Approach to Quantitative Evaluation of Electron-Induced Degradation of SiO2 Film Surface with Different Amounts of Carbon Contaminations

Abstract

Effects of carbon contaminations existing on the SiO2 film surface on the electron-induced damage of SiO2 were investigated. Carbon contaminations, the amount of which is only ∼0.05 nm thickness, are found to act as a protective layer for the degradation. The changes in the elemental and oxide Si-LVV Auger peak intensities due to the electron-induced damage are confirmed to be reasonably described by two-and one-step decomposition models, respectively. The critical dose, at which a certain amount of the damage occurs, is larger for the higher beam current density of primary electrons and the larger initial amount of carbon contaminations. The present results confirmed that the dependences of the degradation on the amount of carbon contaminations and the beam current density are attributed to the diffusion of oxygen and recombination of broken bonds between Si and oxygen, which are enhanced by the increase in the local temperature due to the electron irradiation. Consequently, the small amount of carbon contaminations was found to strongly affect results of the quantitative Auger electron spectroscopy analysis of metal oxides when the electron-induced damage of samples occurs. The present analytical approach, where the critical doses are measured for the SiO2 surfaces with different amounts of carbon contaminations, is effective to evaluating and estimating the electron-induced damage.