Metal Cylindrical Sieve (MCS) for plasma confinement and low sputtering nitrogen plasma immersion ion implantation

Abstract

Nitrogen Plasma Immersion Ion Implantation (N-PIII) was performed in the Metal Cylindrical Sieve (MCS) configuration that consists of Stainless Steel 308 L (SS308L) spiral spring wound wire. Two N-PIII regimes were obtained: one using a current of 5 A (with ends open), in which an intense sputtering of the wire occurs while for currents above 12 A (with one side closed), the sputtering is diminished substantially. This behavior at different powers in MCS can be explained in terms of the sheath overlapping between the spiral spring paths. The plasma density near the wire is insufficient to overcome the sheath overlapping between the spiral spring paths when the current is low, which leads to high sputtering of the wire surface. However, in high current, sheath overlapping is avoided and high ion implantation condition is achieved. FEG-SEM analyses of the silicon sample placed on the screen plate in front of MCS mouth indicated a high deposition of the sputtered material at low current in contrast with low deposition at high current. These deposition free results allow us to plan efficient N-PIII treatments of different types and sizes of metal springs, grids, rings, and wires, with high performance, for industrial and scientific applications.