Differential 3ω method for measuring thermal conductivity of AlN and Si3N4 thin films

The thermal conductivity λ of plasma enhanced chemical vapor deposited Si3N4 and sputtered AlN thin films deposited on silicon substrates were obtained utilizing the differential 3ω method. A thin electrically conductive strip was deposited onto the investigated thin film of interest, and used as both a heater and a temperature sensor. To study the thickness dependent thermal conductivity of AlN and Si3N4 films their thickness was varied from 300 to 1000nm. Measurements were performed at room temperature at a chamber pressure of 3.1Pa. The measured thermal conductivity values of AlN and Si3N4 thin films were between 5.4 and 17.6Wm−1K−1 and 0.8 up to 1.7Wm−1K−1, respectively. The data were significantly smaller than that of the bulk materials found in literature (i.e., λAlN=250–285Wm−1K−1, λSi3N4=30Wm−1K−1), due to the scaling effects, and also strongly dependent on film thickness, but were comparable with literature for the corresponding thin films. •AlN thin films with different film thicknesses were prepared on Si-substrates.•Thermal conductivity of AlN thin films was determined using the differential 3ω method.•Thermal conductivity for thin films is clearly lower than the bulk material values.•Thermal conductivity of AlN thin films decrease with decreasing film thickness.