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  • 1.
    Brenning, Nils
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Univ Paris Saclay, Univ Paris Sud, CNRS, UMR 8578,LPGP, F-91405 Orsay, France.;Linköping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linköping, Sweden..
    Butler, Alexandre
    Univ Paris Saclay, Univ Paris Sud, CNRS, UMR 8578,LPGP, F-91405 Orsay, France..
    Hajihoseini, Hamidreza
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Rudolph, Martin
    Leibniz Inst Surface Engn IOM, Permoserstr 15, D-04318 Leipzig, Germany..
    Raadu, Michael A.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Minea, Tiberiu
    Univ Paris Saclay, Univ Paris Sud, CNRS, UMR 8578,LPGP, F-91405 Orsay, France..
    Lundin, Daniel
    Univ Paris Saclay, Univ Paris Sud, CNRS, UMR 8578,LPGP, F-91405 Orsay, France.;Linköping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linköping, Sweden..
    Optimization of HiPIMS discharges: The selection of pulse power, pulse length, gas pressure, and magnetic field strength2020In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 38, no 3, article id 033008Article in journal (Refereed)
    Abstract [en]

    In high power impulse magnetron sputtering (HiPIMS) operation, there are basically two goals: a high ionized flux fraction of the sputtered target material and a high deposition rate. In this work, it is demonstrated that the former always comes at the cost of the latter. This makes a choice necessary, referred to as the HiPIMS compromise. It is here proposed that this compromise is most easily made by varying the discharge current amplitude, which opens up for optimization of additionally four external process parameters: the pulse length, the working gas pressure, the magnetic field strength, and the degree of magnetic unbalance to achieve the optimum combination of the ionized flux fraction and the deposition rate. As a figure of merit, useful for comparing different discharges, ( 1 - beta t ) is identified, which is the fraction of ionized sputtered material that escapes back-attraction toward the cathode target. It is shown that a discharge with a higher value of ( 1 - beta t ) always can be arranged to give better combinations of ionization and deposition rate than a discharge with a lower ( 1 - beta t ). Maximization of ( 1 - beta t ) is carried out empirically, based on data from two discharges with Ti targets in Ar working gas. These discharges were first modeled in order to convert measured plasma parameters to values of ( 1 - beta t ). The combined effects of varying the different process parameters were then analyzed using a process flow chart model. The effect of varying the degree of unbalance in the studied range was small. For the remaining three parameters, it is found that optimum is achieved by minimizing the magnetic field strength, minimizing the working gas pressure, and minimizing the pulse length as far as compatible with the requirement to ignite and maintain a stable discharge.

  • 2. Cho, H.
    et al.
    Lee, K. P.
    Leerungnawarat, P.
    Chu, S. N. G.
    Ren, F.
    Pearton, S. J.
    Zetterling, Carl-Mikael
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    High density plasma via hole etching in SiC2001In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 19, no 4, p. 1878-1881Article in journal (Refereed)
    Abstract [en]

    Throughwafer vias up to 100 mum deep were formed in 4H-SiC substrates by inductively coupled plasma etching with SF6/O-2 at a controlled rate of similar to0.6 mum min(-1) and use of Al masks. Selectivities of > 50 for SiC over Al were achieved. Electrical (capacitance-voltage: current-voltage) and chemical (Auger electron spectroscopy) analysis techniques showed that the etching produced only minor changes in reverse breakdown voltage, Schottky barrier height, and near surface stoichiometry of the SiC and had high selectivity over common frontside metallization. The SiC etch rate was a strong function of the incident ion energy during plasma exposure. This process is attractive for power SiC transistors intended for high current, high temperature applications and also for SiC micromachining.

  • 3. Gudmundsson, J. T.
    et al.
    Brenning, Nils
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Lundin, D.
    Helmersson, U.
    High power impulse magnetron sputtering discharge2012In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 30, no 3, p. 030801-Article, review/survey (Refereed)
    Abstract [en]

    The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.

