Influence of the native oxide layer on the silicon surface during initial stages of nitridation

Thin SiO2 layers were produced by thermal oxidation of Si wafer material. T o study the effect of nitridation on the oxide layers, the specimens were n itrided in a furnace at high temperature. Non-destructive ion beam analysis was performed to determine changes in the elemental concentrations and dep th profiles of the major components. In particular, N and O concentrations were measured using the non-resonant nuclear reactions N-14(d,alpha)C-12 an d O-16(d,p)O-17, respectively. To obtain depth profiles of the as-prepared and nitrided specimens, the samples were measured with RBS and heavy ion el astic recoil detection analysis. The ion beam analyses revealed an increase in thickness of the SiO2 layers with temperature. The specimens nitrided a t 1200 degreesC were almost free of N. Surface topology investigations with scanning electron microscopy revealed concentric annular artificial patter ns at the surfaces. In the centre of the pattern, only silicon was measured . Additionally, a band consisting of Si, O, and N surrounding the pattern w as discovered. The findings are in agreement with specimens prepared at hig her temperatures.