Browsing by Author "Chen, Kuan-Ju"

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Copper-to-Copper direct bonding on highly (111) oriented nano-twinned copper in no-vacuum ambient
(2017-01-01)
Juang, Jing-Ye
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Lu, Chia-Ling
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Chen, Kuan-Ju
;
Chang, Tao-Chih
;
Chen, Chih
In this study, we achieve the Cu-to-Cu direct bonding by using the (111) oriented nano-twined-Cu in N-2 ambient, without vacuum condition and no additional thermal annealing treatment is needed. A well bonded interface under a temperature gradient between 400 degrees C and 100 degrees C was identified by the evidence of the grown grain across the bonding interface. In addition, a creep assisted bonding mechanism for the Cu-Cu direct bonding is proposed. Moreover, a shear test was applied on the bonded joints for the investigation of the bonded joint strength and its fracture mode. The mean value of joint strength is 176 MPa which is significantly higher than the conventional solder joint. In summary, the Cu-to-Cu direct bonding by (111) oriented nt-Cu in no-vacuum ambient as well as the grain evolution across the bonding interface has been achieved and verified.
Copper-to-copper direct bonding on highly (111)-oriented nanotwinned copper in no-vacuum ambient
(2018-09-17)
Juang, Jing-Ye
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Lu, Chia-Ling
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Chen, Kuan-Ju
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Chen, Chao-Chang A.
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Hsu, Po-Ning
A vacuum-free Cu-to-Cu direct bonding by using (111)-oriented and nanotwinned Cu has been achieved. A fast bonding process occurs in 5 min under a temperature gradient between 450 and 100 degrees C. It is verified by grain growth across the bonded interface. To investigate the grain growth behavior, further annealing in the temperature gradient, as well as in a reversed temperature gradient, was performed. They showed similar recrystallization behavior with de-twinning. To analyze the de-twinning, we recall the classic model of annealing twin formation by Fullman and Fisher as comparison. Our case is opposite to the model of Fullman and Fisher. A mechanism of direct bonding by surface diffusion creep is proposed.
Effect of additives on the microstructures of highly-oriented (111) nanotwinned Cu
(2016)
Chen, Kuan-Ju
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Chen, Chih
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Chen, Zong-Cyuan
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Chung, Stream
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Hung, Chiu-Ming
Effect of Reverse Currents during Electroplating on the < 111 >-Oriented and Nanotwinned Columnar Grain Growth of Copper Films
(2020-06-03)
Chen, Kuan-Ju
;
Wu, John A.
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Chen, Chih
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材料科學與工程學系
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Department of Materials Science and Engineering
Nanotwinned copper (nt-Cu) has been attracting a great deal of attention in the past decades due to its excellent mechanical and electrical properties. In this study, a new approach, periodic-reverse (PR) waveforms, is adopted to electroplate nt-Cu films with highly < 111 >-oriented columnar grain microstructures. We investigate the effect of the reverse current on the microstructures of < 111 >--oriented nt-Cu films and their grain growth behavior. With proper reverse current parameters, we are able to obtain a nt-Cu film with a significantly thin transition layer, low amount of impurities, and low residual stress levels in comparison to a DC electroplated film. It is also discovered that the grain size after annealing of the nt-Cu film is related to its initial columnar grain microstructures, which can be tailored by the reverse current parameter. These results show that PR electroplating provides a promising approach in improving and controlling the microstructures and properties of nt-Cu films.
Ultra-high annealing twin density in < 211 >-oriented Cu films
(2020-07-15)
Chen, Kuan-Ju
;
Chen, Jui-Yuan
;
Ting, Yi-Hsin
;
Wu, Wen-Wei
;
Chen, Chih
We reported the fabrication of densely twinned Cu films with highly (211) texture developed from the annealing of <111>-oriented nanotwinned copper (nt-Cu) films. During the annealing at 300 degrees C, abnormal grain growth occurred in the nt-Cu film and resulted in a microstructure dominated by the anomalously large <211>-oriented grains. Moreover, densely-intersected annealing twin bands with <221>, <611>, and <931> orientations are embedded in the large <211> grains. The measured annealing twin density is 0.2 mu m(-1), which is highest among the reported values in previous literatures with similar grain size. Extensive multiple twinning process may occur during the annealing to form the unique microstructure. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.