Abstract
Refilled electrical isolation trenches are created for monolithic integration of high-aspect-ratio MEMS devices and circuitry in the same substrate. The refilled trenches electrically isolate the mechanical elements from each other while maintaining robust mechanical connection. It is found that silicon residue at the terminal of trench and metal stringers along indentation on trench surface are the two main fabrication issues, which often cause short circuit problem for MEMS devices with refilled isolation trenches. In this paper, fabrication challenges and solutions are presented for practical implementation of refilled electrical isolation trenches for high-aspect-ratio SOI MEMS devices. Test structures are designed to inline validate reliability of key steps in the process. Finally, an in-plane capacitive accelerometer is successfully fabricated on 50 μm SOI wafer with the improved fabrication process.
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This work is supported by the “Fundamental Research Funds for the Central Universities” and the “Science Fund for Creative Research Groups of National Natural Science Foundation of China (No.: 51221004)”.
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Xie, J. Fabrication challenges and test structures for high-aspect-ratio SOI MEMS devices with refilled electrical isolation trenches. Microsyst Technol 21, 1719–1727 (2015). https://doi.org/10.1007/s00542-014-2357-7
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DOI: https://doi.org/10.1007/s00542-014-2357-7