Jörg Neidhardt¹, Thomas Preußner¹, Marcel Neubert^2
1Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technologies FEP, Dresden, Germany
²ROVAK GmbH, Grumbach, Germany
Even though flash lamp annealing is not a new technology, commercially viable applications within the realm of coatings, thins films and surface engineering are still largely unexplored. Instead, static annealing procedures and/or deposition at elevated temperatures are frequently employed to adjust materials and/or surface properties for given applications. However, the applicable temperatures are often limited by substrate materials as well as unwanted side effects, such as diffusion, and/or economic considerations. Therefore, rapid (<50 ms) thermal annealing processes are an alternative technology enabling thermal treatment of functional layers and coatings. The limited penetration depth of the imposed heat can even allow the thermal treatment on temperature sensitive substrates. By superimposing periodic flashes and moving the substrate perpendicular to the lamp axis, large areas can be continuously and homogeneously annealed. Recent developments transferred this technology from lab-scale to a pilot scale level and even beyond providing a reproducible and effective large area treatment in air, controlled atmosphere or even in-line with vacuum processes. In comparison to conventional furnace processing, a superior energy efficiency is demonstrated at a comparatively small machine footprint at high throughput.
This talk introduces the principles of flash lamp annealing as well as the available equipment options for (large area) thin film and surface treatment for up to pilot-level. These will be related to selected applications and use cases explored at Fraunhofer FEP over the last decade. Examples are crystallization of large area TCO coatings in combination with inline FLA on rigid and ultra-thin bendable glass, treatment of Ag-based lowE multilayer stacks, formation of antimicrobial as well as plasmonic nanoparticles, surface activation of TiO_x thin films as well as toughening of plain glass surfaces. Furthermore, the FLA process itself is in the focus of research and commercial validation. Therefore, topics like long-term stability, scalability and energy efficiency will also be addressed.