【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
24UT1030
利用課題名 / Title
ハイブリッド接合
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）-
【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
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
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)
黒田 忠広
所属名 / Affiliation
先端システム技術研究組合
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
Wang Junsha
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)
Hybrid bonding is a direct bonding process where two hybrid surfaces made of planarized dielectric SiO2 surrounding isolated Cu vias are bonded together. SiO2 is bonded by hydrophilic bonding, while Cu is bonded by diffusion bonding or even just contact. Due to the native oxide of Cu, the commonly used bonding temperature is around 350 °C, which is too high for some thermal-sensitive devices. Therefore, we propose Cu/Cu hydrophilic bonding at 200 °C. Cu wafers are sensitive to the environment and can be oxidized easily. Therefore, the effect of the storage atmosphere and duration on the surface roughness was investigated. To remove the native oxide, the ion beam was adopted. and the etching rate of Cu by Ar or N2 ion beam was attempted to be measured.
実験 / Experimental
4-inch Si wafers were used as substrates, and then a 25 nm-thick Ti film followed by a 1 um-thick Cu film were sputtered. Subsequently, the Cu surface was smoothed by chemical mechanical polishing (CMP). Finally, the Cu wafers were stored in air or sealed plastic bags for 3 months without any preservation treatments, and then the surface roughness of Cu wafers was measured by a dynamic force microscopy (DFM, L-trace II). To investigate the etching rate of Cu by ion beams, the Cu wafers were covered with glass mask and only the center parts were irradiated by Ar or N2 ion beam. After irradiation, the profile of etched area and un-etched area was characterized by a stylus profiler (Dektak XT-S).
結果と考察 / Results and Discussion
(1) The
effect of storage atmosphere on surface roughness.
After
CMP, the surface roughness of the Cu wafer was Ra 0.3 nm/ Rq 0.3 nm (as shown
in Fig. 1). After being stored in air for 2 months or sealed plastic bags for 3
months, the roughness of Cu increased to Ra 0.5 nm/ RMS 0.9 nm and Ra 1.3 nm/
RMS 1.5 nm, respectively. Especially when Cu wafers were kept in air, the
surface morphology changed greatly due to severe oxidation. In conclusion, the
storage atmosphere has significant effects on the surface condition of Cu
wafers.
(2) The
uniformity of Cu wafer surface.
Before
bonding experiments, the center and edge of Cu wafers were measured by DFM. Due
to surface oxidation, the surface roughness of Cu increased. However, no
significant differences were observed between the wafer center and wafer edge
(as shown in Fig. 2).
(3) The
etching rate of Cu by ion beam.
The warpage of Cu wafers
was around 20 µm, but the etch depth was predicted to be ～100 nm or less. When
the profile of the irradiated area and un-irradiated area was measured, the etch
depth was too small to be observed in the measured profile. Consequently, the
etching rate of Cu by ion beam failed to be measured by Dektak.
図・表・数式 / Figures, Tables and Equations
Fig. 1 The surface roughness of Cu wafers after being stored under different conditions
Fig. 2 The surface roughness of the Cu wafer center and edge
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
This work is supported by New Energy and Industrial Technology Development Organization (NEDO), Japan (JPNP20017).
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)
-
J. Wang, Investigation of Low Temperature Cu/Cu Wafer Bonding for Hybrid Bonding Applications, 2024 8th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D), , 1-1(2024).
DOI: 10.1109/LTB-3D64053.2024.10774086
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