Recycled low-temperature direct bonding of Si/glass and glass/glass chips for detachable micro/nanofluidic devices

Chenxi Wang¹，Hui Fang¹，Shicheng Zhou¹，Xiaoyun Qi¹，Fanfan Niu²，Wei Zhang¹，Yanhong Tian¹，Tadatomo Suga^3,4

1. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology2. School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology3. Collaborative Research Center, Meisei University4. Department of Precision Engineering, School of Engineering, The University of Tokyo

摘 要：Silicon and glass are two of the most ideal materials for micro/nanofluidic devices, which have been widely used for research in multidisciplinary fields. However, many micro/nanofluidic devices enable only single use due to the irreversible bonding between Si/glass or glass/glass chips. If the silicon-and glass-based devices are fabricated to be detachable, the substrates can be reused and bonded again without repeating expensive micro/nanofabrication processes. Herein, we present a recycled direct bonding method for Si/glass and glass/glass chips based on oxygen plasma activation and low-temperature annealing processes. Strong bonding strength and void-free bonding interface are obtained after annealing at 150℃. The surfaces and the bonding interfaces are characterized to elucidate the bonding mechanisms.Moreover, immersion tests are carried out to investigate the interfacial corrosion resistance in various chemical and biological solutions as well as explore a detachable method. The bonding strengths are controlled to meet the demand for micro/nanofluidic devices and the bonding interfaces can be separated in ethanol. As a result, we succeed in the experiment of bonding and detaching of glass substrates without fracturing, which is repeated for three times.

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