Ion implantation by vacuum arc plasmas

Abstract

Plasma immersion ion implantation (PIII) is a promising new method to modify surfaces of materials by ion implantation. PIII works without expensive accelerators and therefore this method should have the potential for more applications than conventional ion accelerators. By this method, the samples are immersed into a plasma and high voltage pulses are applied to it for extracting ions from the plasma. Neither an extraction system nor other ion optics are needed. In addition to this great advantage, by using PIII, higher ion current densities and shorter implantation times are possible. The most commonly used plasma immersion arrangements extract the ion current from excited gases, especially from nitrogen. The vacuum arc is an option to produce hydrogen-free carbon plasmas or metal vapor plasmas. These plasmas extend the possibilities of the immersion ion implantation considerably. For an efficient use of PIII in thin film technology, ion sources with currents higher than 1.0 A are necessary. Moreover, the source has to be a compact tool. We have developed an ion source based on a pulsed high current arc. For the separation of the macroparticles, a magnetic plasma filter is used. The efficiency of the system was proved by implantation of carbon into silicon and niobium into a high-grade steel alloy. The implantation depths were 100 nm for carbon and 30 nm for niobium.