In situ bow reduction during sublimation growth of cubic silicon carbide

Abstract

Sublimation growth of cubic silicon carbide (3C–SiC) with diameters of 50 and 100 mm was performed on freestanding homoepitaxial grown seeds. For both seeds and sublimation grown crystals, two different relaxation axes with varying curvature could be observed with the higher bent axis aligned perpendicular to the original wafer flat. A general reduction in the wafer bow independent of the starting curvature and size of the seeds could be observed. Using the X-ray imaging, we could observe in situ that the bow reduction is linked to the growth of new material and cannot be initiated by heat up or cool down processes alone. Raman spectroscopy of the grown crystals revealed that the observed flattening goes along with a tensing of the seeding layers while the surface of the crystals remains free of a stress gradient. A slight concave bending of lattice planes along the main relaxation axis could be observed by high-resolution XRD rocking curve measurements while for the lower bent axis, no lattice plane bending occurred. Full width half maximum values of the (002) reflection showed values as low as 67 arcseconds proofing the possibility to grow large-area, high-quality 3C–SiC using sublimation growth.

Keywords

• cubic silicon carbide
• wafer bow
• sublimation growth
• stress analysis
• in situ x-ray imaging