Zirconocene Alkoxides, Promising Precursors for MOCVD of Zirconium Dioxide Thin Films

Abstract

Some new volatile bis-cyclopentadienyl zirconium alkoxides of the type Cp2Zr(OR)(OtBu) (R = iPr, Et, Me) is synthesized by the reaction of the corresponding KOR with the intermediate Cp2ZrCl(OtBu). Moreover, an alternative and convenient synthesis of Cp2Zr(OtBu)2, based on the reaction of Cp2ZrCl2 with an excess of tert-butanol and triethylamine, is reported. The obtained compds. are identified by chem. analyses, thermogravimetric measurements, IR (IR), NMR (NMR) spectroscopy, and mass spectrometry (MS). Furthermore, a crystallog. study of Cp2ZrCl(OtBu) is also reported. Cp2Zr(OtBu)2 and Cp2Zr(OiPr)(OtBu) are then used for depositing zirconia thin films of high quality and purity on Si(100) and stainless steel AISI 316 substrates by metal-organic (MO)CVD. The microstructure and compn. of the deposits are investigated by X-ray diffraction (XRD) and secondary ion mass spectrometry (SIMS), while their hardness and elastic recovery on the AISI 316 substrate are measured using load-depth nano-indentation tests.The outcomes are consistent with a significant increase in the Berkovich hardness of the coated samples compared to that of bulk AISI 316

Investigation of Optical, Electrical, and Mechanical Properties of MOCVD‐grown ZrO2 Films

“…Recently, Sartori et al reported a nano‐indentation hardness of 6 to 10 GPa for ZrO 2 thick film (2 μm) on a stainless‐steel substrate prepared by MOCVD from a zirconium alkoxide precursor. It is not straightforward to make a direct comparison between the hardness values reported by Sartori et al with our values but, generally, we could take the hardness value in indentation depth of 1200 nm as reported by Sartori et al to compare with our hardness values on thin (400 nm) films of ZrO 2 ; in both cases, the hardness values were about 6 GPa.…”

“…For MOCVD, the film properties are strongly dependent on the precursors employed. Numerous references can be found in the literature on the use of chlorides, nitrates, alkoxides, diketonates, fluorinated diketonates, cyclopentadienyls, etc., however some of these precursors suffer from certain drawbacks. The alkyl amides of Zr are another class of compounds that are widely used for the ALD of ZrO 2 thin films, but less investigated for MOCVD applications since they are extremely sensitive to air and moisture, and have lower thermal stability.…”

“…Several deposition techniques, such as sputtering, pulse laser deposition (PLD), CVD, and atomic layer deposition (ALD), have been adopted to fabricate ZrO 2 thin films . Among these techniques, MOCVD offers distinct advantages in terms of large‐area growth with high growth rates, good composition control, and conformal coverage of substrate with complex topographies.…”

Multicomponent Mechanochemical Synthesis of Cyclopentadienyl Titanium tert-Butoxy Halides, CpxTiXy(OtBu)4–(x+y) (x, y = 1, 2; X = Cl, Br)

“…16 h) and even then may be incomplete, 47 and for the synthesis of the tert -butoxy derivative Cp 2 TiCl(O t Bu) ( 3 ), we investigated halide metathesis instead. This approach has been used to form Cp 2 ZrCl(O t Bu) in THF, 23 although the solution route fails for Cp 2 HfCl(O t Bu). 26f Mechanochemical activation works successfully with both of the heavier group 4 metals and it was adopted for the preparation of 3 .…”

“…26f Similarly, the reaction of Cp 2 ZrCl 2 and (Li or Na)[O t Bu] yields an inseparable mixture of Cp 2 ZrCl(O t Bu) and Cp 2 Zr(O t Bu) 2 , even with the use of more than 2 equiv of the alkoxide. 23…”