Low-temperature all-Cu interconnections formed by pressure-less sintering of Cu-pillars with nanoporous-Cu caps

Sosa, Ramon A.; Mohan, Kashyap; Αντωνίου, Αντωνία; Smet, Vanessa; Thienpont, Denise; Tan, Y.Y.

doi:10.1109/ectc32696.2021.00072

Cited by 9 publications

(2 citation statements)

References 13 publications

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“…In order to adapt this process to flip-chip interconnects such as nanofoam on top of Cu-pillars. [14][15] However, the elaboration of the nanofoam would increase cost, time and complexity of fabrication, whereas a significant bonding pressure (100 MPa) has to be applied to form interconnects. Also, electrically bond has not yet be demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Development and Characterizations of Fine Pitch Flip-Chip Interconnection Using Silver Sintering

Gougeon,

Souriau,

Mendizabal

et al. 2024

IMAPSource Proceedings

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Flip-chip interconnects made of silver are promising candidates to overcome the intrinsic limits of solderbased interconnects and match the demand for increased current densities of high-performance microprocessors. Dipbased interconnects have been demonstrated to be a promising approach to form electrical interconnects by sintering paste between copper pillars and pads. However, the quality of the process is limited by residual porosity and poor performances of the sintered joint formed between the pillar and the pad during sintering if a pressure > 50 MPa is not applied in order to decrease the final porosity. In this study, development has been focused on varying key dipping process parameters allowing a pressureless sintering process. Dip-transfer process was optimized on test vehicle and has shown electrical continuity over 700 interconnections with diameter down to 50 μm. We demonstrate high reliability of the process with microstructural observations, tomography X and thermal cycle up to 200 cycles without breakdown.

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Section: Introductionmentioning

confidence: 99%

Development and Characterizations of Fine Pitch Flip-Chip Interconnection Using Silver Sintering

Gougeon,

Souriau,

Mendizabal

et al. 2024

IMAPSource Proceedings

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“…In advanced 2.5D/3D packaging technology, the pitch size of Cu pillars is less than 20 μm [ 6 ]. Soldering can no longer meet the needs of such micro-joints, so all-Cu interconnect technology for next-generation interconnect nodes has been developed.…”

Section: Introductionmentioning

confidence: 99%

A Study of Electroplated Nanoporous Copper Using Aberration-Corrected Transmission Electron Microscopy

Wang,

et al. 2024

Nanomaterials

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Nanoporous Cu foam is widely applied in many fields such as the packaging of electronic power devices. In this study, a sandwich-structured Cu-Zn eutectic alloy precursor composed of Cu0.53Zn0.47/Cu5Zn8/Cu0.53Zn0.47 is prepared through electroplating. The surface layer of the precursor, Cu0.53Zn0.47, has a flat surface with numerous grain boundaries, which effectively promotes its dealloying behavior. By contrast, Cu5Zn8 has a porous structure, which promotes the dealloying behavior at the center of the precursor. The dealloying of Cu0.53Zn0.47 is dominated by the coherent surface diffusion of Cu atoms, and the crystal lattice and orientation show no changes before and after dealloying. By contrast, the dealloying behavior of Cu5Zn8 requires the renucleation of Cu crystals; in this process, Cu atoms are transported to the surface of the layer by capillary forces to form clusters, which nucleate and grow.

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Effect of Various Parameters on the Shear Strength of Solid-State Nanoporous Cu Bonding in Cu–Cu Disks for Power Device Packaging

Park

Han

Saito

et al. 2022

J. Electron. Mater.

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Nanoparticle sintering is considered a promising alternative bonding method to Pb-based soldering for the attachment of components in high-temperature electronic devices. However, the technology still poses certain challenges, such as di culty controlling joint thickness and the generation of voids owing to solvent evaporation. In this study, a solid-state (solvent-free), nanoporous-Cu (NPC) bonding method was examined. The effect of bonding temperatures (200-400°C) and atmospheres (N 2 or formic acid) on the shear strength of joints formed between NPC sheets and bare Cu disks were investigated by scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. It was shown that the bondability of NPC under an N 2 atmosphere is closely related to the oxide layer formed on its surface that impairs the diffusion of Cu atoms between the NPC and Cu substrate. Furthermore, the coarsening of the NPC microstructure under a formic acid atmosphere at ≥ 350°C owing to the rapid diffusion of Cu atoms and accompanying plastic deformation induced by surface stress enhances the shear strength of the resulting NPC/Cu joint. The shear strength of NPC/Cu joints formed under a formic acid atmosphere increased from 14.1 to 35.9 MPa with increasing bonding temperature. Based on the results of the investigation, a mechanism was proposed to explain the superiority of the Cu-Cu joints achieved using this method.

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Low-temperature all-Cu interconnections formed by pressure-less sintering of Cu-pillars with nanoporous-Cu caps

Cited by 9 publications

References 13 publications

Development and Characterizations of Fine Pitch Flip-Chip Interconnection Using Silver Sintering

Development and Characterizations of Fine Pitch Flip-Chip Interconnection Using Silver Sintering

A Study of Electroplated Nanoporous Copper Using Aberration-Corrected Transmission Electron Microscopy

Effect of Various Parameters on the Shear Strength of Solid-State Nanoporous Cu Bonding in Cu–Cu Disks for Power Device Packaging

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