Research on a 3D Encapsulation Technique for Capacitive MEMS Sensors Based on Through Silicon Via
Research on a 3D Encapsulation Technique for Capacitive MEMS Sensors Based on Through Silicon Via
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基于硅通孔的电容式MEMS传感器3D封装技术研究
DOI：
10.3390/s19010093
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发表时间：
2019-01-01
期刊：
影响因子：
3.9
通讯作者：
Ning, Jin
中科院分区：
文献类型：
--
作者：
Zhang, Meng;Yang, Jian;Ning, Jin
研究了一种适用于电容式微机电系统（MEMS）传感器的新型三维气密封装技术。采用硅中玻璃（GIS）回流工艺，将具有硅通孔（TSV）的复合衬底用作封装帽。特别地，嵌入在玻璃帽中的低电阻率硅柱被设计为同时用作电馈通和固定电容板，以简化制造工艺并提高可靠性。系统地研究了封装帽的制备工艺和性能。硅垂直馈通的电阻被测量为低至263.5 mΩ，表明良好的电互连特性。此外，玻璃和硅的表面均方根（RMS）粗糙度分别为1.12 nm和0.814 nm，这是足够小的最终晶片键合过程。在真空中进行封装帽和具有感测结构的硅晶片之间的阳极键合以完成密封封装。该封装方案已成功应用于电容式陀螺仪。封装后的陀螺品质因数达到220，000以上，比未封装的陀螺品质因数提高了至少一个数量级。所提出的封装方案的有效性可以被验证。封装失效率小于1%，验证了该技术用于高性能MEMS真空封装的可行性和可靠性。
A novel three-dimensional (3D) hermetic packaging technique suitable for capacitive microelectromechanical systems (MEMS) sensors is studied. The composite substrate with through silicon via (TSV) is used as the encapsulation cap fabricated by a glass-in-silicon (GIS) reflow process. In particular, the low-resistivity silicon pillars embedded in the glass cap are designed to serve as the electrical feedthrough and the fixed capacitance plate at the same time to simplify the fabrication process and improve the reliability. The fabrication process and the properties of the encapsulation cap were studied systematically. The resistance of the silicon vertical feedthrough was measured to be as low as 263.5 mΩ, indicating a good electrical interconnection property. Furthermore, the surface root-mean-square (RMS) roughnesses of glass and silicon were measured to be 1.12 nm and 0.814 nm, respectively, which were small enough for the final wafer bonding process. Anodic bonding between the encapsulation cap and the silicon wafer with sensing structures was conducted in a vacuum to complete the hermetic encapsulation. The proposed packaging scheme was successfully applied to a capacitive gyroscope. The quality factor of the packaged gyroscope achieved above 220,000, which was at least one order of magnitude larger than that of the unpackaged. The validity of the proposed packaging scheme could be verified. Furthermore, the packaging failure was less than 1%, which demonstrated the feasibility and reliability of the technique for high-performance MEMS vacuum packaging.