Atomic Layer Deposition and Microgravity Applications
Atomic Layer Deposition (ALD) is an innovative thin film growth technique, enabling ultra-thin layers of different materials to be applied onto complex 3D objects with excellent thickness control and conformity. ALD technology is one of the core drivers of modern electronics; from display screens, image sensors and MEMS to green energy and jewelry it powers everything we use today.
At ALD, thin films are created through sequential exposure of substrates with chemical vapors known as precursors. Each precursor exposure lasts only a short while before depositing several monolayers of material on the surface – this self-limiting effect known as ALD cycle provides atomic level control over coating thickness. Furthermore, ALD process can be used to create various materials, from oxides, nitrides, and sulfides to pure metals and organic polymers.
Conventional ALD processes separate precursor gases by time, necessitating evacuation and purge steps between each exposure. But new techniques like space-selective ALD (S-ALD) allow precursors to be separated spatially instead of time – eliminating evacuation and purge steps altogether, making the ALD process possible at ambient pressure and significantly lowering both operational and capital costs associated with traditional ALD technologies like CVD/PVD technologies.
Plasma-enhanced ALD (PEALD), another significant development in ALD, uses small amounts of energy from sources like tungsten filaments or noble gases such as nitrogen to activate the ALD reaction and greatly accelerate deposition rate and achieve higher purity coatings on inorganic-organic hybrid surfaces.
Spatial ALD with bottom-up area-selective ALD makes it possible to apply materials directly onto complex 3-D structures such as porous materials and shaped objects, or on their interior surfaces, opening up an array of applications including fabrication of micro and nanodevices for use in space, Earth observation, planetary science, and astrophysics.
ATLANT 3D Nanosystems has created a microscale AP-ALD reactor capable of performing ALD in space. When combined with advanced mechatronics, this reactor can pattern ALD compatible materials using microreactor selective area direct atomic processing (mSADALP). Our approach has proven that it meets stringent Space requirements while opening new opportunities for exploration of outer space.
For more information about ALD microgravity applications, please visit the ATLANT website. To watch a video showcasing ATLANT’s microgravity mSADALP capabilities, click here. Also performed is an R-Studio/R-Studio analysis from 2016-2021 conducted using data obtained from Scopus database.