Low Resistance and High Electromigration Lifetime of Cu-To-Cu Joints Using (111)-Oriented Nanotwinned Copper

Low Resistance and High Electromigration Lifetime of Cu-To-Cu Joints Using (111)-Oriented Nanotwinned Copper

Jing-Ye Juang1, Kai Cheng Shie1, Yu Jin Li1, K. N. Tu1,2, Chih Chen1,*

1Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan 30010, ROC

2Department of Materials Science and Engineering, University of California at Los Angeles, Los Angeles, California 90095, USA

Adv. Mater. Lett., 2021, 12 (8), 21081654

DOI: 10.5185/amlett.2021.081654

Publication Date (Web): Jul 05, 2021

E-mail: chih@mail.nctu.edu.tw

Abstract


Cu-to-Cu joints of 30 mm in diameter were fabricated using (111)-oriented nanotwinned copper at 300 °C for 20 min in N2 ambient. The joints possess excellent electrical properties. The average resistance and specific contact resistivity are 4.1 mΩ and 3.98 × 10-8 Ω·cm2, respectively for an as-fabricated Cu joint. With a second step annealing at 400 °C, the resistance can be reduced to 3.27 mΩ due to grain growth across the joint interface. There is 50% resistance reduction compared to SnAg solder joints with the same diameter. The electromigration lifetime for Cu-to-Cu joints is at least 750 times longer than solder joints.

Keywords

Cu-to-Cu direct bonding, nanotwinned Cu, grain growth, electromigration, resistance.

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