Atomic Layer Deposition Process Modeling and Experimental Investigation for Sustainable Manufacturing of Nano Thin Films

This paper studies the adverse environmental impacts of atomic layer deposition (ALD) nanotechnology on manufacturing of Al₂O₃ nanoscale thin films. Numerical simulations with detailed ALD surface reaction mechanism developed based on density functional theory (DFT) and atomic-level calculations are performed to investigate the effects of four process parameters including process temperature, pulse time, purge time, and carrier gas flow rate on ALD film deposition rate, process emissions, and wastes. Full-cycle ALD simulations reveal that the depositions of nano thin films in ALD are in essence the chemisorption of the gaseous species and the conversion of surface species. Methane emissions are positively proportional to the film deposition process. The studies show that process temperature fundamentally affects the ALD chemical process by changing the energy states of the surface species. Pulse time is directly related to the precursor dosage. Purge time influences the ALD process by changing the gas-surface interaction time, and a higher carrier gas flow rate can alter the ALD flow field by accelerating the convective heat and mass transfer in ALD process.