Compact modeling and SPICE-based simulation for electrothermal analysis of multilevel ULSI interconnects

This paper presents both compact analytical models and fast SPICE based 3-D electro-thermal simulation methodology to characterize thermal effects due to Joule heating in high performance Cu/low-k interconnects under steady-state and transient stress conditions. The results demonstrate excellent agreement with experimental data and those using Finite Element (FE) thermal simulations (ANSYS). The effect of vias, as additional heat sinking paths to alleviate the temperature rise in the metal wires, is included in our analysis to provide more accurate and realistic thermal diagnosis. It shows that the effectiveness of vias in reducing the temperature rise in interconnects is highly dependent on the via separation and the dielectric materials used. The analytical model is then applied to estimate the temperature distribution in multi-level interconnects. In addition, we discuss the possibility that, under the impact of thermal effects, the performance improvement expected from the use of low-k dielectric materials may be degraded. Furthermore, thermal coupling between wires is evaluated and found to be significant. Finally, the impact of metal wire aspect ratio on interconnect thermal characteristics is discussed.