Details of the Researcher

PHOTO

Kai Takeuchi
Section
Graduate School of Engineering
Job title
Assistant Professor
Degree

  • Ph.D. Engineering (The University of Tokyo)

e-Rad No.
20896716

Research History 5

  • 2026/04 - Present
    Tohoku University　Department of Electronic Engineering, Graduate School of Engineering　Associate Professor

  • 2022/08 - 2026/03
    Tohoku University　Department of Electronic Engineering, Graduate School of Engineering　Assistant Professor

  • 2021/10 - 2022/07
    The University of Tokyo　System Design Lab, School of Engineering　Project Researcher

  • 2020/08 - 2022/07
    The University of Tokyo　Institute of Industrial Science　Collaborative Researcher

  • 2020/04 - 2022/07
    Meisei University　Collaborative Research Center　Senior Researcher

Education 3

  • The University of Tokyo　The Graduate School of Engineering　Department of Precision Engineering

    2017/04 - 2020/03

  • The University of Tokyo　The Graduate School of Engineering　Department of Precision Engineering

    2015/04 - 2017/03

  • The University of Tokyo　The Faculty of Engineering　Department of Precision Engineering

    2011/04 - 2015/04

Committee Memberships 6

  • 一般社団法人 電子実装工学研究所 (IMSI)　接合界面創成技術研究会 幹事

    2024/06 - Present

  • International Conference on Electronics Packaging (ICEP) 論文副委員長

    2023/09 - Present

  • IEEE EPS Symposium Japan (ICSJ) 運営委員

    2023/01 - Present

  • 第41回「センサ・マイクロマシンと応用システム」シンポジウム運営委員 幹事

    2024/01 - 2024/12

  • 電気学会　第40回「センサ・マイクロマシンと応用システム」シンポジウム運営委員 副幹事

    2023/03 - 2023/12

  • International Conference on Electronics Packaging (ICEP) 2023 論文委員

    2022/08 - 2023/06

Show all ︎Show first 5

Professional Memberships 3

  • IEEE EPS

    2023/01 - Present

  • The Institute of Electrical Engineers of Japan

    2023/01 - Present

  • エレクトロニクス実装学会

    2021/03 - Present

Research Interests 7

  • 実装工学

  • Bonding interface

  • Room temperature bonding

  • Surface activated bonding

  • エレクトロニクス実装

  • low temperature bonding

  • wafer bonding

Research Areas 1

  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Electronic devices and equipment /

Awards 9

  1. 石田實記念財団研究奨励賞

    2025/11　石田實記念財団　ポリシラザン転化反応に基づく常温ウェハ接合技術の開発

  2. 優秀ポスター発表賞

    2025/11　電気学会センサ・マイクロマシン部門第42回「センサ・マイクロマシンと応用システム」シンポジウム　金薄膜転写による金めっき膜平滑化における転写膜厚と転写性

  3. ポスターアワード

    2025/03　第34回マイクロエレクトロニクスシンポジウム(MES2024)　Au薄膜の転写とコイニングにより作製した平坦な Auマイクロバンプアレイ

  4. 優秀ポスター発表賞ファイナリスト

    2024/11　電気学会センサ・マイクロマシン部門 第41回「センサ・マイクロマシンと応用システム」シンポジウム　無機ポリマーを用いた水中でのSi基板間の接着

  5. Poster Award of ICEP 2024

    2024/04　The Japan Institute of Electronics Packaging　Investigation of Plasma Gases for Polysilazane Conversion into SiO2 for Wafer Bonding

  6. IEEE EPS Japan Chapter Young Award of ICEP 2024

    2024/04　IEEE Electronics Packaging Society Japan Chapter　Formation of SiO2 Bonding Interface using Perhydropolysilazane at Room Temperature

  7. 若手優秀研究賞

    2024/03　東北大学電気・情報系

  8. Best Presentation Award

    2021/10　The Organizing Committee of 2021 7th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)　Quantification of Wafer Bond Strength of Silicon Nitride under Controlled Atmosphere

  9. Outstanding Student Paper Award

    2016/10　The Electrochemical Society　Modified Surface Activated Bonding Using Si Intermediate Layer for Bonding and Debonding of Glass Substrates

Show all ︎Show 5

Papers 60

  1. Room temperature wafer bonding through conversion of polysilazane into SiO2 Peer-reviewed

    Kai Takeuchi, Tadatomo Suga, Eiji Higurashi

    Scientific Reports　14　(1)　2024/01

    DOI： 10.1038/s41598-024-51800-6 　

    eISSN： 2045-2322

  2. Room temperature bonding of Au assisted by self-assembled monolayer Peer-reviewed

    Kai Takeuchi, Junsha Wang, Beomjoon Kim, Tadatomo Suga, Eiji Higurashi

    Applied Physics Letters　122　(5)　051603-051603　2023/01/30

    Publisher: AIP Publishing

    DOI： 10.1063/5.0128187 　

    ISSN： 0003-6951

    eISSN： 1077-3118

  3. Quantification of wafer bond strength under controlled atmospheres Peer-reviewed

    Kai Takeuchi, Tadatomo Suga

    JAPANESE JOURNAL OF APPLIED PHYSICS　61　(SF)　2022/06

    DOI： 10.35848/1347-4065/ac5e49 　

    ISSN： 0021-4922

    eISSN： 1347-4065

  4. Microfluidic chip connected to porous microneedle array for continuous ISF sampling Peer-reviewed

    Kai Takeuchi, Nobuyuki Takama, Kirti Sharma, Oliver Paul, Patrick Ruther, Tadatomo Suga, Beomjoon Kim

