The Investigation of Reduced Variation Effect in FinFETs With Ultrathin 3-nm Ferroelectric Hf₀.₅Zr₀.₅O₂

In this work, the device-to-device variation of ferroelectric FinFETs (Fe-FinFET) is demonstrated experimentally by evaluating the threshold voltage ( <tex-math notation="LaTeX">VTH)</tex-math> variation of the devices with different Hf <tex-math notation="LaTeX">0.5</tex-math> Zr <tex-math notation="LaTeX">0.5</tex-math> O <tex-math notation="LaTeX">₂</tex-math> (HZO) thin films. Distinguished from the cognition that large variation caused by stochastic FE domains, the suppressed <tex-math notation="LaTeX">VTH</tex-math> variation results of the 3-nm HZO FinFETs than that of general FinFETs with HfO <tex-math notation="LaTeX">₂</tex-math> gate insulator are demonstrated first. Furthermore, for a larger sweeping gate voltage range ( <tex-math notation="LaTeX">V_GS,range)</tex-math> to ensure FE domain switching, the superior variation characteristics of devices with ultrathin 3-nm HZO film are achieved, regardless of ever-expected severe disturbances induced by ferroelectricity with a higher <tex-math notation="LaTeX">V_GS,range</tex-math> . A comprehensive analysis in distribution characteristics of <tex-math notation="LaTeX">VTH</tex-math> unveils an enhanced capacity for variation mitigation in Fe-FinFETs operating at lower voltage, which is demonstrated by a reduction of 28.9% in the standard deviation of <tex-math notation="LaTeX">VTH</tex-math> for 3-nm HZO FinFETs compared to 4-nm HfO <tex-math notation="LaTeX">₂</tex-math> FinFETs, specifically at <tex-math notation="LaTeX">V_GS,range</tex-math> of 0.6 V. To account for the phenomenon, a polarization-induced capacitance enhancement variation compensation theory is proposed coupling with film thickness-dependent FE variation. This work provides the guidelines for mitigating the variation to build reliable large-scale integrated circuits based on FE devices.