Thin Solid Films, Vol.517, No.19, 5695-5699, 2009
Atomic layer deposition of an HfO2 thin film using Hf(O-iPr)(4)
A thin film of hafnium dioxide (HfO2) was formed on the surface of Si(100) by atomic layer deposition (ALD) using Hf(O-iPr)(4) (Hf(OCH(CH3)(2))(4), hafinium tetrakis-iso-propoxide) as an Hf source and O-2 as an oxidant. The temperature window of the process was 250-350 degrees C, which is about 100 degrees C lower than that of a process using Hf(O-tBu)(4) as a source. This result was in accordance with the decomposition characteristics of the Hf precursor, as investigated by the temperature-programmed decomposition of the compound in an ultra-high vacuum and by thermogravimetric analysis in air. The thickness of a film deposited under the above conditions increased in proportion to the ALD cycles, indicating that the film-growth rate per cycle remained nearly constant during the process. The deposited film consisted of a monoclinic crystal phase included in an amorphous matrix, which was confirmed by X-ray diffraction. The film showed an equivalent-oxide thickness (EOT) of 2.1 nm and a leakage current density of 8.9 x 10(-6) A/cm(2) at -1 V. The leakage current was three orders of magnitude lower than that Of SiO2 with the same EOT. (C) 2009 Elsevier B.V. All rights reserved.