C-311 Thin Film Nucleation, Growth, and Microstructure Evolution
This tutorial is intended for scientists, engineers, technicians, and others involved with the vapor deposition of thin films by sputtering, evaporation, MBE, CVD, etc., and who need to obtain a better understanding of the effects of operating parameters on the properties of metal, semiconductor, and dielectric films and alloys. The tutorial is concentrated on the development of a detailed atomic-scale understanding of the primary experimental variables and surface reaction paths controlling nucleation/growth kinetics and microstructural evolution during vapor-phase deposition of thin films. The goal is to develop an appreciation of the advantages and disadvantages of competing growth techniques and to learn how to design better and more efficient film growth processes to achieve required properties. Thin films are pervasive in many advanced fields of modern technology including microelectronics, optics, magnetics, hard and corrosion-resistant coatings, micromechanics, etc. Progress in each of these areas depends upon the ability to selectively and controllably deposit films (thicknesses ranging from tens of Ångstroms to many micrometers) with specified physical properties. This, in turn, requires control—often at the atomic level—of film microstructure and microchemistry.Topical Outline:
- The role of the substrate in mediating growth kinetics
- The nucleation process
- Film growth modes
- The development and control of film stress (strain engineering)
- Nucleation and growth of strain-mediated self-organized structures
- Polycrystalline film growth, texture, and microstructure evolution
- Structure-zone models of film microstructure
- The role of low-energy ion/surface interactions during film growth
- The relationship between film growth parameters and film properties
Chapter 1. The substrate: an introduction to surface structure/processes
- surface energies: measurements and role in film growth
- surface structure: examples of reconstruction and relaxation
- terrace-step-kink structure: examples (STM)
- surface diffusion
- step-edge barrier and 2D kinetic roughening
- corner barrier and 1D kinetic roughening.
Chapter 2. Nucleation
- the nanoscience of nuclei and small clusters: reduced cohesive strength, depressed melting point, increased 2D vapor pressures
- thermodynamics of nucleation (a simple stability problem): examples
- capillarity-based atomic-scale models: examples
- wetting angle: examples(TEM, STM)
- graphene/fcc(111) moiré superstructure templates (STM, LEED)
- kinetics of nucleation: examples (STM)
- coalescence and coarsening: examples (TEM, STM videos)
- early stages of film growth (experiment and simulation): examples
- anisotropic edge diffusion
- strain effects.
Chapter 3. 2D step flow and layer-by-layer epitaxial growth
- introduction: Si on Si(001), a case study (STM, theory)
- 2D step flow
- definition and requirements
- possible to achieve?
- role of buffer layers: examples
- experimental observations: He, x-ray, and RHEED scattering
- layer-by-layer growth
- definition and requirements
- possible to achieve?
- experimental observations: He, x-ray, and RHEED scattering.
Chapter 4. 2D multilayer growth
- experimental observations: STM vs. RHEED oscillations
- simulations vs. experimental observations: examples
- low-temperature epitaxy: fundamental limits
- critical epitaxial temperature Tepi vs. critical thickness tepi
- techniques for increasing tepi
- surfactants: examples (STM and RHEED oscillations)
- hyperthermal beams: examples (XTEM).
Chapter 5. Heteroepitaxy and the role of misfit strain
- elastic strain energy
- edge, screw, and mixed dislocations: TEM, XTEM, & LEEM videos
- relaxation mechanisms: elastic energy vs. misfit dislocations and surface energy
- misfit dislocations, critical thickness, strategies to decrease dislocation density: examples
- surface roughening, islanding, S-K growth: examples
- quantum dot engineering: examples (STM, XTEM)
- quantum wires (STM)
- 2D layers: silicene4x4/Ag(111), silicene/ZrB2(0001), MoS2/Gr (STM, RHEED).
Chapter 6. 3-D polycrystalline growth and nanostructure evolution
- nucleation: examples (TEM, AFM, STM)
- coalescence: examples (TEM and STM videos)
- complete vs. incomplete: examples (STM)
- coarsening: examples (TEM and STM videos)
- grain boundaries in 2D materials: example Gr/Cu (STM and TEM)
- grain boundary energies
- grain growth: examples (TEM)
- thick films
- structure-zone models: experiment vs. computer simulations
- oblique deposition and atomic shadowing.
Chapter 7. Film stress and texture evolution
- thermal stress: examples
- stress measurement: examples
- tensile stress mechanisms: examples (TEM, XTEM)
- ion-induced stress: examples
- compressive stress mechanisms: examples (XTEM)
- stress in superlattices and multiplayer systems
- texture evolution: examples (AFM, XTEM, simulations).
is the D.B. Willett Professor of Materials Science and Physics, the Tage Erlander Professor of Materials Physics at Linkoping University, a Chaired Professor at the National Taiwan University of Science and Techology, and Past Director of the Frederick Seitz Materials Research Laboratory at the University of Illinois. The focus of his research has been the development of an atomic-level understanding of adatom/surface interactions during vapor-phase film growth in order to controllably manipulate microchemistry, microstructure, and physical properties. His work has involved film growth by all forms of sputter deposition (MBE, CVD, MOCVD, and ALE). He was President of the American Vacuum Society in 1989, a consultant for several research and development laboratories, and a visiting professor at several universities. Recent awards include receipt of the Aristotle Award from SRC (1998), the Adler Award from the American Physical Society (1998), Fellow of the American Vacuum Society (1993) and the American Physical Society (1998), the Turnbull Prize from the Materials Research Society (1999), Fellow of the Materials Research Society (2013), and the Mentor Award from SVC (2015). He was elected to the US National Academy of Engineering in 2003 and is the Editor-in-Chief of Thin Solid Films.
This course is currently available via:
On Location Education Program