Suppression of In-Grown SF Formation and BPD Propagation in 4H-Sic Epitaxial Layer by Sublimating Sub-Surface Damage before the Growth

Abstract

It is known that basal plane dislocations (BPDs) and in-grown stacking faults (IGSFs) in the 4H-SiC epitaxial layer cause severe electrical degradation in SiC devices. The impact that sub-surface damage (SSD) on a production-grade 4H-SiC substrate with CMP-finished surface causes on both the BPD propagation and IGSF formation during epitaxial growth was investigated by Dynamic AGE-ing (DA). The substrates etched by DA sublimation etching to adjust the residual amount of SSD maintaining a smooth surface without macro step bunching were grown to observe BPD and IGSF density. The obtained results showed that these defect densities decreased exponentially with increasing etching depth. We demonstrated SSD introduced by mechanical processing led BPDs and IGSFs to extend or introduce to the epitaxial layer.