【公開日：2025.06.10】【最終更新日：2025.04.30】
課題データ / Project Data
課題番号 / Project Issue Number
24UT1084
利用課題名 / Title
実装工学における接合技術開発
利用した実施機関 / Support Institute
東京大学 / Tokyo Univ.
機関外・機関内の利用 / External or Internal Use
外部利用/External Use
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）加工・デバイスプロセス/Nanofabrication
【重要技術領域 / Important Technology Area】（主 / Main）高度なデバイス機能の発現を可能とするマテリアル/Materials allowing high-level device functions to be performed（副 / Sub）-
キーワード / Keywords
高周波デバイス/ High frequency device,ハイブリッドボンディング/ Hybrid Bonding,高品質プロセス材料/技術/ High quality process materials/technique,走査プローブ顕微鏡/ Scanning probe microscope,ボンディング/ Bonding
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
須賀 唯知
所属名 / Affiliation
一般社団法人電子実装工学研究所
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
王 俊沙,清水 彩和子
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
利用形態 / Support Type
（主 / Main）機器利用/Equipment Utilization（副 / Sub）-
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
Thermal management is critically important for system integration, especially for 3D integration. Due to the high thermal conductivity and high elastic modulus of diamond, direct bonding of diamond wafers and other wafers has long been expected to be a technology that will solve the heat dissipation problem of power devices and open the possibility of developing new surface acoustic wave devices. However, conventional bonding technologies require high-temperature process, and the direct bonding of diamonds and semiconductors until now has only been possible with small pieces. To solve the warpage and surface roughness problems of diamond wafers and realize the bonding between diamond wafers and other substrates, the authors innovatively proposed a new polishing method combining a plasma-assisted polishing (PAP) process and a dry etching process using gas cluster ion beam (GCIB).
実験 / Experimental
The 2-inch polycrystalline diamond wafers used in this experiment were grown on Si substrates. The as-grown diamond wafers were first polished by CMP. Then, PAP was used to decrease the curvature (sori) of the wafers. Finally, GCIB was applied for the final surface smoothing. To trace the surface roughness of diamond wafers at different stages, a atomic force microscopy (AFM, L-trace II) was used.
結果と考察 / Results and Discussion
The AFM image of diamond surface after CMP is
displayed in Fig. 1. Due to the anisotropy of diamond polishing, diamond grains
with the " hard " orientation was difficult to be smoothed resulting
in protrusions left on the surface. The height of large protrusions was about
20 nm, and that of small ones was about 10 nm. General speaking, the surface
without diamond grain protrusions was smooth. From the AFM image of PAP
processed diamond in Fig. 2, it is noted that although the diamond protrusions
disappeared, the surface was not smooth enough with the Ra 2.4 nm and RMS 3.2
nm. To obtain the atomic smooth surface, SF6-GCIB was applied to irradiate the
diamond wafer. The AFM image of in Fig. 3 shows that the polishing lines on
diamond surface was removed resulting in a ultra smooth surface with the
surface roughness Ra of 0.4 nm and RMS of 0.5 nm, which could meet the
requirement of direct bonding.
Diamond wafers after the final GCIB polishing
were bonded to LiNbO3 wafer and GaN wafer using the modified SAB with Si
nano-adhesion layer. The images of bonded wafers present in Fig. 4 verify that
the whole area bonding was achieved except the edge and particle existed areas.
図・表・数式 / Figures, Tables and Equations
Fig.1 AFM image of diamond wafer surface after CMP.
Fig.2 AFM image of diamond wafer surface after PAP.
Fig.3 AFM image of diamond wafer surface after SF6 GCIB.
Fig.4 Images of bonded wafers (a) 2 inch diamond wafer/ 4inch LiNbO3 wafer; (b) 2 inch diamond/ 2 inch GaN wafer.
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
-
Tadatomo Suga, Room Temperature Bonding of CVD Polycrystalline Diamond Wafers to Semiconductor and Piezo-electric Single Crystalline Wafers, 2024 IEEE 74th Electronic Components and Technology Conference (ECTC), , 353-356(2024).
DOI: 10.1109/ECTC51529.2024.00319
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
- 大口径ダイヤモンドウエハの超平滑化加工と常温接合, ニューダイヤモンド, 第156号, Vol. 41, No.1, pp. 36-371, 2025年1月25日発行
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件