Liner- and barrier-free NiAl metallization: A perspective from TDDB reliability and interface status

This study reports the time-dependent-dielectric-breakdown (TDDB) reliability of NiAl on SiO2 without any barrier layer. NiAl was indicated to exhibit superior TDDB reliability in comparison to Cu/TaN in the time-to-failure (4200 s versus 240 s, at 4 MV/cm at 200 degrees C) and in the breakdown activation energy under 4 MV/cm (1.17 eV versus 0.87 eV). Moreover, NiAl was found to form an atomically thin and self-limiting Al oxide layer at the NiAl/SiO2 interface, and this Al oxide layer, together with the large cohesive energy of NiAl, was considered to be possible origin for the excellent reliability. The results demonstrate a great potential of NiAl as a liner-and barrier-free interconnect material.