Diane Samélor

CVD of Pure Copper Films from Amidinate Precursor

Copper(I) amidinate [Cu(i-Pr-Me-AMD)]2 was investigated to produce copper films in conventional low pressure chemical vapor deposition (CVD) using hydrogen as reducing gas-reagent. Copper films were deposited on steel, silicon, and SiO2/Si substrates in the temperature range 200–350°C at a total pressure of 1333 Pa. The growth rate on steel follows the surface reaction between atomic hydrogen and the entire precursor molecule up to 240°C. A significant increase of the growth rate at temperatures higher than 300°C was attributed to thermal decomposition of the precursor molecule. It is shown that [Cu(i-Pr-Me-AMD)]2 meets the specifications for the metal organic chemical vapor deposition of Cu-based alloy coatings containing oxophilic elements such as aluminum.

Chemical Vapor Deposition of Iron, Iron Carbides, and Iron Nitride Films from Amidinate Precursors

Iron bis(N,N-diisopropylacetamidinate) [Fe2(µ-iPr-MeAMD)2(2-iPr-MeAMD)2] and iron bis(N,N-di-tert-butylacetamidinate) [Fe(tBu-MeAMD)2] were used as precursors for the metallorganic chemical vapor deposition (MOCVD) of iron-containing compounds including pure iron, iron carbides, Fe3C and Fe4C, and iron nitrides Fe4C. Their decomposition mechanism involves hydrogen migration followed by dissociation of the Fe–N bond and the release of free hydrogenated ligand (HL) and radicals. Surface intermediates are either released or decomposed on the surface providing Fe–N or Fe–C bonds. MOCVD experiments were run at 10 Torr, in the temperature ranges of 350–450°C with Fe2(µ−iPr-MeAMD)2(2-iPr-MeAMD)2 and 280–350°C with Fe(tBu-MeAMD)2. Films prepared from Fe2(µ−iPr-MeAMD)2(2-iPr-MeAMD)2 contain Fe, Fe3C, and Fe4C. Those prepared from Fe(tBu-MeAMD)2 contain Fe, Fe3C, and also Fe4C or Fe4N, depending on the temperature and hydrogen to precursor ratio (H/P) in the input gas. The room-temperature coercive field of films processed from Fe(tBu-MeAMD)2 is 3 times higher than that of the high temperature processed Fe4N films.

Phase Transformations of Metallorganic Chemical Vapor Deposition Processed Alumina Coatings Investigated by In Situ Deflection

Phase transformations of Al2O3 films, deposited by metallorganic chemical vapor deposition from aluminium tri-isopropoxide on AISI 301 stainless steel, were investigated using an original technique of deflection associated with X-ray diffraction and electron microscopy. The samples were first oxidized at 1123 K in air to obtain a 0.9 m thick Cr2O3 protective oxide film on one side of the samples. Then, 1 m thick amorphous Al2O3 films were deposited on the opposite side at 823 K and 2 kPa. The deflection of such dissymmetrical samples was recorded during anisothermal treatments, consisting in slow heating to 1173 K in Ar atmosphere. The coefficient of thermal expansion of both the Cr2O3 and the amorphous Al2O3 films was determined to be 7 10-6 K-1 and 14.7 10-6 K-1, respectively. Crystallization kinetics of amorphous to mainly ~–Al2O3 become significant at temperatures equal or greater than 983 K. Transformation of metastable Al2O3 to –Al2O3 is initiated below 1173 K. It is demonstrated that deflection is a powerful tool for investigating the behavior of thin films deposited on a substrate and especially to reveal transformations occurring in these films during heat-treatments.

Electrochemical Behavior of Chemical Vapor Deposited Protective Aluminum Oxide Coatings on Ti6242 Titanium Alloy

The electrochemical behavior at room temperature in a neutral sodium chloride aqueous solution of four types of metallorganic chemical vapor deposited aluminum oxide coatings on commercial Ti6242 titanium alloy was investigated. Polarization and electrochemical impedance curves revealed that porosity free, amorphous alumina coatings provide a two order of magnitude improvement of the corrosion resistance with regard to the bare alloy. Crystallized alumina as well as amorphous AlO(OH) only slightly improve the corrosion resistance of Ti6242. It was demonstrated that metallorganic chemical vapor deposition processed amorphous alumina is a highly promising solution to the protection of titanium alloys against corrosion in salt environments.

Low Temperature MOCVD-Processed Alumina Coatings

We first present a Review about the preparation of alumina as thin films by the technique of MOCVD at low temperature (550°C and below). Then we present our results about thin films prepared by the low pressure MOCVD technique, using aluminium tri-isopropoxide as a source, and characterized by elemental analysis (EMPA, EDS, ERDA, RBS), FTIR, XRD and TGA. The films were grown in a horizontal, hot-wall reactor, with N2 as a carrier gas either pure or added with water vapour. The deposition temperature was varied in the range 350-550°C. The films are amorphous. Those prepared at 350°C without water added in the gas phase have a formula close to AlOOH. Those deposited above 415°C are made of pure alumina Al2O3. When water is added in the gas phase, the films are pure alumina whatever the deposition temperature.

