Heat transport in thin dielectric films

Heat transport in 20-300 nm thick dielectric films is characterized in the temperature range of 78-400 K using the 3 omega method. SiO2 and SiNx films are deposited on Si substrates at 300 degrees using plasma enhanced chemical vapor deposition (PFCVD). For films >100 nm thick, the thermal conductivity shows little dependence on film thickness: the thermal conductivity of PECVD SiO2 films is only similar to 10% smaller than the conductivity of SiO2 grown by thermal oxidation. The thermal conductivity of PECVD SiNx films is approximately a factor of 2 smaller than SiNx deposited by atmospheric pressure CVD at 900 degrees C. For films <50 nm thick, the apparent thermal conductivity of both SiO2 and SiNx films decreases with him thickness. The thickness dependent thermal conductivity is interpreted in terms of a small interface thermal resistance R(I). At room temperature, R(I) similar to 2 x 10(-8) K m(2) W-1 and is equivalent to the thermal resistance of a similar to 20 nm thick layer of SiO2. (C) 1997 American Institute of Physics.