Summary form only given. Mechanisms of high-field electrical breakdown have been widely investigated in recent years in thermally grown silicon dioxide films at fields larger than 7 MV/cm. For oxide films thicker than 10 nm it was found that constant-voltage and constant-current tests produce breakdown by different mechanisms. The fast breakdown of constant-voltage tests is explained by the IIR (impact-ionization-recombination) breakdown model, which attributes it to the growth of positive charge at the cathode at fields larger than a critical field. The slow breakdown of constant-current tests cannot be explained by the IIR model, since growth of electron trapping during a test keeps increasing the critical field. Breakdown on constant-current tests is attributed to the effects of the generation of a large density of trap states at the injection barrier, which can grow to 10/sup 19//cm/sup 3/. Such change in the oxide can produce current instability by diverse processes.
展开▼
