Reaction of implanted n isotope with SiO2 near Si3N4-Film and SiO2-substrate interface

We have investigated 100 keV N-15 (90% enriched) implantation effects on Si3N4 films on SiO2-glass-substrate. The Si3N4 films were prepared by using reactive RF-magnetron-sputter-deposition method in N-2 (natural isotope abundance) gas at room temperature. The composition and film thickness were measured by Rutherford backscattering spectroscopy (RBS) and optical absorption spectroscopy. The RBS and optical absorption spectroscopy show increase in the film thickness with the stoichiometric composition, by N-15 ion implantation. These results and depth distribution of the implanted N-15, which is obtained by nuclear reaction analysis (NRA), lead to formation of Si-3 N-15(4) film (embedded isotope rich nitride film). Enrichment of N-15 in the grown silicon-nitride film is estimated to be similar to 70%.