Interface reaction systematics in the Cu/In–48Sn/Cu system bonded by diffusion soldering

Sommadossi, S.; Guillermet, A. Fernández

doi:10.1016/j.intermet.2006.10.050

Cited by 52 publications

(32 citation statements)

References 17 publications

(12 reference statements)

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“…With a highmelting seal, not only can the sealed packages be engaged in subsequent soldering steps, but also joint creep resistance and dimensional stability can be improved. Many studies have been carried out on the characterization of the interfacial reaction between a Cu substrate and bulk In-Sn alloy, 3,[10][11][12][13][14][15] where the eutectic solder In-48wt.%Sn is applied on the substrate either by dipping into a molten solder bath 3,10-12 or sandwiching a solder foil. [10][11][12] However, the reaction between Cu and bulk solder should be different from the thin-film case because in the latter case there is only a limited amount of solder material in contact with the substrate and the chemical composition in the solder layers is inhomogeneous.…”

Section: Introductionmentioning

confidence: 99%

A Hermetic Seal Using Composite Thin-Film In/Sn Solder as an Intermediate Layer and Its Interdiffusion Reaction with Cu

Yan

Lee

et al. 2008

Journal of Elec Materi

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A bonding joint between Cu metallization and evaporated In/Sn composite solder is produced at a temperature lower than 200°C in air. The effects of bonding temperature and duration on the interfacial bonding strength are studied herein. Cross sections of bonding joints processed at different bonding conditions were examined by scanning electron microscopy (SEM). The optimal condition, i.e., bonding temperature of 180°C for 20 min, was chosen because it gave rise to the highest average bonding strength of 6.5 MPa, and a uniform bonding interface with minimum voids or cracks. Good bond formation was also evidenced by scanning acoustic imaging. For bonding couples of patterned dies, a helium leak rate of 5.8 9 10 -9 atm cc/s was measured, indicating a hermetic seal. The interfacial reaction between Cu and In/Sn was also studied. Intermetallic compounds (IMCs) such as AuIn 2 , Cu 6 Sn 5 , and Cu 11 In 9 were detected by means of x-ray diffraction analysis (XRD), and transmission electron microscopy (TEM) accompanied by energy-dispersive x-ray (EDX) spectroscopy. Chemical composition analysis also revealed that solder interlayers, Sn, and In were completely converted into IMCs by reaction with Cu. All the IMCs formed in the joints have remelting temperatures above 300°C according to the Cu-In, Cu-Sn, and Au-In phase diagrams. Therefore, the joint is able to sustain high service temperatures due to the presence of these IMCs.

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Section: Introductionmentioning

confidence: 99%

A Hermetic Seal Using Composite Thin-Film In/Sn Solder as an Intermediate Layer and Its Interdiffusion Reaction with Cu

Yan

Lee

et al. 2008

Journal of Elec Materi

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“…8, according to the thermodynamic calculation of phase equilibrium in a Cu-In-Sn system at 180 C [15], an phase existed in the system. It was known that phase existed in both the two binary systems Cu-In and Cu-Sn, i.e., -Cu In and -Cu Sn , with the same NiAs-type structure [16]. According to the study of Sommadossi et al and the high solubility of Sn, the compounds should be -Cu (Sn-In) [16].…”

Section: B Microstructure Of Seal Ring After Bondingmentioning

confidence: 99%

“…It was known that phase existed in both the two binary systems Cu-In and Cu-Sn, i.e., -Cu In and -Cu Sn , with the same NiAs-type structure [16]. According to the study of Sommadossi et al and the high solubility of Sn, the compounds should be -Cu (Sn-In) [16]. For , the compositions corresponded to Au(In-Sn) phases.…”

Section: B Microstructure Of Seal Ring After Bondingmentioning

confidence: 99%

Wafer-Level Hermetic Bonding Using Sn/In and Cu/Ti/Au Metallization

Yan

Lee

Choi

et al. 2009

IEEE Trans. Comp. Packag. Technol.

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Abstract-Low-temperature hermetic wafer bonding using In/Sn interlayer and Cu/Ti/Au metallization was investigated for microelectromechanical systems packaging application. In this case, the thin Ti layer was used as a buffer layer to prevent the diffusion between solder interlayer and Cu after deposition and to save more solders for diffusion bonding process. Bonding was performed in a wafer bonder at 180 and 150 C for 20 min with a pressure of 5.5 MPa. It was found that bonding at 180 C voids free seal joints composed of high-temperature intermetallic compounds were obtained with good hermeticity. However, with bonding at 150 C, voids were generated along the seal joint, which caused poor hermeticity compared with that bonded at 180 C. After four types of reliability tests-pressure cooker test, high humidity storage, high-temperature storage, and temperature cycling test-dies bonded at 180 C showed good reliability properties evidenced by hermeticity test and shear tests. Results presented here prove that high-yield and low-temperature hermetic bonding using Sn/In/Cu metallization with thin Ti buffer layer can be achieved.Index Terms-Hermeticity, In-Sn, microelectromechanical systems (MEMS), reliability, wafer bonding, wafer-level packaging.

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“…14 A similar problem has also been observed for Cu/SnIn bonding with Cu/Sn-In. 15 In this work, the properties of the bonded Cu/SnIn (at noneutectic compositions) interface were investigated. By using this structure, the issue of having a competing reaction at the interface of the Cu and underlying solder layer is eliminated.…”

Section: Introductionmentioning

confidence: 99%

Influence of Bonding Parameters on the Interaction Between Cu and Noneutectic Sn-In Solder Thin Films

Sasangka

Gan

Thompson

et al. 2011

Journal of Elec Materi

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Thermocompression bonding of through-layer copper interconnects is of great interest for fabrication of three-dimensional (3D) integrated circuits. We have investigated interactions of Cu films with noneutectic Sn-In at length scales of 1 lm to 5 lm. The effects of bonding time, bonding temperature, and postbonding annealing temperature on intermetallic compound (IMC) formation, joint microstructure, and shear strength were investigated using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), x-ray diffractometry (XRD), and shear testing. It is shown that bonding temperature plays an important role in increasing the true contact area, while the postbonding annealing temperature affects the formation of a single IMC, the g-phase [Cu 6 (Sn,In) 5 ]. Both of these phenomena were found to contribute to the shear strength of the joints. It is shown that two-step bonding processes, involving short bonding times and longer postbonding annealing, can be used to optimize the bond formation for increased throughput.

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Interface reaction systematics in the Cu/In–48Sn/Cu system bonded by diffusion soldering

Cited by 52 publications

References 17 publications

A Hermetic Seal Using Composite Thin-Film In/Sn Solder as an Intermediate Layer and Its Interdiffusion Reaction with Cu

A Hermetic Seal Using Composite Thin-Film In/Sn Solder as an Intermediate Layer and Its Interdiffusion Reaction with Cu

Wafer-Level Hermetic Bonding Using Sn/In and Cu/Ti/Au Metallization

Influence of Bonding Parameters on the Interaction Between Cu and Noneutectic Sn-In Solder Thin Films

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