Characterization and performance of a high-current-density ion implanter with a magnetized hollow-cathode plasma source

Abstract

In a current collaboration between the Institute of Electrophysics (IEP) and the Los Alamos National Laboratory (LANL), the IEP is developing an industrial scalable, high-power, large-area ion source for the surface modification of materials. The principle set-up of the ion beam source as well as some electrical characteristics (gas discharge current and the extracted ion beam current) are presented for a Lab-scale prototype. The first results of some surface modification experiments are given, which have been performed with the lab-scale prototype at LANL. The plasma source of the ion beam source can be described as a pulsed glow discharge with a cold, hollow-cathode in a weak magnetic field. Extraction and focusing of positive ions by an acceleration and an ion-optical plate system renders the generation of a homogeneous, large-area ion beam with an averaged total ion current of up to 50 mA at acceleration voltages of up to 50 kV. By using a cold-cathode reactive gases can also be used in the discharge. Measurements of the ion current densities as function of the radial position within the beam are presented for various discharge parameters result in a fairly homogeneous ion beam over a large-area cross section of ca. 100 cm/sup 2/. Results on surface modification by ion implantation of nitrogen into aluminum and chromium are presented. Finally, a comparison of the calculated ion dose (from measurements of the ion current density) with the retained ion doses (determined by RBS of the implanted samples) is given.