Browsing by Author "Shen, Yu-An"

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Anisotropic Grain Growth in (111) Nanotwinned Cu Films by DC Electrodeposition
(2020-01-01)
Lu, Tien-Lin
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Shen, Yu-An
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Wu, John A.
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Chen, Chih
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材料科學與工程學系
We have reported a method of fabricating (111)-orientated nanotwinned copper (nt-Cu) by direct current electroplating. X-ray analysis was performed for the samples annealed at 200 to 350 degrees C for an hour. X-ray diffraction indicates that the (200) signal intensity increases while (111) decreases. Abnormal grain growth normally results from transformation of surface energy or strain energy density. The average grain size increased from 3.8 mu m for the as-deposited Cu films to 65-70 mu m after the annealing at 250 degrees C for 1 h. For comparison, no significant grain growth behavior was observed by random Cu film after annealing for an hour. This research shows the potential for its broad electric application in interconnects and three-dimensional integrated circuit (3D IC) packaging.
Effect of Sn grain orientation on formation of Cu6Sn5 intermetallic compounds during electromigration
(2017-02)
Shen, Yu-An
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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
The effects of Sn orientation and grain boundary misorientation on formation of Cu-Sn intermetallic compounds (IMCs) during electromigration were investigated. Significant anisotropic diffusion of Cu in Sn grains was observed. Interfacial Cu-Sn IMCs may grow rapidly, dissolve, or remain intact, depending on the angle of c-axis of Sn grains with the electron flow. In addition, grain boundaries did not play an important role in Cu diffusion because they are mostly cyclic twins. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Effect of Sn grain orientation on growth of Cu-Sn intermetallic compounds during thermomigration in Cu-Sn2.3Ag-Ni microbumps
(2019-02-01)
Shen, Yu-An
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Ouyang, Fan-Yi
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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
The effect of Sn orientation on thermomigration was investigated in Cu/Sn2.3Ag/Ni microbumps with diameter of 20 mu m. Results showed that anisotropic diffusion of Cu in Sn grains affected both formation rates and locations of Cu6Sn5 intermetallic compounds (IMCs). Rapid growth of Cu6Sn5 IMCs at the coldend interface was observed when the c-axis of Sn grains was parallel to the temperature gradient. In addition, diffusion of Cu atoms was blocked by a Sn grain with a high angle between the Sn c-axis and the thermal gradient, resulting in formation of Cu6Sn5 IMCs near the grain boundary inside the solder. (C) 2018 Elsevier B.V. All rights reserved.
Effect of Sn Grain Orientation on the Formation of Cu6Sn5 Intermetallic Compounds during Electromigration
(2016)
Shen, Yu-An
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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
Sn grain orientation that has highly anisotropic diffusivities plays a very important role on thermal-cycling test and electromigration failure. In this study, Cu/Sn-2.3Ag/Cu microbumps, assembled by thermal-compression bonding, after electromigration test are investigated grain orientation by electron-backscattering diffraction (EBSD). The condition of electromigration test is under the current density of 4x104 A/cm2 and 165 degrees C. In the results, The IMC growth at the interface of Cu/solder is very serious as the electron flow along a low alpha-angle grain as Very serious as that along a high alpha-angle grain. Therefore, we demonstrate IMC formations depend on the angle between c-axis and electron flow in Sn grains.
Study of Grain Size and Orientation of 30 mu m Solder Microbumps Bonded by Thermal Compression
(2015)
Shen, Yu-An
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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
Grain size and orientation of microbump play very important roles on thermal-cycling test and electromigration failure. In this study, Cu/Sn-2.5Ag/Cu and Ni/Sn-2.5Ag/Ni microbumps assembled by thermal-compression bonding are investigated grain size and orientation by electron-backscattering diffraction inverse pole figure. Cu/Sn-2.5Ag/Cu microbumps appear much more single crystal-like structures than Ni/Sn-2.5Ag/Ni. By the distribution of grain size, a large quantity of the small Sn grains appears in Ni/Sn-2.5Ag/Ni microbump due to the very low solubility of Ni in Sn. Finally, Cu/Sn-2.5Ag/Cu microbumps possess more grain areas with the lower angles between c-axis and normal dirction.