Papers by Author: Chang Hyun Son

Abstract: The effect of slurry composition and wafer flatness on a material removal rate (MRR) and resulting surface roughness which are evaluation parameters to determine the CMP characteristics of the on-axis 6H-SiC substrate were systematically investigated. 10 x 10 mm2 6H-SiC substrates and 2-inch SiC wafers fabricated from the ingot grown by a conventional physical vapor transport (PVT) method are used for this study. The SiC substrate after the CMP process using slurry added oxidizers into slurry consisted of KOH-based colloidal silica and nano-size diamond particle exhibited the significant MRR value and a fine surface without any surface damages. SiC wafers having high bow value after the CMP process exhibited large variation in surface roughness value compared to wafer with low bow value. The CMP-processed SiC wafer having a low bow value of 10m was observed to result in the MRR value of 0.15 m/h and the mean height (Ra) value of 0.772Ǻ.

Abstract: Two SiC single crystal ingots were prepared using sublimation PVT techniques through the different process procedure and then their crystal quality was systematically compared, because the present research was focused to improve the quality of SiC crystal by modifying the initial stage of the PVT growth. Before the main growth step for growing SiC bulk crystal, initial stage period where growth rate was kept to relatively low rate of <10μm/h was introduced to conventional process procedure. N-type 2”-SiC single crystals exhibiting the polytype of 6H-SiC was successfully fabricated. As compared to the characteristics of SiC crystal grown using the conventional schedule, the quality of SiC crystal grown with modifying the initial stage was significantly improved, exhibiting decrease of defect formation such as micropipe and polytype formation.