Characteristics of Ni/Gd FUSI for NMOS Gate Electrode Applications

North Carolina State Univ., Raleigh
IEEE Electron Device Letters (Impact Factor: 3.02). 08/2007; DOI: 10.1109/LED.2007.897889
Source: IEEE Xplore

ABSTRACT This letter investigates the work function tuning of nickel/gadolinium (Ni/Gd) fully silicided (FUSI) gate electrodes on HfSiOx dielectrics. It was found that as the percentage of Gd in the Ni/Gd increased from 10% to 30%, the effective work function value after a one-step 450-degC FUSI anneal decreased from 4.75 to 4.35 eV. In addition, the presence of Gd also resulted in lowering of equivalent oxide thickness (EOT) values. The mechanism for a decreased EOT is attributed to the reduction of low-kappa interfacial layers by the presence of Gd in the gate stack. The decrease in work function is attributed to the creation of oxygen vacancies within the high-kappa layer created by the presence of Gd layer.

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