Local Epitaxial Templating Effects in Ferroelectric and Antiferroelectric ZrO₂

Abstract

Nanoscale polycrystalline thin-film heterostructures are central to microelectronics, for example, metals used as interconnects and high-K oxides used in dynamic random-access memories (DRAMs). The polycrystalline microstructure and overall functional response therein are often dominated by the underlying substrate or layer, which, however, is poorly understood due to the difficulty of characterizing microstructural correlations at a statistically meaningful scale. Here, an automated, high-throughput method, based on the nanobeam electron diffraction technique, is introduced to investigate orientational relations and correlations between crystallinity of materials in polycrystalline heterostructures over a length scale of microns, containing several hundred individual grains. This technique is employed to perform an atomic-scale investigation of the prevalent near-coincident site epitaxy in nanocrystalline ZrO2 heterostructures, the workhorse system in DRAM technology. The power of this analysis is demonstrated by answering a puzzling question: why does polycrystalline ZrO2 transform dramatically from being antiferroelectric on polycrystalline TiN/Si to ferroelectric on amorphous SiO2/Si?

Interface-engineered ferroelectricity of epitaxial Hf0.5Zr0.5O2 thin films

“…However, up to date, most of the HZO thin films studied were polycrystalline, which contained secondary non-ferroelectric phases that suppressed the ferroelectric properties and obscured the understanding of the fundamental physics of ferroelectric HZO 17,33,34 . It was demonstrated that the ferroelectric orthorhombic phase can be stabilized in epitaxial HZO films grown on a perovskite substrate [35][36][37][38][39][40][41] . Notably, it was found that the La 0.67 Sr 0.33 MnO 3 (LSMO) buffer layer is essential in the epitaxial growth of ferroelectric HZO 18,19,36,42 .…”

Giant energy storage ultrafast microsupercapacitors via negative capacitance superlattices

“…2c, Extended Data Fig. 4), while also underscoring the important role of amorphous templating in HZO antiferroelectric-ferroelectric phase stability 52,53 .…”

Improving the Synaptic Behavior with Polar Orthorhombic Phase in Hf0.5Zr0.5O2 Film

“…Figure d–f show the in-plane particle size distribution of the film at these three annealing rates. When performing particle size statistics, it is sensible to separately analyze the sizes of particles of m-phase and o-phase and compare them . Further discussion on the particle size of o-phase and m-phase can be found in Figures S6–S7.…”

“…Figure S5 demonstrates the significant influence of the oxygen pressure on the interplanar spacing of the orthorhombic phase. The relationship between the interplanar spacing of d o-HZO(111) and p indicates that as the deposition pressure increases from 1 to 15 Pa, the interplanar spacing of d o-HZO decreases from approximately 2.977 to 2.945 Å (by 46 Further discussion on the particle size of o-phase and m-phase can be found in Figures S6−S7. Figure 2d shows that the particle size in the film with the 5 °C/min cooling rate is scattered and distributes in a quite wide range of 6−26 nm; Figure 2e−f show that the particle size becomes smaller and distributes in a narrower range with the increase of annealing rate.…”