Browsing by Author "Lin, Han-wen"

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Effect of Sn Grain Orientation on Formation of Cu6Sn5 Intermetallic Compound Under Current Stressing
(2017-04-01)
Chen, Ming-Yao
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Lin, Han-wen
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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
Solder joints with Cu/Sn-Ag/Cu structure and bump height of 15 mu m have been used to investigate the electromigration phenomenon at different temperatures and current densities. Moreover, the grain orientation was analyzed using electron backscatter diffraction. It was found that the anisotropic properties of tin affected the formation rate of Cu-Sn intermetallic compounds (IMCs), and that the angle between the electron flow direction and tin grain orientation played an important role in the formation of Cu6Sn5 IMC. With changes in angle, the diffusion rate of copper atoms in tin also varied. When the c-axis of tin was parallel to the electron flux, copper atoms diffused rapidly, resulting in fast formation of Cu-Sn IMCs. On the other hand, if the angle between the c-axis of the grain and the electron flow direction was large, the tin grains were more resistant to Cu diffusion during current stressing, leading to a very slow IMC formation rate.
Effects of electromigration on grain rotation behavior of SnAg solders
(2009)
Lin, Han-wen
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Chen, Chih
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Kuo, J. C.
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Chen, C. C.
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材料科學與工程學系
The requirement for smaller devices but with much greater performance leads to a boost in current density and damage caused by electromigration. Recently, some researches show that the grain orientation changes during current stressing. In this study, the solder of SnAg2.6 with 2um-thick UBM layer of Ni and 20um-thick copper pad is used. Electron Backscattered Diffraction (EBSD) is applied to investigate the grain orientation in the entire solder joint during electromigration. Semi-In-situ observations are to determine the rate of change on grain orientation of tin. We can analysis these data at the same time to understand the relationship between the rotation rate of tin grain orientations and the current density applied on it. The analysis for current density in solders is accomplished by finite element simulation result. So far, based on our preliminary result, there are obvious grain rotations when they are subjected to current stressing and detailed results will be presented in the conference.
Fabrication of (111) nanotwinned Cu and its applications in interconnects of microelectronic devices
(2016)
Chen, Chih
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Liu, Chien-Min
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Lu, Tien-Lin
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Lin, Han-wen
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Chu, Yi-Cheng
Low-temperature and low pressure copper-to-copper direct bonding enabled by creep on highly (111)-oriented Cu surfaces
(2015)
Tseng, Chih-Han
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Liu, Chien-Min
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Lin, Han-wen
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Chu, Yi-Cheng
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Chen, Chih
Cu-to-Cu microbumps have many advantages, such as better electrical and thermal conductivities. The Cu-to-Cu microbumps may be a potential solution to the heat dissipation problem in 3D IC integration. In addition, for packaging of CMOS image sensors, the bonding temperature is preferred to below 200 degrees C. Therefore, low temperature and low pressure Cu-to-Cu direct is of great interests for packaging industry. However, it is a challenging issue because Cu atoms diffuse slowly below 200 degrees C. In this study, we achieved low temperature and low pressure Cu bonding using highly (111)-orientated Cu films. Because the diffusivity of Cu atoms on the (111) surface diffusivity is the fastest among all the crystallographic planes of Cu. The bonding temperature can be lowered to 150 degrees C at a compressive stress of 114 psi held for 60 min at 10-3 torr. Since the melting points of popular Pb-free solders such as SnAg and SnAgCu are over 230 degrees C. Therefore the present technique can be applied to packaging of CMOS image sensors and 3D IC integration.
Microstructure control of unidirectional growth of eta-Cu6Sn5 in microbumps on < 1 1 1 > oriented and nanotwinned Cu
(2013-08-01)
Lin, Han-wen
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Lu, Chia-ling
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Liu, Chien-min
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Chen, Chih
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Chen, Delphic
Anisotropic microstructure is becoming a critical issue in microbumps used in 3-D integrated circuit packaging. We report here an experimental approach for controlling the microstructure of eta-Cu6Sn5 intermetallic compound in microbumps by using < 1 1 1 > oriented and nanotwinned Cu pads as the under-bump-metallization. By electroplating arrays of large numbers of < 1 1 1 > oriented and nanotwinned Cu pads and by electroplating the Sn2.3Ag solder on the pads, we form eta-Cu6Sn5 in the reflow at 260 degrees C for 1 min. The eta-Cu6Sn5 showed a highly preferential growth along the < 0 0 0 1 > direction. As reflow time is extended, the preferred texture of eta-Cu6Sn5 changed to {2 (1) over bar (1) over bar 3}. The results indicate that we can control the uniform microstructure of eta-Cu6Sn5 intermetallic by controlling the microstructure of the Cu under-bump-metallization. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
The preferential growth of eta-Cu6Sn5 on (111) uni-directional Cu pads
(2012)
Lin, Han-wen
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Lu, Jia-ling
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Liu, Chen-min
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Chen, Chih
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Tu, King-ning