Browsing by Author "Lu, Chia-Ling"

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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.
Correlation between the Microstructures of Bonding Interfaces and the Shear Strength of Cu-to-Cu Joints Using (111)-Oriented and Nanotwinned Cu
(2018-12-01)
Juang, Jing-Ye
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Lu, Chia-Ling
;
Li, Yu-Jin
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Tu, K. N.
;
Chen, Chih
Highly (111)-oriented Cu pillar-bumps were bonded to highly (111)-oriented Cu films at temperatures ranging from 200 degrees C/100 degrees C to 350 degrees C/100 degrees C in N-2 ambient conditions. The microstructures of the bonded interfaces affected the shear strength performance of the bonded Cu joints. The bonded interfaces at 300 degrees C/100 degrees C and 350 degrees C/100 degrees C had far fewer voids than interfaces bonded at 200 degrees C/100 degrees C and 250 degrees C/100 degrees C. In addition, grain growth took place across the bonding interfaces at temperatures above 300 degrees C/100 degrees C. The corresponding orientation map (OIM) showed the preferred orientation of large grown grains to be <100>. Shear tests revealed that the fracture mode was brittle for joints bonded at 200 degrees C/100 degrees C, but became ductile after bonded above 300 degrees C/100 degrees C. Based on the results, we found that voids and grain growth behavior play import roles in the shear strength performance of bonded Cu joints.
Effect of grain orientations of Cu seed layers on the growth of < 111 >-oriented nanotwinned Cu
(2014-08-19)
Liu, Chien-Min
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Lin, Han-Wen
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Lu, Chia-Ling
;
Chen, Chih
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材料科學與工程學系
We investigate the growth of Cu films on two different Cu seed layers: one with regular < 111 >-oriented grains and the other with very strong < 111 >-preferred orientation. It is found that densely-packed nanotwinned Cu (nt-Cu) can be grown by pulsed electroplating on the strong < 111 >-oriented Cu seed layer without a randomly-oriented transition layer between the nt-Cu and the Cu seed layer. The electroplated nt-Cu grow almost epitaxially on the seed layer and formed < 111 >-oriented columnar structures. However, with the regular < 111 >-oriented Cu seed, there is a randomly-oriented transition layer between the nt-Cu and the regular < 111 >-oriented Cu seed. The results indicate that the seed layer plays a crucial role on the regularity of < 111 >-oriented nanotwinned Cu.
Electrochemical performance of graphite anode with various electrode compressibilities for long-life Li-ion battery
(2015-10-01)
Deng, Min-Jen
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Tsai, Du-Cheng
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Lu, Chia-Ling
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Li, Ching-Fei
;
Shieu, Fuh-Sheng
The effect of electrode compressibility for discharge rate and cycle performance on the natural graphite (NG) anode in Li-ion batteries was studied. Roll-pressing the NG electrode increases electrical contact, which benefits the high discharge rate. However, high roll pressing of NG electrodes accumulates stress and limits the volume increase, thereby leading to poor cyclability. The mixture of NG and mesocarbon microbeads (MCMBs) provides more appropriate electrical contact and exhibits excellent cycle performance as compared to pure NG and MCMB. Therefore, NG-MCMB composite electrodes may emerge as practical and promising anode materials for secondary Li-ion batteries.
Extremely anisotropic single-crystal growth in nanotwinned copper
(2014-10-01)
Lu, Chia-Ling
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Lin, Han-Wen
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Liu, Chien-Min
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Huang, Yi-Sa
;
Lu, Tien-Lin
By electroplating of nearly unidirectionally < 111 >-oriented nanotwinned and fine-grained Cu on a Si wafer surface followed by annealing at 400-500 degrees C for up to 1 h, we grew many extremely large < 100 >-oriented single crystals of Cu with sizes ranging from 200 to 400 mu m. By patterning and annealing the nanotwinned Cu films, we grew an array of < 100 >-oriented single crystals of Cu with sizes ranging from 25 to 100 mu m on Si. In comparison, single-crystal nano-wire growth is a one-dimensional anisotropic growth process, in which the growth along the axial direction is much faster than in the radial direction. We report here a bulk-type two-dimensional crystal growth of an array of numerous < 100 >-oriented single crystals of Cu on Si. This growth process has the potential for microbump applications in three-dimensional integrated circuit-packaging technology for hand-held consumer electronic products.
