SIO2 DEGRADATION WITH CHARGE INJECTION POLARITY

We have investigated gate oxide degradation in metal-oxide-semiconduct or (MOS) devices as a function of high-field constant-current stress f or charge injection from both gate and substrate. The two polarities a re asymmetric: gate injection, where the substrate Si-SiO2 interface i s the collecting electrode for the energetic electrons, shows a higher rate of interface-state generation (DELTAD(it)) and lower charge-to-b reakdown Q(bd). Thus the collecting electrode interface, which suffers primary damage, emerges as a critical degradation site in addition to the injecting electrode interface, which has been the traditional foc us. Consistent with a physical-damage model of breakdown, we demonstra te that interfacial degradation is an important precursor of breakdown , and that the nature of breakdown-related damage is physical, such as trap-generation by broken bonds.