Reduction of background carrier concentration and lifetime improvement for 4H-SiC C-face epitaxial growth

Abstract

Reduction of background carrier concentration was investigated for 4H-SiC C-face epitaxial growth in order to realize ultrahigh-voltage power devices. The quantitative contribution of each epitaxial growth parameter was studied, and it has been found that the growth rate increase and the pressure decrease were more effective than the C/Si ratio. Optimizing the parameters has made it possible to achieve a background carrier concentration of 7.6 × 1013 cm−3 within the whole area of specular 3-in. wafers. In addition to the background carrier concentration reduction, it has been confirmed that small epitaxial film thickness variation, low surface defect density and carrier lifetime fulfill the requirements for the devices. Moreover, in-process propane annealing has been found effective in improving the carrier lifetime. As a result, the longest lifetime value to date of 1.6 µs was obtained for a C-face epitaxial film.