Chih Chen received his Ph.D. degrees in Materials Science of University of California at Los Angeles (UCLA) in 1999 in Prof. King-Ning Tu’s group. He served as lecturer at UCLA MSE from 1999-2000. He joined National Yang Ming Chiao Tung University (NYCU), Taiwan as an assistant professor in 2000. He is currently the chairman & distinguished professor of Department of Materials Science and Engineering in NYCU, Taiwan. Professor Chen discovered electrodeposition of (111)-oriented nanotwinned Cu, and reported it in Science 336, 1007-1010 (2012), and transferred the fabrication technology to Chemleaders, Inc, Taiwan for mass production in 2016. Therefore, he received the 2016 National Innovation Award, 2016 Materials Innovation Award, Materials Research Society, Taiwan, 2017 Outstanding Technology Transfer Award on Electroplating and Application of High (111)-oriented Nanotwinned Cu, 2018 Outstanding Researcher Award, Ministry of Science & Technology, Taiwan, TMS 2018 Research to Practice Award, The Minerals, Metals & Materials Society (TMS), USA. It is noteworthy to mention that TMS is the second largest materials society in the world and there are over 4000 members in TMS. There is only one recipient each year for the Research to Practice Award. He was recognized as fellow of International Association of Advanced Materials (IAAM) in 2020 and Fellow of The Materials Research Society-Taiwan (MRS-T) in 2022.
His current research interests are low-temperature Cu-to-Cu direct bonding, high strength nanotwinned Cu lines and films for 3D IC integration, reliabilities of flip-chip solder joints and microbumps for microelectronics packaging, including electromigration, thermomigration, and metallurgical reactions. He published 190+ journal papers and he holds 30+ Taiwan and US patents. He wrote a book with Prof. King-Ning Tu and Prof. H.M. Chen on Electronic Packaging Science and Technology, which has been published by Wiley in 2021.
1.Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsin-Chu, Taiwan 30010
2.Department of Materials Science and Engineering, National Chiao Tung University, Hsin-Chu, Taiwan 30010
Cu-to-Cu direct bonding has been implemented in high-end microelectronic devices with ultra-high input/output (I/O) density. The pitch of the Cu-Cu joints can be scaled below 1 µm, and thus its I/O density can be 300 times larger than that of the solder microbumps. In this presentation, the fundamental mechanism and interfacial microstructures of Cu-Cu direct bonding will be presented. A creep bonding model will be proposed. Then Cu/SiO2 hybrid bonding will be introduced. We adopted (111)-oriented Cu with high surface diffusivity to achieve low-temperature and low-pressure Cu/SiO2 hybrid bonding. The bonding temperature can be lowered from 300 °C to 200 °C, and the pressure is as low as 1.06 MPa. The bonding process can be accomplished by a 12-inch wafer-to-wafer or die-to-die scheme. The measured specific contact resistance is 1.2 x 10−9 Ω·cm2, which is the lowest value reported in literature for Cu-Cu joints bonded below 300 °C. The joints possess excellent electric properties up to 375 °C. Reliabilities of the Cu-Cu joints will be also presented.