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  • 1.
    Carter, Sarah-Sophia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Nguyen, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Moreira, Milena
    Uppsala University, Science for Life Laboratory, SciLifeLab.
    Tenje, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Medical grade titanium on-chip: assessing the biological properties of biomaterials for bone regeneration2019Conference paper (Other academic)
    Abstract [en]

    Medical grade titanium on-chip: assessing the biological properties of biomaterials for bone regeneration

     

    Sarah-Sophia D. Carter1, Hugo Nguyen2, Milena Moreira1, Maria Tenje1, and Gemma Mestres1

    1Department of Engineering Sciences, Science for Life Laboratory, Uppsala University, Sweden

    2Department of Engineering Sciences, Uppsala University, Sweden

     

    Introduction

    Before entering the clinic, biomaterials need to be thoroughly evaluated, which requires accurate in vitro models. In this work, we have developed a microfluidic device that could be used to assess the biological properties of biomaterials, in a more in vivo-like environment than what is currently possible.

     

    Methods

    Our device consists of a polydimethylsiloxane (PDMS, Sylgard 184) microfluidic channel (l= 6 mm, w= 2 mm, h= 200 µm) and a titanium disc (Ti6Al4V, at bottom), held together by an additively manufactured fixture (Fig. 1A). PDMS was cured overnight at 65°C on a silicon wafer master. Once the microchannel and titanium disc were positioned, MC3T3-E1 pre-osteoblast-like cells were seeded (50,000 cells/cm2). After 5 hours incubation under standard culture conditions, flow was started (2 μl/min). As a control, MC3T3-E1 cells were seeded onto plain titanium discs off-chip. Cell viability and morphology were assessed after 20 hours by calcein-AM/propidium iodide (PI), staining live and dead cells respectively.

     

    Results and discussion

    Figure 1B and 1C show calcein-AM/PI stained MC3T3-E1 cells cultured on-chip and figure 1D shows the control, MC3T3-E1 cells cultured off-chip. The potential to culture cells in our chip was confirmed by the presence of a majority of viable cells (green) with a similar morphology as the control sample. The reason for the increased amount of dead cells (red) on-chip compared to the control needs to be further examined, which requires longer-term experiments.

    Conclusion

    We have set the first steps towards a microfluidic tool for the assessment of biological properties of biomaterials.

  • 2.
    Fornell, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Söderbäck, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Liu, Zhenhua
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Moreira, Milena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Tenje, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Fabrication of Silicon Microfluidic Chips for Acoustic Particle Focusing Using Direct Laser Writing2020In: Micromachines, ISSN 2072-666X, E-ISSN 2072-666X, Vol. 11, no 2, article id 113Article in journal (Refereed)
    Abstract [en]

    We have developed a fast and simple method for fabricating microfluidic channels in silicon using direct laser writing. The laser microfabrication process was optimised to generate microfluidic channels with vertical walls suitable for acoustic particle focusing by bulk acoustic waves. The width of the acoustic resonance channel was designed to be 380 µm, branching into a trifurcation with 127 µm wide side outlet channels. The optimised settings used to make the microfluidic channels were 50% laser radiation power, 10 kHz pulse frequency and 35 passes. With these settings, six chips could be ablated in 5 h. The microfluidic channels were sealed with a glass wafer using adhesive bonding, diced into individual chips, and a piezoelectric transducer was glued to each chip. With acoustic actuation at 2.03 MHz a half wavelength resonance mode was generated in the microfluidic channel, and polystyrene microparticles (10 µm diameter) were focused along the centre-line of the channel. The presented fabrication process is especially interesting for research purposes as it opens up for rapid prototyping of silicon-glass microfluidic chips for acoustofluidic applications.

  • 3.
    Kubart, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Moreira, Milena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thin AlN films deposited by reactive HiPIMS and pulsed DC sputtering – a comparative study2014In: 14th International Conference on Plasma Surface Engineering, September 15 - 19, 2014, Garmisch-Partenkirchen, Germany, 2014Conference paper (Refereed)
    Abstract [en]

    High quality wurtzite polycrystalline thin AlN films can be grown at low temperature by reactive magnetron sputtering provided sufficient energy input. Typically, a suitable substrate or a seed layer is used to improve the AlN crystallinity. In this study, thin films grown by pulsed DC (PDCS) and High Power Impulse Magnetron Sputtering (HiPIMS) from an Al target were studied aiming at both higher film quality as well as film deposition in cases where a seed layer is impractical. The deposition process was first characterized with respect to the Ar to N2 gas flow ratio. For selected process conditions, AlN films were prepared with a thickness of about 200 nm.  (100) Si and (110) Mo coated Si substrates were used and no intentional substrate heating was employed. The crystalline texture of the AlN films was determined with various XRD techniques.

