Imaging and Metrology of Silicon Carbide Wafers by Laser-Based Optical Surface Inspection System

There is a great need for an in-line, high-speed and non-destructive inspection system capable of evaluating and analyzing the quality of SiC wafers for SiC power devices. We have examined whether the laser-based optical non-destructive inspection system by KLA-Tencor meets these requirements. Using this system, incoming inspection of purchased SiC wafers has been performed. The obtained inspection data show that micropipe density is sufficiently low in a device-grade wafer, and therefore, micropipes are not the main cause of device failure. The next challenges for a device-grade SiC wafer are reduction of epitaxial defects and relatively small defects classified as “particles”.