Experimental Demonstration of Stacked Gate- All-Around Poly-Si Nanowires Negative Capacitance FETs With Internal Gate Featuring Seed Layer and Free of Post-Metal Annealing Process

Abstract

For the first time, two-layer stacked nanowire gate-all-around (GAA) negative capacitance (NC) field-effect transistors (FETs) with an ultrasmall poly-Si channel that has a size of $5.3\times9$ nm(2) and a metal-ferroelectric-metal-insulator-semiconductor (MFMIS) are experimentally demonstrated. FETs exhibit a remarkable I-on-I-off ratio of more than 10(8). We demonstrated stacked channels, double layers, GAA NC-FET with a threshold voltage ( ${V}_{\textit {TH}}$ ) of 0.61 V, and a superior subthreshold behavior with an average and minimum sub- ${V}_{\textit {TH}}$ slope of 43.85 and 26.84 mV/dec, respectively. An additional ZrO2 seed layer was inserted under the Hf $_{{1-}{x}}$ ZrxO2 layer to improve ferroelectric crystallinity. Thus, the conventional crystallization annealing step can be omitted due to the presence of the orthorhombic phase ( ${o}$ -phase) before further post-metal annealing (PMA).