Effect of barrier layer on the electrical and reliability characteristics of high-k gate dielectric films

Electrical and reliability characteristics of several metal/high-k/(barrier layer)/Si capacitor structures have been investigated. The equivalent oxide thickness (EOT) increased as the annealing temperature increased, especially in oxygen ambient. Jet vapor-deposited (JVD) nitride was found to be a good oxidation barrier which is important for achieving thin EOT. Introducing TiO2 as a barrier layer reduced the leakage current and EOT of Pt/PST/Si capacitor. The conduction mechanism in Pt/TiO2/Si structure was found to be tunneling-like behavior limited by the interfacial layer. Hysteresis could be minimized by the optimization of the annealing process. In reliability characteristics, TiO2 revealed no significant degradation and exhibited better wear-out properties than conventional SiO2.