Prediction and Measurement of the Thermal Conductivity of Amorphous Dielectric Layers

Thermal conduction in amorphous dielectric layers affects the performance and reliability of electronic circuits. This work analyzes the influence of boundary scattering on the effective thermal conductivity for conduction normal to amorphous silicon dioxide layers, k_n,eff. At 10 K, the predictions agree well with previously reported data for deposited layers, which show a strong reduction of k_n,eff compared to the bulk conductivity, k_bulk. A steady-state technique measures k_n,eff near room temperature of silicon dioxide layers fabricated using oxygen-ion implantation (SIMOX). The predictions and the SIMOX data, which agree closely with k_bulk, show that boundary scattering is not important at room temperature. Lower than bulk conductivities of silicon dioxide layers measured elsewhere near room temperature must be caused by interfacial layers or differences in microstructure or stoichiometry.