Highly Scaled InGaZnO Ferroelectric Field-Effect Transistors and Ternary Content-Addressable Memory
Chen Sun, Kaizhen Han, Subhranu Samanta, Qiwen Kong, Jishen Zhang, Haiwen Xu, Xinke Wang, Annie Kumar, Chengkuan Wang, Zijie Zheng, Xunzhao Yin, Kai Ni, Xiao Gong
Abstract
We demonstrate nonvolatile and area-efficient ternary content-addressable memories (TCAMs) featuring amorphous indium–gallium–zinc–oxide (a-IGZO) ferroelectric field-effect transistors (FeFETs) with excellent electrical characteristics. An extremely large sensing margin of the TCAM array is achieved due to the large current ON/OFF 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 the a-IGZO FeFETs. Our Hf <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> Zr <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text {1-x}}\text{O}$ </tex-math></inline-formula> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (HZO)-based a-IGZO FeFETs have a metal–ferroelectric–metal–insulator–semiconductor (MFMIS) structure. By engineering the area ratio of the ferroelectric layer ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${A}_{Fe}$ </tex-math></inline-formula> ) and the metal–oxide–semiconductor layer ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${A}_{MOS}$ </tex-math></inline-formula> ), a large memory window (MW) of 2.9 V is realized. Reliability test results, including retention, endurance, and positive bias temperature instability, show long-term retention of more than ten years and high endurance of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> cycles. In addition, by scaling the channel length down to 40 nm, ON current of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$77 ~\mu \text{A}/ \mu \text{m}$ </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">${V}_{\mathrm{GS}} - {V}_{\mathrm{TH}}$ </tex-math></inline-formula> = 5 V and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\mathrm{DS}}$ </tex-math></inline-formula> = 2 V) and <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 more than eight orders can be obtained for the ultrascaled a-IGZO FeFETs while maintaining an MW of 2.8 V.