Nanolaminate and Solid Solution Antiferroelectric Zirconia-Based Films Prepared by Atomic Layer Deposition for Energy Storage Capacitors

In recent years, the rapid emergence of electronic devices with high power efficiencies for Internet of Things and Big Data applications is creating a great demand for ultracompact and miniaturized energy storage components. Among currently available energy storage devices, dielectric capacitors are highly desirable owing to their high-power density, all solid state, high operating voltage, and long operating life [1]. The insulators of such dielectric capacitors are enhanced high-k materials including non-linear dielectrics in the form of ferroelectrics and antiferroelectrics (AFE). The observation of AFE-like properties in ultrathin zirconia-based at the nanoscale have attracted particular attention as promising replacement for conventional perovskites for use in high-performance energy storage capacitors [2]. Herein, we present a comparative study between nanolaminate and solid solution of zirconia and hafnium-based materials, deposited using Atomic Layer Deposition (ALD) technique, to understand whether it is a promising candidate for insulator use for AFE dielectric capacitors. We investigate the electrical performance using metal-insulator-metal planar capacitors structures consisting of TiN/ AFE HfO 2 -ZrO 2 /TiN (stack thickness 15nm/6 to 10nm/15nm). The collected results (X-ray reflectometry XRR, wavelength dispersive X-ray fluorescence WDXRF, HRTEM images and X-ray diffraction) highlight the perfect tuning of hafnium-zirconia content released using nanolaminate as well as solid ALD approaches. Overall, an increased thermal annealing process (from 400°C to 600°C) significantly enhances the AFE property of 6-10nm HfO 2 -ZrO 2 ultrathin layers, evidenced by the enhancement in energy storage density ESD (20-30 J.cm -3 ). The ZrO 2 dosing in a relatively high proportion (>80%) on the AFE HfO 2 -ZrO 2 solid solution yields well antiferroelectricity at 400°C annealing temperature, attributed to the promotion of AFE phase formation. Indeed, the increasing of ZrO 2 amount in the composition of HfO 2 -ZrO 2 allows a higher tetragonal phase in comparison to orthorhombic phase. The ALD solid solution approach meets the stringent requirement of BEOL integration. Furthermore, the ESD and the efficiency exhibit robust thermal stability in 300-450 K temperature range in addition to an excellent endurance up to 10 7 of charge/discharge cycling at 3MV.cm -1 . However, as the RTA temperature progressed up to 600°C, the AFE HfO 2 -ZrO 2 nanolaminate exhibits superiority over AFE HfO 2 -ZrO 2 solid solutions in terms of ESD values (up to 20%). Indeed, the intercalation of ultrathin HfO 2 layers (<1nm) on the construction of 10nm HfO 2 -ZrO 2 stack is likely to improve AFE properties in comparison to reference 10nm-ZrO 2 layers or solid solution.