Work

Electric‐Current‐Induced Phase Transformation in Cu 6 Sn 5 Below Its Equilibrium Transition Temperature

Year: 2026

Type: article

Abstract: ABSTRACT As semiconductor interconnects scale toward sub‐2 nm nodes, they are subjected to increasingly high current densities that challenge materials reliability. While phase transformations are traditionally interpreted through thermal equilibrium, electric current can introduce additional nonequilibrium effects that influence structural evolution. Here, we report a current‐driven monoclinic‐to‐hexagonal transformation in Cu 6 Sn 5 occurring under a measured bulk temperature of ∼120°C, below the equilibrium η′ ↔ η transition temperature of 186°C–189°C. Using an ex situ synchrotron X‐ray diffraction series on separate current‐stressed samples together with transmission electron microscopy, we show that matched bulk‐temperature thermal aging alone did not reproduce the same transformation within the examined time window, whereas current stressing progressively converted η′‐Cu 6 Sn 5 to η‐Cu 6 Sn 5 . The transformed state also exhibits a higher measured indentation modulus and hardness than the monoclinic reference under the present test conditions. These results demonstrate that electric current can drive unconventional structural evolution in Cu 6 Sn 5 below the equilibrium transition temperature and provide a basis for understanding current‐assisted phase stability in conductive intermetallics.

Source: Advanced Science

DOI: 10.1002/advs.75499

Authors: Shih‐kang Lin, Shubhayan Mukherjee, Yu‐chen Liu, Jun Mizuno

Institution: National Cheng Kung University

Language: English

Topic: Copper Interconnects and Reliability

Subfield: Electronic, Optical and Magnetic Materials

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $6,730

Funder: National Science and Technology Council