Eddy‐Current Resistivity Mapping of Low‐Resistivity n‐Type 4H–SiC: Accuracy, Repeatability, and Application Relevance

We present a comprehensive evaluation of non‐contact eddy‐current resistivity mapping of low‐resistivity n‐type 4H–SiC substrates using the RESmap system from Freiberg Instruments. Precise characterization of highly doped SiC substrates is particularly challenging, as it requires accurate detection of subtle resistivity variations, identification of minor radial inhomogeneities arising from doping gradients or basal facets, and consistent measurement performance despite temperature fluctuations and rapid measurement cycles. Addressing these issues is crucial in production environments, particularly in processes such as laser separation, where even minor variations in resistivity can significantly affect splitting quality and device performance. The applied non‐contact eddy‐current resistivity mapping system uniquely integrates temperature and distance compensation, and easy‐to‐use calibration routines aligned with SEMI MF673 standards. Its robust automation capabilities further minimize manual handling, enhance throughput, and ensure long‐term stability, as confirmed by a thorough statistical evaluation across multiple operators, varying environmental conditions, and different measurement speeds. We investigated several SiC wafers and boules and presented results from two different 4H–SiC boules: one selected for its unique inhomogeneity and the other for its typical industrial‐substrate characteristics with subtle radial nonuniformities. This paper highlights the achievement of a repeatability of below 0.15%, which has not been confirmed for high conductivity samples before. It proves that such levels of accuracy can be achieved in even cases of low resistivity n‐type 4H‐SiC, which would be of great significance for substrates for power electronics.