Ligand intermediates in the chemical vapor deposition of metal disulfide, metal diselenide, and metal nitride thin films

Early transition metal dichalcogenide and nitride thin films are extremely important in industry. Metal dichalcogenides are useful as solid-state lubricants and as cathode materials in lithium batteries. Titanium nitride has many uses, including tool coatings, decorative gold coatings, and conductive layers and barrier materials in microelectronics. Coatings of these materials can be obtained by Chemical Vapor Deposition (CVD) techniques. Despite the popularity of this deposition technique, very little is known about the chemistry involved. A careful study of the range of ligand intermediates that can be supported at a metal center should illustrate broad chemical principles that can be applied to other film deposition systems. Such studies should be of fundamental importance to the continuing and expanding use of CVD processes. The research described herein is aimed at these goals.;This dissertation describes an investigation of chemical reactions that are relevant to film depositions through the design and development of molecular precursors to metal disulfides, metal diselenides, and metal nitrides. The gas phase reaction between titanium tetrachloride and isopropyl thiol and the resulting titanium disulfide films are discussed. The coordination chemistry of titanium tetrahalides, niobium pentahalides, and tantalum pentahalides with dialkyl disulfides results in unexpected complexes. Their evaluation as precursors to titanium disulfide, niobium disulfide, and tantalum disulfide are described. Also presented are titanium tetrachloride adducts of organoselenium donors that function as precursors to titanium diselenide thin films. A model study of hydrogen-substituted imido complexes, which are proposed intermediates in CVD processes to titanium nitride thin films, is discussed. In addition, the coordination chemistry of titanium tetrachloride with 1,1-disubstituted hydrazines is explored. The importance of these complexes in the CVD of titanium nitride is discussed.