Dynamic MC simulations of diamond-like carbon film synthesis by plasma-based ion implantation

By plasma-based ion implantation (PBII) such as low-energy ion beam implantation in plasma, ion beam assisted deposition, and plasma immersed ion implantation, a diamond-like carbon (DLC) film is synthesized. The structure of the DLC film can be characterized by the hydrogen concentration and the relative fractions of sp2- and sp3-bonded carbon. The energy of the impinging ion plays a crucial role for the film structure and thereby the mechanical, electrical and optical properties of the film. Dynamic Monte Carlo simulations with the binary collision approximation have been applied to the synthesis of DLC films by PBII. It was assumed that energetic CH3+ ions and CH3 radicals are incident on the surface alternately. The incident molecular ions dissociated into its individual atoms when colliding with the surface. The radicals adsorbed on the surface are dissociated by the binary collisions with the impinged atoms and a part of hydrogen atoms are released from the surface. It is assumed that only the atoms receiving enough energy to overcome the surface barrier enter the solid. Release of the displaced hydrogen atoms after the subsequent collision cascade is also assumed. The relative fraction of carbon atoms in the sp2 and sp3 state were estimated by setting different displacement threshold energy for each state. Effects of the ion/neutral arrival ratio and the ion energy on the deposition rate and on the depth profile of the hydrogen content and the sp3/sp2 ratio in the deposited film are presented.