Thermal Conductivity of Thin Dielectric Films

The 3ω method is used for the thermal conductivity measurement of ultra thin dielectric films of SiO₂ and MgO. The films are deposited on a small opening of Si substrate covered with 200 nm thick insulation layer. This method greatly reduced the probability of getting short-circuited between the heater and Si substrate. With this improvement, the 3ω method has been used to measure the thermal conductivity of 20 – 300 nm thick SiO₂ and MgO films deposited on Si substrate by plasma enhanced chemical vapor deposition and reactive sputtering method, respectively. Our results are consistent with the several previous reports obtained by different methods. The thermal resistance at the film interfaces is ~2×10⁻⁸ m²KW⁻¹ for these films. We suggest that the thermal conductivity of these films is intrinsically thickness-independent for the measured film thickness range.