Characterization of quasi-breakdown in ultra-thin gate oxides in an automated test environment

A new oxide breakdown phenomenon termed quasi-breakdown (QB) has been reported in ultra-thin (< 5.0 nm) oxides. During constant voltage or current stress (TDDB) this oxide breakdown phenomenon is characterized as having a distinct transition from a low noise to a very high measurement noise mode. At the QB point only small voltage or current discontinuities may occur. If the stress is continued beyond the QB point catastrophic oxide failure eventually takes place. Post QB oxide current measurements typically show substantial increases over pre-stressed values but are well below catastrophic failure levels.