A Comparison of Voltage Ramp and Time Dependent Dielectric Breakdown Tests for Evaluation of 45nm Low-k SiCOH Reliability

A comparison of the relationship between voltage ramp dielectric breakdown (VRDB) test and constant-voltage time-dependent dielectric breakdown (TDDB) stress has been performed as part of a 45 nm low-k SiCOH reliability evaluation. Although some correlation was observed between VRDB and TDDB, it was found that the fast VRDB test can't replace TDDB to evaluate true long-term time-dependent behavior, which is important for reliability qualification. However, with the combination of VRDB and TDDB, a more comprehensive reliability assessment of low- k dielectric breakdown could be achieved. Finally, a novel, non-destructive spacing determination methodology is proposed and an excellent agreement between the extracted spacing and measured spacing is demonstrated.