Recent advances in surface processing with metal plasma and ion beams

Surface processing by metal plasma and ion beams can be effected using the dense metal plasma formed in a vacuum are discharge embodied either in a "metal plasma immersion" configuration or as a vacuum are ion source, as well as by many other well-established methods. In the former case the substrate is immersed in the plasma and repetitively pulse-biased to accelerate the ions across the sheath and allow controlled ion energy implantation + deposition, and in the latter case a high energy metal ion beam is formed and ion implantation is done in a more-or-less conventional way. These methods have been used widely; here we limit consideration to work carried out at the Lawrence Berkeley National Laboratory. A number of advances have been made both in the plasma technology and in the surface modification procedures that enhance the effectiveness and versatility of the methods. Recent improvements in plasma technology include dual-source plasma mixing, ion charge state enhancement, and some scale-up of the hardware. We have made and explored some novel kinds of surface films and modified layers, including for example doped diamond-like carbon (DLC), novel multilayers, alumina and more complex ceramic materials such as mullite (3Al(2)O(3). 2SiO(2)), high temperature superconducting films, and others. Recent research has included investigations of these and other surface materials for many different basic and applied applications, such as for high temperature tolerant protective coatings, biomedical compatibility, surface resistivity tailoring of ceramics, novel catalytic surfaces, corrosion resistance of battery electrodes, and more. Here we briefly review the fundamentals of the techniques, and describe some of the applications to which the methods have been put at the Lawrence Berkeley National Laboratory. (C) 1999 Elsevier Science S.A. All rights reserved.