Predicting thermal behavior of interconnects

Previous investigations into thermal characteristics of embedded interconnects produced a wafer level technique for measurement of the thermal conductance, as well as a quasi-analytical model for predicting the results (Harmon, Gill and Sullivan, IRW 1998). In this paper, measurements of the thermal characteristics of embedded interconnects with underlying insulator thicknesses from 1.0 to 0.1 μm are presented. These measurements indicate the thermal conductance for thin insulators is significantly less than that predicted by the quasi-analytical model. Through finite element modeling, this discrepancy is shown to be due to localized substrate heating. An “effective conductivity” method is presented to extend the quasi-analytical model to include substrate-heating effects. This same approach is proposed for analysis of composite insulator structures including low K dielectrics. The methodology is assessed by comparing modeled and measured fuse current densities for embedded interconnects of varying width and underlying insulator thickness