Deposition of nanoscale metal films with the help of arc discharge

Abstract

The method of magnetron sputtering using arc discharge is one of the most advanced and high-performance techniques for producing nanoscale films, especially metal films and, in particular, titanium and copper ones. The cathode spots that form during arc discharge are the discharge centers and they provide channels along which current travels from the cathode to the anode in the form of dense plasma jets of the cathode material forming a so-called plasma torch. The ion energy in such plasma torch is higher than in the conventional magnetron sputtering, which ensures a significantly better adhesion of the resulting films. At the same time, nanoscale titanium films are often used to create transition mating sublayers between the substrate and the main working film. Out of non-metallic films, titanium nitride films are of special interest. The main disadvantage of magnetron arc sputtering is the presence of a droplet phase in the plasma torch, which hinders the creation of nanoscale structures by forming condensate on the substrate. The resulting microdroplets are usually electrically neutral, therefore they cannot be removed and neutralized by means of electric or magnetic fields. The arc evaporator needs to be retrofitted so that the droplet phase was eliminated and thin-film coatings (including nanoscale coatings) could be produced. A plasma torch is formed with the help of a focusing coil, in which both ions of the sprayed substance and its droplets are present. A special flap prevents direct-flying droplets from getting in the flow of sprayed substance, and at least one more flap installed in the housing of the focusing coil protects the flow from droplets flying at an angle from the cathode. The flap is designed as a truncated cone made of non-magnetic metal, with the diameter of the larger base of the cone being equal to the inner diameter of the focusing coil, and the smaller diameter of the cone that faces the cooled cathode is equal to twice the diameter of the flap. The flap is coaxial with the cooled cathode of the arc evaporator.