AES and SAM microanalysis of structure ceramics by thinning and coating the backside

The preparation of thin specimens from bulk ceramic materials and coating t he reverse side of the specimens with conductive material was used effectiv ely to minimize the charging effects on ceramic surfaces during AES and Sca nning Auger Microscopy (SAM) analysis. The technique allowed AES and SAM an alysis to be carried out with analysis areas of a few tens of nanometres in size. The decrease of surface charging by this technique results from the transition of a primary electron beam interaction volume (V-A) from an insu lating region (V-I) to the conductive coating region (V-c) after thinning o f the specimens. This reduces the number of electrons remaining in the insu lating region and thus surface charging is reduced. Three structure ceramic bulk materials were prepared using this thinning technique and analysed by high-energy resolution AES and SAM: (Y, La)-doped silicon nitride; Dy-dope d Sialon; and alumina composite reinforced with silicon carbide whiskers. I t is observed clearly in the grains of silicon nitride and the Sialon syste m that the kinetic energies of Si LVV and Si KLL shift to 84 and 1613 eV, r espectively, and Si LW is shifted further to similar to 80 eV in the interg ranular phases of the silicon nitride system as the nitrogen atoms are repl aced by oxygen to produce N-Si-O bonding. Nitrogen was detected at the inte rfaces of alumina and the silicon carbide whiskers. The difference and dist ribution of composition in solid solution phases and intergranular phases a re shown also in the SAM images and AES spectra. Copyright (C) 2001 John Wi ley & Sons, Ltd.