Thermal conductivity measurements of thin silicon dioxide films in integrated circuits

The thermal conductivity of thin silicon dioxide (SiO₂) films is measured using specialized test structures. The test structures consist of parallel plate-electrodes that sandwich the dielectric whose thermal conductivity is determined. The accuracy of the measurement technique is verified based on simulations. Films with thicknesses in the range of 0.57 μm to 2.28 μm are investigated. At room temperature the thin films exhibit a thermal conductivity of ~1.1 W/Km which is approximately 20% below that of bulk fused SiO₂. As opposed to prior studies, the thermal conductivity of the thin films is observed to increase with rising temperature. Temperature dependence of thermal conductivity is found to be very similar to that of bulk fused SiO₂. The impart of thermal resistances at boundaries between silicon dioxide and metallization is shown to be insignificant for the films investigated. In addition, no dependence of thermal conductivity on film thickness is observed. Vias are found to be very effective in reducing thermal resistance between adjacent metallization layers