Numerical Simulation of Metal Plasma Immersion Ion Implantation and Deposition (MEPIIID) on a Sharp Cone and a Fine Tip

Summary form only given. Previously, a two dimensional particle-in-cell simulation in r-z cylindrical coordinates was used to model metal plasma-immersion ion implantation and deposition (MePIIID) on a cone. It showed that a sharp cone mounted on a plane or stage exhibits an ion focusing effect. This focusing effect was due to the shape of the equilibrium sheath and is strongly enhanced by sharper cones. The focusing effect increased for sharper cones and the ion trajectories bent more sharply. The ion dose showed a sharp decrease near the cone tip. However, the tip of the cone was described by only one single point. The electric field of this point was approximately calculated by first order finite difference. In our earlier work, we could not determine whether the sharp decrease in dose was an artifact or real. We can now resolve this problem, by applying a multiple-grid method to numerically simulate the MePIIID on a sharp cone and a fine tip. A multiple-grid system with three different sizes of cells, 2 mm, 1 mm, and 0.5 mm is used in the simulation. The tip of the cone is represented by a sphere, of variable radius, in tangential contact with the edge of the cone. It shows that the highest dose located the center of the tip and we conclude that the sharp decrease in dose in our previous work was an artifact of the single point