Studies on Selective Growth and In Situ Etching of 4H-SiC Using a TaC Mask

Abstract

We have previously reported on the selective growth of 4H-SiC epitaxial layers on a 4HSiC substrates in a chemical vapor deposition (CVD) reactor using TaC mask. It was shown that pn junctions fabricated using selectively grown n-layers on trench etched p-substrates have properties similar to the mesa etched pn junction diodes, indicating good interface properties. In this paper, we present more systematic studies on the selective growth and in-situ selective etching of 4H-SiC using a TaC mask. The morphological evolution during selective epitaxy as a function of crystallographic orientation was analyzed. Anisotropy in surface morphology along <11-20> and <1-100> has been observed. Cross sectional SEM viewgraphs show lateral overgrowth on the TaC mask, and the extent of lateral overgrowth varied with the stripe orientation. It was found that the “growth window” for selective growth was a function of the surface area covered by the TaC mask as well as the window opening to mask width ratios. Experiments with various window widths to mask width ratios have been carried out to investigate the selective growth process using this mask.