AES analysis of nitridation of Si(100) by 2-10 keV N+ 2 ion beams

Abstract

Ion beam nitridation of Si(100) as a function of N+ 2 ion energy in the range of 2-10 keV has been investigated by in-situ Auger electron spectroscopy (AES) analysis and Ar+ depth profiling. The AES measurements show that the nitride films formed by 4-10 keV N+ 2 ion bombardment are relatively uniform and have a composition of near stoichiometric silicon nitride (Si3N4), but that formed by 2 keV N+ 2 ion bombardment is N-rich on the film surface. Formation of the surface N-rich film by 2 keV N+ 2 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) N+ 2 ion bombardment is explained in terms of ion implantation, physical sputtering, chemical reaction and radiation-enhanced diffusion of interstitial N atoms.