Vapor phase 6H and 4H SiC epitaxy for high-speed devices

Abstract

Silicon carbide (SiC), a wide bandgap semiconductor, is currently being developed for enhanced high-power and high-temperature microwave devices. Silicon carbide wafers, now available at up to two-inch diameter with resistivities from 0.02 /spl Omega/-cm to 10/sup 7/ /spl Omega/-cm, still exhibit features such as micropipes, surface scratches, and inclusions of other polytypes. Vapor phase epitaxy (VPE) of 6H and 4H SiC, typically performed between 1450 and 1600/spl deg/C using silane and propane reagents, is impacted greatly by the quality of these wafers and the conditions used during in situ etching or the initial stages of growth. By optimizing growth conditions, device-quality homoepitaxial 6H and 4H-SiC has been grown with near specular morphology, background doping levels of less than 1/spl times/10/sup 14/ cm/sup -3/, and controlled n- and p-type doping from less than 5/spl times/10/sup 15/ cm/sup -3/ to greater than 1/spl times/10/sup 19/ cm/sup -3/.