Analytical extraction of thermal conductivities of low k dielectrics for advanced technologies

As the dimensions of IC structures shrink and dissipated power densities increase, thermal considerations have a growing importance in the development of advanced microelectronic components. Optimal thermal management requires the accurate knowledge of the thermal conductivities of their constitutive thin films. Actually, a precise knowledge of these material parameters is essential to predict the thermal behavior of the IC and then to take it into account in reliability issues. The present paper provides an analytical thermal resistance model used to extract the conductivities of fluorinated silicate glass (FSG), phosphorous silicate glass (PSG) and silicate carbide oxide (SiOCH). Joule heating measurements at 25°C performed on embedded copper lines have validated this model. Various dielectric stack configurations have been studied to isolate the contribution of each material in the thermal model. From these results, root mean square (rms) currents have been predicted to limit Joule heating in interconnects.