A fast and soft recovery diode with ultra small Qrr (USQ-Diode) using local lifetime control by He ion irradiation

This paper presents an ultra small reverse recovery charge Qrr diode (USQ-Diode) for Insulated Gate Bipolar Transistor (IGBT) modules. The USQ-Diode has a thin p-layer anode with low impurity concentrations, p+ stripe anodes, and lifetime control by He ion irradiation. By employing the thin p-layer anode, the injection of holes into the n-layer as minority carriers was significantly reduced near the pn junction. By using the He ion irradiation, crystal defects for lifetime control were localized near the pn junction. With the combined effects from both the reduced injection of holes and the local lifetime control by the He ion irradiation, as compared to the conventional pn diode, the USQ-Diode realized such superior characteristics as 1/5 times smaller reverse recovery charge and 0.2 V lower forward voltage drop.