Characteristics of Ni/Gd FUSI for NMOS gate electrode applications

ArticleinIEEE Electron Device Letters 28(7):555 - 557 · August 2007with6 Reads
Impact Factor: 2.75 · 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 HfSiO<sub>x</sub> 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.