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Tungsten Allylimido Complexes Cl4(RCN)W(NC3H5) as Single-Source CVD Precursors for WNxCy Thin Films. Correlation of Precursor Fragmentation to Film Properties

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journal contribution
posted on 01.06.2005, 00:00 by Omar J. Bchir, Kelly M. Green, Hiral M. Ajmera, Elizabeth A. Zapp, Timothy J. Anderson, Benjamin C. Brooks, Laurel L. Reitfort, David H. Powell, Khalil A. Abboud, Lisa McElwee-White
A mixture of the tungsten allylimido complexes Cl4(RCN)W(NC3H5) (3a, R = CH3 and 3b, R = Ph) was tested as a single-source precursor for growth of tungsten nitride (WNx) or carbonitride (WNxCy) thin films. Films deposited from 3a,b below 550 °C contained amorphous β-WNxCy, while those deposited at higher temperatures were polycrystalline. Film growth rates from 3a,b ranged from 5 to 10 Å/min over a temperature range of 450−650 °C, and the apparent activation energy for film growth was 0.15 eV. A plot of the Ea values for deposition from Cl4(RCN)W(NR‘) [R‘ = Ph, iPr, allyl] against the N−C imido bond strengths for the analogous amines R‘NH2 is linear, implicating cleavage of the N−C bond as the rate-determining step in film growth. The correlation of mass spectral fragmentation patterns for Cl4(RCN)W(NR‘) with film properties such as nitrogen content supports the significance of facile N−C bond cleavage in film growth.