EP2049703A1

EP2049703A1 - One-step method for applying a metal layer onto a substrate

Info

Publication number: EP2049703A1
Application number: EP07787205A
Authority: EP
Inventors: Katharina KOHSE-HÖINGHAUS; Naoufal Bahlawane; Antony Premkumar
Original assignee: Universitaet Bielefeld
Current assignee: Universitaet Bielefeld
Priority date: 2006-07-14
Filing date: 2007-07-09
Publication date: 2009-04-22
Also published as: DE102006033037A1; WO2008006785A1

Abstract

The invention relates to a one-step method for applying at least one metal layer onto a substrate by means of a gas phase deposition method. A substrate is coated with a metal layer in that a metal from a metal-containing precursor compound is precipitated from a gas phase onto the substrate, the metal-containing precursor compound is dissolved in a solvent, an organic reactant is added, and the metal-containing precursor compound and the organic reactant are converted into the gas phase, the metal of the metal-containing precursor compound is released by means of the organic reactant and the released metal is deposited onto the substrate.

Description

University of Bielefeld Universitätsstraße 25, 33615 Bielefeld, Germany

One step process for applying a metal layer to a substrate

The invention relates to a one-step process for applying metal layers to a substrate by a chemical vapor deposition method.

Gas phase chemical vapor deposition (CVD) methods and atomic layer deposition (ALD) techniques are widely used in the art to form layers of metal, metal oxide, metal nitride , Metal carbide and the like.

CVD processes are understood as meaning coating processes for producing thin layers, in particular of metal or metal oxide, on substrates in which the coating material is converted into the gas phase, for example by chemical methods, in order subsequently to be deposited on a substrate. The metals to be deposited or the metallic components of the layer material are used in the form of a "precursor compound" or "precursor". This precursor compound reacts to supply energy to the Substratoberfiäche to form, for example, a metal or metal oxide layer.

A "precursor compound" or "precursor" is understood to mean compounds which are preferably vaporisable and contain the material-constituent chemical constituents of the layer to be formed and thus serve as transport means for the metallic components of the layer material. Frequently used precursor compounds are organometallic and organometallic compounds. Organometallic compounds are usually very toxic and extremely sensitive to oxygen or air and moisture, while organometallic compounds such as diketonates are more stable, but require the addition of reducing agents such as hydrogen for the deposition of metal layers. As the reducing agent, hydrogen is usually used when it is desired to deposit in a reducing atmosphere. Hydrogen is known to be easily flammable and requires a correspondingly high security effort.

For example, document US 2003/0185981 A1 discloses depositing metal oxide layers using organometallic precursor compounds and alcohol as the reaction gas. However, a deposition of pure metal layers is not disclosed. It is rather known in the prior art that the resulting metal oxide layers must still be reduced to metals by reducing agents such as hydrogen in a further process step.

The methods known in the prior art for the chemical deposition of metal layers from the gas phase thus require either extremely oxygen- and moisture-sensitive organometallic precursor compounds or the use of reducing agents such as hydrogen. In particular, the deposition of metal layers of non- or semi-precious metals is usually carried out using inorganic reducing agents such as hydrogen.

The present invention was therefore based on the object to provide a method which overcomes at least one of the aforementioned disadvantages of the prior art. In particular, the present invention was based on the object to provide a method that allows the deposition of a metal layer, without having to use hydrogen as an additional reducing agent. This object is achieved by a one-step process for applying at least one metal layer to a substrate by a gas phase chemical vapor deposition method wherein a substrate is coated with a metal layer by depositing a metal-containing precursor compound from a gaseous phase on the substrate in which the metal-containing precursor compound is dissolved in a solvent, an organic reactant is introduced, and the metal-containing precursor compound and the organic reactant are gasified to release the metal from the metal-containing precursor compound via the organic reactant, thereby depositing the released metal onto the substrate becomes.

Another object of the present invention relates to a substrate coated with a metal layer applied by the method according to the invention.

Further advantageous embodiments of the invention will become apparent from the dependent claims.

For the purposes of the present invention, the term "reactant" is to be understood as meaning a starting material for a chemical reaction with the metal-containing precursor compound.

It has surprisingly been found that the process according to the invention makes it possible to apply metal layers, in particular from organometallic precursor compounds which are dissolved in a preferably organic solvent, in a one-step process, the metal being released from the metal-containing precursor compound by means of the organic reactant. Of particular advantage here is that no inorganic reducing agents such as hydrogen must be used.

In particular, it was surprisingly found that a deposition of non-noble metals or semi-precious metals without using inorganic reducing agents how hydrogen is allowed. This is particularly surprising, since a deposition of non-noble metals or semi-precious metals without the use of inorganic reducing agents is not yet known. In particular, surprisingly, deposition of iron layers without inorganic reducing agents could be achieved. This is particularly surprising, since a deposition of iron from organometallic precursor compounds such as Eisenacetylaceonat now accessible by CVD method.

A great advantage of the method according to the invention can be provided by the fact that the method according to the invention makes it possible to deposit metal layers on metal oxide substrates, which are slightly reduced, for example by strongly reducing reagents such as hydrogen. This provides a particular advantage of the method according to the invention which is suitable for coating sensitive substrates such as metal oxides with metal layers. Deposition of metal layers by conventional methods provides for reduction with hydrogen, which would also reduce a metal oxide substrate to be coated. The process according to the invention, which preferably uses mild or clearer milder reactants and / or reducing agents than hydrogen, allows sensitive substrates such as metal oxide substrates to be coated with metal layers.

By means of the deposition according to the invention, deposition without incubation time can advantageously be made available. It is of very particular advantage that the deposition of metal layers according to the method of the invention can proceed without incubation time and, for example, enables the deposition of very thin metal layers. Further advantages of the deposition of metal layers according to the method according to the invention are that, without incubation time, it is possible to deposit layers with significantly improved smoothness. In particular, the deposited layers may have a lower roughness. The organic reactant and the metal-containing precursor compound may be fed together or separately to the reaction chamber. For example, the organic reactant and the metal-containing precursor compound may be supplied to the reaction chamber together or alternately. The organic reactant can be supplied via a carrier gas. Furthermore, the metal-containing precursor compound can be supplied via a carrier gas. The organic reactant and the metal-containing precursor compound may be supplied together via a carrier gas, or separately, for example, alternately, using one or more different carrier gases. The partial pressure of the organic reactant and the metal-containing precursor compound can be controlled, for example, by controlling the evaporation temperature.

Preferably, the organic reactant and the metal-containing precursor compound form a mixture, more preferably the metal-containing precursor compound is dissolved in the organic reactant.

It is a further advantage of the process of the invention that the dissolution of the metal-containing precursor compound in a solvent enables the use of metal-containing precursor compounds having limited volatilization capability.

Suitable organic reactants have at least one function of an organic compound selected from the group consisting of alcohol (s), aldehyde (s), amine (s), ether and / or thiol (s), preferably a functional group selected from the group comprising OH , NH ₂ , NH, and / or SH groups. The organic reactant may also have several identical and / or several different functions, for example in the case of polyols or ethanolamine. In preferred embodiments of the invention Method is the organic reactant selected from the group comprising alcohol (s), aldehyde (s), amine (s), ethers, thiol (s) and / or mixtures thereof. Here, alcohol (s) are particularly preferred.