  • 4.
    Hajihoseini, H.
    et al.
    Univ Twente, MESA Inst Nanotechnol, Ind Focus Grp XUV Opt, Drienerlolaan 5, NL-7522 NB Enschede, Netherlands..
    Brenning, Nils
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Rudolph, M.
    Leibniz Inst Surface Engn IOM, Permoserstr 15, D-04318 Leipzig, Germany..
    Raadu, Michael A.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Lundin, D.
    Linköping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linköping, Sweden..
    Fischer, J.
    Linköping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linköping, Sweden..
    Minea, T. M.
    Univ Paris Saclay, Univ Paris Sud, Lab Phys Gaz & Plasmas LPGP, UMR 8578 CNRS, F-91405 Orsay, France..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Target ion and neutral spread in high power impulse magnetron sputtering2023In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 41, no 1, article id 013002Article in journal (Refereed)
    Abstract [en]

    In magnetron sputtering, only a fraction of the sputtered target material leaving the ionization region is directed toward the substrate. This fraction may be different for ions and neutrals of the target material as the neutrals and ions can exhibit a different spread as they travel from the target surface toward the substrate. This difference can be significant in high power impulse magnetron sputtering (HiPIMS) where a substantial fraction of the sputtered material is known to be ionized. Geometrical factors or transport parameters that account for the loss of produced film-forming species to the chamber walls are needed for experimental characterization and modeling of the magnetron sputtering discharge. Here, we experimentally determine transport parameters for ions and neutral atoms in a HiPIMS discharge with a titanium target for various magnet configurations. Transport parameters are determined to a typical substrate, with the same diameter (100 mm) as the cathode target, and located at a distance 70 mm from the target surface. As the magnet configuration and/or the discharge current are changed, the transport parameter for neutral atoms xi(tn) remains roughly the same, while transport parameters for ions xi(ti) vary greatly. Furthermore, the relative ion-to-neutral transport factors, xi(ti)/xi(tn), that describe the relative deposited fractions of target material ions and neutrals onto the substrate, are determined to be in the range from 0.4 to 1.1.

  • 5.
    Hajihoseini, Hamidreza
    et al.
    Univ Iceland, Sci Inst, IS-107 Reykjavik, Iceland.;Univ Paris Saclay, Univ Paris Sud, CNRS, UMR 8578,LPGP, F-91405 Orsay, France..
    Cada, Martin
    Acad Sci Czech Republ, Inst Phys, Vvi, Na Slovance 2, Prague 18221 8, Czech Republic..
    Hubicka, Zdenek
    Acad Sci Czech Republ, Inst Phys, Vvi, Na Slovance 2, Prague 18221 8, Czech Republic..
    Unaldi, Selen
    Univ Paris Saclay, Univ Paris Sud, CNRS, UMR 8578,LPGP, F-91405 Orsay, France..
    Raadu, Michael A.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Brenning, Nils
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Linköping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linköping, Sweden..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Univ Iceland, Sci Inst, IS-107 Reykjavik, Iceland..
    Lundin, Daniel
    Univ Paris Saclay, Univ Paris Sud, CNRS, UMR 8578,LPGP, F-91405 Orsay, France.;Linköping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linköping, Sweden..
    Sideways deposition rate and ionized flux fraction in dc and high power impulse magnetron sputtering2020In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 38, no 3, article id 033009Article in journal (Refereed)
    Abstract [en]

    The sideways (radial) deposition rate and ionized flux fraction in a high power impulse magnetron sputtering (HiPIMS) discharge are studied and compared to a dc magnetron sputtering (dcMS) discharge, while the magnetic field strength | B | and degree of balancing are varied. A significant deposition of the film forming material perpendicular to the target surface is observed for both sputter techniques. This sideways deposition decreases with increasing axial distance from the target surface. The sideways deposition rate is always the highest in dc operation, while it is lower for HiPIMS operation. The magnetic field strength has a strong influence on the sideways deposition rate in HiPIMS but not in dcMS. Furthermore, in HiPIMS operation, the radial ion deposition rate is always at least as large as the axial ion deposition rate and often around two times higher. Thus, there are a significantly higher number of ions traveling radially in the HiPIMS discharge. A comparison of the total radial as well as axial fluxes across the entire investigated plasma volume between the target and the substrate position allows for revised estimates of radial over axial flux fractions for different magnetic field configurations. It is here found that the relative radial flux of the film forming material is greater in dcMS compared to HiPIMS for almost all cases investigated. It is therefore concluded that the commonly reported reduction of the (axial) deposition rate in HiPIMS compared to dcMS does not seem to be linked with an increase in sideways material transport in HiPIMS.

