HAFNIUM (IV) DIALKYLAMIDINATES
Hafnium (IV) tetrakis(N,N’-dimethylbutyramidinate)
Fig. Molecular structure of Hafnium (IV) tetrakis(N,N’-dimethylbutyramidinate)
Hafnium (IV) tetrakis(N,N’-dimethylbutyramidinate) (or hafnium (IV) tetrakis(N,N’-dimethylpropionamidinate) ) Hf(N,N’-Me2-BMD)4 is a liquid at room temperature and can be purified by distillation instead of sublimation. Its T1/2 value is 252° C; it evaporates leaving a negligible residue. [[i][PS1] ]
Characterisation: 1H NMR (benzene-d6, ppm): 3.15 (s, 24, NCH3), 2.13 (t, 8, J=8.0 Hz, CCH2CH2CH3), 1.49 (m, 8, CCH2CH2CH3), 0.89 (t, 12, J=6.8 Hz, CCH2CH2CH3). 13C NMR (benzene-d6, ppm): 178.87 (s, CCH2CH2CH3), 34.08 (s, NCH3), 26.29 (s, CCH2CH2CH3), 19.82 (s, CCH2CH2CH3), 14.41 (s, CCH2CH2CH3). Anal. Calcd. for C24H52HfN8: C, 45.67; H, 8.30; N, 17.75. Found: 45.31; H, 8.81; N, 17.61.
Synthesis:
- salt metathesis reaction using HfCl4 and lithium (N,N’-dimethylbutyramidinate) (which was in turn synthesized by reaction of LinBu and N,N′-dimethylbutyramidine in Et2O/hexane at −78° C).
- ligand exchange reaction between Hf(NMe2)4 and N,N′-dimethylbutyramidine.
The molecular structure of hafnium (IV) tetrakis(N,N’-dimethylbutyramidinate) was determined by single
crystal XRD. (Fig. )
[i] R.G. Gordon, J.-S. Lehn, H. Li, US Patent US7638645B2, 2009 , « Metal (IV) tetra-amidinate compounds and their use in vapor deposition », https://patents.google.com/patent/US7638645B2/en
Hf(N,N’-Me2-BMD)4 (+O3) for HfO2 by ALD
Tetrakis(N,N-dimethylbutyramidinato)hafnium(IV) (vapor dose 10 mmol/cm2) vaporized using direct liquid injection system at 200° C was introduced with an exposure of 10 Torr-sec into an ALD reactor at 400° C, alternately with 20 nmol/cm2 doses of O3 at an exposure of 10 Torr-sec. Thin HfO2 film was deposited conformally inside high aspect ratio (80:1) narrow holes.
Hf(N,N’-Me2-BMD)4 (+H2O) for HfO2 by ALD
Tetrakis(N,N-dimethylbutyramidinato)hafnium(IV) (vapor dose 10 mmol/cm2) vaporized using direct liquid injection system at 200° C , and H2O (vapor dose 20 nmol/cm2) were alternately introduced (both with an exposure of 10 Torr-sec) into an ALD reactor at 400° C. Thin HfO2 layers were conformally grown inside narrow holes with high aspect ratio (80:1).
Hf(N,N’-Me2-BMD)4 (+NH3) for HfNx by ALD
Tetrakis(N,N-dimethylbutyramidinato)hafnium(IV) vaporized using direct liquid injection system at 200° C (vapor dose 10 mmol/cm2) , and NH3 (vapor dose 20 nmol/cm2) were alternately introduced into an ALD reactor at 400° C (both with an exposure of 10 Torr-sec). Thin hafnium nitride HfNx layers were deposited conformally inside high aspect ratio (80:1) narrow holes.
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