EFFECT OF NEGATIVE DC BIAS VOLTAGE ON MECHANICAL PROPERTY OF A-C-H FILMS DEPOSITED IN ELECTRON-CYCLOTRON-RESONANCE PLASMA

Amorphous C:H films were deposited with CH4-Ar-H2 using a chemical vapor deposition apparatus assisted by electron cyclotron resonance plasma. The effects of applying negative dc bias voltage on the mechanical property and the microstructure of the films were examined. The microhardness of the films increased rapidly at a threshold value of the bias voltage at each gas ratio, [Ar]/([Ar]+[H2]). The results obtained from Raman spectroscopy suggest that the films contain diamondlike structure added to polymer structure over the threshold value on the negative dc bias voltage. Although the dc bias voltage required to form diamondlike carbon (DLC) becomes stronger with the increase in the H2 flow rate, the approximate volume fraction of DLC in the films rapidly increases, implying that hydrogen is more effective to synthesize DLC films. © 1995 American Institute of Physics.