Basal Plane Dislocation Mitigation in SiC Epitaxial Growth by Nondestructive Substrate Treatment

Abstract

An optimized molten KOH−NaOH−MgO eutectic mixture is used to pretreat the 8°off-axis 4H-SiC substrate prior to chemical vapor deposition epitaxial growth. Superior to the conventional pure KOH etching method, by way of the eutectic method, the conversion of basal plane dislocation (BPD) to threading edge dislocation in the subsequent epitaxial growth is independent of the etch pit size pregenerated on the substrate. Even with a very mild treatment using the eutectic mixture, which does not generate discriminable etch pits on the substrate, an epilayer with low BPD density <22 cm −2 (<0.1% of BPDs on the substrate) is still achieved, and further, there is no degradation of morphology on the entire sample surface. All of the BPD conversions occur at the initial stage of epitaxial growth.

Wide-bandgap semiconductor materials: For their full bloom

“…93) Hence, the propagation of BPDs from the substrate to the epilayer should be avoided. [94][95][96] There are still many unclear points in the behavior and control of the above defects, and they are important issues to be addressed in order to improve device performance in the future. For details, readers are referred to Ref.…”

Reaction pathway analysis for the conversion of perfect screw basal plane dislocation to threading edge dislocation in 4H-SiC

“…[9][10][11] Since unconverted BPDs propagate into the epitaxial layer, [12][13][14] many researchers have investigated increases in BPD-TED conversion ratios. For instance, the following methods have been proposed to increase the conversion ratio: the formation of etch pits using a chemical solution prior to epitaxy, [15][16][17][18][19][20] the formation of a surface pattern using plasma etching prior to epitaxy, 21) the interruption of epitaxial growth, 22,23) the use of H 2 etching, 24) the increase of the C/Si ratio, 25) the increase of the growth rate, 26,27) the reduction of the off-cut angle of the substrate, 25,28) the use of chemical mechanical polishing (CMP) to obtain a flat substrate surface, 26) and the use of thermal annealing. 29) However, since the BPD-TED conversion rate still has not reached 100% with any of these methods, further studies are required.…”