Zhang Wenting, Zhang Caorui, Wu Junmin, Yang Fei, An Yunlai, Hu Fangjing, Fan Ji
State Key Laboratory of Advanced Power Transmission Technology, Global Energy Interconnection Research Institute Co., Ltd., Beijing 102209, China.
MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China.
Micromachines (Basel). 2021 Dec 17;12(12):1575. doi: 10.3390/mi12121575.
SiC direct bonding using O plasma activation is investigated in this work. SiC substrate and n SiC epitaxy growth layer are activated with an optimized duration of 60s and power of the oxygen ion beam source at 20 W. After O plasma activation, both the SiC substrate and SiC epitaxy growth layer present a sufficient hydrophilic surface for bonding. The two 4-inch wafers are prebonded at room temperature followed by an annealing process in an atmospheric N ambient for 3 h at 300 °C. The scanning results obtained by C-mode scanning acoustic microscopy (C-SAM) shows a high bonding uniformity. The bonding strength of 1473 mJ/m is achieved. The bonding mechanisms are investigated through interface analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Oxygen is found between the two interfaces, which indicates Si-O and C-O are formed at the bonding interface. However, a C-rich area is also detected at the bonding interface, which reveals the formation of C-C bonds in the activated SiC surface layer. These results show the potential of low cost and efficient surface activation method for SiC direct bonding for ultrahigh-voltage devices applications.
本文研究了利用氧等离子体活化进行碳化硅（SiC）直接键合。采用优化的60秒持续时间和20瓦的氧离子束源功率对SiC衬底和n型SiC外延生长层进行活化。经过氧等离子体活化后，SiC衬底和SiC外延生长层均呈现出足够的亲水性表面用于键合。将两片4英寸晶圆在室温下预键合，然后在大气氮气环境中于300℃退火3小时。通过C模式扫描声学显微镜（C-SAM）获得的扫描结果显示出高键合均匀性。实现了1473 mJ/m的键合强度。通过透射电子显微镜（TEM）和能量色散X射线光谱（EDX）进行界面分析来研究键合机制。在两个界面之间发现了氧，这表明在键合界面处形成了Si-O和C-O键。然而，在键合界面处还检测到一个富碳区域，这揭示了在活化的SiC表面层中形成了C-C键。这些结果表明了这种低成本、高效的表面活化方法在超高压器件应用的SiC直接键合方面的潜力。
