Precision Coating

Flash lamp annealing (FLA) device integrated into a vertical in-line vacuum coating system for demonstration of an industrial scale of 1200 × 600 mm2 surface treatment as part of the publicly funded project INNOFLASH..

As part of the publicly funded technology project INNOFLASH by the Saxon State Ministry for Economic Affairs, Labor and Transport, the technology of flash lamp annealing (FLA) in vacuum has been successfully scaled. The aim was to provide an energy-efficient method for effective short-term annealing of large substrates using xenon flash lamps, which heat treats only the very surface region without thermally stressing the entire substrate. This was achieved through the use of 750 mm flash lamps that span the entire substrate width, and by providing sufficient energy densities, for example for the recrystallization of ITO thin films with proven industrial relevant lamp lifetimes.

The key was the development of an innovative power supply concept together with our project partner Rovak GmbH, which ensures the following parameters:

• High energy density > 25 J/cm²
• Adjustable pulse duration (between 1 ms and 10 ms)
• High repetition (flash) frequency (up to 2 Hz)
• Long-term stable and reproducible FLA process (1 million flashes)

This new power supply concept reliably handles the high currents and voltages that occur in the millisecond range in the FLA process and enables precise and effective process control, as required for the use of FLA in industrial large-scale in-line applications, e. g. for:

• Activation of dopants for transparent conductive oxides such as ITO: The sheet resistance of unsintered ITO films with a thickness of 150 nm on float glass was reduced by FLA from 600 µΩcm to 215 µΩcm while increasing the transmission by 10% to 87% (TVIS according to DIN EN410)
• Crystallization of thin films, e. g. for thermochromy (vanadium oxide) or crystalline optical or photocatalytic coatings (TiO₂)
• Controlled in-vacuo de-wetting of thin metal island layers (e. g. Cu and Ag) for biozidic applications

Compared to conventional annealing, FLA offers higher energy and process efficiency, resulting in lower investment and operating costs for surface technologies.

FLA is also suitable for treating sensitive or innovative substrate materials, such as temperature-sensitive polymers or ultra-thin flexible glasses with their special heat conduction properties, offering a high potential for a variety of applications in the future.