MOS Characteristics of Ta-Mo Alloy Electrodes on a ZrO2 Gate Dielectric

Metal-oxide-semiconductor (MOS) capacitors were fabricated to reveal the electrical and the chemical properties of Ta-Mo alloy gate electrodes on ZrO2. The work function of the alloy varied between 4.1 eV and 4.7 eV as the co-sputtering powers of Ta and Mo were changed. Good thermal stability up to 800 ℃ was observed for the alloy with a 90.2 % Ta atomic composition and the extracted work function was 4.1 eV, which is compatible with NMOS applications, but the pure Ta gate electrode exhibited very poor thermal stability; the equivalent oxide thickness (EOT) of the tantalum-gated MOS capacitor decreased drastically after 600 ℃ annealing. The barrier heights between the alloy electrode and the gate dielectric were calculated using a Fowler-Nordheim analysis. Based on the experimental results, the metal alloy with about 90 % Ta and 10 % Mo may be an excellent gate electrode on ZrO2 for NMOS devices. Metal-oxide-semiconductor (MOS) capacitors were fabricated to reveal the electrical and the chemical properties of Ta-Mo alloy gate electrodes on ZrO2. The work function of the alloy varied between 4.1 eV and 4.7 eV as the co-sputtering powers of Ta and Mo were changed. Good thermal stability up to 800 ℃ was observed for the alloy with a 90.2 % Ta atomic composition and the extracted work function was 4.1 eV, which is compatible with NMOS applications, but the pure Ta gate electrode exhibited very poor thermal stability; the equivalent oxide thickness (EOT) of the tantalum-gated MOS capacitor decreased drastically after 600 ℃ annealing. The barrier heights between the alloy electrode and the gate dielectric were calculated using a Fowler-Nordheim analysis. Based on the experimental results, the metal alloy with about 90 % Ta and 10 % Mo may be an excellent gate electrode on ZrO2 for NMOS devices. KCI Citation Count: 2