Suppression of Void Formation at Sn/Cu Joint Due to Twin Formation in Cu Electrodeposit

Tsai, Shan-Ting; Chiang, Ping-Chen; Liu, Chang; Feng, Shien-Ping; Chen, Chih‐Ming

doi:10.1007/s11837-019-03576-8

Cited by 10 publications

(5 citation statements)

References 39 publications

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“…Recently, different Cu plating additives could change the microstructures of electroplated Cu. [15][16][17] Σ3 twinned Cu has several properties applied for electronic packaging, [18][19][20] such as great mechanical strength and thermal stability, [21][22][23] history-independent cyclic response, 24 and good resistance against electromigration. 25,26 One of these properties is to serve as a vacancy sink.…”

mentioning

confidence: 99%

Electrodeposition of Twinned Cu with Strong Texture Effect on Voiding Propensity in Electroplated Cu Solder Joints

Chiang

Shen

Feng

et al. 2020

J. Electrochem. Soc.

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Electrodeposition of Cu receives considerable attention due to its wide application in microelectronic products. Sn-rich alloys are commonly used to join the electroplated Cu to form solder joints, while their interactions give rise to undesired Kirkendall voids. Suppression of voids is imperative to ensure reliable solder joints with mechanical robustness. In this study, twinned Cu with various crystal orientations are constructed using electroplating and their efficacy on void suppression are investigated. Four Cu electroplated films (Cu A, B, C, and D) with numerous twin boundaries and different (111) and (110) ratios are joined with Sn-rich solder (SAC305) and thermally aged at 200 °C. The voiding propensity is in an order of Cu D > Cu C > Cu B > Cu A, inversely corresponding to their (111) ratios (Cu A > Cu B > Cu C > Cu D). Particularly, a void-free solder joint constructed by the electroplated Cu A film with plenty of twinned bamboo structures is observed. The findings demonstrate that Σ3 twin boundary in the bamboo structure with 〈111〉-preferred orientation has much higher efficiency at suppressing the Kirkendall effect than that in 〈110〉-preferred Cu films.

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mentioning

confidence: 99%

Electrodeposition of Twinned Cu with Strong Texture Effect on Voiding Propensity in Electroplated Cu Solder Joints

Chiang

Shen

Feng

et al. 2020

J. Electrochem. Soc.

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“…Notably, void formation at the solder–Cu joints may also be induced by the existence of impurities [ 91 , 92 ]. Additives in the electrolyte can introduce impurities in Cu films to form voids during thermal aging.…”

Section: Reliability Of Nt-cu In Electronic Packagingmentioning

confidence: 99%

“…Very few Kirkendall voids could be seen on the Cu 3 Sn-nt-Cu interface during solid-state aging at 150 • C for 500 h. The explanation for this phenomenon was that the high density of TBs in nt-Cu films could serve as vacancy sinks during the aging reaction and, thus, the number of Kirkendall voids declined. Chih-Ming Chen's group [89] Notably, void formation at the solder-Cu joints may also be induced by the existence of impurities [91,92]. Additives in the electrolyte can introduce impurities in Cu films to form voids during thermal aging.…”

Section: Interfacial Reaction Layersmentioning

confidence: 99%

Research Progress of Electroplated Nanotwinned Copper in Microelectronic Packaging

Chen

Gao

et al. 2023

Materials

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Copper is the most common interconnecting material in the field of microelectronic packaging, which is widely used in advanced electronic packaging technologies. However, with the trend of the miniaturization of electronic devices, the dimensions of interconnectors have decreased from hundreds of microns to tens of or even several microns, which has brought serious reliability issues. As a result, nanotwinned copper (nt-Cu) has been proposed as a potential candidate material and is being certified progressively. Firstly, the physical properties of nt-Cu have been widely studied. Notably, the higher thermal stability and oxidation resistance of the (111) texture causes nt-Cu to maintain excellent physical properties under high-temperature serving conditions. Secondly, recent works on the electrolyte and electroplating processes of nt-Cu on wafer substrates are summarized, focusing on how to reduce the thickness of the transition layer, improve the twin density, and achieve complicated pattern filling. Thirdly, nt-Cu can effectively eliminate Kirkendall voids when it serves as UBM or a CuP. Additionally, the high (111) texture can control the preferred orientation of interfacial intermetallic compounds (IMCs) at the Cu–Sn interface, which should be helpful to improve the reliability of solder joints. nt-Cu has superior electromigration resistance and antithermal cycling ability compared to ordinary copper RDLs and TSVs. Above all, nt-Cu has attracted much attention in the field of microelectronic packaging in recent years. The preparation–performance–reliability interrelationship of nt-Cu is summarized and displayed in this paper, which provides a solid theoretical basis for its practical applications.

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“…11,12 A highlevel incorporation of organics or impurities in Cu has been found to bring about serious structural damages to the solder joints constructed by Sn-based alloys and electroplated Cu. [13][14][15][16][17][18][19][20][21][22][23][24][25] The presence of the impure species annihilated the vacancy sinks like grain boundaries and dislocations, accelerating the oversaturation of vacancy concentration to form massive voids together with the growth of intermetallic compounds (IMCs) in the solder joints. 22 Precise control of the impurity concentration down to a threshold by formulating the additives was proven to be able to successfully suppress the void propagation.…”

mentioning

confidence: 99%

“…33,34 In other words, the driving force for the diffusion of Sn in (Cu,Ni) 6 Sn 5 was increased but that for the diffusion of Cu in Cu 3 Sn was reduced significantly. 35 The impurity effect on the void formation in the Sn-based solder/ Cu joints has been extensively studied [13][14][15][16][17][18][19][20][21][22][23][24][25] ; however, the Sn-based solders used for investigations were free of Ni. Because the addition of Ni in the Sn-based solders can influence the void formation in the solder joints, 27,[32][33][34][35] it is of high interests to investigate the impurity effect in the Ni-containing solder joints.…”

mentioning

confidence: 99%

Influences of Impurity Incorporation in Electroplated Cu on the SnAgCu and Ni-Containing SnAgCu Solder Joints

Chen¹,

Li²,

Yen³

et al. 2022

J. Electrochem. Soc.

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SnAgCu and Ni-containing SnAgCu alloys are Pb-free solders widely used to join with Cu to construct solder joints. Electrodeposition is a technology commonly used to fabricate Cu but co-deposition of organic impurities originating from additives is an inevitable reliability issue. This study investigates the impurity effect on the voiding propensity in the two solder joints (SnAgCu/Cu and SnAgCu-Ni/Cu) subjected to thermal aging at 200°C. Results show that a high level of impurity incorporation causes massive void propagation along the SnAgCu/Cu and SnAgCu-Ni/Cu interface. Reduction of the impurity concentration by precise control of the additive formulas can weaken the impurity effect and effectively suppress the void propagation. The weakening phenomenon of the impurity effect is more pronounced in the SnAgCu-Ni/Cu joint, indicating that suppression of the Cu3Sn growth as well as Kirkendall voids by Ni addition is also helpful in reducing the influences of impurities.

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Suppression of Void Formation at Sn/Cu Joint Due to Twin Formation in Cu Electrodeposit

Cited by 10 publications

References 39 publications

Electrodeposition of Twinned Cu with Strong Texture Effect on Voiding Propensity in Electroplated Cu Solder Joints

Electrodeposition of Twinned Cu with Strong Texture Effect on Voiding Propensity in Electroplated Cu Solder Joints

Research Progress of Electroplated Nanotwinned Copper in Microelectronic Packaging

Influences of Impurity Incorporation in Electroplated Cu on the SnAgCu and Ni-Containing SnAgCu Solder Joints

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