Great impact of RFC technology on fast recovery diode towards 600 V for low loss and high dynamic ruggedness

Abstract

In the fast recovery operation of Free-wheeling Diode (FWD), to reduce voltage surge “snap-off”, we propose the Relaxed Field of Cathode (RFC)-planar anode diode in the range of 600 V to 1700 V. RFC effect is described by the parallel connection of pin diode and pnp transistor in as a single chip solution. Its structure is realized by our thin wafer process technology utilizing the backside lithography to make p/n alternating pattern after thining the wafer. As the result, our RFC diode up to 1700 V has the following three advantages comparing with the conventional one: (a) 40% lower recovery loss (EREC), 30% lower forward voltage drop (VF), (b) a large recovery Safe Operating Area (SOA) with the high peak power density of 1.4W/cm2 and (c) easiness to adjust a lower crosspoint below rated current density in the output I-V. Therefore, the proposed RFC diode has a great potential as the next generation Si FWD in the all voltage range.