LABORATORI NAZIONALI DI LEGNARO
Thin film materials technology is the foundation of all current modern technologies such as electronics, computers, data storages, displays, mobile devices and Internet network communications. It is used in many applications such as microelectronics, optics, hard and corrosion resistant coatings, micromechanics and RF superconductivity. Thin films form a uniquely versatile material base for the development of novel technologies within these industries. The properties of a thin film of a given material depend on the film's real structure. The real structure is defined as the link between a thin film's deposition parameters and its properties. To facilitate engineering the properties of a thin film by manipulating its real structure, thin-film formation is reviewed as a process starting with nucleation followed by coalescence and subsequent thickness growth, all stages of which can be influenced by deposition parameters. The focus in this lseminar is on metallic and dielectric films in the context of superconductivity.
Numerous techniques are available to grow high-quality thin films, such as chemical vapor deposition, thermal evaporation, atomic layer deposition, and physical vapor deposition sputtering. Recently, significant progress has been made in the development of energetic vacuum deposition techniques. The purpose of using energetic condensation is to improve film structure on low temperature substrates by adding energy to the film during condensation to compensate for the lack of thermally induced growth processes. Energetic condensation is characterized by a number of surface and sub-surface processes enabled by the energy of the incoming ions such as desorption of adsorbed molecules, enhanced mobility of surface atoms, and implantation of impinging ions under the surface. All these with the nature of the substrate and its crystallographic mismatch with the deposited film have an important influence on the nucleation and subsequent growth of the film.
In this context, the basic phenomena on the substrate are described and the mechanisms of nucleation and growth of thin films are reviewed.