Three-dimensional curving of crystal planes in wide bandgap semiconductor wafers visualized using a laboratory X-ray diffractometer

Abstract

The curving of crystal planes (CCP) in wide bandgap semiconductor wafers, caused by thermal stress during crystal growth or wafer planarization processes, poses serious problems in subsequent epitaxial growth and device fabrication; therefore, it requires a precise assessment. In this paper, we report a method for visualizing the CCP in three-dimensional space using a laboratory X-ray diffractometer. The characteristic CCP is presented for 4H-SiC, GaN, AlN, and β-Ga2O3 commercial substrates with widely varied size and thickness, surface orientation, surface treatment, dopant species, and dislocation density. The results will aid crystal growers in gaining an overview regarding the shape of the CCP (e.g., convex or concave, isotropic or anisotropic) and the radius of curvature in these up-to-date power semiconductor wafers. The method can be used to optimize crystal growth conditions and wafer planarization processes.