    DRUG DELIVERY AND TRANSLATIONAL RESEARCH　12　(2)　435-443　2022/02

    DOI： 10.1007/s13346-021-01050-0 　

    ISSN： 2190-393X

    eISSN： 2190-3948

  5. Sequential Plasma Activation for Low Temperature Bonding of Aluminosilicate Glass Peer-reviewed

    Kai Takeuchi, Fengwen Mu, Akira Yamauchi, Tadatomo Suga

    ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY　10　(5)　2021/05

    DOI： 10.1149/2162-8777/abfd4b 　

    ISSN： 2162-8769

    eISSN： 2162-8777

  6. Room Temperature Wafer Bonding of Glass Using Aluminum Oxide Intermediate Layer Peer-reviewed

    Kai Takeuchi, Fengwen Mu, Yoshiie Matsumoto, Tadatomo Suga

    ADVANCED MATERIALS INTERFACES　8　(5)　2021/03

    DOI： 10.1002/admi.202001741 　

    ISSN： 2196-7350

  7. Flexible and porous microneedles of PDMS for continuous glucose monitoring Peer-reviewed

    Kai Takeuchi, Nobuyuki Takama, Rie Kinoshita, Teru Okitsu, Beomjoon Kim

    BIOMEDICAL MICRODEVICES　22　(4)　2020/11

    DOI： 10.1007/s10544-020-00532-1 　

    ISSN： 1387-2176

    eISSN： 1572-8781

  8. Microfluidic chip to interface porous microneedles for ISF collection Peer-reviewed

    Kai Takeuchi, Nobuyuki Takama, Beomjoon Kim, Kirti Sharma, Oliver Paul, Patrick Ruther

    BIOMEDICAL MICRODEVICES　21　(1)　2019/03

    DOI： 10.1007/s10544-019-0370-4 　

    ISSN： 1387-2176

    eISSN： 1572-8781

  9. Prebonding Baking of Wafers for Improved Surface Activated Bonding

    Kai Takeuchi, Junsha Wang, Akira Yamauchi, Tadatomo Suga, Eiji Higurashi

    IEEE Transactions on Components, Packaging and Manufacturing Technology　2026/03

    DOI： 10.1109/TCPMT.2026.3662372 　

  10. Au hollow pyramidal bumps for low-temperature low-pressure bonding fabricated via Au film transfer method

    Shintaro Goto, Kai Takeuchi, Le Hac Huong Thu, Takashi Matsumae, Hideki Takagi, Yuichi Kurashima, Eiji Higurashi

    SENSORS AND ACTUATORS A-PHYSICAL　395　2025/12/01

    DOI： 10.1016/j.sna.2025.116968 　

    ISSN： 0924-4247

    eISSN： 1873-3069

  11. Low pressure Au–Au bonding using flat-topped micro-bump Au arrays fabricated by Au film transfer and coining methods Peer-reviewed

    Shintaro Goto, Kai Takeuchi, Le Hac Huong Thu, Takashi Matsumae, Hideki Takagi, Yuichi Kurashima, Eiji Higurashi

    Japanese Journal of Applied Physics　64　(5)　05SP08-05SP08　2025/05/01

    Publisher: IOP Publishing

    DOI： 10.35848/1347-4065/adcc3a 　

    ISSN： 0021-4922

    eISSN： 1347-4065

    More details Close

    Abstract The fabrication of highly functional optical devices requires solid-state, low-pressure bonding techniques. In this study, we developed micro-bump Au arrays that come into close contact at low pressure and facilitate low-temperature bonding. The micro-bumps were fabricated by Au film transfer and coining methods. A high die shear strength was achieved between the Si chip with the micro-bumps and the Si substrate with an Au film under a low bonding pressure of 10 MPa in ambient air at 150 °C after Ar fast-atom beam irradiation. The close contact between the micro-bumps and Au film was confirmed via cross-sectional scanning electron microscopy. Using the micro-bumps, a GaAs laser diode chip with an active layer near the bonding interface was junction-down mounted without degradation. The study findings confirm that the proposed methods can bond dissimilar materials at low bonding pressures, thereby contributing to the integration of optical components.

  12. Wafer Bonding of GaAs and SiC via Thin Au Film at Room Temperature Peer-reviewed

    Kai Takeuchi, Eiji Higurashi

    Micromachines　2025/04/07

    DOI： 10.3390/mi16040439 　

  13. Room temperature bonding of Au plating through surface smoothing using polyimide template stripping Peer-reviewed

    Kai Takeuchi, Shogo Koseki, Le Hac Huong Thu, Takashi Matsumae, Hideki Takagi, Yuichi Kurashima, Takahiro Tsuda, Tomoaki Tokuhisa, Toshikazu Shimizu, Eiji Higurashi

    Sensors and Actuators A: Physical　383　116211-116211　2025/03

    Publisher: Elsevier BV

    DOI： 10.1016/j.sna.2025.116211 　

    ISSN： 0924-4247

  14. Room temperature wafer bonding via polysilazane for vacuum sealing bonding Peer-reviewed

    Kai Takeuchi, Eiji Higurashi

    Japanese Journal of Applied Physics　2025/02/12

    Publisher: IOP Publishing

    DOI： 10.35848/1347-4065/adb4fb 　

    ISSN： 0021-4922

    eISSN： 1347-4065

    More details Close

    Abstract This paper presents a novel room temperature wafer bonding method under vacuum using perhydropolysilazane (PHPS) as an adhesion layer. Vacuum wafer bonding is a critical technique for vacuum-sealed electronics packaging, such as MEMS sensors; however, conventional methods typically require high-temperature processes. In this study, we propose and demonstrate a room temperature wafer bonding approach via PHPS, enabling the formation of a robust SiO2 bonding interface. By utilizing plasma hydrophilic treatment to introduce adsorbed water at the bonding interface, the PHPS layer undergoes conversion to SiO2, even though the bonding is performed under vacuum at room temperature. While analysis of the bonding interface reveals partial desorption of the adsorbed water at the bonding interface due to the vacuum process, the achieved bond strength remains high at 3.98 J/m2. The proposed bonding method offers a promising solution for vacuum-sealing applications in electronics packaging.

