Effect of De-Twinning on Tensile Strength of Nano-Twinned Cu Films

Chia-Hung Lee; Erh-Ju Lin; Jyun-Yang Wang; Yi-Xuan Lin; Chen-Yu Wu; Chung-Yu Chiu; Ching-Yu Yeh; Bo-Rong Huang; Kuan-Lin Fu; Cheng-Yi Liu

doi:10.3390/nano11071630

Nanomaterials (Jun 2021)

Effect of De-Twinning on Tensile Strength of Nano-Twinned Cu Films

Chia-Hung Lee,
Erh-Ju Lin,
Jyun-Yang Wang,
Yi-Xuan Lin,
Chen-Yu Wu,
Chung-Yu Chiu,
Ching-Yu Yeh,
Bo-Rong Huang,
Kuan-Lin Fu,
Cheng-Yi Liu

Affiliations

Chia-Hung Lee: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan
Erh-Ju Lin: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan
Jyun-Yang Wang: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan
Yi-Xuan Lin: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan
Chen-Yu Wu: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan
Chung-Yu Chiu: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan
Ching-Yu Yeh: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan
Bo-Rong Huang: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan
Kuan-Lin Fu: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan
Cheng-Yi Liu: Department of Chemical Engineering and Materials Engineering, National Central University, Jhong-Li 32001, Taiwan

DOI: https://doi.org/10.3390/nano11071630
Journal volume & issue: Vol. 11, no. 7
p. 1630

Abstract

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Tensile tests were carried on the electroplated Cu films with various densities of twin grain boundary. With TEM images and a selected area diffraction pattern, nano-twinned structure can be observed and defined in the electroplated Cu films. The density of the nano-twin grain structure can be manipulated with the concentration of gelatin in the Cu-sulfate electrolyte solution. We found that the strength of the Cu films is highly related to the twin-boundary density. The Cu film with a greater twin-boundary density has a larger fracture strength than the Cu film with a lesser twin-boundary density. After tensile tests, necking phenomenon (about 20 μm) occurred in the fractured Cu films. Moreover, by focused ion beam (FIB) cross-sectional analysis, the de-twinning can be observed in the region where necking begins. Thus, we believe that the de-twinning of the nano-twinned structure initiates the plastic deformation of the nano-twinned Cu films. Furthermore, with the analysis of the TEM images on the nano-twinned structure in the necking region of the fractured Cu films, the de-twinning mechanism attributes to two processes: (1) the ledge formation by the engagement of the dislocations with the twin boundaries and (2) the collapse of the ledges with the opposite twin-boundaries. In conclusion, the plastic deformation of nano-twinned Cu films is governed by the de-twinning of the nano-twinned structure. Moreover, the fracture strength of the nano-twinned Cu films is proportional to the twin-boundaries density.

Published in Nanomaterials

ISSN: 2079-4991 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science: Chemistry
Website: https://www.mdpi.com/journal/nanomaterials

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