The recessed-gate IGBT structure

A recessed gate (RG) structure is presented for the IGBT and its characteristics are compared with DMOS and UMOS-IGBT for the first time. For the fabrication of the RG structure, it is not necessary to perform the difficult polysilicon planarization step required for the UMOS-IGBT. The breakdown voltage of the RG-IGBT is close to that of the DMOS-IGBT, even though it has a trench structure. The RG-IGBT has a lower on-state voltage drop when compared with the DMOS-IGBT because there is no JFET resistance. The parasitic thyristor latch-up current density of the RG-IGBT is higher than that of the DMOS-IGBT. In addition, the RG-IGBT has a wide forward bias SOA (FBSOA). The saturation current density of the RG-IGBT is lower than that of the UMOS-IGBT, leading to a superior short circuit SOA (SC-SOA).