AES analysis of nitridation of Si(lO0) by 2-10 keV Nl ion beams

Ion beam nitridation of Si(100) as a function of Nl ion energy in the range of 2-10 keV has been investigated by in-situ Auger electron spectroscopy @ES) analysis and Arf depth profiling. The AES measurements show that the nitride films formed by 4-10 keV N, + ion bombardment are relatively uniform and have a composition of near stoichiometric silicon nitride (Si,N,), but that formed by 2 keV Nz ion bombardment is N-rich on the film surface. Formation of the surface N-rich film by 2 keV Nl ion bombardment can be attributed to radiation-enhanced diffusion of interstitial N atoms and a lower self-sputtering yield. AES depth profile measurements indicate that the thicknesses of nitride films appear to increase with ion energy in the range from 2 to 10 keV and the rate of increase of film thickness is most rapid in the 4-10 keV range. The nitridation reaction process which differs from that of low-energy (< 1 keV) NC t.o n bombardment is explained in terms of ion implantation, physical sputtering, chemical reaction and radiation-enhanced diffusion of interstitial N atoms.