  • 6. Hedlund, E.
    et al.
    Malyshev, O. B.
    Westerberg, L.
    Krasnov, A.
    Semenov, A. S.
    Leandersson, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Zajec, B.
    Kollmus, H.
    Bellachioma, M. C.
    Bender, M.
    Kraemer, A.
    Reich-Sprenger, H.
    Heavy-ion induced desorption of a TiZrV coated vacuum chamber bombarded with 5 MeV/u Ar8+ beam at grazing incidence2009In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 27, no 1, p. 139-144Article in journal (Refereed)
    Abstract [en]

    TiZrV nonevaporable getter (NEG) coated vacuum chambers is a new vacuum technology which is already used in many particle accelerators worldwide. This coating is also of interest for heavy-ion accelerator vacuum chambers. Heavy-ion desorption yields from an activated as well as a CO saturated NEG coated tube have been measured with 5 MeV/u Ar8+ beam. The sticking probability of the NEG film was obtained by using the partial pressure ratios on two sides of the NEG coated tube. These ratios were compared to results of modeling of the experimental setup with test particle Monte Carlo and angular coefficient methods. The partial pressures inside the saturated NEG coated tube bombarded with heavy ions were up to 20 times larger than those inside the activated one. However, the partial pressure of methane remained the same. The value of the total desorption yield from the activated NEG coated tube is 2600 molecules/ion. The desorption yields after saturation for CH4, H-2, and CO2 were found to be very close to the yields measured after the activation, while CO increased by up to a factor of 5. The total desorption yield for the saturated tube is up to 7000 molecules/ion. The large value of the desorption yield of the activated NEG coated tube, an order of magnitude higher than the desorption yield from a stainless steel tube at normal incident angle, could be explained by the grazing incident angle.

  • 7.
    Kateb, Movaffaq
    et al.
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland.;Reykjavik Univ, Sch Sci & Engn, IS-102 Reykjavik, Iceland..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Ingvarsson, Snorri
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Effect of substrate bias on microstructure of epitaxial film grown by HiPIMS: An atomistic simulation2020In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 38, no 4, article id 043006Article in journal (Refereed)
    Abstract [en]

    The authors explore the combination of high power impulse magnetron sputtering (HiPIMS) and substrate bias for the epitaxial growth of the Cu film on the Cu (111) substrate by molecular dynamics simulation. A fully ionized deposition flux was used to represent the high ionization fraction in the HiPIMS process. To mimic different substrate bias, the authors assumed the deposition flux with a flat energy distribution in the low, moderate, and high energy ranges. The authors also compared the results of the fully ionized flux with results assuming a completely neutral flux, in analogy with thermal evaporation. It is confirmed that in the low energy regime, HiPIMS presents a slightly smoother surface and more interface mixing compared to that of thermal evaporation. In the moderate energy HiPIMS, however, an atomically smooth surface was obtained with a slight increase in the interface mixing compared to low energy HiPIMS. In the high energy regime, HiPIMS presents severe interface mixing with a smooth surface but limited growth due to resputtering from the surface. The results also indicate that fewer crystal defects appear in the film for moderate energy HiPIMS. The authors attribute this behavior to the repetition frequency of collision events. In particular, the high energy HiPIMS suffers from high repetition of collision events that does not allow the reconstruction of the film. While in the low energy HiPIMS, there are not enough events to overcome the island growth. At moderate energy, collision events repeat in a manner that provides enough time for reconstruction, which results in a smooth surface, fewer defects, and limited intermixing.

  • 8.
    Kateb, Movaffaq
    et al.
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Hajihoseini, Hamidreza
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Ingvarsson, Snorri
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Role of ionization fraction on the surface roughness, density, and interface mixing of the films deposited by thermal evaporation, dc magnetron sputtering, and HiPIMS: An atomistic simulation2019In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, no 3, article id 031306Article in journal (Refereed)
    Abstract [en]

    The effect of ionization fraction on the epitaxial growth of Cu film on Cu (111) substrate at room temperature is explored. Three deposition methods, thermal evaporation, dc magnetron sputtering (dcMS), and high power impulse magnetron sputtering (HiPIMS) are compared. Three deposition conditions, i.e., fully neutral, 50% ionized, and 100% ionized flux were considered thermal evaporation, dcMS, and HiPIMS, respectively, for similar to 20 000 adatoms. It is shown that higher ionization fraction of the deposition flux leads to smoother surfaces by two major mechanisms, i.e., decreasing clustering in the vapor phase and bicollision of high energy ions at the film surface. The bicollision event consists of local amorphization which fills the gaps between islands followed by crystallization due to secondary collisions. The bicollision events are found to be very important to prevent island growth to become dominant and increase the surface roughness. Regardless of the deposition method, epitaxial Cu thin films suffer from stacking fault areas (twin boundaries) in agreement with recent experimental results. Thermal evaporation and dcMS deposition present negligible interface mixing while HiPIMS deposition presents considerable interface mixing. Published by the AVS.

