Step-Bunching Free and 30 μm-Thick SiC Epitaxial Layer Growth on 150 mm SiC Substrate

The production of 150 mm-diameter SiC epi-wafers is the key to the spread of SiC power devices. Besides, step-bunching free surface leads to high-performance devices. We have developed the production technology of the epitaxial growth with smooth surface morphology for 4º off Si-face 4H-SiC epitaxial layers on 150 mm diameter substrates. The various area observations of the surface by optical surface analyzer, confocal microscope and atomic force microscope revealed that there was no conventional step-bunching in whole wafer surface. While creating step-bunching free surface is more difficult for thicker epilayer growth, we have achieved step-bunching free surface for 30-μm thick epilayer on a 150 mm diameter substrate. The typical values of thickness uniformity of the 30μm-thick epilayer are 0.5% (σ/mean) and 1.7% (range/mean). A few interfacial dislocations (IDs) were detected for the 150 mm-diameter epi-wafer by reflection X-ray topography. We have succeeded in removal of IDs by the optimized growth condition.