Thermal conduction in sub-100 nm transistors

Heat conduction in integrated circuits spans length scales across several orders of magnitude: From the lattice spacing at a few Angstroms to the substrate thickness at hundreds of micrometers. The smaller length scale becomes increasingly important in devices with feature size well below 100 nm. This paper provides an overview of sub-continuum electro-thermal transport. We use the phonon Boltzmann transport equation to model heat conduction in the device and show that phonons emitted by hot electrons in the drain create a phonon hotspot. The resulting non-equilibrium leads to increased thermal resistance within the device. At the limits of scaling, the resistance is comparable to that due to the substrate and packaging.