A 13 kV 4H-SiC n-Channel IGBT with Low R_diff,onand Fast Switching

Abstract

For the first time, high power 4H-SiC n-IGBTs have been demonstrated with 13 kV blocking and a low Rdiff,on of 22 mWcm2 which surpasses the 4H-SiC material limit for unipolar devices. Normally-off operation and >10 kV blocking is maintained up to 200oC base plate temperature. The on-state resistance has a slight positive temperature coefficient which makes the n-IGBT attractive for parallel configurations. MOS characterization reveals a low net positive fixed charge density in the oxide and a low interface trap density near the conduction band which produces a 3 V threshold and a peak channel mobility of 18 cm2/Vs in the lateral MOSFET test structure. Finally, encouraging device yields of 64% in the on-state and 27% in the blocking indicate that the 4H-SiC n-IGBT may eventually become a viable power device technology.

Introduction

“…capability were reported in 2007 [41] followed by 13-kV devices in 2009 [42]. It is anticipated that SiC IGBTs with voltage ratings of 15e20 kV will be developed within a few years.…”

IGBT Structural Design

“…Based upon available information about the properties of silicon carbide, a BFOM of about 2000 is predicted for the 4H-SiC polytype [19]. Asymmetric n-Channel SiC IGBTs were subsequently developed [33] with blocking voltage of 13 kV. These devices are now commercially available from several companies [27e29].…”

SiC bipolar devices for high power and integrated drivers

“…P-type substrates are not available in large dimensions and production volumes and they also introduce high resistance in series to the device. Recently 13 kV, 22 mΩcm 2 n-IGBT have been reported [35]. This device shows conductivity modulation during forward conduction that corresponds to higher current capability compared to a 10kV SiC DMOSFET.…”