Ion beam assisted thin film deposition

Abstract

Ion beam technologies have made tremendous gains in the commercial sector over the past two decades. The ion implantation of semiconductors rapidly became an accepted technology in the 1970s because of its ability to produce superior electronic devices or devices unobtainable by any other process. Ion beam modification of non-semiconductor materials for enhancing surface sensitive properties has been actively pursued in the international R&D community since the mid 1970s and continues to find selected industrial applications. This review briefly describes the status of ion implantation, ion beam mixing, and ion cluster beam deposition technologies and the directions in which they are currently being pursued. The hybrid use of ion beams in conjunction with physical vapor deposition, commonly termed ion beam assisted deposition (IBAD), combines many of the attributes of these ion beam treatments and conventional coating technologies. These include high density, superior adhesion, and the ability to produce arbitrarily thick coatings. Perhaps the most important feature of the IBAD technology is the frequently demonstrated ability to control many coatings properties such as morphology, adhesion, stress, as well as stoichiometry. This control is achieved by suitable variation of the relative arrival rates of energetic ions to that of the neutral species, as well as by control of substrate temperature. Many of these energetic ion effects on thin film formation are described and recent examples of research in the areas of: metastable compound formation, optical and electronic coatings, and tribological and corrosion-resistant coatings are presented. The review concludes with a description of pertinent equipment and an assessment of required future research and commercialization possibilities.