Magnesium fluoride (MgF2) has been commonly utilized for optical coatings to increase the performance of optical components, such as anti-reflection coatings for lenses, and mirrors. MgF2 properties, such as low refractive index below 1.4, and relative stability against various chemicals are desired for many optical and barrier layers. However, its applicability has been limited because MgF2 has typically only been deposited with physical vapour deposition (PVD).
Atomic layer deposition (ALD) is a method to provide uniform and conformal coatings for 3D structures, even on inner surfaces of objects. This is not possible with conventional PVD methods. To facilitate demanding optical coatings, ALD MgF2 coatings were successfully developed using a commercially available ALD reactor, Picosun R-200 Advanced in a joint R&D project by Shincron and Picosun.
Available ALD processes for optical films also include Al2O3, SiO2, HfO2, and TiO2. All the established ALD coating processes enable new applications for optical and barrier layer coatings.