Evaluation of thermal cycle stress in SiC power devices by Raman spectroscopy

We investigated the thermal stress in silicon carbide metal-oxide-semiconductor field effect transistors (SiC MOSFETs) by Raman spectroscopy. We performed the thermal cycle tests of the SiC MOSFET. The horizontal compressive stress increased after the thermal cycle tests. The increase of compressive stress largely depended on the temperature conditions, and the compressive stress became large as the maximum temperature of the cycle test increased. The stress increasing didn't observe from the sample which was removed the solder and Cu plate. This result suggest that the improvement of die-attach materials is important to reduce the thermal stress in SiC MOSFETs. The quantitative stress evaluation by Raman spectroscopy can be used as an indicator of the deterioration process of the devices.