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Advanced MEMS Pressure Sensors Operating in Fluids
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Today’s MEMS technology allows manufacturing of miniaturized, low power sensors that sometimes exceeds the performance of conventional sensors. The pressure sensor market today is dominated by MEMS pressure sensors.

In this thesis two different pressure sensor techniques are studied. The first concerns ways to improve the sensitivity in the most commonly occurring pressure sensor, namely such based on the piezoresistive technique. Since the giant piezoresistive effect was observed in silicon nanowires, it was assumed that a similar effect could be expected in nano-thin silicon films. However, it turned out that the conductivity was extremely sensitive to substrate bias and could therefore be controlled by varying the backside potential. Another important parameter was the resistivity time drift. Long time measurements showed a drastic variation in the resistance. Not even after several hours of measurement was steady state reached. The drift is explained by hole injection into the buried oxide as well as existence of mobile charges. The piezoresistive effect was studied and shown to be of the same magnitude as in bulk silicon. Later research has shown the existence of such an effect where the film thickness has to be less than around 20 nm. 

The second area that has been studied is the pressure sensitivity of in acoustic resonators. Aluminium nitride thin film plate acoustic resonators (FPAR) operating at the lowest-order symmetric (S0), the first-order asymmetric (A1) as well as the first-order symmetric (S1) Lamb modes have been theoretically and experimentally studied in a comparative manner. The S0 Lamb mode is identified as the most pressure sensitive FPAR mode. The theoretical predictions were found to be in good agreement with the experiments. Additionally, the Lamb modes have been tested for their sensitivities to mass loading and their ability to operate in liquids, where the S0 mode showed good results.

Finally, the pressure sensitivity in aluminium nitride thin film bulk wave resonators employing c- and tilted c-axis texture has been studied. The c-axis tilted FBAR demonstrates a substantially higher pressure sensitivity compared to its c-axis oriented counterpart. 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. , 54 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 933
Keyword [en]
pressure sensor, piezoresistance, nanofilms, AlN, microacoustic, Lamb wave, thin film, resonator, sensitivity
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
URN: urn:nbn:se:uu:diva-173182ISBN: 978-91-554-8369-2OAI: oai:DiVA.org:uu-173182DiVA: diva2:516992
Public defence
2012-06-05, Polhelmsalen, Ångströmslaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2012-05-15 Created: 2012-04-20 Last updated: 2012-08-01Bibliographically approved
List of papers
1. Resistance Electric Field Dependence and Time Drift of Piezoresistive Single Crystalline Silicon Nanofilms
Open this publication in new window or tab >>Resistance Electric Field Dependence and Time Drift of Piezoresistive Single Crystalline Silicon Nanofilms
2009 (English)In: Proceedings of Eurosensors May 2009, Procedia Chemistry vol 1 (1), 2009, 80-83 p.Conference paper (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-122014 (URN)
Conference
Eurosensors May 2009, Proceedings of Eurosensors May 2009, Procedia Chemistry vol 1 (1)
Projects
WISENETVR-621-2006-5881
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2016-04-14Bibliographically approved
2. Drift in thin film SOI piezoresistors
Open this publication in new window or tab >>Drift in thin film SOI piezoresistors
Show others...
2010 (English)In: Proc. of EUROSOI Workshop, 2010 Jan 25-27, Grenoble, France, 2010, 71-72 p.Conference paper, Presentation (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-136179 (URN)
Conference
EUROSOI 2010 Jan 25-27, Grenoble, France
Available from: 2010-12-10 Created: 2010-12-10 Last updated: 2016-04-18Bibliographically approved
3. Sensitivity Features of Thin Film Plate Acoustic Wave Resonators
Open this publication in new window or tab >>Sensitivity Features of Thin Film Plate Acoustic Wave Resonators
2011 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 11, no 12, 3330-3331 p.Article in journal (Refereed) Published
Abstract [en]

Thin film plate acoustic resonators devices operating in the lowest order symmetric Lamb wave mode (S0) in coriented aluminum nitride (AlN) membranes on Si were fabricated and tested for their sensitivities to pressure and mass as well as for their ability to work in liquid environment.