  • 9. Kim, Y. M.
    et al.
    Philipps, V.
    Rubel, Marek J.
    KTH, Superseded Departments (pre-2005), Alfvén Laboratory.
    Retention of neon in graphite after ion beam implantation or exposures to the scrape-off layer plasma in the TEXTOR tokamak2002In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 20, no 1, p. 138-145Article in journal (Refereed)
    Abstract [en]

    The interaction of neon ions with graphite was investigated for targets either irradiated with ion beams (2-10 keV range) or exposed to the scrape-off layer plasma in the TEXTOR tokamak during discharges with neon edge cooling. The emphasis was on the influence of the target temperature (300-1200 K) and the implantation dose on the neon retention and reemission. The influence of deuterium impact on the retention of neon implanted into graphite has also been addressed. In ion beam experiments saturation is observed above a certain ion dose with a saturation level, which decreases with increasing target temperature. The temperature dependence of the thermal desorption cot-responds to an apparent binding energy of about 2.06 eV. The retention of neon (C-Ne/C-C) decreases with increasing ion energy with values from 0.55 to 0.15 following irradiation with 2 and 10 keV ions, respectively. The reemission yield during the irradiation increases with target temperature and above 1200 K all impinging ions are reemitted instantaneously. The retention densities measured using the sniffer probe at the TEXTOR tokamak are less than 1% of the total neon fluence and are over one order of magnitude smaller than those observed in ion beam experiments. The results are discussed in terms of different process decisive for ion deposition and release under the two experimental conditions.

  • 10. Kollmus, H.
    et al.
    Kraemer, A.
    Bender, M.
    Bellachioma, M. C.
    Reich-Sprenger, H.
    Mahner, E.
    Hedlun, E.
    Westerberg, L.
    Malyshev, O. B.
    Leandersson, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Edqvist, E.
    Energy scaling of the ion-induced desorption yield for perpendicular collisions of Ar and U with stainless steel in the energy range of 5 and 100 MeV/u2009In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 27, no 2, p. 245-247Article in journal (Refereed)
    Abstract [en]

    For the GSI future project Facility for Antiproton and Ion Research a beam intensity of 10(12)U(28+)ions/s is planned to be extracted from the GSI heavy ion synchrotron SIS18. Measurements performed in 2001 showed that the beam lifetime of the ions in the synchrotron is decreasing with increasing number of injected particles due to vacuum instabilities caused by ion-induced desorption. The injection energy for the SIS18 is about 10 MeV/u and U28+ ions are accelerated to 200 MeV/u limited by the magnetic rigidity for the low charge state. The aim of this work was to measure the desorption yield as a function of the impact energy from injection to extraction of SIS18 at GSI. Low energy yields at 5.0, 9.7, and 17.7 MeV/u were measured at the Cyclotron of The Svedberg Laboratory in Uppsala. High energy yields at 40, 80, and 100 MeV/u were measured at SIS18 of GSI in a different setup. It was found that the desorption yield scales with the electronic energy loss (dE/dx)(el)(n), with n between 2 and 3, decreasing for increasing impact energy above the Bragg maximum.

  • 11. LARSSON, CUS
    et al.
    FLODSTROM, AS
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    YANG, Y
    CORE-LEVEL SHIFTS ON THE H2O EXPOSED GE(100)2X1 SURFACE1989In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 7, no 3, p. 2044-2048Article in journal (Refereed)
  • 12.
    Magnus, Fridrik
    et al.
    Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Tryggvason, Tryggvi K
    Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Olafsson, Sveinn
    Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Gudmundsson, Jon Tomas
    Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Current-voltage-time characteristics of the reactive Ar/O2 high power impulse magnetron sputtering discharge2012In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 30, no 5, article id 050601Article in journal (Refereed)
    Abstract [en]

    The discharge current–voltage–time waveforms are studied in the reactive Ar/O2 high power impulse magnetron sputtering discharge with a titanium target for 400 μs long pulses. The discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage and the current increases with decreasing frequency or voltage. The authors attribute this to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as an oxide forms on the target.

