Investigation of Au/Si Eutectic Wafer Bonding for MEMS Accelerometers
AbstractAu/Si eutectic bonding is considered to BE a promising technology for creating 3D structures and hermetic packaging in micro-electro-mechanical system (MEMS) devices. However, it suffers from the problems of a non-uniform bonding interface and complex processes for the interconnection of metal wires. This paper presents a novel Au/Si eutectic wafer bonding structure and an implementation method for MEMS accelerometer packaging. The related processing parameters influencing the Au/Si eutectic bonding quality were widely investigated. It was found that a high temperature of 400 °C with a low heating/cooling rate of 5 °C/min is crucial for successful Au/Si eutectic bonding. High contact force is beneficial for bonding uniformity, but the bonding strength and bonding yield decrease when the contact force increases from 3000 to 5000 N due to the metal squeezing out of the interface. The application of TiW as an adhesion layer on a glass substrate, compared with a commonly used Cr or Ti layer, significantly improves the bonding quality. The bonding strength is higher than 50 MPa, and the bonding yield is above 90% for the presented Au/Si eutectic bonding. Furthermore, the wafer-level vacuum packaging of the MEMS accelerometer was achieved based on Au/Si eutectic bonding and anodic bonding with one process. Testing results show a nonlinearity of 0.91% and a sensitivity of 1.06 V/g for the MEMS accelerometer. This Au/Si eutectic bonding process can be applied to the development of reliable, low-temperature, low-cost fabrication and hermetic packaging for MEMS devices. View Full-Text
Share & Cite This Article
Li, D.; Shang, Z.; She, Y.; Wen, Z. Investigation of Au/Si Eutectic Wafer Bonding for MEMS Accelerometers. Micromachines 2017, 8, 158.
Li D, Shang Z, She Y, Wen Z. Investigation of Au/Si Eutectic Wafer Bonding for MEMS Accelerometers. Micromachines. 2017; 8(5):158.Chicago/Turabian Style
Li, Dongling; Shang, Zhengguo; She, Yin; Wen, Zhiyu. 2017. "Investigation of Au/Si Eutectic Wafer Bonding for MEMS Accelerometers." Micromachines 8, no. 5: 158.
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.