Ultra high voltage IGBTs in 4H-SiC

Abstract

A 1 cm × 1 cm 4H-SiC N-IGBT exhibited a blocking voltage of 20.7 kV with a leakage current of 140 μA, which represents the highest blocking voltage reported from an MOS semiconductor power switching device to date. The device showed a V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</sub> of 6.4 V at an I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> of 20 A, and a differential R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on,sp</sub> of 28 mΩ-cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Temperature insensitive on-state characteristics were demonstrated. Switching measurements with a supply voltage of 8 kV were performed, and a turn-off time of 720 ns and a turn-off loss of 5.4 mJ were measured at 25°C, for a 8.4 mm × 8.4 mm device with 140 μm drift layer and 5 μm Field Stop buffer layer. It was demonstrated that the charge injection from the backside can be controlled by varying the thickness of the Field-Stop buffer layer. A 55 kW, 1.7 kV to 7 kV boost converter operating at 5 kHz was demonstrated using the 4H-SiC N-IGBT, and an efficiency value of 97.8% was reported.