  • 13. Miniotas, A
    et al.
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Brazdeikis, A
    Chu, C W
    Large magnetoresistance effect in as-grown epitaxial LaxCa1-xMnO3 films prepared by a molecular beam epitaxy coevaporation technique1998In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 16, no 3, p. 1268-1271Article in journal (Refereed)
    Abstract [en]

    Thin films of LaxCa1-xMnO3 (0.64 less than or equal to x less than or equal to 0.68) have been grown by NO2-assisted molecular beam epitaxy on single crystal SrTiO3(100) and LaAlO3(100) substrates. As-grown films are found to be grown epitaxially, b-axis oriented on both SrTiO3 and LaAlO3 substrates, and exhibit a large magnetoresistance effect {[R(O)-R(H)]/R(H)X100} of about 1500% at 214 K. The magnetoresistance effect values obtained are similar to those reported for as-grown LaxCa1-xMnO3 (0.60 less than or equal to x less than or equal to 0.7) films synthesized either by so-called "block-by-block" or "layer-by-layer" molecular beam epitaxy techniques, but the effect appears at significantly higher temperatures. For epitaxial La0.68Ca0.32MnO3 films grown on SrTiO3 a relatively large resistance suppression of 200% at 1.0 T is observed. (C) 1998 American Vacuum Society.

  • 14.
    Renner, M.
    et al.
    Linköping Univ, Dept Phys Chem & Biol IFM, Plasma & Coatings Phys Div, SE-58183 Linköping, Sweden.;Rhein Westfal TH Aachen, DE-52062 Aachen, Germany..
    Fischer, J.
    Linköping Univ, Dept Phys Chem & Biol IFM, Plasma & Coatings Phys Div, SE-58183 Linköping, Sweden.;Evatec AG, Hauptstr 1a, CH-9477 Trubbach, Switzerland..
    Hajihoseini, H.
    Univ Twente, MESA Inst Nanotechnol, Ind Focus Grp XUV Opt, NL-7522 Enschede, Netherlands..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Univ Iceland, Sci Inst, IS-107 Reykjavik, Iceland..
    Rudolph, M.
    Leibniz Inst Surface Engn IOM, DE-04318 Leipzig, Germany..
    Lundin, D.
    Linköping Univ, Dept Phys Chem & Biol IFM, Plasma & Coatings Phys Div, SE-58183 Linköping, Sweden..
    Angular distribution of titanium ions and neutrals in high-power impulse magnetron sputtering discharges2023In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 41, no 3, article id 033009Article in journal (Refereed)
    Abstract [en]

    The angular dependence of the deposition rates due to ions and neutrals in high-power impulse magnetron sputtering (HiPIMS) discharges with a titanium target were determined experimentally using a magnetically shielded and charge-selective quartz crystal microbalance (or ionmeter). These rates have been established as a function of the argon working gas pressure, the peak discharge current density, and the pulse length. For all explored cases, the total deposition rate exhibits a heart-shaped profile and the ionized flux fraction peaks on the discharge axis normal to the cathode target surface. This heart-shaped pattern is found to be amplified at increasing current densities and reduced at increased working gas pressures. Furthermore, it is confirmed that a low working gas pressure is beneficial for achieving high deposition rates and high ionized flux fractions in HiPIMS operation.

  • 15. Rudenja, S.
    et al.
    Pan, Jinshan
    KTH, Superseded Departments (pre-2005), Materials Science and Engineering.
    Odnevall Wallinder, Inger
    KTH, Superseded Departments (pre-2005), Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments (pre-2005), Materials Science and Engineering.
    Kulu, P.
    Mikli, V.
    Enhanced passivity of austenitic AISI 304 stainless steel by low-temperature ion nitriding2001In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 19, no 4, p. 1425-1431Article in journal (Refereed)
    Abstract [en]

    Low-temperature ion nitriding introduces interstitial nitrogen into the austenitic stainless steel matrix. An enhanced passivity of the nitrided stainless steel was detected by anodic potentiodynamic polarization in a 0.1 M H2SO4 + 0.05 M HCl electrolyte. Capacitance measurements by electrochemical impedance spectroscopy revealed a 3-4 nm thick oxide film on the surface of nitrided specimens that is two to three times thicker than on blank specimens. X-ray photoelectron spectroscopy analyses and Auger depth profiles indicate increased chromium uptake into the oxide film on the nitrided surface, supposedly through the kinetically stable oxide-metal interface enriched with nitrogen and nickel. Several possible mechanisms that influence passivation of the nitrided stainless steel may operate simultaneously. Among these mechanisms, austenite strengthening by interstitial nitrogen near the oxide/alloy interface associated with structural defects like dislocation branches and vacancies are most likely the explanation for the enhanced passivity of the nitrided stainless steel.

