The reliability of ultrasonic bonded Cu to Cu electrode for 3D TSV stacking

Myung, Woo‐Ram; Kim, Kyung-Yeol; Kim, Yong‐Il; Jung, Seung‐Boo

doi:10.1007/s10854-017-7558-2

Cited by 7 publications

(3 citation statements)

References 21 publications

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“…This indicates that when the equivalent strain is highly concentrated at the corner of a workpiece, the resulting deformation becomes less even [ 13 ]. Myung et al [ 14 ] considered thermal cycle parameters in finite element analysis (FEA) of Cu/Cu bonds, the formation of cracks could be predicted.…”

Section: Introductionmentioning

confidence: 99%

Geometrical Effects on Ultrasonic Al Bump Direct Bonding for Microsystem Integration: Simulation and Experiments

Lee

Hung

et al. 2021

Micromachines

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This study employed finite element analysis to simulate ultrasonic metal bump direct bonding. The stress distribution on bonding interfaces in metal bump arrays made of Al, Cu, and Ni/Pd/Au was simulated by adjusting geometrical parameters of the bumps, including the shape, size, and height; the bonding was performed with ultrasonic vibration with a frequency of 35 kHz under a force of 200 N, temperature of 200 °C, and duration of 5 s. The simulation results revealed that the maximum stress of square bumps was greater than that of round bumps. The maximum stress of little square bumps was at least 15% greater than those of little round bumps and big round bumps. An experimental demonstration was performed in which bumps were created on Si chips through Al sputtering and lithography processes. Subtractive lithography etching was the only effective process for the bonding of bumps, and Ar plasma treatment magnified the joint strength. The actual joint shear strength was positively proportional to the simulated maximum stress. Specifically, the shear strength reached 44.6 MPa in the case of ultrasonic bonding for the little Al square bumps.

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Section: Introductionmentioning

confidence: 99%

Geometrical Effects on Ultrasonic Al Bump Direct Bonding for Microsystem Integration: Simulation and Experiments

Lee

Hung

et al. 2021

Micromachines

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“…Thus, problems in electronic devices pertain not only to high-temperature environments but also to thermal fatigue caused by the thermal stress occurring in copper/copper joints, i.e., the Cu substrate and Cu terminals. Although several studies involving thermal cycling tests of ultrasonically bonded copper joints have been conducted, no study discusses the decrease in the strength of the copper/copper joint before and after the thermal stability test [10,11]. This is because a sound joint was formed via ultrasonic bonding using high input energy in conventional studies, which has complicated the evaluation and understanding of the mechanism of thermal fatigue failure in ultrasonically bonded joints.…”

Section: Introductionmentioning

confidence: 99%

Thermal Fatigue Properties of Ultrasonically Bonded Copper Joints

et al. 2019

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Thermal fatigue generally occurs in ultrasonically bonded copper joints in electronic devices as the bonding substrate is composed of plural materials, leading to differences in the coefficient of thermal expansion. In this study, we found that the thermal fatigue resistance of the ultrasonically bonded copper joints was influenced by the grain size and hardness of the bonding substrate through the evaluation of the thermal fatigue properties. Copper alloys C1020 and C1940 were used as substrate materials to investigate the influence of the initial properties of the bonding material on the thermal fatigue resistance. We evaluated the crack propagation due to thermal fatigue via thermal cycle tests. Microstructural observations of the region fractured because of thermal fatigue revealed that cracks resulting from thermal fatigue did not progress in the fine grain region formed at the bonded interface. It was inferred that grain boundaries were an obstacle to crack propagation. C1940 has higher hardness and finer grains than C1020, and showed a lower decreasing rate of the peel strength and bonding area after the thermal cycling test than C1020 joints. Thus, a hard copper material with fine grains is effective in suppressing thermal fatigue fracture of ultrasonically bonded copper joints.

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“…7,8 The mismatch of the coefficient of thermal expansion(CTE) between Cu of the micro via and the silicon substrate is one concern of the 3D packaging in the aspect of the reliability. 9 Thermal mismatch between Cu of the micro via and the silicon substrate can result in delamination or cracks in the micro via interconnection. 10 Material property modification of the interconnectors is a method to solve such a problem.…”

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confidence: 99%

Experimental Analysis of the Co-Deposition of Metal Cu and Nano-Sized SiC Particles with CTAB in Micro Via Filling

Wu¹,

Li²,

Wang³

et al. 2019

J. Electrochem. Soc.

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Micro via interconnection is the core of the three-dimensional (3D) packaging. The material property of the interconnection is the decisive factor of chip reliability. In this study, an innovative material modification method for micro via filling is proposed by adopting the co-deposition of metal copper (Cu) and SiC nanoparticles. Investigations focuse on defect-free filling of micro via with co-deposition method and the controllable nanoparticle amount in the nanocomposite. Cetyltrimethylammonium bromide (CTAB) is found having significant inhibition effect on Cu electrodeposition, and it is used as suppressor to avoid defects in micro via. By adjusting pH condition of the electrolyte, the absolute zeta potential of nanoparticles is increased, and agglomeration of nanoparticles is reduced. Experimental results indicate that the content of SiC nanoparticles incorporated in the nanocomposite is greatly enhanced by adding CTAB into the electrolyte, as the CTAB modified the zeta potential of these particles from negative into positive. Other factors affecting the content of SiC nanoparticle in the nanocomposite are investigated. Experimental results show that: 1) current density and duty cycle of pulse direct current (PDC) have great influence on the amount of nanoparticles in the nanocomposite; 2) ultrasound is an effective assistance facilitating the process of metal/nanoparticle co-deposition.

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The reliability of ultrasonic bonded Cu to Cu electrode for 3D TSV stacking

Cited by 7 publications

References 21 publications

Geometrical Effects on Ultrasonic Al Bump Direct Bonding for Microsystem Integration: Simulation and Experiments

Geometrical Effects on Ultrasonic Al Bump Direct Bonding for Microsystem Integration: Simulation and Experiments

Thermal Fatigue Properties of Ultrasonically Bonded Copper Joints

Experimental Analysis of the Co-Deposition of Metal Cu and Nano-Sized SiC Particles with CTAB in Micro Via Filling

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