Continuous Growth of Buffer/Drift Epitaxial Stack Based on 4H-SiC by Quick Change of N2 Flow Rate under High Growth Rate Condition

N-type 4H-SiC homo-epitaxial films were grown under high growth rate condition by high speed wafer rotation vertical CVD tool, and dependence on N2 flow rate for in-wafer distribution of thickness and carrier concentration was investigated. By adjusting only the N2 flow rate from 0.33 to 130 sccm, average carrier concentration of the SiC film was controlled within a range from 3 x 1015 to 1 x 1018 cm-3, while maintaining good in-wafer uniformity less than ±7.0%. Average growth rate higher than 54 μm/h and in-wafer uniformity less than ±3.1% were maintained and no dependence for thickness distribution on N2 flow rate was observed. Buffer/drift epitaxial stack using quick change of N2 flow rate was fabricated, and the crystalline quality and steepness of N concentration at buffer/drift interface were also investigated. The epitaxial stack showed lower defect density compared with single drift layer and showed steep interface between buffer layer and drift layer.