Study on Estimation of Device Yield in Non-Epitaxial 4H-SiC Material Relating to Defect Densities Influencing Bipolar Degradation with XRT- Measurements

Commercially available 4H-SiC substrate quality has improved over time, and this has extensively reduced defect concentrations in the active epitaxial layer, during epi growth conditions at the interface. The objective of this work is to investigate bulk crystal quality for the purpose of future vertical power device fabrication in exfoliated, non-epitaxial, undoped material layers.Mathematical estimations on the device yield fraction, that is immune to bipolar degradation for the suggested future process were calculated based on XRT measurements to detect BPD and TSD densities on donor substrates. The full wafer BPD density maps of on-axis semi-insulating wafer substrates from two vendors were compared.