[(Benzene)(1,3-cyclohexadiene)Ru] was investigated as a designed metal-organic (MO) CVD precursor where the inherent structural and chemical features of the ligands help the formation of pure ruthenium films. The investigations have been performed with Si wafers as the substrate at a total gas pressure of 50 mbar, substrate temperature range of 200-450°C, and helium carrier gas velocity of 1.5 to 16.5 cm s -1 . The main focus was on the evaluation of the process parameters that promote the purity of the deposited ruthenium films without the help of a reactive gas component. The composition of the MOCVD exhaust gas was analyzed by gas chromatography (GC), and the deposited ruthenium films characterized by elastic recoil detection analyses (ERDA) to relate the carbon content of the films with the follow-up chemistry of the ligands. The primary process of highly effective dehydrogenation of the 1,3-cyclohexadiene ligand at the freshly formed ruthenium surface to form benzene was built in by the choice of the ligand. Further, but much less effective, was the dehydrogenation of benzene, which is presumed to be the main process for carbon contamination. Ruthenium films with only 3 mol.-% carbon content were deposited at a substrate temperature of 300°C and a carrier gas velocity of 12.8 cm s . In all cases the deposited films consist of polycrystalline metallic ruthenium with a low surface roughness.

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Dedicated to Professor Rudi van Eldik on the occasion of his 65th birthday(2), and [(2,3-dimethyl-1,3-butadiene)(toluene)Ru 0 ] (3) are prepared and tested as new metal-organic (MO) ruthenium precursor complexes with favorable deposition properties for the CVD of thin ruthenium films. X-ray diffraction (XRD) studies of single crystals of the complexes are characteristic for true Ru 0 p-complexes without molecular structure peculiarities or significant intermolecular interactions in the solid state, which can hinder undecomposed evaporation. Differential thermal analysis (DTA) and vapor pressure data qualify the compounds as almost ideal MOCVD precursors. Thin ruthenium films are deposited successfully on silicon wafers at substrate temperatures between 200 and 400 8C in a nitrogen gas atmosphere. X-ray photoelectron spectroscopy (XPS), fourpoint probe conductivity measurements, and atomic force microscopy (AFM) are used to characterize the films. All films consist of polycrystalline metallic ruthenium with a low surface roughness.

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Benzene)(2-methyl-1,3-cyclohexadiene)Ru( 0)] (1), [(1,3-cyclohexadiene)(toluene)Ru( 0)] (2), and [(methyl-cyclohexadiene)(toluene)Ru(0)] (3, mixture of isomers) have been prepared and tested as new metal organic ruthenium precursor complexes for chemical vapor deposition (MOCVD) with favorable properties. 1 is a low-melting precursor complex (mp ¼ 29 C) and the isomeric mixture 3 forms a liquid at room temperature. X-ray diffraction studies of single crystals of complexes 1 and 2 are characteristic for true Ru(0) p-complexes without molecular structure peculiarities or significant intermolecular interactions in the solid state, which could hinder undecomposed evaporation. Differential thermal analysis (DTA), differential scanning calorimetry (DSC) and vapor pressure data qualify the compounds as almost ideal MOCVD precursors. Thin ruthenium films have been deposited successfully on silicon wafers and substrate temperatures between 200 and 450 C in inert gas atmospheres. Film growth and properties were evaluated by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and four-point probe conductivity measurements. All films consist of polycrystalline metallic ruthenium with a low surface roughness.

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Tungsten -tungsten carbide thin films are deposited by metal-organic (MO)CVD on silica-coated silicon wafers using [cis-(1,3-butadiene) 2 W(CO) 2 ] and [cis-(1,3-cyclohexadiene) 2 W(CO) 2 ], respectively, as tunable precursor complexes. The compounds are prepared through photochemical ligand exchange reactions from [W(CO) 6 ] and fully characterized, including X-ray structure determination and detailed differential thermal analysis (DTA)/thermogravimetry (TG) investigations. Gas-phase diffusion coefficients and the vapor pressure of the compounds are calculated. The MOCVD experiments are performed in a vertical cold-wall reactor and the exhaust gas is analyzed by gas chromatography (GC). X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) measurements are utilized for film characterization. Consequences of the high oxophilicity of freshly formed tungsten surfaces, consecutive surface reactions of the complex ligands, film growth, and film properties are discussed. Inside the layers, tungsten carbide is identified as the main component.

Ruthenium thin films were deposed by MOCVD at moderate temperatures using [(1,5-cyclooctadiene)(toluene)Ru(0)] 1 and [(benzene)(1,3-cyclohexadiene)Ru(0)] 2 as precursor. The incorporation of carbon in the films could not be completely avoided, because of the high catalytic activity of Ru for C-H as well as C-C activated reactions. However, using suitable ligand combination and optimized deposition conditions it was possible to minimize the amount of carbon in the Ru films. The complex 2 provides better films due to strong reduction of the gaseous follow-up products, no C-C activated reactions and minimum carbon incorporation at optimized deposition temperature and gas velocity.