Browsing by Author "Huang, Yi-Sa"

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An organic hydrogel film with micron-sized pillar array for real-time and indicator-free detection of Zn(2+)
(2011-11-01)
Chao, Yu-Chiang
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Huang, Yi-Sa
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Wang, Hsin-Ping
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Fu, Ssu-Ming
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Huang, Chien-Hao
A hydrogel sensing film for a real-time and indicator-free detection of Zn(2+) is developed by embedding a fluorescent indicator 11,16-bis( phenyl)-6,6,21,21-tetramethyl-m-benzi-6,21-porphodimethene in a hydrogel host poly(2-hydroxyethyl methacrylate). The sensing film shows high stability and selectivity to Zn(2+). The sensitivity of the sensing film is increased by fabricating a micron-sized pillar array on the surface of the sensing film to increase the surface area. For Zn(2+) concentrations of 10 (4) and 10 (3) M, the response time is 30 and 3 s, respectively. (C) 2011 Elsevier B.V. All rights reserved.
An organic hydrogel film with micron-sized pillar array for real-time and indicator-free detection of Zn2+
(2011-11-01)
Chao, Yu-Chiang
;
Huang, Yi-Sa
;
Wang, Hsin-Ping
;
Fu, Ssu-Ming
;
Huang, Chien-Hao
A hydrogel sensing film for a real-time and indicator-free detection of Zn2+ is developed by embedding a fluorescent indicator 11,16-bis( phenyl)-6,6,21,21-tetramethyl-m-benzi-6,21-porphodimethene in a hydrogel host poly(2-hydroxyethyl methacrylate). The sensing film shows high stability and selectivity to Zn2+. The sensitivity of the sensing film is increased by fabricating a micron-sized pillar array on the surface of the sensing film to increase the surface area. For Zn2+ concentrations of 10 (4) and 10 (3) M, the response time is 30 and 3 s, respectively. (C) 2011 Elsevier B.V. All rights reserved.
Concentration Gradient of Ni in Reduced SnAg Thickness in Ni/SnAg/Cu Microbumps during Solid-State Aging
(2013)
Liu, Tao-Chi
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Huang, Yi-Sa
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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
We investigate the cross-interaction in Cu/SnAg/Ni microbumps with a reduced solder thickness of 30 and 10 mu m. The concentration of Ni atoms at the opposite site increased with the decrease in solder-height. A considerable concentration gradient of Ni was detected in 10-mu m microbumps sample, which strongly triggers the diffusion of Ni atoms to the Cu side. The diffused Ni atoms at Cu side form the ternary intermetallic compounds of (Cu,Ni)(6)Sn-5, which possesses a lower free energy than Cu6Sn5 does. Eventually, the growth of the Cu3Sn was inhibited due to the formation of the thermodynamically stable (Cu, Ni) 6Sn5. (C) 2012 The Electrochemical Society. All rights reserved.
Eliminate Kirkendall voids in solder reactions on nanotwinned copper
(2013-03-01)
Liu, Tao-Chi
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Liu, Chien-Min
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Huang, Yi-Sa
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Chen, Chih
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Tu, King-Ning
Electroplating was used to fabricate a high density of nanotwins that exhibited the preferred (111) orientation in Cu. We found no formation of Kirkendall voids in solder reactions on the nanotwinned Cu. This was due to the high density of steps and kinks on the nanotwin boundaries, which serve as vacancy sinks. Thus the vacancy concentration cannot reach supersaturation and nucleate voids. The finding is a significant advance in the problem of solder joint reliability in microelectronic three-dimensional integrated circuit devices. (c) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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
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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 and Characterization of (111)-Oriented and Nanotwinned Cu by Dc Electrodeposition
(2012-10-01)
Liu, Tao-Chi
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Liu, Chien-Min
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Hsiao, Hsiang-Yao
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Lu, Jia-Ling
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Huang, Yi-Sa
We report an approach to fabricating (111)-oriented and nanotwinned Cu (nt-Cu) by dc electroplating. A 200 nm thick Cu with (111) preferred orientation is required as a seed layer. Highly oriented Cu films with densely packed nanotwins can be grown to exceed 20 mu m thick at high current and high stirring speeds. X-ray diffraction indicates that the intensity ratio of (111) to (220) is as high as 506, which is the highest among the reported electroplated Cu films. The spacing of twins ranges from 10 to 100 nm, which reveals a high hardness value of 2.23 GPa. The (111)-oriented nt-Cu will have many potential applications in interconnects and 3D IC packaging.
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.
