High-intensity oxygen cluster ion beam generation and its application to cluster ion-assisted deposition

Abstract

Oxide film formation using high-intensity oxygen cluster ion beams has been developed. This deposition process uses large cluster ions, which can transport thousands of atoms per ion with very low energy per constituent atom. As a result, the interactions between the cluster and substrate atoms occur in the near-surface region, and cluster ions can deposit their energy with a high density in a very localized surface region. Enhancement of the oxidation reactions is clearly demonstrated. High-quality tin-doped indiumoxide (ITO) films, which are widely used in electrical and optical devices, are formed. Very smooth, highly transparent (> 80%) and low-resistivity (< 4 × 10 −4 Ω cm, which are the lowest values for films grown at room temperature) films, were obtained by the use of a 7 keV oxygen cluster ion beam. The energetic oxygen clusters collapsed at the surface and reacted with the metal atoms, and about 10% of them were incorporated when the kinetic energy of the cluster ion was above 5 keV. Oxidation reaction can be enhanced by energetic cluster ion bombardment, which offers a new technique for ion-assisted thin-film formation.

Cluster–surface interaction: From soft landing to implantation

“…Soft landing of organometallic or organic compounds produced by cluster techniques are often used in surface chemistry, see for instance[220] as an example of softlanding experiments of vanadium-benzene clusters.Cluster ion beam processing in conjunction with other methods may provide the opportunity to realise otherwise difficult to obtain compositions and material phases or required structures and film parameters. Cluster ion beam-assisted deposition has been used, for example, for the growth of high-quality, thin and smooth films of ITO[221], Ta 2 O 5 , Nb 2 O 5[222] and TiO 2[223]. The formation of smooth thin films as components of complex glass/polymer/metal oxide heterojunction systems in the fabrication of light-emitting devices was also shown to be an advantage of cluster beam technique[224].…”