Particularly suitable organic reactants are alcohols. An advantage of the use of alcohols is, in particular, that alcohols can be handled easily and without increased safety precautions. Suitable alcohols may be selected from the group comprising primary, secondary and / or tertiary alcohols. Suitable alcohols preferably have the formula R-OH, where R is a suitable organic radical from the group consisting of alkyl, alkenyl, cycloalkyl, aryl and aralkyl, preferably R is C 1 -C 10 -alkyl. It is possible to use in particular alcohols which are liquid at room temperature and have an organic radical having up to 10 carbon atoms. Also suitable are aromatic alcohols. Preferably, the alcohol is selected from the group comprising alcohols having an organic radical having 1 to 6 carbon atoms, preferably R is Ci-C _ό -alkyl. Preference is given to using short-chain aliphatic alcohols having 1 to 5 carbon atoms, R is preferably C 1 -C 5 -alkyl.

Particularly preferred alcohols are volatilizable alcohols. Preferred alcohols are selected from the group comprising methanol, ethanol, isopropanol, n-propanol, n-butanol, tert-butanol, phenol and / or mixtures thereof. Particularly preferred alcohols are selected from the group comprising methanol, ethanol, n-propanol and / or isopropanol.

An advantage of using alcohols selected from the group comprising methanol, ethanol, n-propanol and / or iso-propanol is that they have in particular suitable dissolution properties for metal-containing precursor compounds, in particular organometallic precursor compounds. Particularly preferably usable alcohols are methanol and ethanol, in particular ethanol. Without wishing to be bound by any particular theory, it is believed that the advantageous properties of the process of the invention are due to a reaction of the metal-containing precursor compound with the organic reactant, which can induce reduction of the metal.

A surprising advantage, in particular when using alcohols as organic reactant and / or solvent, in particular for organometallic precursor compounds, is that pure metal can be deposited. Deposited metal layers are preferably not or only to a very small extent contaminated, for example, with oxygen or carbon, metal oxide, or metal carbide or similar by-products, often caused by organic solvents and / or ligands of the organometallic precursor compounds. In particular, metal layers can be deposited freely or almost free of impurities.

The solvent is preferably an organic solvent. Suitable solvents are, for example, selected from the group comprising alcohol (s), aldehyde (s), amine (s), ether and / or thiol (s), preferably alcohols selected from the group comprising methanol, ethanol, isopropanol, n-propanol, n-butanol, tert-butanol, phenol and / or mixtures thereof. Particularly preferred alcohols are selected from the group comprising methanol, ethanol, n-propanol and / or iso-propanol.

The solvent may be the same or different from the organic reactant. Preferably, the metal-containing precursor compound is dissolved in the organic reactant. This is particularly advantageous in the use of metal-containing precursor compounds with low volatilization. It is particularly preferable that the organic reactant is usable as an organic solvent for the metal-containing precursor compound.

In particularly preferred embodiments, a metal is deposited from a metal-containing precursor compound from a gaseous phase on the substrate, dissolving the metal-containing precursor compound in an organic reactant, converting this mixture to the gaseous phase, releasing the metal from the metal-containing precursor compound by means of the organic reactant with the released metal being deposited on the substrate.

In a preferred embodiment of the process according to the invention, the organic reactant is an organic reducing agent.

In the context of this invention, an "organic reducing agent" is to be understood as meaning organic compounds, in particular organic reactants, whose reaction with the metal center of the metal-containing precursor compound can induce a reduction of the metal.

In another embodiment of the process of the invention, the process is a one-step process for depositing at least one metal layer on a substrate by a gas phase chemical vapor deposition process, coating a substrate with a metal layer by forming a metal from a metal containing precursor compound Depositing gas phase on the substrate, dissolving the metal-containing precursor compound in an organic reducing agent, converting this mixture into the gaseous phase, releasing the metal from the metal-containing precursor compound by means of the organic reducing agent, thereby depositing the released metal onto the substrate. The term "dissolving" in the context of the present invention means that the metal-containing precursor compound is dissolved, emulsified or suspended.

The organic reducing agent is preferably a liquid. The term "liquid" in the context of the present invention means that the organic reducing agent in a temperature range of 10 ⁰ C to 100 ⁰ C, preferably at room temperature, ie in a temperature range of 18 ° C to 25 ⁰ C, liquid. It can also be provided that the organic reducing agent is verfiüssigbar.

This allows a precursor compound in the organic reducing agent to be dissolved, emulsified or suspended. Furthermore, this makes it possible that the organic reducing agent is vaporizable under controlled conditions.

Preferably, the organic reducing agent is an organic liquid. The organic reducing agent may advantageously act as a reducing agent and as a solvent. Advantageously, the solvent is an organic reducing liquid. Preferably, a useful solvent is a solvent.

Preferably, to release the metal from the metal-containing precursor compound in addition to the inventively usable organic reducing agent, which formulation also includes mixtures, no further reducing agents are used. According to a preferred embodiment, in particular no inorganic reducing agents are used.

Surprisingly, it has been found that the process according to the invention makes it possible to apply metal layers, in particular from organometallic precursor compounds which are dissolved in an organic reducing agent, preferably an organic reducing liquid, in a one-step process, in which only organic compounds are used Reducing agent can be used. Thus, according to the present invention, no inorganic reducing agents such as hydrogen are used.

A great advantage of the method according to the invention can be provided by the fact that the method according to the invention makes it possible to deposit metal layers on metal oxide substrates, which are slightly reduced, for example by strongly reducing reagents such as hydrogen. This provides a particular advantage of the method according to the invention which is suitable for coating sensitive oxidic substrates such as metal oxides with metal layers. Deposition of metal layers by conventional methods provides for reduction with hydrogen, which would also reduce a metal oxide substrate to be coated. The process according to the invention, which preferably uses mild or clearer milder reducing agents than hydrogen, allows sensitive substrates such as metal oxide substrates to be coated with metal layers.

By deposition, wherein the organic reducing agent forms the sole reducing agent of the deposition process and the precursor compound is dissolved in the organic reducing agent, deposition without incubation time can advantageously be provided. It is of very particular advantage that the deposition of metal layers according to the method of the invention can proceed without incubation time and, for example, enables the deposition of very thin metal layers. Further advantages of the deposition of metal layers according to the method according to the invention are that, without incubation time, it is possible to deposit layers with significantly improved smoothness. In particular, the deposited layers may have a lower roughness.

This allows control of the deposition process, which in known deposition methods for metals due to the incubation time, in the range of several Minutes to hours depending on the substrate to be coated can not be achieved.

Preferably, the usable organic reducing agent is a liquid organic solvent. The liquid organic solvent preferably has at least one function of an organic compound selected from the group comprising alcohol (s), aldehyde (s), amine (s), ether and / or thiol (s), preferably a functional group selected from the group comprising OH, NH ₂ , NH, and / or SH groups. The organic reducing agent or the reducing liquid may also have a plurality of identical and / or a plurality of different functions, for example in the case of polyols or ethanolamine.

In preferred embodiments of the process according to the invention, the organic reducing agent is selected from the group comprising alcohol (s), aldehyde (s), amine (s), ether, thiol (s) and / or mixtures thereof. Here, alcohol (s) are particularly preferred. An advantage of using organic reducing agents selected from the group consisting of alcohol (s), aldehyde (s), amine (s), ethers, thiol (s) and / or mixtures thereof is that they can provide suitable reduction properties. A particular advantage of using organic reducing agents is that their reaction with the metal center of the metal-containing precursor compound can induce reduction of the metal.

