Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Reactive Sputter Deposition of Functional Thin Films
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]

Thin film technology is of great significance for a variety of products, such as electronics, anti-reflective or hard coatings, sensors, solar cells, etc. This thesis concerns the synthesis of thin functional films, reactive magnetron sputter deposition process as such and the physical and functional characterization of the thin films synthesized. Characteristic for reactive sputtering processes is the hysteresis due to the target poisoning. One particular finding in this work is the elimination of the hysteresis by means of a mixed nitrogen/oxygen processing environment for dual sputtering of Alumina-Zirconia thin films. For a constant moderate flow of nitrogen, the hysteresis could be eliminated without significant incorporation of nitrogen in the films. It is concluded that optimum processing conditions for films of a desired composition can readily be estimated by modeling. The work on reactively sputtered SiO2–TiO2 thin films provides guidelines as to the choice of process parameters in view of the application in mind, by demonstrating that it is possible to tune the refractive index by using single composite Six/TiO2 targets with the right composition and operating in a suitable oxygen flow range. The influence of the target composition on the sputter yield is studied for reactively sputtered titanium oxide films. It is shown that by using sub-stoichiometric targets with the right composition and operating in the proper oxygen flow range, it is possible to increase the sputter rate and still obtain stoichiometric coatings. Wurtzite aluminum nitride (w-AlN) thin films are of great interest for electro-acoustic applications and their properties have in recent years been extensively studied. One way to tailor material properties is to vary the composition by adding other elements. Within this thesis (Al,B)N films of the wurtzite structure and a strong c-axis texture have been grown by reactive sputter deposition. Nanoindentation experiments show that the films have nanoindentation hardness in excess of 30 GPa, which is as hard as commercially available hard coatings such as TiN. Electrical properties of w-(Al,B)N thin films were investigated. W-(Al,B)N thin films are found to have a dielectric strength of ~3×106 V/cm, a relatively high k-value around 12 and conduction mechanisms similar to those of AlN. These results serve as basis for further research and applications of w-(Al,B)N thin films. An AlN thin film bulk acoustic resonator (FBAR) and a solidly mounted resonator (SMR) together with a microfluidic transport system have been fabricated. The fabrication process is IC compatible and uses reactive sputtering to deposit piezoelectric AlN thin films with a non-zero mean inclination of the c-axis, which allows in-liquid operation through the excitation of the shear mode. The results on IC-compatibility, Q-values, operation frequency and resolution illustrate the potential of this technology for highly sensitive low-cost micro-biosensor systems for applications in, e.g. point-of-care testing.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. , p. 52
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 945
Keywords [en]
thin film, reactive sputtering, coating, resonator, sensor, FBAR, SMR, aluminum nitride, (Al, B)N
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
URN: urn:nbn:se:uu:diva-175666ISBN: 978-91-554-8403-3 (print)OAI: oai:DiVA.org:uu-175666DiVA, id: diva2:532900
Public defence
2012-09-21, Polhemssalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (Swedish)
Opponent
Supervisors
Available from: 2012-08-17 Created: 2012-06-11 Last updated: 2013-01-22
List of papers
1. Reactive sputtering of SiO2–TiO2 thin film from composite Six/TiO2 targets
Open this publication in new window or tab >>Reactive sputtering of SiO2–TiO2 thin film from composite Six/TiO2 targets
Show others...
2010 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 85, no 2, p. 317-321Article in journal (Refereed) Published
Abstract [en]

Coatings of SiO2–TiO2 films are frequently used in a number of optical thin film applications. In this work we present results from depositing films with variable Si/Ti ratios prepared by reactive sputtering. The different Si/Ti ratios were obtained by varying the target composition of composite single targets. Compared to co-sputtering this facilitates process control and composition uniformity of the films. Varying the oxygen supply during sputter deposition can result in films ranging from metallic/substoichiometric to stoichiometric oxides. Transmittance spectra of the different films are presented and the optical constants are determined from these spectra. Furthermore, the deposition process, films structure and composition of the films are discussed. The study shows that by choosing the right composition and working in the proper oxygen flow range, it is possible to tune the refractive index.

