Improved understanding of an electron beam charge compensation method for magnetic sector secondary ion mass spectrometer analysis of insulators

Abstract

Good charge compensation has historically been difficult to achieve for secondary ion mass spectrometry positive secondary ion depth profile analysis of highly insulating samples using a magnetic sector secondary ion mass spectrometer. A new charge compensation method has been developed utilizing an adjacent electron beam approach. A combination of computational simulation and quantitative characterization of the charge compensation phenomenon was used to elucidate the underlying mechanisms of this charge compensation technique with the goal of further improving this method. Results of this approach show that a low intensity electron shower consisting of secondary and backscattered electrons resulting from the impact of the primary electron beam with elements in the electron beam flight path may be responsible for charge compensation. It is also determined that the charge compensation provided by the adjacent impact technique can be further improved to provide better profile stability, higher mass resolution, and higher detection sensitivity by removing the conductive metal coating immediately adjacent to the sputtered area. Analysis of electron beam sensitive materials is also possible using this improved method.