PC based numerical simulation of plasma source ion implantation

Summary form only given, as follows. Plasma source ion implantation is a non-line-of-sight method for implanting ions in a material. The target is immersed in a plasma and a large negative voltage pulse is applied; a sheath following the shape of the object forms and accelerates ions into the target. A numerical simulation model has been developed for studying the expansion of the sheath, the current to the target, and the energy spectrum of the ions hitting the target. The model is one-dimensional (planar, cylindrical, or spherical) and treats the ions as a collisionless zero temperature fluid which is accelerated by the electric field. The electrons are assumed to obey the Boltzmann relation instantaneously. The ion fluid motion is solved in Lagrangian coordinates and transformed to a fixed coordinate system for the solution of Poisson´s equation. The resulting computer code runs satisfactorily on PCs. Results for the position of the edge of the expanding sheath and the current waveform have been compared to results from experiments and from a model which considers the sheath to instantaneously satisfy the Child-Langmuir law