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Growth of TiC/a-C:H nanocomposite films by reactive high power impulse magnetron sputtering under industrial conditions
Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics.ORCID iD: 0000-0003-2864-9509
Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, Sweden.
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2012 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 8-9, 2396-2402 p.Article in journal (Refereed) Published
Abstract [en]

Titanium carbide (TiC) films were deposited employing high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) in an Ar-C2H2 atmosphere of various compositions. Analysis of the structural, bonding and compositional characteristics revealed that the deposited films are nanocomposites; either hydrogenated amorphous carbon and TiC (TiC/a-C:H), or Titanium and TiC (Ti/TiC) depending on the C/Ti ratio of the films. It was found that TiC/a-C:H films grown by HiPIMS were dense, and within a certain C2H2 flow range (4-15 sccm) showed little changes in C/Ti ratio, which also saturated towards 1. The HiPIMS grown films also exhibited the tendency to form smaller fractions of amorphous C matrix, and incorporate smaller amounts of oxygen contaminants, as compared to films grown by DCMS. The TiC/a-C:H films exhibited resistivity and hardness values of 4-8×102 μΩcm and 20-27 GPa, respectively when deposited by HiPIMS. The corresponding values for films grown by DCMS at the same deposition rate as HiPIMS were >10×102 μΩcm and ~6-10 GPa respectively, likely due to abundant formation of free C and porosity, allowing oxygen contaminations.

Place, publisher, year, edition, pages
Elsevier, 2012. Vol. 206, no 8-9, 2396-2402 p.
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-67485DOI: 10.1016/j.surfcoat.2011.10.039ISI: 000300458500047OAI: oai:DiVA.org:liu-67485DiVA: diva2:410561
Note

funding agencies|Swedish Research Council (VR)| 621-2005-3245 621-2008-3222 623-2009-7348 |

Available from: 2011-04-14 Created: 2011-04-14 Last updated: 2015-05-28Bibliographically approved
In thesis
1. High power impulse magnetron sputtering under industrial conditions
Open this publication in new window or tab >>High power impulse magnetron sputtering under industrial conditions
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, the recent development step of magnetron sputtering, termed high power impulse magnetron sputtering (HiPIMS) has been studied. Compared to conventional magnetron sputtering HiPIMS provides a higher plasma density which can ionise the sputtered material. The beneficial influence of the coating properties due to this ionisation has been extensively shown in academic publications. Here, industrial conditions, i.e. no substrate heating and high vacuum conditions have been used during the studies, of which one was performed in an industrial deposition system.

For eight metallic targets, films were deposited with HiPIMS and conventional sputtering. The films were evaluated by Rutherford back scattering analysis, scanning electron microscopy, and profilometry. It was found that the density of the HiPIMS grown films exhibited a statistically significant higher density of approximately 5-15% in comparison to films deposited using DCMS under identical conditions. A global plasma model was employed to evaluate the degree of ionisation for some of the target materials, and process conditions used in the study. Conformity between density increase and degree of ionisation as assessed by the plasma model was confirmed.

The influence of using HiPIMS during reactive sputtering of TiC was also studied. A metallic Ti target was sputtered in a gas mixture of Ar and C2H2. The coatings were evaluated by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, 4 point probe resistivity measurements, and nanoindentation. The coatings were found to be nanocomposite TiC/a-C:H. For the HiPIMS process the transition zone between metallic and compound target states was found to be significantly expanded over a wide reactive gas flow range. The implications of choice of deposition method for coating composition, chemical structure, as well as electrical and mechanical properties were evaluated for DCMS and HiPIMS. The process behaviour was suggested to be due to the pulsed nature of the HiPIMS, the high plasma density, and ion content of the particles reaching the substrate.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2011. 45 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1477
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-67487 (URN)LIU-TEK-LIC-2011:16 (Local ID)978-91-7393-194-6 (ISBN)LIU-TEK-LIC-2011:16 (Archive number)LIU-TEK-LIC-2011:16 (OAI)
Presentation
2011-05-17, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:00 (English)
Opponent
Supervisors
Available from: 2011-04-14 Created: 2011-04-14 Last updated: 2013-10-30Bibliographically approved
2. Fundamental aspects of HiPIMS under industrial conditions
Open this publication in new window or tab >>Fundamental aspects of HiPIMS under industrial conditions
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Fundamental aspects of the high power impulse magnetron sputtering (HiPIMS) process and its implication for film growth under industrial conditions have been studied. The emerging HiPIMS technique exhibits a higher plasma density and an enhanced degree of ionisation of sputtered material as compared to conventional direct current magnetron sputtering (DCMS). The increased ionisation permits control of the deposition flux and facilitates an intense ion bombardment of the growing films. The latter allows for growth of well adherent, smooth, and dense thin films. Moreover, the technique offers increased stability of reactive processes, control of film phase constitution as well as tailoring of e.g. optical and mechanical properties.

In the present work, it was shown, for eight different metals (Al, Ti, Cr, Cu, Zr, Ag, Ta, and Pt), that films grown using HiPIMS exhibit a 5-15% higher density than films grown using DCMS under otherwise identical conditions. Through simulations of the fundamental ionisation processes in the plasma discharge, a correlation between high ionisation degree and film densification was established. The densification was suggested to be a consequence of increased ion irradiation of the growing films in the HiPIMS case. This knowledge was used to investigate the degree of ionisation in the deposition flux required for film modifications. Using a hybrid process, where DCMS and HiPIMS were combined on a single Cr cathode, independent control of the degree of ionisation from other experimental parameters was achieved. The results showed that the majority of the ion irradiation induced modifications of surface related film properties occurred when ~40% of the total average power was supplied by the HiPIMS generator. Under such conditions, the power normalised deposition rate was found to be ~80% of that of DCMS. This was attributed to a reduction in back-attracted ionised sputtered material, which is considered to be the main reason for the low deposition rate of HiPIMS. Thus, enhanced film properties were attainable largely without sacrificing deposition rate.

Compound carbide and boride films were synthesised using both reactive processes and compound sources. Reactive deposition of TiC/a-C:H thin films using C2H2 as reactive gas, i.e. carbon source, was demonstrated. It was found that the high plasma density processes (i.e. HiPIMS) facilitated growth conditions for the film structure formation closer to thermodynamic equilibrium than did processes exhibiting lower plasma densities (i.e. DCMS). This was manifested in a high stoichiometry of the carbide phase, whilst excess a-C was removed by physical sputtering. Moreover, the feasibility of using HiPIMS for thin film growth from a compound source, obtaining the same composition in the films as the sputtering source, was demonstrated through synthesis of ZrB2 films.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2012. 52 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1461
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-79306 (URN)978-91-7519-856-9 (ISBN)
Public defence
2012-08-16, Planck, Fysikhuset, Campus Valla, Linköpings univeristet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2012-07-09 Created: 2012-07-09 Last updated: 2013-10-30Bibliographically approved

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Samuelsson, MattiasSarakinos, KostasHögberg, HansHelmersson, Ulf
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