3-D simulation of heavy-ion induced charge collection in SiGe HBTs

This paper presents the first 3-D simulation of heavy-ion induced charge collection in a SiGe HBT, together with microbeam testing data. The charge collected by the terminals is a strong function of the ion striking position. The sensitive area of charge collection for each terminal is identified based on analysis of the device structure and simulation results. For a normal strike between the deep trench edges, most of the electrons and holes are collected by the collector and substrate terminals, respectively. For an ion strike between the shallow trench edges surrounding the emitter, the base collects appreciable amount of charge. Emitter collects negligible amount of charge. Good agreement is achieved between the experimental and simulated data. Problems encountered with mesh generation and charge collection simulation are also discussed.