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Sputter Rate Distribution and Compositional Variations in Films Sputtered from Elemental and Multi-Element Targets at Different Pressures
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
2014 (English)In: International Journal of Materials Science and Applications, ISSN 2327-2635, Vol. 3, no 2, 29-36 p.Article in journal (Refereed) Published
Abstract [en]

We report on the quantitative dependence of the deposition rate during magnetron sputtering as a function of the atomic mass, processing pressure and substrate location relative to the target. Targets made of four different materials (C, Al, Ti and Ta), ranging from very light to rather heavy atomic masses, were investigated theoretically initially to determine the deposition rate distribution of the sputtered atoms. In the second part, targets made of different combinations of these materials (Ta/C, Ta/Al, Ta/Ti and Ti/Al) were sputtered to investigate the compositional variations of deposited films. The different targets were sputtered at both low (0.27 Pa) and high (2.7 Pa) pressures, and both the deposition rates and compositions were determined at four different locations in the chamber. Further, Monte Carlo simulations were performed for the sputtered atoms in a simplified model of the vacuum chamber. Simulation and experiments are in adequate agreement and show a significant influence of the processing pressure on the deposition rate in various locations of the chamber. This effect is different for different target compositions and may sometimes result in very large compositional variations in films sputtered from segmented multi-element or alloy targets. Transport phenomena of the sputtered particles are also discussed based on a ballistic or diffusion-like process, depending on the sputtering pressure, mass and size of the sputtered atom as well as location in the deposition chamber. Since the materials studied range from light to heavy and the processing pressures cover the values where sputtering normally takes place, the results in this work can be extrapolated to predict the deposition profiles and compositional gradients for arbitrary material combinations and processing pressures.

Place, publisher, year, edition, pages
2014. Vol. 3, no 2, 29-36 p.
National Category
Condensed Matter Physics Nano Technology Other Materials Engineering
Research subject
Engineering Science with specialization in Electronics
URN: urn:nbn:se:uu:diva-220583DOI: 10.11648/j.ijmsa.20140302.14OAI: oai:DiVA.org:uu-220583DiVA: diva2:705691
Available from: 2014-03-17 Created: 2014-03-17 Last updated: 2014-09-08Bibliographically approved
In thesis
1. Sputtering and Characterization of Complex Multi-element Coatings
Open this publication in new window or tab >>Sputtering and Characterization of Complex Multi-element Coatings
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The thin film technology is of great importance in modern society and is a key technology in wide spread applications from electronics and solar cells to hard protective coatings on cutting tools and diffusion barriers in food packaging. This thesis deals with various aspects of thin film processing and the aim of the work is twofold; firstly, to obtain a fundamental understanding of the sputter deposition and the reactive sputter deposition processes, and secondly, to evaluate sputter deposition of specific material systems with low friction properties and to improve their performance.From studies of the reactive sputtering process, two new methods of eliminating the problematic and undesirable hysteresis effect were found. In the first method it was demonstrated that an increased process pressure caused a reduction and, in some cases, even elimination of the hysteresis. In the second method it was shown that sufficiently high oxide content in the target will eliminate the hysteresis.

Further studies of non-reactive magnetron sputtering of multi-element targets at different pressures resulted in huge pressure dependent compositional gradients over the chamber due to different gas phase scattering of the elements. This has been qualitatively known for a long time but the results presented here now enable a quantitative estimation of such effects. For example, by taking gas phase scattering into consideration during sputtering from a WS2 target it was possible to deposit WSx films with a sulphur content going from sub-stoichiometric to over-stoichiometric composition depending on the substrate position relative the target.

By alloying tungsten disulphide (WS2) with carbon and titanium (W-S-C-Ti) its hardness was significantly increased due to the formation of a new titanium carbide phase (TiCxSy). The best sample increased its hardness to 18 GPa (compared to 4 GPa for the corresponding W-S-C coating) while still maintaining a low friction (µ=0.02) due to the formation of easily sheared WS2 planes in the wear track. 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 74 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1162
thin film, coating, magnetron sputtering, modelling, tribofilm, tungsten disulphide
National Category
Other Physics Topics
urn:nbn:se:uu:diva-229207 (URN)978-91-554-8997-7 (ISBN)
Public defence
2014-09-26, Polhemsalen, Ångströmslaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:00 (English)
Swedish Foundation for Strategic Research , 30003
Available from: 2014-09-02 Created: 2014-08-05 Last updated: 2014-09-08

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