Transistor with voltage clamp

摘要

A power transistor takes advantage of the lower breakdown voltage capability of a spherical junction. A clamping region (40) having a spherical shape is provided in the gate region of an enclosed transistor cell (42). The clamping region (40) has a lower breakdown voltage than do the active portions of the transistor cell (42). Both a DMOSFET and an IGBT transistor may be provided with the clamping region (40) (a MOS-controlled thyristor is also disclosed). The clamping region (40) is a zener diode in the case of the DMOSFET, and is a bipolar junction transistor in the case of the insulated gate bipolar transistor. The clamping region (40) is preferably an island in the center of each cell of a closed cell structure.