Electrical properties of Si/Si bonded wafers based on an amorphous Ge interlayer Project supported by the National Natural Science Foundation of China (Nos. 61534005, 61474081)

• Published in: Journal of semiconductors 2018-11, Vol.39 (11)
• Main Authors: Lin, Shaoming, Ke, Shaoying, Ye, Yujie, Huang, Donglin, Wu, Jinyong, Chen, Songyan, Li, Cheng, Wang, Jianyuan, Huang, Wei
• Format: Article
• Language: English
• Subjects: amorphous Ge interlayer; bubble-free interface; carrier transport; electrical characteristics
• ISSN: 1674-4926
• DOI: 10.1088/1674-4926/39/11/113001

An amorphous Ge (a-Ge) intermediate layer is introduced into the Si bonded interface to lower the annealing temperature and achieve good electrical characteristics. The interface and electrical characteristics of n-Si/n-Si and p-Si/n-Si junctions manufactured by low-temperature wafer bonding based on a thin amorphous Ge are investigated. It is found that the bubble density tremendously decreases when the a-Ge film is not immersed in DI water. This is due to the decrease of the −OH groups. In addition, when the samples are annealed at 400 °C for 20 h, the bubbles totally disappear. This can be explained by the appearance of the polycrystalline Ge (absorption of H2) at the bonded interface. The junction resistance of the n-Si/n-Si bonded wafers decreases with the increase of the annealing temperature. This is consistent with the recrystallization of the a-Ge when high-temperature annealing is conducted. The carrier transport of the Si-based PN junction annealed at 350 °C is consistent with the trap-assisted tunneling model and that annealed at 400 °C is related to the carrier recombination model.