Factors Influencing Secondary Ion Yields

Abstract

Secondary ion mass spectrometry is the most sensitive analytical technique for surface and thin film elemental characterization. Each element of the periodic table has a certain probability for forming either a positive or negative ion as it is ejected from the surface of a bombarded solid. The large flux of ions typically produced (∼10⁸-10¹² ions/sec), coupled with the net efficiency of an ion probe for extracting, mass analyzing and detecting these ions (∼0.01%) gives SIMS its exceptional sensitivities. It is the purpose of this report to provide a general overview of the physical processes governing secondary ionization and how these processes influence the quantitative interpretation of ion intensities.