Impacts of Zr Composition in [Formula Omitted] Gate Dielectrics on Their Crystallization Behavior and Bias-Temperature-Instability Characteristics

The effects of Zr composition on the crystallization behaviors and reliability characteristics of atomic-layer-deposited [Formula Omitted] gate-dielectric films are examined. n-Channel metal-oxide-semiconductor field-effect transistor (nMOSFET) devices with [Formula Omitted] gate dielectrics showed a much smaller [Formula Omitted] shift under the positive bias stress compared with the same device with [Formula Omitted] gate dielectrics. The impact of Zr composition on the crystallization temperature, crystalline phases, and surface morphology of [Formula Omitted] films is studied. As the Zr composition in the [Formula Omitted] films increased, the reduction of crystallization temperature and the transformation from a monoclinic to a tetragonal phase were observed. The grain size of the crystallized [Formula Omitted] film is much smaller than that of crystallized [Formula Omitted]. The flatband voltage [Formula Omitted] shift under positive gate-bias stress in p-channel MOS capacitor (pMOSCAP) devices show a similar trend to the [Formula Omitted] shift in nMOSFET devices. In addition, the annealed [Formula Omitted] films show a large reduction in the [Formula Omitted] shift under the positive bias stress compared with as-deposited [Formula Omitted] in pMOSCAP devices. The improved bias-temperature-instability characteristics of [Formula Omitted] compared with that of [Formula Omitted] is related to the smaller grain size of crystallized [Formula Omitted].