Time-dependent dielectric breakdown of SiC-CMOS technology for harsh environments

Abstract

To estimate the failure time of silicon carbide (SiC) integrated circuits in harsh environments, the activation energy (Ea) and field acceleration factor of SiC n-channel MOS (nMOS) and p-channel MOS (pMOS) were measured using time-dependent dielectric breakdown testing at constant voltage stress in the range of 25–350 °C. Ea around 300 °C was 0.7 eV for nMOS and 0.66 eV for pMOS, which was about twice as high as that below 150 °C and did not differ greatly depending on the conductivity type. The gate dielectric breakdown mechanism shifted from the 1/E model to the E model as the temperature rose, and this is thought to have caused the Ea to change. The field acceleration factor in the E model at 300 °C was 2.7 and 2.3 cm/MV for nMOS and pMOS, respectively. The maximum operating electric fields of nMOS and pMOS for a 100-year lifetime are 6.8 and −7.2 MV/cm, which are over 25% lower than the fields at room temperature, mainly due to a shift in the dominant breakdown model. A more conservative failure time design will be required for SiC-ICs exposed to high temperatures.