Selective Epitaxial Growth of 4H-SiC with SiO2 Mask by Low-Temperature Halo-Carbon Homoepitaxial Method

Abstract

Previously reported CVD epitaxial growth of 4H-SiC at temperatures down to and below 13000C using CH3Cl precursor offered a promise of new device applications that could benefit from lower-temperature growth process. In this work, selective epitaxial growth (SEG) of 4H-SiC mesas using conventional SiO2 low temperature mask is reported. Virtually no nucleation on the mask could be observed after SEG at 13000C. The mask could be easily removed after the growth, with no degradation of the surface of SiC substrate under the mask. For the growth conditions that normally resulted in growth rate of 2 /m/hr and defect-free epilayer morphology during regular full-wafer (non-SEG) epitaxy, the epilayer morphology during SEG was significantly degraded by the appearance of oriented triangular defects, while the growth rate increased more than three times in comparison to the blanket epitaxial growth due to the loading effect. The growth at optimized growth conditions and lower growth rate resulted in significant reduction of the surface defects, making this approach promising for obtaining device-quality mesas. The crystal quality of the mesas, defects at the mesa walls, formation of facets during SEG, and other effects are reported.