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
Fabrication of arrays of (100) Cu under-bump-metallization for 3D IC packaging
(2015)
Chiu, Wei-Lan
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Lu, Chia-Ling
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Lin, Han-Wen
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Liu, Chien-Min
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Huang, Yi-Sa
Due to the thousands of microbumps on a chip for 3D ICs, the precise control of the microstructure of all the material is required. The nearly < 111 >-oriented nanotwinned and fine-grained Cu was electroplated on a Si wafer surface and annealed at 400-500 C for 1 h, many extremely large < 100 > oriented Cu crystals with grain sizes ranging from 200 to 400 um were obtained. The < 111 >-oriented Cu grains were transformed into super-large < 100 >-oriented grains after the annealing. In addition, we patterned the < 111 >-oriented Cu films into pad arrays of 25 to 100 um in diameter and annealed the nanotwinned Cu pads with same conditions. An array of < 100 >-oriented single crystals Cu pads can be obtained. Otherwise, single-crystal nano wire growth displays a process by one-dimensional anisotropic growth, in which the growth along the axial direction is much faster than in the radial direction. This study reported here a bulk-type two-dimensional crystal growth of an array of numerous < 100 >-oriented single crystals of Cu on Si. The growth process in 3D IC has the potential for microbump applications packaging technology.
Growth Mechanism of Self-Assembled TixWyO Nanotubes Fabricated by TiW Alloy Anodization
(2018-01-01)
Chang, Yung-Huang
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Chen, Yuan-Tsung
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Huang, Chien-Sheng
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Lu, Chia-Ling
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Lee, Shih-Hung
Nanostructures, such as nanodots and nanorods, have been fabricated by the anodization process with an aid of anodic aluminum oxide (AAO) for several decades. However, tubular nanostructures have not been reported by using an AAO-assistant anodization technology until now. In this study, we successfully synthesized self-organized TixWyO nanotubes with cap structures for the first time by using a two-step anodization process from Al-coated TiW alloy layers. The TixWyO nanotubes were observed only in the shaped pores of AAO with large enough pore size, and otherwise the nanostructures would become solid rods due to the aggregation of TixWyO. The wall of nanotubes was similar to 30% inside the pores and the other similar to 70% penetrated into the AAO template. Furthermore, no tubular nanostructures were found unless the percentage of W element in TiW alloys is larger than 50%, attributing to the formation of a void by oxygen bubbles arising from the oxidation reaction of tungsten metal. Besides, the height of the nanotubes is limited by an electric field of 0.82 GV/m due to the dielectric breakdown effect. Finally, a bottom-up growth mechanism at the oxide/metal interface is proposed, based on the observation of the cap structure on the top of the tubular architecture. (C) The Author(s) 2018. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License.
Low temperature Cu-Cu direct bonding by (111) oriented nano-twin Cu
(2017-01-01)
Juang, Jing-Ye
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Chu, Yi-Cheng
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Lu, Chia-Ling
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Chen, Chih
;
Tu, King-Ning
In this study, a low temperature solid state diffusion bonding process with (111) highly oriented nano-twined Cu (nt-Cu) was proposed. A less void bonding interface was observed reveals a good bonding quality for the bonded samples. In addition, a large quasisingle grain was identified in the bonded film. Based on these results, it is believed that high strength and durable bonding structure can be accomplished by bonding two highly (111)-oriented nt-Cu films.
Unidirectional Growth of Microbumps on (111)-Oriented and Nanotwinned Copper
(2012-05-25)
Hsiao, Hsiang-Yao
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Liu, Chien-Min
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Lin, Han-Wen
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Liu, Tao-Chi
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Lu, Chia-Ling
Highly oriented [111] Cu grains with densely packed nanotwins have been fabricated by direct-current electroplating with a high stirring rate. The [111]-oriented and nanotwinned Cu (nt-Cu) allow for the unidirectional growth of Cu6Sn5 intermetallics in the microbumps of three-dimensional integrated-circuit packaging; a uniform microstructure in a large number of microbumps of controlled orientation can be obtained. The high-density twin boundaries in the nt-Cu serve as vacancy sinks during the solid-state reaction between Pb-free solder and Cu and greatly reduce the formation of Kirkendall (or Frenkel) voids.