Effect of Sn grain structure on electromigration reliability of Pb-free solders

Wang, Yiwei; Lu, Kaijun; Gupta, Vikas; Stiborek, Leon; Shirley, Dwayne R.; Im, Jungho; Ho, Paul S.

doi:10.1109/ectc.2011.5898591

Cited by 6 publications

(4 citation statements)

References 9 publications

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“…This was attributed to the full conversion of the µ-bumps into IMCs after assembly or under thermal annealing. The EM performance of IMC bumps was better than Sn-based solder joints [12]. EM did not enhance IMC growth significantly in the three types of structures investigated in this study.…”

Section: Discussionmentioning

confidence: 95%

“…With the joint size significantly smaller than the C4 solder joints and the need to increase the current density, electromigration (EM) has emerged as a critical reliability concern and has drawn considerable interests [6][7][8][9][10]. In Sn-based C4 solder joints, IMC formation resulting from material reactions between Sn and the under-bump metallurgy (UBM) was found to be enhanced under EM and played an important role in controlling the solder reliability [11,12]. For 3D chip stacking interconnection, the solder volume is substantially reduced because of package miniaturization and fine-pitch requirements.…”

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confidence: 99%

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Effect of intermetallic formation on electromigration reliability of TSV-microbump joints in 3D interconnect

Wang

Chae

Dunne

et al. 2012

2012 IEEE 62nd Electronic Components and Technology Conference

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In this study, electromigration (EM) reliability of TSVmicrobump (µ-bump) joints was investigated. Sn-based µ-bumps with three different schemes of metallization were tested under current stressing at elevated temperatures. EMstressed µ-bumps, together with thermal anneal-only µ-bumps and as-received controls, were cross-sectioned and characterized using scanning electron microscope (SEM), energy dispersed x-ray (EDX) and focused ion beam (FIB). Intermetallic compound (IMC) growth kinetics under EM for the three types of metallization were obtained, and compared with those subjected to thermal annealing only. Results showed good EM performance of the TSV µ-bump joints, indicating that IMC formation plays an important role in improving the EM reliability of µ-bump joints. However, non-EM related voids were observed in the µ-bumps, and the voiding mechanisms were discussed. IntroductionMicro-bumping is one of the key technologies in 3D integration [1]. This technology, together with through-sliconvias (TSVs), forms electrical connections between stacked dies in a 3D integrated circuits. As the I/O counts increase and the pitch size decreases, material selection for the bonding metallurgy and reliability of the fine-pitch interconnect joining have become critical issues in 3D chip stacking. Finepitch silicon-to-silicon stacking approaches include transient liquid phase (TLP) bonding resulting in intermetallic compound (IMC) after joining [2], metal to metal (Cu-Cu) bonding by thermal compression [3], and micro-controlled collapse chip connection (µ-C4) or µ-bumps through mass reflow or thermal compression [4,5].Sn-based µ-bumps are currently used by the microelectronic industry due to its process compatibility with the current assembly technologies. With the joint size significantly smaller than the C4 solder joints and the need to increase the current density, electromigration (EM) has emerged as a critical reliability concern and has drawn considerable interests [6][7][8][9][10]. In Sn-based C4 solder joints, IMC formation resulting from material reactions between Sn and the under-bump metallurgy (UBM) was found to be enhanced under EM and played an important role in controlling the solder reliability [11,12]. For 3D chip stacking interconnection, the solder volume is substantially reduced because of package miniaturization and fine-pitch requirements. The limited supply of Sn induces more extensive IMC formation and can convert the entire bump into IMC upon thermal annealing or under current stressing. The extensive IMC growth in Sn-based µ-bumps gives rise to EM

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Section: Discussionmentioning

confidence: 95%

mentioning

confidence: 99%

Effect of intermetallic formation on electromigration reliability of TSV-microbump joints in 3D interconnect

Wang

Chae

Dunne

et al. 2012

2012 IEEE 62nd Electronic Components and Technology Conference

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“…Therefore, the effect of the Sn grain orientation on EM failure in Sn solder joints with Ni UBMs under a current density of 7.7 × 10 3 A/cm 2 was first observed by Lu et al [ 49 ]. Since then, substantial studies on this effect have been reported [ 50 , 51 , 52 , 53 , 54 , 55 ]. In the studies, the extra-fast UBM dissolution of Cu/Ni at the cathode occurs as the electron flow is closely parallel to the c-axis, which possesses a high diffusion rate.…”

Section: Effect Of Sn Grain Orientation On Electromigrationmentioning

confidence: 99%

Effect of Sn Grain Orientation on Reliability Issues of Sn-Rich Solder Joints

Shen

2022

Materials

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Sn-rich solder joints in three-dimensional integrated circuits and their reliability issues, such as the electromigration (EM), thermomigration (TM), and thermomechanical fatigue (TMF), have drawn attention related to their use in electronic packaging. The Sn grain orientation is recognized as playing an important role in reliability issues due to its anisotropic diffusivity, mechanical properties, and coefficient of thermal expansion. This study reviews the effects of the Sn grain orientation on the EM, TM, and TMF in Sn-rich solder joints. The findings indicate that in spite of the failure modes dominated by the Sn grain orientation, the size and shape of the solder joint, as well as the Sn microstructures, such as the cycling twining boundary (CTB), single crystals, and misorientations of the Sn grain boundary, should be considered in more detail. In addition, we show that two methods, involving a strong magnetic field and seed crystal layers, can control the Sn grain orientations during the solidification of Sn-rich solder joints.

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“…The additive blocks the association of generated hydrogen atoms according to Equation (14). Consequently, the concentrations of H ads rises following Equation (15). The combined effect of these two phenomena (Equations 15 and 16) results in absorption of hydrogen atoms in the deposits according to Equation (16).…”

Section: Additivesmentioning

confidence: 99%

Pulse Electroplating of Ultrafine Grained Tin Coating

Sharma¹,

Das²,

Das³

2015

Electroplating of Nanostructures

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In the electronic packaging industries, soldering materials are essential in joining various microelectronic networks. Solders assure the reliability of joints and protect the microelectronic packaging devices. They provide electrical, thermal, and mechanical continuity among various interconnections in an electronic device. The service performance of all the electronic appliances depends on high strength and durable soldering materials. Lead-containing solders are in use for years, resulting in an extensive database for the reliability of these materials. However, due to toxicity and legislations, lead-free solders are now being developed. As tin (Sn) is the major component of solders, this chapter presents the detailed results and discussion about the metallurgical overview of Sn, synthesis, and characterization of pulse electrodeposited pure tin finish from different aqueous solution baths. The experiments on pulse electrodeposition such as common tin plating baths employed, their chemical compositions, rationale behind their selection and their characterization by bath conductivity and cathodic current efficiency, microstructures, and tin whisker growth are discussed. Further, the effect of pulse electrodeposition parameters such as current density, additive concentration, pH, duty cycle, frequency, temperature, and stirring speed on microstructural characteristics of the coating obtained from sulfate bath and their effect on grain size distribution have been presented.

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Effect of Sn grain structure on electromigration reliability of Pb-free solders

Cited by 6 publications

References 9 publications

Effect of intermetallic formation on electromigration reliability of TSV-microbump joints in 3D interconnect

Effect of intermetallic formation on electromigration reliability of TSV-microbump joints in 3D interconnect

Effect of Sn Grain Orientation on Reliability Issues of Sn-Rich Solder Joints

Pulse Electroplating of Ultrafine Grained Tin Coating

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