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

A high-current plasma lens has been used to focus a large area energetic io n 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 th e plasma lens, and describe demonstration experiments in which broad beams of carbon and cobalt ions (separately), formed from a vacuum are 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 x 10(17) cm(-2), and the cobalt implantation was done at a mean Co ion energy of 50 keV and to a do se of 2 x 10(17) cm(-2). The carbon-implanted samples were annealed in an i nert atmosphere to produce epitaxial beta-SiC, and the cobalt-implanted sam ples were annealed to produce polycrystalline CoSi2. The recrystallization reactions were monitored using X-ray diffraction. The experiments demonstra te 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 o rder of magnitude. The plasma lens offers a relatively simple ion beam tool for applications calling for high-implanted ion concentrations. (C) 2000 E lsevier Science S.A. All rights reserved.