DIAMOND-LIKE CARBON-FILMS GROWN IN A NEW CONFIGURATION FOR FILAMENT ENHANCED PLASMA-ASSISTED CVD

In earlier work, we have shown that in filament-enhanced plasma assist ed CVD, increasing the degree of ionisation, reducing the voltage appl ied to the cathode and reducing the C/H ratio in the plasma produces i mproved DLC films giving a higher optical band gap and a lower hydroge n content. In that work the possibility of increasing the level of ion ization was limited. We describe here an improved discharge layout whi ch can provide specimen (cathode) current densities several orders of magnitude higher, across a wider pressure range. This produces films w ith a hardness of over 8000 HK (200 g) at a deposition rate of 2-3 mu m/h on stainless steel and mild steel, in a methane/hydrogen plasma co ntaining 0.5-1.0% methane. The morphology of the film surface is facet ed, smoother than as-deposited films reported elsewhere, but reminisce nt of those smoothed by post-deposition argon bombardment.