The Investigation of Reduced Variation Effect in FinFETs With Ultrathin 3-nm Ferroelectric Hf $_{\text{0}.\text{5}}$ Zr $_{\text{0}.\text{5}}$ O $_{\text{2}}$

In this work, the device-to-device variation of ferroelectric FinFETs (Fe-FinFET) is demonstrated experimentally by evaluating the threshold voltage ( $\textit{V}_{\text{TH}}\text{)}$ variation of the devices with different Hf $_{\text{0}.\text{5}}$ Zr $_{\text{0}.\text{5}}$ O $_{\text{2}}$ (HZO) thin films. Distinguished from the cognition that large variation caused by stochastic FE domains, the suppressed $\textit{V}_{\text{TH}}$ variation results of the 3-nm HZO FinFETs than that of general FinFETs with HfO $_{\text{2}}$ gate insulator are demonstrated first. Furthermore, for a larger sweeping gate voltage range ( $\textit{V}_{\text{GS,\textit{rang}\textit{e}}}\text{)}$ 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 $\textit{V}_{\text{GS,\textit{rang}\textit{e}}}$ . A comprehensive analysis in distribution characteristics of $\textit{V}_{\text{TH}}$ 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 $\textit{V}_{\text{TH}}$ for 3-nm HZO FinFETs compared to 4-nm HfO $_{\text{2}}$ FinFETs, specifically at $\textit{V}_{\text{GS,\textit{rang}\textit{e}}}$ 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.