Nanosecond Polarization Switching and Long Retention in a Novel MFIS-FET Based on Ferroelectric $\hbox{HfO}_{2}$

Abstract

We report the fabrication of completely CMOScompatible ferroelectric field-effect transistors (FETs) by stabilization of a ferroelectric phase in 10-nm-thin Si : HfO 2 . The program and erase operation of this metal-ferroelectric-insulatorsilicon FET (MFIS) with poly-Si/TiN/Si : HfO 2 /SiO 2 /Si gate stack is compared to the transient switching behavior of a TiN-based metal-ferroelectric-metal (MFM) capacitor. Polarization reversal in the MFM capacitor follows a characteristic time and field dependence for ferroelectric domain switching, leading to a higher switching speed with increasing applied field. Similar observations were made for the material when implemented into an MFIS structure. Nonvolatile switching was observed down to 20-ns pulsewidth, yielding a memory window (MW) of 1.2 V. Further increase in gate bias or pulsewidth led to charge injection and degradation of the MW. Retention measurements for up to 10 6 s suggest a retention of more than ten years. Index Terms-Hafnium oxide, metal-ferroelectric-insulatorsemiconductor (MFIS) FET, nonvolatile memory.

The origin of ferroelectricity in Hf1−xZrxO2: A computational investigation and a surface energy model

“…Furthermore, ferroelectricity was found in the 9 nm mixed oxide thin film Hf0.5Zr0.5O2 (HZO) 2 deposited on TiN electrodes, although neither the pure HfO2 nor the pure ZrO2 film exhibit ferroelectricity. The existence of a true ferroelectric effect has been confirmed by various experiments such as P-V and C-V measurements 8 as well as retention extrapolated up to 10 years 12 and the occurrence of orthorhombic peaks in XRD measurements 13 . ZrO2 was also studied extensively in the context of functional thin films since its tetragonally stabilized form has a high dielectric constant.…”

Inductive crystallization effect of atomic-layer-deposited Hf0.5Zr0.5O2 films for ferroelectric application

“…Because of a high Schottky barrier formed in the contact between the HfO 2-based thin film and the Ni electrode, lesser intrinsic leakage current has been secured and enforced the optimization of retention of the MIM capacitor. In addition to the contact characteristic, appropriate bias voltage and residual injected interface charge can also improve the data retention significantly [12].…”

Switching Dynamics and Hot Atom Damage in Landau Switches

“…In this study, we will use the recently discovered dopedHfO2 as the FE material [10], [12], [14]. The Landau coefficients α = −8.66×10 8 (C −2 Jm) and β = 1.93×10 10 (C −4 Jm 5 ) are derived based on the approach in [19] using experimentally reported values of coercive field E c = 1 × 10 8 (Vm −1 ) and saturation polarization of P s = 0.3 (Cm −2 ) [12].…”

“…If this atomic transition is too slow, FE Landau switches would be irrelevant for highspeed logic operation, even if I on is high. Now, experiments do show that nanosecond regime switching can be achieved in hysteretic FE memories [12]- [14] at voltages higher than the coercive voltage (V > V c ). However, FE Landau switch operates at ∼ V c /10 and the voltage drop inside the FE is opposite to externally applied voltage [2]- [10] resulting in electric field inside FE which is opposite to the direction of polarization switching.…”

“…However, FE Landau switch operates at ∼ V c /10 and the voltage drop inside the FE is opposite to externally applied voltage [2]- [10] resulting in electric field inside FE which is opposite to the direction of polarization switching. Since switching time in FE depends strongly on voltage [14] and is only possible in the same direction of electric field inside FE for bistable hysteretic (BH) mode used in FE-memory [12]- [15], it is unclear if sufficiently fast switching can ever be achieved in Landau switches.…”