【公開日：2025.06.10】【最終更新日：2025.05.16】
課題データ / Project Data
課題番号 / Project Issue Number
24JI1036
利用課題名 / Title
電子部品用プリント基板材料における絶縁樹脂と金属膜の界面の評価
利用した実施機関 / Support Institute
北陸先端科学技術大学院大学 / JAIST
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）マルチマテリアル化技術・次世代高分子マテリアル/Multi-material technologies / Next-generation high-molecular materials
キーワード / Keywords
電子顕微鏡/ Electronic microscope,イオンミリング/ Ion milling,電子回折/ Electron diffraction,PVD,スパッタリング/ Sputtering,膜加工・エッチング/ Film processing/etching,エレクトロデバイス/ Electronic device,チップレット/ Chiplet,異種材料接着・接合技術/ Dissimilar material adhesion/bonding technology
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)
遠藤 真一
所属名 / Affiliation
ウシオ電機株式会社
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
東嶺孝一
利用形態 / Support Type
（主 / Main）技術代行/Technology Substitution（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)
In this work, pretreatment with vacuum ultraviolet (VUV) light changed the adhesion strength between an epoxy resin and directly sputtered copper in a printed circuit board manufacturing process. The adhesion strength was 0.9 N/cm without irradiation but had a peak value of 2.1 N/cm at 540 mJ/cm2 of VUV irradiation; with increasing VUV irradiation, the adhesion strength decreased. Based on x-ray photoelectron spectroscopy (XPS) analysis of the copper interface of copper peeled from the resin, we evaluated the abundance ratio of metallic and organic oxygen at interfaces exposed to different VUV irradiation doses. We found that the change in the abundance ratio of metallic and organic oxygen was similar to the change in adhesion strength between copper and epoxy resin after exposure to different VUV irradiation doses. We observed the interface between copper and resin via scanning transmission electron microscopy (STEM) and found a distributed layer of oxygen. The functional group concentration in STEM images suggested the presence of a material with an intermediate density. We used chemically modified XPS to evaluate changes in the functional group concentration on epoxy resin surfaces irradiated with VUV light. We found that the hydroxyl group (OH) formed by VUV irradiation and the copper formed by direct sputtering improved adhesion strength in a synergistic manner. We observed a correlation between OH concentration on the resin surface and adhesion strength. These results will help to optimize the VUV irradiation process for adhesion between epoxy resin and sputtered copper.
実験 / Experimental
(Only STEM evaluation)Scanning Transmission Electron Microscopy (STEM) Observation of Interface We used STEM and energy-dispersive x-ray spectrometry (EDS) to investigate the structure and chemical elements of the copper-dielectric resin interface. The surface of the sample was coated with carbon and palladium–platinum using an ion sputtering device (E-1030, Hitachi High-Tech Corporation, Tokyo, Japan). The carbon coating conditions were as follows; pressure of 6 Pa, load current of 20 A, vapor deposition time of 10 s, and thickness of 10 nm; the palladium–platinum coating conditions were as follows; pressure of 6 Pa, discharge current of 15 mA, discharge time of prepared with a gallium ion source at an accelerating voltage of 30 kV. High-angle annular dark-field (HAADF) observations of the interface of a thin-section sample were performed using a scanning transmission electron microscope (JEMARM200F, JEOL Co. Ltd., Tokyo, Japan). The STEM imaging conditions were as follows: convergence angle, 24 mrad; HAADF collection angle, 67-250 mrad; bright field (BF), 15 mrad. The distribution of copper, oxygen, carbon, and silicon at the interface was confirmed by line and area analysis images obtained from EDS. 400 s, and thickness of 40 nm. A tungsten protective layer was deposited for slimming of the sample using a focused ion beam. The formation area was 25 × 2.5 μm2, the pressure was 2 × 10−3 Pa, the current was 300 pA, the deposition time was 26 min, and the film thickness was 600 nm. Figure 4 illustrates a method for collecting a STEM sample from an epoxy resin sample sputtered with copper. The red arrow in the figure indicates the observation direction of the cross section of the interface. Using a focused ion beam device (SMI3050, Seiko Instruments Inc., Chiba, Japan), a cross-sectional thin-section sample of the interface with a thickness of ~100 nm was
結果と考察 / Results and Discussion
To investigate the state of the interface after sputtering, we observed a cross-section of the interface by STEM. Figure 10 shows STEM BF images of the interface: (a)×200,000 magnification, (b) ×2,000,000 magnification, (c) ×8,000,000 magnification. The top left portion of Fig. 10a shows the dielectric resin, and the bottom right portion shows the copper sputter film side. The sputtering thickness was 300 nm, and grainy substances were observed at the interface. Figure 10b shows a magnified image of the interface, in which the particulate matter has an intermediate concentration and is 10–20 nm in size. Figure 10c shows a magnified image of the granular material, which exhibits some regular patterns. The results presented in Fig. 10a to c indicate that a crystalline substance at the interface differs from the dielectric resin and copper. Figure 11 shows HAADF-STEM and EDS images. In (a), the light area on the left represents copper and the dark area on the right represents the dielectric resin. In the STEMHAADF image (a), streak-like dark areas are observed in the horizontal direction in the copper region, and the streak-like contrast can be attributed to a density difference caused by the column-shaped growth of the sputtered copper layer. A moderately dense oxygen layer with a thickness of several tens of nanometers was observed at the interface between the copper and the epoxy resin. Elemental analysis using EDS in the observation area of HAADF image (a) using STEM reveals copper, oxygen, carbon, and silicon. Elemental mapping images by EDS show (b) copper, (c) oxygen, (d)carbon, and (e) silicon. Figure 11c shows that oxygen is distributed at the interface. The rounded areas in the EDS mapping images (Fig. 11c and d) represent silica filler (SiO2). Figure 12a shows the linear density analysis of carbon, oxygen, and silicon at the interface of a sample irradiated with 540 mJ/cm2 of VUV irradiation. Figure 12b shows the linear density analysis results for carbon, oxygen, and silicon at the interface of a non-irradiated sample. Comparisons with the background HAADF image indicated the presence or absence of an intermediate concentration layer at the interface. The center line of the rectangle in the image indicates the position of the line analysis; the top and bottom lines indicate the width of the analysis area. The oxygen density peaked at the interface as shown in Fig. 12a. The scale bar in Fig. 12a indicates the presence of oxygen in a ~60-nm-wide band at the interface. This oxygen band overlapped with the intermediate concentration layer at the interface, suggesting that it existed as a copper oxide. Cross-sectional analysis of the interface using STEM and EDS in Figs. 10, 11, and 12 reveals the presence of material representing an intermediate density layer between the copper and resin. EDS mapping detected a 60-nm-thick oxygen layer, suggesting that copper sputtering and VUV irradiation formed oxides at this depth.
図・表・数式 / Figures, Tables and Equations
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
Acknowledgments This research was supported in part by the Advanced Materials Research Infrastructure Project (ARIM) of the Ministry of Education, Culture, Sports, Science and Technology (Project # JPMXP1222JI051), to whom we express our gratitude. The authors acknowledge Mayumi ITO (JAIST) for preparation of the cross-sectional TEM samples.
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)
-
Shinichi Endo, Effect of Hydroxyl Group Concentration Generated by Vacuum Ultraviolet Light on the Adhesion Between Epoxy Resin and Copper, Journal of Electronic Materials, 53, 7044-7056(2024).
DOI: https://doi.org/10.1007/s11664-024-11379-0
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：3件
特許登録件数 / Number of Registered Patents：0件