Investigation of Wet Pretreatment to Improve Cu-Cu Bonding for Hybrid Bonding Applications

Hung, Tzu-Heng; Kang, Ting-Cih; Mao, Shan-Yu; Chou, Teh-Ying; Hu, Han‐Wen; Chiu, Hsih-Yang; Shih, Chiang-Lin; Chen, Kuan‐Neng

doi:10.1109/ectc32696.2021.00121

Cited by 11 publications

(3 citation statements)

References 9 publications

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“…To improve the bonding performance, various chemical pretreatments have been investigated to lower the Cu-Cu bonding temperature by removing surface oxides [15][16][17][18]. K.-N. Chen's group has analyzed and compared the effects of some acids on Cu-Cu bonding through the TCB process; the pretreatments include citric acid, hydrochloric acid, acetic acid, and sulfuric acid [19]. Figure 1 shows the cross-sectional view of scanning electron microscope (SEM) images and scanning acoustic tomography (SAT) analysis of chip-level Cu-Cu bonding with different chemical treatments.…”

Section: Surface Pretreatment For Cu-cu Bondingmentioning

confidence: 99%

Cu-Based Thermocompression Bonding and Cu/Dielectric Hybrid Bonding for Three-Dimensional Integrated Circuits (3D ICs) Application

Huang,

Lin,

Hsiung

et al. 2023

Nanomaterials

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Advanced packaging technology has become more and more important in the semiconductor industry because of the benefits of higher I/O density compared to conventional soldering technology. In advanced packaging technology, copper–copper (Cu-Cu) bonding has become the preferred choice due to its excellent electrical and thermal properties. However, one of the major challenges of Cu-Cu bonding is the high thermal budget of the bonding process caused by Cu oxidation, which can result in wafer warpage and other back-end-of-line process issues in some cases. Thus, for specific applications, reducing the thermal budget and preventing Cu oxidation are important considerations in low-temperature hybrid bonding processes. This paper first reviews the advancements in low-temperature Cu-based bonding technologies for advanced packaging. Various low-temperature Cu-Cu bonding techniques such as surface pretreatment, surface activation, structure modification, and orientation control have been proposed and investigated. To overcome coplanarity issues of Cu pillars and insufficient gaps for filling, low-temperature Cu-Cu bonding used, but it is still challenging in fine-pitch applications. Therefore, low-temperature Cu/SiO2, Cu/SiCN, and Cu/polymer hybrid bonding have been developed for advanced packaging applications. Furthermore, we present a novel hybrid bonding scheme for metal/polymer interfaces that achieves good flatness and an excellent bonding interface without the need for the chemical mechanical polishing (CMP) process.

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Section: Surface Pretreatment For Cu-cu Bondingmentioning

confidence: 99%

Cu-Based Thermocompression Bonding and Cu/Dielectric Hybrid Bonding for Three-Dimensional Integrated Circuits (3D ICs) Application

Huang,

Lin,

Hsiung

et al. 2023

Nanomaterials

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“…The experimental results indicate that hydrochloric acid removes copper oxide but with increasing surface roughness. Hung et al (2021) horizontal contrast acetic acid (CH 3 COOH), hydrochloric acid, citric acid (C 6 H 8 O 7 ) and sulfuric acid (H 2 SO 4 ). Citric acid and acetic acid can react with CuO and Cu 2 O to yield Cu 3 (C 6 H 5 O 7 ) 2 and Cu(CH 3 COO) 2 , respectively, and sulfuric acid converts copper oxide to CuSO 4 .…”

Section: Wet Treatment and Plasma-assisted Bondingmentioning

confidence: 99%

“…(a) TEM image of Cu-Cu bonding without a Si layer (He et al , 2016b); (b) cross-sectional FIB analyses of Cu-Cu bonding treated by citric acid (Hung et al , 2021); (c) schematic diagram of the “adhesive-first” bonding strategy (He et al , 2017a); (d) copper bonding temperature-time map (He et al , 2017a); (e) schematic diagram of the PAB method treatment (Chua et al , 2019)…”

Section: Figurementioning

confidence: 99%

Recent progress on bumpless Cu/SiO₂ hybrid bonding for 3D heterogeneous integration

Kang

Niu

et al. 2022

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Purpose Bumpless Cu/SiO2 hybrid bonding, which this paper aims to, is a key technology of three-dimensional (3D) high-density integration to promote the integrated circuits industry’s continuous development, which achieves the stacks of chips vertically connected via through-silicon via. Surface-activated bonding (SAB) and thermal-compression bonding (TCB) are used, but both have some shortcomings. The SAB method is overdemanding in the bonding environment, and the TCB method requires a high temperature to remove copper oxide from surfaces, which increases the thermal budget and grossly damages the fine-pitch device. Design/methodology/approach In this review, methods to prevent and remove copper oxidation in the whole bonding process for a lower bonding temperature, such as wet treatment, plasma surface activation, nanotwinned copper and the metal passivation layer, are investigated. Findings The cooperative bonding method combining wet treatment and plasma activation shows outstanding technological superiority without the high cost and additional necessity of copper passivation in manufacture. Cu/SiO2 hybrid bonding has great potential to effectively enhance the integration density in future 3D packaging for artificial intelligence, the internet of things and other high-density chips. Originality/value To achieve heterogeneous bonding at a lower temperature, the SAB method, chemical treatment and the plasma-assisted bonding method (based on TCB) are used, and surface-enhanced measurements such as nanotwinned copper and the metal passivation layer are also applied to prevent surface copper oxide.

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Huo¹,

Liu²,

Ouyang³

2022

Advanced Driver Assistance Systems and Autonomous Vehicles

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Investigation of Wet Pretreatment to Improve Cu-Cu Bonding for Hybrid Bonding Applications

Cited by 11 publications

References 9 publications

Cu-Based Thermocompression Bonding and Cu/Dielectric Hybrid Bonding for Three-Dimensional Integrated Circuits (3D ICs) Application

Cu-Based Thermocompression Bonding and Cu/Dielectric Hybrid Bonding for Three-Dimensional Integrated Circuits (3D ICs) Application

Recent progress on bumpless Cu/SiO₂ hybrid bonding for 3D heterogeneous integration

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Investigation of Wet Pretreatment to Improve Cu-Cu Bonding for Hybrid Bonding Applications

Cited by 11 publications

References 9 publications

Cu-Based Thermocompression Bonding and Cu/Dielectric Hybrid Bonding for Three-Dimensional Integrated Circuits (3D ICs) Application

Cu-Based Thermocompression Bonding and Cu/Dielectric Hybrid Bonding for Three-Dimensional Integrated Circuits (3D ICs) Application

Recent progress on bumpless Cu/SiO2 hybrid bonding for 3D heterogeneous integration

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Recent progress on bumpless Cu/SiO₂ hybrid bonding for 3D heterogeneous integration