Gas Barrier Properties of Diamond-like Carbon Films Synthesized by Using Remote Type Microwave Plasma CVD under Sub-ambient Atmospheric Pressure

Diamond-like carbon (DLC) films were synthesized on polyethylene (PE) substrates with a remote type microwave plasma chemical vapor deposition (MPCVD) apparatus at 10 kPa. We investigated the effect of source gas flow rate and microwave power on oxygen transmission rate of DLC films. Acetylene (C2H2) and argon (Ar) gas were used for source gas and carrier gas, respectively. From the result of contact-type profiler and atomic force microscope, oxygen transmission rate decreased as thickness increased and surface roughness decreased with increasing C2H2 flow rate. The oxygen transmission rate of DLC film synthesized at the C2H2 flow rate of 0.50 l/min and the microwave power of 1.0 kW on 300 μm thick PE substrates was 141 cc/m2·day, while that of uncoated PE substrates was 247 cc/m2·day.