Porous SiC Substrate Materials for High-Quality Epitaxial and Bulk Growth

Abstract

The main unsolved problem in SiC technology is a high density of defects in substrate materials (micropipes and dislocations) propagating into device structures and causing device failure. Recently, significant progress in defect density reduction in semiconductor materials has been achieved using epitaxial lateral overgrowth techniques. In this paper, we describe a novel technique, which shows a high potential for defect reduction in epitaxial and bulk SiC. This technique is based on nano-scale epitaxial lateral overgrowth (NELOG) method, which employs porous substrate materials. Usually, the pores are from 50 to 500 nm in size and epitaxial material overgrowing these pores, forms continues high-quality layer. It is important that the NELOG method does not require any mask. This technique may be easily scaled for large area substrates.

In this work, SiC layers were grown on porous SiC by sublimation method, which is widely used for both epitaxial and bulk SiC growth. Porous SiC substrates were formed by surface anodization of SiC commercial wafers. It was shown that SiC layers grown on porous SiC substrates have smooth surface and high crystal quality. The surface of overgrown material was uniform and flat without any traces of porous structure. X-ray topography indicated significant defect density and stress reduction in SiC grown on porous material. Photoluminescence measurements showed a reduction of deep level recombination in SiC.