HAFNIUM CYCLOPENTADIENYLS- ALKYLS-ALKOXIDES
Methylhafnium bis(methylcyclopentadienyl) methoxide HfMe(MeCp)2(OMe)]
Methylhafnium bis(methylcyclopentadienyl) methoxide HfMe(MeCp)2(OMe) (HfD-04), a novel non-amide precursor, was applied as precursor for the ALD growth of HfO2 films, and compared in terms of purity of the films (N, H, C residuals) with dimethylhafnium bis(methylcyclopentadienyl) (HfD-02, HARALD1) and conventional amide pecursors (TEMAH, TDEAH). HfMe(MeCp)2(OMe) has shown ideal self-limiting ALD deposition behavior at temperatures as high as 450°C with negligible incorporation of impurities within the layers (Fig.). [[i]] The use of amides is limited because of their thermal instability at the high temperature of vapor transport or deposition temperature, which is typically <300°C.
[i] R. Kanjolia, Semiconductor International, 12/1/2007
Bis(methylcyclopentadienyl)methylhafnium methoxide HfMe(CpMe)2(OMe), in combination with O3 as oxygen source, was used as precursor for the deposition of high-quality dense insulating HfO2 films on semiconductor or metallic substrates by ALD[[ii]
[ii] Tamm, Aile, URI: http://hdl.handle.net/10062/15838, Date: 2010-10-26, « Atomic layer deposition of high-permittivity insulators from cyclopentadienyl-based precursors »
MethylhafniuMethylhafnium bis(methylcyclopentadienyl) isopropoxide HfMe(MeCp)2(OiPr)], Methylhafnium bis(methylcyclopentadienyl) methoxymethylpropanolate HfMe(MeCp)2(mmp)]
Methylhafnium bis(methylcyclopentadienyl) isopropoxide HfMe(MeCp)2(OiPr)],
Methylhafnium bis(methylcyclopentadienyl) methoxymethylpropanolate HfMe(MeCp)2(mmp)]
New alkylhafnium alkoxide-cyclopentadienyl precursors [(MeCp)2HfMe(OiPr)] and [(MeCp)2HfMe(mmp)] (mmp = OCMe2CH2OMe) have been applied for the growth of thin films of HfO2 by liquid injection MOCVD and ALD.
Methylhafnium bis(methylcyclopentadienyl) isopropoxide HfMe(MeCp)2(OiPr)], Methylhafnium bis(methylcyclopentadienyl) methoxymethylpropanolate HfMe(MeCp)2(mmp)]
Methylhafnium bis(methylcyclopentadienyl) isopropoxide HfMe(MeCp)2(OiPr)],
Methylhafnium bis(methylcyclopentadienyl) methoxymethylpropanolate HfMe(MeCp)2(mmp)]
New alkylhafnium alkoxide-cyclopentadienyl precursors [(MeCp)2HfMe(OiPr)] and [(MeCp)2HfMe(mmp)] (mmp = OCMe2CH2OMe) have been applied for the growth of thin films of HfO2 at 400–650 °C by liquid injection MOCVD, and at 300–450 °C by ALD approach. Both [(MeCp)2HfMe(OiPr)] and [(MeCp)2HfMe(mmp)] evaporate at moderate temperatures, making them well-suitable precursors for MOCVD and ALD applications. According to XRD, the grown HfO2 layers were amorphous, upon annealing over 700 °C in dry air crystallizing into the α- or monoclinic phase. MOCVD-deposited HfO2 films generally contained more C impurity than ALD-grown layers ; according to AES residual carbon was present at 0–5 at.%. [Al/HfO2/SiO2/n-Si] MOS capacitor structures with various HfO2 thicknesses ranging from 1.7 nm to 102 nm were used for the evaluation of the dielectric properties of the as-deposited HfO2 films. The calculated permittivity (ϵox) for the ALD-grown HfO2 films was ∼ 14 with [(MeCp)2HfMe(OiPr)] precursor, amd ∼10 with [(MeCp)2HfMe(mmp)] precursor (assuming the presence of a 1 nm native SiO2 interlayer). ALD-deposited HfO2 films had EOT of 2.5 nm (for [(MeCp)2HfMe(OiPr)] precursor) and 0.78 nm (for [(MeCp)2HfMe(mmp)] precursor). The leakage current density for a film grown using [(MeCp)2HfMe(OiPr)] by ALD was very low (<10–6 A cm–2) up to 2.5 MV cm–1, while for the MOCVD-grown films it was significantly higher. [[i]]
[i] R. O'Kane, J. Gaskell, A. C. Jones, P. R. Chalker, K. Black, M. Werner, P. Taechakumput, S. Taylor, P. N. Heys, R. Odedra , “Growth of HfO2 by Liquid Injection MOCVD and ALD Using New Hafnium-Cyclopentadienyl Precursors”, Chemical Vapor Deposition, Volume 13, Issue 11, pages 609–617, November, 2007
Methylhafnium methoxide propane-2,2-dicyclopentadienyl [(Cp2CMe2)HfMe(OMe)]
Ansa-metallocene precursor methylhafnium methoxide propane-2,2-dicyclopentadienyl [(Cp2CMe2)HfMe(OMe)] (compared to dimethylhafnium analogue [(Cp2CMe2)HfMe2]– see corresponding section), has been applied as precursor for the deposition of HfO2 layers by liquid injection MOCVD and ALD using O2 (MOCVD) or O3 (ALD) as oxygen source. The chelating [Cp2CMe2] ligand leads to a pseudo-four-coordinate distorted tetrahedral geometry around the central Hf atom, in agreement with predictions of Density Functional Theory (DFT). The HfO2 films were grown by MOCVD in the temperature range 400–650 °C and by ALD at 175–350 °C temperatures. The MOCVD-deposited HfO2 films were X-Ray amorphous, the residual carbon was present in all the films according to AES (2.4–17.0 at.% in the films grown by MOCVD and 1.8–2.8 at.% in he layers deposited by ALD.
The dielectric properties of ALD-grown HfO2 layers was evaluated by [Al/HfO2/n-Si] metal oxide semiconductor capacitor (MOSC) structures ; low current leakage density of 6 ×10−7 Acm−2 at ±2 MVcm−1 was determined.[i]
[i] Kate Black, H.C. Aspinall, Anthony C. Jones, Katarzyna Przybylak, John Bacsa, Paul R. Chalker, S.Taylor, Ce Zhou Zhao, S.D. Elliott, A.Zydord, Peter N. Heyse , J. Mater. Chem., 2008,18, 4561-4571, DOI: 10.1039/B807205A
http://pubs.rsc.org/en/content/articlelanding/2008/jm/b807205a#!divAbstract
Deposition of ZrO2 and HfO2 thin films by liquid injection MOCVD and ALD using ansa-metallocene zirconium and hafnium precursors
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