Thin Films and Coatings Research Briefs
Research in the Materials Science and Engineering Center at Sandia National Laboratories includes the study of a variety of films, coatings, and related characterization techniques. We provide research and development support for other groups within Sandia, the Department of Energy, other government agencies, and private-sector companies. Areas of special emphasis and expertise within the program include:
- Sol-gel glass and ceramic films,
- Multilayer sputtered films,
- Porous silicon processing,
- Corrosion-resistant coatings,
- Thin-film and interface characterization,
- Numerical simulations of coatings,
- Photochromic films, and
- Small-angle x-ray characterization.
We have state-of-the-art facilities for studying fundamental processes in coating research. We develop new processing tools, diagnostics, and techniques grounded in fundamental concepts for the technology. We also develop prototype articles for evaluation by customers.
Sol-Gel Derived Glass and Ceramic Films: As part of our chemically prepared ceramics program, we investigate the fundamental chemistry and physics of ceramic film formation by spin, spray, and dip coating, and several self-assembly strategies including micropen, selective dewetting, and ink-jet patterning. Our capabilities include the design and synthesis of novel chemical precursors that provide additional control of film composition, morphology, and processing options.
Nanostructured ceramic film with ordered porosity made by self-assembly. Electron diffraction pattern (inset) indicates long-range order.electrochemical-based options to engineer surface properties. Unlike most other physical-deposition methods, sputtering can be used to deposit, simultaneously or sequentially, widely disparate materials such as metals and ceramics. Sandia maintains research and production sputtering units that can optimize films through independent control of target composition, substrate temperature, chamber pressure, deposition rates, process gas composition, process gas flow rates, and substrate bias. Thin films with excellent thickness control (>98%) and compositional uniformity can be obtained over large substrate areas (up to 8" diameter) using a 3"-diameter target. A sophisticated computer modeling and deposition program offers precise thickness control over large areas by moving (scanning) the substrate with respect to the sputter target during deposition. This program allows researchers to accurately model thickness profiles on figured substrates before deposition and, then, implement the optimum scanning algorithm. Figured substrates, such as optics, with excellent uniformity or optical interference coatings with prescribed thickness gradients can be made.
Thin-Film and Interface Characterization: To develop a fundamental understanding of film formation, interfacial chemistry, and physics, and its development in real time, Sandia has constructed several ultra-high vacuum analysis systems with appropriate surface and interface probes coupled to reaction chambers where either vapor-phase processing or liquid-phase electrochemical processing may be carried out.
Major Resources
- Personnel: Approximately 25 individuals contribute to these areas of research, including 10 Ph.D.-level staff members.
- Two Unifilm multi-source sputtering systems capable of thin film or multilayer depositions with excellent thickness and compositional uniformity, including a library of approximately 100 elemental and alloy-sputter targets.
- RF, DC, and pulsed-DC magnetron sputtering capabilities are available as well as reactive atmosphere sputtering with up to four process gases. A load lock increases throughput and minimizes chamber contamination.
- Stress measurement systems for performing in situ, thin-film stress measurements in the temperature range from ambient to 900ºC.
- Scanning electron microscope, atomic force microscope, and scanning tunneling microscope for characterizing film topography.
- Spin and dip-coating apparatus with unique imaging ellipsometer diagnostics for sol-gel coating.
- X-ray reflectometer and small-angle scattering instruments for probing films on the scale of a few nanometers to over a micrometer.
- Contact-angle measurement and adhesion stud pull tester to measure substrate cleanliness prior to deposition and adhesion of films after deposition.
Selected Accomplishments
- "Ambient pressure" aerogel films with low dielectric constant and high thermal insulation values have been synthesized, eliminating the need for critical-point drying.
- We have developed uncooled IR detector arrays integrating different film deposition techniques that allow high-volume manufacturability, while retaining state-of-the-art sensitivity.
- We achieved a world-best critical current density of 3 MA/cm2 at 77 K for crystallographically aligned, sol-gel derived YBa2Cu3O7-x superconductor thick films.
- We deposited highly reflective Mo/Si multilayer coatings for use at 13 nm for extreme ultraviolet (EUV) optics.
- We developed techniques to grow mixed metal-oxide thin films for catalytic processes, battery components, barrier layers, dielectrics, and ferroelectric memory elements.
Contacts: William Hammetter, (505) 272-7603, wfhamme@sandia.gov
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