Characterization of Defects in the Expanded Area of Large-Size 8 Inch 4H-Sic Single Crystal Substrates

Silicon carbide (SiC), widely regarded as an optimal material for third-generation semiconductors, is valued for its exceptional physical properties suitable for high-temperature, high-frequency, high-voltage, and high-power devices. However, the costly SiC substrates hinder their widespread adoption. Large-sized 4 H-SiC single crystal substrates, grown using the physical vapor transport (PVT) method and diameter expansion technology, offer a potential solution to reduce costs and are crucial for advancing SiC -based power devices. Various characterization techniques, including optical microscopy, high-resolution X-ray diffraction analysis, polarization stress measurement, and dislocation testing, were used to compare defects between expanded and non-expanded areas on a 192 mm 4 H-SiC substrate. Results show that the expanded area had significantly higher micropipe density (5.22 / cm 2), a larger full width at half maximum (FWHM) value of 44.6 arcsec, indicating poorer crystallization quality, along with more prominent stress lines and concentrated dislocations compared to the non-expanded area. Additionally, polycrystals were observed at the junction between these regions, further compromising crystalline quality. Continuous optimization of growth processes and iterative improvements in crystal growth techniques led to the successful production of an 8 -inch 4 H-SiC substrate with minimal resistivity variations across its surface and an extremely low density of dislocation micropipes.