Theoretical Understanding of the Reaction Mechanism of SiO2 Atomic Layer Deposition

Atomic layer deposition (ALD) is a powerful nanofabrication technique for the preparation of uniform, conformal, and ultrathin films and allows accurate control of the composition and thickness of thin films at the atomic level. To date, ALD has been used for the growth of various materials, including oxides, nitrides, sulfides, metals, elements, compound semiconductors, and organic and organic–inorganic hybrid materials. As one of the most important inorganic materials, silicon dioxide (SiO2) has been used in the fields of microelectronics, catalysis, and energy storage and conversion. Various SiO2 ALD methods have been developed, which have expanded the research and applications of ALD chemistry and technology. Recent advances concerning the reaction mechanisms of SiO2 ALD have further deepened our understanding of the surface chemistry and related catalysis in the ALD of SiO2 and other oxides. Thin films of SiO2 can be obtained by means of thermal ALD and energy-enhanced ALD. Thermal ALD of SiO2 includes H2O-based ALD without a catalyst, room-temperature ALD (RT-ALD) catalyzed by a Lewis base, and rapid ALD (RALD) catalyzed by a Lewis acid. Energy-enhanced ALD of SiO2 encompasses plasma-enhanced ALD and O3-based ALD using aminosilane. In this review, we highlight the significance and advantages of ALD and introduce many methods of SiO2 ALD. Subsequently, theoretical advances concerning reaction mechanisms of SiO2 ALD are summarized. The related catalysis phenomena are highlighted, and their possible applications are speculated upon. Finally, a conclusion and perspective on the catalysis in the ALD growth of SiO2 is provided. It is expected that theoretical research on SiO2 ALD will enhance our comprehension of the chemistry and catalysis pertaining to ALD, provide a guide for the design of more effective Si precursors for SiO2 ALD, and lead to further improvement in the ALD preparation of other oxides and their nanolaminates.