Numerical simulation of molecular layer deposition for the formation of amorphous zeolitic imidazolate framework films

Amorphous zinc-imidazolate (aZnmIm) deposition on silicon substrates via atomic/molecular layer deposition (ALD/MLD) is an essential step for the recently introduced all-dry resist technology. This study presents a computational fluid dynamics (CFD) model for the 2-methylimidazolate (HmIm) half-MLD cycle and visualization of the transport phenomena inside the ALD/MLD reactor. The surface kinetics was extracted using the reactor-substrate simulation combined with experimental measurements. The model presented is thoroughly validated using experimental data. Steric hindrance from the bulky HmIm molecule significantly suppresses deposition, especially at low temperatures. The effects of substrate size and placement in the reactor on film uniformity are numerically examined and experimentally validated, and the decoupling of reactor-scale transport and substrate-scale deposition is verified. A distributor-based reactor optimization strategy is proposed, which, according to simulations, could reduce the non-uniformity from 14.7% to 8.0%. This study contributes to MLD process development and reactor design.