Researchers at University of South Florida (USF), Tampa, Fla., developed a novel approach to mitigating electromigration in nanoscale electronic interconnects, ubiquitous in state-of-the-art integrated circuits. USF Mechanical Engineering assistant professor Michael Cai Wang and his research team achieved this by coating copper metal interconnects with hexagonal boron nitride (hBN), an atomically-thin insulating two-dimensional (2D) material that shares a similar structure as graphene.
Electromigration is the phenomenon in which an electrical current passing through a conductor causes the atomic-scale erosion of the material, eventually resulting in device failure. Conventional semiconductor technologies address this challenge by using a barrier or liner material, but this takes up precious space on the wafer that could otherwise be used to pack in more transistors. Wang’s approach accomplishes this same goal, but with the thinnest possible materials in the world, two-dimensional (2D) materials.
Angstrom-thin hexagonal boron nitride (hBN) is a highly promising barrier/liner dielectric material for passivating electrical interconnects in ultra-scaled integrated circuits. Significant improvements in the breakdown current density and operating lifetime have been observed in hBN-passivated copper interconnects, paving the way for further single-nanometer node scaling of semiconductor and ICs manufacturing.
“This work introduces new opportunities for research into the interfacial interactions between metals and angstrom-scale 2D materials. Improving electronic and semiconductor device performance is just one result of this research. The findings from this study opens up new possibilities that can help advance future manufacturing of semiconductors and integrated circuits,” Wang said. “Our novel encapsulation strategy using single-layer hBN as the barrier material enables further scaling of device density and the progression of Moore’s Law.”
In their recent study, copper interconnects passivated with a monolayer hBN via a back-end-of-line (BEOL) compatible approach exhibited more than 2500% longer device lifetime and more than 20% higher current density than otherwise identical control devices.
“Our findings are not limited only to electrical interconnects in semiconductor research. The fact that we were able to achieve such a drastic interconnect device improvement implies that 2D materials can also be applied to a variety of other scenarios.” Wang added.
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