Abstract
Benzocyclobutene (BCB) is a thermosetting polymer that can form microfluidics and bond top and bottom layers of the microfluidics at the same time, and yields high repeatability and high bonding strength. This paper reports using photosensitive BCB to fabricate microfluidics and to bond with a thermal press for 4 in. wafers. By optimizing the parameters for pattern development and using a three-stage temperature and pressure increment BCB bonding, we realize the whole wafer glass–Si or glass–glass bonding in thermal press without any crack. The wafer-level bonding shows a bonding percentage above 70%, a tensile stress above 4.94 MPa, and a bonding repeatability over 95%. Furthermore, the bonding is compatible with thick electrode integration, that microfluidics with 380 nm thick electrodes underneath can be well-bonded. Our bonding method much reduces the cost compared with bonding BCB in a wafer bonding machine.
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Acknowledgments
This work is financially supported by the A*STAR project IMRE/06-1R0320. We acknowledge Sharon Oh for taking some of the pictures and giving beneficial discussions, and colleagues in SERC nanofabrication and characterisation facility (SNFC) in the Institute of Materials Research and Engineering (IMRE) for providing the fabrication convenience.
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Zhou, X., Virasawmy, S. & Quan, C. Wafer-level BCB bonding using a thermal press for microfluidics. Microsyst Technol 15, 573–580 (2009). https://doi.org/10.1007/s00542-008-0712-2
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DOI: https://doi.org/10.1007/s00542-008-0712-2