  15. Surface smoothing based on Au thin film transfer on rough-surface AlN ceramic substrates for low-temperature bonding

    Shintaro Goto, Shogo Koseki, Kai Takeuchi, Eiji Higurashi

    2025 IEEE 75TH ELECTRONIC COMPONENTS AND TECHNOLOGY CONFERENCE, ECTC　1791-1794　2025

    DOI： 10.1109/ECTC51687.2025.00304 　

    ISSN： 0569-5503

    eISSN： 2377-5726

  16. Plasma Hydrophilic Treatment for Improved Wafer Bonding Strength via Polysilazane

    Nemoto Daiki, Kai Takeuchi, Eiji Higurashi

    2024 International 3D Systems Integration Conference, 3DIC 2024　2024

    DOI： 10.1109/3DIC63395.2024.10830136 　

  17. Formation of Au Hollow Micro-Bump Arrays for Low Temperature Au-Au Bonding

    Shintaro Goto, Kai Takeuchi, Le Hac Huong Thu, Takashi Matsumae, Hideki Takagi, Yuichi Kurashima, Eiji Higurashi

    13th IEEE CPMT Symposium Japan: Innovation of Packaging Technology for Advanced Heterogeneous Integration, ICSJ 2024　150-151　2024

    DOI： 10.1109/ICSJ62869.2024.10804723 　

  18. Adhesion between Si Substrates in Liquid Water Using Inorganic Polymer

    Daiki Nemoto, Kai Takeuchi, Eiji Higurashi

    13th IEEE CPMT Symposium Japan: Innovation of Packaging Technology for Advanced Heterogeneous Integration, ICSJ 2024　168-169　2024

    DOI： 10.1109/ICSJ62869.2024.10804705 　

  19. Sequential Surface Treatment Process with VUV light and Ar Plasma for Room Temperature Au-Au Bonding

    Mika Ogino, Kai Takeuchi, Eiji Higurashi

    13th IEEE CPMT Symposium Japan: Innovation of Packaging Technology for Advanced Heterogeneous Integration, ICSJ 2024　166-167　2024

    DOI： 10.1109/ICSJ62869.2024.10804698 　

  20. Perhydropolysilazane as an Adhesion Layer for Vacuum Sealing Wafer Bonding

    Kai Takeuchi, Daiki Nemoto, Eiji Higurashi

    2024 8th International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2024　2024

    DOI： 10.1109/LTB-3D64053.2024.10774106 　

  21. Template Stripping Process Combined With Polyimide and SiO<inf>2</inf>/Si Templates for Obtaining Smooth Au Surfaces

    Shogo Koseki, Mika Ogino, Kai Takeuchi, Le Hac Huong Thu, Takashi Matsumae, Hideki Takagi, Yuichi Kurashima, Takahiro Tsuda, Tomoaki Tokuhisa, Toshikazu Shimizu, Eiji Higurashi

    2024 International Conference on Electronics Packaging, ICEP 2024　129-130　2024

    DOI： 10.23919/ICEP61562.2024.10535611 　

  22. Investigation of Plasma Gases for Polysilazane Conversion into SiO<inf>2</inf> for Wafer Bonding

    Daiki Nemoto, Kai Takeuchi, Eiji Higurashi

    2024 International Conference on Electronics Packaging, ICEP 2024　289-290　2024

    DOI： 10.23919/ICEP61562.2024.10535633 　

  23. Influence of Various Plasma and UV/O<inf>3</inf>Treatments on Au Surfaces for Au-Au Surface Activated Bonding

    Mika Ogino, Kai Takeuchi, Eiji Higurashi

    2024 International Conference on Electronics Packaging, ICEP 2024　331-332　2024

    DOI： 10.23919/ICEP61562.2024.10535697 　

  24. Formation of SiO<inf>2</inf> Bonding Interface using Perhydropolysilazane at Room Temperature

    Kai Takeuchi, Daiki Nemoto, Tadatomo Suga, Eiji Higurashi

    2024 International Conference on Electronics Packaging, ICEP 2024　113-114　2024

    DOI： 10.23919/ICEP61562.2024.10535553 　

  25. Optimization of Ag Thin Film Thickness with a Capping Layer for Ag-Ag Surface Activated Bonding

    Yuanhao Cai, Kai Takeuchi, Miyuki Uomoto, Takehito Shimatsu, Eiji Higurashi

    2024 International Conference on Electronics Packaging, ICEP 2024　117-118　2024

    DOI： 10.23919/ICEP61562.2024.10535599 　

  26. Suppression of Surface Roughening of Ag Films by Capping Layer for Ag/Ag Surface Activated Bonding Peer-reviewed

    Yuanhao Cai, Kai Takeuchi, Miyuki Uomoto, Takehito Shimatsu, Eiji Higurashi

    2023 IEEE CPMT Symposium Japan (ICSJ)　135-136　2023/11/15

    Publisher: IEEE

    DOI： 10.1109/icsj59341.2023.10339608 　

  27. Template Stripping of Au from Polyimide Film for Smoothing of Bonding Surface Peer-reviewed

    Shogo Koseki, Mika Ogino, Kai Takeuchi, Le Hac Huong Thu, Takashi Matsumae, Hideki Takagi, Yuichi Kurashima, Tomoaki Tokuhisa, Toshikazu Shimizu, Eiji Higurashi

    2023 IEEE CPMT Symposium Japan (ICSJ)　133-134　2023/11/15

    Publisher: IEEE

    DOI： 10.1109/icsj59341.2023.10339541 　

  28. Conversion of Perhydropolysilazane into SiO2 using Plasma Treatment for Wafer Bonding Peer-reviewed

    Kai Takeuchi, Daiki Nemoto, Tadatomo Suga, Eiji Higurashi

    2023 18th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT)　2023/10/25

    Publisher: IEEE

    DOI： 10.1109/impact59481.2023.10348949 　

  29. Hydrophilic Bonding of SiO2/SiO2 and Cu/Cu using Sequential Plasma Activation Peer-reviewed

    Kai Takeuchi, Takeki Ninomiya, Michitaka Kubota, Masaya Kawano, Takeshi Takagi, Niwa Masaaki, Tadahiro Kuroda, Tadatomo Suga

