Details

Autor(en) / Beteiligte

• Fang, Guo-Yong
• Xu, Li-Na
• Cao, Yan-Qiang
• Wang, Lai-Guo
• Wu, Di
• Li, Ai-Dong

Titel

Self-catalysis by aminosilanes and strong surface oxidation by O2 plasma in plasma-enhanced atomic layer deposition of high-quality SiO2Electronic supplementary information (ESI) available. See DOI: 10.1039/c4cc08004a

Erscheinungsjahr

2014-12

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Plasma-enhanced atomic layer deposition (PE-ALD) has been applied to prepare high-quality ultrathin films for microelectronics, catalysis, and energy applications. The possible pathways for SiO 2 PE-ALD using aminosilanes and O 2 plasma have been investigated by density functional theory calculations. The silane half-reaction between SiH 4 and surface -OH is very difficult and requires a high activation free energy of 57.8 kcal mol −1 . The introduction of an aminosilane, such as BDMAS, can reduce the activation free energy to 11.0 kcal mol −1 and the aminosilane plays the role of a self-catalyst in Si-O formation through the relevant half-reaction. Among the various species generated in O 2 plasma, 3 O 2 is inactive towards surface silane groups, similar to ordinary oxygen gas. The other three species, 1 O 2 , 1 O, and 3 O, can strongly oxidize surface silane groups through one-step or stepwise pathways. In the 3 O pathway, the triplet must be converted into the singlet and follow the 1 O pathway. Meanwhile, both 1 O and 3 O can decay to 1 O 2 and enter into the relevant oxidation pathway. The concept of self-catalysis of aminosilanes may be invoked to design and prepare more effective Si precursors for SiO 2 ALD. At the same time, the mechanism of strong surface oxidation by O 2 plasma may be exploited in the PE-ALD preparation of other oxides, such as Al 2 O 3 , HfO 2 , ZrO 2 , and TiO 2 . In SiO 2 PE-ALD, aminosilanes can self-catalyze Si-O formation and 1 O 2 , 1 O, and 3 O can strongly oxidize surface -SiH to -SiOH.