Agradecimentos: The authors acknowledge the Brazilian agencies FAPESP, CNPq, and FAEPEX-Unicamp, as well as CONACYT, México, for financial support. This work was supported by research Grant Nos. SIP-IPN-20150390, 20160144, and CONACyT-2011-01-174247. The support of COFAA-IPN through the SIBE and BEIFI Programs is also greatly acknowledged Ver menos

Abstract: In this work a combined thermoacoustic and thermoreflectance set-up was designed for imaging biased microelectronic circuits. In particular, it was used with polycrystalline silicon resistive tracks grown on a monocrystalline Si substrate mounted on a test chip. Thermoreflectance images, obtained by scanning a probe laser beam on the sample surface, clearly show the regions periodically heated by Joule effect, which are associated to the electric current distribution in the circuit. The thermoacoustic signal, detected by a pyroelectric/piezoelectric sensor beneath the chip, also discloses the Joule contribution of the whole sample. However, additional information emerges when a non-modulated laser beam is focused on the sample surface in a raster scan mode allowing imaging of the sample. The distribution of this supplementary signal is related to the voltage distribution along the circuit Ver menos