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Appl. Sci. 2018, 8(12), 2403;

The Effect of Interfacial Ge and RF-Bias on the Microstructure and Stress Evolution upon Annealing of Ag/AlN Multilayers

Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Joining Technologies and Corrosion, Überlandstrasse 129, 8600 Dübendorf, Switzerland
Institute of Solid State Physics of the Russian Academy of Sciences, Chernogolovka 142432, Russia
Author to whom correspondence should be addressed.
Current address: Instituto de Tecnología de Materiales, Universitat Politècnica de València Camino de Vera s/n, 46022 Valencia, Spain.
Received: 25 October 2018 / Revised: 21 November 2018 / Accepted: 22 November 2018 / Published: 27 November 2018
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
PDF [23482 KB, uploaded 28 November 2018]


The present study addresses the structural stability and mass outflow of Ag 10 nm/Ge 1 nm/AlN 10 nm nanomultilayers (NMLs) during thermal treatments in different atmospheres (Ar and air). The nanomultilayers were obtained by magnetron sputtering under different deposition conditions (with and without the RF (Radio-Frequency)-bias application). The microstructure of the as-deposited and thermally treated NMLs were analyzed by XRD and SEM techniques, deriving morphology, microstructure and internal stress. Bias application during the deposition is found to create highly disordered interfaces and to have a very strong influence on the morphology and structural evolution with temperature of the nano-multilayers. Complete multilayer degradation is observed for the bias sample when annealed in Ar at 700 C, while the periodic multilayer structure is preserved for the non-bias samples. Structural and morphological changes are observed starting from 400 C, accompanied with Ag surface migration. The highest Ag amount on the surface is detected in air atmosphere for bias and non-bias samples annealed at temperatures as high as 700 C. The presence of Ge is found to strongly hinder the Ag surface migration. Ag outflow is measured to take place only through the network of surface cracks in the AlN barrier formed upon heating. The crack formation and Ag migration are discussed together with the stress relaxation. The present study demonstrates the feasibility to tailor the stress state of as-deposited NML structures and observe different structural evolution depending on the initial conditions. This paves the way for advanced experimental strategies to tailor directional mass outflow in nanoconfined filler systems for advanced nano-joining applications. View Full-Text
Keywords: nanomultilayer; morphological stability; microstructure; PVD layers; stress; thermal stability nanomultilayer; morphological stability; microstructure; PVD layers; stress; thermal stability

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Cancellieri, C.; Klyatskina, E.; Chiodi, M.; Janczak-Rusch, J.; Jeurgens, L.P.H. The Effect of Interfacial Ge and RF-Bias on the Microstructure and Stress Evolution upon Annealing of Ag/AlN Multilayers. Appl. Sci. 2018, 8, 2403.

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