증착조건에 따른 극미세 다이아몬드상 카본 박막의 탄성률 변화거동

The elastic modulus and the structural evolution were examined with the film thickness in polymeric, hard, graphitic diamond-like carbon(DLC) films. The DLC films used in the present study were prepared by radio frequency plasma assisted chemical vapor deposition (r.f.-PACVD) from C6H6 and CH4 gas. Elastic modulus of very thin DLC film was measured by free overhang method. This method has an advantage over the other methods. Because the substrate was removed by etching technique, the measured value is not affected by the mechanical property of the substrate. The structural evolution was investigated by the G-peak position of the Raman spectrum. The polymeric and graphitic films exhibited the decreased elastic modulus with decreasing film thickness. In polymeric films, the reason was that more polymeric film had been deposited in the initial stage of the film growth and in graphitic film more graphic films which had been deposited in the initial stage decreased the elastic modulus. The G-peak position of the Raman spectrum confirmed this result. On the other hand, the hard film showed the constant elastic modulus regardless to the film thickness. The structural change was not observed in this range of the film thickness.