Preparation and Properties of Aluminum Nitride Films Using an Organometallic Precursor

Abstract

Polycrystalline aluminum nitride films were deposited on silicon and silica substrates at 400°–800°C in a low pressure chemical vapor deposition system using the volatile organometallic precursor, . Under appropriate conditions of substrate temperature and growth rate, the films were transparent, smooth, and highly adherent to the substrate. Auger electron spectroscopy indicated that these films contained close to a one‐to‐one ratio of aluminum to nitrogen and relatively low concentrations of carbon and oxygen. X‐ray and electron diffraction studies showed that the 2H (hexagonal,; ) phase of aluminum nitride was the only crystalline product. Scanning and transmission electron microscopy indicated a dense, polycrystalline microstructure with an grain size range of 0.05–1.00 μm, depending on the deposition conditions. Films deposited on silica at or above 600°C were transparent in the visible and near infrared with an absorption edge of ca. 6.2 eV. Fourier transform infrared spectra of the films on silicon showed the characteristic Al‐N stretching vibration at with relatively weak and broad bands in the N‐H and C‐H stretching region. Current‐voltage and capacitance‐voltage measurements were performed on aluminum nitride films deposited on Si (100), yielding values for the dielectric constant, field breakdown strength, and resistivity. The effects of annealing in a nitrogen atmosphere up to 800°C were studied using UV‐visible and FTIR absorption spectroscopy. The rate of dissolution of the films in phosphoric acid was also determined. These results indicate that can be used as a single‐component precursor for the low pressure deposition of aluminum nitride films at temperatures as low as 500°C, and that the films obtained at or above 600°C have microstructural features and properties appropriate for microelectronic applications.