Mixed Amido/Imido/Guanidinato Complexes of Tantalum: Effects of Ligand Substitution on Thermal Properties

Baunemann, Arne; Winter, Manuela; Csapek, Karoly; Gemel, Christian; Fischer, Roland A.

doi:10.1002/ejic.200600653

Cited by 21 publications

(23 citation statements)

References 25 publications

(7 reference statements)

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“…They attributed the deviation of the volatility from different molecular masses with regard to other ligands studied to the dispersion forces between the molecules modeled by a combination of intermolecular van der Waals interactions and the degree of branching of the alkyl ligand. In addition, Fischer and co-workers studied the influence of substituents on nitrogen in the guanidinate ligands on volatility and concluded that the variation of substituent bonded directly to the chelate ring has a greater effect than those in the exocyclic environment, 37 which is consistent with our finding here. Further, it was proposed that the intermolecular interactions between the molecules in the solid state could be the cause for the different volatilities when different moieties such as i PrNCN i Pr and CyNCNCy are present, although the contribution from the difference on molecular masses can not be excluded in their studies.…”

Section: Resultssupporting

confidence: 92%

New Tantalum Amido Complexes with Chelate Ligands as Metalorganic (MO) Precursors for Chemical Vapor Deposition (CVD) of Tantalum Nitride Thin Films

Chen¹,

Xu²,

Baum³

et al. 2009

Chem. Mater.

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Four new tantalum amido precursors (η 2 -RN(CH 2 ) n NR)Ta(NMe 2 ) 3 (where R=Me, n=2, 1; R= Et, n = 2, 2; R = Me, n = 3, 3; R = Et, n = 3, 4) with chelate diamide ligands and one new tantalum amido precursor (η 2 -t BuNC(NMe 2 )NEt)Ta(NMe 2 ) 4 ) (5) with a chelate guanidinate ligand were prepared and characterized. Their thermal behavior, especially (NMe 2 ) 3 Ta(η 2 -MeN(CH 2 ) 2 NMe) (1), were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) experiments to demonstrate the enhancement of their thermal stability and preservation of the volatility as metalorganic chemical vapor deposition (MOCVD) precursors as compared to Ta-(NMe 2 ) 5 (PDMAT). Introduction of the asymmetric chelate guanidine ligand in complex 5 gave improved volatility as compared with its known isomer [(η 2 -i PrNC(NMe 2 )N i Pr)Ta(NMe 2 ) 4 (6). The crystal structures of 5 and 6 were measured to investigate the correlation between the volatility and intermolecular interactions. The MOCVD of tantalum nitride thin films was successfully achieved using 1. The films are based on field emission scanning electron microscopy (FESEM) and show good adhesion properties. Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS) data suggest that the film deposited using 1 at 500°C under ammonia has a composition of TaN 1.22(0.14 with negligible carbon and oxygen levels. It also shows low resistivity of 1.4 Â 10 3 μΩ cm on SiO 2 /Si and broad X-ray diffraction (XRD) peaks for the stoichiometric cubic refractory TaN, indicating the potential of 1 becoming an alternative MOCVD precursor for barrier applications.

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Section: Resultssupporting

confidence: 92%

New Tantalum Amido Complexes with Chelate Ligands as Metalorganic (MO) Precursors for Chemical Vapor Deposition (CVD) of Tantalum Nitride Thin Films

Chen¹,

Xu²,

Baum³

et al. 2009

Chem. Mater.

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“…For the SEM image, XRD pattern and SNMS diagram see the ESI. † As observed and discussed in the case of related tantalum amido/imido complexes, 10 we expected to find these high carbon levels. The carbon incorporation is most likely caused by insertion of Nb into a C-H bond of methyl amido groups during the decomposition of the precursors in the absence of ammonia.…”

Section: Mocvd Experiments Using [Nb(nme 2 ) 3 (N-t-bu)] (1)supporting

confidence: 56%

“…The 1D routine 1 H and 13 C NMR spectra of the hexacoordinated complexes 3-6 are rather complex with partly overlapping groups of signals and are expectedly very similar to the corresponding tantalum congeners which have been extensively discussed in earlier reports. 10 Nevertheless, some differences in the 13 C NMR spectra should be pointed out for 3 as a representative example of the series. In contrast to the related tantalum compound, the spectra of the niobium complexes in general show very broad signals for the carbons directly bound to the Nb-N unit.…”

Section: Resultsmentioning

confidence: 99%

“…In general the bonding parameters are expectedly rather similar to the corresponding tantalum compounds. 10 The hexa-coordinated complex 3 exhibits the nitrogen atoms around the niobium in distorted octahedral fashion (Fig. 2).…”

Section: Crystallographic Studies Of 3 Andmentioning

confidence: 99%

“…9 The structurally much more complex mixed-ligand amido/imido/guanidinato tantalum compounds have been successfully used for TaN deposition. 10 Cubic, conductive and almost carbon-free TaN films were obtained even in the absence of additional nitrogen sources such as ammonia. We were thus led to look at the respective precursor chemistry of niobium nitride, which is expected to show similar characteristics as the tantalum case.…”

Section: Introductionmentioning

confidence: 99%

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Mixed amido/imido/guanidinato complexes of niobium: potential precursors for MOCVD of niobium nitride thin films

et al. 2008

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Novel mixed amido/imido/guanidinato complexes of niobium are reported. The complexes were synthesized by insertion of two equivalents of di-isopropylcarbodiimide (i-Pr-cdi) or bis-cyclohexylcarbodiimide (Cy-cdi) respectively, into the niobium-amido bonds of [Nb(NR(2))(3)(N-t-Bu)] (, R = Me; , R = Et) starting out from [NbCl(3)(N-t-Bu)(py)(2)] and the respective LiNR(2) reagent (py = pyridine). Four representative examples of these mixed ligand amido/imido/guanidinato compounds were synthesized and were characterized by (1)H-NMR, (13)C-NMR, (15)N-NMR, CHN-analysis, mass spectrometry and infra-red spectroscopy. The molecular structures of [Nb(NR(2)){eta(2)-(i-Pr-N)(2)C(NR(2))}(2)(N-t-Bu)] (, R = Me; , R = Et) in the solid state were determined by single-crystal X-ray diffraction studies and are discussed together with the molecular structure of the starting compound [Nb(NMe(2))(3)(N-t-Bu)] (). The thermal properties of the new compounds depend on the substitution at the guanidinato ligand. Complexes of i-Pr-cdi are significantly more volatile than complexes of Cy-cdi as revealed by thermogravimetric analysis. Preliminary experiments using as a single-molecule source for metal-organic chemical vapour deposition (MOCVD) in the absence of ammonia indicate the formation of the stoichiometric, and surprisingly carbon-free, cubic niobium nitride phase.

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Tantalum

Cook

2021

Comprehensive Coordination Chemistry III

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Mixed Amido/Imido/Guanidinato Complexes of Tantalum: Effects of Ligand Substitution on Thermal Properties

Cited by 21 publications

References 25 publications

New Tantalum Amido Complexes with Chelate Ligands as Metalorganic (MO) Precursors for Chemical Vapor Deposition (CVD) of Tantalum Nitride Thin Films

New Tantalum Amido Complexes with Chelate Ligands as Metalorganic (MO) Precursors for Chemical Vapor Deposition (CVD) of Tantalum Nitride Thin Films

Mixed amido/imido/guanidinato complexes of niobium: potential precursors for MOCVD of niobium nitride thin films

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