Low-Temperature (70°C) Cu-to-Cu Direct Bonding by Capping Metal Layers

Liu, Demin; Chen, Po-Chih; Liu, Yuwei; Hu, Han‐Wen; Kuan-Neng, Chen

doi:10.1109/led.2021.3105434

Cited by 18 publications

(3 citation statements)

References 18 publications

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“…Previously, a variety of passivation materials, including Au, Cr/Au, Pd, Ag, Pt, and Ti 9 – 11 , 14 – 17 , have been utilized. However, these materials have been primarily investigated solely for their role in enhancing bonding quality and electrical properties within homogeneous materials.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, various metal materials were used to compare the differences in diffusion behavior. Noble metal Pt with good Cu diffusion 15 , Ti that has been studied a lot with excellent diffusion capability 16 , Ta that is also used as a diffusion barrier 18 , and Cr that is also used as a wetting layer because of its smooth roughness 14 , 17 were selected. Pt and Ta materials were chosen as exemplary candidates for highlighting disparities between materials with robust diffusion and those with limited diffusion.…”

Section: Introductionmentioning

confidence: 99%

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Unraveling diffusion behavior in Cu-to-Cu direct bonding with metal passivation layers

Jeong,

Park,

Kim

et al. 2024

Sci Rep

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Cu/SiO2 hybrid bonding presents a promising avenue for achieving high-density interconnects by obviating the need for microbumps and underfills. Traditional copper bonding methods often demand temperatures exceeding 400 °C, prompting recent endeavors to mitigate bonding temperatures through investigations into metal passivation bonding. In this study, we scrutinized the diffusion behavior associated with various metal passivation layers (Platinum, Titanium, Tantalum, and Chromium) in the context of low-temperature direct copper bonding and delved into the essential bonding mechanisms. We observed a deviation from conventional metal–metal bonding factors, such as surface roughness and grain size, in the diffusion behavior. Remarkably, our analysis revealed a pronounced correlation between the crystallinity of the metal passivation layers and diffusion behavior, surpassing the influence of other experimental factors. Subsequent post-bonding examinations corroborated consistent diffusion behavior in Pt and Cr passivation samples with disparate crystallinities, reinforcing the significance of crystallinity in the bonding process. Our findings underscore crystallinity as a pivotal factor governing diffusion behavior, even under varied bonding conditions. These insights are instrumental in achieving exceptional bonding characteristics at lower temperatures in Cu/SiO2 hybrid bonding. Implications of this study extend to the prospect of advancing highly integrated systems through die-to-wafer bonding, marking a substantial stride toward future applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Unraveling diffusion behavior in Cu-to-Cu direct bonding with metal passivation layers

Jeong,

Park,

Kim

et al. 2024

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Depending on whether the integration is performed at wafer or die level, there are three stacking options in 3D integration: wafer-to-wafer, chip-to-wafer and chip-to-chip [4,5]. At present, metal-to-metal direct bonding technology is an attractive option in the next generation of power devices and 3D IC technology, such as Au-Au, Cu-Cu or Al-Al [6][7][8][9]. Figure 1a shows the 3D view of a basic test structure of bonding technology in 3D integration, which can be applied to process the development of 3D integration prior to ICs' fabrication and monitoring unit of fabricating 3D ICs.…”

Section: Introductionmentioning

confidence: 99%

Extraction of Interface-Trap Densities of the Stacked Bonding Structure in 3D Integration Using High-Frequency Capacitance-Voltage Technique

Guo

Yao

et al. 2022

Micromachines

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An extraction method of the interface-trap densities (Dit) of the stacked bonding structure in 3D integration using high-frequency capacitance–voltage technique is proposed. First, an accurate high-frequency capacitance–voltage model is derived. Next, by numerically solving the charge-balance equation and charge conservation equation, Dit is extracted by fitting the measured and calculated capacitance–voltage curves based on the derived model. Subsequently, the accuracy of the derived model is verified by the agreements between the analytical results and TCAD simulation results. The average extraction error proves the precision and efficiency of the extraction method. Finally, the stacked bonding structure has been fabricated, and Dit at the interface between silicon and insulator is extracted to diagnose and calibrate the fabrication processes.

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Stacking Fault and Plastic Deformation Mechanism in Nano‐twinned Cu Pillar under Ultrahigh Stress

Fu,

Lee,

Chang

et al. 2024

Adv Eng Mater

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Nano‐twinned Cu pillar was fabricated on an as‐electroplated nano‐twinned Cu film, which preferentially grew in the {111} plane family. With a nano‐indentation device (Picoindenter), a vertical ultrahigh pressure of 5100 MPa was applied to the nano‐twinned Cu pillar. The twin lamellar grain was greatly deformed under that ultrahigh external stress. Consequently, the top surface plane was pressed into the lattice beneath to continuously form edge dislocations. Those dislocations were driven along the possible slip systems toward the outer surface of the first matrix lamella, corresponding to the plastic deformation. A dislocation‐mediated mechanism was proposed to explain the plastic deformation of the nano‐twinned Cu pillar. Three types of slip systems were identified for the created dislocations, each resulting in either the displacement on the first matrix lamellar grain or cross‐slip on the twin boundary. At the ultrahigh external pressure, as the dislocations slid through the twin boundary, they would dissociate to Shockley partial dislocations and alter the stacking sequence in the twin boundary, creating stacking faults. The resultant stacking faults in the twin boundary were observed in the TEM lattice images.This article is protected by copyright. All rights reserved.

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Low-Temperature (70°C) Cu-to-Cu Direct Bonding by Capping Metal Layers

Cited by 18 publications

References 18 publications

Unraveling diffusion behavior in Cu-to-Cu direct bonding with metal passivation layers

Unraveling diffusion behavior in Cu-to-Cu direct bonding with metal passivation layers

Extraction of Interface-Trap Densities of the Stacked Bonding Structure in 3D Integration Using High-Frequency Capacitance-Voltage Technique

Stacking Fault and Plastic Deformation Mechanism in Nano‐twinned Cu Pillar under Ultrahigh Stress

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