Effect of under-bump-metallization structure on electromigration of Sn-Ag solder joints

Chen, Hsiao-Yun; Ku, Min-Feng; Chen, Chih

doi:10.12989/amr.2012.1.1.083

Cited by 26 publications

(15 citation statements)

References 23 publications

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“…This phenomenon was barely found in the electromigration tests when solder was not consumed completely. [8][9][10][11] The mechanism of forming porous Cu 3 Sn was due to the phase transformation: Cu 6 Sn 5 →2 Cu 3 Sn+3 Sn. In the Sn-lack system, the Cu 6 Sn 5 would transform into Cu 3 Sn and released the Sn atoms.…”

Section: Resultsmentioning

confidence: 99%

Electromigration in microbumps with Cu-Sn intermetallic compounds

Chu

Zhan

Lin

et al. 2016

2016 International Conference on Electronics Packaging (ICEP)

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The electromigration test of the microbump interconnects with Cu/Cu6Sn5/Cu structure is reported in this study. This Cu6Sn5 intermetallic compound layer was singlecrystal like. The diameter of the microbumps in die-to-die stacking was 30 μm. Test vehicles were applied by a current density of 2.2x10 5 A/cm 2 and settled on a hotplate at 150 o C. The resistances of the microbumps were simultaneously monitored by the four point probe during the test procedure. The Cu6Sn5 transformed into Cu3Sn in the early stage and porous Cu3Sn generated in the Cu6Sn5 layer at later stages. The morphology of porous Cu3Sn could be caused by the current direction. The decomposition of Cu6Sn5 into Cu3Sn and Sn occurs during the EM test. The migration of Sn atoms to the periphery of the underbump-metallization was forced by the current stress, which may be the mechanism of the pore formation with the pore volume of 41.4%. More porous Cu3Sn was found in the cathode end which was an evidence of the EM effect. Finite element analysis was used to do some calculation based on theoretical stoichiometry and microstructures in the test results. The resistivity of porous Cu3Sn structure which was about 30 μΩ−cm which was three times larger than that of Cu3Sn. The porous Cu3Sn may threaten the reliability issues of microbumps.

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Section: Resultsmentioning

confidence: 99%

Electromigration in microbumps with Cu-Sn intermetallic compounds

Chu

Zhan

Lin

et al. 2016

2016 International Conference on Electronics Packaging (ICEP)

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“…The bump resistance increases due to void formation and microstructure changes during EM can be precisely measured with Kelvin bump probes [1]. IMCs such as Cu 6 Sn 5 and Ni 3 Sn 4 have a higher resistivity than pure Sn.…”

Section: B Intermetallic Compound Resistivitymentioning

confidence: 99%

“…During the first phase practically no resistance increase can be measured. The situation is quite different in the case of EM failure development in a Sn bump, where an IMC-layer is also present [1]. From the beginning of EM-stressing a continuous growth of the bump resistance (c.f.…”

Section: Introductionmentioning

confidence: 99%

“…After a certain period of EM stressing [1], the bump resistance starts to rise with a significantly steeper slope. Chen et al [1] assume that the two slopes of the resistance growth may represent two different stages of failure development: void nucleation combined with IMC growth and void propagation with IMC dissolution. Investigation of physical mechanisms behind such a failure behavior is the main subject of this work.…”

Section: Introductionmentioning

confidence: 99%

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Impact of intermetallic compound on solder bump electromigration reliability

Ceric

Singulani

Orio

et al. 2013

2013 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)

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Solder bumps are important interconnect components for 3D integration. Their mechanical and electrical properties influence the overall reliability of 3D ICs. A characteristic of solder bumps is that during technology processing and usage their material composition changes. This compositional transformation influences the operation of 3D ICs and, in connection with electromigration, may cause failures in ICs. In this paper we present a model for describing the growth of intermetallic compound inside a solder bump under the influence of electromigration. Simulation results based on the new model are discussed in conjunction with corresponding experimental findings.

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“…In the literature, the majorities of studies are focusing on electromigration test and solder diameter larger than 80 μm [3,4,5]. C. Chen et al reported the solder joints with Cu/Ni UBM have lower maximum current density and hot-spot temperature in solder, which contribute to the longer electromigration lifetime [3].…”

Section: Introductionmentioning

confidence: 99%

Thermal cycling effect on intermetallic formation with various surface finish of micro bump interconnect for 3D package

Chan

Liao

Lin

et al. 2013

2013 IEEE 63rd Electronic Components and Technology Conference

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Micro bump interconnect with through-silicon via (TSV) is one of the critical issues for realizing three dimensional (3D) packages. This enabling technology provides more I/O in shrunken die area, and hence high density interconnection. Electroless Ni immersion Au (ENIG), electroless Ni electroless Pd immersion Au (ENEPIG), and plating Tin are commonly used surface finish for Cu pad in lead-free package. However, the majority of studies are focusing on Controlled Collapse Chip Connection (C4) solder. Intermetallic compounds (IMC) formation is a result of interaction between the solder tip, barrier layer, Cu pillar form the top die and micro pad finish from the interposer. As a result, microstructure made with different pad finish will major impact to solder reliability.In this study, three types of pad finish including ENIG, ENEPIG, and plating Tin were chosen to evaluate intermetallic formation during thermal cycling test. In addition, presence of Ni was also discussed to understand IMC formation in this microstructure. Multi reflow (at time zero, 1x, 3x) and thermal cycling test were performed for this evaluation. Metallurgy and growth kinetics of IMC were compared at different thermal cycling. The results show that SnAg bump with ENEPIG pad finish have more Cu consumption than ENIG after pre-con. ENEPIG pad finish exhibits crack formed between (Ni,Cu) 6 Sn 5 and P-rich layer. The detailed influence of Ni with various pad finish on the growth kinetics of IMC formation was investigated and discussed.

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Effect of under-bump-metallization structure on electromigration of Sn-Ag solder joints

Cited by 26 publications

References 23 publications

Electromigration in microbumps with Cu-Sn intermetallic compounds

Electromigration in microbumps with Cu-Sn intermetallic compounds

Impact of intermetallic compound on solder bump electromigration reliability

Thermal cycling effect on intermetallic formation with various surface finish of micro bump interconnect for 3D package

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