Thermal conductivity study of porous low-k dielectric materials

Abstract

An experimental method based on the 3ω technique has been developed to measure thermal conductivity of porous Xerogel films as a function of porosity. The results show that the thermal conductivity of these porous dielectric films can be an order of magnitude smaller than that of SiO2. To account for the porosity dependence of thermal conductivity, two porosity weighted semiempirical models are introduced. These models suggest the scaling rule expressing the thermal conductivity as a function of porosity. The decrease observed in thermal conductivity of porous films suggests that the tradeoff between thermal and electrical performance is an important consideration when implementing porous dielectric materials as interlevel dielectrics for on-chip interconnects.