(CD-5) TDDB breakdown of th-SiO2 on 4H-SiC: 3D SEM failure analysis

We analyzed SiO₂ void volumes formed on samples which failed during TDDB tests by constructing three-dimensional (3D) images in FIB-SEM system. We succeeded in visualizing the breakdown spots within SiO₂ on 4H-SiC substrates and provided clear evidence of the influence of SiO₂ void volume on 4H-SiC TDDB failure (ex. Tbd or Rbd). The small SiO₂ voids play a very important role in the degradation of TDDB reliability. The present 3D SEM technique applied to th-SiO₂ on 4H-SiC can be very useful in the investigation of TDDB failure mechanism.