Optimization and Simulation on Gas Flow and Temperature Fields on the Homoepitaxial Growth of N-Doped 4H-SiC Wafers

The uniformity of nitrogen (N) doping concentration in 4H-SiC epitaxial wafers is a critical determinant of electrical consistency and device reliability. In this study, key chemical vapor deposition (CVD) growth parameters, including the C/Si ratio, H₂ carrier gas flow rate, flow split ratio, and growth temperature, were systematically adjusted to investigate their effects on the N doping concentration and uniformity of 6-inch 4H-SiC homoepitaxial layers. The relationships between these parameters and characteristic phenomena such as site-competition epitaxy, along-track depletion of carbon source, and the distinct "W-shaped" doping profile were comprehensively analyzed. Furthermore, simulations of the flow and temperature fields within the reaction chamber and across the SiC epitaxial wafer revealed that under optimized conditions a stable parallel flow field forms above the wafer, accompanied by a uniform temperature distribution, thereby creating an ideal environment for homogeneous N doping. This work provides both theoretical insight and practical guidance for enhancing doping uniformity in large-size SiC epitaxial wafers.