Hydrogen depth profiling and multi-energy proton implantation: SIMS as a tool for implant process control

Proton implantation offers a versatile means to introduce in-depth structural modifications into crystalline targets. Remarkable effects on the electrical properties of silicon, including n-type doping and charge carrier lifetime reduction, have been reported and find application in silicon-based power device engineering. Characterisation of these implants implies quantitative determination of hydrogen and Secondary Ion Mass Spectrometry (SIMS) stands for the most effective analytical tool to accomplish this task. However, successful SIMS depth profiling of low dose deep proton implants requires careful optimisation of operating conditions, and implementation of SIMS for implant process control purposes remains challenging. In this study, n-type silicon substrates are implanted with 400–1200 keV protons, at low to medium doses, in the form of single and multi-energy implants. Precise SIMS hydrogen depth profiling exceeding 20 μm in depth with limits of detection (LOD) down to 3e16 cm−3 in optimised operating conditions is demonstrated. The utility of SIMS as metrology tool for proton implant analysis is then examined through practical applications such as ion implanting system monitoring and coupling with Spreading Resistance Profiling (SRP) for doping monitoring purposes.