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28 February 2005 Wafer-level packaging of pressure sensor using SU8 photoresist
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This paper presents a wafer level packaging solution for MEMS devices using wafer to wafer bonding with SU8-5 negative photoresist. A sensitive piezoelectric pressure sensor with the pressure range between 0 and 0.4 bar was chosen to test the quality of the solution. As stress induced by the packaging technique is the main challenge in MEMS encapsulation, the piezoresistive pressure sensors with its tensometric bridge offer a good opportunity for testing the packaging solution. The offset modification of the diffused piezoresistive Wheatstone bridge fabricated on a 15 μm thin diaphragm is directly influenced by the value of the stress induced by the packaging. In our paper the silicon wafer with pressure sensors is sandwiched between a bottom silicon wafer with etched holes for the applied pressure and a top glass wafer with via-holes and metallization leads. Silicon and Pyrex glass (Corning 7740) was used as materials for packaging mainly due to their thermal coefficient of expansion. The results, variation of tensometric bridge in the range between -5 mV to +5 mV at 10 VDC power supply shows that the packaging solution can be applied for MEMS packaging.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ciprian I. Iliescu, Francis Eng Hock Tay, Jianmin Miao, and Marioara Avram "Wafer-level packaging of pressure sensor using SU8 photoresist", Proc. SPIE 5649, Smart Structures, Devices, and Systems II, (28 February 2005);

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