Atomic layer deposition (ALD) is a method to fabricate uniform and conformal thin films based on surface chemistry. Al 2 O 3 (alumina) is the most widely and thoroughly studied material in the field of oxide ALD. Most previous mechanistic studies on ALD of Al 2 O 3 have been focused on the surface reaction step of Al-containing precursor: for the popular trimethylaluminum, it is known that the surface becomes terminated with Al-CH 3 groups. However, reaction mechanisms for oxygen sources other than H 2 O has been largely unexplored. In this study, the surface reaction mechanisms for the CH 3 -terminated alumina surface with H 2 O, H 2 O 2 , and O 3 oxidants were investigated at molecular level. Density functional theory (DFT) calculations were used to obtain the energy change along reaction coordinates. It is confirmed that all three oxidants considered in this study would show facile oxidation of surface CH 3 into OH under ALD conditions. Still, the exact mechanisms and number of oxidant molecules required for a full reaction to generate hydroxyl-terminated surface vary. The molecular reactivity toward ALD of Al 2 O 3 at low deposition temperatures for the three oxidizing agents are expected to be H 2 O < H 2 O 2 < O 3 .
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Surfaces, Coatings and Films