Year: 2025
Type: article
Abstract: This study investigates the use of nanocrystalline Cu (NC-Cu) to suppress interfacial voids in low-temperature Cu-Cu bonding for 3D IC packaging. We quantitatively compared the void characteristics of electrodeposited NC-Cu (grain size ~89.3 nm) and (111)-oriented nanotwinned Cu (NT-Cu, ~621.8 nm) bonded at 200 °C. Plan-view STEM-HAADF analysis revealed that NC-Cu achieved a much lower void area ratio (1.8%) than NT-Cu (4.0%), attributed to its high grain boundary density, which enhances atomic diffusion and grain boundary migration. At 250 °C, typical Ostwald ripening was observed, with fewer but larger voids. However, a rise in total void area fraction suggests a competing mechanism-possibly new void nucleation at grain boundaries triggered by residual defects from the electroplating process. These results highlight the superior void-mitigating capability of NC-Cu under low thermal budgets.
Source: Materials
DOI: 10.3390/ma18163725
Authors: Jian-Yuan Huang, Dinh-Phuc Tran, Kang-Ping Lee, Yi-Quan Lin, Emile Kuo, Tsung-Chuan Chen, Yao-Tsung Chen, Stream Chung, Chih Chen
Institution: National Yang Ming Chiao Tung University
Language: English
Topic: 3D IC and TSV technologies
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,137
OpenAlex ID: W4413248382