Phys.org November 4, 2024
As metallic nanostructures shrink towards the size of the electronic mean free path, thermal conductivity decreases due to increased electronic scattering rates. Matthiessen’s rule is commonly applied to assess changes in electron scattering rates, although this rule has not been validated experimentally at typical operating temperatures for most of the electronic systems. A team of researchers in the US (University of Virginia, University of Rhode Island, Oak Ridge National Laboratory, Intel Corporation) experimentally evaluated the validity of Matthiessen’s rule in determining the thermal conductivity of thin metal films by measuring the in-plane thermal conductivity and electronic scattering rates of copper films with varying thicknesses (27 nm — 5 µm), microstructures, and grain boundary segregation. They found that the electron-phonon coupling factor was independent of film thickness, whereas the total electronic scattering rate increased with decreasing film thickness. According to the researchers their findings provided experimental validation of Matthiessen’s rule for electron transport in thin metal films at room temperature and also introduced an approach to discern critical heat transfer processes in thin metal interconnects, which holds significance for the advancement of future CMOS technology… read more. Open Access TECHNICAL ARTICLE
The appearance of grain boundary segregation due to annealing. Credit: Nature Communications volume 15, Article number: 9167, 24 October, 2024Â