Thermal Analysis in Chip Design is the simulation and optimization of temperature distribution across an IC die under realistic workloads, identifying hotspots causing timing degradation, reliability failures, and potential thermal runaway.

Temperature impacts everything: timing — carrier mobility decreases ~0.2%/C, gate delay increases ~10-15% per 25C rise; leakage — subthreshold leakage doubles every ~10C (positive feedback loop); reliability — electromigration lifetime follows Arrhenius dependence; interconnect — metal resistivity increases ~0.4%/C, worsening IR drop.

Simulation Methodology:

Power Map Generation: Spatially-resolved from: gate-level switching activity, temperature-dependent leakage (requiring iterative thermal-power convergence), memory macro power, and I/O power. Modern SoCs can exceed 1 W/mm2 peak locally.

Hotspot Analysis: Common causes: clock tree buffers at clock root, high-activity datapaths (multipliers, FPUs), memory macros with continuous access, voltage regulators, and SerDes PHYs with analog bias currents.

Thermal-Aware Optimization: Floorplanning — spread high-power blocks, avoid vertical stacking in 3D-IC; placement — cell density constraints in hot regions; clock design — distribute clock buffers; DVFS — cap power in thermal-critical scenarios; dark silicon management — schedule workloads to distribute heat temporally.

3D-IC Challenge: Heat from bottom die conducts through top die to heat sink. Thermal coupling creates mutual heating. TSVs provide limited relief. Research: microfluidic cooling between dies.

Thermal analysis has evolved from post-signoff check to first-class design constraint — increasing power density, temperature-sensitive FinFET leakage, and 3D integration make thermal management as important as timing closure.