Abstract:
Atomic layer deposition (ALD) technology can deposit thin films on porous substrates with sub-nanometer precision, thereby adjusting the pore size and interface properties. Such ALD processes are affected by the diffusion and reaction of precursors, which causes difficulties in studying the reaction kinetics. In this paper, models were established for the depositions on the outer surface and inside the pores of the γ-Al
2O
3 substrate where ZnO films were formed via ALD. A sensitivity analysis was carried out for the two models through numerical simulation, which led to the formulas of surface coverage of the deposits. The results show that during the deposition on the outer surface of the substrate, with the increase of adsorption rate constant
ka, the conversion rate constant
k1 of adsorbed diethyl zinc to monoethyl zinc, the hydroxyl concentration
COH, and the decrease of the desorption rate constant
kd, the film deposition accelerates. For the deposition inside the pores, higher
COH and lower diffusion coefficient
DS result in deposit formation in a shallow position. The analytical formulas can accurately predict the deposit coverage and its distribution on the outer surface and inside the pores of porous substrates.