ZIRCONIUM CYCLOPENTADIENYLS ALKYLS

Fig. TGA of Cp-substituted Dimethylzirconocenes Zr(RCp)2Me2 (R= H, Me, Et, tBu)

Zirconium bis-alkylcyclopentadienyls bis-alkyls (h5-C5H4R)2ZrR´2 (R = H, CH3, …; R´ = single-bonded organic radicals, such as CH3-, C6H5-, C6F5-, …) are colorless to yellow-orange solids, sublimable.and soluble in most organic solvents. These are 16-valnce electron compounds, more reactive than (h5-C5H4R)ZrCl2 due to presence of Zr-CR bonds, with R’ = acetylide fairly stable (can be handled under air),

Zirconium bis-alkylcyclopentadienyls bis-alkyls (h5-C5H4R)2ZrR´2 are synthesized by metathesis reaction between bis-alkylcyclopentadienylzirconium bis-halides with 2 equivalents of lithium alkyls or alkylmagnesiumbromides:

 (h5-C5H4R)2ZrCl2 + 2 LiR’ (or 2 BrMgR’) -> (h5-C5H4R)2ZrR’2 + 2 LiCl  (or 2“BrMgCl”)

Dimethylzirconium bis(alkylcyclopentadienyl) compounds (ZrMe2(RCp)2, R=H, Me, Et, tBu) were considered as potential precursors for ALD of Zr-contaning thin films. They have relatively low volatility and give high residues in TGA, thus, thus, were considered to be not not promising as Zr precursors for high-temperature ALD.

ZrMe2Cp2 was applied for the MOCVD growth of ZrO2 films (see below).

Dimethylzirconium bis (cyclopentadienyl) (dimethylzirconocene) ZrMe2(Cp)2

Fig. Formula of dimethylzirconocene

ZrMe2Cp2 for ZrO2 (Mg or Ca-doped) by MOCVD

ZrMe2Cp2 was applied for the MOCVD growth of ZrO2 films stabilized in the cubic-fluorite phase by Mg or Ca (with Mg(MeCp)2 , Mg(thd)2(TMEDA), Ca(thd)2(triglyme) as stabilizing element sources). Colorless crack-free adherent films were obtained on fused quartz at 500°C. Complete stabilization was achieved with Mg content 12 to 30 at.%. and Ca content from 17 to 38 at.%. The microstructure and chemical composition of the grown layers was investigated by the combined use of XRD, XPS and EDXS. [162]

Dimethylzirconium propane-2,2-dicyclopentadienyl [(Cp2CMe2)ZrMe2]

Ansa-metallocene zirconium alkyl precursor [(Cp2CMe2)ZrMe2] was applied for the growth of thin ZrO2 films by liquid injection MOCVD (at 400–650 °C, with O2 oxidant) and ALD (at 175–350 °C, with ozone O3 as oxygen source). ZrO2 films grown by MOCVD were crystallized in tetragonal phase, according to XRD. Residual carbon was present in all the films (according to Auger electron spectroscopy); however the layers deposited by MOCVD contained more C contamination (2.4–17.0 at.%) compared to those obtained by ALD (1.8–2.8 at.%). The dielectric properties of ZrO2 grown by ALD were evaluated using [Al/ZrO2/n-Si] metal oxide semiconductor capacitor (MOSC) structures: the films had low current leakage densities (<6 × 10−7 A cm−2 at ±2 MV cm−1). [[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” 

ZrMe2Cp2 for Zr-doped InP by MOCVD

Dimethylzircocene. ZrMe2Cp2 was applied as as organometallic dopant for the LP-MOCVD growth of Zr-doped InP layers (as an alternative to Fe-doped semiinsulating InP, which was shown to lose its semiinsulating character in contact with p+-InP:Zn substrate). [[i]]

[i] T. Wolf, A. Krost, D. Bimberg, F. Reier, P. Harde, J. Winterfeld, H. Schumann, J. Cryst. Growth, 1991, Vol.107, Iss. 1–4, p. 381-385 , « Transition metal doping of LP-MOCVD-grown InP », doi.org/10.1016/0022-0248(91)90490-V, https://www.sciencedirect.com/science/article/pii/002202489190490V

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