Particularly suitable organic reducing agents with suitable reducing properties are alcohols. An advantage of the use of alcohols is, in particular, that alcohols can be handled easily and without increased safety precautions. Suitable alcohols may be selected from the group comprising primary, secondary and / or tertiary alcohols. Suitable alcohols preferably have the formula R-OH, wherein R is a suitable organic radical from the group alkyl, alkenyl, cycloalkyl, aryl and Aralkyl, preferably R is Ci-Cio-alkyl. It is possible to use in particular alcohols which are liquid at room temperature and have an organic radical having up to 10 carbon atoms. Also suitable are aromatic alcohols. Preferably, the alcohol is selected from the group comprising alcohols having an organic radical having 1 to 6 carbon atoms, preferably R is Ci-C _ό -alkyl. Preference is given to using short-chain aliphatic alcohols having 1 to 5 carbon atoms, preference being given to R C1-C5-alkyl. Particularly preferred alcohols are volatilizable alcohols.

Preferred alcohols are selected from the group comprising methanol, ethanol, isopropanol, n-propanol, n-butanol, tert-butanol, phenol and / or mixtures thereof. Particularly preferred alcohols are selected from the group comprising methanol, ethanol, n-propanol and / or iso-propanol.

An advantage of using alcohols selected from the group comprising methanol, ethanol, n-propanol and / or iso-propanol is that they have in particular suitable dissolution properties for metal-containing precursor compounds, in particular organometallic precursor compounds. Particularly preferably used alcohols are methanol and ethanol, in particular ethanol, which can provide particularly advantageous properties in terms of a combination of Löseeigenschaft, reduction effect and handling and costs.

A major advantage of using alcohols, especially ethanol or methanol as a reducing agent, is that they are easy to handle and do not require increased safety precautions such as the highly flammable and explosive gas hydrogen. In addition, especially ethanol or methanol are particularly inexpensive. Another significant advantage of using alcohols, especially ethanol or methanol, is that they are almost completely recoverable, for example, by evaporating the alcohol after it has been evaporated a cold trap can be condensed and can be available for reuse. Another advantage of the method according to the invention is therefore likewise that the method is more environmentally friendly in comparison with known methods.

"Metals" in the sense of the present invention are pure metals, it being possible for at most small amounts of impurities to be present, not metal oxides.

Surprisingly, it has been found that in the deposition process according to the invention undesired incorporation of carbon or oxygen into the resulting metal layer does not take place or only to a very small extent. This represents a major advantage over a coating in a conventional hydrogen atmosphere.

A surprising advantage in the use of alcohols as solvents, in particular for organometallic precursor compounds and at the same time as the sole reducing agent in the deposition of the metal layers by means of chemical vapor deposition is that pure metal can be deposited. Deposited metal layers are preferably not or only to a very small extent contaminated, for example, with oxygen or carbon, metal oxide, or metal carbide or similar by-products, often caused by organic solvents and / or ligands of the organometallic precursor compounds.

In particular, metal layers can be deposited freely or almost free of impurities. Thus, it could be stated that deposited metal layers had a conductivity which hardly deviated from that of the pure metals. Thus, it was found that, for example, for a deposition of silver, nickel and copper layers, a deviation was only in the range of 0.1 μΩ cm to 3 μΩ cm compared to that of the pure metals. Also suitable as solvents are nitrogen compounds, in particular with functional NH ₂ and / or NH groups, for example primary and secondary amines, aromatic amines, or hydrazine (N ₂ H ₄ ). Useful amines are preferably selected from the group comprising primary and / or secondary mono- and dialkylamines of the formulas R ¹ NH ₂ and / or R ¹ R ² NH, wherein R ¹ and R ² can be selected independently from the group comprising a suitable organic radical from the group alkyl, alkenyl, cycloalkyl, aminoalkyl, monoalkylaminoalkyl, dialkylaminoalkyl, aryl and aralkyl. R ¹ and R ² may together with the nitrogen atom form a 3- to 7-membered heterocycle which may optionally have one or more double bonds and optionally one further heteroatom from the group N, O and S. Preferably, R ^{1 is} C ₂ - to C ₆ -alkyl or R ¹ and R ² are independently C ₂ - to C _ό -alkyl.

Preferred amines are selected from the group comprising diethylamine, n-propylamine, iso-propylamine, n-butylamine, tert-butylamine and / or isobutylamine.

A substrate to be coated can be placed in a coating chamber or reactor.

The precursor compounds are preferably passed over the substrate by means of a carrier gas. Precursor compounds or precursors which are suitable according to the invention are metal-containing compounds, preferably organometallic compounds.

Suitable are solid, gaseous and / or liquid metal-containing precursor compounds and / or colloidal-disperse solutions.

Preferred metal-containing precursor compounds are selected from the group comprising ionic or inorganic metal-containing compounds such as Halogen compounds, nitrates, carbonates and sulfides, organometallic and / or organometallic compounds, or mixtures thereof.

Preferred gaseous or soluble halogen compounds are in particular selected from the group comprising fluorides, chlorides, bromides and / or iodides. Further preferred ionic or inorganic metal-containing precursor compounds are metal nitrates.

Preferred organometallic precursor compounds are high valence organometallic compounds, for example, cyclopentadienyl compounds.

A further advantage of the method according to the invention is that any metal-containing precursor compound is usable for the deposition of metal layers, in particular also organometallic precursor compounds are less sensitive to air, light and moisture and expensive than organometallic precursor compounds, wherein in the process according to the invention no further Reducing agents such as hydrogen must be used.

Preferred organometallic precursor compounds are selected from the group consisting of metal alkoxides, metal carbonyls, metal dithiocarbamates, metal borides, metal amidinates, metal carboxylates, metal dithiophosphates and / or metal diketonate. Particularly preferred organometallic precursor compounds are metal β-diketonates, in particular selected from the group comprising metal acetylacetonates, metal hexafluoroacetylacetonates and / or metal triisopropoxides.

Very particularly preferred metal-containing, in particular organometallic, precursor compounds are selected from the group comprising metal acetylacetonates and / or metal hexafluoroacetylacetonates, in particular nickel (II) acetylacetonate, copper (II) acetylacetonate, cobalt (II) acetylacetonate, silver nitrates, and / or (hfac) Ag ( l, 5 COD), where COD is cyclooctadiene and hfac is hexafluoroacetylacetonate. A most preferred organometallic precursor compounds is ferrous acetylacetonate.

The metal of the metal-containing precursor compounds is preferably selected from the group comprising transition metals of the subgroups of the Periodic Table. Preferred transition metals are selected from the group consisting of Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd and / or Hg. Particularly preferred metals of the metal-containing precursor compounds are selected from the group consisting of Fe, Ce, Rh, Ru, Co, Ni, Pd, Pt, Cu, Ag and / or Au, most preferably selected from the group comprising Ni, Cu, Co and / or Ag.

It is a particular advantage of the method according to the invention that the deposition of metal layers of non-ferrous or semi-precious metals without the use of inorganic reducing agents such as hydrogen is made possible. It is of very particular advantage here that the deposition of metal layers of very base metals such as iron without the use of inorganic reducing agents such as hydrogen is made possible.

