Hybrid Cu-to-Cu bonding with nano-twinned Cu and non-conductive paste

Kuo, Yu-Hao; Tran, Dinh-Phuc; Ong, Jia-Juen; Tu, King‐Ning; Chen, Chih

doi:10.1016/j.jmrt.2022.03.009

Cited by 16 publications

(5 citation statements)

References 56 publications

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“…2 shows the FIB cross-section images of nt-Cu annealing at 200, 300, and even 400 C for 2 h. The nt-Cu structure upholds under all these annealing conditions. Literature shows that nt-Cu performs better in electromigration [13][14][15], and this stable nt-Cu structure in a wide range of temperatures benefits the device's electromigration resistance. In addition to the stable structure, the coating impurity is low.…”

Section: A Gen 1 Nanotwinned Cumentioning

confidence: 99%

See 1 more Smart Citation

Transforming WLP Applications: Introducing Cutting-Edge Next-Generation Nanotwinned Copper Processes to Revolutionize Hybrid Bonding

Ye,

Han,

Braye

et al. 2024

Journal of Microelectronics and Electronic Packaging

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We discuss two electrochemical plating approaches for nanotwinned copper (ECP nt-Cu)—Gen 1 and Gen 2. These two approaches allow control over columnar width and transition layer thickness on Cu substrates, enabling the filling of nanotwinned Cu for bonding applications. Both approaches produce stable nt-Cu structures with minimal transition layers when electroplated on (111) Cu substrate. However, grain size, transition layer thickness on polycrystalline substrates, and feature-filling behavior differ. The researchers suggest that the choice between Gen 1 and Gen 2 depends on the feature size, aspect ratio, and applications. In addition, further exploration into other additives improves bottom-up filling capabilities, enabling more versatility for applications. Both approaches enable the filling of nanotwinned Cu inside bottom-seeded and complete-seeded features, with 100% nanotwin growth parallel to the substrate for bottomseeded features. However, nanotwin growth percentage and direction depend on feature size and aspect ratio for complete-seeded features. Gen 2 tends to have less sidewall growth due to its smaller grain size and is more compatible with other additives, making it promising for high aspect ratio small features.

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Section: A Gen 1 Nanotwinned Cumentioning

confidence: 99%

“…It can offer lower temperatures for the Cu-Cu direct bonding because its (111) plane-dominated texture has higher atomic diffusivity, leading to a lower thermal budget [6][7][8][9][10]. It also possesses excellent mechanical properties and better electromigration resistance, crucial for device reliability [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Transforming WLP Applications: Introducing Cutting-Edge Next-Generation Nanotwinned Copper Processes to Revolutionize Hybrid Bonding

Ye,

Han,

Braye

et al. 2024

Journal of Microelectronics and Electronic Packaging

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“…Reportedly, nano-twinned Cu bonding satisfies all these requirements. [98][99][100][101] One study compared the microstructures of directly bonded nanotwinned and normal-grained Cu (Fig. 15a).…”

Section: Applications Of Twinned Cu In the Fabrication Of Electronic ...mentioning

confidence: 99%

“…Another study highlighted the importance of defect-free bonding. 100 The authors used two-step heat treatment at different temperatures and for different times to form Cu bonds and characterized the bonding interphase formed between two nanotwinned Cu films. The left graph in Fig.…”

Section: Applications Of Twinned Cu In the Fabrication Of Electronic ...mentioning

confidence: 99%

Electrodeposition of Nano-Twinned Cu and their Applications in Electronics

Park¹,

Eom²,

Kim³

et al. 2022

J. Electrochem. Soc.

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Twin boundaries are planar defects between two domains exhibiting mirror symmetry. Nano-twinned metallic materials contain numerous twin boundaries in parent grains exhibiting submicrometer twin spacing. Owing to their unique mechanical and electrical properties, nano-twinned metals have been studied extensively. Although the mechanical strength of the metal can be drastically increased by shrinking grains, nanocrystalline metals lose their ductility (i.e., the strength–ductility tradeoff), and their electrical conductivity is considerably lowered owing to electron scattering at dense grain boundaries. However, nano-twinned metallic materials can overcome these limitations and exhibit excellent strength, ductility, and electrical conductivity. In this paper, the structure and properties of nano-twinned Cu films are reviewed, and direct current and pulse electrodeposition for forming twin boundaries in Cu films and controlling the twin structure and thickness are summarized. Furthermore, the applications of nano-twinned Cu materials for fabricating electronics are presented.

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“…Copper (Cu) with great electrical and thermal conductivity, electromigration resistance 18 – 21 and mechanical strength is widely employed in metal direct bonding 22 or hybrid bonding 23 – 25 . Currently, Cu/SiO 2 hybrid bonding is already in the production line of complementary metal-oxide semiconductor (CMOS) image sensors by SONY Inc. 26 .…”

Section: Introductionmentioning

confidence: 99%

Enhancement of fatigue resistance by recrystallization and grain growth to eliminate bonding interfaces in Cu–Cu joints

Ong

Tran

Lan

et al. 2022

Sci Rep

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Cu–Cu joints have been adopted for ultra-high density of packaging for high-end devices. However, cracks may form and propagate along the bonding interfaces during fatigue tests. In this study, Cu–Cu joints were fabricated at 300 °C by bonding 〈111〉-oriented nanotwinned Cu microbumps with 30 μm in diameter. After temperature cycling tests (TCTs) for 1000 cycles, cracks were observed to propagate along the original bonding interface. However, with additional 300 °C-1 h annealing, recrystallization and grain growth took place in the joints and thus the bonding interfaces were eliminated. The fatigue resistance of the Cu–Cu joints is enhanced significantly. Failure analysis shows that cracks propagation was retarded in the Cu joints without the original bonding interface, and the electrical resistance of the joints did not increase even after 1000 cycles of TCT. Finite element analysis was carried to simulate the stress distribution during the TCTs. The results can be correlated to the failure mechanism observed by experimental failure analysis.

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Hybrid Cu-to-Cu bonding with nano-twinned Cu and non-conductive paste

Cited by 16 publications

References 56 publications

Transforming WLP Applications: Introducing Cutting-Edge Next-Generation Nanotwinned Copper Processes to Revolutionize Hybrid Bonding

Transforming WLP Applications: Introducing Cutting-Edge Next-Generation Nanotwinned Copper Processes to Revolutionize Hybrid Bonding

Electrodeposition of Nano-Twinned Cu and their Applications in Electronics

Enhancement of fatigue resistance by recrystallization and grain growth to eliminate bonding interfaces in Cu–Cu joints

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