  • 16.
    Rudolph, M.
    et al.
    Leibniz Inst Surface Engn IOM, Permoserstr 15, D-04318 Leipzig, Germany..
    Brenning, Nils
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Linköping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linköping, Sweden..
    Hajihoseini, H.
    Univ Twente, MESA Inst Nanotechnol, Ind Focus Grp XUV Opt, Drienerlolaan 5, NL-7522 NB Enschede, Netherlands..
    Raadu, Michael A.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Fischer, J.
    Linköping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linköping, Sweden..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Lundin, D.
    Linköping Univ, Plasma & Coatings Phys Div, IFM Mat Phys, SE-58183 Linköping, Sweden..
    Operating modes and target erosion in high power impulse magnetron sputtering2022In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 40, no 4, p. 043005-, article id 043005Article in journal (Refereed)
    Abstract [en]

    Magnetron sputtering combines a glow discharge with sputtering from a target that simultaneously serves as a cathode for the discharge. The electrons of the discharge are confined between overarching magnetic field lines and the negatively biased cathode. As the target erodes during the sputter process, the magnetic field strengthens in the cathode vicinity, which can influence discharge parameters with the risk of impairing reproducibility of the deposition process over time. This is of particular concern for high-power impulse magnetron sputtering (HiPIMS) as the discharge current and voltage waveforms vary strongly with the magnetic field strength. We here discuss ways to limit the detrimental effect of target erosion on the film deposition process by choosing an appropriate mode of operation for the discharge. The goal is to limit variations of two principal flux parameters, the deposition rate and the ionized flux fraction. As an outcome of the discussion, we recommend operating HiPIMS discharges by maintaining the peak discharge current constant.

  • 17.
    Santos, A. C. F.
    et al.
    Univ Fed Rio Janeiro, Inst Fis, BR-21941972 Rio De Janeiro, RJ, Brazil..
    Travnikova, O.
    Sorbonne Univ, CNRS, UMR 7614, Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, Orme Merisiers, BP 48, F-91192 Gif Sur Yvette, Saint-aubin, France..
    Boudjemia, N.
    Sorbonne Univ, CNRS, UMR 7614, Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Univ Oulu, Nano & Mol Syst Res Unit, POB 3000, FI-90014 Oulu, Finland..
    Marchenko, T.
    Sorbonne Univ, CNRS, UMR 7614, Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, Orme Merisiers, BP 48, F-91192 Gif Sur Yvette, Saint-aubin, France..
    Guillemin, R.
    Sorbonne Univ, CNRS, UMR 7614, Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, Orme Merisiers, BP 48, F-91192 Gif Sur Yvette, Saint-aubin, France..
    Ismail, I.
    Sorbonne Univ, CNRS, UMR 7614, Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, Orme Merisiers, BP 48, F-91192 Gif Sur Yvette, Saint-aubin, France..
    Koulentianos, D.
    Sorbonne Univ, CNRS, UMR 7614, Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Univ Gothenburg, Dept Phys, Origovagen 6B, SE-412 96 Gothenburg, Sweden.;Ctr Free Electron Laser Sci, Deutsch Elektronen Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany.;Univ Hamburg, Dept Phys, Luruper Chaussee 149, D-22761 Hamburg, Germany..
    Ceolin, D.
    Synchrotron SOLEIL, Orme Merisiers, BP 48, F-91192 Gif Sur Yvette, Saint-aubin, France..
    Gel'mukhanov, Faris
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Simon, M.
    Sorbonne Univ, CNRS, UMR 7614, Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, Orme Merisiers, BP 48, F-91192 Gif Sur Yvette, Saint-aubin, France..
    Piancastelli, M. N.
    Sorbonne Univ, CNRS, UMR 7614, Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Puettner, R.
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany..
    Resonant Auger decay induced by the symmetry-forbidden 1a(1g)?: 6a(1g) transition of the SF6 molecule2022In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 40, no 4, p. 042801-, article id 042801Article in journal (Refereed)
    Abstract [en]

