Barium alkylcyclopentadienyls

In general, thermal decomposition and carbon incorporation are issues observed when using barium metallocene precursors in MOCVD applications

Barium bis(cyclopentadienyl) (barocene) BaCp2

Barium bis(cyclopentadienyl) (barocene) BaCp2 is polymeric, non-volatile and therefore not suitable for CVD applications.[[i]]

[i]K. Fichtel, Dissertationsschrift, Universität Hamburg 2004

Barium pentamethylcyclopentadienyl Ba(Me5Cp)2

Barium pentamethylcyclopentadienyl Ba(Me5Cp)2

Barium pentamethylcyclopentadienyl Ba(C5Me5)2 has been applied as a precursor growth of BaTiO3 films by ALD at temperatures ≤ 275°C, in combination with Ti(OiPr)4 and H2O as Ti and O sources, respectively. Significant decomposition of Ba(C5(CH3)5)2 was observed at higher growth temperatures, issues with reproducibility of composition and properties were found even at a depositions temperature of 275°C. [4]

Barium isopropylcyclopentadienyl Ba(iPrCp)2

Barium isopropylcyclopentadienyl Ba(iPrCp)2 , in combination with Y(iPrCp)3 and Cu(EtCp)(Et3P) precursors, has been applied for the deposition of high-temperature superconducting YBaCuO films by CVD at substrate temperature 800°C and reactor pressure 250 Torr. The carrier gas was hydrogen H2, the oxidizing agent was CO2/H2 mixture, mole fractions for Ba, Y and Cu precursors in the reactor ca. 1.5×10-3, 7.5×10-4 and 2.3×10-3, respectively ( . These mole fractions refer to bubbler temperatures at 75° C  and flow rates at 1000 sccm for Ba , 500 sccm for Y, and 20°C bubbler temperature/ flow rate 100 sccm for Cu copper precursor, and  the mole fraction of the oxidizing agent CO2/H2 in the reactor 10-2. The lines leading from the source to the reactor were kept at 80° C to avoid reactant condensation.. [[i]]

[i]Ahmet Erbil  “Chemical vapor deposition of mixed metal oxide coatings”,

 US 4927670 A, 1990

http://www.google.com/patents/US4927670

Barium bis(tri-tert-butylcyclopentadienyl) Ba(tBu3Cp)2

Ba(tBu3Cp)2 (+Ti(OMe)4) for BaTiO films by ALD

Barium bis(tri-tert-butylcyclopentadienyl) Ba(tBu3C5H2)2 , combined with titanium tetrakis(methoxide) Ti(OMe)4 as Ti precursor and H2O as O source) was applied as titanium precursor for the growth of barium titanate BaTiO layers by ALD at 340 °C. Binary reactions of Ba(tBu3C5H2)2 and H2O forming BaO films by ALD were first studied separately; the process included hydration/dehydration cycles strongly influenced by the growth temperature. When Ba(tBu3C5H2)2 – H2O growth cycles were mixed in optimal way with Ti(OMe)4 - H2O cycles, self-limiting growth of amorphous BaTiO films was achieved. Post-deposition annealing at 600 °C resulted in the crystallization of the as-deposited amorphous BaTiO films and increase of dielectric permittivities from 15 to 70. Charge density 1.9 μC cm–2 (equivalent oxide thickness of 1.8 nm) and leakage current density ≤ 1 × 10–7 A cm–2 at 1 V bias were obtained for 32 nm thick Ba–Ti–O film in a Pt electrode stack after annealing at 600 °C [[i]]

[i] M. Vehkamäki, T. Hatanpää, M. Ritala, M. Leskelä, S. Väyrynen, E. Rauhala, Chem. Vapor Dep., 2007, Vol.13, Iss.5, p.239-246, « Atomic Layer Deposition of BaTiO3 Thin Films—Effect of Barium Hydroxide Formation « , doi.org/10.1002/cvde.200606538, onlinelibrary.wiley.com/doi/abs/10.1002/cvde.200606538

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