    ECS Transactions　112　(3)　95-101　2023/09/29

    Publisher: The Electrochemical Society

    DOI： 10.1149/11203.0095ecst 　

    ISSN： 1938-5862

    eISSN： 1938-6737

    More details Close

    Hybrid bonding is an indispensable technique for the 3D integration of electronic systems. Cu-to-Cu interconnections and SiO2-to-SiO2 dielectric layers should be bonded simultaneously in the wafer-to-wafer bonding process. In this study, sequential plasma activation (SPA) including O2 plasma, N2 plasma, and N radical is investigated for low-temperature bonding of Cu and TEOS SiO2 at 200°C. The SPA bonding improves the bond strength to more than 1 J/m2 compared to the conventional single gas plasma activation bonding. The surface analysis indicates that SPA forms oxynitrides on TEOS SiO2 surface and Cu oxide with adsorbed water on the Cu surface, facilitating the bonding interface formation. The presented technique will contribute to the hybrid bonding applications at lower temperatures.

  30. Protection of Activated Au Surface using Self-assembled Monolayer for Room Temperature Bonding Peer-reviewed

    Kai Takeuchi, Junsha Wang, Tadatomo Suga, Beomjoon Kim, Eiji Higurashi

    2023 International Conference on Electronics Packaging, ICEP 2023　173-174　2023

    Publisher: IEEE

    DOI： 10.23919/ICEP58572.2023.10129675 　

  31. Removal of Adsorbed Water on Si Wafers for Surface Activated Bonding Peer-reviewed

    Kai Takeuchi, Eiji Higurashi, Junsha Wang, Akira Yamauchi, Tadatomo Suga

    2022 IEEE CPMT Symposium Japan (ICSJ)　61-64　2022/11/09

    Publisher: IEEE

    DOI： 10.1109/icsj55786.2022.10034710 　

  32. A novel strategy for GaN-on-diamond device with a high thermal boundary conductance Peer-reviewed

    Fengwen Mu, Bin Xu, Xinhua Wang, Runhua Gao, Sen Huang, Ke Wei, Kai Takeuchi, Xiaojuan Chen, Haibo Yin, Dahai Wang, Jiahan Yu, Tadatomo Suga, Junichiro Shiomi, Xinyu Liu

    JOURNAL OF ALLOYS AND COMPOUNDS　905　2022/06

    DOI： 10.1016/j.jallcom.2022.164076 　

    ISSN： 0925-8388

    eISSN： 1873-4669

  33. Polishing Diamond Substrates using Gas Cluster Ion Beam (GCIB) Irradiation for the Direct Bonding to Power Devices Peer-reviewed

    Junsha Wang, Kai Takeuchi, Izumi Kataoka, Tadatomo Suga

    2022 International Conference on Electronics Packaging (ICEP)　2022/05/11

    Publisher: IEEE

    DOI： 10.23919/icep55381.2022.9795483 　

  34. Sequential Plasma Activation Bonding of Sapphire using SiO2 Intermediate Layer Peer-reviewed

    Kai Takeuchi, Tadatomo Suga

    2022 International Conference on Electronics Packaging (ICEP)　2022/05/11

    Publisher: IEEE

    DOI： 10.23919/icep55381.2022.9795608 　

  35. Prolongation of the Surface Activation Effect using Self-Assembled Monolayer for Low Temperature Bonding of Au Peer-reviewed

    Kai Takeuchi, Beomjoon Kim, Tadatomo Suga

    2022 IEEE 72nd Electronic Components and Technology Conference (ECTC)　2022/05

    Publisher: IEEE

    DOI： 10.1109/ectc51906.2022.00103 　

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

    Ying Meng, Yang Xu, Runhua Gao, Xinhua Wang, Xiaojuan Chen, Sen Huang, Ke Wei, Dahai Wang, Haibo Yin, Kai Takeuchi, Tadatomo Suga, Fengwen Mu, Xinyu Liu

    JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS　33　(5)　2582-2589　2022/02

    DOI： 10.1007/s10854-021-07463-4 　

    ISSN： 0957-4522

    eISSN： 1573-482X

  37. Quantification of Wafer Bond Strength of Silicon Nitride under Controlled Atmosphere

    Kai Takeuchi, Tadatomo Suga

    2021 7th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)　9-9　2021/10/05

    Publisher: IEEE

    DOI： 10.1109/ltb-3d53950.2021.9598434 　

  38. Demonstration of high thermal performance GaN-on-graphite composite bonded substrate for application in III-V nitride electronics Peer-reviewed

    Lei Li, Tomohiro Obata, Aozora Fukui, Kai Takeuchi, Tadatomo Suga, Atsushi Tanaka, Akio Wakejima

    Applied Physics Express　14　(9)　2021/09

    DOI： 10.35848/1882-0786/ac15c0 　

    ISSN： 1882-0778

    eISSN： 1882-0786

  39. Low temperature bonding of GaN and carbon composite via Au capping layer activated by Ar fast atom bombardment Peer-reviewed

    Kai Takeuchi, Suga Tadatomo, Atsushi Tanaka, Akio Wakejima

    2021 International Conference on Electronics Packaging, ICEP 2021　43-44　2021/05/12

    DOI： 10.23919/ICEP51988.2021.9451955 　

  40. Low temperature bonding of Cu bump to WBG device using the surface activation method Peer-reviewed

    Tadatomo Suga, Kai Takeuchi, Seongbin Shin, Nora Martinez, Yoshinari Ikeda, Akira Hirao, Motohito Hori

