Studies of the effects of the bore length during plasma immersion ion implantation of a small cylindrical bore with auxiliary electrode by two-dimensional fluid model

The inner surface modification of many industrial components, such as dies, bushings, pipes, etc, using plasma immersion ion implantation (PIII) has grabbed the attention of physicists and materials scientists. One drawback of the PHI modification of inner surface is low ion impact energy. It has been shown that by inserting a zero potential conductive auxiliary electrode positioned at the axis of the implanted cylindrical bore, the average ion impact energy can be raised. Plasma immersion ion implantation (PIII) of the inner surface of a finite-length small cylindrical bore with a coaxial, grounded auxiliary electrode are calculated using a two-dimensional fluid model. Various ratios of bore diameters against bore lengths are simulated. It is found that the sheath structure resulting from the auxiliary electrode focuses ions from both inside and outside the bore onto the inner surface. If the bore length is long enough, the ions from outside the bore cannot be implanted into the deeper region of the inner surface. Therefore, we can simulate the implantation of the deeper region by a one-dimensional fluid model.