Dramatic reduction of gate leakage current in 1.61 4;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 4;nm equivalent oxide thickness (EOT) HfO2 dielectric the gate leakage current density can be reduce to approximately 10−7 4;A/cm2, which is nearly seven orders (107) in magnitude lower than that of using pure oxide with identical EOT.