Ferroelectric and Anti-Ferroelectric Hafnium Zirconium Oxide: Scaling Limit, Switching Speed and Record High Polarization Density

Abstract

The ferroelectric (FE) and anti-ferroelectric (AFE) properties of hafuium zirconium oxide (HZO) are investigated systematically down to 3 nm. The ferroelectric polarization, switching speed and the impact of atomic layer deposited (ALD) tungsten nitride (WN) electrodes are studied. Record high remnant polarization <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\text{P}_{r})$</tex> , on FE HZO and record high saturation polarization <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\text{P}_{s})$</tex> on AFE HZO are achieved with WN electrodes, especially in ultrathin sub-10 nm regime. A high dielectric constant of 30.4 is achieved on AFE HZO. The polarization switching speed of FE and AFE HZO, associated with C-V frequency dispersion, are also studied. For the first time, it is found polarization switching speed is faster in AFE HZO than FE HZO, suggesting AFE-FET could be more promising for high speed memory devices.