Innovative Ge–SiO2 bonding based on an intermediate ultra-thin silicon layer

• Published in: Journal of materials science. Materials in electronics 2017-07, Vol.28 (14), p.10262-10269
• Main Authors: Mao, Danfeng, Ke, Shaoying, Lai, Shumei, Ruan, Yujiao, Huang, Donglin, Lin, Shaoming, Chen, Songyan, Li, Cheng, Wang, Jianyuan, Huang, Wei
• Format: Article
• Language: English
• Subjects: Ammonium hydroxide; Annealing; Bonding strength; Characterization and Evaluation of Materials; Chemical vapor deposition; Chemistry and Materials Science; Covalent bonds; Germanium; Germanium oxides; High vacuum; Materials Science; Optical and Electronic Materials; Organic chemistry; Oxidation; Silicon dioxide
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-017-6793-x

Low temperature Ge to SiO 2 wafer bonding based on an intermediate ultra-thin Si layer (1 nm) which is grown on the Ge wafer (Si/Ge) by ultra-high vacuum chemical vapor deposition (UHV/CVD) system is demonstrated in this work. The formation and decomposition of the unstable GeO x layer are effectively restrained due to the incomplete oxidation of the covered ultra-thin Si layer after deposition. Therefore, a nearly voids-free bonding interface is observed after post annealing. The hydrophilicity of Si/Ge wafer surface is higher than that of the Ge wafer surface after the treatment of the diluted NH 4 OH solution. The more –OH groups on the Si/Ge wafer surface than that on the Ge wafer surface can be responsible for this feature. As a result, the high bonding strength of 4.39 MPa for the Ge/Si–SiO 2 wafer pairs was achieved due to the formation of more covalent bonds (Si–O–Si) at the bonding interface after post annealing.