Tensile Properties and Thermal Stability of Unidirectionally &lt;111&gt;-Oriented Nanotwinned and &lt;110&gt;-Oriented Microtwinned Copper

Li, Yu Jin; Tu, K. N.; Chen, Chih

doi:10.3390/ma13051211

Cited by 37 publications

(14 citation statements)

References 20 publications

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“…With ultra-high surface diffusivity, excellent Cu-Cu bonds can be achieved at 200 °C by wafer-to-wafer bonding. Such a bonding process with different adjustments of parameters was demonstrated to provide excellent mechanical properties [ 18 , 19 , 20 , 21 , 22 ] and high resistance in electromigration [ 18 , 23 ].…”

Section: Resultsmentioning

confidence: 99%

Low-Temperature Cu/SiO2 Hybrid Bonding with Low Contact Resistance Using (111)-Oriented Cu Surfaces

et al. 2022

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We adopted (111)-oriented Cu with high surface diffusivity to achieve low-temperature and low-pressure Cu/SiO2 hybrid bonding. Electroplating was employed to fabricate arrays of Cu vias with 78% (111) surface grains. The bonding temperature can be lowered to 200 °C, and the pressure is as low as 1.06 MPa. The bonding process can be accomplished by a 12-inch wafer-to-wafer scheme. The measured specific contact resistance is 1.2 × 10−9 Ω·cm2, which is the lowest value reported in related literature for Cu-Cu joints bonded below 300 °C. The joints possess excellent thermal stability up to 375 °C. The bonding mechanism is also presented to provide more understanding on hybrid bonding.

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Section: Resultsmentioning

confidence: 99%

Low-Temperature Cu/SiO2 Hybrid Bonding with Low Contact Resistance Using (111)-Oriented Cu Surfaces

et al. 2022

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“…However, formation of variously large defects and high impurity of Cu are inevitable. Additionally, most of the previous studies focused on the influences of current density and electroplating temperature [ 23 , 24 , 25 , 26 ]. To date, the effect of Cu ion concentration on the microstructure and mechanical properties of nt-Cu foils has not been fully investigated.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cu Ion Concentration on Microstructures and Mechanical Properties of Nanotwinned Cu Foils Fabricated by Rotary Electroplating

2021

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Rotary electroplating was employed to fabricate high-strength nanotwinned copper (nt-Cu) foils serving as a current collector for high energy-density lithium ion batteries (LIBs). The effect of Cu ion concentration on the microstructural and mechanical properties of the nt-Cu foils was then investigated. Formation of nano-scaled grains was found at the bottom. Its size gradually increases toward the top surface to form a microstructural mixture of gradient nano-scaled and columnar grains in the upper region. Experimental results show that the grains and elongation of the nt-Cu foils increase with increasing concentration of Cu ions. However, a trade-off between tensile strength and elongation is present. The elongation of nt-Cu foils has been enhanced by 22% (from 3.1% to 3.8%) while 8.3% and 3.9% reductions in ultimate tensile strength (UTS) and yield stress (YS) are seen. The current study shows a promising method to tune and optimize the microstructure and mechanical properties of such nt-Cu foils for various applications.

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“…High-strength nanotwinned Cu (nt-Cu) [25][26][27][28] was demonstrated to possess low bonding temperature and electrical resistance [28][29][30][31][32]. The (111) surface can be well controlled through electroplating [30].…”

Section: Introductionmentioning

confidence: 99%

Failure Mechanisms of Cu–Cu Bumps under Thermal Cycling

Shie

Hsu

et al. 2021

Materials

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The failure mechanisms of Cu–Cu bumps under thermal cycling test (TCT) were investigated. The resistance change of Cu–Cu bumps in chip corners was less than 20% after 1000 thermal cycles. Many cracks were found at the center of the bonding interface, assumed to be a result of weak grain boundaries. Finite element analysis (FEA) was performed to simulate the stress distribution under thermal cycling. The results show that the maximum stress was located close to the Cu redistribution lines (RDLs). With the TiW adhesion layer between the Cu–Cu bumps and RDLs, the bonding strength was strong enough to sustain the thermal stress. Additionally, the middle of the Cu–Cu bumps was subjected to tension. Some triple junctions with zig-zag grain boundaries after TCT were observed. From the pre-existing tiny voids at the bonding interface, cracks might initiate and propagate along the weak bonding interface. In order to avoid such failures, a postannealing bonding process was adopted to completely eliminate the bonding interface of Cu–Cu bumps. This study delivers a deep understanding of the thermal cycling reliability of Cu–Cu hybrid joints.

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Tensile Properties and Thermal Stability of Unidirectionally <111>-Oriented Nanotwinned and <110>-Oriented Microtwinned Copper

Cited by 37 publications

References 20 publications

Low-Temperature Cu/SiO2 Hybrid Bonding with Low Contact Resistance Using (111)-Oriented Cu Surfaces

Low-Temperature Cu/SiO2 Hybrid Bonding with Low Contact Resistance Using (111)-Oriented Cu Surfaces

Effect of Cu Ion Concentration on Microstructures and Mechanical Properties of Nanotwinned Cu Foils Fabricated by Rotary Electroplating

Failure Mechanisms of Cu–Cu Bumps under Thermal Cycling

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