High-dose ion implantation using a high-current plasma lens

A high-current plasma lens has been used to focus a large area energetic ion beam and thereby to increase the ion current density by a factor of up to 30, providing a convenient, simple and quick way of carrying out high-dose ion implantation. Here we review the characteristics and performance of the plasma lens, and describe demonstration experiments in which broad beams of carbon and cobalt ions (separately), formed from a vacuum arc ion source, were implanted into silicon test substrates. The carbon implantation was done at an ion energy of 30 keV and to a dose of 5×1017 cm−2, and the cobalt implantation was done at a mean Co ion energy of 50 keV and to a dose of 2×1017 cm−2. The carbon-implanted samples were annealed in an inert atmosphere to produce epitaxial β-SiC, and the cobalt-implanted samples were annealed to produce polycrystalline CoSi2. The recrystallization reactions were monitored using X-ray diffraction. The experiments demonstrate that high-current ion beams can be focused by a plasma lens in this way, providing a tool for compressing the ion beam current density by over an order of magnitude. The plasma lens offers a relatively simple ion beam tool for applications calling for high-implanted ion concentrations.