TaWSi amorphous metal thin films: composition tuning to improve thermal stability
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TaWSi amorphous metal thin films: composition tuning to improve thermal stability John M. McGlone, Department of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331-5501, USA Kristopher R. Olsen†, Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA William F. Stickle, Hewlett-Packard Company, Corvallis, Oregon 97333, USA James E. Abbott, 3D NanoColor, 1110 NE Circle Blvd, Corvallis, Oregon 97330, USA Roberto A. Pugliese and Greg S. Long, Hewlett-Packard Company, Corvallis, Oregon 97333, USA Douglas A. Keszler, Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA John F. Wager, Department of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331-5501, USA Address all correspondence to John M. McGlone at [email protected] and [email protected] (Received 12 June 2017; accepted 17 August 2017)
Abstract We deposited TaWSi amorphous metal thin films to determine how composition affects film crystallization and oxidation at high temperatures. Films were deposited by magnetron sputtering from targets of nominal compositions Ta : W : Si = 40 : 40 : 20, 30 : 50 : 20, and 30 : 30 : 40, and studied by electron probe microanalysis, electron microscopy, electrical methods, x-ray diffraction, x-ray photoelectron spectroscopy, and atomic-force microscopy. All films remained amorphous to 800 °C or higher temperatures. Films prepared from the target composition 30 : 30 : 40 yielded the film composition Ta41.7W38.4Si19.9, which retained its film integrity and amorphous structure to 1100 °C, even after annealing in air.
Introduction Numerous applications require thermally robust metal thin films that possess both high strength and corrosion resistance. Examples of high-temperature applications include thermal inkjet printing,[1] pressure sensors in combustion engines,[2] and turbine blade protective coatings.[3] Semiconductor manufacturing also requires thermal stability of metals to 400 °C for back-end-of-line processing[4] and above 1000 °C for gate metal annealing.[5] An amorphous metal thin film (AMTF) is an attractive option for such applications. It lacks the grain boundaries and dislocations of crystalline materials, which degrade mechanical strength and provide pathways for chemical attack. Additionally, an amorphous thin film possesses an ultra-smooth surface when deposited onto a substrate with a smooth surface, a feature that often enhances device performance. These attributes have stimulated interest in their use for many emerging applications.[6,7] Amorphous metals are metastable and prone to crystallize at high temperatures. Once crystallized, their performance advantages are lost. We examine here how to produce new refractory amorphous thin films with high crystallization and oxidation temperatures.
† These authors share first authorship.
Amorphous metals comprising refractory elements, such as Ta, W, or both, are expected t
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