Atomic layer deposition of TiO₂ from TiCl₄ and O₃

Atomic layer deposition (ALD) of thin films from TiCl₄ and O₃ on Si(100) substrates was investigated. The growth of TiO₂ was obtained at substrate temperatures of 225–600 °C from these hydrogen-free precursors. Formation of anatase phase in the films was observed at 250–600 °C. In addition, the rutile phase was revealed in thicker films deposited at 600 °C. Compared to the well studied TiCl₄–H₂O ALD process the TiCl₄–O₃ process allowed higher growth rate at 275–600 °C. In addition, relatively low surface roughness was obtained for thicker (> 50 nm) films of the anatase structure deposited from TiCl₄ and O₃ at 350–400 °C. Therefore TiCl₄ and O₃ appeared to be a good precursor combination for ALD of TiO₂, particularly for applications that require low concentration of hydrogen contamination. - Highlights: • Thin films were grown from TiCl₄ and O₃ on Si substrates by atomic layer deposition. • The growth of TiO₂ was obtained at temperatures 225–600 °C. • Growth rates up to 0.07 nm per cycle were observed. • Films with relatively smooth surface were obtained at 350–500 °C