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http://dx.doi.org/10.6117/kmeps.2021.28.3.009

Evaluation of 12nm Ti Layer for Low Temperature Cu-Cu Bonding  

Park, Seungmin (Department of Manufacturing System and Design Engineering, Seoul National University of Science and Technology)
Kim, Yoonho (Department of Manufacturing System and Design Engineering, Seoul National University of Science and Technology)
Kim, Sarah Eunkyung (Department of Nano-IT Convergence Engineering, Seoul National University of Science and Technology)
Publication Information
Journal of the Microelectronics and Packaging Society / v.28, no.3, 2021 , pp. 9-15 More about this Journal
Abstract
Miniaturization of semiconductor devices has recently faced a physical limitation. To overcome this, 3D packaging in which semiconductor devices are vertically stacked has been actively developed. 3D packaging requires three unit processes of TSV, wafer grinding, and bonding, and among these, copper bonding is becoming very important for high performance and fine-pitch in 3D packaging. In this study, the effects of Ti nanolayer on the antioxidation of copper surface and low-temperature Cu bonding was investigated. The diffusion rate of Ti into Cu is faster than Cu into Ti in the temperature ranging from room temperature to 200℃, which shows that the titanium nanolayer can be effective for low-temperature copper bonding. The 12nm-thick titanium layer was uniformly deposited on the copper surface, and the surface roughness (Rq) was lowered from 4.1 nm to 3.2 nm. Cu bonding using Ti nanolayer was carried out at 200℃ for 1 hour, and then annealing at the same temperature and time. The average shear strength measured after bonding was 13.2 MPa.
Keywords
Ti passivation; Cu bonding; 3D packaging; Solid state diffusion; Chip bonding;
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