Analysis of bump resistance and current distribution of ultra-fine-pitch microbumps

Chang, Yuan; Peng, Hsin Ying; Yang, Ruo Wei; Chen, Chih; Chang, T.-P.; Zhan, Cheng; Juang, Jin-Ye; Huang, Ahong

doi:10.1016/j.microrel.2012.08.021

Cited by 13 publications

(3 citation statements)

References 14 publications

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“…Because of the small diameter of microbumps, the difference of cross-section area between the traces and the microbumps was not big. Therefore, the current crowding effect is very slight in the microbumps 21 , 22 . As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Both of them were correlated with the current crowding effect in the FC bumps. The small amount of solder in microbumps did not only reduce the current crowding effect 21 , 22 , it also could be fully transformed into the IMC in a short time. These characteristics significantly elongated the EM failure and caused the microbumps immortal in some specific test conditions 23 – 25 .…”

Section: Introductionmentioning

confidence: 96%

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A new failure mechanism of electromigration by surface diffusion of Sn on Ni and Cu metallization in microbumps

Chang

Hu²,

Peng³

et al. 2018

Sci Rep

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Microbumps in three-dimensional integrated circuit now becomes essential technology to reach higher packaging density. However, the small volume of microbumps dramatically changes the characteristics from the flip-chip (FC) solder joints. For a 20 µm diameter microbump, the cross-section area and the volume are only 1/25 and 1/125 of a 100 µm diameter FC joint. The small area significantly enlarges the current density although the current crowding effect was reduced at the same time. The small volume of solder can be fully transformed into the intermetallic compounds (IMCs) very easily, and the IMCs are usually stronger under electromigration (EM). These result in the thoroughly change of the EM failure mechanism in microbumps. In this study, microbumps with two different diameter and flip-chip joints were EM tested. A new failure mechanism was found obviously in microbumps, which is the surface diffusion of Sn. Under EM testing, Sn atoms tend to migrate along the surface to the circumference of Ni and Cu metallization to form Ni3Sn4 and Cu3Sn IMCs respectively. When the Sn diffuses away, necking or serious void formation occurs in the solder, which weakens the electrical and mechanical properties of the microbumps. Theoretic calculation indicates that this failure mode will become even significantly for the microbumps with smaller dimensions than the 18 µm microbumps.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

A new failure mechanism of electromigration by surface diffusion of Sn on Ni and Cu metallization in microbumps

Chang

Hu²,

Peng³

et al. 2018

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

“…Threedimensional integrated circuit (3-D IC) is believed to be one of the pro missing technologies that can extend Moore's Law by providing high density interconnections. In order to meet the requirements of high density interconnections, small size, fine-p itch microbu mps are widely adopted as interconnects between different chips [1][2][3][4]. Yu et al [5] reported the possibility o f forming microbumps consisting of a Cu pillar/Sn cap with 25-m pitch.…”

Section: Introductionmentioning

confidence: 99%

Effects of Cu orientation and stand-off-height on the microstructure of Cu/SnAgCu interface

Xiao

Liang

et al. 2014

2014 15th International Conference on Electronic Packaging Technology

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The effects of Cu orientation and stand-offheight on the microstructure and growth of IMCs in Cu/S nAgCu/Cu solder joints was investigated. Cu 6 Sn 5 and Cu 3 S n were the two key intermetallic compounds (IMCs) that formed at the interface. On (111) Cu substrate, prism-like Cu 6 Sn 5 grains could be observed after reflowing at 250 for 10s. On polycrystalline Cu substrate, only scallop-like Cu 6 Sn 5 grains formed and the grain size is smaller than that of (111) Cu. Then, samples were aged at 150 and the thickness of Cu 6 Sn 5 and Cu 3 Sn layers increased with the increasing aging time. We found that Cu 3 S n formed on (111) Cu substrate grew faster than that on polycrystalline Cu substrate , owing to Cu 3 S n columnar growth on (111) Cu and grain boundary diffusion control. After aging at 150 for 384 h, the IMC growing from the upper side and from the lower side touched each other in solder joints with 10 m SOH. Cu 6 Sn 5 stopped growing while Cu 3 Sn continued growing at the consumption of Cu 6 Sn 5 , resulting in the decrease of thickness of Cu 6 Sn 5 .

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Current density dependent shear performance and fracture behavior of micro-scale BGA structure Cu/Sn–3.0Ag–0.5Cu/Cu joints under coupled electromechanical loads

Ning

et al. 2019

J Mater Sci: Mater Electron

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Analysis of bump resistance and current distribution of ultra-fine-pitch microbumps

Cited by 13 publications

References 14 publications

A new failure mechanism of electromigration by surface diffusion of Sn on Ni and Cu metallization in microbumps

A new failure mechanism of electromigration by surface diffusion of Sn on Ni and Cu metallization in microbumps

Effects of Cu orientation and stand-off-height on the microstructure of Cu/SnAgCu interface

Current density dependent shear performance and fracture behavior of micro-scale BGA structure Cu/Sn–3.0Ag–0.5Cu/Cu joints under coupled electromechanical loads

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