    Resonant Auger electron spectroscopic study at the symmetry-forbidden 1 a 1 g -> 6 a 1 g excitation below the S K-shell threshold of SF 6 is reported. Partial electron yield and resonant K L L Auger spectra have been measured by using monochromatized undulator synchrotron radiation. By changing the photon energy in small steps, a so-called 2D map is produced. In this map, the dipole-forbidden transition exhibits spectral features (e.g., an S-shaped dispersion relation), which are well known and understood for dipole-allowed transitions. We validate by a theory that for the case of dipole-forbidden transitions, these spectral features can be analyzed in the same way as previously established for the dipole-allowed ones. This approach grants information on the nuclear dynamics in the K-shell core-excited states of SF 6 on the femtosecond (fs) timescale. In particular, for the potential-energy curves of the states S 1 s(-1) 6(a1g) and S 2p(-2)6a(1g), the slopes at the equilibrium distance of the ground state are derived. Symmetry breaking as a result of ultrafast vibronic coupling is revealed by the population of the electronically forbidden excited state. Published under an exclusive license by the AVS.

  • 18. Simpson, W C
    et al.
    Shuh, D K
    Hung, W H
    Hakansson, M C
    Kanski, J
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Yarmoff, J A
    Role of surface stoichiometry in the Cl-2/GaAs(001) reaction1996In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 14, no 3, p. 1815-1821Article in journal (Refereed)
    Abstract [en]

    The room-temperature reaction of Cl-2 with GaAs(001)-4x6, -c(2x8), and -c(4x4) surfaces is studied with synchrotron soft x-ray photoelectron spectroscopy. The chemical composition of the reacted surfaces is found to depend on the stoichiometry of the starting surface. In all cases, the reaction occurs stepwise, with Ga and As monochlorides formed prior to the dichlorides. The Ga-rich surface is initially more reactive than either of the As-rich surfaces and it forms more GaCl than the As-rich surfaces, which instead form more AsCl. The sticking coefficient for chlorine on GaAs(001) decays exponentially with coverage. A contribution from Cl atoms comprising the surface dichlorides is identified in the Cl 2p core-level spectra. (C) 1996 American Vacuum Society.

  • 19.
    Ström, Valter
    et al.
    KTH, Superseded Departments (pre-2005), Physics.
    Rao, K Venkat
    KTH, Superseded Departments (pre-2005), Physics.
    Mapping local susceptibility using a scanning coaxial write/read head1998In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 16, no 4, p. 2687-2692Article in journal (Refereed)
    Abstract [en]

    A technique to study local susceptibility of magnetic material is introduced. We describe a unique probe based on a pair of write/read heads, to measure and model both the susceptibility components at any point on a surface. With this approach it is possible to map the strength and direction of the local in-plane uniaxial susceptibility at surfaces. The usefulness of our technique is validated by measurements on oriented gamma-Fe2O3 in a credit card. In addition, we present studies on an amorphous soft ferromagnet containing different defect structures to reveal the micromagnetic structural details around defects on a surface. Our approach has the distinct advantage of determining the local susceptibility and anisotropy on a length scale not possible by using other techniques available today.

  • 20. Wang, J. J.
    et al.
    Lambers, E. S.
    Pearton, S. J.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zetterling, Carl-Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Grow, J. M.
    Ren, F.
    Shul, R. J.
    Inductively coupled plasma etching of bulk 6H-SiC and thin-film SiCN in NF3 chemistries1998In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 16, no 4, p. 2204-2209Article in journal (Refereed)
    Abstract [en]

    A parametric study of the etching characteristics of 6H p+ and n+ SiC and thin-film SiC0.5N0.5 in inductively coupled plasma (ICP) NF3/O2 and NF3/Ar discharges has been performed. The etch rates in both chemistries increase monotonically with NF3 percentage and rf chuck power. The etch rates go through a maximum with increasing ICP source power, which is explained by a trade-off between the increasing ion flux and the decreasing ion energy. The anisotropy of the etched features is also a function of ion flux, ion energy and atomic fluorine neutral concentration. Indium-tin-oxide masks display relatively good etch selectivity over SiC (maximum of ∌70:1), while photoresist etches more rapidly than SiC. The surface roughness of SiC is essentially independent of plasma composition for NF3/O2 discharges, while extensive surface degradation occurs for SiCN under high NF3:O2 conditions. © 1998 American Vacuum Society.

