Fine-pitch Cu-Cu Hybrid Bonding Using Electroless-deposited (111) Nanotwinned Cu
Part Of
Proceedings - Electronic Components and Technology Conference
Start Page
793
End Page
797
ISSN
05695503
ISBN (of the container)
9798331564179
ISBN
9798331564179
Date Issued
2026
Author(s)
Lee, Wei Choong
Shih, Po-Shao
Chen, I-En
Yang, Cheng-Yan
Lu, Yu-Hsiang
Hung, Yun-Ching
Lin, Yung-Sheng
Wang, Chen-Chao
Hung, Chih-Pin
Abstract
To enable the high-density interconnections required for advanced packaging in Artificial Intelligence (AI) and High Performance Computing (HPC) applications, hybrid bonding has emerged as a key enabling technology. Compared with conventional fabrication methods, electroless deposition provides a straightforward and autocatalytic approach for the synthesis of nanotwinned copper (nt-Cu). This work demonstrates the uniform and selective electroless deposition of highly (111)-textured nt-Cu pads on a fine-pitch polyimide (PI) hybrid bonding test vehicle (10 μm diameter, 30 μm pitch). Both theoretical calculations and experimental results indicate that a Cu surface protrusion is vital for achieving high-quality hybrid bonding due to the higher coefficient of thermal expansion (CTE) of PI relative to nt-Cu. Accordingly, an optimized Chemical Mechanical Planarization (CMP) process was developed to establish a surface topography featuring protruding Cu pads and a recessed PI region, as verified by atomic force microscopy (AFM). This enabled the formation of robust nt-Cu/PI hybrid joints bonded at 250 °C and 10 MPa for 1 hour, without the need for post-bonding annealing, as revealed by focused ion beam (FIB) cross-sectional analysis. These results highlight the potential of electroless deposited nt-Cu for the next-generation fine-pitch packaging.
Event(s)
76th IEEE Electronic Components and Technology Conference, ECTC 2026, 26 May 2026 - 29 May 2026, Orlando
Subjects
3D integration
advanced packaging
Cu/PI hybrid bonding
Electroless deposition
fine pitch
nanotwinned Cu
Publisher
Institute of Electrical and Electronics Engineers Inc.
Type
conference paper