Analysis of Negative Capacitance Effect in Sub-3-nm Forksheet FETs

Forksheet (FSH) field-effect transistors (FETs) have the potential to continue scaling beyond the 3-nm technology node. Here, we present a comprehensive analysis of the performance of hysteresis-free negative capacitance (NC)-FSH FET with a metal-ferroelectric–metal-insulator–semiconductor (MFMIS) structure. Adding a ferroelectric (FE) layer into the gate-stack of a conventional FSH FET can significantly boost device performance, enabling lower subthreshold swing (SS), higher on-current-to-<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small>-current (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {ON}}$ </tex-math></inline-formula>/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {OFF}}$ </tex-math></inline-formula>) ratio, lower threshold voltage (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula>), higher transconductance (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${g}_{\text {m}}$ </tex-math></inline-formula>), and faster switching. Device characteristics are obtained by combining the solutions of the 1-D Landau-Khalatnikov (L-K) equation with fully calibrated 3-D technology computer-aided design (TCAD) simulations. The proposed NC-FSH FET exhibits, on average, a ~3.46% increase in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {ON}}$ </tex-math></inline-formula>/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {OFF}}$ </tex-math></inline-formula> ratio, ~19.2% faster switching, and ~63% reduction in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> compared to the baseline FSH FET. Furthermore, the NC-FSH FET achieves an SS as low as 29.76 mV/decade, which is a ~62% reduction from its baseline counterpart. Results also show the superiority of NC-FSH FET over NC-nanosheet (NSH) FET in terms of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {ON}}$ </tex-math></inline-formula>/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {OFF}}$ </tex-math></inline-formula> ratio and SS. Overall, introducing the NC effect in FSH FETs can add considerable power and performance benefits, while overcoming the scaling challenges associated with 3 nm and beyond manufacturing nodes.