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Small footprint wafer-level vacuum packaging using compressible gold sealing rings
KTH, School of Electrical Engineering (EES), Microsystem Technology.
KTH, School of Electrical Engineering (EES), Microsystem Technology.ORCID iD: 0000-0001-9552-4234
KTH, School of Electrical Engineering (EES), Microsystem Technology.ORCID iD: 0000-0002-0525-8647
2011 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 21, no 8, 085011- p.Article in journal (Refereed) Published
Abstract [en]

A novel low-temperature wafer-level vacuum packaging process is presented. The process uses plastically deformed gold rings as sealing structures in combination with flux-free soldering to provide the bond force for a sealing wafer. This process enables the separation of the sealing and the bonding functions both spatially on the wafer and temporally in different process steps, which results in reduced areas for the sealing rings and prevents outgassing from the solder process in the cavity. This enables space savings and yields improvements. We show the experimental result of the hermetic sealing. The leak rate into the packages is determined, by measuring the package lid deformation over 10 months, to be lower than 3.5 x 10(-13) mbar l s(-1), which is suitable for most MEMS packages. The pressure inside the produced packages is measured to be lower than 10 mbar.

Place, publisher, year, edition, pages
2011. Vol. 21, no 8, 085011- p.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-37545DOI: 10.1088/0960-1317/21/8/085011ISI: 000293163700011ScopusID: 2-s2.0-80051509093OAI: diva2:434700
QC 20110816Available from: 2011-08-16 Created: 2011-08-15 Last updated: 2013-03-25Bibliographically approved
In thesis
1. Wafer-scale Vacuum and Liquid Packaging Concepts for an Optical Thin-film Gas Sensor
Open this publication in new window or tab >>Wafer-scale Vacuum and Liquid Packaging Concepts for an Optical Thin-film Gas Sensor
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis treats the development of packaging and integration methods for the cost-efficient encapsulation and packaging of microelectromechanical (MEMS) devices. The packaging of MEMS devices is often more costly than the device itself, partly because the packaging can be crucial for the performance of the device. For devices which contain liquids or needs to be enclosed in a vacuum, the packaging can account for up to 80% of the total cost of the device.

The first part of this thesis presents the integration scheme for an optical dye thin film NO2-gas sensor, designed using cost-efficient implementations of wafer-scale methods. This work includes design and fabrication of photonic subcomponents in addition to the main effort of integration and packaging of the dye-film. A specific proof of concept target was for NO2 monitoring in a car tunnel.

The second part of this thesis deals with the wafer-scale packaging methods developed for the sensing device. The developed packaging method, based on low-temperature plastic deformation of gold sealing structures, is further demonstrated as a generic method for other hermetic liquid and vacuum packaging applications. In the developed packaging methods, the mechanically squeezed gold sealing material is both electroplated microstruc- tures and wire bonded stud bumps. The electroplated rings act like a more hermetic version of rubber sealing rings while compressed in conjunction with a cavity forming wafer bonding process. The stud bump sealing processes is on the other hand applied on completed cavities with narrow access ports, to seal either a vacuum or liquid inside the cavities at room temperature. Additionally, the resulting hermeticity of primarily the vacuum sealing methods is thoroughly investigated.

Two of the sealing methods presented require permanent mechanical fixation in order to complete the packaging process. Two solutions to this problem are presented in this thesis. First, a more traditional wafer bonding method using tin-soldering is demonstrated. Second, a novel full-wafer epoxy underfill-process using a microfluidic distribution network is demonstrated using a room temperature process.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. ix, 65 p.
Trita-EE, ISSN 1653-5146 ; 2013:010
Microelectromechanical systems, MEMS, Nanoelectromechanical systems, NEMS, silicon, wafer-level, packaging, vacuum packaging, liquid encapsulation, integration, wire bonding, grating coupler, waveguide, Fabry-Perot resonator
National Category
Engineering and Technology
urn:nbn:se:kth:diva-119839 (URN)978-91-7501-676-4 (ISBN)
Public defence
2013-04-19, Q2, Osquldas Väg 10, KTH, Stockholm, 10:00 (English)

QC 20130325

Available from: 2013-03-25 Created: 2013-03-24 Last updated: 2013-03-25Bibliographically approved

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Antelius, MikaelStemme, GöranNiklaus, Frank
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