Time-Dependent Dielectric Breakdown of Gate Oxide on 4H-SiC with Different Oxidation and Isolation Processes

Effects of NO annealing and isolation structure on the time-dependent dielectric breakdown of gate oxide is studied. NO annealing can reduce the interface state density effectively but the nitrogen in oxide bulk degrades the electric field of 10-year TDDB by 1 MV/cm. LOCOSiC isolation also degrades the electric field by 0.3 MV/cm. The breakdown positions of the LOCOSiC isolation sample distribute along the periphery of the isolation because the gate oxide grown on the Ar ion implantation induced damaged zone is poor. Fortunately, the TDDB degradation due to LOCOSiC process is not sever and the 10-year TDDB electric field of ~6 MV/cm is acceptable in most applications.