Quantification and improvement of doping uniformity on CVD grown 4H-SiC superjunction structures

A quantitative analysis of 4H-SiC superjunction reveals a variation up to three orders of magnitude of Al distribution in the p-type column, indicating a uniformity value of 128% (σ/mean percentage). Since a strong incorporation tendency of residual N2 was observed on the (1–100) m-plane, with levels exceeding those of Al dopant, nitrogen is considered a suitable dopant to ensure n-type doping across various trench positions. Thus, the conventional fabrication sequence—forming n-type trench prior to p-type epilayer—was reversed: the n-type epilayer was grown on a p-type trench, resulting in an improved doping uniformity showing a value of 49%.