Cluster ion beam process technology

Since an initial study of gas cluster ion beam (GCIB) had started in Ion Beam Engineering Experimental Laboratory, Kyoto University, more than 15 years has passed. Some of the results are already been applied for an industrial use. Unique characteristics of GCIB bombardment have been found to offer potential for various industrial applications that cannot be achieved by conventional ion beam processing. Impact of an accelerated cluster ion upon a target surface imparts very high-energy densities into the impact area and produces non-linear effects that are not observed in impacts of atomic ions. Among prospective applications are included shallow ion implantation, high-rate sputtering, surface cleaning and smoothing, and low-temperature thin film formation. Low-energy bombarding effects and sputtering effects produced by the cluster ion impact are particularly important. Cluster ion implantation has been applied to realize ultra-shallow junction formation. High-sputtering yields and lateral sputtering that cause surface smoothing cannot be achieved with monomer ion beams. The surface smoothing process to atomic levels becomes the first production use of GCIB. High-quality thin film formation using GCIB assisted deposition is also the characteristic that is explained mainly due to the very low energy and very high-density ion bombardment. (C) 2003 Elsevier Science B.V. All rights reserved.