Hot-Spot Detection in Integrated Circuits by Substrate Heat-Flux Sensing

This letter presents a novel approach to detect hot spots (HSs) in active integrated circuits (ICs) and devices. It is based on sensing the HS heat flux within the chip substrate with a probe-laser beam. As the beam passes through the die, it experiences a deflection directly proportional to the heat flux found along its trajectory (internal infrared laser deflection technique). The proposed strategy allows inspecting the chip through its lateral sides (lateral access), avoiding the metal and passivation layers placed over the die. The obtained results demonstrate the suitability of this technique to locate and characterize devices behaving as hot spots in nowadays IC CMOS technologies.