The IGBT Device

3.2. Symmetric IGBT Structure

The structure for the symmetric blocking, double-diffused, IGBT was shown on the left-hand side of Fig. 2.1. A symmetric blocking, trench-gate, IGBT structure is similar to that shown in Fig. 2.4 without the N-buffer layer. The analyses and design procedures described below are applicable to both of these gate structures. The first symmetric blocking IGBT was demonstrated in 1982 [2]. Since the development of IGBT products was mainly focused on motor drive circuits operated from a DC power bus, the symmetric structure lay dormant for nearly 20 years because the asymmetric IGBT structure has much more favorable characteristics for motor drive applications. Interest in the symmetric IGBT structure has revived for application ...