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Proceedings Paper

Sapphire direct bonding as a platform for pressure sensing at extreme high temperatures
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Paper Abstract

Direct bonding between two epitaxy-ready (EPI polished) sapphire wafers is demonstrated as the basis for an all-sapphire pressure sensor. Through chemical processing, hydrogen pre-bonding, and a final high-temperature bakeout, the two single-crystal wafers are directly bonded without the use of any adhesive or intermediate layer. Dicing across the edge of the structure and inspection of the diced pieces with a scanning electron microscope (SEM) indicates a successful direct bond. Control of the bonding wave generates an air bubble sealed between the two bonded sapphire wafers. Optical interference-based measurements of the bubble height and shape at pressures from 0 to 60psig prove that the bubble is sealed by the bonded wafers and demonstrate the potential for sapphire direct bonding as a means of constructing an all-sapphire pressure sensor. Since the structure contains no adhesives, such an all-sapphire sensor is ideal for pressure sensing in extremely harsh, high-temperature environments, potentially operating at temperatures over 1500°C.

Paper Details

Date Published: 27 April 2009
PDF: 10 pages
Proc. SPIE 7316, Fiber Optic Sensors and Applications VI, 73160Y (27 April 2009); doi: 10.1117/12.820079
Show Author Affiliations
Evan M. Lally, Virginia Polytechnic Institute and State Univ. (United States)
Yong Xu, Virginia Polytechnic Institute and State Univ. (United States)
Anbo Wang, Virginia Polytechnic Institute and State Univ. (United States)

Published in SPIE Proceedings Vol. 7316:
Fiber Optic Sensors and Applications VI
Eric Udd; Henry H. Du; Anbo Wang, Editor(s)

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