Evaluation of residual thermal stress in Cu metalized silicon nitride substrates by raman spectroscopy

Local thermal stress is a critical issue in high-temperature packaging technologies. In the power module heat-releasing metalized ceramic substrates become more and more important. Large difference in coefficients of thermal expansion between ceramic and metal generates extensive thermal stress near the bonded interface of the metalized substrate. In this study local thermal stress generated in the ceramic part of Cu metalized Si3N4 substrate was evaluated by Raman spectroscopic analysis. The tensile stress of about 50 MPa was measured in the ceramic part near the interface of Cu plate.