Anti-Ferroelectric ZrO₂ Capacitors With Ultralow Operating Voltage (<1.2 V) and Improved Endurance Toward Logic Compatible eDRAM

Abstract

We have developed and experimentally demonstrated anti-ferroelectric (AFE) ZrO2 capacitors with operating voltage (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {op}}$ </tex-math></inline-formula>) lower than 1.2 V while maintaining sufficient memory window (MW) (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2{P}_{\text {r}}= \sim {20}~\mu $ </tex-math></inline-formula>C/cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}}$ </tex-math></inline-formula>), high endurance (projected to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{14}}$ </tex-math></inline-formula> cycles), and long data retention (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gt 10^{{4}}$ </tex-math></inline-formula> s at 85 °C). Such superior characteristics are enabled by ultra-scaled (6 nm) AFE ZrO2 with precisely controlled internal bias (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {int}}$ </tex-math></inline-formula>) and high remnant polarization (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {r}}$ </tex-math></inline-formula>) through process engineering including work function (WF) modulation of top electrode (TE), O3 treatment of bottom electrode (BE), and AlOx capping. The AFE capacitors demonstrated in this work enable the developing 1T1C AFeRAM with low-power and high-density toward logic-compatible eDRAM.