MOCVD of Thin Ruthenium Oxide Films: Properties and Growth Kinetics

Abstract

Conducting thin films of RuO 2 were grown on glass by metal±organic chemical vapor deposition (MOCVD) at substrate temperatures down to 623 K. Tris-trifluoroacetylacetonate-rutheniumIII (Ru(tfa) 3 ) served as the precursor. Film properties, such as resistivity, were improved by the addition of water to the reaction gas. The films were investigated by X-ray diffraction (XRD) and four-probe resistivity measurements. The growth mechanism was studied by in situ ellipsometry, and a model reaction mechanism is proposed. The electrochemical characterization by cyclic voltammetry revealed very small overpotentials for both hydrogen and oxygen evolution. The properties of the films, in particular the resistivity (r as low as 72 mW cm), are comparable to CVD and sputtered films deposited at much higher temperatures.

Surface and sub-surface thermal oxidation of thin ruthenium films

“…Previously, in situ spectroscopic ellipsometry (SE) was used to study growth of thin RuO 2 films during thermal oxidation of Ru. 24,25 However, it should be noted that extracting information from SE involves reconstruction of both optical constants and layered structure, a process which is often uniquely determined. We used in situ hard x-ray reflectivity measurements for monitoring thermal oxidation of Ru thin films.…”

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

“…However recently a large number of ruthenium complexes like ruthenium alkoxides, ruthenium alkyls, ruthenium amidinates, ruthenium diketonates, ruthenium carbonyls and others were exploited as precursor complexes. 1,53,[81][82][83][84] Thus, it is interesting to classify such complexes in terms of the nature of bonding of organic ligands formed by ruthenium and is described as follows: 2 were exploited as CVD precursors. 87 The molecular structures of some important ruthenium carbonyls are depicted in Fig.…”

“…A mixture of oxygen and water as carrier gas improved several thin lm properties like resistivity. The thin lm growth mechanism was studied by in situ ellipsometry 53 which showed that the nucleation occurred with lateral and vertical island growth in a rst step followed by a homogeneous lm growth preserving the surface roughness. A model reaction mechanism is proposed for growth kinetics: The reaction kinetics follows a rst-order Langmuir-Hinshelwood mechanism with growth rate dependent deposition parameters.…”

“…1. 53 From the growth kinetics of [Ru(tfa) 3 ], it is concluded that (1) [Ru(tfa) 3 ] provides most of the oxygen in the RuO 2 lm and the reaction is unimolecular.…”

Growth and thermal oxidation of Ru and ZrO2 thin films as oxidation protective layers

“…For instance, spectroscopic ellipsometry (SE) can be used for in situ monitoring thin film growth. 283,284 However, it should be noted that extracting information from SE involves reconstruction of both optical constants and layered structure, a process which is often non-uniquely determined. (Specular) X-ray reflectivity (XRR) is another example of technique that can be used for in situ monitoring thin film growth.…”