Crystallinity-induced variation of the yield strength of electroplated copper thin films

Yifan Luo, Kunio Tei, Ken Suzuki, Hideo Miura

Research output: Chapter in Book/Report/Conference proceedingConference contribution

14 Citations (Scopus)


The quality of grains and grain boundaries of polycrystalline copper thin films was analyzed by using image quality (IQ) value obtained from the observed Kikuchi pattern by applying electron back-scatter diffraction (EBSD) analysis. It is considered that the IQ value strongly correlates with the order of atomic configuration in the observed area, in other words, density of various defects, and thus, the area with high IQ value was defined as the area with high crystallinity. The yield strength of a grain was measured by using micro tensile test system in a scanning electron microscope. A bicrystal structure which had two grains with different IQ values was cut from a copper thin film by using focus ion beam (FIB) and the sample was fixed to a single-crystalline silicon beam and a micro probe, respectively, by tungsten deposition. Finally it was thinned to 1µm and stretched to fracture at room temperature. In this micro tensile test, however, the tungsten deposition on the side surface of the test samples caused serious error on the measured strength. Therefore, in this study, the experimental method was improved by the development of an effective method for elimination the excess tungsten deposition. During the tensile test, a mass of plastic deformation and necking phenomenon were obviously observed. Ductile fracture always occurred in the grain with higher Schmidt factor. It was found that the yield strength of a copper grain decreased monotonically with the increase in the IQ value when the IQ value at the grain boundary was larger than 3500.

Original languageEnglish
Title of host publicationMechanics of Solids, Structures and Fluids; NDE, Structural Health Monitoring and Prognosis
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791858448
Publication statusPublished - 2017
EventASME 2017 International Mechanical Engineering Congress and Exposition, IMECE 2017 - Tampa, United States
Duration: 2017 Nov 32017 Nov 9

Publication series

NameASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)


OtherASME 2017 International Mechanical Engineering Congress and Exposition, IMECE 2017
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Mechanical Engineering


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