Comparison of Propagation and Nucleation of Basal Plane Dislocations in 4H-SiC(000-1) and (0001) Epitaxy

Abstract

Propagation and nucleation of basal plane dislocations (BPDs) in 4H-SiC(000-1) and (0001) epitaxy were compared. Synchrotron reflection X-ray topography was performed before and after epitaxial growth to classify the BPDs into those propagated from the substrate into the epilayer and those nucleated in the epilayer. It was revealed that the propagation ratio of BPDs for the (000-1) epitaxy was significantly smaller than that for the (0001) epitaxy. Growing (000-1) epilayers at a high C/Si ratio of 1.2 achieves a further reduction in BPDs to only 3 cm-2 for those propagated from the substrate, and 16 cm-2 for those nucleated in the epilayer. A dramatic increase was also found in the nucleation of BPDs omitting the re-polishing and in-situ H2 etching procedure.

Material science and device physics in SiC technology for high-voltage power devices

“…87,117,118) It is known that a perfect BPD in SiC is dissociated into two partial dislocations, and a single SSF is created between the two partials, where the SSF width is about 30-70 nm. 119) Conversion from BPDs to TEDs is enhanced by several techniques such as molten KOH etching 120,121) or H 2 etching 122) prior to epitaxial growth or interruption during growth. 123) The use of a substrate with a smaller off-angle is naturally effective in enhancing the conversion owing to the increased image force.…”

Defect engineering in SiC technology for high-voltage power devices

“…It is noted that if the growth rate is further increased, the risk of generation of in-grown stacking faults in the epitaxial layers increases. 399,400) It is also essential to remove the subsurface damage introduced during a polishing process by either chemical-mechanical polishing or appropriate H 2 etching, 401) since the mechanical stress induced by surface polishing can create BPD half loops near the surface. [402][403][404] If such BPD half loops remain at the time of epitaxial growth, the BPD (and TED) density in the epitaxial layer will increase.…”

Bulk and epitaxial growth of silicon carbide

“…Some BPDs are, however, replicated in a SiC epitaxial layer; it has been discovered that all these BPDs propagating in basal planes of an epitaxial layer are of a screw character [106,154,155]. Conversion from BPDs to TEDs is enhanced by several techniques such as molten KOH etching [156,157] or H2 etching [158] prior to epitaxial growth or growth interruption [159]. Furthermore, increasing the growth rate also effectively enhances the BPD-TED conversion [160].…”