TUNGSTEN ALKYLIMIDES-ALKYLAMIDES
Bis(tert-butylimido)bis(tert-dimethylamido)tungsten W(=NtBu)2(NMe2)2
Fig. W(=NtBu)2(NMe2)2 - structural formula
Bis(tert-butylimido)bis(dimethylamido)tungsten W(tBuN)2 (NMe2)2 ( M =) is low viscosity non-corrosive liquid, boiling point 50°C / 0.05 Torr
W(tBuN)2(NMe2)2 has sufficient volatility at room temperature and was applied as W precursors for ALD growth of WN thin films.
W(=NtBu)2(NMe2)2 for WNx films by ALD
W(=NtBu)2(NMe2)2 has been applied tungsten precursor (combined with NH3 as N source) for the ALD growth of WN layers on Si, glass, quartz, glassy carbon, stainless steel, Al, Au, Cu substrates, the growth rate was 0.1nm/cycle. The deposited films had 100% step coverage in 200:1 ratio vias, the composition of the layers had W:N ratio 1:1 according to RBS. WNx layers as thin as 1.5 nm were demonstrated to be efficient barrier for Cu diffusion.[i]
[i] J. S. Becker, S. Suh, S. Wang, R. G. Gordon, Chem. Mater., 15, 2969 (2003)
W(=NtBu)2(NMe2)2 for WNx films by MOCVD
Tungsten bis(tertbutylimide) bis(dimethylamide) [W(NtBu)2(NMe2)2]) (and for comparison [W(NtBu)2(NMe2){(iPrN)2CMe}] ) was tested as MOCVD precursor for the deposition of WN thin films on Si (100) at 500–800 °C temperatures. WN layers deposited under single source precursors (SSP) conditions consisted of a mixture of WCx and WNx phases, whereas with addition of NH3, crystalline WN layers (according to XRD) were obtained at higher growth temperatures (T ≥ 600 °C). WN layers grown with NH3 had increased content of N, decreased C level and lower resistivity, compared to the films grown under SSP conditions (according to RBS, NRA and XPS).[i]
[i] N. B. Srinivasan, T. B. Thiede, T. de los Arcos, D. Rogalla, H.-W. Becker, A. Devi, R.A. Fischer, « MOCVD of tungsten nitride thin films: Comparison of precursor performance and film characteristics », Phys. Status Solid. A, 2014, Vol.211, Iss.2, p.260-266, https://onlinelibrary.wiley.com/doi/abs/10.1002/pssa.201330127
Bis(tert-butylimido)bis(tert-butylamido)tungsten W(=NtBu)2(NHtBu)2
Bis(tert-butylimido)bis(tert-butylamido)tungsten W(=NtBu)2(NHtBu)2 (M = ), bp. 50°C / 0.05 Torr).
W(=NtBu)2(NHtBu)2 complex is containing both W and N in the same molecule, and was applied as single-source precursor (not requiring an additional N source.), or as well with adiditon of NH3 as extra nitrogen source, for the deposition of thin WNx films by pyrolyzing the complex in the temperature range 450°C- 650 °C
W(=NtBu)2(NHtBu)2 for WNx films by MOCVD
W(=NtBu)2(NHtBu)2 was applied as single source precursor for the deposition of tungsten nitride layers on Si and glass substrates by cold wall LPCVD at 450-650°C growth temperature. The W(=NtBu)2(NHtBu)2 precursor was vaporized at 60-90°C temperature. Cubic polycrystalline WN0.7-1.8 were obtained (lattice param. 0.4154 nm) at growth rate 2-10 nm/min. The layers were characterized by XPS: BE W4f7/2 33.0, W4f5/2 35.0 eV, N1s 397.3 eV and SIMS: low C, O contamination was observed, WNx layer resistivity was 4300-620μΩ·cm (at deposition temperatures 500-650°C). Volatile by-products of the CVD process were identified as isobutylene, MeCN, HCN, NH3.[i]][[ii]
[i] H. T. Chiu, S. H. Chuang, Mater. Res., 8, 1353 (1993)
[ii] M. H. Tsai, S. C. Sun, H. T. Chiu, S. H. Chuang, Appl. Phys. Lett., 68, 1412, (1996)
W(=NtBu)2(NHtBu)2 for WNOx films by MOCVD
W(=NtBu)2(NHtBu)2 (in combination with NH3) was applied as precursor for the deposition of tungsten oxynitride WNO layers on Si, SiO2, glass, glassy carbon, Al, stainless steel substrates by LPCVD at growth temperatures 350-400°C. Layer composition was WN1.2O1.7-WN1.6O0.25, growth rates 0.6-4.1 nm/min, films were amorphous by XRD, smooth by SEM. Step coverage was 100% in 6:1 ratio vias. 45nm barriers were demonstrated to be efficient for Cu diffusion up to 600°C temperature [i]
[i] R. G. Gordon, J. Barton, S. Suh, MRS Symp. Proc., 2001 Spring, Symposium L, p..
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