Improved stabilizer design in cathodic vacuum arc discharge featuring a coiled anode for tetrahedral amorphous carbon film deposition

Tetrahedral amorphous carbon (ta-C) films, which are hydrogen-free diamond-like carbon (DLC) films with a high fraction of sp 3 bonds, exhibit high hardness and wear resistance. To form ta-C films with a small number of droplets, a high-rate filtered arc deposition system with a coiled anode (HR-FAD: Type Carbon) was developed. In HR-FAD, a plasma beam is formed when a magnetic field is applied to a coiled anode. This plasma beam has regions of high and low plasma density around it. However, as the distance between the region of high plasma density and the anode increases, the arc voltage increases, and frequent self-extinction events occur. In this study, stabilizer structures, hereafter called stabilizers, were mounted on the anode base plate to shorten the distance between the plasma and anode, thereby improving the discharge stability. Three types of stabilizers were designed and tested: a mask-type stabilizer, a protruding-type stabilizer, and a protruding L-shaped stabilizer. All the stabilizers reduced the arc voltage and self-extinction rate. The protruding L-shaped stabilizer did not reduce the deposition rate of the ta-C films. Furthermore, the long protruding L-shaped stabilizer can be used for long-term discharge and stable continuous operation of the system.