Fully ALD-grown TiN/Hf0.5Zr0.5O2/TiN stacks: Ferroelectric and structural properties

Abstract

Since the discovery of ferroelectricity (FE) in HfO2-based thin films, they are gaining increasing attention as a viable alternative to conventional FE in the next generation of non-volatile memory devices. In order to further increase the density of elements in the integrated circuits, it is essential to adopt a three-dimensional design. Since atomic layer deposition (ALD) processes are extremely conformal, ALD is the favored approach in the production of 3D ferroelectric random access memory. Here, we report the fabrication of fully ALD-grown capacitors comprising a 10-nm-thick FE Hf0.5Zr0.5O2 layer sandwiched between TiN electrodes, which are subjected to a detailed investigation of the structural and functional properties. The robust FE properties of Hf0.5Zr0.5O2 films in capacitors are established by several alternative techniques. We demonstrate a good scalability of TiN/Hf0.5Zr0.5O2/TiN FE capacitors down to 100-nm size and the polarization retention in the test “one transistor-one capacitor” (1T-1C) cells after 1010 writing cycles. The presence of a non-centrosymmetric orthorhombic phase responsible for FE properties in the alloyed polycrystalline Hf0.5Zr0.5O2 films is established by transmission electron microscopy. Given the ability of the ALD technique to grow highly conformal films and multilayered structures, the obtained results indicate the route for the design of FE non-volatile memory devices in 3D integrated circuits.

Hf0.5Zr0.5O2-based ferroelectric memristor with multilevel storage potential and artificial synaptic plasticity

“…PPF operates as a sum of time applied to biological synapses. Reducing the time interval between two consecutive enhancement pulses increases the synaptic weight [16,19,49,50]. This simulates the process of learning and forgetting in biological synapses.…”

Atomic Layer Deposition of oriented nickel titanate (NiTiO3)

“…This feature has been exploited to make bottom and top electrodes (TiN) during deposition of a ferroelectric material (Hf0.5Zr0.5O2), thus producing a contacted sample ready for testing. [70] This also shows the capability of fabricating complete electrical components for integrated circuits, entirely by ALD.…”

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].…”