Keywords
Reactive sputtering; Optical properties; SixTiO2 films; AR coating
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-133323 (URN)10.1016/j.vacuum.2010.07.003 (DOI)000282548700036 ()
Available from: 2010-11-08 Created: 2010-11-08 Last updated: 2017-12-12Bibliographically approved
2. Experiments and modeling of dual reactive magnetron sputtering using two reactive gases
Open this publication in new window or tab >>Experiments and modeling of dual reactive magnetron sputtering using two reactive gases
Show others...
2008 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 26, no 4, p. 565-570Article in journal (Refereed) Published
Abstract [en]

Reactive sputtering from two elemental targets, aluminum and zirconium, with the addition of two reactive gases, oxygen and nitrogen, is studied experimentally as well as theoretically. The complex behavior of this process is observed and explained. It is shown that the addition of oxygen to a constant supply of nitrogen significantly changes the relative content of aluminum with respect to zirconium in the film. Moreover, it is concluded that there is substantially more oxygen than nitrogen in the films even when the oxygen supply is significantly lower than the nitrogen supply. It is further shown that the addition of a certain minimum constant flow of nitrogen reduces, and eventually eliminates, the hysteresis with respect to the oxygen supply. It is concluded that the presented theoretical model for the involved reactions and mass balance during reactive sputtering of two targets in two reactive gases is in qualitative agreement with the experimental results and can be used to find optimum processing conditions for deposition of films of a desired composition.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-109141 (URN)10.1116/1.2913582 (DOI)000257424200002 ()
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
3. Influence of the target composition on reactively sputtered titanium oxide films
Open this publication in new window or tab >>Influence of the target composition on reactively sputtered titanium oxide films
Show others...
2009 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 83, no 10, p. 1295-1298Article in journal (Refereed) Published
Abstract [en]

Titanium dioxide thin films have many interesting properties and are used in various applications. High refractive index of titania makes it attractive for the glass coating industry, where it is used in low-emissivity and antireflective coatings. Magnetron sputtering is the most common deposition technique for large area coatings and a high deposition rate is therefore of obvious interest. It has been shown previously that high rate can be achieved using substoichiometric targets. This work deals with reactive magnetron sputtering of titanium oxide films from TiOx targets with different oxygen contents. The deposition rate and hysteresis behaviour are disclosed. Films were prepared at various oxygen flows and all films were deposited onto glass and silicon substrates with no external heating. The elemental compositions and structures of deposited films were evaluated by means of X-ray photoelectron spectroscopy, elastic recoil detection analysis and X-ray diffraction. All deposited films were X-ray amorphous. No significant effect of the target composition on the optical properties of coatings was observed. However, the residual atmosphere is shown to contribute to the oxidation of growing films.

Keywords
magnetron sputtering, titanium dioxide, high rate deposition, sputtering, tio2, tio2 films, refractive-index, thin-films, dc, ion, deposition, dioxide, time
National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-110289 (URN)10.1016/j.vacuum.2009.03.026 (DOI)000267505100022 ()0042-207X (ISBN)
Note

Sp. Iss. SI 464KZ Times Cited:0 Cited References Count:19

Available from: 2009-11-09 Created: 2009-11-09 Last updated: 2017-12-12Bibliographically approved
4. Synthesis and characterization of (0001)-textured wurtzite Al(1-x)B(x)N thin films
Open this publication in new window or tab >>Synthesis and characterization of (0001)-textured wurtzite Al(1-x)B(x)N thin films
Show others...
2011 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 6, p. 1033-1036Article in journal (Refereed) Published
Abstract [en]

Al(1-x)B(x)N films of the wurtzite structure and a strong c-axis texture have been grown at room temperature by reactive sputter deposition with B concentrations of up to 10 at.%. The crystallographic structure of the films has been studied with XRD and HRTEM/SAED with stoichiometry and chemical bonding determined by XPS. Nanoindentation experiments show that the films have a hardness in excess of 30 GPa, which is retained after annealing for 1 h at 1000 degrees C. An amorphous phase is observed at the interface, the thickness of which increases with the B concentration in the film, while the film crystallinity is seen to improve with film thickness.

Keywords
Aluminum boron nitride, Wurtzite, Single phase, Hardness, c-texture
National Category
Natural Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-165603 (URN)10.1016/j.surfcoat.2011.07.028 (DOI)000297825600001 ()
Available from: 2012-01-16 Created: 2012-01-09 Last updated: 2017-12-08Bibliographically approved
5. Electrical characterization of wurtzite (Al,B)N thin films
Open this publication in new window or tab >>Electrical characterization of wurtzite (Al,B)N thin films
2011 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, no 4, p. 466-470Article in journal (Refereed) Published
Abstract [en]