The metal of the metal-containing precursor compounds is preferably selected from the group consisting of Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Os, Ni, Pd, Pt, Ag, Au, and / or Cd, preferably selected from the group consisting of Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Os , Ni, and / or Cd. Very particularly preferred metals of the metal-containing precursor compounds are selected from the group comprising Ni, Fe, Co and / or Ag.

In preferred embodiments, the metal of the metal-containing precursor compounds is a semi-precious metal, especially Ag. In further preferred embodiments, the metal of the metal-containing precursor compounds is a non-noble metal, in particular selected from the group comprising Mo, Fe, Co, Cr, Ni and / or W.

In still further preferred embodiments, the metal of the metal-containing precursor compounds is a very non-noble metal, in particular selected from the group comprising Ti and / or Fe.

It is a further advantage that the process according to the invention permits deposition of iron, for example starting from iron (II) acetylacetonate, using ethanol as organic reactant by means of thermal CVD processes.

In very preferred embodiments, the metal of the metal-containing precursor compounds is selected from the group comprising Ni, Fe, Co and / or Ag, most preferred metals of the metal-containing precursor compounds are selected from the group comprising Ni, Fe and / or Co.

In also preferred embodiments, the metal of the metal-containing precursor compounds is not selected from the group comprising Ru, Rh, Ir and / or Cu.

The precursor compounds are dissolved, emulsified or suspended in the organic reducing agent, especially an alcohol such as ethanol or methanol.

Preferred combinations of an organometallic precursor compound according to the invention and an organic reducing agent, preferably a reducing liquid, are metal β-diketonates dissolved in alcohol. Particularly preferred combinations are metal acetylacetonates such as nickel (II) acetylacetonate copper (II) acetylacetonate, Cobalt (II) acetylacetonate, silver nitrate, and / or (hfac) Ag (1.5 COD) dissolved in ethanol or methanol.

The concentration of the dissolved metal-containing precursor compound can vary widely, for example in a range of> 1 nM to 1 <M. The concentration of the dissolved metal-containing precursor compound can only be limited by the saturation of the individual precursor compound in the organic reducing agent, preferably the reducing liquid , especially an alcohol. Preferably, the metal-containing precursor compound is dissolved at a concentration in the range of> 0.1 mM to <50 mM, preferably in the range of> 1 mM to <50 mM, preferably in the range of> 5 mM to <25 mM, in an organic reducing agent , preferably in the reducing liquid, especially in ethanol or methanol.

The precursor compounds are preferably passed into the reactor by means of an inert carrier gas. Preferred carrier gases are inert gases, for example nitrogen or a noble gas, preferably argon.

The precursor compounds can be evaporated or sublimed by suitable methods. The precursor compounds can be heated, for example, to an evaporation temperature in the range from> 300 K to <600 K, preferably in the range from> 350 K to <500 K, particularly preferably in the range from> 380 K to <450 K.

The process of the invention can provide the further advantage that a lower evaporation temperature of the precursor compounds is needed. In particular, a use of alcohols such as ethanol as an organic reactant, for example, in Nicke lacetylacetat lead to a reduction in the evaporation temperature of up to 100 ⁰ C. Before the precursor compound is introduced into the coating chamber, the precursor compound may be supplied to, for example, a nebulizer or an evaporator / gasifier to be converted to the gaseous form. The carrier gas can likewise be fed into the evaporation apparatus, and the mixture thus produced comprising gaseous precursor compound and carrier gas can optionally be supplied to the substrate in a coating chamber.

The precursor compounds can be supplied in gaseous form to the substrate, or in liquid form, for example by pulsed or direct liquid injection or as an aerosol, preferably by means of a carrier gas, are fed to the substrate and / or introduced into a coating chamber. Preferably, the precursor compound is in liquid form, for example as an aerosol.

For example, in conventional thermal CVD or Direct Liquid Injection Metal Organic Chemical Vapor Deposition (DLI-MOCVD) processes, the precursor compound is vaporized and passed into the reactor by means of a carrier gas in gaseous form. Accordingly, the precursor compound is converted to the gas phase before being fed to the substrate. In aerosol assisted CVD (AA-CVD), the precursor compound is dissolved in a solvent and fed to the substrate by means of a carrier gas, for example in the form of a liquid / gas aerosol, the precursor compound being in liquid form and only near the surface of the substrate, which is preferably heated or tempered, converted into the gaseous form. Accordingly, the precursor compound is first converted into the gas phase after it has been fed into the environment of the substrate.

Suitable methods are CVD and ALD methods. Among the CVD methods, for example, thermal CVD methods, plasma CVD methods or laser-assisted CVD methods are suitable. Preferred methods for deposition from the gas phase are selected from the group comprising thermal CVD processes, Combustion Chemical Vapor Deposition (C-CVD), pulsed or direct liquid injection C VD processes such as Pulsed Spray Evaporation Chemical Vapor Deposition (PSE-CVD) or Direct Liquid Injection Metal Organic Chemical Vapor Deposition (DLI-MOCVD), and / or Aerosol Assisted Chemical Vapor Deposition (AA-CVD).

Preferred CVD processes are thermal CVD processes. In preferred embodiments, the CVD method is not a plasma CVD method. It is of great advantage that the method according to the invention can lead to the deposition of metal layers in the case of the very mild conditions of thermal CVD methods compared to plasma methods.

Particularly preferred thermal CVD processes are thermal CVD processes in hot wall or cold wall CVD reactors. In thermal CVD processes in hot wall reactors, the entire reactor is heated to the desired temperature, in thermal CVD processes in cold wall reactors, the substrate is heated.

Very particular preference is given to organometallic CVD processes (MOCVD), in particular pulsed or direct liquid injection C VD processes using organometallic precursor compounds, Direct Liquid Injection Metal Organic Chemical Vapor Deposition (DLI-MOCVD) or Pulsed Spray Evaporation Chemical Vapor Deposition (PSE-CVD) method.

An advantage of the pulsed or direct liquid injection C VD processes using organometallic precursor compounds, DLI-MOCVD, is, for example, that higher growth rates can be achieved. Preferably, the deposition takes place in the kinetically controlled region of the deposition. This kinetically controlled region of deposition is dependent on the precursor compound and the reducing fluid used. This range can be determined by methods known to the person skilled in the art, for example by the application of an Arrhenius diagram in which, for example, the experimentally determined growth rate is plotted against the substrate temperature used. From the slope, according to the Arrhenius equation (I), k = A exp (-Ea / RT), where k is the growth rate, T is the deposition temperature, R is the gas constant and Ea is the activation energy, the activation energy can be determined.

The growth rate of the deposited metal layer can be determined, for example, from the known duration of the deposition and the preferably gravimetrically determinable layer thickness. For this purpose, the substrate is weighed before and after the coating. From the determined weight of the deposited layer, taking into account the density of the metal layer, the volume of the layer is calculated. The morphology or crystallinity of the metal layer can be determined by means of scanning electron microscopy (SEM) or X-ray diffractometry (XRD) and the composition by means of energy-dispersive X-ray analysis (EDX). It is assumed for the calculation that the layer is non-porous and there are no impurities, which can likewise be determined by means of scanning electron microscopy (SEM) and energy-dispersive X-ray analysis. The thickness of the deposited layer is then available as a quotient of volume and known area of the coated substrate.

