Post deposition annealing of aluminum oxide deposited by atomic layer deposition using tris(diethylamino)aluminum and water vapor on Si(100)

Thin stoichiometric aluminum oxide films were deposited using tris(diethylamino)aluminum precursor and water. Changes in aluminum oxide film and interfacial regions were studied after post deposition annealing under inert ambience at 600, 800 and 1000 °C using Fourier Transform InfraRed (FTIR) spectroscopy, X-ray Photoelectron Spectroscopy, and Scanning Transmission Electron Microscopy (STEM)/Electron Energy Loss spectroscopy (EELS) techniques. STEM/EELS analyses were also done on samples annealed in situ, i.e., inside the electron microscope at temperatures as high as 800 °C. Up to an annealing temperature of 600 °C, the atomic layer deposited alumina film was thermally stable and remained amorphous with no interfacial silica growth observed. After annealing at 800 °C for 5 min, the only change observed was a small increase in the interfacial layer thickness which was found to be mainly silicon oxide without any significant silicate content. Annealing at 1000 °C induced a significant increase in the interfacial layer thickness which consisted of a mixture of silicon oxide and aluminum silicate. The composition of the interfacial layer was found to change with depth, with silicate concentration decreasing with distance from the Si substrate. Also, the FTIR spectra exhibited strong absorption features due to Al-O stretching in condensed AlO₆ octahedra which indicate crystallization of the alumina film after annealing at 1000 °C for 5 min.