Ni–Al–O diffusion barrier layer for high-κ metal-oxide-semiconductor capacitor

Using amorphous Ni–Al–O (a-Ni–Al–O) thin film as the intermediate layer, poly-crystalline Er2O3 thin film was grown on a-Ni–Al–O/Si (p-type) via laser molecular beam epitaxy, forming the Er2O3/Ni–Al–O gate stack. It was found that the mean dielectric constant of the Er2O3/Ni–Al–O gate stack with an equivalent oxide thickness of 1.5 nm is about 17–23, the interfacial states density is about 3.16 × 1012 cm−2 and the stack gate leakage current density is as small as 4.1 × 10− 6 A/cm2. Furthermore, The insertion of the Ni–Al–O thin film between the Er2O3 gate dielectric and p-Si substrate prevents the oxygen from being out-diffused, which significantly improved the stability of gate stack, showing that the Er2O3/Ni–Al–O gate stack thin film could be used as an ideal gate oxide layer for the future Metal Oxide Semiconductor Field Effect Transistors.