A suitable growth rate is adjustable via a variation of the process parameters, in particular selected from the group comprising temperature of the substrate, evaporation temperature of the precursor compound, pressure in the reactor and / or gas flow of the carrier gas. This makes it possible to adjust the availability of the precursor compound on the substrate. The growth rate of deposition can be varied widely. It is an advantage of the method according to the invention that high growth rates of the deposition can be achieved. In preferred embodiments of the method, metal layers having a growth rate in the range of> 0.5 nm / min to <100 nm / min, preferably in the range of> 10 nm / min to <30 nm / min, can be applied.

This can provide the advantage that deposition of metal layers can occur at high speed.

For example, it has been found that use of alcohols such as ethanol as an organic reactant, for example in the case of Ag (hfac) COD, can increase the growth rate by a factor of 3.

It is an advantage of the method according to the invention that metal layers of any thickness can be applied. The inventive method allows the application of thin as well as thick layers, and is thus suitable for coating substrates for a variety of applications. For example, layers with a layer thickness of up to 1 mm can be applied, as they are used as corrosion protection or for decorative applications. For example, metal layers with a layer thickness in the range of> 0.1 nm to <1 mm can be applied. Preferably, metal layers with a layer thickness in the range of> 0.3 nm to <200 nm, preferably in the range of> 0.5 nm to <100 nm, particularly preferably in the range of> 0.5 nm to <25 nm are applied.

In particular, the inventive method allows the deposition of very thin metal layers. Advantageously, metal layers with a layer thickness in the range of in the range of> 0.1 nm to <10 nm, preferably in the range of> 0.3 nm to <5 nm can be applied. In particular, it is of great advantage that very thin layers, for example in a range of> 0.3 nm to <10 nm, can be applied, which can completely cover the substrate. This allows, for example, applications in the field of optoelectronics or sensors.

Of particular advantage here is that thin metal layers can be produced, which are uniform, can have a uniform density and / or can be free of cracks. In particular, the layers are preferably non-porous. This can further lead to the deposited layers having uniform magnetic and / or electrical properties.

It is of very particular advantage that the deposition of metal layers can proceed according to the method of the invention using organic reducing agents as the solvent and the only reducing agent without incubation. This makes it possible to control the deposition process, which is not achievable in known deposition methods due to the incubation time, which can be in the range of several minutes to hours depending on the substrate to be coated.

Thus, it was found that when using metal β-diketonates and liquids having a reducing property, in particular alcohols such as ethanol or methanol, as the solvent and sole reducing agent, metal layers could be formed already at a deposition time of only a few seconds, forming the substrate completely cover. This is of significant advantage over a deposition which takes place only after an incubation period, since under such conditions neither such thin layers can be applied nor the resulting layers have a corresponding uniformity. In particular, it could be stated that deposited metal layers, in particular nickel, silver and copper layers had an electrical resistance which differed only slightly from the resistance of the pure metal. This is especially available without aftertreatment of the deposited metal layer. An advantage of the method according to the invention is that it makes it possible to provide metal layers in a purity which corresponds to the purity of metal layers which are deposited by means of multi-step processes using hydrogen as the reducing agent.

Thus, a great advantage of the method according to the invention is to be able to deposit metal layers of high quality, which can be done in a one-step process without the addition of further reducing agents, and also have much lower hazard potential as for example in the usual use of highly flammable and in air explosive hydrogen gas is the case.

The deposited according to the method of the invention metal layers are further advantageously formed smooth.

A significant advantage of the method according to the invention is that it makes it possible to provide metal layers which are smooth, completely cover the substrate even during the deposition of thin layers and / or have a uniform crystalline morphology.

In particular, metal layers, for example nickel, cobalt, silver and / or copper layers in the region of a layer thickness thinner than 25 nm, may permit an application in the field of magnetic and / or electrical applications.

Furthermore, for example, nickel, cobalt and / or iron layers in the range of a layer thickness thinner than 25 nm allow an application in the field of magnetic applications, in particular of the magnetic storage media. Next are, for example, feeds with semi-precious metals and in particular with non-precious metals, for example nickel, cobalt and / or iron layers, usable in the field of corrosion protection.

The application of metal layers according to the invention can take place in varying pressure ranges, for example at reduced or elevated pressure, for example also above 1 bar. The application of metal layers according to the invention is preferably carried out under reduced or atmospheric pressure, preferably at a pressure in the range of> 1 mbar to <1 bar, preferably in the range of> 10 mbar to <200 mbar, more preferably in the range of> 20 mbar to <100 mbar.

The application of metal layers according to the invention can take place in the case of a gas flow of the carrier gas, which can vary within wide ranges. For example, can be deposited without gas flow, or at very high gas flow. Preferably, the deposition takes place at a gas flow in the range> 0.5 slm to <2 slm, particularly preferably in the range of> 1 slm to <1.5 slm.

The deposition of metal layers according to the method of the invention can be carried out at temperatures of the substrate, which can vary within wide limits. The substrate may be tempered, for example. In preferred embodiments of the method according to the invention, the deposition is carried out at a temperature of the substrate in the range of> 400 K to <1000 K, preferably in the range of> 440 K to <800 K, preferably in the range of> 460 K to <680 K. ,

For example, it has been found that deposition of nickel (II) acetylacetonate using the organic reactant ethanol can occur at much lower temperatures than when using hydrogen as the reducing agent. That the inventive method allows a coating at lower temperatures, is particularly advantageous because, for example, a coating at temperatures below 200 ⁰ C allows a coating of polymers with a metal layer.

The method according to the invention is suitable for the coating of different substrates, for example for coating metal substrates, metal oxide substrates, semiconductor substrates, glass and / or ceramic substrates. Preferably, the substrate is selected from the group comprising silicon substrates, metal substrates, metal oxide substrates, glass substrates, ceramic substrates, in particular SiC or high-temperature ceramics.

It is a significant advantage of the method according to the invention that metal oxides can be coated as substrates with a metal layer. The process according to the invention, which uses organic reducing agents, makes it possible to coat substrates sensitive to these, preferably mild reducing agents, with metal layers, such as metal oxide substrates.

For example, a sensitive substrate such as cobalt oxide, CO3O4, can be coated with a metal without the metal oxide itself being reduced. By using, for example, alcohols, especially ethanol as a reducing agent, a sensitive substrate can be protected from reduction to the metal. In particular, a deposition of metals such as silver on metal oxides is made possible, which is not possible by processes using strong reducing agents such as hydrogen.

Another advantage of the method according to the invention is that the deposition is made possible, for example, also on glass. A metal deposition is possible in particular without the use of a germ or a germ layer. This is a special advantage in particular compared with hydrogen-based processes, which often require a seed layer, in particular for deposition on glass.

The inventive method allows, for example, metal-containing precursor compounds containing various metals can be dissolved in an organic reducing agent, in particular by dissolving in an organic reducing agent different metal-containing precursor compounds can be dissolved in different or equal molar concentrations, this allows, from the dissolved precursor compounds a mixture different metals, for example, in the form of a mixture or an alloy to be deposited. Of particular advantage here is that the composition of an alloy to be deposited is adjustable by the different or equal molar concentrations of the dissolved precursor compounds.

In preferred embodiments of the process, a mixture of at least two, preferably a mixture of several, preferably in the range of 2 to 5 metal-containing precursor compounds, dissolved in the same or different concentrations in the organic reducing agent and the respectively released metals to form a material gradient, multilayer coatings and / or an alloy deposited on the substrate. For example, the metals released in each case can be deposited in different proportions of the respective metals to form a material gradient in a layer.

