Effects of nitrogen and argon plasma-immersion ion implantation on silicon and its oxidation

Nitrogen and argon ions were implanted in silicon at energy of 10 and 20 keV by the plasma immersion ion implantation (PIII) technique. The implantation dose was varied from 1013 to 1017 ions/cm2. Ellipsometric measurements were carried out on the samples implanted at various doses. Silicon wafers implanted with high doses of nitrogen (1017 ions/cm2) showed the formation of a SiNx layer. Samples implanted with a high dose of argon (1016 ions/cm2) also resulted in an optically transparent, damaged layer of refractive index in the range 2.01–2.32. All the samples were then subjected to various oxidation atmospheres. Retardation of the oxidation rate for nitrogen-implanted samples and enhancement for argon-implanted samples was noted with increasing implantation dose. Metal-oxide semiconductor (MOS) capacitor structures were then fabricated using the oxidised samples. Capacitance–voltage (C–V) characterisation was carried out to study the electrical properties of the oxidised films. This paper reports the results of electrical and optical measurements carried out on these samples.