Influence of Water on Chemical Vapor Deposition of Ni and Co thin films from ethanol solutions of acetylacetonate precursors

Abstract

In chemical vapor deposition experiments with pulsed spray evaporation (PSE-CVD) of liquid solutions of Ni and Co acetylacetonate in ethanol as precursors, the influence of water in the feedstock on the composition and growth kinetics of deposited Ni and Co metal films was systematically studied. Varying the water concentration in the precursor solutions, beneficial as well as detrimental effects of water on the metal film growth, strongly depending on the concentration of water and the β-diketonate in the precursor, were identified. For 2.5 mM Ni(acac)2 precursor solutions, addition of 0.5 vol% water improves growth of a metallic Ni film and reduces carbon contamination, while addition of 1.0 vol% water and more leads to significant oxidation of deposited Ni. By tuning the concentration of both, Ni(acac)2 and water in the precursor solution, the fraction of Ni metal and Ni oxide in the film or the film morphology can be adjusted. In the case of Co(acac)2, even smallest amounts of water promote complete oxidation of the deposited film. All deposited films were analyzed with respect to chemical composition quasi in situ by XPS, their morphology was evaluated after deposition by SEM.

Thermal Chemistry of Metal Organic Compounds Adsorbed on Oxide Surfaces

“…Another family of metal organics with bridge-bonded ligands used in chemical film deposition applications is diketonates. The most common ligands used in this case are the simplest acetylacetonate (acac) − and hexafluoroacetylacetonate (hfac) − moieties, but other diketonates with larger side chains are also known. ,− In many of the reported uses of these compounds the final target has been a metal oxide film, but some examples are also available for the growth of metallic films with these precursors, especially with late transition metals. ,− Although the studies available to date suggest that diketonates may be less reactive on surfaces than amidinates, they are still prone to fragmentation upon thermal activation.…”

Editors' Choice—Review—Cobalt Thin Films: Trends in Processing Technologies and Emerging Applications

“…A number of studies have also examined the role of additives in precursor decomposition mechanisms and the resulting Co film morphology and properties. For instance, Premkumar et al 8 compared the effects of isopropanol and n-propanol in MOCVD Co from Co(acac) 2 (Co-201), determining that the former yielded Co 2 C at substrate temperatures in the range of 205-230 • C, while the latter produced metallic Co at temperatures above 250 • C. Weiss et al 31 examined the addition of water to a solution of Co(acac) 2 (Co-201) in ethanol to investigate the effects of humidity on precursor stability and MOCVD performance, concluding that water inclusion at any concentration led to the growth of a Co oxide phase.…”

Enhanced property of thin cuprous oxide film prepared through green synthetic route

“…Particularly, the band gap characteristic, one of the important properties involving absorption intensity of sunlight for semiconductors, can be tuned via PSE-CVD [42][43][44][45]. Recently, Baeumer et al have investigated the effect of water on the thin film composition and growth kinetics, and found that the water has a beneficial effect and strongly depending on the concentration of water in the feedstock [46]. In additi-on, in our previous work, the involvement of water in the preparation provided a very good effect on the catalytic performance of CO [47].…”