Effects of Electron Focused Electric Field upon Enhanced Glow Discharge Plasma Ion Implantation

Plasma immersion ion implantation (PIII) has been widely used in the modification of materials such as metal, plastics, and ceramics to improve mechanical properties such as wear, corrosion, fatigue and friction. In typical PIII, the samples are immersed in an overlying plasma and pulse-biased to a high negative voltage to carry out ion implantation. PIX has many advantages compared to conventional ion implantation, for example, the obviation of an accelerator, parallel implantation into all surface, and high efficiency. However, the process requires external plasmas ignited by methods such as RF, microwave, vacuum arc, hot filaments. These plasma-making methods usually have their own intrinsic advantages and disadvantages. In addition, these plasma sources add to the cost.


Here, we introduce a new method called Enhanced Glow Discharge Plasma Ion Implantation (EGDPII) which does not require external plasma sources. In this technique, the plasma is produced by the self glow discharge due to the high negative voltage bias. The small-area, pointed-shape hollow anode and large area tabular cathode form an electron-focused electric field. Using a special electric field design, the electrons from either the plasma or target (secondary electrons) are all focused to a special hollow anode. By using the special electron-focusing field, the self-glow discharge process can be enhanced to achieve effective ion implantation into the substrate. The patterns of the equipotential lines and electric fields are calculated by the finite-element method. Our results show that by using the special electron-focusing field, self glow discharge is enhanced and a higher ion density can be attained for more efficient plasma implantation.