Spatial variation of lattice plane bending of 4H-SiC substrates

Abstract

Basal plane bending of on- and off-axis 4H-SiC substrates was measured by high-resolution X-ray diffractometry (HRXRD). In order to evaluate basal plane bending properties in detail, line scans of 0004 reflection rocking curves were carried out on the (0001) Si face along the <110>, <100>, <20>, <100>, <110> and <010> directions. The silicon face of unintentionally doped 4H-SiC substrates is not a flat plane. One of them has a “basin”-like concave bend and the other has a “spherical” concave bend. The silicon face of on-axis n-type SiC is also not flat, but approximately convex “spherical”. In contrast, the silicon face of off-axis n-type SiC is “saddle”-like. Bending inheritance of unintentionally doped 4H-SiC and the effect of annealing and corrosion on their bending properties were studied. Molten KOH defect selective etching was carried out to understand the mechanism responsible for the bending. Finally, the effect of single crystal-growth thermal field and structural defects on basal plane bending of the substrates were explored.