Preferred mixtures of useful mixtures of metal-containing precursor compounds include, for example, precursor compounds of Co and Ni, Co and Cu and / or Ag and Cu. In preferred embodiments of the process, a mixture of at least two, preferably a mixture of several, preferably in the range of 2 to 5 metal-containing precursor compounds, used in the same or different concentrations and the respectively released metals to form a material gradient, multilayer coatings and / or an alloy are deposited on the substrate. In particular, mixtures of semi-precious, non-noble and / or very base metals can be deposited.

Also, preferred mixtures of useful mixtures of metal-containing precursor compounds include, for example, precursor compounds of Ag and Ni and / or Ni and Cu.

Particularly preferred mixtures of useful mixtures of metal-containing precursor compounds include, for example, precursor compounds of Fe and Ni and / or Ni and Co.

In preferred embodiments, mixtures of semi-precious, non-noble and / or very base metals are separable.

Advantageously, alloys of the semi-precious, non-noble and / or very base metals can be deposited using the method according to the invention. In particular, alloys of non-noble and / or very base metals can be deposited. For example, Ag-Ni and / or Ni-Cu alloys are depositable. In preferred embodiments, Ni-Fe, Fe-Co and / or Co-Ni alloys are depositable.

Surprisingly, it has furthermore been found that a desired stoichiometry of the precipitation product can be reliably adjusted by the preferred CVD method, in particular with liquid injection in the deposition of metal alloys. This enables deposition of alloys which may have a uniform composition over the entire substrate and / or the entire thickness of the layer.

The stoichiometry can be adjusted in a targeted manner, for example by a specific mixture of the precursor compounds containing at least two different metals. These may, for example, be contained in the same pulse in any ratio. An advantage of the method according to the invention is that a constant stoichiometry can be set through the entire layer. Preferred mixtures may be, for example, mixtures of copper and nickel, preferably in the form of nickel (II) acetylacetonate and copper (II) acetylacetonate, which may be dissolved in a predetermined mixing ratio in an organic reducing agent, in particular an alcohol, for example in ethanol or methanol.

With the method according to the invention, coatings which can contain at least two different metals in which the composition is gradually variable with the thickness of the layer can advantageously be produced. This can be provided, for example, by varying the composition of the mixture containing the metal-containing precursor compound in an organic reducing agent during deposition.

With the method according to the invention it is furthermore advantageously possible to produce multilayer feeds which comprise a plurality of layers containing the same or different metals. This can be made available, for example, by initially introducing at least two or more mixtures each containing a metal-containing precursor compound in an organic reducing agent, and alternately separating the mixtures, for example by alternating pulses of the various mixtures. The inventive method allows the deposition of one or more metal layers containing the same or different metals.

For example, with the method according to the invention, a plurality of metal layers in the range of> 2 to <50 metal layers, preferably in alternating form, can be applied to a substrate. With the method according to the invention, it is advantageously possible to apply layers which allow the coated substrates to be used for optical applications. It is also possible to apply metal layers in the range of> 2 to <10 metal layers.

Advantageously, the method according to the invention allows the deposition of metal layers on substrates making them usable for example for magnetic applications, for example for multilayer and granular layer systems of ferromagnetic and non-ferromagnetic metals, and for tunneling barriers insulating multi-layer and granular layer systems of ferromagnetic and non-ferromagnetic metals.

The method according to the invention can advantageously be used for applying at least one metal layer to substrates.

Another object of the invention relates to a substrate coated with at least one metal layer applied according to one of the preceding claims.

Examples and figures which serve to illustrate the present invention are given below.

In the figures shows: Fig. 1 is a plot of the growth rate of a copper layer for the various solvents.

It can be seen that the growth rate of the copper layer is significantly higher for methanol and ethanol than for tetrahydrofuran.

Fig. 2 is a plot of the layer thickness of a copper layer relative to the substrate temperature for methanol and tetrahydrofuran as a solvent. It can be seen that the layer thickness of the copper layer in the case of methanol, in contrast to tetrahydrofuran, increases with an increase in the substrate temperature.

3 shows an X-ray diffractometer image of a deposited iron layer.

It can be seen that a pure cubic crystalline iron phase was deposited.

Example 1:

Coating of a glass substrate with a copper layer

The coating was carried out in a cold wall CVD reactor in the form of a pulse spray evaporation CVD process.

In essence, the reactor comprised three extension parts, an evaporator zone (T1), a carrier gas zone (T3) and a transport zone (T4). These were located above the cold wall CVD chamber. In the CVD chamber ceramic blocks were arranged, which served as insulating pedestals. Over this a flat heating device was arranged.

All areas were heated separately, whereby the respective temperatures were controlled by means of a temperature control unit (HT-60, Horst). Nitrogen served as a carrier gas and was heated to a temperature of 498 K to give cooling effects and thus a Prevent condensation of the precursor compound. The precursor compound was sprayed via a pulsed spray nozzle into the evaporation zone (T1). This evaporation zone was heated to a temperature of 453 K and transported with the flow of nitrogen into the subsequent transport zone (T4), which was heated to a higher temperature of 513 K. The gas pressure in the system was set at 45 mbar (Balzer Instruments), controlled and kept constant. The injection system is located in the evaporation zone (Tl) and was placed laterally in the evaporation zone to prevent dripping. A liquid nitrogen cooled cold trap was placed between the reactor and the centrifugal pump to trap the evaporated solvent before it reached the pump oil.

The substrate temperature was 673 K and the deposition pressure was 45 mbar. The precursor compound was fed to the reactor by means of nitrogen as carrier gas with 1 slm (slm = standard liters per minute).

The substrate used was glass fragments of 1.8 x 1.8 cm ² . The glass substrate (1.8 × 1.8 cm) was washed once in the ultrasonic bath with scouring powder and then twice with warm distilled water and then with acetone and dried in air. The coating chamber was evacuated to 5 mbar using a centrifugal pump (VacUUbrand). Subsequently, the reactor was purged with nitrogen into the system with a slm using a mass flow controller (Model No. FC-260, Tylan) and the pressure increased to 45 mbar. Subsequently, the evaporation zone, the carrier gas and the substrate were simultaneously adjusted to the desired temperature. The temperature of the various zones was controlled by means of thermocouples and resistance heaters. Substrates were cooled in vacuo to prevent oxidation. Copper (II) acetylactonate (Cu (II) (acac) 2) (Sigma-Aldrich, 98%) was dissolved in a concentration of 5 mM in ethanol (Prolab, preferably analytical grade). The necessary amount of the copper (II) acetylactonate was weighed with a microbalance (Sauter Feinwaage, type 404/11). The mixture was placed in ethanol in an evaporator, heated to 303 K to 323 K (30 ⁰ C to 50 ⁰ C) and shaken constantly in an ultrasonic bath to maintain the complete solution.

The 5 mM solution of copper (II) acetylactonate in ethanol was introduced into the reactor with a pulse duration of 25 ms and a pulse frequency of 1 Hz during a coating time of 30 minutes to coat the substrate.

After coating, the substrate was cooled in vacuo to prevent oxidation.

The thickness of the deposited metal layer was determined gravimetrically. For this, the glass substrate was weighed before and after the coating, with an increase in weight resulting in weight gain in the range of 100 μg. Considering the density of the copper of 8.92 mg / cm ³ , the volume and the thickness of the deposited layer were calculated to be 35 nm. At a deposition time of 30 minutes, the growth rate of the deposited copper layer was 1.2 nm per minute.

