Tungsten imido complexes as precursors to tungsten carbonitride thin films

Abstract

Thin films of tungsten carbonitride have been formed on glass by low-pressure chemical vapour deposition (LP)CVD at 550 degrees C from four closely related precursors: [W(mu-N(t)Bu)(N(t)Bu)Cl(2)(H(2)N(t)Bu)](2), [W(N(t)Bu)(2)Cl(2)(TMEDA)] (TMEDA = N,N,N',N'-tetramethylethylenediamine), [W(N(t)Bu)(2)Cl(2)(py)(2)] (py = pyridine) and [W(N(t)Bu)(2)Cl(N{SiMe(3)}(2))]. The grey mirror-like films were grown with a nitrogen or ammonia bleed gas. In all cases the chlorine content of the deposited films was less than 1 at% and the oxygen content of the films was lower for those grown using ammonia. Surprisingly, the use of ammonia did not significantly change the carbon content of the resulting films. Despite the coordination environment around the metal being essentially the same and the materials having a comparable volatility, some differences in film quality were observed. The films were uniform, adhesive, abrasion resistant, conformal and hard, being resistant to scratching with a steel scalpel. X-Ray powder diffraction patterns of all the films showed the formation of beta-WN(x)C(y). As a comparison the aerosol-assisted chemical vapour deposition (AA)CVD of [W(mu-N(t)Bu)(N(t)Bu)Cl(2)(H(2)N(t)Bu)](2) was investigated and amorphous tungsten carbonitride films were deposited.

Synthesis of Mono‐Imido Tungsten Complexes Directly from WCl6

“…The complexes were prepared as described in scheme 1. The reaction between WCl 6 and N ‐ tert ‐butyltrimethylsilylamine to yield [W(μ‐N t Bu)(N t Bu)Cl 2 (H 2 N t Bu)] 2 has been reported previously . To control the number of tungsten‐imido bonds in the complex, we introduced excess pyridine to the reaction mixture, prior to the addition of N ‐ tert ‐butyltrimethylsilylamine.…”

“…This requires development of new precursors of metal‐organic nature and mild reaction by‐products. As a result, several tungsten complexes of nitrogen‐bound ligands (including amide, imide, hydrazido, amidinate, and guanidinate ligands) as single‐source precursors were developed . These precursors afforded halogen‐ and oxygen‐free tungsten nitride or tungsten carbonitride films when used in the ALD/CVD process in the presence of appropriate reductive gases (H 2 or NH 3 ).…”

Investigation of New 2,5‐Dimethylpyrrolyl Titanium Alkylamide and Alkoxide Complexes as Precursors for the Liquid Injection MOCVD of TiO2

“…TGA data provide an indication of the volatility and decomposition characteristics of a complex. [39] Complexes (2) and (3) show a significant loss of mass over the temperature range $100 À 260 8C and $100 À 240 8C, respectively. In each case, a significant amount of residue (5.7 À 6.0%) remained, probably due to the formation of TiO 2 .…”

Synthesis of Zirconium Guanidinate Complexes and the Formation of Zirconium Carbonitride via Low Pressure CVD

“…38 This study examines and compares two novel zirconium guanidinate compounds: [ZrCp′{η 2 -( i PrN) 2 CNMe 2 } 2 Cl] (1) and [ZrCp′ 2 {η 2 -( i PrN) 2 CNMe 2 }Cl] (2) (Cp′ ) monomethylcyclopentadienyl) as potential LPCVD precursors to zirconium carbonitride.…”