Zirconium-doped Hafnium Oxide Based Ferroelectric Materials for Memory Applications

Download or read book Zirconium-doped Hafnium Oxide Based Ferroelectric Materials for Memory Applications written by Fei Huang (Researcher in electrical engineering) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As data processing and storage needs continue to grow at a rapid pace, the development of innovative memory technologies is crucial. The discovery of ferroelectricity in hafnia (HfO2)-based materials has garnered significant attention in both academia and industry, owing to their potential to revolutionize non-volatile memory (NVM) technology and enable novel computing architectures. HfO2-based ferroelectric materials offer advantages over conventional perovskite oxides, such as low-temperature synthesis and conformal growth in three-dimensional structures on silicon, making them compatible with complementary metal-oxide-semiconductor (CMOS) technology and ideal for device scaling. However, several challenges still exist for implementing ferroelectric HfO2 in commercial products, such as polarization variation during cycling (wake-up effect), high operation voltage, compatibility with back-end-of-line (BEOL) processing temperatures, and low memory density. In this dissertation, I tackled the challenges outlined above. I began by focusing on the Hf0.5Zr0.5O2 (HZO) material itself and addressing the wake-up effect through the introduction of an HfO2 buffer layer at the HZO/electrode interface. Subsequently, I developed a new measurement setup capable of directly measuring individual nm-sized devices, which enabled investigating the scaling effect in HZO-based ferroelectric capacitors. Through my research, I was able to demonstrate excellent ferroelectricity and reliability in ultra-thin HZO (4 nm) capacitors with molybdenum (Mo) electrodes. These capacitors exhibited low operation voltage, wake-up-free behavior, high endurance, and low RTA temperatures, making them highly desirable for practical applications. I also studied the size scaling effect down to 65 nm × 45 nm devices, where I observed ultra-high remanent polarization (2Pr) for the first time at this scale. In addition to exploring two-dimensional scaling to improve density, I also proposed a hybrid structure for 4 bits/cell storage, increasing the multi-bit capability in a single cell.