Room-temperature Si-Si and Si-SiN wafer bonding

Nano-adhesion layer bonding method is proposed for heterogeneous wafer bonding at room temperature. In this method, the wafer surfaces are sputtered by Ar-ion and deposited with Fe nano-adhesion layers simultaneously. Si-Si and Si-SiN wafers are thus directly bonded at room temperature. The bonding strength is increased by optimizing Fe composition ratio on the Si surfaces. The microstructure and chemical states of the bonding interface are characterized using cross-sectional HRTEM, STEM and EELS. Moreover, our results demostrate that the nano-adhesion layer is formed across the bonding interfaces, which are composed of Si/FeSi/Si and Si/FeSi/FeSiN/SiN for Si-Si and Si-SiN bonding interfaces, respectively.