Optimized Substrate Orientation for 4H-SiC Epitaxy

SiC devices are limited in application due to high substrate manufacturing costs. High temperatures are required to make high quality 4H-SiC substrates, limiting throughput and imposing large maintenance costs on equipment. Lowering the process temperature will make SiC devices more economical, but difficulties with maintaining useful growth rates remain; altering CVD gas precursor chemistry alone has proved insufficient to meet the rate requirement. Substrate surface conditions in 4H-SiC have long been paramount to eliminating defects in epitaxial layers. Miscut off the [0001] surface axis is 4° in commercial production, although this was determined in an empirical trial-and-error approach; a systematic study of miscut and orientation has not been performed. Phase I will determine ideal substrate orientation for maximizing growth rate while maintaining film quality, while Phase II will scale the process for increased growth rate and larger substrates. Phase III will transition the technology to full scale production.