Mechanical and Surface Properties of Chemical Vapor Deposited Protective Aluminium Oxide Films on TA6V Alloy

Mechanical, barrier and surface properties of aluminium oxide films were investigated by nanoindentation, microscratch and micro tensile tests, by isothermal oxidation and voltammetry, and by contact angle measurement. The films were grown on TA6V substrates by a low pressure MOCVD process from aluminium tri-isopropoxide. Modelling of local gas flow, gas concentration and deposition rate profiles was performed using the CFD code Fluent on the basis of an apparent kinetic law. Films grown at 350 °C are amorphous AlO(OH), the one at 480 °C is amorphous Al2O3 and the one at 700 °C is nanocrystalline -Al2O3. Scratch tests and micro tensile tests resulted in adhesive failure on the two films grown at low temperature whereas cohesive failure was observed for the high temperature growth. Sample processed at 350 °C presents significantly lower oxidation kinetics in dry air than the bare substrate. Contact angle changes approximately from 100 to 50 degrees for films processed at 350-480 °C and 700 °C, respectively. Concerning the electrochemical behavior in NaCl environment, polarization curves revealed that amorphous alumina coatings improved the corrosion resistance by comparison with the others oxide films. These consolidated results reveal promising combination of properties for the films grown at different temperatures with regard to the targeted applications.

Iron amidinates as precursors for the MOCVD of iron-containing thin films

Alain N. Gleizes, Vladislav Krisyuk, Lyacine Aloui, Asiya Turgambaeva, Bartosz Sarapata, Nathalie Prud’Homme, Francois Senocq, Diane Samelor, Anna Zielinska-Lipiec, Frederic Dumestre and Constantin Vahlas 1 CIRIMAT, ENSIACET, 118 Route de Narbonne, 31077 Toulouse cedex 4, France. E-mail: constantin.vahlas@ensiacet.fr, phone: +33 562 885 670, fax: +33 562 885 600 2 Nikolaev Institute of Inorganic Chemistry SB RAS ; Ave. Lavrentiev, 3, Novosibirsk, 630090, Russia. E-mail: vladislav.krisyuk@ensiacet.fr 3 AGH University of Science and Technology (AGHUST), Al. Mickiewicza 30, PL-30 059 Krakow, Poland. E-mail : sarapata@agh.edu.pl 4 NanoMePS ; Departement de Genie Physique, INSA, 135 Avenue de Rangueil, 31077 Toulouse Cedex 4, France. E-mail : contact@nanomeps.fr

Amorphous alumina coatings on glass bottles using direct liquid injection MOCVD for packaging applications

In the field of packaging, coatings are commonly applied on containers to avoid interactions between them and their content. For glass bottles, application of a thin film prevents interactions with the phase in contact and consequently the alteration of surface properties of the latter. In this article, we propose an innovative way to apply amorphous alumina coatings on glass bottles by metalorganic chemical vapor deposition from aluminum tri-isopropoxide. A numerical model, using the Computational Fluid Dynamics code FLUENT, has been developed to calculate local profiles of gas flow, temperature, concentration and deposition rates into the reactor. The sub-micrometric alumina films have been deposited at reduced pressure between 480°C and 670°C. Uniform thickness profiles have been determined on cross sections over the length of the bottle and have been successfully simulated. Strongly improved hydrolytic resistance with regard to the uncoated bottles reveals the excellent performance of the films.

Protective Alumina Coatings by Low Temperature Metalorganic Chemical Vapour Deposition

Alumina thin films were processed by MOCVD from aluminium tri-iso-propoxide, with N2 as a carrier gas, occasional addition of water in the gas phase, deposition temperature in the range 350-700°C, total pressure 0.67 kPa (2 kPa when water was used). The films do not diffract Xray when prepared below 700°C. At 700°C, they start to crystallize as γ-alumina. EDS, EPMA, ERDA, RBS, FTIR and TGA revealed that films prepared in the range 350-415°C, without water in the gas phase, have an overall composition Al2O3-x(OH)2x, with x tending to 0 with increasing temperature. Al2O3 is obtained above 415°C. When water is added in the gas phase, the film composition is Al2O3, even below 415°C. Coatings deposited in these conditions show promising protection properties.

Residual Stress Mechanisms in Aluminum Oxide Films Grown by MOCVD

Residual stresses in amorphous aluminium oxide films were investigated with in situ wafer curvature measurements. The films were deposited from aluminium tri-isopropoxide, on sapphire substrates. Large tensile stresses of 1-2 GPa occurred during growth. These values are well above the fracture stress in bulk materials, but they are sustainable in thin film form. Subsequent heat treatment of these films produced additional tensile stress, even at low temperatures prior to crystallization. The mechanisms responsible for all of these stress contributions are discussed. The variety of operative mechanisms at low to moderate temperatures in these amorphous films suggests that different processing routes can be used to engineer significant differences in the final stress state of these materials.