Impacts of Zr Composition in \hbox \hbox\hbox 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 Hf 1-x Zr x O y (0 ≤ x ≤ 1) gate-dielectric films are examined. n-Channel metal-oxide-semiconductor field-effect transistor (nMOSFET) devices with ZrO 2 gate dielectrics showed a much smaller V th shift under the positive bias stress compared with the same device with HfO 2 gate dielectrics. The impact of Zr composition on the crystallization temperature, crystalline phases, and surface morphology of Hf 1-x Zr x O y films is studied. As the Zr composition in the Hf 1-x Zr x O y 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 ZrO 2 film is much smaller than that of crystallized HfO 2 . The Hatband voltage (V fb ) shift under positive gate-bias stress in p-channel MOS capacitor (pMOSCAP) devices show a similar trend to the Vth shift in nMOSFET devices. In addition, the annealed ZrO 2 films show a large reduction in the V fb , shift under the positive bias stress compared with as-deposited ZrO 2 in pMOSCAP devices. The improved bias-temperature-instability characteristics of ZrO 2 compared with that of HfO 2 is related to the smaller grain size of crystallized ZrO 2 .