Wurtzite aluminum nitride (w-AlN) thin films are of great interest for electro-acoustic applications and their material properties have in recent years been extensively studied. One way to tailor material properties is to vary the composition by adding other elements. Boron is an element that can take the place of aluminum in the crystal lattice of w-AlN. In the present study, polycrystalline w-(AI,B)N thin films were grown on p-Si(100) and Al/p-Si(100) substrates by pulsed DC reactive magnetron sputtering from a single Al/B target. MIS and MIM structures were fabricated to investigate the electrical properties of w-(AI,B)N thin films. Important dielectric thin film properties for microelectronics applications are the breakdown field, the permittivity (K) and leakage current through the film. The (AI,B)N thin film is found to have a dielectric strength of similar to 3 x 10(6) V cm(-1) and a kappa close to 12. The measured leakage current through the film is assumed to be mainly due to Frenkel-Poole emission with a trap energy at 0.71 eV below the conduction band edge.

Place, publisher, year, edition, pages
Elsevier, 2011
Keywords
w-AlBN, Reactive sputtering, Permittivity, Breakdown field, Leakage current
National Category
Natural Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-161821 (URN)10.1016/j.vacuum.2011.10.002 (DOI)000298212000021 ()
Available from: 2011-11-18 Created: 2011-11-18 Last updated: 2017-12-08Bibliographically approved
6. Shear mode AlN thin film electro-acoustic resonant sensor operation in viscous media
Open this publication in new window or tab >>Shear mode AlN thin film electro-acoustic resonant sensor operation in viscous media
Show others...
2007 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 123, no 1, p. 466-473Article in journal (Refereed) Published
Abstract [en]

A shear mode thin film bulk acoustic resonator (FBAR) operating in liquid media together with a microfluidic transport system is presented. The resonator has been fabricated utilizing a recently developed reactive sputter-deposition process for AlN thin films with inclined c-axis relative to the surface normal with a mean tilt of around 30°. The resonator has a resonance frequency of around 1.2 GHz and a Q value in water of around 150. Sensor operation in water and glycerol solutions is characterized. Theoretical analysis of the sensor operation under viscous load as well as of the sensitivity and stability in general is presented. The theoretical predictions are compared with experimental measurements. The results demonstrate clearly the potential of FBAR biosensors for the fabrication of highly sensitive low cost biosensors, bioanalytical tools as well as for liquid sensing in general.

Keywords
AlN, Biosensor, FBAR, Quasi-shear polarized acoustic wave, Thickness mode resonator, Tilted films
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-10554 (URN)10.1016/j.snb.2006.09.028 (DOI)000246171200068 ()
Projects
WISENET
Available from: 2007-04-04 Created: 2007-04-04 Last updated: 2017-12-11Bibliographically approved
7. Fabrication and characterization of a shear mode AlN solidly mounted resonator-silicone microfluidic system for in-liquid applications
Open this publication in new window or tab >>Fabrication and characterization of a shear mode AlN solidly mounted resonator-silicone microfluidic system for in-liquid applications
Show others...
2010 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 159, no 1, p. 111-116Article in journal (Refereed) Published
Abstract [en]

A shear mode AlN solidly mounted resonator (SMR) microfluidic sensor system was fabricated and characterized. The AlN SMR fabrication process is fully IC compatible and uses reactive sputtering to deposit piezoelectric AlN thin films with a non-zero mean inclination of the c-axis, which allows in-liquid operation through the excitation of the shear mode. Silicone encapsulation bonded on top of the Si sensor chip includes a microfluidic system to transport the analyte and confine the flow to the active area of the sensor chip. The sensor operation in air, water, glycerol and acetone was characterized. The resonator had a resonance frequency of around 1.2 GHz and a Q value in water of around 100. Results concerning the stability and resolution are also presented. The results indicate a potential of highly sensitive low-cost microfluidic sensor systems for applications in, e.g. point-of-care testing.

Keywords
surface mounted resonator, pdms, microfluidic system
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-100394 (URN)10.1016/j.sna.2010.02.009 (DOI)000277661800016 ()
Projects
WISENET
Available from: 2009-03-31 Created: 2009-03-31 Last updated: 2017-12-13Bibliographically approved

Open Access in DiVA

Fulltext(2728 kB)2359 downloads
File information
File name FULLTEXT01.pdfFile size 2728 kBChecksum SHA-512
eb4ee62e5e5b8d5166133f8a173d9c99fa0468cf0699aab403394f49408e8c0075f9250da120e52c742f50618e0fb6d74740c45833566ecb0786d11fd9536ee4
Type fulltextMimetype application/pdf
Buy this publication >>

Search in DiVA

By author/editor
Liljeholm, Lina
By organisation
Solid State Electronics
Other Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 2359 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1593 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf