New voltage ramp dielectric breakdown methodology based on square root E model for Cu/low-k interconnect reliability

A new voltage ramp dielectric breakdown (VRDB) methodology based on square root (SQRT) E model for dielectrics reliability evaluation was developed. We conducted VRDB and time dependent dielectric breakdown (TDDB) experiments on dielectrics in Cu/low-k interconnect for reliability assessment. The experimental results show very good correlation between VRDB and TDDB data underlying SQRT E model. The electric field acceleration parameter of SQRT E model can be estimated with our methodology by applying dual ramping rate during VRDB test. Furthermore, we derived a relation to transform the shape factor of statistic distribution of VRDB breakdown voltage (Vbd) to shape factors expected for TDDB failure time distributions. As a result, our novel methodology allows to define a reliability criteria of VBD that is equivalent to meet a TDDB specification lifetime.