FUNDAMENTAL ASPECT AND BEHAVIOR OF SATURATED FLUOROCARBONS IN GLOW-DISCHARGE IN ABSENCE OF POTENTIAL SOURCE OF HYDROGEN

The glow discharge of a series of saturated fluorocarbons, CnF2n+2 (n = 1, 2, 4, 6, and 8), was studied with glass substrates which do not contain any hydrogen. It was found that the deposition rate was a function of the F/C ratio of the starting fluorocarbons. That is, fluorocarbons with higher F/C ratio, such as CF4 and C2F6, hardly polymerized, while fluorocarbons with lower F/C ratio, such as C8F18, polymerized as well as C2F4. After plasma exposure, the surface of glass substrate was characterized by measurements of water contact angle, water droplet rolling-off angle, and ESCA. Although all saturated fluorocarbon plasmas could alter the surface more hydrophobic than before, the deposited materials from fluorocarbons with higher F/C were not stable. Also, in plasmas with high F/C fluorocarbons, i.e., CF4 and C2F6, sputtering of the electrode material was observed.