    Although the deposition rates with HiPIMS are generally lower than those with PDCS, the transition from metal to compound mode spans over a significantly larger range of N2 gas flow. Therefore, with HiPIMS it is possible to deposit stoichiometric AlN in the transition region at deposition rates comparable with PDCS. Owing to the increased energy input in the HiPIMS process, the film texture is improved which is especially pronounced at low film thicknesses.

  • 4.
    Kubart, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Moreira, Milena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Highly textured AlN thin films on Si by reactive High Power Impulse Magnetron Sputtering2015In: 42nd ICMCTF 2015 International Conference on Metallurgical Coatings and Thin Films, 20–24 April, San Diego, USA: C5.  Thin Films for Active Devices, 2015Conference paper (Refereed)
    Abstract [en]

    Piezoelectric AlN films for electroacoustic devices are typically deposited by magnetron sputtering. Sputtering is compatible with standard microelectronic fabrication processes and requires lower deposition temperatures than other techniques. In order to enhance the texture of AlN, metal seed layers, such as molybdenum, are usually used. Low temperature growth of AlN films for devices where the seed layer cannot be used is challenging.

    Here we report on the growth of thin textured (002) AlN layers directly on Si substrates without any metal seed layer. The films were deposited by reactive High Power Impulse Magnetron sputtering (HiPIMS) from an aluminium target in argon/nitrogen atmosphere. Because in HiPIMS very high degree of ionization of the sputtered material is achieved, this technique provides highly ionized flux to the substrate and thus promotes surface diffusion. Moreover, nitrogen dissociation which occurs in the high density HiPIMS plasma increases reactivity of the nitrogen. For comparison, pulsed DC sputtering was also performed under identical conditions.

    We show that for 200 nm thick AlN films grown on (100) Si, the HiPIMS process produces well textured (002) films already at room temperature while the pulsed DC films are very poor. At 400°C, which is the optimal temperature for pulsed DC deposition, the HiPIMS films are superior with the FWHM value of 5.1 and 14.2° for the HiPIMS and pulsed DC, respectively. No appreciable stresses were observed in the films. The HiPIMS deposition process is more robust than standard DC sputtering and provides sufficient energy input even for configurations with relatively large target-to-substrate distance. It is therefore suitable also for co-sputtering of ternary nitrides based on AlN. 

  • 5. Lima, L.
    et al.
    Moreira, Milena
    Cioldin, F.
    Diniz, J. A.
    Doi, I.
    Tantalum Nitride as Promissing Gate Electrode for MOS Technology2010In: ECS Transactions, ISSN 1938-5862, E-ISSN 1938-6737, Vol. 31, no 1, p. 319-325Article in journal (Refereed)
  • 6. Lima, L.
    et al.
    Moreira, Milena
    Diniz, J.
    Doi, I.
    Titanium nitride as promising gate electrode for MOS technology2012In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, no 6, p. 1427-1430Article in journal (Refereed)
  • 7. Moreira, Milena
    IR-reflectance assessment of the tilt angle of AlN-wurtzite films for shear mode resonators2013Conference paper (Refereed)
  • 8.
    Moreira, Milena A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Deposition of highly textured AlN thin films by reactive high power impulse magnetron sputtering2015In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 33, no 2, article id 021518Article in journal (Refereed)
    Abstract [en]

    Aluminum nitride thin films were deposited by reactive high power impulse magnetron sputtering (HiPIMS) and pulsed direct-current on Si (100) and textured Mo substrates, where the same deposition conditions were used for both techniques. The films were characterized by x-ray diffraction and atomic force microscopy. The results show a pronounced improvement in the AlN crystalline texture for all films deposited by HiPIMS on Si. Already at room temperature, the HiPIMS films exhibited a strong preferred (002) orientation and at 400 degrees C, no contributions from other orientations were detected. Despite the low film thickness of only 200 nm, an x-scan full width at half maximum value of 5.1 degrees was achieved on Si. The results are attributed to the high ionization of sputtered material achieved in HiPIMS. On textured Mo, there was no significant difference between the deposition techniques.

