IN-SITU EXAMINATION OF THE PLASMA PROCESSES DURING THE DEPOSITION OF HARD CARBON COATINGS FROM A LOW-PRESSURE ARE PLASMA

A low-pressure are plasma discharge from a hollow LaB6 cathode with up to 100 A discharge current is used to create plasmas of high density. The configuration of the magnetic field allows a homogeneous distribu tion of the plasma density in front of the substrate surface. Typical values for the electron density and temperature in the PETRA facility (Plasma Engineering and Technology Research Assembly) are n(e)=10(12)- 10(13) cm(-3) in the region of high plasma density and up to 10(11) cm (-3) in front of the substrate surface. The electron temperature is T- e=5-20 eV. The ionization ratio is typically 1-10%. In this facility, amorphous carbon films were deposited on Si(100) substrates by admirin g CH4 and C2H2 to He plasmas. The deposition rate reached to date is 1 mu m per 10 min. During the deposition, local measurements with elect ric double probes were performed to determine the spatial distribution of the electron density and electron temperature. In addition, mass s pectroscopy of the neutral gas was performed to investigate the dissoc iation of the hydrocarbon precursors and to measure the amount of libe rated hydrogen. After the experiments the carbon deposits were examine d with regard to film homogeneity and film morphology as determined by SEM and Raman spectroscopy.