A Water-free Low Temperature Process for Atomic Layer Deposition of Al_2O_3 Films

摘要

A new low temperature atomic layer deposition (LT-ALD) Al_2O_3 process using trimethylaluminum (TMA) and acetic acid (CH_3COOH) is studied both theoretically and experimentally. The atomistic mechanisms of the two deposition half-cycles on Al-CH_3~*, Al-OH~*, and Al(η~2-O_2CCH_3)~* are investigated using density functional theory (DFT). The experimental demonstrations are performed on Si substrates over the growth temperature range 75–400°C. Consistent with the DFT simulation, lower linear growth rate and shorter required oxidant purge times are observed at 90°C, when compared to LT-ALD Al_2O_3 using H2O as the oxidant. The chemical characteristics of the Al_2O_3 films grown with both CH_3COOH at 90°C and H_2O at 100°C are determined and compared using X-ray photoelectron spectroscopy (XPS).