Kinetic study on initial surface reaction of titanium dioxide growth using tetrakis(dimethylamino)titanium and water in atomic layer deposition process: Density functional theory calculation

A theoretical study on the surface reaction of tetrakis(dimethylamino)titanium on titanium oxide

“…Promjun et al 37 simulated the reaction of TDMAT during the ALD process using (OH) 2 –Si 9 H 12 and (OH) 4 –Si 15 H 16 cluster models. Table 1 compares the results from our slab model and their cluster models.…”

“…A few other papers have simulated the surface reaction of a TDMAT molecule using cluster models. 26,37,40 However, we could not directly compare our calculation results with theirs due to the limited information about the cluster model and the interatomic distances during the reaction.…”

“…26 The reactions were favorable with low activation energies, suggesting that the process is feasible at low temperatures. However, two NMe 2 ligands remained after the chemisorption of TDMAT using the (OH) 2 –Si 9 H 12 model because it has only two hydroxyl active sites, 26,31,37 which does not fully explain the QCM analysis that only one ligand remained at 120 °C. Even in the case of (OH) 4 –Si 15 O 10 H 16 clusters, 26 the state with two NMe 2 ligands remaining was claimed to be the most stable.…”

“…When a cluster model is used as a substrate for an ALD process, it neglects the cooperative effect of surface groups. 41 In addition, the chemical nature of the hydroxyl group on SiO 2 or Si is also different from that on TiO 2 , 42,43 and the studies using silicon or silicon oxide cluster models 26,37 would represent the initial stage of ALD growth on silicon or silicon oxide instead of continuous TiO 2 growth. Therefore, the TiO 2 slab model is preferred to accurately simulate the ALD reaction.…”

“…The reaction mechanism of an ALD precursor can also be elucidated by DFT calculation. [32][33][34][35][36][37][38][39] However, the DFT study of the chemisorption of an alkylamide-type titanium precursor is still limited. Recently, the reaction mechanism of TDMAT on silicon oxide was studied using Si-based clusters as substrate models, such as (OH) 2 -Si 9 H 12 37,40 or (OH) 4 -Si 15 O 10 H 16 .…”