New ALD system can precisely coat complex-shaped optics
The Laser Zentrum Hannover (LZH) has developed a new Spatial ALD (atomic layer deposition) system for uniformly coating complex-shaped optics.
The innovative system achieves higher deposition rates than previously possible, and is of interest for applications in automotive lighting or the VR/AR sectors, among others.
ALD technology can produce ultra-thin, high-quality coatings, and has so far been used primarily to produce thin functional layers in the semiconductor industry. The new Spatial ALD system, which LZH developed in cooperation with Finnish company Beneq, now makes another high-demand industrial application economically viable.
The system can produce layer systems of uniform thickness much faster than before, for example on strongly curved and structured optics. Previously used methods, such as electron beam evaporation or ion beam sputtering, are severely limited in this respect.
This capability is of interest, for example, in the fields of automotive lighting or VR/AR, where three-dimensionally shaped lighting elements are essential. As the system is plasma-based, it can operate with low temperatures below 100 degrees – making it particularly suitable for coating temperature-sensitive polymer optics, which are often used for displays.
The ALD process is based on self-limiting chemical reactions between gaseous precursors and substrate surfaces. In systems commonly used at present, the process reactions are carried out one after the other, which necessitates a time-consuming gas exchange of the entire reaction chamber. For the new Spatial ALD system, the process cycles take place spatially separated. The system has four individual process chambers separated by pressure and nitrogen, in each of which an ALD reaction step is completed. The substrates then rotate into the next chamber. In this way, the scientists achieve deposition rates that were previously only possible with other coating processes. This makes the process particularly economical and at the same time enables high throughput in optical coating.
The LZH scientists presented their first research results with the new system at this year's Photonics West. They are also currently working in the ‘Integra’ project, funded by the Eureka Network’s ‘Eurostars’ programme, to coat optical diffraction gratings using the new system.
The LZH is also open to new challenges with the Spatial ALD system in the context of further industry and research collaborations.