Thermal diffusivity measurement of low-k dielectric thin film by temperature wave analysis

Thermal diffusivity of thin film with low dielectric constant (k), what is called low-k dielectric thin film, 0.31-1.14 μm, including hydrogen-silsesquioxane (HSQ), methyl-silsesquioxane (MSQ), and poly(arylen ether) was examined by temperature wave analysis. The phase shift of temperature wave was observable up to 100 kHz. Thermal diffusivity of HSQ was 4.7 × 10⁻⁷ m² s⁻¹, on the other hand it was not higher than 1.1 × 10⁻⁷ m² s⁻¹ for MSQ or poly(arylen ether) at room temperature. Temperature dependence of thermal diffusivity/thermal conductivity of MSQ was obtained, thermal diffusivity decreased but thermal conductivity increased in a heating scan at 30-150 °C. It was shown that the thermal diffusivity of low-k thin film was correlated with the chemical and the physical structures, the latter was formed in the spin-coating and the curing process.