Physics-Based Strategies for Fast TDDB Testing and Lifetime Estimation in SiC Power MOSFETs

To expedite testing, time-dependent dielectric breakdown (TDDB) analyses are conducted on commercial 4H-SiC
mosfet
s at high gate-to-source voltages (
$\bm {V_{GS}}$
), under Fowler–Nordheim conduction only. However, as inferred, such conditions induce impact ionization-generated holes in the dielectric layer (SiO
$\bm {_{2}}$
), resulting in a state transition in the effective dipolar moment. This accelerates the SiO
$\bm {_{2}}$
degradation leading to an overestimation of its intrinsic lifetime at typical
$V_{GS}$
values for gate driving in power converters. To address this, a physics-based approach is proposed to design TDDB tests under such conditions and to correct the intrinsic lifetime prediction at nominal
$\bm {V_{GS}}$
values, shortening the testing time by up to two orders of magnitude. Thus, the proposed method is a well-suited candidate to be considered in SiC power device qualification standards, still under development.