Cu-C interface systems evaluated with the help of the thermal wave contrast

The effective thermal depth profiles of copper-carbon interface systems with and without additional metallic submicron bond layers have been measured by means of modulated IR radiometry and have been evaluated using a new quantity, the thermal (wave) contrast, defined with the help of the calibrated thermal wave amplitudes. Useful correlations between the thermal wave contrast and the mechanical adhesion strength between copper film and carbon substrate have been found. By comparing the measurements based on thermal wave excitation and contact-less IR detection with microscopic contact temperature measurements close to the copper-carbon interface, the similarities between the two experiments are discussed, and the advantages and problems related to the thermal wave contrast are analyzed.