Abstract
A low temperature direct bonding process with encapsulated metal interconnections was proposed. The process can be realized between silicon wafers or silicon and glass wafers. To establish well-insulated electric connection, sputtered aluminum film was patterned between a bottom thermal SiO2 and a top PE-SiO2; the consequential uneven wafer surface was planarized through a chemical mechanical polishing (CMP) step. Benefit from this smooth surface finish, direct bonding is achieved at room temperature, and a general yielding rate of more than 95% is obtained. Test results confirmed the reliability of the bonding. The main advantages of this new technology are its electric connectivity, low thermal stress and hermeticity. This process can be utilized for the packaging of micro electro mechanical system (MEMS) devices or the production of SOI wafers with pre-fabricated electrodes and wires.
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Acknowledgements
The authors would like to thank the staff of Center for Microtechnologies in TU Chemnitz for their professional and dedicated service. Also special thanks to Sven Uhlig for bonding operation, and Ina Schubert for helpful discussion. The support of the colleagues of the Fraunhofer Institute of Reliability and Micro Integration (FhG-IZM) in Chemnitz is also acknowledged.
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Jia, C., Wiemer, M. & Gessner, T. Direct bonding with on-wafer metal interconnections. Microsyst Technol 12, 391–396 (2006). https://doi.org/10.1007/s00542-005-0034-6
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DOI: https://doi.org/10.1007/s00542-005-0034-6