12.5 kV SiC Gate Turn Off Thyristor With Trench-Modulated JTE Structure

In this article, an ultrahigh voltage silicon carbide (SiC) gate turn off (GTO) Thyristor with a novel trench-modulated two-zone junction termination extension (TM-TZ-JTE) is investigated through TCAD simulations and experimental fabrications. Bevel trench rings are included in each JTE to achieve a smooth decrease of the effective JTE dose from the inner side to outer side of the termination, which significantly increases the tolerance window to the both vertical and horizontal etching process variations without increasing the total number of lithography masks. TCAD simulations indicate that the tolerance window of TM-TZ-JTE to the interface charges is over two times larger than that of the conventional TZ-JTE. Experimental measurements demonstrate that the device could achieve a breakdown voltage (BV) of 12.5 kV at a leakage current of
$1 \mu \text{A}$
. The voltage drop on unit termination length is the highest among the reported terminations for SiC GTOs, which is preferred for improving the power density. The differential ON-resistance at a current density of 100 A/cm
²
is 7.91
$\text{m}\Omega \cdot $
cm
²
. The current rising and falling time under inductive switching test are 1.5 and
$2.3 \mu \text{s}$
, respectively. Finally, the bipolar degradation due to the N
⁺
implantation is evaluated. After 10-h accelerating test, only slight degradation of forward voltage drop is observed.