Particle-in-cell/Monte Carlo simulation for PBII processing of a trench shaped target and a cylindrical target

Abstract

In order to analyze the plasma behavior in the plasma immersion ion implantation and deposition (PIII&D) process, a simulation has been carried out using the simulation software “PEGASUS”. The software uses a particle in cell method for the movement of charged particles in the electromagnetic field and a Monte Carlo method for collisions of ions, electrons, and neutrals in the plasma. The spatial distributions of potential, density, average temperature, velocity and flux of ions and electrons in the surroundings of a trench shaped target and a cylindrical target which is immersed in Ar plasma have been calculated together with the flux of ions and electrons on the target surface. The gas pressure was 0.01–600 Pa and a negative pulse, DC, RF, and RF+DC voltage (up to −20 kV) was applied to the target. The time dependence of the sheath length on the outer surface of the target agreed with the analytical values obtained by the Child–Langmuir method. In order to show the effectiveness of a bipolar pulse PIII/D process, a glow discharge plasma generation by a positive and a negative pulse voltage (± kV) application to a target were simulated and compared. The plasma generated by a positive pulse voltage was about two orders more intense than a negative pulse voltage. Furthermore, a hollow cathode discharge plasma can be applied to the inner coating of the target. The effects of gas pressure, secondary electron emission coefficient, and the length and the inner diameter of target on the plasma generation in the surroundings of a cylindrical target were studied. Paschen-like curves for a hollow cathode discharge were obtained for both centimeter-size pipe and millimeter-size pipe.