报告时间：2018年7月31日（星期二）9:30-11:00
报告地点：翡翠湖校区科教楼A座一楼第五会议室
报告人：Prof. Tadatomo Suga
工作单位: The Department of Precision Engineering, The University of Tokyo
举办单位：电子科学与应用物理学院
报告人简介：
Tadatomo SUGA joined the Max‐Planck Institut für Metallforschung in 1979, and received the Ph.D. degree in materials science from University of Stuttgart in 1983. Since 1984 he has been a faculty member of the University of Tokyo, and since 1993, he has been a professor at the Department of Precision Engineering of the School of Engineering. He was also the director of Research Group of Interconnect Ecodesign at National Institute of Materials Science (NIMS), and a Member of Japan Council of Science, as well as the chair of IEEE CPMT Society Japan Chapter. His researches focus on micro‐systems integration and packaging, and development of interconnect technology, especially the room temperature bonding technique for 3D integration.
He has endeavored to establish collaboration between industries and academia for the packaging technology, directing R&D project of the Institute of Micro‐System Integration (IMSI), and advocating also importance of the environmental aspects of packaging technology as the key organizer of Japanese roadmap of lead‐free soldering and International Eco‐design Conference as well as the general chair of IEEE Workshop on Low Temperature Bonding for 3D integration. Currently he is also appointed as the president of Japan Institute for Electronics Packaging (JIEP).
CONTACT: E‐mail: suga@pe.t.u‐tokyo.ac.jp http://www.su.t.u‐tokyo.ac.jp/
报告简介：
The mechanism of bonding of solid materials has been considered based on the diffusion and reactions at elevated temperatures. However, chemical interactions between atoms on the mated surfaces exist always as the nature of the solid surface. These interactions are origin of the cohesive energy of solids as well as the adhesion energy between solids. It means that any solid materials should be bonded even if there is no high temperature reaction. This is the idea of the room temperature bonding.
The surface activated bonding (SAB) has been developed successfully to bond metals, Si, and III‐V semiconductors, attracted increasing interest due to its simple process flow and the room temperature process without heat and additional materials for bonding. It has been applied for volume production of SAW devices, metal laminates, and MEMS packaging.
The origin of SAB dates back to experiments on adhesion in the UHV conducted by NASA in the 1970s. The author’s group in the University of Tokyo made considerable progress in UHV bonding in the 1980s, and the technique was extended to apply to heterogeneous bondingbetween metals, and metals to ceramics, and semiconductors. For 3D‐IC, SAB was demonstrated to enable Cu‐Cu direct bonding at room temperature on a chip‐scale bump‐less interconnect of 1,000,000 electrodes consisting of 3 μm electrodes with 6 μm pitch. The possibility of applying SAB in ambient air has been also demonstrated on Au, AnSn, and SnAg, which are rather insensitive to oxidation.
A disadvantage of SAB was its difficulty of bonding ionic materials to each other, which include glass, sapphire and silicon dioxide. The reason for this is still not clear but it is assumed that the surface of ionic materials is spontaneously polarized at different levels by ion beam bombardment, which is performed prior to the bonding. To overcome the problem of the original SAB method, a modification was proposed. In this approach, the surfaces to be bonded are sputter cleaned by Ar and simultaneously deposited with Fe and subsequently Si. The metallic thin layer may shield the surface polarity of the ionic materials and therefore the wafers are bonded very strongly. By this modified method, room temperature bonding of SiO2, glass, and various single crystalline wafers as well as polymer films was achieved at room temperature with very high bond strength.
The application of the modified SAB is extended to sealing of glass and polymer devices such as Organic Electro‐Luminescent Display (OELD) or lightening devices, since there is no other suitable method for good sealing agent against permeation of water and oxygen from the atmosphere into those devices.
