AES analysis of silicon nitride formation by 10 keV N+ and N+ 2 ion implantation

Abstract

Reactions of N+ and N+ 2 ions with the Si(100) surface as a function of ion dose and angle of incidence by 10 keV N+ and N+ 2 bombardment have been studied by in situ Auger electron spectroscopy (AES) analysis. The AES measurements show that a continued exposure of the ion beam to a saturation dose of > 5 × 1016 N+ 2/cm2 leads to a surface stoichiometry close to that of Si3N4. Complete nitridation, i.e, the formation of Si3N4, could be achieved at incident angles between 0° and 30° to the surface normal. At incident angles exceeding 30°, the degree of nitridation decreases. Above 60° incident angle, no nitride was found in the near-surface region. A simplified model has been proposed to explain the observed angular dependence. The samples with higher ion doses were also examined by ex situ scanning electron microscopy (SEM). No blister or bubble was found on the surface suggesting that under saturation conditions the self-sputtering of captured nitrogen atoms near the surface by further incoming projectiles is the major contributor to nitrogen removal in our experiment. No pronounced difference between N+ and N+ 2 bombardment was observed in this experiment. Copyright © 1996 Elsevier Science Ltd.