The effect of electric current and surface oxidization on the growth of Sn whiskers

Kim, Kyung-Seob; Yang, Jun‐Mo; Ahn, Jae‐Pyoung

doi:10.1016/j.apsusc.2010.05.045

Cited by 24 publications

(9 citation statements)

References 17 publications

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“…Besides, the shape of the IML wedges can concentrate the stress [30]. Kim et al [31] reported similar results in the case of electroplated Sn layer with ~2 μm thickness, and Zhang et al [32] related the decreased whisker growth to the evenness IML layer, in the case of chemical Sn layer. Therefore, our hypothesis is that in the case of unpolished Cu substrate (S1), the IML wedges could exhibit stress peaks in some regions of the Sn layer, where very long filament whiskers [5,8] could grow.…”

Section: Discussionmentioning

confidence: 95%

Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

et al. 2019

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The effect of copper substrate roughness and tin layer thickness were investigated on whisker development in the case of Sn thin-films. Sn was vacuum-evaporated onto both unpolished and mechanically polished Cu substrates with 1 µm and 2 μm average layer thicknesses. The samples were stored in room conditions for 60 days. The considerable stress—developed by the rapid intermetallic layer formation—resulted in intensive whisker formation, even in some days after the layer deposition. The developed whiskers and the layer structure underneath them were investigated with both scanning electron microscopy and ion microscopy. The Sn thin-film deposited onto unpolished Cu substrate produced less but longer whiskers than that deposited onto polished Cu substrate. This phenomenon might be explained by the dependence of IML formation on the surface roughness of substrates. The formation of IML wedges is more likely on rougher Cu substrates than on polished ones. Furthermore, it was found that with the decrease of layer thickness, the development of nodule type whiskers increases due to the easier diffusion of other atoms into the whisker bodies.

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Section: Discussionmentioning

confidence: 95%

Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

et al. 2019

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“…Figure 7(a and b) show Cu-Sn pillars with a diameter of 40 m and pitch of 200 m. However, the surface morphologies of the Cu-Sn pillars in Figure 7(c and d) reveal a significantly different morphology of Sn compared to the reports in the references (Boettinger et al, 2005;Sahaym et al, 2010;Kim et al, 2010). It consisted of similar clusters, which were formed by an ordered arrangement of tetragonal Sn grains.…”

Section: Cu-sn Pillarsmentioning

confidence: 85%

Fabrication and characterization of Cu-Sn-Ni-Cu interconnection microstructure for electromigration studies in 3D integration

Xiao

Munief

et al. 2016

SSMT

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2016),"Thermo-mechanical challenges of reflowed lead-free solder joints in surface mount components: a review", Soldering & Surface Mount Technology, Vol. 28 Iss 2 pp. 41-62 http://dx.If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to fabricate a new Cu-Sn-Ni-Cu interconnection microstructure for electromigration studies in 3D integration. Design/methodology/approach -The Cu-Sn-Ni-Cu interconnection microstructure is fabricated by a three-mask photolithography process with different electroplating processes. This microstructure consists of pads and conductive lines as the bottom layer, Cu-Sn-Ni-Cu pillars with the diameter of 10-40 m as the middle layer and Cu conductive lines as the top layer. A lift-off process is adopted for the bottom layer. The Cu-Sn-Ni-Cu pillars are fabricated by photolithography with sequential electroplating processes. To fabricate the top layer, a sputtered Cu layer is introduced to prevent the middle-layer photoresist from being developed. With the final Cu electroplating processes, the Cu-Sn-Ni-Cu interconnection microstructure is successfully achieved. Findings -The surface morphology of Cu-Sn pillars consists of densely packed clusters which are formed by an ordered arrangement of tetragonal Sn grains. The diffusion of Cu atoms into the Sn phases is observed at the Cu/Sn interface. Furthermore, the obtained Cu-Sn-Ni-Cu pillars have a flat surface with an average roughness of 13.9 nm. In addition, the introduction of Ni layer between the Sn and the top Cu layers in the Cu-Sn-Ni-Cu pillars can mitigate the diffusion of Cu atoms into Sn phases. The process is verified by checking the electrical performance using four-point probe measurements. Originality/value -The method described in this paper which combined a three-mask photolithography process with sequential Cu, Sn, Ni and Cu electroplating processes provides a new way to fabricate the interconnection microstructure for future electromigration studies.

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“…However, these studies usually tried to find only the correlation between the roughness of the IMC layer and the propensity of whisker growth [37,38]. Basically, it is accepted that an uneven IMC layer can generate higher mechanical stress and more Sn whiskers than a uniform one [38,39] due to the larger active surface of the IMC layer. Compared to 2-μm-thick Sn film-layers-where almost only filament-type whiskers were found [40]-, the amount of the non-filament-type whiskers (mainly the hillocks) were very high in the present study (over 90% from the total amount of whiskers).…”

Section: Discussionmentioning

confidence: 99%

Kinetics of Sn whisker growth from Sn thin-films on Cu substrate

Illés

Krammer

Hurtony

et al. 2020

J Mater Sci: Mater Electron

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The kinetics of Sn whisker growth was investigated on vacuum-evaporated Sn thin-films. Sn film layers were deposited on a Cu substrate with 0.5 and 1 µm thicknesses. The samples were stored in room conditions (22 ± 1 °C/50 ± 5RH%) for 60 days. The Sn whiskers and the Cu–Sn layer structure underneath them were investigated with both scanning electron and ion microscopy. Fast Cu–Sn intermetallic formation resulted in considerable mechanical stress in the Sn layer, which initiated intensive whisker growth right after the layer deposition. The thinner Sn layer produced twice many whiskers compared to the thicker one. The lengths of the filament-type whiskers were similar, but the growth characteristics differed. The thinner Sn layer performed the highest whisker growth rates during the first 7 days, while the thicker Sn layer increased the growth rate only after 7 days. This phenomenon was explained by the cross-correlation of the stress relaxation ability of Sn layers and the amount of Sn atoms for whisker growth. The very high filament whisker growth rates might be caused by the interface flow mechanism, which could be initiated by the intermetallic layer growth itself. Furthermore, a correlation was found between the type of the whiskers and the morphology of the intermetallic layer underneath.

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The effect of electric current and surface oxidization on the growth of Sn whiskers

Cited by 24 publications

References 17 publications

Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

Fabrication and characterization of Cu-Sn-Ni-Cu interconnection microstructure for electromigration studies in 3D integration

Kinetics of Sn whisker growth from Sn thin-films on Cu substrate

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