Atomic layer deposition of an HfO2 thin film using Hf(O-iPr)4 |
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| Authors: | Jeong Chan Kim Jung Shik Heo Yong Seok Cho Sang Heup Moon |
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| Affiliation: | 1. Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland;2. Accelerator Laboratory, Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Helsinki, Finland |
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| Abstract: | 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, hafnium tetrakis-iso-propoxide) as an Hf source and O2 as an oxidant. The temperature window of the process was 250–350 °C, which is about 100 °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 × 10? 6 A/cm2 at ? 1 V. The leakage current was three orders of magnitude lower than that of SiO2 with the same EOT. |
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