Study of rotary atomic layer deposition for optical applications

authored by: Leif Kochanneck, Andreas Tewes, Gerd Albert Hoffmann, Kalle Niiranen, John Rönn, Hector Velasco, Sami Sneck, Andreas Wienke, Detlev Ristau
Abstract: Atomic layer deposition (ALD) has been proven as an excellent method for coating high quality optical films due to its outstanding film quality and precise process control. Unfortunately, batch ALD requires time-consuming purge steps, which lead to low deposition rates and highly time-intensive processes for complex multilayer coatings. Recently, rotary ALD came in focus for optical applications. In this novel process concept, each process step takes place in a separate part of the reactor divided by pressure and nitrogen curtains. The substrates to-be-coated are rotated through these zones. During each rotation, an ALD cycle is completed, thus the deposition rate is mainly dependent on the rotation speed. In this study, the performance of a novel rotary ALD coating tool for optical applications is investigated and characterized with SiO2 and Ta2O5 layers. Low absorption levels of 3.1 ppm for 200 nm thick single layer of Ta2O5 and 6.0 ppm for 1032 nm thick single layer of SiO2 are demonstrated at 1064 nm, respectively, with growth rates up to 0.18 nm/s on fused silica substrates. Furthermore, excellent uniformity is also demonstrated with non-uniformity values reaching as low as 1.55 % and 2.71% for Ta2O5 and SiO2, respectively, over 120 mm on silicon wafers. Seven substrates up to a diameter of 200 mm can be coated in each run. Further investigations on uniformity improvements and multilayer coatings are currently ongoing.
Organisation(s): PhoenixD: Photonics, Optics, and Engineering - Innovation Across Disciplines
Institute of Quantum Optics
External Organisation(s): Laser Zentrum Hannover e.V. (LZH)
Beneq Oy
Type: Conference contribution
Publication date: 05.03.2022
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Condensed Matter Physics, Computer Science Applications, Applied Mathematics, Electrical and Electronic Engineering
Electronic version(s): https://doi.org/10.1117/12.2612173 (Access: Closed)