    2021 INTERNATIONAL CONFERENCE ON ELECTRONICS PACKAGING (ICEP 2021)　35　19-20　2021

    DOI： 10.11486/ejisso.35.0_17a3-02 　

  41. Effect of Sequential Plasma Activation on Al2O3 for Low Temperature Bonding of Glass Peer-reviewed

    Kai Takeuchi, Tadatomo Suga

    2021 INTERNATIONAL CONFERENCE ON ELECTRONICS PACKAGING (ICEP 2021)　59-60　2021

  42. Surface Activated Bonding of Glass Wafers using Oxide Intermediate Layer Peer-reviewed

    Kai Takeuchi, Fengwen Mu, Yoshiie Matsumoto, Tadatomo Suga

    IEEE 71ST ELECTRONIC COMPONENTS AND TECHNOLOGY CONFERENCE (ECTC 2021)　2024-2029　2021

    DOI： 10.1109/ECTC32696.2021.00319 　

    ISSN： 0569-5503

    eISSN： 2377-5726

  43. Evaluation of Wafer Bond Strength under Vacuum Peer-reviewed

    Kai Takeuchi, Tadatomo Suga

    2021 IEEE CPMT SYMPOSIUM JAPAN (ICSJ)　57-60　2021

    DOI： 10.1109/ICSJ52620.2021.9648866 　

    ISSN： 2373-5449

  44. Surface Activated Bonding of Glass Using Aluminum Oxide Intermediate Layer for Microchannel Fabrication Peer-reviewed

    Kai Takeuchi, Fengwen Mu, Yoshiie Matsumoto, Beomjoon Kim, Tadatomo Suga

    ECS Meeting Abstracts　MA2020-02　(22)　1631-1631　2020/11/23

    Publisher: The Electrochemical Society

    DOI： 10.1149/ma2020-02221631mtgabs 　

    eISSN： 2151-2043

    More details Close

    With a huge demand from the society on a more precise and rapid biological molecule detection in a reduced amount of biosamples, biomedical engineering technology has been in rapid development, resulting in a wide range of biosensors using microfluidic systems. For microfluidic structure, glass is still the main material owing to its chemical stability, cost efficiency, and optical characteristics. In order to seal the fluidic channel based on glass materials, glass substrates should be bonded to cover the channel grooves. Conventionally, glass materials are bonded by anodic bonding or hydrophilic bonding at high temperature process, in which the bonding surfaces are bonded via covalent bonds. However, these bondings of glass at high temperature lead to residual stress at the bonding interface and damage to the device on the substrate, especially the biomolecule sensors using enzymes. In addition to the process temperature, the bonding interface should be transparent as a wide range of biosensors utilizes optical measurements to detect biomarkers. For this reason, a room temperature bonding of glass is desirable for the microchannel sealing. As a room temperature direct bonding method of glass, modified surface activated bonding (mSAB) using Si intermediate layer has been reported to achieve a strong bond of glass via Si layers and Fe nano adhesion layers [1]. Although this approach enables the glass bonding at room temperature, the bonding interface is covered with the deposited Si layers, resulting in deteriorated optical characteristics at the bonding interface. Therefore, mSAB using Si intermediate layer is not suitable for the optical measurement of biomolecules in the microchannels. Recently, we reported a new SAB using aluminum oxide (AlO) intermediate layer instead of Si [2]. AlO has excellent optical characteristics such as low absorbance and refraction index uniformity. From the aspect of bonding, thin AlO membrane by ALD has been reported as intermediate layer for hydrophilic bonding [3]. Furthermore, it has been also reported that bulk sapphire is bonded by standard SAB process, where the sapphire surfaces are activated by Ar ion beam irradiation and bonded through amorphous-like AlO structure [4]. In this study, we apply mSAB using AlO intermediate layer for glass substrate and Si substrate with microchannel patterning. The bonding is evaluated from the perspective of the channel sealing. In order to evaluate the sealing by the proposed bonding method, microfluidic channels were realized on a 4 inch and 525 µm thick Si wafer. The patterning consists of 64x64 inlet ports 100 µm diameter, 46-142 µm wide microchannels, 4x4 mm2 cavity, and capillary pump. For the fabrication of the microfluidic components, inductively coupled plasma reactive ion etching (ICP-RIE) was employed. For the sealing of the microchannels on the Si wafer, mSAB using AlO intermediate layer was conducted. The substrates are activated by Ar ion beam and the AlO layers are deposited by ion beam sputtering, followed by contact and press. After sealing by the wafer bonding, through-glass holes were fabricated by sand blast etching to enable flow in the channels. In order to evaluate the sealing of the microfluidic system by the proposed bonding method, first, scanning acoustic tomography (SAT) was conducted. As shown in Figure, the whole structure is sealed without significant voids. Additionally, we also evaluated the sealing of the microfluidic structure by a flow test. A droplet of phosphate buffered-saline (PBS) as a model liquid of biosample was put on the inlet ports. As a result, PBS flow was observed through the microchannels and capillary pump without leakage. Therefore, it can be said that the proposed bonding method successfully sealed the microfluidic system and the bonding interface kept its transparency. From these result, it is indicated that the developed bonding method is suitable for the microchannel device fabrication by realizing a transparent bonding interface at room temperature. MMR Howlader, S. Suehara, and T. Suga. Sensors and Actuators A: Physical, 127(1):31–36, 2006. Takeuchi, F. Mu, Y. Matsumoto and T. Suga, 6th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D), Kanazawa, Japan, 2019, pp. 85-85. Ikku, M. Yokoyama, R. Iida, M. Sugiyama, Y. Nakano, M. Takenaka, and S. Takagi, 23rd International Conference on Indium Phosphide and Related Materials, May 2011, pp. 1–4. Takagi, Y. Kurashima, A. Takamizawa, T. Ikegami, and S. Yanagimachi, Jpn. J. Appl. Phys., Vol. 57, 02BA04, 2017. Figure 1 <p></p>

  45. Porous Microneedle Integrated in Paper based Glucose Sensor for Fluid Channel Interface Peer-reviewed

    Hakjae Lee, Kai Takeuchi, Yui Sasaki, Nobuyuki Takama, Tsuyoshi Minami, Beomjoon Kim

    2019 IEEE CPMT Symposium Japan (ICSJ)　39-42　2019/11

    DOI： 10.1109/icsj47124.2019.8998695 　

    ISSN： 2373-5449

  46. Capillary driven porous pdms microneedle for naked-eye glucose sensor

    Hakjae Lee, Kai Takeuchi, Yui Sasaki, Nobuyuki Takama, Tsuyoshi Minami, Beomjoon Kim

