Abstract
Heat transport in 30–300 nm thick dielectric films is characterized in the temperature range of 74–300 K using the 3ω method, which is a simple method to measure the cross-plane thermal conductivity of dielectric thin films. Dielectric film samples of two kinds, deposited on Si substrates using plasma enhanced chemical vapor deposition (PECVD) and grown by thermal oxidation, were measured in the cryogenics system. The apparent thermal conductivity, intrinsic thermal conductivity, and interface resistance have been analyzed in different environment temperature. The measured data with this method were verified with the measurement results from published data, which showed satisfactory agreement. For this experiment, we discovered the thermal conductivity of PECVD SiO2 films was smaller than the conductivity of SiO2 grown by thermal oxidation, because the porosity of thermal SiO2 is smaller than PECVD SiO2. The apparent thermal conductivity of SiO2 films decreases with film thickness. The thickness dependent thermal conductivity is interpreted in terms of a small interface thermal resistance RI. For SiO2 films, the thermal conductivity decreases if the temperature decreases, because the mean free path of heater carriers increases. 3ω method combined with the cryogenics system could not only measure the thermal conductivity of SiO2 accurately, but also treat the influence of thermal conductivity on different temperature environment. In the future, we could broaden the use of this combination to measure other thin films.