Modeling and analysis of via hot spots and implications for ULSI interconnect reliability

The prediction of hot spot temperatures and positions in interconnect and via systems is necessary for improved thermal design to minimize electromigration, stress migration, and high-current failures. While some thermal models are available for multilevel interconnect systems, the effects of vias are either neglected or treated very approximately. This paper derives an accurate analytical model for estimating interconnect and via temperatures, and also verifies the model using finite-element simulations. The model shows that hot spot locations and the overall temperature field in the interconnect structure are strongly affected by via and line dimensions. A critical condition for hot spot formation within the vias has been presented for the first time. Additionally, a new analytical model for estimating the temperature rise in a multilevel interconnect system has also been derived, which incorporates the effect of via self-heating. This work provides the basis for constitutive design rules considering hot spot locations and temperature profiles in interconnect systems.