Browsing by Author "Chiu, Wei-Lan"

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Fabrication of arrays of (100) Cu under-bump-metallization for 3D IC packaging
(2015)
Chiu, Wei-Lan
;
Lu, Chia-Ling
;
Lin, Han-Wen
;
Liu, Chien-Min
;
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 of nearly void-free Cu3Sn intermetallic joints using nanotwinned Cu metallization
(2014-04-28)
Chiu, Wei-Lan
;
Liu, Chien-Min
;
Haung, Yi-Sa
;
Chen, Chih
;
材料科學與工程學系
Cu3Sn intermetallic compounds (IMCs) are more resistant to fracture than solders. In addition, the Cu3Sn IMCs are more conductive than the solders. In this study, we manufactured Cu3Sn IMCs to serve as a joint using electroplated nanotwinned Cu as a metallization layer to react with pure Sn at 260 degrees C and 340 degrees C. The results show that there were almost no Kirkendall voids generated inside the Cu3Sn layer. In addition, the kinetics of the Cu3Sn growth was analyzed to predict the time needed to form the Cu3Sn joint. (C) 2014 AIP Publishing LLC.
Formation of plate-like channels in Cu6Sn5 and Cu3Sn intermetallic compounds during transient liquid reaction of Cu/Sn/Cu structures
(2016-02-01)
Chiu, Wei-Lan
;
Liu, Chien-Min
;
Haung, Yi-Sa
;
Chen, Chih
;
材料科學與工程學系
Transient liquid reactions in Cu/Sn/Cu sandwich structures during various stages were conducted at 340 degrees C. In the early stages of the reaction, Cu atoms dissolved into the molten Sn through the valleys between the scallop-like Cu6Sn5 intermetallic compounds (IMCs). When the Sn layer was almost consumed, formation of plate-like Sn channels in Cu6Sn5 IMCs was observed at later stages of the reaction. In addition, plate-like Cu6Sn5 channels formed in Cu3Sn IMCs because Cu atoms diffused faster in Cu6Sn5 than in Cu3Sn IMCs. These channels serve as fast diffusion paths for Cu to react with the remaining Sn. Hence, the growth kinetics at later stages are quite different from those at the beginning stages. (C) 2015 Elsevier B.V. All rights reserved.
Grain growth in electroplated (111)-oriented nanotwinned Cu
(2014-10-15)
Huang, Yi-Sa
;
Liu, Chien-Min
;
Chiu, Wei-Lan
;
Chen, Chih
;
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.