    23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019　654-656　2019

  47. Room Temperature Bonding of Quartz Glass using Aluminum Oxide Intermediate Layer Peer-reviewed

    Kai Takeuchi, Fengwen Mu, Yoshiie Matsumoto, Tadatomo Suga

    PROCEEDINGS OF 2019 6TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE BONDING FOR 3D INTEGRATION (LTB-3D)　85-85　2019

    DOI： 10.23919/ltb-3d.2019.8735327 　

  48. Correction to: Functionalized microneedles for continuous glucose monitoring (Nano Convergence, (2018), 5, 1, (28), 10.1186/s40580-018-0161-2)

    Kai Takeuchi, Beomjoon Kim

    Nano Convergence　5　(1)　2018/12/01

    Publisher: Korea Nano Technology Research Society

    DOI： 10.1186/s40580-018-0169-7 　

    ISSN： 2196-5404

  49. Functionalized microneedles for continuous glucose monitoring Peer-reviewed

    Kai Takeuchi, Beomjoon Kim

    Nano Convergence　5　(1)　2018/12

    DOI： 10.1186/s40580-018-0161-2 　

    ISSN： 2196-5404

    eISSN： 2196-5404

  50. Mechanism of bonding and debonding using surface activated bonding method with Si intermediate layer Peer-reviewed

    Kai Takeuchi, Masahisa Fujino, Yoshiie Matsumoto, Tadatomo Suga

    JAPANESE JOURNAL OF APPLIED PHYSICS　57　(4)　2018/04

    DOI： 10.7567/JJAP.57.04FC11 　

    ISSN： 0021-4922

    eISSN： 1347-4065

  51. Room temperature bonding and debonding of polyimide film and glass substrate based on surface activate bonding method Peer-reviewed

    Takeuchi Kai, Fujino Masahisa, Matsumoto Yoshiie, Suga Tadatomo

    Japanese Journal of Applied Physics　57　(2)　02BB05-02BB05　2018/01/15

    DOI： 10.7567/jjap.57.02bb05 　

    ISSN： 0021-4922

    eISSN： 1347-4065

  52. A Porous Microneedle Array Connected to Microfluidic System for ISF Collection Peer-reviewed

    Kai Takeuchi, Nobuyuki Takama, Beomjoon Kim, Kirti Sharma, Patrick Ruther, Oliver Paul

    2018 IEEE CPMT SYMPOSIUM JAPAN (ICSJ)　85-88　2018

    DOI： 10.1109/icsj.2018.8602945 　

    ISSN： 2373-5449

  53. Room Temperature Temporary Bonding of Glass Substrates Based on SAB Method Using Si Intermediate Layer Peer-reviewed

    Kai Takeuchi, Masahisa Fujino, Tadatomo Suga

    IEEE TRANSACTIONS ON COMPONENTS PACKAGING AND MANUFACTURING TECHNOLOGY　7　(10)　1713-1720　2017/10

    DOI： 10.1109/TCPMT.2017.2731621 　

    ISSN： 2156-3950

    eISSN： 2156-3985

  54. Bonding and Debonding of Si/Glass based on SAB Method Combined with Hydrophilic Treatment Peer-reviewed

    K. Takeuchi, Y. Matsumoto, T. Suga

    Extended Abstracts of the 2017 International Conference on Solid State Devices and Materials　2017/09/21

    Publisher: The Japan Society of Applied Physics

    DOI： 10.7567/ssdm.2017.h-4-04 　

  55. Room temperature bonding and debonding of PI film and glass substrate based on SAB method Peer-reviewed

    K. Takeuchi, M. Fujino, Y. Matsumoto, T. Suga

    2017 5th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)　2017/05

    Publisher: IEEE

    DOI： 10.23919/ltb-3d.2017.7947434 　

  56. Modified Surface Activated Bonding Using Si Intermediate Layer for Bonding and Debonding of Glass Substrates Peer-reviewed

    K. Takeuchi, M. Fujino, T. Suga

    ECS Transactions　75　(9)　185-189　2016/09/23

    Publisher: The Electrochemical Society

    DOI： 10.1149/07509.0185ecst 　

    ISSN： 1938-6737

    eISSN： 1938-5862

  57. Direct Bonding and Debonding of Glass Wafers for Handling of Ultra-thin Glass Sheets Peer-reviewed

    Kai Takeuchi, Masahisa Fujino, Tadatomo Suga

    2016 International Conference on Electronics Packaging (ICEP)　298-301　2016

  58. Room Temperature Bonding and Debonding of Ultra-Thin Glass Substrates for Fabrication of LCD Peer-reviewed

    Kai Takeuchi, Masahisa Fujino, Tadatomo Suga

    2016 IEEE 66TH ELECTRONIC COMPONENTS AND TECHNOLOGY CONFERENCE (ECTC)　1284-1289　2016

    DOI： 10.1109/ECTC.2016.145 　

    ISSN： 0569-5503

  59. Room temperature direct bonding and debonding of polymer film on glass wafer for fabrication of flexible electronic devices Peer-reviewed

    K. Takeuchi, M. Fujino, T. Suga, M. Koizumi, T. Someya

    2015 IEEE 65th Electronic Components and Technology Conference (ECTC)　2015/05

    Publisher: IEEE

    DOI： 10.1109/ectc.2015.7159668 　

  60. Room temperature direct bonding and debonding of polyimide film on glass wafer using Si intermediate layer Peer-reviewed

    K. Takeuchi, M. Fujino, T. Suga, M. Koizumi, T. Someya

    2015 International Conference on Electronic Packaging and iMAPS All Asia Conference (ICEP-IAAC)　2015/04

    Publisher: IEEE

    DOI： 10.1109/icep-iaac.2015.7111037 　

Show all ︎Show first 5

Misc. 27

  1. 水中貼り合わせにおけるポリシラザン接合界面のシリカ転化進行の分析—Analysis of Polysilazane-to-Silica Conversion at the Interface Formed by Bonding in Water—第17回集積化MEMSシンポジウム

