Electromigration-induced back stress in critical solder length for three-dimensional integrated circuits

Huang, Yi-Chung; Hsu, Hui-Yu; Wu, Albert T.

doi:10.1063/1.4861740

Cited by 14 publications

(6 citation statements)

References 29 publications

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“…Therefore, the supply of Cu increased the growth of the interfacial IMC at the anode. The stress gradient during electromigration is commonly known as "back stress" [30]. It was found that the anode underwent the highest compressive stress due to the accumulation of the atoms.…”

Section: Interfacial Intermetallic Compound (Imc) Under Electromigration and Thermal Ageingmentioning

confidence: 99%

Effect of Electromigration and Thermal Ageing on the Tin Whiskers’ Formation in Thin Sn–0.7Cu–0.05Ga Lead (Pb)-Free Solder Joints

et al. 2021

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The investigation on tin (Sn) whiskers formation has been widely applied in the field of lead-free electronic packaging. This is due to the fact that use of the Sn–Pb finishes has converted to Pb-free finishes in the electronic industry. Sn whiskers can grow long enough to cause a short circuit, which affects electronic devices’ reliability. This study investigates Sn whiskers’ formation in the thin Sn–0.7Cu–0.05Ga Pb-free solder under the influence of electromigration and thermal ageing for surface finish applications. The samples were stored in ambient conditions for 1000 h before being exposed to electromigration and thermal ageing to study the corresponding whiskers’ growth. A scanning electron microscope (SEM) was used to study the Sn whiskers’ microstructure, while an optical microscope (OM) was utilized to investigate the IMC layers in the samples. The results show that the addition of 0.05 wt.% gallium (Ga) decreased the Sn whisker’s length and growth density while simultaneously refining the IMC layers. Synchrotron micro-XRF (µ-XRF) shows the existence and distribution of Ga addition in both electromigration and thermal ageing samples. The shear test was used to determine the solder alloys’ mechanical properties. As a result, the addition of Ga to the Sn–0.7Cu solder improved the fracture morphology of solder joints. In conclusion, Ga’s addition resulted in decreasing Sn whisker formation and refining of the IMCs while also increasing the shear strength of the Sn–0.7Cu solder by ~14%.

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Section: Interfacial Intermetallic Compound (Imc) Under Electromigration and Thermal Ageingmentioning

confidence: 99%

Effect of Electromigration and Thermal Ageing on the Tin Whiskers’ Formation in Thin Sn–0.7Cu–0.05Ga Lead (Pb)-Free Solder Joints

et al. 2021

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“…The increased resistance, even a broken circuit caused by electromigration, could lead to severe reliability problems. While the technology has progressed significantly in recent years thanks to extensive developmental efforts, related studies have identified a few areas of concern that are critical challenges [ 5 , 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

The Study of the Reliability of Complex Components during the Electromigration Process

et al. 2023

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With the increasing number of inputs and outputs, and the decreasing interconnection spacing, electrical interconnection failures caused by electromigration (EM) have attracted more and more attention. The electromigration reliability and failure mechanism of complex components were studied in this paper. The failure mechanism and reliability of complex components during the electromigration process were studied through the simulation and the experiment, which can overcome the limitation of experimental measurement at a micro-scale. The simulation results indicated that the solder joint has obvious current crowding at the current inlet, which will significantly enhance the electromigration effect. Based on the atomic flux divergence method, the void formation of solder joints can be effectively predicted, and life prediction can be more accurate than Black’s equation. Experimental results indicated that the resistance of the daisy chain could be significantly increased with the process of void formation in the solder and corrosion of the leads. Moreover, the growth of intermetallic compounds can be obviously promoted under current stress. The main composition of the intermetallic compounds changes from almost entirely Cu5Sn6 to Cu5Sn6 and Cu3Sn; the cracks can be detected at the Cu3Sn layer. Specifically, the mean time to failure is 1065 h under 1.4 A current and 125 °C based on IPC-9701A guidelines.

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“…In their research on [ 34 ] Sn−Ag−Cu lead−free solder joints, Guo et al found that the diffusion rate of atoms, such as Cu and Ag, along the β−Sn grain, with a body−centered tetragonal structure (a = b = 0.583 nm, c = 0.318 nm) on the c−axis (<0.01> crystal phase), is much greater than that on the a− and b−axes, and the angle θ between the c−axis and the electron flow direction has a significant impact on the service life of micro−solder joints under electromigration. In their study on the relationship between electromigration damage and Sn grain orientation in Cu/Sn/Cu solder joints, Huang et al [ 35 ] found that the IMC tends to separate at the β−Sn boundary at the small angle between the c−axis of the β−Sn grains and the electron flow. The dissolution of the cathode IMC is also affected by β−Sn grain orientation control.…”

Section: Introductionmentioning

confidence: 99%

Study on Microstructure and Mechanical Properties at Constant Electromigration Temperature of Sn2.5Ag0.7Cu0.1RE0.05Ni-GNSs/Cu Solder Joints

Zhang

Gao

et al. 2023

Materials

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To solve the electromigration problem of micro−electronic connection solder joints, an ideal electromigration tester was designed, and the thickness of the intermetallic compounds (IMCs), average void diameter, grain orientation, failure, shear strength, and fracture path of Sn2.5Ag0.7Cu0.1RE0.05Ni−GNSs/Cu solder joints under constant−temperature electromigration were studied. The results indicate that the solder joints show evidence of typical electromigration polarity in the asymmetric growth of interfacial IMCs on the anode and cathode sides under the conditions of a current density ≥7 × 103 A/cm2 and an included angle between the c−axis of the β−Sn grains and the current direction θ ≤ 53.2°. The anode−side interfacial IMC is dominated by a Cu6Sn5 phase with a gradually increasing thickness, forming a Cu3Sn phase and showing evidence of microcracks. The Cu6Sn5 phase of the cathode−side interfacial IMC is gradually completely dissolved, and the growth of the Cu3Sn phase is accompanied by the formation of Kirkendall voids. The anisotropic diffusion of Cu atoms in the β−Sn of the micro−solder joints causes increased solder joint resistance and reduced shear strength. The shear fracture path of the solder joints moves from the cathode side near the IMC solder seam to the Cu3Sn interface. The shear fracture mechanism changes from ductile transgranular fracture dominated by β−Sn dimples to brittle fracture dominated by interfacial IMC cleavage and slip steps.

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Electromigration-induced back stress in critical solder length for three-dimensional integrated circuits

Cited by 14 publications

References 29 publications

Effect of Electromigration and Thermal Ageing on the Tin Whiskers’ Formation in Thin Sn–0.7Cu–0.05Ga Lead (Pb)-Free Solder Joints

Effect of Electromigration and Thermal Ageing on the Tin Whiskers’ Formation in Thin Sn–0.7Cu–0.05Ga Lead (Pb)-Free Solder Joints

The Study of the Reliability of Complex Components during the Electromigration Process

Study on Microstructure and Mechanical Properties at Constant Electromigration Temperature of Sn2.5Ag0.7Cu0.1RE0.05Ni-GNSs/Cu Solder Joints

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