Influence of RF ICP PECVD process parameters of diamond-like carbon films on DC bias and optical emission spectra

The work presents the results of a research carried out with PlasmaLab Plus 100 system, manufactured by Oxford Instruments Company. The system was configured for deposition of diamond-like carbon films by ICP PECVD method. The change of an initial value of DC bias was investigated as a function of set values of the generator power (RF generator and ICP generator) in the constant power of the RF generator operation mode. The research shows that the value of DC bias nearly linearly depends on the RF generator power value and is affected only in a small degree by the power of ICP discharge. The capability of an installed OES spectrometer has been used to ensure the same starting conditions for the deposition processes of DLC films. The analysis of OES spectra of RF plasma discharge used in the deposition processes shows that the increase in ICP discharge power value results in the increased efficiency of the ionization process of a gaseous precursor (CH4). The quality of deposited DLC layers was examined by Raman spectroscopy. Basing on the acquired Raman spectra, the theoretical content of sp3 bonds in the structure of the film was estimated. The content is ranging from 30% to 65% and depends on ICP PECVD deposition process parameters.