High-temperature conduction behaviors of HfO_2/TaN-based metal-insulator-metal capacitors

摘要

High-temperature (～90-150℃) conduction mechanisms of metal-insulator-metal (MIM) capacitors with atomic-layer-deposited HfO_2 dielectric are studied. In the low field range, the Schottky emission current is dominant, and the deduced dielectric constant is close to the static one of HfO_2. In the high field range, the resulting leakage current complies with the Poole-Frenkel (PF) emission, which is demonstrated by the fact that the extracted dielectric constant equals the optical frequency one (i.e., square of refractive index) of HfO_2. The underlying mechanisms are disbussed based on carrier velocities under different electric fields. Further, the deduced Schottky barrier height is ～0.251-0.274 eV in the low field range, which relates to the contributions from high density traps in the HfO_2 film and the nonideal TaN/HfO_2 interface, etc. The extracted trap potential well depth for the PF effect is ～1.11-1.37 eV in the high field range.