Strategies for Reducing Operating Voltage of Ferroelectric Hafnia by Decreasing Coercive Field and Film Thickness

Abstract

As the AI era advances, there has been increasing interest in the next-generation memory capable of low-power operation as well as high performance. HfO₂-based ferroelectric random-access memory (FeRAM) has been extensively studied for its simple structure similar to that of dynamic random-access memory (DRAM) and high power efficiency. However, due to the limited endurance of HfO₂ and the high coercive field (E_c) arising from its high energy barrier for polarization switching, the commercialization of the low-power FeRAM faces several challenges. To address these issues, this perspective reviews current scientific approaches and experimental advances aimed at achieving low voltage switching in ferroelectric HfO₂ thin films by reducing either E_c or film thickness. Key strategies including controlling types and number of dopants in HfO₂, decreasing free energy of the intermediate tetragonal phase, achieving metal-excess rhombohedral phase, controlling oxygen vacancy concentration, and enhancing domain wall motion are reviewed based on theory as well as experimental demonstrations. Especially, recent progress in achieving low voltage operation in ferroelectric HfO₂ capacitors via sub-5 nm thickness scaling are highlighted. Overall, the importance of precise material and process control to overcome current technical limitations in device scalability and reliability is emphasized, casting an optimistic outlook on the future of ferroelectric memory technology.