Beneq (Finland)

We report the development of an atomic layer deposition (ALD) process for depositing titanium dioxide (TiO 2 ) nanofilms onto porous activated carbon (AC) electrodes to enhance the electrochemical performance of supercapacitors. This study investigates previously unexplored aspects of the ALD process, including the influence of precursor pulse duration and film thickness on the deposition behavior within complex porous AC structures. The deposited TiO 2 nanofilms were amorphous and exhibited excellent uniformity and conformality across the AC surface. Electrochemical measurements revealed a combination of surface redox and intercalation-type pseudocapacitance, with surface redox reactions identified as the dominant energy storage mechanism. An optimal balance between accessible surface area and film thickness was achieved at 60 ALD cycles, corresponding to a TiO 2 film thickness of approximately 2.3 nm. Under these conditions, the specific capacitance of TiO 2 -coated supercapacitors exceeded that of bare AC electrodes, owing to the additional pseudocapacitance contributed by the TiO 2 layer. These findings demonstrate an effective strategy for utilizing ALD to engineer advanced electrode materials for high-performance supercapacitors. • Interfacial decoration of TiO 2 nanofilms on AC supercapacitors via ALD technique. • Highly uniform and conformal TiO 2 nanofilms observed in SEM/cross-sectional TEM. • The TiO 2 /AC demonstrate higher capacitance during extensive charge-discharge cycles. • New insights on next generation supercapacitors based TiO 2 ALD-coated AC electrodes.

In this work, we present a new-generation atomic layer deposition (ALD) technology that revolutionizes the production of conformal optical coatings: the spatial ALD. In spatial ALD, the substrate is rotated across successive process zones to achieve ultra-fast, high-precision and conformal thin film deposition. We present our latest results obtained with our novel C2R spatial ALD system, including the fabrication of SiO2, Ta2O5, Al2O3 and TiO2 with deposition rates reaching > 1 µm/h. We also show that these materials exhibit low surface roughness (<1 Å RMS), low optical loss (<10 ppm @ 1064 nm) and excellent uniformity (< 2% over 200 mm)

ALD coatings have been developed to protect process equipment against aggressive process conditions, specifically fluoride plasma. Here alumina and yttria based ALD coatings were deposited in a large-batch ALD reactor on silicon samples and mock-up showerheads. High conformality in 1:20 aspect ratio features was demonstrated. Plasma etch testing of the film revealed high resistance against the etch process for all the films in the Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> -Y <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> system. Y <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> mixing into the Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> film was shown to rapidly increase the etch resistance of the film with diminishing effect as pure yttria was approached. Etch damage on the film was uniform showing no preference on grain boundaries or other features.

We present a new-generation atomic layer deposition (ALD) technology that revolutionizes the production of conformal optical coatings: the spatial ALD. In spatial ALD, the substrate is rotated across successive process zones to achieve ultra-fast and high-precision thin film deposition. We present our latest results obtained with our novel C2R spatial ALD system, including the fabrication of SiO2, Ta2O5 and Al2O3 with deposition rates reaching > 1 µm/h. We also show that these materials exhibit low surface roughness (<1 Å RMS), low optical loss (<10 ppm @ 1064 nm), excellent uniformity (< 2% over 200 mm) and high damage threshold (up to 40 J/cm2).

Complex 3D-shaped optics are difficult to coat with conventional technologies. In this research, large top-open optical glass cubes with a 100mm side length were functionalized to simulate large dome-shaped optics. Antireflection coatings for the visible range (420-670nm) and for a single wavelength (550nm) were applied by atomic layer deposition simultaneously on two and six demonstrators, respectively. Reflectance measurements on both the inner and outer glass surfaces confirm a conformal AR coating with a residual reflectance significantly below 0.3% for visible wavelengths and 0.2% for single wavelengths on nearly the entire surface of the cubes.

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.

Optical Interference Coatingss deposited by thermal Atomic Layer Deposition (ALD) in large batches is presented. The use of ALD enables the ability to coat all surfaces of optical components conformally and with atomic layer precision. © 2019 The Author(s)

Atomic layer deposition (ALD) has been widely used in microelectromechanical systems (MEMS) due to its unique advantages, e.g. precise film thickness control, high uniformity and superb conformality. The understanding of ALD film's mechanical properties is important for MEMS device design and fabrication. In this work, the studied thin films (Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laminates) were deposited by thermal ALD (THALD) and plasma-enhanced ALD (PEALD). The film growth behavior was determined by ellipsometry, and the residual stress was analyzed by wafer curvature measurements. We extracted a low residual stress near 100 MPa for Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laminates. A clear correlation was found between the film's process conditions (parameters and configurations) and residual stress.