Initial results are presented for SiC-epitaxial growths employing a novel 6x150-mm/10x100-mm Warm-Wall Planetary Vapor-Phase Epitaxial (VPE) Reactor. The increased areal throughput offered by this reactor and 150-mm diameter wafers, is intended to reduce the cost per unit area for SiC epitaxial layers, increasing the market penetration of already successful commercial SiC Schottky and MOSFET devices [1]. Growth rates of 20 micron/hr and short <2 hr fixed-cycle times (including rapid heat-up and cool-down ramps), while maintaining desirable epitaxial layer quality were achieved. No significant change in 150 mm diameter wafer shape is observed upon epitaxial growth consistent with good-quality, low-stress substrates and low (<5°C) cross-wafer epitaxial reactor temperature variation. Specular epitaxial layer morphology was obtained, with morphological defect densities consistent with projected 5x5 mm die yields as high as 80% and surface roughness, Ra, of 0.3 nm. Intrawafer thickness uniformity is good, averaging only 1.6% and within a run wafer-to-wafer thickness variation is 2.7%. N-type background doping densities less that 1E14 cm-3 have been measured by CV. Doping uniformity and wafer-to-wafer variation currently average ~12% requiring further improvement. The first 100 m thick 150-mm diameter epitaxial growths are reported.

The polytype and surface and defect microstructure of epitaxial layers grown on 4H(1120), 4H(0001) on-axis, 4H(0001) 8°off-axis, and 6H(0001) on-axis substrates have been investigated. High-resolution x-ray diffraction (XRD) revealed the epitaxial layers on 4H(1120) and 4H(0001) 8°off-axis to have the 4H-SiC (silicon carbide) polytype, while the 3C-SiC polytype was identified for epitaxial layers on 4H(0001) and 6H(0001) on-axis substrates. Cathodoluminescence (CL), Raman spectroscopy, and transmission electron microscopy (TEM) confirmed these results. The epitaxial surface of 4H(1120) films was specular with a roughness of 0.16-nm root-mean-square (RMS), in contrast to the surfaces of the other epitaxial layer-substrate orientations, which contained curvilinear boundaries, growth pits (~3 · 10 4 cm )2 ), triangular defects >100 lm, and significant step bunching. Molten KOH etching revealed large defect densities within 4H(1120) films that decreased with film thickness tõ 10 6 cm )2 at 2.5 lm, while cross-sectional TEM studies showed areas free of defects and an indistinguishable film-substrate interface for 4H(1120) epitaxial layers.

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