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Radial variations in bond strength for plasma bonded oxidised silicon wafers
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences.
Manuscript (Other academic)
URN: urn:nbn:se:uu:diva-93230OAI: oai:DiVA.org:uu-93230DiVA: diva2:166645
Available from: 2005-05-17 Created: 2005-05-17 Last updated: 2010-01-13Bibliographically approved
In thesis
1. Wafer Bonding for Spaceflight Applications: Processing and Characterisation
Open this publication in new window or tab >>Wafer Bonding for Spaceflight Applications: Processing and Characterisation
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Bonding techniques intended for assembling space microsystems are studied in this work. One of the largest problems in bonding pre-processed semiconductor wafers are the severe process restrictions imposed by material compatibility issues. Plasma processes have shown to be good for sensitive materials integration why the influence of different plasma parameters on the bondability of wafers is particularly studied. Conventional wet chemical and field-assisted methods are also examined. The resulting bond quality is assessed in terms of mechanical strength, homogeneity, and yield.

The effect of spaceflight environment on the reliability of wafer bonds is also investigated. Both high and low temperature annealed bonds are found to be very robust. Effects observed are that low temperature bonds are reinforced by thermal cycling in vacuum and that high temperature bonds degrade slightly by low dose γ irradiation.

Adhesion quantification is important for all bonding. Development of accurate quantification methods is considered necessary since most methods at hand are limited. This work includes the development of the blister test method. Former test structures are improved to be more practical to work with and to yield low experimental scatter. A physical stress model for the improved structure is suggested with which successful predictions of fracture for different test specimen configurations are made. The blister test method is used throughout this work to assess the strength of wafer bonds. The physics background and modelling of other common test methods are also thoroughly analysed. The methods’ practical capabilities and limitations are commented; origin and mitigation of measurement errors are discussed. It is shown that all methods can be significantly improved by small means.

Weibull statistics is introduced as a tool to characterise wafer bonds. This method is suitable to use in brittle materials design as the inherent variability in strength can be properly accounted for.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2005. vi + 33 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 70
Engineering physics, wafer bonding, oxygen plasma, wet chemical, anodic bonding, gamma irradiation, proton irradiation, temperature cycling, vibration, shock, Weibull, adhesion quantification, double cantilever beam, tensile, chevron, blister, Teknisk fysik
National Category
Other Engineering and Technologies
urn:nbn:se:uu:diva-5853 (URN)91-554-6289-8 (ISBN)
Public defence
2005-06-09, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:30
Available from: 2005-05-17 Created: 2005-05-17Bibliographically approved

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