2022, Vol.32, No.1

Journal of the Korean Crystal Growth and Crystal Technology 2023 KCI Impact Factor : 0.19

pISSN : 1225-1429 / eISSN : 2234-5078
https://journal.kci.go.kr/jkcgct

In this research, a ring-shaped silicon carbide (SiC) single crystal manufactured using the PVT (Physical VaporTransport) method was proposed to be applied to a SiC focus ring in semiconductor etching equipment. A cylindricalgraphite structure was placed inside the graphite crucible to grow a ring-shaped SiC single crystal by the PVT method. SiCsingle crystal ring without crack was successfully obtained in case of using SiC single crystal wafer as a seed. A plasmaetching process was performed to compare plasma resistance between the CVD-SiC focus ring and the PVT-SiC focus ring. The etch rate of ring materials in PVT-single crystal SiC focus ring was definitely lower than that of CVD-SiC focus ring,indicating better plasma resistance of PVT-SiC focus ring.

Recently, Hanmi Gemological Institute & Laboratory (HGI) had an opportunity to examine 5 transparent syntheticmoissanite. The round brilliants ranged from 0.93 to 0.96 ct and had a colorless, pink, yellow, blue, and red color. Advancedtesting results, including Fourier-transform infrared (FTIR) and Raman spectroscopy, identified all the specimens as syntheticmoissanite. Under the microscope, all samples except the colorless were confirmed to be a synthetic moissanite coated witha colored film. EDXRF chemical analysis detected very weak X-ray fluorescence peak characteristics of Ca, Ti, and Co inthe colored samples. These features were not detected in the colorless sample. Raman spectroscopy investigation was unableto detect the 1332 cm-1(produced by sp3bonding of carbon atoms) or the ~1550 cm-1(produced by graphite-related sp2bonding) peak in the colorless sample. The SEM image of the colorless sample showed no indication of a coating. TheTEM image of the colorless sample revealed the presence of a 3~8 nm thick layer on the moissanite. Moreover, from thecorresponding STEM Z-contrast image combined with the energy-dispersive X-ray spectroscopy (EDX) line profiles andEDX elemental maps, this layer was estimated to be carbon, silicon and oxygen.

The effect of SiO2, Na2O and CaO on isokom temperatures in soda-lime glass is estimated by comparing calculated isokom temperatures using viscosity model proposed by Lakatos. The isokom temperatures at the viscosity of log η=12.3,10, 6.6 and 1 (Pa·s) are lowered by 6, 7, 10 and 24°C, respectively, by the substitution of SiO2 with Na2O by 1 mol%. Meanwhile, replacing 1 mol% of SiO2 with CaO raises the isokom temperatures by 3~4 and 2°C at the viscosity of logη=12.3 and 10 (Pa·s), respectively, but lowers the temperatures by 1 and 21°C at the viscosity of log η= 6.6 and 1 (Pa·s), respectively.