Quantitative SIMS analysis based on the “combined LTE-bond breaking” model

Abstract

A semi-theoretical model for quantitative SIMS analysis, which is based on the experimental results of secondary ion emission on the metallic surface exposed to oxygen, is discussed in this paper. The improvement upon the “combined LTE-bond breaking” idea comes from the fact that the ion yields of metallic elements will be enhanced by increasing oxygen pressure, but the enhancement for the metallic element with higher electronegativity is more remarkable. The amount of positive and negative secondary ions produced in bond breaking is not only determined by how many oxides are formed on the surface, but by how strong the oxide bonds are. If the bond breaking process is considered as an ionization process in which elemental ionization potentials are supposed to be lower than their normal values, and if both the amount of oxides and the bond strength are assumed to be functions of the electronegativity the theoretical equation of the positive secondary ion yield on the surface exposed to oxygen is obtained. In the equation, the quantity of exposure to oxygen and the elemental electronegativity are included. This quantitative method can be used under a wide range of oxygen pressure and some satisfactory analytical results have been obtained.