Effects of the auxiliary electrode radius during plasma immersion ion implantation of a small cylindrical bore

Summary form only given, as follows. Plasma immersion ion implantation (PIII) has a number of advantages over conventional beam-line ion implantation techniques. One of them is the ability to implant "interior" surfaces that are not line-of-sight accessible. The inner surfaces of many industrial components, such as dies, bushings, pipes, and so on are difficult to process and inner surface modification using PIII is both interesting scientifically and commercially. We have proposed a method to improve the impact energy of ions implanted into the interior sidewalls of cylindrical specimens by using an auxiliary electrode having a zero potential. The ion-matrix sheath and the temporal evolution of the plasma sheath in a small cylindrical bore with an auxiliary electrode have been calculated for an auxiliary electrode of a regular radius. In this paper, the effects of the auxiliary electrode radius are discussed. We compute the critical radius of the cylindrical bore when the ion-matrix sheath just overlaps as well as the number of implanted ions. The ion density, flux, dose, energy, energy distribution, and average impact energy are also determined for different radii of the auxiliary electrode by solving Poisson\´s equation and the equations of ion continuity and motion numerically. Our results provide the theoretical background for the implementation of an auxiliary electrode in a PIII instrument.