Subsequently, the glass fragments were placed under a high-resolution

X-ray diffractometer (X'PERT per MRD, PHILIPS) using CuK ₀₁ (λ = 1.5418 Å) radiation examined at a geometry of θ to 2Θ. The morphology of the layer was examined by scanning electron microscopy in an XL-30 ESEM (PHILIPS) equipped with an EDX spectrometer (PHILIPS). It was found that a layer of pure and crystalline copper was deposited. Example 2

Following the conditions of Example 1, the coating was repeated with a 5 mM solution of copper (II) acetylactonate in methanol (ACROS Organics, preferably analytical grade).

There was a growth rate of 1.0 nm / min.

Example 3

Under the conditions corresponding to Examples 1 and 2, the coating was repeated with a solution of 5 mM copper (II) acetylactonate in tetrahydrofuran (THF), (Roth,> 99.5%). Using tetrahydrofuran as the solvent and reducing agent, the growth rate was 0.1 nm / min.

This shows that the use of ethanol and methanol as solvent and reducing agent have a significantly higher growth rate compared to the cyclic ether tetrahydrofuran.

The plot of the growth rate for the various solvents shown in FIG. 1 serves to clarify these test results.

Example 4

Investigation of the effect of the solvent on the layer growth

In order to investigate the reduction strength of methanol and the non-alcoholic solvent tetrahydrofuran was under Example 1 corresponding conditions, at a deposition pressure of 45 mbar and 1 slm nitrogen, the deposition at different substrate temperatures, 603 K, 643 K, 673 K and 683 K investigated.

Copper (II) acetylactonate was in each case dissolved in a concentration of 5 mM in methanol or THF. The deposition time was 30 minutes in each case.

It was found that when using methanol as the solvent and reducing agent, the layer thickness linearly increased with the substrate temperature, while the increase in the substrate temperature with the use of tetrahydrofuran showed no effect on the thickness of the deposited layer.

Furthermore, it was found that when using methanol, the deposited copper layer had a typical copper-red color.

This clearly shows the importance of the reducing power of methanol in the formation of copper layers. The plot of the layer thickness versus the substrate temperature for methanol and tetrahydrofuran as solvent shown in FIG. 2 serves to illustrate these test results.

Example 5

Coating of a glass substrate with a nickel layer

In essence, the reactor comprised three extension parts, an evaporator zone (T1), a carrier gas zone (T3) and a transport zone (T4). These were above the cold wall CVD Chamber arranged. In the CVD chamber ceramic blocks were arranged, which served as insulating pedestals. Over this a flat heating device was arranged.

All areas were heated separately, whereby the respective temperatures were controlled by means of a temperature control unit (HT-60, Horst). Nitrogen served as a carrier gas and was heated to a temperature of 498 K to prevent cooling effects and thus condensation of the precursor compound. The precursor compound was sprayed via a pulsed spray nozzle into the evaporation zone (T1). This evaporation zone was heated to a temperature of 453 K and transported with the flow of nitrogen into the subsequent transport zone (T4), which was heated to a higher temperature of 513 K. The gas pressure in the system was set at 45 mbar (Balzer Instruments), controlled and kept constant. The injection system is located in the evaporation zone (Tl) and was placed laterally in the evaporation zone to prevent dripping. A liquid nitrogen cooled cold trap was placed between the reactor and the centrifugal pump to trap the evaporated solvent before it reached the pump oil.

The substrate temperature was 533 K and the deposition pressure was 45 mbar. The precursor compound was fed to the reactor by means of nitrogen as carrier gas with 1 slm (slm = standard liters per minute).

The substrate used was glass fragments of 1.8 x 1.8 cm ² . The glass substrate (1.8 × 1.8 cm ² ) was washed once in the ultrasonic bath with scouring powder and then twice with warm distilled water and then with acetone and dried in air. The coating chamber was evacuated to 5 mbar using a centrifugal pump (VacUUbrand). Subsequently, the reactor was purged with nitrogen slm into the system using a mass flow controller (Model No. FC-260, Tylan) and the pressure was 45 mbar elevated. Subsequently, the evaporation zone, the carrier gas and the substrate were simultaneously adjusted to the desired temperature. The temperature of the various zones was controlled by means of thermocouples and resistance heaters. Substrates were cooled in vacuo to prevent oxidation.

Nickel (II) acetylactonate (Ni (II) (acac) 2) (Sigma-Aldrich, 98%) was dissolved in a concentration of 5 mM in ethanol (Prolab, preferably analytical grade). The necessary amount of nickel (IΙ) acetylactonate was weighed with a microbalance (Sauter fine scale, type 404/11). The mixture was placed in ethanol in an evaporator, heated to 303 K to 323 K (30 ⁰ C to 50 ⁰ C) and shaken constantly in an ultrasonic bath to maintain the complete solution.

The 5 mM solution of nickel (II) acetylactonate in ethanol was introduced into the reactor with a pulse duration of 25 ms and a pulse frequency of 1 Hz during a coating time of 2 minutes to coat the substrate.

The thickness of the deposited metal layer was determined gravimetrically. To this end, the glass substrate was weighed before and after the coating, with a weight gain resulting in weight gain in the region of 34 μg. Taking into account the density of the nickel of 8.91 mg / cm ³ , the volume and the thickness of the deposited layer were calculated to be 12 nm. At a deposition time of 2 minutes, the growth rate of the deposited nickel layer was 6 nm per minute.

Subsequently, the glass fragments were placed under a high-resolution

X-ray diffractometer (X'PERT per MRD, PHILIPS) using CuK ₀₁ (λ = 1.5418 Å) radiation examined at a geometry of θ to 2Θ. The morphology of the layer was fitted by scanning electron microscopy in an XL-30 ESEM (PHILIPS) examined with an EDX spectrometer (PHILIPS). It was found that a layer of pure and crystalline nickel was deposited.

Further, it was found that the deposited nickel layer had a metallic appearance and also a layer of 8 nm thickness had good electrical conductivity.

Example 6

Following the conditions of Example 5, the coating was repeated with a 5 mM solution of nickel (IΙ) acetylactonate in methanol (ACROS Organics, preferably analytical grade).

There was a growth rate of 1.2 nm / min.

Example 7

Coating of a glass substrate with an iron layer

The coating was carried out in a cold wall CVD reactor in the form of a pulse spray evaporation CVD process. In essence, the reactor comprised three extension parts, an evaporator zone (T1), a carrier gas zone (T3) and a transport zone (T4). These were located above the cold wall CVD chamber. In the CVD chamber ceramic blocks were arranged, which served as insulating pedestals. Over this a flat heating device was arranged.

All areas were heated separately, whereby the respective temperatures were controlled by means of a temperature control unit (HT-60, Horst). Nitrogen served as a carrier gas and was heated to a temperature of 498 K to give cooling effects and thus a Prevent condensation of the precursor compound. The precursor compound was sprayed via a pulsed spray nozzle into the evaporation zone (T1). This evaporation zone was heated to a temperature of 453 K and transported with the flow of nitrogen into the subsequent transport zone (T4), which was heated to a higher temperature of 503 K. The gas pressure in the system was set at 40 mbar (Balzer Instruments), controlled and kept constant. The injection system is located in the evaporation zone (Tl) and was placed laterally in the evaporation zone to prevent dripping. A liquid nitrogen cooled cold trap was placed between the reactor and the centrifugal pump to capture the vaporized solvent before it reaches the pump oil.

