Hysteresis-Free Gate-All-Around Stacked Poly-Si Nanosheet Channel Ferroelectric Hf<sub>x</sub>Zr<sub>1-x</sub>O<sub>2</sub> Negative Capacitance FETs With Internal Metal Gate and NH<sub>3</sub> Plasma Nitridation
Chia‐Chin Lee, Dong‐Ru Hsieh, Shouwei Li, Yi-Shan Kuo, Tien‐Sheng Chao
Abstract
In this study, hysteresis-free double-layer gate-all-around stacked poly-Si nanosheet channel ferroelectric Hf <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> Zr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> negative capacitance field-effect transistors (DL GAA NS FE-HZO NC-FETs) with an internal metal gate (IMG) and NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> plasma nitridation were experimentally investigated and comprehensively discussed for the first time. The results revealed that NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> plasma nitridation at both the ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /TiN and TiN/HZO interfaces can effectively enhance the HZO ferroelectricity and quality by suppressing the generation of oxygen vacancies ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{o}{)}$ </tex-math></inline-formula> . Furthermore, the SiON interfacial layer quality can be enhanced by passivating bulk defects within the SiON interfacial layer through NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> plasma nitridation at the ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /TiN interface. When NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> plasma nitridation is performed at both the ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /TiN and TiN/HZO interfaces, the devices exhibit excellent electrical characteristics: 1) an extremely low subthreshold swing (SS) of 45.77 mV/decade; 2) an ultrasteep average SS (ASS) of 61.39 mV/decade; 3) a relatively high ON/OFF current ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{ \mathrm{\scriptscriptstyle ON}} / {I}_{ \mathrm{\scriptscriptstyle OFF}}{)}$ </tex-math></inline-formula> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ > 5\,\,\times \,\,10^{{7}}$ </tex-math></inline-formula> ; and 4) a quite high effective breakdown voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {EBD}}$ </tex-math></inline-formula> ) of 6.7 V at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{D}$ </tex-math></inline-formula> = 0.1 V. Thus, these devices are promising candidates for low-power-consumption monolithic 3-D integrated circuit (IC) applications.