Direct liquid injection metal-organic chemical vapor deposition of HfO2 thin films using Hf(dimethylaminoethoxide)(4)

Abstract

Hf(OCH2CH2NMe2)(4), [Hf(dmae)(4)] (dmae = dimethylaminoethoxide) was synthesized and used as a chemical vapor deposition precursor for depositing Hf oxide (HfO2). Hf(dmae)(4) is a liquid at room temperature and has a moderate vapor pressure (4.5 Torr at 80 degreesC). It was found that HfO2 film could be deposited as low as 150 degreesC with carbon level not detected by X-ray photoelectron spectroscopy. As deposited film was amorphous but when the deposition temperature was raised to 400 degreesC, X-ray diffraction pattern showed that the film was polycrystalline with weak peak of monoclinic (020). Scanning electron microscope analysis indicated that the grain size was not significantly changed with the increase of the annealing temperature. Capacitance-voltage measurement showed that with the increase of annealing temperature, the effective dielectric constant was increased, but above 900 degreesC, the effective dielectric constant was decreased due to the formation of interface oxide. For 500 Angstrom thin film, the dielectric constant of HfO2 film annealed at 800 degreesC was 20.1 and the current-voltage measurements showed that the leakage current density of the HfO2 thin film annealed at 800 degreesC was 2.2 x 10(-6) A/cm(2) at 5 V. (C) 2003 Elsevier B.V. All rights reserved.