MICROAREA ELEMENTAL MAPPING USING GALLIUM FOCUSED ION-BEAM-INDUCED AUGER ELECTRONS

It is known that the ion-induced Auger electron (IAE) spectra of light elements, such as Mg, Al and Si, show considerably different characte ristics from those of the conventional electron-induced Auger spectra. The Auger decay of excited species induced by energetic projectiles i s generally explained by the formation of instantaneous quasi-molecule s consisting of a projectile and a target atom, and two target atoms r espectively. Through crossing of the molecular orbitals, inner-shell v acancies are produced. An IAE spectrum comprises a continuous backgrou nd related to the decay of excited atoms/ions in the solid (bulk-like peak) and discrete sharp peaks (atomic-like peak). These sharp peaks o riginate from excited species which are sputtered into the vacuum thro ugh ion bombardment. We studied Ga-FIB-induced Auger emission from Al and Si using an ion and electron dual focused beam apparatus developed by our group. It has been shown that the LMM Auger yields and the sig nal-to-background ratios are much higher than those of electron-induce d ones, and increase linearly with the increment of the incident energ y of the Ga FIB. Combining these features with the Ga FIB technique, w e developed a two-dimensional elemental mapping method with sub-mu m l ateral resolution using Ga FIB IAE.