Electrical characterisation and reliability of HfO_2 and Al_2O_3―HfO_2 MIM capacitors

摘要

Current leakage and breakdown of MIM capacitors using HfO_2 and Al_2O_3―HfO_2 stacked layers were studied. Conduction in devices based upon HfO_2 layers thinner than 8 nm is probably dominated by tunnelling. Al_2O_3― HfO_2 stacked layers provide a limited benefit only in term of breakdown field. Constant-voltage wear-out of samples using insulating layer thicker than 6 nm is dominated by a very fast increase of the leakage current. A two step mechanism involving the generation of a conduction path followed by a destructive thermal effect is proposed to explain breakdown mechanism.