Quantitative thermal imaging by synchronous thermoreflectance with optimized illumination wavelengths

Using thermoreflectance microscopy with a camera, we have designed a system which delivers submicronic images of the alternative temperature variation s in integrated circuits working in a modulated regime. A careful choice of the illumination wavelength permits us to highlight the heating in chosen parts of the sample and to optimize the thermoreflectance signal. We measur e and explain the modifications of the photothermal response which are indu ced by the presence of a passivation layer. A calibration conducted on vari ous materials with a thermocouple gives access to the absolute alternative temperature variations in integrated circuits working at frequencies betwee n 0.1 Hz (quasipermanent regime) and 5 MHz. (C) 2001 American Institute of Physics.