Gate Oxide Reliability of SiC MOSFETs and Capacitors Fabricated on 150mm Wafers

Gate oxide reliability on silicon carbide MOSFETs and large-area SiC N-type capacitors was studied for devices fabricated on 150mm SiC substrates. Oxide lifetime was measured under accelerated stress conditions using constant-voltage time-dependent dielectric breakdown (TDDB) testing, or ramped-voltage breakdown (RBD) testing. TDDB results from 1200V Gen3 MOSFETs reveal a field acceleration parameter of about 35 nm/V, similar to values reported for SiO2 on silicon. Temperature-dependent RBD tests of large capacitors from 25°C to 200°C reveal an apparent activation energy of 0.24eV, indicating that oxide lifetime increases as the temperature is decreased, as expected. Using this acceleration parameter and activation energy in the linear field model, the gate oxide lifetime from MOSFET TDDB testing extrapolates to greater than 108 hours at a gate voltage of 15 VGS at 175°C.