Effect of contact metallization on electromigration reliability of Pb-free solder joints

Ding, Min; Wang, Guotao; Chao, Brook; Ho, Paul S.; Su, Peng; Uehling, Trent

doi:10.1063/1.2193037

Cited by 79 publications

(36 citation statements)

References 8 publications

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“…This is due to the fact that diffusivity of Cu is greater than that of Sn. A similar result was observed by Ding et al (2005Ding et al ( , 2006 under electromigration at 150°C isothermal temperature. They conclude that Cu atoms from Cu-UBM and Cu 6 Sn 5 dissolutions drift to bulk solder under electromigration driving force.…”

Section: Discussionsupporting

confidence: 78%

Thermomigration in lead-free solder joints

Abdulhamid

Basaran

2008

IJMSI

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Abstract:In the next generation nanoelectronics and SiC based electronic packaging, current density and temperature gradient will be larger in orders of magnitude. Electromigration and thermomigration are considered to be major road blocks leading to realisation of nanoelectronics and SiC based high temperature power electronics. In this paper, damage mechanics of 95.5Sn4Ag0.5Cu (SAC405) lead-free solder joints under high temperature gradients have been studied. This paper presents observations on samples which were subjected to 1000°C/cm thermal gradient for two hours, 286 hours, 712 hours and 1156 hours. It was observed that samples subjected to thermal gradient did not develop a Cu 3 Sn intermetallic compound (IMC) layer at the hot side due to Cu migration to the cold side thus causing insufficient Cu mass concentration to form Cu 3 Sn. On the other hand, in samples subjected to isothermal annealing exhibited IMC growth. In samples subjected to thermomigration, near the cold side the Cu concentration is significantly higher, compared to hot side. Extensive surface hardness testing showed increase in hardness from the hot to cold sides, which indicates vacancy migration and Sn grain coarsening are in the opposing direction.

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Section: Discussionsupporting

confidence: 78%

Thermomigration in lead-free solder joints

Abdulhamid

Basaran

2008

IJMSI

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“…Moreover, it has been demonstrated that electromigration has a remarkable effect on the initiation and propagation of Kirkendall voids. 1,2 Therefore, Kirkendall voids have emerged as a serious reliability threat for solder joint, and this research topic has been developed into a critical area of interest. It has been reported previously that extensive Kirkendall voids are generated at the solder/Cu interface and deteriorate the reliability of the solder joint under impact or shock loads.…”

Section: Introductionmentioning

confidence: 99%

Additive Effect of Kirkendall Void Formation in Sn-3.5Ag Solder Joints on Common Substrates

Gao

Nishikawa

Takemoto

2007

Journal of Elec Materi

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The Sn-3.5Ag and Sn-3.5Ag-0.2Co-0.1Ni lead-free solders were investigated on common electronics substrates, namely, organic solderability preservative (OSP) and electroless Ni/immersion Au (ENIG) surface finishes. The formation of Kirkendall voids at the interfacial region during isothermal solid aging was explored. For the Sn-3.5Ag-0.2Co-0.1Ni/OSP solder joint, the Kirkendall voids were present after isothermal solid-state aging at higher temperature (e.g., 150°C); however, the size of voids did not change remarkably with prolonged aging time due to the depressed Cu 3 Sn layer growth. For ENIG surface finishes, the 0.2Co-0.1Ni additions seemed to enhance the longitudinal grooveshaped voids at the Ni 3 P layer; however, void formation at the solder/Ni 3 Sn 4 interface was effectively reduced. This might be attributed to the reduced Sn activity in the solder matrix and the suppressed Ni-P-Sn layer formation.

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“…However they are defined, lifetimes for EM-induced failures of aluminum interconnects generally show very reasonable fits to lognormal statistics, [35][36][37][38] although the test structures used have a considerable effect on the details. As a general rule, bamboo and near bamboo Al structures with shunt layers tend to show growth dominated failure while, without the shunt layer, the nucleation time dominates the failure time.…”

Section: ͪ ͑1͒mentioning

confidence: 99%

Analysis of multistate models for electromigration failure

Dwyer

2010

Journal of Applied Physics

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Additional Information:• This article was published in the Journal of Applied Physics [ c Amer- The application of a multistate Markov chain is considered as a model of electromigration interconnect degradation and eventual failure. Such a model has already been used ͓Tan et al., J. Appl. Phys. 102, 103703 ͑2007͔͒, maintaining that, in general, it leads to a failure distribution described by a gamma mixture, and that as a result, this type of distribution ͑rather than a lognormal͒ should be used as a prior in any Bayesian mode fitting and subsequent reliability budgeting. Although it appears that the model is able to produce reasonably realistic resistance curves R͑t͒, we are unable to find any evidence that the failure distribution is a simple gamma mixture except under contrived conditions. The distributions generated are largely sums of exponentials ͑phase-type distributions͒, convolutions of gamma distributions with different scales, or roughly normal. We note also some inconsistencies in the derivation of the gamma mixture in the work cited above and conclude that, as it stands, the Markov chain model is probably unsuitable for electromigration modeling and a change from lognormal to gamma mixture distribution generally cannot be justified in this way. A hidden Markov model, which describes the interconnect behavior at time t rather than its resistance, in terms of generally observed physical processes such as void nucleating, slitlike growth ͑where the growth is slow and steady͒, transverse growth, current shunting ͑where the resistance jumps in value͒, etc., seems a more likely prospect, but treating failure in such a manner would still require significant justification.

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Effect of contact metallization on electromigration reliability of Pb-free solder joints

Cited by 79 publications

References 8 publications

Thermomigration in lead-free solder joints

Thermomigration in lead-free solder joints

Additive Effect of Kirkendall Void Formation in Sn-3.5Ag Solder Joints on Common Substrates

Analysis of multistate models for electromigration failure

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