Progress in Large-Area 4H-SiC Epitaxial Layer Growth in a Warm-Wall Planetary Reactor

Abstract

Results are presented for epitaxial SiC layers grown on 100 mm and 150 mm wafers suitable for power devices by CVD using a VP2800WW multi-wafer reactor with 10×100mm and 6×150mm configurations. We have demonstrated continuous improvement in uniformity for thickness and doping, as well as in defect reduction in standard epitaxy on 100 mm wafers. Thickness and doping sigma/mean values of <1.5% and <8%, respectively, could be routinely achieved. Doping and thickness measurements of 30 μm layer growth show results similar to standard epilayer growth. The averaged projected site yields of 80% for 5x5 mm2 and of 96% for 2x2 mm2 correspond to a low epitaxial defect density of <1 cm="" sup="">-2 in 30μm thick epilayers. Epilayer structures for bipolar devices like PiN diodes and BJTs are shown. The interface regions between nitrogen doped and aluminum doped layers show an abrupt transition of dopant concentration. Wafer quality of 100 mm and 150 mm material is presented as an important base factor for excellent epitaxial layer quality. It is shown that 150 mm substrates exhibit TSD and BPD densities very similar to the 100 mm materials. Site counts for TSDs and BPDs on sample wafers show dislocations densities of 500 cm-2 and 300 cm-2, respectively. After CVD process optimization, a thickness uniformity (sigma/mean) of <1.5% and a doping uniformity of <13% was achieved on epitaxial layers on 150mm.