ZIRCONIUM CYCLOPENTADIENYLS ALKYLS-ALKOXIDES
Methylzirconium bis(methylcyclopentadienyl) methoxide [ZrMe(MeCp)2(OMe)]
[ZrMe(MeCp)2(OMe)] for ZrO2 (Gd- or Er-doped) by ALD
Methylzirconium bis(methylcyclopentadienyl) methoxide ZrMe(CpMe)2(OMe))
(and for comparison (CpMe)2ZrMe2)) was applied as precursor for the preparation of high-quality dense dielectric ZrO2 films by ALD on semiconductor or metallic substrates, using ozone O3 as the oxygen source. High conformality (step-coverage) zirconia layers
were obtained on three-dimensional substrates In order to increase ability of metastable cubic/tetragonal ZrO2 phase to withstand post-deposition annealing procedure without transformation to lower-permittivity
monoclinic phase during fabrication of high-density capacitors, the prepared ZrO2 films were further Er, Gd-doped or nanolaminated with Gd2O3 and Er2O3. [[i]]
[i] A. Tamm, URI: http://hdl.handle.net/10062/15838, 2010-10-26, “Atomic layer deposition of high-permittivity insulators from cyclopentadienyl-based precursors”
[ZrMe(MeCp)2(OMe)] for LaxZr1-xO2- δ by MOCVD, ALD
Methylzirconium bis(methylcyclopentadienyl) methoxide [ZrMe(MeCp)2(OMe)],
combined with [La(iPrCp)3], was dissolved in toluene and applied as precursor for the growth of thin films of LaxZr1–xO2–δ (x = 0.09 – 0.77) by liquid injection MOCVD as well as ALD.
LaxZr1–xO2–δ films grown by ALD at 300 °C contained ~3.2–5.4 at.- % of C contamination, whilst films obtained by MOCVD at 400 °C had higher carbon levels (2.4
– 10.5 at.- %) , according to Auger electron spectroscopy. Films with lower La content (0.09-0.22) crystallized into cubic La-stabilized zirconia phase on annealing at 700 °C, whereas films with higher La fraction (x = 0.35-0.63)
remained X-Ray amorphous. The onset of crystallization of these films in general increased with the La content. For x = 0.35 (La%), crystallization to the cubic ZrO2 phase occurred at 800-900 °C. LaxZr1–xO2–δ films
grown by ALD demonstrated good dielectric properties with low hysteresis voltages, negligible flatband voltage shifts, k values 11 to 14 and leakage current densities of 0.53-2.6 × 10–6 A/cm2, while films grown by MOCVD had leakage current densities
0.83-1.1 × 10–6 A/cm2.[[i]]
[i] J. M. Gaskell, A. C. Jones, P. R. Chalker, M. Werner, H. C. Aspinall, S. Taylor, P. Taechakumput, P. N. Heys, Chem. Vap.Dep., 2007, Vol.13, Iss.12, pp. 684–690, “Deposition of Lanthanum Zirconium Oxide High-k Films by Liquid Injection ALD and MOCVD”
Methylzirconium propane-2,2-dicyclopentadienyl methoxide [(Cp2CMe2)ZrMe(OMe)]
Ansa-metallocene zirconium alkoxide complex [(Cp2CMe2)ZrMe(OMe)] was synthesized and tested as precursor for the deposition
of ZrO2 layers by liquid injection MOCVD (using O2 as oxygen source, at 400–650 °C growth temperature) and ALD (at 175–350 °C, with ozone O3 as oxidizer). The crystal structure of [(Cp2CMe2)ZrMe(OMe)]
was determined; it appeared to be mononuclear containing a chelating [Cp2CMe2] ligand leading to a pseudo-four-coordinate distorted tetrahedral geometry around the central Zr atom, in agreement with structure prediction from Density Functional Theory (DFT).
As determined by XRD, tetragonal phase ZrO2 films were obtained by MOCVD. The layers grown by ALD (1.8–2.8 at.%) had less residual carbon contamination versus those deposited by MOCVD (2.4–17.0 at.% C), as measured by AES. ZrO2 layers grown by
ALD had low current leakage densities (<6 × 10−7 A cm−2 at ±2 MV cm−1) in the [Al/ZrO2/n-Si] metal oxide semiconductor capacitor (MOSC)
structures [[i] ]
[i] K. Black, H.C. Aspinall, A.C. Jones, K. Przybylak, J. Bacsa, P.R. Chalker, S.Taylor, C. Zh. Zhao, S.D. Elliott, A.Zydord, P.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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