Manufacturing with Light 2: photochemical ALD to manufacture functional thin films

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The purpose of this project is to develop a novel photochemical atomic layer deposition (ALD) manufacturing technology to coat three - dimensional components and feedstock powders with ultrathin functional coatings. Conventional atomic layer deposition is already widely used in the displays and microelectronics industries. It is a thermo-chemical process where two precursor reagents are pulsed in cycles onto a heated work piece. The combination of the substrate temperature and the chemical reaction energy drive the process forward to deposit the thin film layer by layer. Because the process occurs on the surface, highly uniform and conformal layers can be deposited onto high-aspect ratio or porous materials with ultraprecise thickness control. The hypothesis for the proposed research is to use a photo-excitation process to activate one or both of the ALD chemical reagents so that they can react to deposit the thin film with a lower thermal input from a substrate heater. We will adapt the existing Round 1 ALD reactor at Liverpool to incorporate a larger scale chamber capable of containing: (1) an array of 3D components; and (2) reactor furniture for a fluidised bed powder treatment system. The modified system will be built to accommodate ultraviolet sources for the processing of 3D components or the treatment of powder beds. We also propose to use new UV source lamps to target the wavelength of the output from a range of commercially available UV lamp modules to photo-chemically decompose the precursors to form the film. The replacement chamber will also be manufactured to enable access for in-situ monitoring of the deposition process using an existing fibre-optic cable based Raman probe and a quartz crystal microbalance. These will provide feedback on the start of deposition as a function of illumination, substrate temperature, flow rates etc. If achieved, these objectives represent a significant advancement of existing ALD technology and would open up new applications where ultrathin functional materials can be exploited, such as display electronics, biomedical devices and photovoltaics amongst others.