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Synthesis of c-tilted AlN films with a good tilt and thickness uniformity
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. (Thin Films Group)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. (Thin Films Group)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. (Thin Films Group)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
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2011 (English)In: Proceedings of IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM, New York, USA, 2011, 1238-1241 p.Conference paper, Published paper (Refereed)
Abstract [en]

This communication describes a method for the deposition of thin piezoelectric AlN films with an inclined c-axis relative to the surface normal. Further, the tilt over the wafer is sufficiently uniform and exhibits a planar symmetry as well as good thickness uniformity. Careful control of both the nucleation and growth stages is needed to obtain tilted films with excellent quality. Thus in the nucleation state, it is argued that two independent mechanisms, namely seed layer texture and/or surface roughness, are mainly responsible for the subsequent titled growth. To achieve the latter, however, a certain directionality of the deposition flux is also necessary. The directionality of the deposition flux is achieved through the use of an array of linear magnetrons tilted under a certain angle with respect to the substrate normal.

Place, publisher, year, edition, pages
New York, USA, 2011. 1238-1241 p.
Keyword [en]
AlN, c-axis tilt, piezoelectric, shear waves
National Category
Other Materials Engineering
Identifiers
URN: urn:nbn:se:uu:diva-189952ISI: 000309918400287ISBN: 978-1-4577-1252-4 (print)OAI: oai:DiVA.org:uu-189952DiVA: diva2:582591
Conference
IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS), 18-21 October, 2011, Orlando, FL, USA
Projects
WISENET
Funder
Vinnova
Available from: 2013-01-05 Created: 2013-01-05 Last updated: 2015-01-07
In thesis
1. Synthesis of Thin Piezoelectric AlN Films in View of Sensors and Telecom Applications
Open this publication in new window or tab >>Synthesis of Thin Piezoelectric AlN Films in View of Sensors and Telecom Applications
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The requirements of the consumer market on high frequency devices have been more and more demanding over the last decades. Thus, a continuing enhancement of the devices’ performance is required in order to meet these demands. In a macro view, changing the design of the device can result in an improvement of its performance. In a micro view, the physical properties of the device materials have a strong influence on its final performance. In the case of high frequency devices based on piezoelectric materials, a natural way to improve their performance is through the improvement of the properties of the piezoelectric layer. The piezoelectric material studied in this work is AlN, which is an outstanding material among other piezoelectric materials due to its unique combination of material properties.

This thesis presents results from experimental studies on the synthesis of AlN thin films in view of telecom, microelectronic and sensor applications. The main objective of the thesis is to custom design the functional properties of AlN to best suit these for the specific application in mind. This is achieved through careful control of the crystallographic structure and texture as well as film composition.

The piezoelectric properties of AlN films were enhanced by doping with Sc. Films with different Sc concentrations were fabricated and analyzed, and the coupling coefficient (kt2) was enhanced a factor of two by adding 15% of Sc to the AlN films. The enhancement of kt2 is of interest since it can contribute to a more relaxed design of high frequency devices. Further, in order to obtain better deposition control of c-axis tilted AlN films, a new experimental setup were proposed. When this novel setup was used, films with well-defined thicknesses and tilt uniformity were achieved. Films with such characteristics are very favorable to use in sensors based on electroacoustic devices operating in viscous media. Studies were also performed in order to obtain c-axis oriented AlN films deposited directly on Si substrates at reduced temperatures. The deposition technique used was HiPIMS, and the results indicated significant improvements in the film texture when comparing to the conventional Pulsed DC deposition process.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 83 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1160
Keyword
Aluminum nitride, reactive sputtering, c-axis oriented films, tilted films, electroacoustic devices, piezoelectric materials, Aluminum Scandium Nitride, HiPIMS, high-k dielectric
National Category
Other Materials Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-229588 (URN)978-91-554-8995-3 (ISBN)
Public defence
2014-09-24, Conference Room, FEEC, UNICAMP, Av. Albert Einstein, 400 / Cidade Universitária Zeferino Vaz / Distrito Barão Geraldo, Campinas, Brazil, 14:30 (English)
Opponent
Supervisors
Available from: 2014-09-01 Created: 2014-08-11 Last updated: 2014-09-08

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Moreira, MilenaBjurström, JohanKubart, TomasKuzavas, BjörnKatardjiev, Ilia

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