Formation Mechanism of Porous Cu3Sn Intermetallic Compounds by High Current Stressing at High Temperatures in Low-Bump-Height Solder Joints
(2016-01-01)
Lin, Jie-An
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Lin, Chung-Kuang
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Liu, Chen-Min
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Huang, Yi-Sa
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Chen, Chih
Electromigration tests of SnAg solder bump samples with 15 m bump height and Cu under-bump-metallization (UBM) were performed. The test conditions were 1.45 x 10(4) A/cm(2) at 185 degrees C and 1.20 x 10(4) A/cm(2) at 0 degrees C. A porous Cu3Sn intermetallic compound (IMC) structure was observed to form within the bumps after several hundred hours of current stressing. In direct comparison, annealing alone at 185 degrees C will take more than 1000 h for porous Cu3Sn to form, and it will not form at 170 degrees C even after 2000 h. Here we propose a mechanism to explain the formation of this porous structure assisted by electromigration. The results show that the SnAg bump with low bump height will become porous-type Cu3Sn when stressing with high current density and high temperature. Polarity effects on porous Cu3Sn formation is discussed.
Grain growth in electroplated (111)-oriented nanotwinned Cu
(2014-10-15)
Huang, Yi-Sa
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Liu, Chien-Min
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Chiu, Wei-Lan
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Chen, Chih
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材料科學與工程學系
The grain growth of pulse-plated (111)-oriented nanotwinned Cu (nt-Cu) was investigated at 200-350 degrees C. The results indicate that after the annealing, the nt-Cu exhibits good thermal stability, and columnar grains with a (111)-oriented nt-Cu structure are maintained up to 300 degrees C. The columnar grains consume the original fine-grained region at the bottom of the sample. In addition, these fine grains were converted into nanotwinned columnar grains with a (111) orientation. The electroplated Cu film possessed extremely high (111) preferred orientation after the annealing. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
LOW-TEMPERATURE AND LOW-PRESSURE DIRECT COPPER-TO-COPPER BONDING BY HIGHLY (111)-ORIENTED NANOTWINNED CU
(2016)
Chen, Chih
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Liu, Chien-Min
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Lin, Han-Wen
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Huang, Yi-Sa
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Chu, Yi-Cheng
As the size of microbumps continues to shrink, the amount of solder decreases gradually, resulting the brittleness of solder joints due to formation of intermetallic compounds. Low-temperature Cu-to-Cu direct bonding appears to be one of the solutions for fine-pitch microbumps for 3D IC packaging. However, the high bonding temperature and pressure are the main problems of this approach. We achieve low-temperature Cu-to-Cu direct bonding at low pressure and ordinary vacuum. In addition, the cleaning process is simple. To bond the electroplated Cu films, the samples were cut into 3 x 3-mm(2) pieces. Then, the pieces were cleaned in acetone for 5 min, dried with a N-2 purge, cleaned with a mixed solution of HCl and deionized water (DI) water for 30 sec, rinsed with DI water, and purged with N-2 gas again. 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, or at 200 degrees C at for 30 min. The temperature is lower than the reflow temperature of 250 degrees C for most Pb-free solders. We achieve low-temperature bonding using electroplate highly (111)-oriented nanotwinned Cu (nt-Cu) films. Excellent bonding interface can be accomplished by bonding two highly (111)-oriented nt-Cu films. In addition, excellent interface with few voids can be achieved between a highly (111)-oriented nt-Cu film and a randomly-oriented Cu film. Our breakthrough is based on the finding that the (111) orientation of the Cu surface is critical for bonding. The diffusivity of Cu atoms on (111) surfaces is approximately 3-4 orders higher than other major planes. The (111) plane allows for fast surface diffusion, which enables low-temperature creep to occur. The bonded interface between two (111) surfaces forms a twist-type grain boundary (GB). If the GB has a low angle, it has a hexagonal network of screw dislocations. The hexagonal network image was obtained by plan-view transmission electron microscopy. A simple kinetic model of surface creep will be presented. Our breakthrough provide a potential solution with a huge impact to the interconnect materials in 3D IC. The detail results will be presented in the conference.
Low-temperature direct copper-to-copper bonding enabled by creep on (111) surfaces of nanotwinned Cu
(2015-05-12)
Liu, Chien-Min
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Lin, Han-Wen
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Huang, Yi-Sa
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Chu, Yi-Cheng
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Chen, Chih
Direct Cu-to-Cu bonding was achieved at temperatures of 150-250 degrees C using a compressive stress of 100 psi (0.69 MPa) held for 10-60 min at 10(-3) torr. The key controlling parameter for direct bonding is rapid surface diffusion on (111) surface of Cu. Instead of using (111) oriented single crystal of Cu, oriented (111) texture of extremely high degree, exceeding 90%, was fabricated using the oriented nano-twin Cu. The bonded interface between two (111) surfaces forms a twist-type grain boundary. If the grain boundary has a low angle, it has a hexagonal network of screw dislocations. Such network image was obtained by plan-view transmission electron microscopy. A simple kinetic model of surface creep is presented; and the calculated and measured time of bonding is in reasonable agreement.
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.