PROCESS-INDUCED MORPHOLOGICAL DEFECTS IN EPITAXIAL CVD SILICON-CARBIDE

Silicon carbide (SiC) semiconductor technology has been advancing rapi dly, but there are numerous crystal growth problems that need to be so lved before SiC can reach its full potential. Among these problems is a need for an improvement in the surface morphology of epitaxial films that are grown to produce device structures. Various processes before and during epilayer growth lead to the formation of morphological def ects observed in SIC epilayers grown on Sic substrates. In studies of both 6H and BH-SIC epilayers, atomic force microscopy (AFM) and other techniques have been used to characterize SiC epilayer surface morphol ogy. In addition to the well-known micropipe defect, SiC epilayers con tain growth pits, triangular features (primarily) in 4H-SiC, and macro step due to step bunching. In work at NASA Lewis, it has been found t hat factors contributing to the formation of some morphological defect s include: defects in the substrate bulk, defects in the substrate sur face caused by cutting and polishing the wafer. the tilt angle of the wafer surface relative to the basal plane, and growth conditions. Some of these findings confirm results of other research groups. This pape r presents a review of published and unpublished investigations into p rocesses that are relevant to epitaxial film morphology.