As-grown donor-like traps in low-k dielectrics and their impact on intrinsic TDDB reliability
Highly porous low-k dielectrics are essential for downscaling of the interconnects for 2010nm technologies. A planar capacitor test vehicle was used to investigate the intrinsic time dependent dielectric breakdown (TDDB) reliability of low-k dielectrics and the origin of an observed CV hysteresis was studied. We hypothesize that the hysteresis is caused by donor-like traps present in the bulk of the low-k but not by electron/hole trapping or mobile charges. It is proposed that porogen/carbon residues are the source of these donor-like traps. Using Ileak vs. time measurements, it was found that the donor-like traps accelerate the dielectric degradation due to an enhanced EOX, causing a localized partial breakdown. The intrinsic TDDB reliability of the low-k film was improved by adding a sealing layer as such layer blocked the donor-like traps discharging.
donor-like trap low-k tddb cv hysteresis beol reliability