Dramatic reduction of gate leakage current in 1.61 nm HfO2 high-k dielectric poly-silicon gate with Al2O3 capping layer

The electrical properties of poly-silicon gate MOS capacitors with HfO₂ gate dielectric, with and without Al₂O₃ capping layer, were investigated. Without the capping layer, the experimental results show that an unacceptably high gate leakage current due to the interaction between HfO₂ and poly-silicon was observed; while with a thin Al₂O₃ layer capping on 1.61 nm equivalent oxide thickness (EOT) HfO₂ dielectric, the gate leakage current density can be reduce to approximately 10^-7 A/cm₂, which is nearly seven orders (10⁷) in magnitude lower than that of using pure oxide with identical EOT