Room-temperature Si-SiN wafer bonding by nano-adhesion layer method

Nano-Adhesion layer bonding method is proposed for heterogeneous wafer bonding at room temperature. The wafer surface is smooth, clean, and activated by nano-adhesion layer method which sputter cleaning and deposition Fe simultaneously. Si-Si and Si-SiN wafers were directly bonded at room temperature and the bonding strength was increased by optimizing Fe composition ratio on the Si surfaces. We analyzed atomic structure and bonding states at bonding interface by using cross-sectional HRTEM, STEM and EELS and discussed nano-adhesion layer formation, bonding interface structure, and bonding mechanisms. Our results show that bonding interfaces are composed of Si/FeSi/Si and Si/FeSi/FeSiN/SiN of Si-Si and Si-SiN, respectively.