ThermalScope: Multi-Scale Thermal Analysis for Nanometer-Scale Integrated Circuits

Abstract

Thermal analysis has long been essential for designing reliable, high-performance, cost-effective integrated circuits (ICs). Increasing power densities are making this problem more important. Characterizing the thermal profile of an IC quickly enough to allow feedback on the thermal effects of tentative design changes is a daunting problem, and its complexity is increasing. The move to nanoscale fabrication processes is increasing the importance of quantum thermal phenomena such as ballistic phonon transport. Accurate thermal analysis of nanoscale ICs containing hundreds of millions of devices requires characterization of thermal effects on length scales that vary by several orders of magnitude, from nanoscale quantum thermal effects to centimeter-scale cooling package impact. Existing chip.package thermal analysis methods based on classical Fourier heat transfer cannot capture nanoscale quantum thermal effects. However, accurate device-level modeling techniques, such as molecular dynamics methods, are far too slow for use in full-chip IC thermal analysis. In this work, we propose and develop ThermalScope, a multi-scale thermal analysis method for nanoscale IC design. It unifies microscopic and macroscopic thermal physics modeling methods, i.e., the Fourier and Boltzmann transport modeling methods. Moreover, it supports adaptive multi-resolution modeling. Together, these ideas enable efficient and accurate characterization of nanoscale quantum heat transport as well as chip.package level heat flow. ThermalScope is designed for full-chip thermal analysis of billion-transistor nanoscale IC designs, with accuracy at the scale of individual devices. ThermalScope enables accurate characterization of temperature-related effects, such as variation in leakage power and delay. ThermalScope has been implemented in software and used for full-chip thermal analysis and temperature-dependent leakage analysis of an IC design with more than 150 million transistors. It will be publicly released for free academic and personal use.