Spatiotemporal thermal characterization for 3D stacked chiplet systems based on transient thermal simulation

Yanrong Pei ^a , Wenchang Li ^a, Rong Chen ^b
a Laboratory of Solid-State Optoelectronic Information Technology, Institute of Semiconductors, Chinese Academy of Sciences, China 
^b National Key Laboratory of Integrated Circuits and Microsystems, China

Abstract

Vertically dominant heat flow in three-dimensional stacked chiplet systems (3D SCSs), driven by high heat flux density, induces severe hotspots and pronounced temperature non-uniformities, posing critical challenges to performance stability and long-term reliability. Transient thermal characterization thus requires accurate and fast simulation coupled with analysis of heat conduction mechanisms. To address this, we propose a unified framework integrating an explicit 3D general high-order finite difference (GHOFD) method with cone-fused heat flux streamlines (CFHFSs). The GHOFD method achieves a numerical error of less than 0.01 °C relative to the analytical solution. It demonstrates a computational speedup of more than 50x compared to the state-of-the-art alternating direction implicit (ADI) method. Applied to two representative 3D SCS models under Dirichlet and Robin boundary conditions, the framework reveals an inherently anisotropic and spatially non-uniform thermal behavior, dominated by vertical conduction yet modulated by the chiplets' layout and power distribution. The CFHFS elucidates 3D thermal behavior through qualitative streamline attributes (e.g., density, deflection) and cone size proportional to local heat flux magnitude. This integrated approach not only predicts thermal behavior with high accuracy and speed but also reveals the underlying 3D heat conduction mechanisms, offering actionable insights for thermal design, thermal analysis, and thermal management of next-generation heterogeneous chiplet systems.

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