M. Aslam Siddiqi

Thermal Stability and Sublimation Pressures of Some Ruthenocene Compounds

We set out to study the use of a series of ruthenocenes as possible and promising sources for ruthenium and/or ruthenium oxide film formation.The thermal stability of a series of ruthenocenes, including (η5-C5H4R)(η5-C5H4R´)Ru (1), R = R´ = H (3), R = H, R´ = CH2NMe2 (5), R = H, R´= C(O)Me (6), R = R´ = C(O)Me (7), R = H, R´ = C(O)(CH2)3CO2H (8), R = H, R´ = C(O)(CH2)2CO2H (9), R = H, R´ = C(O)(CH2)3CO2Me (10), R = H, R´= C(O)(CH2)2CO2Me (11), R = R´ = SiMe3), (η5-C4H3O-2,4-Me2)2Ru (2), and (η5-C5H5-2,4-Me2)2Ru (4) was studied by thermogravimetry. From these studies, it could be concluded that 1–4, 6 and 9–11 are the most thermally stable molecules. The sublimation pressure of these sandwich compounds was measured using a Knudsen cell. Among these, the compound 11 shows the highest vapor pressure.

Methylated [(arene)(1,3-cyclohexadiene)Ru(0)] complexes as low-melting MOCVD precursor complexes with a controlled follow-up chemistry of the ligands

[(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 = 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) π-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.

Ruthenium complexes as precursors for chemical vapor-deposition (CVD)

Ruthenium and its compounds are often used as thin films and can be deposited by chemical vapor deposition. The quality of the films strongly depends on the inorganic precursors, their evaporation behaviour and thermochemistry. This is an area where different aspects of inorganic chemistry and chemical engineering must fit together to provide good thin films. It was noticed that providing firsthand information in one place especially for a learner of this area of research, and collection of reports on different types of ruthenium complexes as CVD precursors would be timely. Thus, in this review a birds eye view of ruthenium complexes suitable for CVD technology, together with the presentation of different precursors, their synthesis, evaporation, decomposition and film formation is presented. A brief summary of the CVD technique is also presented with future-design, synthesis and usefulness of CVD precursors.