A new MOS-gate bipolar transistor for power switches

A new monolithic integrated power device, the MOS-gate transistor (MGT), which consists of a bipolar transistor for an output stage and two MOSFET's for a driver stage, has been investigated. The purpose of the study was to obtain a power switch having characteristics of an easy drive, a short turn-off time, and a high current density. The developed device structure featured the integration of three elements into a small cell from a large number of which the MGT chip was constructed. This device had no parasitic thyristor, making it free from the latchup phenomenon. Unit MGT devices with a blocking voltage of 400-500 V were fabricated. A high current density of 90 A/cm²at a collector-emitter voltage of 2 V and a short turn-off time of less than 1 µs were obtained. The MGT devices, which contained 36 cells, were fabricated with chip sizes of 5 × 5 mm. They exhibited a blocking voltage of 500 V, on-state voltage of 2.3 V at a current of 10 A, and turn-off time of 0.5 µs at 150°C.