    根本 大輝, 竹内 魁, 日暮 栄治

    「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編]　42　3p　2025/11

    Publisher: [東京] : Institute of Electrical Engineers of Japan

  2. 金薄膜転写による金めっき膜平滑化における転写膜厚と転写性—Thickness dependence of transferability in plated Au surface smoothing based on template-stripping

    小関 奨吾, 後藤 慎太郎, 竹内 魁, 日暮 栄治, レ ハクホウントゥー, 松前 貴司, 高木 秀樹, 倉島 優一, 津田 貴大, 清水 寿和, 徳久 智明

    「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編]　42　4p　2025/11

    Publisher: [東京] : Institute of Electrical Engineers of Japan

  3. Au-Au常温接合を可能にするVUV光を用いた表面活性化条件の検討—Investigation of surface activation conditions using VUV light to enable room-temperature Au-Au bonding

    荻野 美佳, 竹内 魁, 日暮 栄治

    「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編]　42　5p　2025/11

    Publisher: [東京] : Institute of Electrical Engineers of Japan

  4. 常温接合をめざした研磨を必要としない表面平滑化技術

    日暮栄治, 竹内魁

    月刊機能材料　45　(9)　3　2025/09

  5. Effect of high-temperature heat treatment on the microstructure and mechanical strength of Au-Au room-temperature bonded interfaces

    石岡弘成, 竹内魁, 日暮栄治

    マイクロエレクトロニクスシンポジウム論文集　35th　2025

    ISSN： 2434-396X

  6. Adhesion of Si and LiNbO3 via Perhydropolysilazane for Photonic Substrate Fabrication

    菱沼景, 竹内魁, 日暮栄治

    エレクトロニクス実装学会春季講演大会論文集　39th　2025

  7. Surface smoothing of plated Au bumps based on Template-stripping for low-temperature bonding

    小関奨吾, 後藤慎太郎, 竹内魁, THU Le Hac Huong, 松前貴司, 高木秀樹, 倉島優一, 津田貴大, 清水寿和, 徳久智明, 日暮栄治

    エレクトロニクス実装学会春季講演大会論文集　39th　2025

  8. Au薄膜転写により平滑化したAlNセラミック基板の表面活性化常温接合

    後藤慎太郎, 小関奨吾, 竹内魁, 日暮栄治

    エレクトロニクス実装学会春季講演大会論文集　39th　2025

  9. Fabrication of hollow micro-bump arrays by Au thin film transfer

    後藤慎太郎, 竹内魁, 日暮栄治, LE Hac Huong Thu, 松前貴司, 高木秀樹, 倉島優一

    センサ・マイクロマシンと応用システムシンポジウム(CD-ROM)　41st　2024

  10. Room-temperature bonding of wafers with Au thin films using sequential surface treatment by VUV light and Ar plasma

    荻野美佳, 竹内魁, 日暮栄治

    センサ・マイクロマシンと応用システムシンポジウム(CD-ROM)　41st　2024

  11. Adhesion between Si Substrates in Liquid using Polymeric Precursor of SiO2

    根本大輝, 竹内魁, 日暮栄治

    センサ・マイクロマシンと応用システムシンポジウム(CD-ROM)　41st　2024

  12. Wafer bonding via Perhydropolysilazane at room temperature

    竹内魁, 根本大輝, 日暮栄治

    センサ・マイクロマシンと応用システムシンポジウム(CD-ROM)　41st　2024

  13. Au flat micro-bump arrays fabricated by transfer and coining of Au thin films

    後藤慎太郎, 竹内魁, LE Hac Huong Thu, 松前貴司, 高木秀樹, 倉島優一, 日暮栄治

    マイクロエレクトロニクスシンポジウム論文集　34th　2024

    ISSN： 2434-396X

  14. Surface smoothing of Au plated films by template stripping using polyimide films

    小関奨吾, 荻野美佳, 竹内魁, LE Hac Huong Thu, 松前貴司, 高木秀樹, 倉島優一, 津田貴大, 清水寿和, 徳久智明, 日暮栄治

    エレクトロニクス実装学会講演大会講演論文集(CD-ROM)　38th　2024

    ISSN： 1880-4616

  15. Effect of Water on Wafer Bonding Interface

    Kai Takeuchi

    Journal of The Japan Institute of Electronics Packaging　26　(5)　434-440　2023/08/01

    Publisher: Japan Institute of Electronics Packaging

    DOI： 10.5104/jiep.26.434 　

    ISSN： 1343-9677

    eISSN： 1884-121X

  16. Passivation of Activated Au Surface for Low Temperature Bonding

    竹内魁, 日暮栄治, KIM Beomjoon, WANG Junsha, 須賀唯知

    センサ・マイクロマシンと応用システムシンポジウム(CD-ROM)　40th　2023

  17. 2nd quantized state oscillation in a gain switched 925nm-band QW-LD and its suppression

    古戸颯真, CUI Yuwen, 竹内魁, 山田博仁, 横山弘之, 日暮栄治

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)　84th　2023

    ISSN： 2758-4704

  18. Progress and future perspective of room-temperature bonding technologies for heterogeneous integration

    日暮栄治, 竹内魁

    電子情報通信学会技術研究報告(Web)　123　(142(CPM2023 10-22))　2023

    ISSN： 2432-6380

  19. Second-quantized-state laser oscillation dynamics of a 925nm-band QW-LD under strong pulsed excitation

    CUI Y., 安食聡一郎, 竹内魁, 竹内魁, 日暮栄治, 日暮栄治, 山田博仁, 山田博仁, 山田博仁, 横山弘之, 横山弘之

    応用物理学会春季学術講演会講演予稿集(CD-ROM)　70th　2023

    ISSN： 2436-7613

  20. GaN/カーボン材料の低熱抵抗界面を目的としたAu低温接合

    竹内 魁, 須賀 唯知, 田中 敦之, 分島 彰男

    精密工学会学術講演会講演論文集　2021S　699-700　2021/03/03

    Publisher: 公益社団法人 精密工学会

    DOI： 10.11522/pscjspe.2021s.0_699 　

    More details Close

    GaNを用いたパワーデバイスの実装では、効率の良い放熱のためにカーボン材料をGaNに接合する必要がある。その際カーボン材料の表面粗さやGaNデバイスへのダメージ低減のため、接合荷重や接合温度に制限が生じる。本研究では、Ar原子ビームによって活性化した Au薄膜を介することで、GaN/カーボン材料の150°Cでの大気中接合を達成した。

