Pyridine-Catalyzed\nAtomic Layer Deposition of SiO₂ from Hexachlorodisilane\nand Water: An In Situ Mechanistic\nStudy

Abstract

Pyridine-catalyzed atomic layer deposition (ALD) of SiO₂ from hexachlorodisilane and water was studied by in situ\nanalyses\nusing Fourier-transform infrared spectrometry and a quartz crystal\nmicrobalance. Although it has been observed that ALD SiO₂ can grow even when only one half-reaction is catalyzed, typical\nself-limiting growth of SiO₂ by catalytic ALD has been\nachieved when both half-reactions are catalyzed by pyridine. The in\nsitu analyses revealed that the unexpected growth of SiO₂, when only one half-reaction was catalyzed, was caused by the presence\nof residual pyridine that had not yet desorbed from the previous half-reaction.\nThe retardation of catalyst desorption was more prominent on the OH-terminated\nSiO₂ surface than on the Cl-terminated surface, which is\nrelated to the significantly higher desorption energy of pyridine\nspecies on the hydroxyl surface calculated using density functional\ntheory.