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Proceedings Paper

Laser joining of glass to silicon using adhesive for MEMS packaging applications
Author(s): F. Bardin; S. Kloss; C. H. Wang; A. Moore; A. Jourdain; I. De Wolf; D. P. Hand
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Paper Abstract

Laser joining is a promising technique for wafer-level bonding. It avoids subjecting the complete MEMS package to a high temperature and/or the high electric field associated with conventional wafer-level bonding processes, using the laser to provide only localized heating. We demonstrate that a benzo-cyclo-butene (BCB) polymer, used as an intermediate bonding layer in packaging of MEMS devices, can be satisfactorily cured with a substantial reduction of curing time compared with an oven-based process by using laser heating. A glass-on-silicon cavity bonded with a BCB ring can be produced in few seconds at typical laser intensity of 1 W/mm2 resulting in a local temperature of ~ 300°C. Hermeticity and bond strength tests show that such cavities have similar or better performance than cavities sealed by a commercial substrate bonders which require a minimum curing time of 10 minutes. The influence of exposure time, laser power and pressure on degree of cure, bond strength and hermeticity is investigated. The concept of using a large area, uniform laser beam together with a simple mirror mask is tested, demonstrating that such a mask is capable of protecting the centre of the cavity from the laser beam; however to prevent lateral heating via conduction through the silicon a high conductivity heat sink is required to be in good thermal contact with the rear of the silicon.

Paper Details

Date Published: 15 February 2006
PDF: 12 pages
Proc. SPIE 6107, Laser-based Micropackaging, 610702 (15 February 2006); doi: 10.1117/12.644741
Show Author Affiliations
F. Bardin, Heriot-Watt Univ. (United Kingdom)
S. Kloss, Heriot-Watt Univ. (United Kingdom)
C. H. Wang, Heriot-Watt Univ. (United Kingdom)
A. Moore, Heriot-Watt Univ. (United Kingdom)
A. Jourdain, IMEC (Belgium)
I. De Wolf, IMEC (Belgium)
D. P. Hand, Heriot-Watt Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 6107:
Laser-based Micropackaging
Friedrich G. Bachmann; Willem Hoving; Yongfeng Lu; Kunihiko Washio, Editor(s)

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