AUGER PARAMETER DETERMINATION OF BONDING STATES ON THINLY OXIDIZED SILICON-NITRIDE

Silicon nitride powders have been thermally oxidized between 700 and 1 200 degrees C in a high-purity N-2-20% O-2 gas environment, The powder s were subsequently analyzed by x-ray photoelectron and Anger electron spectroscopies for evidence of oxynitride surface states, Measurement s were made on the Si 2p, O 1s, N 1s, C 1s, F 1s and Si KLL transition s, the latter being obtained using bremsstrahlung radiation from the M g x-ray source, As a function of increasing temperature the data show a clear progression of spectral binding energies and peak shapes that are indicative of more advanced surface oxidation. However, definitive analysis of these data rests on the combined use of both Auger and ph otoelectron data to define the oxidized surface states for a system th at involves two electrically insulating end states: silicon nitride an d silicon dioxide, Curve fitting the Si 2p and Si I(LL transitions as a function of oxidation, coupled with tbe use of Auger parameters for the starting silicon nitride and final silicon dioxide, reveals no mea surable evidence for an interphase oxynitride in the thin oxide scales of this study where the silicon nitride substrate is detectable. Poss ible incorrect assignment of oxynitride bonding, from shifted Si 2p st ates in the carbon referenced spectra, is attributable to band bending as the transition is made from incipient to fully formed silicon diox ide, (C) 1998 John Wiley & Sons, Ltd.