Electromigration study of micro bumps at Si/Si interface in 3DIC package for 28nm technology and beyond

Lin, Ting-Huang; Wang, R. D.; Chen, M. F.; Chiu, Catherine; Chen, S. Y.; Yeh, Ta‐Chuan; Lin, Larry; Hou, S. Y.; Lin, Jiunn-Yuan; Chen, K. H.; Jeng, Shin-Puu; Yu, Douglas

doi:10.1109/ectc.2011.5898536

Cited by 14 publications

(9 citation statements)

References 7 publications

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“…A previous simulation work has shown that the maximum current density inside the bump is concentrated at the bump center [2]. Current distribution combined with grain orientation could explain why the residual Sn is more likely to exist at the peripheral of the bumps, as shown in Fig 17(c).…”

Section: (I) Em Behavior Of Full Imc Bumpsmentioning

confidence: 90%

“…When the scaling of semiconductor process technology becomes more challenging, 3D integration is becoming increasingly attractive as it promises benefits in system performance, small form factor, heterogeneous integration while at significantly reduced system integration cost and power consumption [1][2][3]. Solder bump is one of the key enabling technologies for 3D integration where high I/O count devices and interposers are interconnected with hundreds of thousands of bumps.…”

Section: Introductionmentioning

confidence: 99%

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Generic rules to achieve bump electromigration immortality for 3D IC integration

Chen

Shih

Cai

et al. 2013

2013 IEEE 63rd Electronic Components and Technology Conference

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An immortal solder micro-bump (bump) electromigration (EM) lifetime has been demonstrated for 3D IC integration. This ultimate goal was achieved under strictly controlled conditions, including the optimal design of bump metallurgy, geometry, optimized processes, along with welldefined stressing conditions and manufacturing window. The current carrying capability and EM lifetime of bump have been investigated as functions of stressing conditions which are correlated with the degradation mechanisms. When stressed under the appropriate g conditions, all bump test samples survived prolonged stressing, some over 13,000 hours, without a failure. Cross-sectional analyses revealed that the entire solder joint almost all transformed into intermetallic compounds (IMCs) with very minor or no voids. The resistance plots showed an initial fast rise in resistance due to IMC formation, then gradually leveled off and eventually reached a steady state. The observed degradation mechanism is dominated by IMC formation, which is the same as that of the user conditions. On the other hand, void formation that eventually led to open failure was the dominant degradation mechanism when samples were aggressively stressed. In other words, when all other conditions were the same, the stressing conditions make a huge difference in determining between an almost immortal EM lifetime vs. a short lifetime using the same high quality bumps. The boundary that separates the stressing conditions is roughly defined and will be discussed.In addition, since full IMC bump will become inevitable in the future miniaturized solder interconnect structure, the EM behavior of IMC dominated bump has also been evaluated in this study. Under highly accelerated stressing conditions of 174°C, at 1.6×10 5 A/cm 2 current density, the IMC dominated bumps were able to survive more than 600 hours and are still going strong. In comparison, solder bump failed quickly after just 107 hours when stressed under the same condition. This comparison study clearly demonstrated that IMC dominated joint has significantly higher current carrying capability than that of the solder joint. After reviewing all the data, we have concluded that the failure criteria for solder bump should be raised significantly higher than the 20% criteria traditionally used for the much larger C4 bumps.

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Section: (I) Em Behavior Of Full Imc Bumpsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Generic rules to achieve bump electromigration immortality for 3D IC integration

Chen

Shih

Cai

et al. 2013

2013 IEEE 63rd Electronic Components and Technology Conference

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“…The microvoid can be occurred at this connected location (Figure 4b). The resistances of the test samples were measured by in-situ to investigate the situation of the micro-bump degradation [15]. Figure 5 is the curves of the resistance increase ratio as a function of electromigration testing time for 150℃ at 1.5x 10 5 A/cm 2 .…”

Section: Methodsmentioning

confidence: 99%

Structure effects on the electrical reliability of fine-pitch Cu micro-bumps for 3D integration

Lee

Kim

et al. 2014

2014 IEEE 64th Electronic Components and Technology Conference (ECTC)

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Recently, flip chip solder bumps have been replaced by the fine-pitch solder micro-bump due to the miniaturization of electronic devices and the high performance requirement, and so on. Because of the fast decreasing size of the micro-bump and increasing power consumption needs in logic through-Si via applications, the significance of electromigration among major reliability issues have been increased. There are several important electrical current-induced reliability issues such as current crowding, polarity effect and thermomigration. And the excessive intermetallic compound (IMC) growth and Kirkendall voiding or micro voiding in micro-bump can degrade the mechanical reliability as well as electrical reliability. Therefore, the understanding of fundamental IMC growth mechanism is essential. This study systematically investigated the effects of bump structures such as solder height and UBM structure on the IMC growth kinetics and electromigration performance of Cu micro-bump. Quantitative analyses on the IMC growth kinetics during in-situ electromigration test were performed in a scanning electron microscope chamber under current stressing conditions with current density of 1.5 x 10 5 A/cm 2 at 150℃. Under high temperature and electric current stressing, the IMCs growth is accelerated by electron wind force. And the IMC phase transition time became shorter because IMC growth rates increased. In Cu/Sn-Ag and Cu/Ni/Sn-Ag system, the effect of current crowding and Joule heating was negligible in fully IMC-transformed micro-bump. Finally, microvoid formation mechanisms during IMC growth in the Cu/Ni/thin Sn system were discussed in detail.

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“…26 However, for electromigration in microbumps with solder thickness less than 20 lm under high current densities, the resistance curve behaves completely different. [27][28][29][30] The resistance increases abruptly in the beginning, followed by more gradual increase, thus causing the resistance curve to behave concave-down. Wei et al conducted electromigration tests in microbumps by 9.6 Â 10 4 A/cm 2 at 168 C and they observed concave-down resistance curves.…”

Section: Introductionmentioning

confidence: 99%

Experimental and simulation analysis of concave-down resistance curve during electromigration in solder joints

Lin

Chang

Chen

2014

Journal of Applied Physics

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Resistance curves play a crucial role in detecting damage of solder joints during electromigration. In general, resistance increases slowly in the beginning, and then rises abruptly in the very late stage; i.e., the resistance curve behaves concave-up. However, several recent studies have reported concave-down resistance curves in solder joints with no satisfactory explanation for the discrepancy. In this study, electromigration failure mode in Sn2.5Ag solder joints was experimentally investigated. The bump resistance curve exhibited concave-down behavior due to formation of intermetallic compounds (IMCs). In contrast, the curve was concave-up when void formation dominated the failure mechanism. Finite element simulation was carried out to simulate resistance curves due to formation of IMCs and voids, respectively. The simulation results indicate that the main reason causing the concave-down curve is rapid formation of resistive Cu 6 Sn 5 IMCs in the current-crowding region, which are 9 times larger than Cu IMCs. Therefore, when Cu reacted with Sn to form Cu 6 Sn 5 IMCs, resistance increased abruptly, resulting in the concave-down resistance curve. V

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Electromigration study of micro bumps at Si/Si interface in 3DIC package for 28nm technology and beyond

Cited by 14 publications

References 7 publications

Generic rules to achieve bump electromigration immortality for 3D IC integration

Generic rules to achieve bump electromigration immortality for 3D IC integration

Structure effects on the electrical reliability of fine-pitch Cu micro-bumps for 3D integration

Experimental and simulation analysis of concave-down resistance curve during electromigration in solder joints

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