Substrate-dependent thermal conductivity of aluminum nitride thin-films processed at low temperature

In this paper, we report on investigation concerning the substrate-dependent thermal conductivity (k) of Aluminum Nitride (AlN) thin-films processed at low temperature by reactive magnetron sputtering. The thermal conductivity of AlN films grown at low temperature (200 °C) on single-crystal silicon (Si) and amorphous silicon nitride (SiN) with thicknesses ranging from 100 nm to 4000 nm was measured with the transient hot-strip technique. The k values for AlN films on SiN were found significantly lower than those on Silicon consistently with their microstructures revealed by X-ray diffraction, high resolution scanning electron microscopy, and transmission electron microscopy. The change in k was due to the thermal boundary resistance found to be equal to 10 × 10−9 Km2W−1 on SiN against 3.5 × 10−9 Km2W−1 on Si. However, the intrinsic thermal conductivity was determined with a value as high as 200 Wm−1K−1 whatever the substrate.