Microstructural Effects on the Interfacial Adhesion of Nanometer-Thick Cu Films on Glass Substrates: Implications for Microelectronic Devices.

Content Provider	Europe PMC
Author	Lassnig, Alice Terziyska, Velislava L. Zalesak, Jakub Jörg, Tanja Toebbens, Daniel M. Griesser, Thomas Mitterer, Christian Pippan, Reinhard Cordill, Megan J.
Copyright Year	2020
Abstract	Improvingthe interface stability for nanosized thin films on brittlesubstrates is crucial for technological applications such as microelectronicsbecause the so-called brittle–ductile interfaces limit theiroverall reliability. By tuning the thin film properties, interfaceadhesion can be improved because of extrinsic toughening mechanismsduring delamination. In this work, the influence of the film microstructureon interface adhesion was studied on a model brittle–ductileinterface consisting of nanosized Cu films on brittle glass substrates.Therefore, 110 nm thin Cu films were deposited on glass substratesusing magnetron sputtering. While film thickness, residual stresses,and texture of the Cu films were maintained comparable in the sputteringprocesses, the film microstructure was varied during deposition andvia isothermal annealing, resulting in four different Cu films withbimodal grain size distributions. The interface adhesion of each Cufilm was then determined using stressed Mo overlayers, which triggeredCu film delaminations in the shape of straight, spontaneous buckles.The mixed-mode adhesion energy for each film ranged from 2.35 J/m2 for the films with larger grains to 4.90 J/m2 forthe films with the highest amount of nanosized grains. This surprisingresult could be clarified using an additional study of the bucklesusing focused ion beam cutting and quantification via confocal laserscanning microscopy to decouple and quantify the amount of elasticand plastic deformation stored in the buckled thin film. It couldbe shown that the films with smaller grains exhibit the possibilityof absorbing a higher amount of energy during delamination, whichexplains their higher adhesion energy.
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Journal	ACS Applied Nano Materials [ACS Appl Nano Mater]
Volume Number	4
DOI	10.1021/acsanm.0c02182
PubMed Central reference number	PMC7836095
Issue Number	1
PubMed reference number	33521588
e-ISSN	25740970
Language	English
Publisher	American ChemicalSociety
Publisher Date	2020-12-28
Access Restriction	Open
Rights License	This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. © 2020 AmericanChemical Society
Subject Keyword	thin film adhesion brittle−ductileinterface spontaneous buckles film microstructure nanosizedCu films
Content Type	Text
Resource Type	Article
Subject	Materials Science