Mechanisms of Surface and Microstructure Evolution in Deposited Films and Film Structures:

Mechanisms of Surface and Microstructure Evolution in Deposited Films and Film Structures:
Author: John Sanchez, Jr
Publisher: Cambridge University Press
Total Pages: 508
Release: 2014-06-05
Genre: Technology & Engineering
ISBN: 9781107412170

A wide variety of materials systems and deposition strategies have been developed to produce epitaxial and polycrystalline thin films. In particular, controlling the morphology and microstructure of metal films at the nanometer and/or micron scale has become crucial for applications such as giant magnetoresistive devices, contacts and diffusion barriers in integrated circuits and photovoltaics, and multilayer X-ray mirrors. This book, first published in 2001, focuses on the interactions between different mechanisms of microstructure evolution and film-growth conditions. Two sections of the volume, including a joint effort with Symposium R, Morphology and Dynamics of Crystal Surfaces in Molecular and Colloid Systems, highlight the fundamental mechanisms of epitaxial growth. Additional topics include: multilayers - stress in thin films; early stages of film growth - mechanical properties; texture in polycrystalline films; grain growth - barrier layers; and silicides and organic thin films - pulsed laser deposition.

Mechanisms for Intrinsic Stress Evolution During and After Polycrystalline Film Growth

Mechanisms for Intrinsic Stress Evolution During and After Polycrystalline Film Growth
Author: Hang Yu (Ph. D.)
Publisher:
Total Pages: 222
Release: 2013
Genre:
ISBN:

Growth of polycrystalline films involves poorly understood kinetic processes that occur far from equilibrium and lead to complex co-evolution of the surface, microstructure and intrinsic stress of the films. Here we present a comprehensive study consisting of in situ stress measurements, microstructure characterization, and analytical modeling for various polycrystalline systems. We find that in systems of high atomic mobility, the stress change after polycrystalline film growth can be attributed to a fast reversible surface process and a slow irreversible bulk process. The fast process is weakly dependent on temperature and is associated with changes in the shape of grain surfaces. The slow process is strongly dependent on temperature and is mostly associated with grain growth in the bulk of the film. We also discovered a turnaround phenomenon in which, under conditions of intermediate atomic mobility, the stress evolves from a tensile toward a compressive state, and then turns around to evolve toward a tensile state. This stress turnaround phenomenon is strongly dependent on the substrate temperature and deposition rate, and can be attributed to an increase of the grain size during film deposition. Grain growth during deposition not only leads to a tensile component of the intrinsic stress, but also changes the grain size dependence of the compressive component. The compressive component results from incorporation of excess adatoms in grain boundaries, and the magnitude of the compressive stress is controlled by a competition between adatom incorporation in 2D islands and incorporation at grain boundaries. We also investigated the effect of the angle of incidence of the flux of depositing atoms on stress and structure evolution during polycrystalline film growth. We find that as the angle of incidence increases, the coalescence thickness increases and the stress becomes less compressive or more tensile. We attribute these phenomena to the enhanced surface roughness, the shadowing effect, the steering effect and the presence of Ehrlich-Schwoebel barriers during oblique angle deposition. All these effects lead to suppression of the adatom-grain boundary incorporation process. Based on this thesis work, intrinsic stresses in polycrystalline films can be categorized into three types: Type I, the intermediate type and Type II. These behaviors are observed in systems of low, intermediate and high atomic mobility, respectively. Compressive stresses develop in Type II behavior and tensile stresses develop in Type I behavior. The transition of the stress behavior from Type I, to the intermediate type and to Type II is continuous and can be achieved by adjusting deposition conditions. Whether the post-coalescence stress is tensile, or compressive, or evolving from compressive to tensile depends on the homologous temperature, the deposition rate and the angle of the incidence of the flux of depositing atoms.

Science and Technology of Thin Films

Science and Technology of Thin Films
Author: F. C. Matacotta
Publisher: World Scientific
Total Pages: 369
Release: 1995
Genre: Science
ISBN: 9810221932

This book brings together detailed discussions by leading experts on the various innovative aspects of thin films growth, deposition and characterization techniques, and new thin film materials and devices. It addresses through the different viewpoints of the contributors, the major problem of thin films science - the relation between the energy of the condensing species and the resulting properties of the films. Some of the issues considered include energetic condensation, bombardment stabilization, pulsed electron beam ablation, orientation and self-organization of organic, ferroelectric and nanoparticle thin films. Several chapters focus on applications such as the recent developments in organic optoelectronics, large area electronic technology and superconducting thin film devices.