• Baboux, Nicolas
• Romeo, Pédro Rojo
• Bouaziz, Jordan
• Vilquin, Bertrand

Abstract

Recently discovered, doped HfO2 [1] is a promising candidate for several ferroelectric applications. Among them, the most addressed are Negative-Capacitance Field Effect Transistor (NC-FET) and Ferroelectric Random Access Memory (FRAM). Compared to other materials, HfO2 processes have not only the advantage of being already integrated in Si CMOS industry, but also its ferroelectric properties are adequate for using oxide layer thinner than 10nm. Nevertheless, some of its properties should be improved for industrial applications. During cycling, the main issues are the limitation of the wake-up effect and the imprint, the fatigue and the endurance of the material. The ferroelectric phase (f-phase) has often been studied by Atomic Layer Deposition (ALD) [2]. However, most of the time the electrodes are made by Physical Vapor Deposition (PVD) processes, and industrial processes to separate Hf and Zr are usually expensive. It could be interesting to have only one process where the separation of Hf and Zr is not needed and where all depositions are made in the same machine. Furthermore, one of the most important benefit of sputtering is the deposition time which can be until 120 times faster than ALD depositions for the oxide layer. In this presentation, details will be given on how we succeeded in the deposition of ferroelectric hafnium/zirconium oxide (HZO) solid solutions by changing the pressure in the magnetron sputtering chamber in order to realize Metal/Insulator/Metal (MIM) capacitors. X-rays Diffraction (XRD), Transmission Electron Microscopy (TEM) and advanced electrical characterizations has been led to understand the difference between ferroelectric and non-ferroelectric samples. Two targets will be compared: a metallic Hf/Zr (56/44) target (reactive sputtering) and an oxide ZrO2/HfO2 (50/50) target (non-reactive sputtering). On these two targets, stoichiometry issues will be described and different fabrication tests have been led, such as: annealing at different temperatures, changing the size of the ferroelectric insulator layer, changing the size and the materials of the bottom and top electrodes, changing the oxygen flows, annealing with and without top electrodes. In each one of the studies, our understanding of the phenomena involved will be given.[1] T.S. Böscke, J. Müller, D. Bräuhaus, U. Schröder, U. Böttger, Ferroelectricity in hafnium oxide thin films, Appl. Phys. Lett. (2011).[2] M.H. Park, Y.H. Lee, H.J. Kim, Y.J. Kim, T. Moon, K. Do Kim, J. Müller, A. Kersch, U. Schroeder, T. Mikolajick, C.S. Hwang, Ferroelectricity and Antiferroelectricity of Doped Thin HfO2-Based Films, Adv. Mater. (2015)

Topics

• impedance spectroscopy
• phase
• x-ray diffraction
• thin film
• Oxygen
• reactive
• zirconium
• physical vapor deposition
• fatigue
• transmission electron microscopy
• annealing
• random
• field-effect transistor method
• hafnium
• atomic layer deposition
• hafnium oxide