Analysis of N isotope depth profiles in search for reaction of implanted nitrogen with substrate near Si3N4–nitride-film and SiO2-glass-substrate interface

We have measured depth profiles of N isotopes by Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) before and after implantation of 100 keV N isotopes into Si3N4 films on SiO2-glass substrates, which were prepared by using RF-magnetron-reactive-sputtering deposition method in N2 gas. The film thickness is ∼200 nm and comparable with the calculated projected range, 180 nm (TRIM1997) of 100 keV N ions. We find that the nitride film thickness has increased after N implantation with nearly stoichiometric composition. Optical absorption spectra also show the increase of the film thickness. According to NRA, the implanted 15N are found to be located around the Si3N4 film–substrate interface. It also appears that the increase of the film thickness multiplied by the film density approximately equals to the implantation dose. These results imply reaction of implanted nitrogen with the substrate and growth of Si3N4.