Reduction of Pinhole Defects in DLC Film Prepared with Plasma-based Ion Implantation and Deposition

Abstract

Diamond-like carbon (DLC) films were prepared on the SUS304 substrate with a hybrid process of plasma-based ion implantation and deposition using toluene plasma. The pinhole defects in DLC films reached to the substrate deteriorate corrosion resistance. The area ratio of pinhole defects to the bare substrate was evaluated by the critical passivation current density (CPCD) method. The CPCD measurement indicated that the area ratio of pinhole defects in the DLC film was decreased with increasing film thickness and reached to about 1 x 10^-3 % at more than 6 micro m in thickness. The apparent area ratio of pinhole defects were also reduced by the interfacial treatment before DLC deposition such as the production of an interfacial mixing layer by carbon ion implantation to the substrate or the formation of SiCx nanolayer in front of substrate in the thinner film thickness. The ultrasonic cleaning in the acetone during the deposition reduced the area ratio of pinhole defects to 6 x 10^-4 % at the DLC film thickness of 1 micro m.