【公開日：2024.07.25】【最終更新日：2024.05.17】

課題データ / Project Data

課題番号 / Project Issue Number

23UT1054

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）加工・デバイスプロセス/Nanofabrication（副 / Sub）計測・分析/Advanced Characterization

【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

走査プローブ顕微鏡/ Scanning probe microscope,光デバイス/ Optical Device,ボンディング/ Bonding,チップレット/ Chiplet,ハイブリッドボンディング/ Hybrid 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

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

UT-850：形状・膜厚・電気特性評価装置群
UT-861：走査型プローブ顕微鏡

報告書データ / Report

概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)

Due to the high thermal conductivity and high elastic modulus, diamond is the ideal heat sink material to solve the heat dissipation problem. However, how to realize diamond polishing for direct bonding with high efficiency and less damage is a big issue. We propose to polish CVD diamond by gas cluster ion beam (GCIB), and the effects of gas variety on the diamond removal thickness and surface roughness were discussed.

実験 / Experimental

CVD single crystal (100)-oriented diamond chips with the size of 10 x 10 mm² were used in this study. Before GCIB irradiation, diamond chips were well-polished by CMP, and the Ra was below 1 nm. Ar and SF₆ were chosen as the source gas. After irradiation, the etched thickness and the surface roughness of diamond were characterized by a stylus profiler (Dektak XT-S) and a dynamic force microscopy (DFM, L-trace II), respectively. 

結果と考察 / Results and Discussion

To compare the removed thickness of diamond irradiated by Ar-GCIB and SF₆-GCIB, the ion dose and acceleration voltage were fixed to 1 x 10¹⁷ ions/cm² and 30 keV, respectively. As shown in Fig. 1, the removed thickness of diamond by Ar-GCIB and SF₆-GCIB irradiation was 330 nm and 470 nm, respectively. When Ar cluster impacts diamond surface, only physical sputtering happened. While SF₆ cluster collides the diamond, the dissociations of SF₆ cluster and SF₆ molecule itself take place at the same time. Dissociated fluorine reacts with carbon atoms and generates volatile material as CF₄. This reactive sputtering will increase the number of sputtered carbon atoms resulting in high removal rate of diamond. It demonstrates that the reactive gas will produce higher etching rate than the inert gas.    Fig. 2 shows the surface roughness of diamond after irradiated by Ar-GCIB and SF₆-GCIB with the ion dose of 1 x 10¹⁷ ions/cm² and the acceleration voltage of 30 keV. As seen in Fig. 2 (b), ripples on diamond surface were removed by Ar cluster, but the smooth surface was roughed from Ra 0.5 nm to Ra 2.8 nm. It was quite different from the smoothing of an rough polycrystalline diamond surface, where Ar-GCIB could change the diamond morphology and at the same time decrease the surface roughness. While after SF₆-GCIB irradiation, ripples still existed on diamond surface and the surface roughness decreased slightly. This is consistent with the case of an rough polycrystalline diamond polishing.    The influence of ion dose of SF₆-GCIB on the diamond surface roughness at 90 μm x 90 μm was recorded in Fig. 3. Both the Ra and RMS reduced with the growing ion dose, and the most smooth surface polished by SF₆-GCIB at present was Ra 0.6 nm/RMS 0.7nm. 

図・表・数式 / Figures, Tables and Equations

Fig. 1 Removed thickness of diamond by GCIB with the ion dose of 1 x 10¹⁷ ions/cm² and the acceleration voltage of 30 ekV. (a) Ar-GCIB irradiation, (b) SF₆-GCIB irradiation.

Fig. 2 AFM images of diamond surface irradiated by Ar-GCIB and SF₆-GCIB with the ion dose of 1 x 10¹⁷ ions/cm² and the acceleration voltage of 30 keV

Fig. 3 The surface roughness of diamond at 90 μm x 90 μm after irradiated by SF₆-GCIB with different ion dose.

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)

1. Junsha Wang, Polishing of CVD Diamond for Direct Bonding Using Ar and SF6-Gas Cluster Ion Beams, 2023 IEEE CPMT Symposium Japan (ICSJ), , 17-20(2023).
   DOI: 10.1109/ICSJ59341.2023.10339595
   

口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.

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