Structural studies of silicon oxynitride layers formed by low energy ion implantation

Abstract

Silicon oxynitride (SixOyNz) layers were synthesized by implanting 16O2+ and 14N2+ 30keV ions in 1:1 ratio with fluences ranging from 5×1016 to 1×1018ionscm−2 into single crystal silicon at room temperature. Rapid thermal annealing (RTA) of the samples was carried out at different temperatures in nitrogen ambient for 5min. The FTIR studies show that the structures of ion-beam synthesized oxynitride layers are strongly dependent on total ion-fluence and annealing temperature. It is found that the structures formed at lower ion fluences (∼1×1017ionscm−2) are homogenous oxygen-rich silicon oxynitride. However, at higher fluence levels (∼1×1018ionscm−2) formation of homogenous nitrogen rich silicon oxynitride is observed due to ion-beam induced surface sputtering effects. The Micro-Raman studies on 1173K annealed samples show formation of partially amorphous oxygen and nitrogen rich silicon oxynitride structures with crystalline silicon beneath it for lower and higher ion fluences, respectively. The Ellipsometry studies on 1173K annealed samples show an increase in the thickness of silicon oxynitride layer with increasing ion fluence. The refractive index of the ion-beam synthesized layers is found to be in the range 1.54–1.96.