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 (
${V}_{\text {TH}}{)}$
variation of the devices with different Hf
$_{{0}.{5}}$
Zr{0}.{5}O{2} (HZO) thin films. Distinguished from the cognition that large variation caused by stochastic FE domains, the suppressed
${V}_{\text {TH}}$
variation results of the 3-nm HZO FinFETs than that of general FinFETs with HfO2 gate insulator are demonstrated first. Furthermore, for a larger sweeping gate voltage range (
${V}_{\mathrm {GS,\mathit {rang}{e}}}{)}$
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
${V}_{\mathrm {GS,\mathit {rang}{e}}}$
. A comprehensive analysis in distribution characteristics of
${V}_{\text {TH}}$
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
${V}_{\text {TH}}$
for 3-nm HZO FinFETs compared to 4-nm HfO2 FinFETs, specifically at
${V}_{\mathrm {GS,\mathit {rang}{e}}}$
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.