  • 9.
    Moreira, Milena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Bjurström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Synthesis and characterization of highly c-textured Al(1-x)ScxN2012In: Materials Research Society, 2012Conference paper (Refereed)
  • 10.
    Moreira, Milena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Bjurström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Synthesis and characterization of wurtzite Al(1-x)ScxN thin films2012In: International Symposium on Ultrasonics, ferroelectrics and frequency control, 2012Conference paper (Refereed)
  • 11.
    Moreira, Milena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Bjurström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Yantchev, Ventsislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Aluminum scandium nitride thin-film bulk acoustic resonators for wide band applications2011In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, no 1, p. 23-26Article in journal (Refereed)
    Abstract [en]

    Piezoelectric c-textured Al(1-x)ScxN thin films, where the Sc relative concentration, x, varies in the range 0-0.15 have been studied in view of radio frequency (RF) electro-acoustic applications. Thin film bulk acoustic wave resonators (FBARs) employing these films were fabricated and characterized as a function of the Sc concentration for the first time. The measured electromechanical coupling is found to increase by as much as 100% in the above concentration range. The results from this work underline the potential of the c-textured Al(1-x)ScxN based FBARs for wide band RF applications.

  • 12.
    Moreira, Milena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Bjurström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Yantchev, Ventsislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Efficient RF voltage transformer with bandpass filter characteristics2013In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 49, no 3, p. 198-199Article in journal (Refereed)
    Abstract [en]

    A microwave bandpassfilter with a large ratio between the output andthe input impedance has been designed and fabricated. Consequently,it functions both as a voltage transformer and a bandpassfilter, or trans-filter for brevity. It represents a two-port micro-acoustic resonatoremploying Lamb waves in a thin piezoelectric AlNfilm grown ontoa Si carrier substrate with a centre frequency of around 887 MHz.The transfilter has a transformer ratio of 10 and a voltage efficiencyof over 80%. The component has a small size ( < 0.5 mm2) and isshown to sustain power levels of 250 mW. It can be used in avariety of cases where both voltage amplification and frequencyfilter-ing are required. Examples include: charge pumps in RFID tags,energy scavenging, remotely triggered switches, wake-up radios inwireless networks, stand-by units in home electronics etc.

  • 13.
    Moreira, Milena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Bjurström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kuzavas, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Synthesis of c-tilted AlN films with a good tilt and thickness uniformity2011In: Proceedings of IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM, New York, USA, 2011, p. 1238-1241Conference 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.

  • 14.
    Moreira, Milena De Albuquerque
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. University of Campinas, Brazil (UNICAMP).
    Synthesis of Thin Piezoelectric AlN Films in View of Sensors and Telecom Applications2014Doctoral 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.

    List of papers
    1. Thin AlN films deposited by reactive HiPIMS and Pulsed DC sputtering: a comparative study
    Open this publication in new window or tab >>Thin AlN films deposited by reactive HiPIMS and Pulsed DC sputtering: a comparative study
    (English)Manuscript (preprint) (Other academic)
    National Category
    Other Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-229587 (URN)
    Available from: 2014-08-11 Created: 2014-08-11 Last updated: 2014-09-08
    2. Efficient RF voltage transformer with bandpass filter characteristics
    Open this publication in new window or tab >>Efficient RF voltage transformer with bandpass filter characteristics
    2013 (English)In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 49, no 3, p. 198-199Article in journal (Refereed) Published
    Abstract [en]

    A microwave bandpassfilter with a large ratio between the output andthe input impedance has been designed and fabricated. Consequently,it functions both as a voltage transformer and a bandpassfilter, or trans-filter for brevity. It represents a two-port micro-acoustic resonatoremploying Lamb waves in a thin piezoelectric AlNfilm grown ontoa Si carrier substrate with a centre frequency of around 887 MHz.The transfilter has a transformer ratio of 10 and a voltage efficiencyof over 80%. The component has a small size ( < 0.5 mm2) and isshown to sustain power levels of 250 mW. It can be used in avariety of cases where both voltage amplification and frequencyfilter-ing are required. Examples include: charge pumps in RFID tags,energy scavenging, remotely triggered switches, wake-up radios inwireless networks, stand-by units in home electronics etc.

    Place, publisher, year, edition, pages
    iet, 2013
    Keywords
    wireless, Lamb wave, trasnformer, RF
    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-185262 (URN)10.1049/el.2012.3982 (DOI)000318542500023 ()
    Projects
    WiSENET and VR granted "Thin Film Guided Microacoustic Waves in Periodical Systems: Theory and Applications "
    Funder
    VinnovaSwedish Research Council, 2009-5056
    Available from: 2012-11-21 Created: 2012-11-21 Last updated: 2017-12-07Bibliographically approved
    3. Preparation and characterization of high-k aluminium nitride (AlN) thin film for sensor and integrated circuits applications
    Open this publication in new window or tab >>Preparation and characterization of high-k aluminium nitride (AlN) thin film for sensor and integrated circuits applications
    Show others...
    2012 (English)In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, no 6, p. 1454-1457Article in journal (Refereed) Published
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:uu:diva-222608 (URN)10.1002/pssc.201100461 (DOI)
    Note

