Liu An-Chen, Tu Po-Tsung, Langpoklakpam Catherine, Huang Yu-Wen, Chang Ya-Ting, Tzou An-Jye, Hsu Lung-Hsing, Lin Chun-Hsiung, Kuo Hao-Chung, Chang Edward Yi
Department of Photonics, Institute of Electro-Optical Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan.
Industrial Technology Research Institute, No. 195, Sec. 4, Chung Hsing Rd., Chutung, Hsinchu 31040, Taiwan.
Micromachines (Basel). 2021 Jun 23;12(7):737. doi: 10.3390/mi12070737.
GaN has been widely used to develop devices for high-power and high-frequency applications owing to its higher breakdown voltage and high electron saturation velocity. The GaN HEMT radio frequency (RF) power amplifier is the first commercialized product which is fabricated using the conventional Au-based III-V device manufacturing process. In recent years, owing to the increased applications in power electronics, and expanded applications in RF and millimeter-wave (mmW) power amplifiers for 5G mobile communications, the development of high-volume production techniques derived from CMOS technology for GaN electronic devices has become highly demanded. In this article, we will review the history and principles of each unit process for conventional HEMT technology with Au-based metallization schemes, including epitaxy, ohmic contact, and Schottky metal gate technology. The evolution and status of CMOS-compatible Au-less process technology will then be described and discussed. In particular, novel process techniques such as regrown ohmic layers and metal-insulator-semiconductor (MIS) gates are illustrated. New enhancement-mode device technology based on the p-GaN gate is also reviewed. The vertical GaN device is a new direction of development for devices used in high-power applications, and we will also highlight the key features of such kind of device technology.
由于氮化镓（GaN）具有更高的击穿电压和高电子饱和速度，它已被广泛用于开发高功率和高频应用的器件。GaN高电子迁移率晶体管（HEMT）射频（RF）功率放大器是首个采用传统基于金的III-V族器件制造工艺制造的商业化产品。近年来，由于在电力电子领域的应用增加，以及在用于5G移动通信的射频和毫米波（mmW）功率放大器中的应用扩展，源自CMOS技术的用于GaN电子器件的大批量生产技术的开发需求大增。在本文中，我们将回顾采用基于金的金属化方案的传统HEMT技术的每个单元工艺的历史和原理，包括外延、欧姆接触和肖特基金属栅技术。然后将描述和讨论CMOS兼容的无金工艺技术的发展和现状。特别地，将说明诸如再生长欧姆层和金属-绝缘体-半导体（MIS）栅等新颖工艺技术。还将回顾基于p-GaN栅的新型增强型器件技术。垂直GaN器件是高功率应用器件的一个新的发展方向，我们也将突出此类器件技术的关键特性。
