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Sensors 2017, 17(9), 2080;

Interface Characteristics of Sapphire Direct Bonding for High-Temperature Applications

Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan 030051, China
Key Laboratory of Instrumentation Science & Dynamic Measurement, Ministry of Education, North University of China,Taiyuan 030051, China
North Automatic Control Technology Institute, Taiyuan 030006, China
Authors to whom correspondence should be addressed.
Received: 14 August 2017 / Revised: 7 September 2017 / Accepted: 8 September 2017 / Published: 11 September 2017
(This article belongs to the Section Physical Sensors)
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In this letter, we present a sapphire direct bonding method using plasma surface activation, hydrophilic pre-bonding, and high temperature annealing. Through the combination of sapphire inductively coupled plasma etching and the direct bonding process, a vacuum-sealed cavity employable for high temperature applications is achieved. Cross-sectional scanning electron microscopy (SEM) research of the bonding interface indicates that the two sapphire pieces are well bonded and the cavity structure stays intact. Moreover, the tensile testing shows that the bonding strength of the bonding interface is in excess of 7.2 MPa. The advantage of sapphire direct bonding is that it is free from the various problems caused by the mismatch in the coefficients of thermal expansion between different materials. Therefore, the bonded vacuum-sealed cavity can be potentially further developed into an all-sapphire pressure sensor for high temperature applications. View Full-Text
Keywords: sapphire; direct bonding; vacuum-sealed cavity; pressure sensor; high temperature sapphire; direct bonding; vacuum-sealed cavity; pressure sensor; high temperature

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Li, W.; Liang, T.; Chen, Y.; Jia, P.; Xiong, J.; Hong, Y.; Lei, C.; Yao, Z.; Qi, L.; Liu, W. Interface Characteristics of Sapphire Direct Bonding for High-Temperature Applications. Sensors 2017, 17, 2080.

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