Modulated photothermal reflectance technique for measuring thermal conductivity of nano film on substrate and thermal boundary resistance

The thermal conductivities of thermally oxidated SiO2 films of 98 nm, 148 nm, and 322 nm in thickness on Si substrate are measured using modulated photothermal reflectance technique. In the measuring principle, the equivalent transmission-line analysis is applied to the multilayer heat conduction problem and the simulated annealing algorithm is applied in the inverse analysis for determining the thermal conductivity and thermal boundary resistance. The thermal conductivity of the nano-SiO2 film is found being less than its bulk value and thickness dependent. The thermal boundary resistance between SiO2 and Al coating is found being comparable to the thermal resistance of the SiO2 layer.