Microstructural evolution during film growth

Abstract

Atomic-scale control and manipulation of the microstructure of polycrystalline thin films during kinetically limited low-temperature deposition, crucial for a broad range of industrial applications, has been a leading goal of materials science during the past decades. Here, we review the present understanding of film growth processes—nucleation, coalescence, competitive grain growth, and recrystallization—and their role in microstructural evolution as a function of deposition variables including temperature, the presence of reactive species, and the use of low-energy ion irradiation during growth.

Surfactant Aggregates at Rough Solid−Liquid Interfaces

“…This was accomplished using a Denton V-502A (Denton Vacuum, Moorestown, NJ) electron beam evaporator at pressures below 10 -6 mbar and an evaporation rate of 0.3 nm/s. The samples were either used with the rough surface obtained after this step 50 or treated further to render the surfaces as smooth as possible. This was achieved by annealing with a hydrogen flame, using a National 3H stainless steel hydrogen torch with an OX-3 tip (Premier Industries, Blaine, MN).…”

An introduction to thin film processing using high-power impulse magnetron sputtering

“…10(a) for CrN films]. 31,91,119 Growth of films using HiPIMS is characterized by high ionic fluxes to the substrate (up to several hundreds of milliamperes per square centimeter) of relatively low energies (several tens of electronvolts), as was discussed in Section II B. These growth conditions trigger and/or enhance surface diffusion leading to film densification 31,123 as shown in Fig.…”

“…39,90 Numerous studies have shown that during the film growth, the plasmafilm interface is affected by the energy of the bombarding ions, their flux, their nature, and their angle of incidence. 91,92 These parameters determine the efficiency of the momentum transfer to the film atoms 93 and have been shown to have implications on the film microstructure 91 as well as on mechanical, optical, and electrical properties. 90,94,95 In HiPIMS, high pulsed ion fluxes are made available at the substrate.…”

“…113,114 C. Control of film microstructure and interface engineering Polycrystalline films grown by PVD techniques exhibit a variety of microstructures with respect to the size, the morphology, and the relative orientation of the crystallites. 91,119 These features have, for instance, implications for the mechanical strength 120 and the electrical conductivity 94,95,121 of the film. The microstructure is determined primarily by surface and bulk diffusion processes, 91,119 which are controlled by the deposition temperature, the bombardment by energetic species, and the incorporation of impurities that act as inhibitors for the crystal and grain growth.…”

“…91,119 These features have, for instance, implications for the mechanical strength 120 and the electrical conductivity 94,95,121 of the film. The microstructure is determined primarily by surface and bulk diffusion processes, 91,119 which are controlled by the deposition temperature, the bombardment by energetic species, and the incorporation of impurities that act as inhibitors for the crystal and grain growth. 91,119,122 Deposition at relatively low temperatures (typically lower than 0.4T m , where T m is the melting temperature of the deposited material) using state-of-the-art sputtering techniques allows only for surface diffusion to be activated leading to the formation of films with a columnar microstructure and intercolumnar porosity [see Fig.…”