Theoretical study on tin oxide surface chemistry mechanism and thermodynamic properties for atomic layer deposition equipment optimization

In order to obtain the reaction mechanism and thermodynamic parameters on tin oxide surface chemistry, which provide theoretical data for atomic layer deposition equipment optimization. The reaction mechanism of preparation of SnO 2 pathway for TDMASn and H 2 O half reaction by atomic layer deposition (ALD) was studied by Density Function Theory. The study employed the average local ion energy (ALIE) and electrostatic potential (ESP) to predict potential reaction sites. These reaction sites were identified by investigating the ALIE extremes and the distribution of ESP intervals between the reactants. The results revealed that the primary reaction sites resided between the nitrogen (N) atoms within three distinct dimethylamino moieties and the outer region of tin (Sn) atoms. Transition state calculations were subsequently performed to ascertain the activation energies of the reaction steps, which resulted in TS1 (11.75 kcal mol −1 ), TS2 (7.16 kcal mol −1 ), TS3 (6.49 kcal mol −1 ), and TS4 (5.76 kcal mol −1 ). The interaction region indicator analysis was employed to verify the reaction mechanism, and the breakage and reformation of chemical bonds during the reaction were analyzed. The reaction rate constant (k) was calculated by the transition state theory. The Wigner tunneling factor also was used for correction to determine the reaction rate constants at both the standard temperature (298.15 K) and the reaction temperature (413.15 K). Meanwhile, the thermodynamic parameters of each reactant and product were calculated. These parameters can provide theoretical data to computational fluid dynamics model for the design and optimization of equipment for the preparation of SnO 2 thin film using ALD.