The substrate temperature was 643 K and the deposition pressure was 40 mbar. The precursor compound was fed to the reactor by means of nitrogen as carrier gas with 1 slm (slm = standard liters per minute).

The substrate used was glass fragments of 1.8 x 1.8 cm 2. The glass substrate (1.8 x 1.8 cm 2) was washed once in the ultrasonic bath with scouring powder and then twice with warm distilled water and then with acetone and dried in air. The coating chamber was evacuated to 5 mbar using a centrifugal pump (VacUUbrand). Subsequently, the reactor was purged with nitrogen into the system using a mass flow controller (Model No. FC-260, Tylan) and the pressure increased to 40 mbar. Subsequently, the evaporation zone, the carrier gas and the substrate were simultaneously adjusted to the desired temperature. The temperature of the various zones was controlled by means of thermocouples and resistance heaters. Substrates were cooled in vacuo to prevent oxidation. Iron (II) acetylactonate (Fe (II) (acac) 2) (Sigma-Aldrich, 95%) was dissolved in a concentration of 2.5 mM in ethanol (Prolab, preferably analytical grade). The necessary amount of the iron (II) acetyl lactonate was weighed with a microbalance (Sauter fine balance, type 404/11). The mixture was placed in ethanol in an evaporator, heated to 303 K to 323 K (30 ⁰ C to 50 ⁰ C) and shaken constantly in an ultrasonic bath to maintain the complete solution.

The 2.5 mM solution of ferrous acetylactonate in ethanol was introduced into the reactor with a pulse duration of 25 ms and a pulse frequency of 1 Hz during a coating time of 200 minutes for coating the substrate. These conditions resulted in a growth rate of deposited iron layer of 0.4 nm per minute on glass substrate.

Subsequently, the glass fragments were examined under a high-resolution X-ray diffractometer (X'PERT per MRD, PHILIPS) using the CuKa (λ = 1.5418 Å) radiation at a geometry of θ to 2Θ. The morphology of the layer was examined by scanning electron microscopy in an XL-30 ESEM (PHILIPS) equipped with an EDX spectrometer (PHILIPS). It was found that a layer of pure and crystalline iron was deposited.

Furthermore, it was found that the deposited iron layer had a metallic appearance and also a layer of <10 nm thickness had a good electrical conductivity.

The X-ray diffractometer image shown in FIG. 3 shows that a pure cubic crystalline iron phase was deposited.

Example 8 Under conditions similar to those of Examples 5 and 6, the coating was repeated with a solution of 5 mM nickel or cobalt (II) acetylactonate in n-butyl acrylate (Roth,> 99.5%).

Under these conditions, no metal layer was grown.

This shows that, in particular in the case of nickel and cobalt acetylacetonate, the organic reactant used, in particular alcohol, can effect deposition of metal layers.

Claims

A one-step process for applying at least one metal layer to a substrate by a gas phase chemical vapor deposition method wherein a substrate is coated with a metal layer by depositing a metallic phase metal precursor compound on the substrate, characterized dissolving the metal-containing precursor compound in a solvent, adding an organic reactant, and gasifying the metal-containing precursor compound and the organic reactant, releasing the metal from the metal-containing precursor compound by means of the organic reactant, thereby depositing the released metal onto the substrate ,

2. The one-step process of claim 1, characterized in that dissolving the metal-containing precursor compound in an organic reactant, this mixture is converted into the gas phase, wherein the metal is released from the metal-containing precursor compound by means of the organic reactant, wherein the released metal on the substrate is deposited.

3. Single-stage process according to claim 1 or 2, characterized in that the organic reactant is an organic reducing agent.

4. One-stage process according to one of the preceding claims, characterized in that one dissolves the metal-containing precursor compound in an organic reducing agent, this mixture is converted into the gas phase, wherein the metal is released from the metal-containing precursor compound by means of the organic reducing agent, wherein the released metal on the Substrate is deposited.

5. The method according to any one of the preceding claims, characterized in that the organic reducing agent is selected from the group consisting of alcohol (s), aldehyde (s), amine (s), ethers, thiol (s) and / or mixtures thereof, wherein Alcohol (s) are particularly preferred.

6. The method according to any one of the preceding claims, characterized in that the alcohol is selected from the group comprising primary, secondary and / or tertiary alcohols, preferably from the group comprising alcohols having a radical having 1 to 6 carbon atoms, preferably from the group comprising Methanol, ethanol, isopropanol, n-propanol, n-butanol, tert-butanol, phenol and / or mixtures thereof, particularly preferably from the group comprising methanol, ethanol, n-propanol and / or iso-propanol.

7. The method according to any one of the preceding claims, characterized in that organometallic precursor compounds, preferably selected from the group consisting of metal alkoxides, metal carbonyls, metal dithiocarbamates, metal borides, metal amidinates, metal carboxylates, metal dithiophosphates and / or metal diketonates, preferably selected from the group comprising metal β-diketonates, such as metal acetylacetonate, metal hexafluoroacetylacetonate and / or metal triisopropoxide used.

8. The method according to any one of the preceding claims, characterized in that the metal of the metal-containing precursor compounds is selected from the group comprising transition metals of the subgroups of the Periodic Table, preferably from the group comprising Fe, Ce, Rh, Ru, Co, Ni, Pd, Pt , Cu, Ag and / or Au, more preferably selected from the group comprising Ni, Fe, Co and / or Ag.

9. The method according to any one of the preceding claims, characterized in that the metal-containing precursor compound having a concentration in the range of> 0.1 mM to <50 mM, preferably in the range of> 1 mM to <50 mM, preferably in the range of> 5 mM to <25 mM, in the organic reducing agent, preferably dissolves in the reducing liquid.

10. The method according to any one of the preceding claims, characterized in that the method for the deposition from the gas phase is selected from the group of CVD method, preferably selected from the group comprising thermal CVD method, Pulsed Spray Evaporation Chemical Vapor Deposition, Direct Liquid Injection Metal Organic Chemical Vapor Deposition and / or Aerosol Assisted Chemical Vapor Deposition.

11. The method according to any one of the preceding claims, characterized in that a metal layer having a layer thickness in the range of> 0.1 nm to <1 mm, preferably in the range of> 0.3 nm to <200 nm, preferably in the range of > 0.5 nm to <25 nm.

12. The method according to any one of the preceding claims, characterized in that the metal layer with a growth rate in the range of> 0.5 nm / min to <100 nm / min, preferably in the range of> 10 nm / min to <30 nm / min applies.

13. The method according to any one of the preceding claims, characterized in that the substrate is selected from the group comprising silicon substrates, metal substrates, metal oxide substrates, glass substrates, ceramic substrates, in particular SiC or high temperature ceramics.

14. The method according to any one of the preceding claims, characterized in that dissolving a mixture of at least two metal-containing precursor compounds in the organic reducing agent and depositing each of the released metals to form a gradient of material, multilayers and / or an alloy on the substrate.

15. The method according to any one of the preceding claims, characterized in that applying a plurality of metal layers, preferably in the range of> 2 to <50 metal layers, preferably in the range of> 2 to <10 metal layers, preferably in an alternating form, applied to the substrate.

16. Use of the method according to one of the preceding claims for applying at least one metal layer to a substrate.

17. Substrate coated with at least one metal layer applied according to one of the preceding claims.