Secondary Ion Mass Spectrometry, SIMS

Abstract

Secondary ion mass spectrometry (SIMS) is based on the ejection of charged atomic and molecular species from the surface of a solid sample when it is bombarded by a stream of heavy particles. J. J. Thomson1 first observed this phenomenon in 1910. Later Arnot and Milligan2 investigated the secondary ion emission resulting from positive ion bombardment. Herzog and Viehboeck3 provided the basis of modern SIMS instrumentation, using an electron impact primary ion source in 1949. Other pioneers in the field constructed their own unique SIMS instruments.4, 5, 6, 7 The first commercial system derived from Herzog’s work8 was intended for the geochemical analysis of extraterrestrial material captured during the early years of outer space exploration. Since that time, SIMS has become an indispensable tool for the characterization and analysis of semiconductor components and materials. Its ability to detect all elements in the periodic table, excellent elemental sensitivity and inherent depth profiling capabilities make SIMS the appropriate choice for a number of critical semiconductor analysis needs. Dopant profiling, mobile ion monitoring, process contamination diagnosis, thin film characterization, interface analysis and surface analysis are just a few of the areas where SIMS can contribute to the root cause determination of microelectronics failures. In addition to the utilization of SIMS as a tool for the diagnosis of failures, the technique is a very powerful aid in the optimization of semiconductor processes, preventing failures. Typical applications in this preventive mode include the evaluation of the effectiveness of cleaning processes, monitoring the impact of new processing tools on wafer contamination levels and implant matching studies for technology transfer between fabrication sites.