Place, publisher, year, edition, pages
IEEE Sensors Council, 2011
Keyword
Film bulk acoustic resonators, Resonant frequency, Sensitivity, Sensors, Surface acoustic waves
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-157877 (URN)10.1109/JSEN.2011.2158094 (DOI)000301878500019 ()
Projects
VR "Thin Film Guided Microacoustic Waves in Periodical Systems: Theory and Applications"
Funder
Swedish Research Council, 2009-5056
Available from: 2011-08-24 Created: 2011-08-24 Last updated: 2016-04-19Bibliographically approved
4. Lamb wave resonant pressure micro-sensor utilizing a thin-film aluminium nitride membrane
Open this publication in new window or tab >>Lamb wave resonant pressure micro-sensor utilizing a thin-film aluminium nitride membrane
2011 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 21, no 8, 085010- p.Article in journal (Refereed) Published
Abstract [en]

In this work, pressure sensitivities of aluminium nitride (AlN) thin film plate acoustic resonators (FPAR) operating at the lowest-order symmetric (S0), the first-order asymmetric (A1) as well as the first-order symmetric (S1) Lamb modes are theoretically and experimentally studied in a comparative manner. The finite element method analysis has also been performed to get a further insight into the FPAR pressure sensitivity. The theoretical predictions are found to be in good agreement with the experiment. The S0 Lamb mode is identified as the most pressure-sensitive FPAR mode, while the A1 and S1 modes are found to be much less sensitive. Further, the S0 and the A1 modes exhibit almost equal temperature sensitivities, which can be exploited to eliminate the temperature drift by comparing the resonance frequencies of the latter two modes.

National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-157028 (URN)10.1088/0960-1317/21/8/085010 (DOI)000293163700010 ()
Funder
Swedish Research Council, 2009-5056
Available from: 2011-08-16 Created: 2011-08-15 Last updated: 2016-04-19
5. Thin Film Plate Wave Resonant Sensor for Pressure and Gravimetric Measurements
Open this publication in new window or tab >>Thin Film Plate Wave Resonant Sensor for Pressure and Gravimetric Measurements
2011 (English)In: Procedia Engineering 25, Eurosensors XXV: Proc. Eurosensors XXV, September 4-7, 2011, Athens, Greece, Elsevier, 2011, 571-574 p.Conference paper (Refereed)
Abstract [en]

Thin film plate acoustic resonators (FPAR) devices operating in the lowest order symmetric Lamb wave mode (S0),the first order asymmetric Lamb wave mode (A1) and the first order symmetric Lamb wave mode (S1), propagatingin c-oriented aluminum nitride (AlN) membranes on Si were fabricated and tested for their sensitivities to pressureand mass. Systematic data on frequency shifts versus rigid mass (layer) thickness and ambient pressure variations arepresented for the different Lamb wave resonances. Further the ability to work in liquid environment of the S0, A1 andS1 modes, respectively, has been tested in view of Bio-sensor applications.

Place, publisher, year, edition, pages
Elsevier, 2011
Series
, Procedia Engineering, ISSN 1877-7058 ; 25
Keyword
Micro, prssure, sensor, radio frequency
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-167002 (URN)10.1016/j.proeng.2011.12.142 (DOI)000300512400139 ()
Conference
25th Eurosensors Conference, SEP 04-07, 2011, Athens, GREECE
Projects
VR Granted
Funder
Swedish Research Council, 2009-5056
Available from: 2012-01-18 Created: 2012-01-18 Last updated: 2013-03-13
6. Tilted c-Axis Thin-Film Bulk Wave Resonant Pressure Sensors With Improved Sensitivity
Open this publication in new window or tab >>Tilted c-Axis Thin-Film Bulk Wave Resonant Pressure Sensors With Improved Sensitivity
2012 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 12, no 8, 2653-2654 p.Article in journal (Refereed) Published
Abstract [en]

Aluminum nitride thin film bulk wave resonant pressure sensors employing c- and tilted c-axis texture, have been fabricated and tested for their pressure sensitivities. The c-axis tilted FBAR pressure sensors demonstrate substantially higher pressure sensitivity compared to its c-axis oriented counterpart. More specifically the thickness plate quasi-shear resonance has demonstrated the highest pressure sensitivity while further being able to preserve its performance in liquid environment.

Keyword
AlN, FBAR, pressure sensor, sensitivity, micro-acoustic
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-173179 (URN)10.1109/JSEN.2012.2199482 (DOI)000305584300003 ()
Available from: 2012-04-20 Created: 2012-04-20 Last updated: 2012-09-20Bibliographically approved

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