TY - JOUR

T1 - Miniaturized fracture experiments to determine the toughness of individual films in a multilayer system

AU - Konetschnik, Ruth

AU - Kozic, Darjan

AU - Schöngrundner, Ronald

AU - Kolednik, Othmar

AU - Gänser, Hans-Peter

AU - Brunner, Roland

AU - Kiener, Daniel

PY - 2016/1/25

Y1 - 2016/1/25

N2 - Recently, the miniaturization of devices in the field of microelectronics has become more and more important. This also implies an increased complexity of the devices, where multilayer thin film systems play a major role. The use of various material combinations leads to the development of residual stresses, potentially causing cracks. Therefore, to prevent failures a thorough understanding of material properties such as the fracture toughness at small scales is indispensable, as these may differ significantly from bulk values. In this study we use miniaturized fracture tests to investigate the fracture behaviour of Cu–W–Cu and W–Cu–W trilayer thin film systems, having a thickness of 500 nm per individual W or Cu layer. The films are subjected to differences in elastic properties and residual stress gradients that both influence the fracture behaviour and thus have to be included in all considerations. We demonstrate that for the W layers a valid -integral can be evaluated. However, we find that the presented advanced treatment does not allow the extraction of valid fracture mechanical quantities for the Cu layers, pointing out the need to develop a more sophisticated approach for ductile materials.

AB - Recently, the miniaturization of devices in the field of microelectronics has become more and more important. This also implies an increased complexity of the devices, where multilayer thin film systems play a major role. The use of various material combinations leads to the development of residual stresses, potentially causing cracks. Therefore, to prevent failures a thorough understanding of material properties such as the fracture toughness at small scales is indispensable, as these may differ significantly from bulk values. In this study we use miniaturized fracture tests to investigate the fracture behaviour of Cu–W–Cu and W–Cu–W trilayer thin film systems, having a thickness of 500 nm per individual W or Cu layer. The films are subjected to differences in elastic properties and residual stress gradients that both influence the fracture behaviour and thus have to be included in all considerations. We demonstrate that for the W layers a valid -integral can be evaluated. However, we find that the presented advanced treatment does not allow the extraction of valid fracture mechanical quantities for the Cu layers, pointing out the need to develop a more sophisticated approach for ductile materials.

KW - Bending beam

KW - Finite element modelling

KW - Fracture toughness

KW - Multilayer

KW - Residual stress

KW - Small scale mechanics

UR - http://www.scopus.com/inward/record.url?scp=84957402198&partnerID=8YFLogxK

U2 - 10.1016/j.eml.2016.01.004

DO - 10.1016/j.eml.2016.01.004

M3 - Article

AN - SCOPUS:84957402198

VL - 8.2016

SP - 235

EP - 244

JO - Extreme Mechanics Letters

JF - Extreme Mechanics Letters

SN - 2352-4316

IS - September

ER -