Fast-Switching-Speed, Low-Forward-Voltage-Drop Static Induction(SI) Thyristor.

Abstract

An SI thyristor using a normally-off planar-gate structure in a low power class has been developed for the use as a power switching device in a three-phase inverter circuit. A 600V-15A class SI thyristor with very fast switching time (tgt, tgq) and low forward voltage drop (VTM) was designed and fabricated. This design was performed with a reasonable wafer structure (n-/n/p+), an n- base carrier concentration and thickness, and a gate structure (gate diffusion length and gate pitch). Microscopic processing was used to obtain this SI thyristor. The performance trade-off between turn-off time and forward voltage drop is controlled by a life time control process using proton irradiation which results in a very fast switching time with tgt of 500ns and tgq of 500ns with VTM of 1.5V (at IT=18A). At the current level of IT=18A, the current density in the active area becomes 200A/cm2 which indicates that the performance of the SI thyristor is superior to that of conventional IGBTs and MOSFETs.