Atomic layer deposition (ALD) and molecular layer deposition (MLD) are important thin film deposition processes based on sequential, self-limiting surface reactions. ALD and MLD can deposit conformal and ultrathin inorganic and organic films with atomic/molecular layer control. ALD was recognized as the transformative technology when ALD was added to the semiconductor roadmap over ten years ago. ALD and MLD have the potential to make an even more significant impact if their throughput and cost can be improved using roll-to-roll (R2R) processes. For example, ALD and MLD could be used to fabricate high quality gas diffusion barrier on polymers for organic light emitting diodes and thin film photovoltaics. ALD could also be employed to coat the electrodes of Li ion batteries to improve their capacity stability and greatly extend their lifetime. Laboratory results have already confirmed the excellent performance of ALD barriers and coatings. Transitioning these laboratory results to the market requires a rapid and cost-effective method to perform ALD and MLD on polymer or foil webs.
This project will build an R2R ALD/MLD testbed with process control for web speeds of up to 30 m/min. To accomplish this challenging goal, computational fluid dynamics modeling will be performed to understand ALD/MLD and support the systematic design of novel gas source heads for ALD/MLD on both flat and porous substrates. The gas source heads will be integrated with a R2R web handling machine and this new apparatus will be optimized using studies of in situ monitoring of thickness versus processing parameters. Reduced order models will be studied and applied to achieve optimal performance. In addition, new methodologies will be developed for web handling such as the placement of the gas source head in the region of web wrap on a roller. The interdisciplinary team will also work with ALD NanoSolutions, a local startup company. ALD NanoSolutions is currently developing an R2R ALD testbed to coat flat polymer web substrates. The team will also collaborate with the National Renewable Energy Laboratory, Sandia Labs, Formosa Plastic and Kent Displays for potential scale-up manufacturing.
R2R ALD/MLD nano-manufacturing will facilitate the commercialization of ALD/MLD for a large number of applications and help to restore U.S. manufacturing competitiveness. This research will also educate and train undergraduate and graduate students to perform original research in scalable nano-manufacturing. A new section on ALD/MLD-enabled systems will be introduced into a first-year mechanical engineering projects course. These projects will develop designs that will be used in the K-12 outreach programs. R2R manufacturing teaching modules will be also introduced into existing undergraduate and graduate courses. The results of this research will also be widely disseminated at various scientific meetings and through a project web site.
