Highly Scaled InGaZnO Ferroelectric Field-Effect Transistors and Ternary Content-Addressable Memory

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.