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Room-Temperature Sealing of Microcavities by Cold Metal Welding
KTH, School of Electrical Engineering (EES), Microsystem Technology.
KTH, School of Electrical Engineering (EES), Microsystem Technology.ORCID iD: 0000-0001-9552-4234
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2009 (English)In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 18, no 6, 1318-1325 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, we present a wafer-to-wafer attachment and sealing method for wafer-level manufacturing of micro-cavities using a room-temperature bonding process. The proposed attachment and sealing method is based on plastic deformation and cold welding of overlapping metal rings to create metal-to-metal bonding and sealing. We present the results from experiments using various bonding process parameters and metal sealing ring designs including their impact on the resulting bond quality. The sealing properties against liquids and vapor of different sealing ring structures have been evaluated for glass wafers that are bonded to silicon wafers. In addition, wafer-level vacuum sealing of microcavities was demonstrated when bonding a silicon wafer to another silicon wafer with the proposed room-temperature sealing and bonding technique.

Place, publisher, year, edition, pages
2009. Vol. 18, no 6, 1318-1325 p.
Keyword [en]
Bonding, fabrication, microelectromechanical devices, packaging, wafer, vacuum, solder
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-19009DOI: 10.1109/jmems.2009.2030956ISI: 000272318900017ScopusID: 2-s2.0-71549130435OAI: diva2:337056
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2010-12-17Bibliographically approved
In thesis
1. Integration and Packaging Concepts for Infrared Bolometer Arrays 
Open this publication in new window or tab >>Integration and Packaging Concepts for Infrared Bolometer Arrays 
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]


Infrared (IR) imaging devices based on energy detection has shown a dramatic development in technology along with an impressive price reduction in recent years. However, for a low-end market as in automotive applications, the present cost of IR cameras is still the main obstacle to broadening their usage. Ongoing research has continuously reduced the system cost. Apart from decreasing the cost of infrared optics, there are other key issues to achieve acceptable system costs, including wafer-level vacuum packaging of the detectors, low vacuum level operation, and the use of standard materials in the detector fabrication. This thesis presents concepts for cost reduction of low-end IR cameras.

     The thesis presents a study of detector performance based on the thermal conductance design of the pixel. A circuit analog is introduced to analyze the basic thermal network effect from the surrounding environment on the conductance from the pixel to the environment. A 3D simulation model of the detector array conductance has been created in order to optimize the performance of the arrays while operated in low vacuum. In the model, Fourier's law of heat transfer is applied to determine the thermal conductance of a composite material pixel. The resulting thermal conductance is then used to predict the performance of the detector array in low vacuum.

     The investigations of resist as the intermediate bonding material for 3D array integration are also reported in the thesis. A study has been made of the nano-imprint resists series mr-I 9000 using a standard adhesive wafer bonding scheme for thermosetting adhesives. Experiments have been performed to optimize the thickness control and uniformity of the nano-imprint resist layer. The evaluation, including assessment of the bonding surface uniformity and planarizing ability of topographical surfaces, is used to demonstrate the suitability of this resist as sacrificial material for heterogeneous detector array integration.

     Moreover, the thesis presents research in wafer-level packaging performed by room temperature bonding. Sealing rings, used to create a cavity, are manufactured by electroplating. The cavity sealing is tested by liquid injection and by monitoring the deflection of the lid membrane of the cavities. A value for the membrane deflection is calculated to estimate the pressure inside the cavities.  

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 58 p.
Trita-EE, ISSN 1653-5146 ; 2009:030
Fabrication, Bonding, packaging, microbolometer, Thermal imaging.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:kth:diva-10690 (URN)978-91-7415-337-8 (ISBN)
2009-06-05, Seminar room floor 5, Osquldas väg 10, Stockholm, 10:00 (English)
Available from: 2009-09-08 Created: 2009-06-25 Last updated: 2010-10-07Bibliographically approved

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Decharat, AditStemme, GöranNiklaus, Frank
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