 cm−2 derived from the C — V curves. The leakage current density is in the order of 10−6A/cm2 below 4MV/cm, obtained from the I — V curves. The O− anions formed by present method would have potential applications to the oxidation and the surface-modification of materials together with the preparation of semiconductor devices.