A Complementary Metal Oxide Semiconductor Process-Compatible Ferroelectric Tunnel Junction

Abstract

In recent years, experimental demonstration of ferroelectric tunnel junctions (FTJ) based on perovskite tunnel barriers has been reported. However, integrating these perovskite materials into conventional silicon memory technology remains challenging due to their lack of compatibility with the complementary metal oxide semiconductor process (CMOS). This communication reports the fabrication of an FTJ based on a CMOS-compatible tunnel barrier HfZrO (6 unit cells thick) on an equally CMOS-compatible TiN electrode. Analysis of the FTJ by grazing angle incidence X-ray diffraction confirmed the formation of the noncentrosymmetric orthorhombic phase (Pbc2, ferroelectric phase). The FTJ characterization is followed by the reconstruction of the electrostatic potential profile in the as-grown TiN/HfZrO/Pt heterostructure. A direct tunneling current model across a trapezoidal barrier was used to correlate the electronic and electrical properties of our FTJ devices. The good agreement between the experimental and theoretical model attests to the tunneling electroresistance effect (TER) in our FTJ device. A TER ratio of ∼15 was calculated for the present FTJ device at low read voltage (+0.2 V). This study suggests that HfZrO is a promising candidate for integration into conventional Si memory technology.

Magnetoelectric Effect at the Ni/HfO2 Interface Induced by Ferroelectric Polarization

“…The direct experimental evidence of the ferroelectric Pca2 1 phase was provided by scanning transmission electron microscopy [26]. These findings stimulated significant efforts in studying relevant properties of ferroelectric HfO 2 films [27][28][29][30][31][32], showing their applicability as a functional gate oxide in nanoscale FeFET memory devices [33,34] and ferroelectric tunnel junctions [35][36][37].…”

CMOS Compatible Hf0.5Zr0.5O2 Ferroelectric Tunnel Junctions for Neuromorphic Devices

“…This mode of conduction is given by the WKB model, which describes one dimensional, direct tunneling over a trapezoidal potential barrier . The polarization‐dependent interface potentials are taken from Ambriz vargas and coworkers, yielding current densities for the LRS and HRS state. The linear combination with grain fraction g in LRS then readswhere j ( g ) is the current density from a fraction g of the grains oriented toward the low‐resistive state.…”

“…Furthermore, to ensure analog large‐scale integration, artificial neuromorphic systems need to be compatible with complementary metal oxide semiconductor (CMOS) technology. A CMOS‐compatible FTJ exploiting hafnium zirconium oxide (Hf 0.5 Zr 0.5 O 2 ) as the ferroelectric layer was reported earlier . Hf 0.5 Zr 0.5 O 2 has the advantage of crystallizing at low temperature, compatible with the CMOS process, while displaying ferroelectricity at very low thicknesses due to the presence of an orthorhombic phase .…”

Recent advances, perspectives, and challenges in ferroelectric synapses*

“…Quantity of HfO2-based FTJs spring up [32][33][34][35][36] . The CMOS-compatible HfO2-based FTJs are considered as practical candidate of ferroelectric synapses [36,65,66] .…”