Growth of Nanocrystalline Diamond Films on Poly Silicon

폴리 실리콘 위에서 나노결정질 다이아몬드 박막 성장

The growth of nanocrystalline diamond films on a p-type poly silicon substrate was studied using microwave plasma chemical vapor deposition method. A 6 mm thick poly silicon plate was mirror polished and scratched in an ultrasonic bath containing slurries made of 30 cc ethanol and 1 gram of diamond powders having different sizes between 5 and 200 nm. Upon diamond deposition, the specimen scratched in a slurry with the smallest size of diamond powder exhibited the highest diamond particle density and, in turn, fastest diamond film growth rate. Diamond deposition was carried out applying different DC bias voltages (0, -50, -100, -150, -200 V) to the substrate. In the early stage of diamond deposition up to 2 h, the effect of voltage bias was not prominent probably because the diamond nucleation was retarded by ion bombardment onto the substrate. After 4 h of deposition, the film growth rate increased with the modest bias of -100 V and -150 V. With a bigger bias condition(-200 V), the growth rate decreased possibly due to the excessive ion bombardment on the substrate. The film grown under -150V bias exhibited the lowest contact angle and the highest surface roughness, which implied the most hydrophilic surface among the prepared samples. The film growth rate increased with the apparent activation energy of 21.04 kJ/mol as the deposition temperature increased in the range of $300{\sim}600^{\circ}C$.