  • 21. WIGREN, C
    et al.
    ANDERSEN, JN
    NYHOLM, R
    KARLSSON, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    GROWTH AND EPITAXY OF YB SILICIDES ON SI(111)1991In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 9, no 3, p. 1942-1945Article in journal (Refereed)
    Abstract [en]

    Yb silicides have been grown epitaxially on the Si(111) surface using solid-state epitaxy with annealing to 400-degrees-C. The amount of deposited Yb was varied from parts of a monolayer to films being about 40 monolayer thick. Auger- and photoelectron spectroscopy showed that Si segregates into the Yb overlayer at room temperature and that a strong reaction occurs during annealing to 400-degrees-C leading to the formation of thick silicides. The epitaxial silicides showed a 1 x 1 or a unroofed-radical 3 x unroofed-radical 3 low-energy electron diffraction pattern depending on the detailed preparation procedure. The composition of the silicide was found to be YbSi2-x.

  • 22.
    Zarshenas, Mohammad
    et al.
    Fraunhofer Institute for Mechanics of Materials IWM, MicroTribology Center μTC, Woehlerstraße 11, Freiburg 79108, Germany, Woehlerstraße 11; Department of Physics, University of Freiburg, Hermann-Herder-Straße 3, Freiburg 79104, Germany, Hermann-Herder-Straße 3.
    Sangiovanni, Davide G.
    Theoretical Physics Division, Department of Physics, Chemistry, and Biology, Linköping University, Linköping SE-58183, Sweden.
    Sarakinos, Kostas
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering. Department of Physics, University of Helsinki, P.O. Box 43, Helsinki FI-00014, Finland, P.O. Box 43.
    Diffusion and magnetization of metal adatoms on single-layer molybdenum disulfide at elevated temperatures2024In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 42, no 2, article id 023409Article in journal (Refereed)
    Abstract [en]

    The present work models temperature-dependent ( 500 − 1300 K ) diffusion dynamics of Ag, Au, and Cu adatoms on MoS2 as well as electronic and magnetic properties of adatom (Ag, Au, and Cu)/MoS2 systems. Modeling is done by means of ab initio molecular dynamics (AIMD) simulations that account for van der Waals corrections and electronic spin degrees of freedom in the framework of density functional theory. It is found that Ag and Au adatoms exhibit super-diffusive motion on MoS2 at all temperatures, while Cu adatoms follow a random walk pattern of uncorrelated surface jumps. The observed behavior is consistent with AIMD-calculated effective migration barriers E a ( E a Ag = 190 ± 50 meV , E a Au = 67 ± 7 meV , and E a Cu = 300 ± 100 meV ) and can be understood on the basis of the considerably flatter potential energy landscapes encountered by Ag and Au adatoms on the MoS2 surface (corrugation of the order of tens of meV), as compared to Cu adatoms (corrugation > 100 meV ). Moreover, evaluation of the electronic and magnetic properties of AIMD configurations suggest that Ag, Au, and Cu monomer adsorption induces semimetallic features in at least one spin channel of the adatom/MoS2 electronic structure at elevated temperatures. The overall results presented herein may provide insights into fabricating 2D-material-based heterostructure devices beyond graphene.

  • 23.
    Zhang, Shi-Li
    et al.
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Smith, U.
    Self-aligned silicides for ohmic contacts in complementary metal-oxide-semiconductor technology: TiSi2, CoSi2 and NiSi2004In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 22, no 4, p. 1361-1370Article in journal (Refereed)
    Abstract [en]

    Metal silicides continue to play an indispensable role during the remarkable development of microelectronics. Along with several other technological innovations, the implementation of the self-aligned silicide technology paved the way for a rapid and successful miniaturization of device dimensions for metal-oxide-semiconductor field-effect transistors (MOSFETs) in pace with the Moore's law. The use of silicides has also evolved from creating reliable contacts for diodes, to generating high-conductivity current paths for local wiring, and lately to forming low-resistivity electrical contacts for MOSFETs. With respect to the choice of silicides for complementary metal-oxide- semiconductor (CMOS) technology, a convergence has become clear with the self-alignment technology using only a limited number of silicides, namely TiSi2, CoSi2, and NiSi. The present work discusses the advantages and limitations of TiSi2, CoSi2, and NiSi using the development trend of CMOS technology as a measure. Specifically, the reactive diffusion and phase formation of these silicides in the three terminals of a MOSFET, i.e., gate, source, and drain, are analyzed. This work ends with a brief discussion about future trends of metal silicides in micro/nanoelectronics with reference to potential material aspects and device structures outlined in the International Technology Roadmap for Semiconductors.

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