Effects of heating strategies and ballistic transport on the transient thermal conduction in 3D FinFETs

Abstract

Efficiently capturing the three-dimensional spatiotemporal distributions of temperature is of great significance for alleviating hotspot issues in 3D FinFETs. However, most previous thermal simulations mainly focused on the steady-state problem with continuous heating. Few studies are conducted for the transient thermal conduction in 3D FinFETs with non-continuous heating, which is actually closer to the reality. To investigate the effects of heating strategies on the transient micro/nano scale thermal conduction in 3D FinFETs, three heating strategies are considered, including `Continuous', `Intermittent' and `Alternating' heating. A comparison is made between the phonon BTE solutions and the data predicted by the macroscopic diffusion equation, where the effect of boundary scattering on phonon transport is added into the effective thermal conductivity. Numerical results show that it is not easy to accurately capture the heat conduction in 3D FinFETs by the macroscopic diffusion equation, especially near the hotspot areas where ballistic phonon transport dominates and the temperature diffusion is no longer valid. Different heating strategies have great influence on the peak temperature rise and transient thermal dissipation process. Compared to `Intermittent' or `Continuous' heating, the temperature variance of `Alternating' heating is smaller.