Jung Minhyun, Gaddam Venkateswarlu, Jeon Sanghun
School of Electrical Engineering, Korea Advanced Institute of Science & Technology, 34141, Daejeon, Republic of Korea.
Nano Converg. 2022 Oct 1;9(1):44. doi: 10.1186/s40580-022-00333-7.
In the present hyper-scaling era, memory technology is advancing owing to the demand for high-performance computing and storage devices. As a result, continuous work on conventional semiconductor-process-compatible ferroelectric memory devices such as ferroelectric field-effect transistors, ferroelectric random-access memory, and dynamic random-access memory (DRAM) cell capacitors is ongoing. To operate high-performance computing devices, high-density, high-speed, and reliable memory devices such as DRAMs are required. Consequently, considerable attention has been devoted to the enhanced high dielectric constant and reduced equivalent oxide thickness (EOT) of DRAM cell capacitors. The advancement of ferroelectric hafnia has enabled the development of various devices, such as ferroelectric memories, piezoelectric sensors, and energy harvesters. Therefore, in this review, we focus the morphotropic phase boundary (MPB) between ferroelectric orthorhombic and tetragonal phases, where we can achieve a high dielectric constant and thereby reduce the EOT. We also present the role of the MPB in perovskite and fluorite structures as well as the history of the MPB phase. We also address the different approaches for achieving the MPB phase in a hafnia material system. Subsequently, we review the critical issues in DRAM technology using hafnia materials. Finally, we present various applications of the hafnia material system near the MPB, such as memory, sensors, and energy harvesters.
在当前的超缩放时代，由于对高性能计算和存储设备的需求，存储器技术正在不断进步。因此，诸如铁电场效应晶体管、铁电随机存取存储器和动态随机存取存储器（DRAM）单元电容器等传统半导体工艺兼容的铁电存储器设备的相关研究仍在持续进行。为了运行高性能计算设备，需要诸如DRAM之类的高密度、高速且可靠的存储器设备。因此，DRAM单元电容器的高介电常数和降低的等效氧化物厚度（EOT）受到了广泛关注。铁电氧化铪的发展推动了各种器件的开发，如铁电存储器、压电传感器和能量收集器。因此，在本综述中，我们聚焦于铁电正交相和四方相之间的准同型相界（MPB），在此处我们可以实现高介电常数，从而降低EOT。我们还介绍了MPB在钙钛矿和萤石结构中的作用以及MPB相的历史。我们还探讨了在氧化铪材料体系中实现MPB相的不同方法。随后，我们回顾了使用氧化铪材料的DRAM技术中的关键问题。最后，我们展示了MPB附近氧化铪材料体系的各种应用，如存储器、传感器和能量收集器。
