Tungsten bis(tert-butylimide) (dimethylamide) (diisopropyldimethylguanidinate) [W(NtBu)2(NMe2){(iPrN)2CNMe2}] was proposed as potential single source precursor for the growth of tungsten nitride thin films by MOCVD. [W(NtBu)2(NMe2){(iPrN)2CNMe2}] was synthesized by substitution of the chloro ligand in the starting compound [W(NtBu)2(Cl){(iPrN)2CNMe2}] by a dimethylamido group. [W(NtBu)2(NMe2){(iPrN)2CNMe2}] was characterized by elemental analysis, 1H NMR, 13C NMR, IR, and EI-MS. Thermogravimetric and differential thermal analysis were applied to investigate the precursor thermal properties.
[W(NtBu)2(NMe2){(iPrN)2CNMe2}] (and for comparison it analogue with amide group replaced by hydride [W(NtBu)2(H){(iPrN)2CNMe2}] ) was tested as precursor for the growth of WNx thin films by MOCVD (as single source precursor (SSP) or with addition of NH3 as co-reactant). The obtained layers were characterized by XRD and SEM, layer composition was depth-profiled by secondary neutron mass spectroscopy; it was determined that layers grown without NH3 had surprisingly low N levels, indicating that [W(NtBu)2(NMe2){(iPrN)2CNMe2}] is not suitable as SSP precursor for pure WNx films. The carbon content in the layers decreased significantly and crystalline β-W2N were obtained, when NH3 was used as a co reactant gas. [W(NtBu)2(NMe2){(iPrN)2CNMe2}] yielded lower C contents than films obtained from hydrido compound [W(NtBu)2(H){(iPrN)2CNMe2}] for the WNx layers grown in the presence of NH3.[i]
[i] D. Rische, H. Parala, E. Gemel, M. Winter, R.A. Fischer, Chem. Mater. 2006, 18, 25, 6075–6082, « New Tungsten(VI) Guanidinato Complexes: Synthesis, Characterization, and Application in Metal−Organic Chemical Vapor Deposition of Tungsten Nitride Thin Films », https://doi.org/10.1021/cm061999d , https://pubs.acs.org/doi/abs/10.1021/cm061999d