Low-Loss Characteristics of Metal-Foil-Based Passive Components by Surface-Activated Bonding Technologies

Matsuura, Keita; Liang, Jianbo; Maezawa, Koichi; Shigekawa, Naoteru

doi:10.1109/ted.2019.2928620

Cited by 5 publications

(4 citation statements)

References 22 publications

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“…In this article, the fabrication of junctions using SAB technologies as well as their characterization was discussed 120) with emphasis on the response of bonding interfaces to thermal annealing. Results for Si//Si, GaAs//Si, SiC//Si, diamond//Si, diamond//GaN, diamond//Cu, and Al//sapphire junctions in our group were described.…”

Section: Discussionmentioning

confidence: 99%

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Heterojunctions fabricated by surface activated bonding–dependence of their nanostructural and electrical characteristics on thermal process

Shigekawa¹,

Liang²,

Ohno

2022

Jpn. J. Appl. Phys.

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Recent achievements in research of heterojunctions fabricated using surface activated bonding (SAB), one of the practically useful direct wafer bonding technologies, are discussed. The response of bonding interfaces to post-bonding annealing is focused. These junctions reveal high thermal tolerance (1000 ○C in case of junctions made of widegap materials) despite difference in coefficients of thermal expansion between bonded materials. Defect layers with a several-nm thickness formed by the surface activation process at the as-bonded interfaces get faint and their electrical and mechanical properties are improved by annealing. These results show that as bonded interfaces are in a metastable state, and novel functional devices are likely to be realized by applying wafer processing steps to SAB-based junctions. Characteristics of III-V//Si multijunction solar cells, GaN-on-diamond high electron mobility transistors, and metal-foil based low-loss interconnects that are fabricated by processing SAB-based junctions are described, and the future prospects are presented.

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Section: Discussionmentioning

confidence: 99%

“…(Color online) (a) Insertion-loss characteristics of 17 μm Al-foil and 1 μm evaporated Al film-based CPWs at 20 GHz. (b) Q-factors of INDs with 18.8 mm signal lines 120).…”

mentioning

confidence: 99%

Heterojunctions fabricated by surface activated bonding–dependence of their nanostructural and electrical characteristics on thermal process

Shigekawa¹,

Liang²,

Ohno

2022

Jpn. J. Appl. Phys.

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“…The loss at dozens of GHz is determined by resistance of metal layers. For example, coplanar waveguides and high-Q inductors require tens-micron-thick metal layers, to obtain lower ohmic losses [2]. Cu is popular as the metal interconnection layer in the circuit because it provides low loss and high conductivity, as well as excellent thermal reliability and low cost [3].…”

Section: Introductionmentioning

confidence: 99%

Low-temperature bonding of surface-activated polyimide to Cu Foil in Pt-catalyzed formic acid atmosphere

Meng

Yang

Gao

et al. 2021

J Mater Sci: Mater Electron

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In this study, a two-step process involving oxygen plasma surface activation and thermos-compression in Pt-catalyzed formic acid gas was used to bond Cu foil and polyimide. The oxygen plasma was used to activate the polyimide surface to achieve strong adhesion with sputtered deposition film, and the Ptcatalyzed formic acid gas removed the oxides on the Cu surface effectively to promote bonding between Cu foil and polyimide. Via this method, a void-less bonding with a maximum shear strength of 20.31 MPa was achieved. The plasma bombardment was found to promote the formation of C-O-Cr and N-Cr bonds between polyimide and deposition metals, which improved their adhesion. After shear test, striped metal films remained on fracture surfaces at both polyimide and Cu foil sides, suggesting the fracture mainly occurred within adhered deposition metals rather than at bonding interface. This low-temperature bonding method is promising to achieve the direct integration between polyimide and copper foil without adhesive, which plays a key role in flexible device integration.

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“…We also bonded Al foils with t of 17 μm to sapphire substrates and fabricated CPWs and inductors. 21,22) Their RF characteristics outperformed those of components made by evaporating Al layers with a thickness of 1 μm. We recently fabricated CPWs on HR Si substrates by directly bonding Al foils and examined their RF characteristics.…”

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confidence: 99%

Low-loss characteristics of coplanar waveguides fabricated by directly bonding metal foils to high-resistivity Si substrates

Yonekura¹,

Kawamoto²,

Liang³

et al. 2022

Jpn. J. Appl. Phys.

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Coplanar waveguides (CPWs) are fabricated by directly bonding 17-m Al foils to Si substrates with different resistivities and wet etching. Their RF characteristics are compared with those of CPWs fabricated on 0.8-m thick evaporated Al layers. A lower insertion loss is observed for Si substrates with higher resistivity irrespective of thickness of conductors because the substrate loss is decreased. For a 10000-Ω·cm Si substrate, Al-foil-based CPWs reveal a ∼0.7-dB/cm lower insertion loss in comparison with evaporated-Al-based CPWs at 1 GHz. These features agree with calculation, which implies the superiority of direct bonding of metal foils for realizing low-loss passive components.

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Low-Loss Characteristics of Metal-Foil-Based Passive Components by Surface-Activated Bonding Technologies

Cited by 5 publications

References 22 publications

Heterojunctions fabricated by surface activated bonding–dependence of their nanostructural and electrical characteristics on thermal process

Heterojunctions fabricated by surface activated bonding–dependence of their nanostructural and electrical characteristics on thermal process

Low-temperature bonding of surface-activated polyimide to Cu Foil in Pt-catalyzed formic acid atmosphere

Low-loss characteristics of coplanar waveguides fabricated by directly bonding metal foils to high-resistivity Si substrates

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