Operation mechanism and performance optimization for a novel ultralow loss SOI LIGBT with high current capability

Abstract

In this paper, a novel ultralow on-state voltage-drop (V ON ) and high current capability SOI lateral insulated gate bipolar transistor (LIGBT) is proposed and investigated by simulation. The proposed device features a folded trench gate (FTG) and a step thickness (ST) drift region filled with insulator, named FTS LIGBT. The FTG is employed to increase the channel density and modulate the current distribution, achieving high current capability and reducing the V ON . The stepped insulator in drift region acts as the barrier to suppresses holes from being extracted by cathode and enhances the conductivity modulation, thus further contributes to an ultralow V ON in the on-state. Meanwhile, the drift region with varied thickness approximates the effect of variation of lateral doping (VLD) technique to optimize the electric-field distribution, and then maintains high breakdown voltage (BV ). Additionally, the T-shaped P+cathode region improves hole collection efficiency and vertical channels provide a low-resistance for hole current, and thus improves the latch-up immunity and short-circuit capability. Compared with the conventional LIGBT at the same turn-off loss (E OFF ), the V ON of the FTS LIGBT is reduced by 23% and 38% at the current density of 100 A cm −2 and 200 A cm −2 , respectively; The E OFF is reduced by 53% at the current density of 100 A cm −2 at the same V ON . The FTS exhibits high saturation current capability (751 A cm −2 ), which is 2.5 times as that of the conventional LIGBT.