  21. アルミシリケートガラスの低温接合のためのシーケンシャルプラズマ活性化のAl2O3への影響

    竹内 魁, 須賀 唯知

    エレクトロニクス実装学術講演大会講演論文集　35　18C4-05　2021

    Publisher: 一般社団法人エレクトロニクス実装学会

    DOI： 10.11486/ejisso.35.0_18c4-05 　

  22. 表面活性化によるGaN/カーボン材のAu層を介した低温接合

    竹内 魁, 須賀 唯知, 田中 敦之, 分島 彰男

    エレクトロニクス実装学術講演大会講演論文集　35　17A3-03　2021

    Publisher: 一般社団法人エレクトロニクス実装学会

    DOI： 10.11486/ejisso.35.0_17a3-03 　

  23. SiC/Ni中間層を用いたGaN基板の常温接合

    竹内 魁, 須賀 唯知, Mu Fengwen, 魚本 幸, 島津 武仁

    エレクトロニクス実装学術講演大会講演論文集　35　17A3-04　2021

    Publisher: 一般社団法人エレクトロニクス実装学会

    DOI： 10.11486/ejisso.35.0_17a3-04 　

  24. 表面活性化による異種材料接合と界面形成—Bonding and Interfaces of Dissimilar Materials by Means of Surface Activation Method—特集 セラミックスコーティングの新潮流 : 界面制御が拓く新しい機能

    須賀 唯知, 竹内 魁

    Ceramics Japan = セラミックス : bulletin of the Ceramic Society of Japan　55　(10)　716-719　2020/10

    Publisher: 日本セラミックス協会

    ISSN： 0009-031X

  25. Functionalized microneedles for continuous glucose monitoring

    Kai Takeuchi, Beomjoon Kim

    NANO CONVERGENCE　5　2018/10

    DOI： 10.1186/s40580-018-0161-2 　

    ISSN： 2196-5404

  26. Fabrication of biodegradable porous microneedle

    Morishita Yasuhisa, Takeuchi Kai, Takama Nobuyuki, Kim Beomjoon

    Proceedings of JSPE Semestrial Meeting　2018　734-735　2018

    Publisher: The Japan Society for Precision Engineering

    DOI： 10.11522/pscjspe.2018A.0_734 　

  27. Direct Bonding and Debonding of PI film and Glass Wafer using Si intermediate layer for TFT fabrication

    Proceedings of JIEP Annual Meeting　29　537-540　2015

    Publisher: The Japan Institute of Electronics Packaging

    DOI： 10.11486/ejisso.29.0_537 　

Show all ︎Show first 5

Books and Other Publications 1

  1. 3D半導体実装技術

    福島, 誉史, 清山 浩司, 橋本 宏之, 岡谷 貴之, 堀尾 喜彦, 田中 徹, 小柳 光正, 仮屋 和浩, 松澤 浩彦, 山本 孝, 宮下 準弘, 楠田 豊, 小寺 雅子, 岩佐 毅彦, 畠井 宗宏, 喜多 直紀, 佐波 正浩, 八甫谷 明彦, 竹内 魁, 晴 孝志, 三ッ石 創, 張 秉得, 西田 秀行, 亀和田 忠司, 大井 淳, 中辻 達也, 川野 連也, 岩元 勇人, 田上 政由, 河原 尊之, 野村 和宏, 牧原 康二, 田中 祐介, 斉藤 高志, 七呂 真, 中村 悠介, 髙橋 将友, 高木 剛, 木野 久志, 亀山 修一, 山中 公博

    エヌ・ティー・エス　2025/10

    ISBN: 9784860439880

Presentations 4

  1. Polysilazane-induced Wafer Bonding at Room Temperature and its Characteristics Invited

    Kai Takeuchi

    International Microsystems, Packaging, Assembly and Circuits Technology Conference　2025/08/22

  2. Polysilazane-Mediated Room Temperature Bonding for Electronics Packaging Invited

    Kai Takeuchi

    27th International Conference on Electronic Packaging Technology　2025/08/07

  3. Spontaneous formation of SiO2 bonding interface via polysilazane conversion Invited

    Kai Takeuchi

    International Workshop on Low Temperature Bonding for 3D Integration　2025/08/03

  4. ヘテロジニアス集積に向けた常温接合技術の動向と今後の展開 Invited

    日暮 栄治, 竹内 魁

    信学技報　2023

Research Projects 4

  1. Creation of fundamental technology on room-temperature bonding through nano-interface control

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2024/04/01 - 2026/03/31

  2. 常温接合技術に基づく耐腐食性接合界面の創出

    竹内 魁

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 若手研究

    Category: 若手研究

    Institution: 東北大学

    2023/04 - 2026/03

  3. 高出力用光学素子実装のための直接接合技術の開発

    竹内魁

    Offer Organization: 公益財団法人 天田財団

    System: 奨励研究助成（若手研究者枠）

    Institution: 明星大学

    2021/10 - 2024/03

  4. 光学素子実装のための酸化アルミニウム中間層を介したガラス材料の常温透明接合

    竹内魁

    Offer Organization: 公益財団法人 精密測定技術振興財団

    System: 研究助成

    Category: 助成金

    Institution: 明星大学

    2021/04 - 2022/03

Teaching Experience 2

  1. 学生実験A　東北大学

  2. 学生実験D　東北大学