Reduction of defects propagating into 3C-SiC homoepilayers by reactive ion etching of 3C-SiC heteroepilayer substrates

Abstract

The crystallinity and morphology of single-crystal 3C-SiC homoepilayers grown on heteroepilayer (0 0 1) substrates by low-pressure chemical vapor deposition were investigated. The crystalline qualities of homoepilayers were critically dependent upon the defects of heteroepilayer substrates because planar defects, predominantly stacking faults and twins, and protrusions existing on the heteroepilayer surface propagated into the homoepilayers. A surface etching process using reactive ion etching (RIE) of the backside of free-standing heteroepilayers, the interface with Si substrates, was proposed to minimize the defect densities on the heteroepilayer surface. Analyses of high resolution X-ray diffraction (HRXRD) and atomic force microscope (AFM) reveal that simultaneous reductions of both surface roughness and defect densities on the heteroepilayer surface are achieved by an etching depth of 4 μm. Cross-sectional scanning electron microscopy (SEM) observation clearly shows that protrusions on the RIE-treated heteroepilayer surface are readily buried by growing homoepilayers. Furthermore, the results of cross-sectional transmission electron microscopy (XTEM) indicate that (i) significant amounts of planar defects are removed by the RIE process of the backside of heteroepilayers and (ii) most of planar defects propagating into the homoepilayers are terminated by coalescences between one another during early homoepitaxial growth stages.