Theoretical investigation of the effects of AC applied voltage on film unformity in dual plasma deposition

Dual plasma depsition incorporating gaseous plasma and vacuum arc plasma is a useful method to synthesize thin films. Although the gaseous plasma density is quite uniform in the vacuum chamber, the density of the output of a vacuum are plasma source is much less uniform in both the radial and axial directions. At the same time, since ions emitted from a vacuum arc plasma source have high axial velocity, the radial plasma density cannot be easily changed. As a result, it is difficult to perform large area deposition/implantation uniformly. In order to improve the uniformity of the plasma density, we apply an AC voltage onto the substrate. When the applied voltage is positive, the ion velocity is reduced and the plasma becomes more uniform due to diffusion and the radial velocity of the incoming ions. In our particle-in-cell (PIC) simulation, we set the negative voltage and pulse width to predefined values according to the radial ion velocity to investigate the effects of the positive applied voltage, positive voltage pulse width, and the distance of the substrate on the uniformity of the deposited film. Our simulation results clearly demonstrate that a proper AC voltage can improve the uniformity of the thin film.