    Special Issue: 13th International Conference on the Formation of Semiconductor Interfaces (ICFSI-13)

    Available from: 2014-04-11 Created: 2014-04-11 Last updated: 2017-12-05Bibliographically approved
    4. Aluminum scandium nitride thin-film bulk acoustic resonators for wide band applications
    Open this publication in new window or tab >>Aluminum scandium nitride thin-film bulk acoustic resonators for wide band applications
    2011 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, no 1, p. 23-26Article in journal (Refereed) Published
    Abstract [en]

    Piezoelectric c-textured Al(1-x)ScxN thin films, where the Sc relative concentration, x, varies in the range 0-0.15 have been studied in view of radio frequency (RF) electro-acoustic applications. Thin film bulk acoustic wave resonators (FBARs) employing these films were fabricated and characterized as a function of the Sc concentration for the first time. The measured electromechanical coupling is found to increase by as much as 100% in the above concentration range. The results from this work underline the potential of the c-textured Al(1-x)ScxN based FBARs for wide band RF applications.

    Keywords
    Thin film devices, Composite thin films, Acoustic microwave devices
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-156876 (URN)10.1016/j.vacuum.2011.03.026 (DOI)000295312300005 ()
    Projects
    WISENET
    Funder
    VINNOVA
    Available from: 2011-08-10 Created: 2011-08-10 Last updated: 2017-12-08Bibliographically approved
    5. Synthesis of c-tilted AlN films with a good tilt and thickness uniformity
    Open this publication in new window or tab >>Synthesis of c-tilted AlN films with a good tilt and thickness uniformity
    Show others...
    2011 (English)In: Proceedings of IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM, New York, USA, 2011, p. 1238-1241Conference 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
    Keywords
    AlN, c-axis tilt, piezoelectric, shear waves
    National Category
    Other Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-189952 (URN)000309918400287 ()978-1-4577-1252-4 (ISBN)
    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
    6. Electrical characterization and morphological properties of AlN films prepared by dc reactive magnetron sputtering
    Open this publication in new window or tab >>Electrical characterization and morphological properties of AlN films prepared by dc reactive magnetron sputtering
    2011 (English)In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 88, no 5, p. 802-806Article in journal, Meeting abstract (Refereed) Published
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:uu:diva-222603 (URN)10.1016/j.mee.2010.06.045 (DOI)
    Conference
    The 2010 International workshop on “Materials for Advanced Metallization” - MAM 2010
    Available from: 2014-04-11 Created: 2014-04-11 Last updated: 2017-12-05Bibliographically approved
  • 15.
    Moreira, Milena De Albuquerque
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Bjurström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Yantchev, Ventsislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Synthesis and characterization of highly c-textured Al(1-x)Sc(x)N thin films in view of telecom applications2012In: More than moore: Novel materials approaches for functionalized silicon based microelectronics, 2012, p. 012014-Conference paper (Refereed)
    Abstract [en]

    Wurtzite AlN is a piezoelectric material with excellent electro-acoustic properties and is used for the fabrication of high frequency thin film micro-acoustic components, most notably filters, duplexers, resonators, etc. Its moderate electromechanical coupling coefficient (k(t)(2)) of 6%-7% is insufficient for applications requiring larger bandwidths. Recent theoretical and experimental studies indicate that AlN alloyed with Sc exhibits a substantially higher piezoelectric constant than pure AlN. This study aims at determining the main electro-acoustic parameters of Al(1-x)Sc-(x) N in view of large bandwidth applications. To this end, highly c-textured Al(1-x)Sc(x) N thin films have been synthesized with relative Sc concentrations of up to 0,15. Subsequently, FBAR resonators were fabricated and characterized as a function of the Sc content. It is seen that k(t)(2) increases linearly with the latter to a value of 12% for a Sc concentration of x=0,15, while the Q value decreases from 739 to about 348 in the same concentration range. Likewise, the TCF varies from -35,9ppm/degrees C to -39,8ppm/degrees C, while the dielectric constant increases from epsilon=10 to a value of 14,1 for x=0,15. Finally, the relative dielectric losses are seen to increase by approximately a factor of two.

  • 16. Moreira, Milena
    et al.
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    Souza, J. F.
    Diniz, J. A.
    Electrical characterization and morphological properties of AlN films prepared by dc reactive magnetron sputtering2011In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 88, no 5, p. 802-806Article in journal (Refereed)
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    Törndahl, Tobias
    Katardjiev, Ilia
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    Doi, I.
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    Preparation and characterization of high-k aluminium nitride (AlN) thin film for sensor and integrated circuits applications2012In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, no 6, p. 1454-1457Article in journal (Refereed)
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