Explorative Study of a Novel Desaturation IGBT with Transconductance Modulation

Based on the Micro Pattern Trench (MPT) technology, we reduced the distance,
$d$
, between the main gate (G1) and the desaturation gate (G2) within an IGBT cell. We observed that if
$d$
is longer, the G2 voltage,
$V_{\mathrm{G}2}$
, has almost no impact on the transfer characteristics as long as it stays below the threshold voltage. This behavior is consistent with earlier research. However, for very short
$d$
we found a modulation of the transconductance. Our study explains the effect of this modulation, shows how it can be used to improve turn-off desaturation, and how it impacts the IGBT's turn-on behavior through both TCAD simulation and demonstrator chips. A comparison with conventional single-gate IGBTs and SiC MOSFETs has revealed the high potential of desaturation IGBTs. This is also underlined by RB-SOA test results.