Metal compounds for ALD applications

Abstract

The present invention relates to chromium, molybdenum and tungsten complexes and a method of using these complexes as precursors for deposition of metal containing films, in particular by atomic layer deposition (ALD).

Description

[0001] Metal Compounds for ALD Applications

[0002] Field

[0003] The present invention relates to chromium, molybdenum and tungsten complexes and a method of using these complexes as precursors for deposition of metal-containing films, in particular by atomic layer deposition (ALD).

[0004] Background Art

[0005] Metal-containing thin films are used in semiconductor, electronics and nanotechnology applications. Examples of such applications include capacitor electrodes, gate electrodes, adhesive diffusion barriers and integrated circuits. Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) have been applied as the main deposition techniques for producing thin films for semiconductor devices, as they have the advantages of enhanced compositional control, high film uniformity, and effective control of doping. Moreover, CVD and ALD processes provide excellent conformal step coverage on highly non-planar geometries associated with modern microelectronic devices. These methods enable the achievement of conformal films (metal, metal oxide, metal nitride, metal sulfide, metal silicide, and the like) through chemical reactions of metal-containing compounds (precursors). The chemical reactions occur on surfaces which may include metals, metal oxides, metal nitrides, metal silicides, and other surfaces. In CVD and ALD, the precursor molecule plays a critical role in achieving high quality films with high conformality and low impurities. The temperature of the substrate in CVD and ALD processes is an important consideration in selecting a precursor molecule. The precursor needs to have an appropriate vapor pressure and sufficient thermal stability. Furthermore, it needs to be vaporizable in a stable supply amount for forming a thin film by CVD or ALD method. The temperature of the substrate in CVD and ALD processes is an important consideration in selecting a precursor molecule. The precursor molecules should preferably be stable at typical substrate temperatures, e.g. in the range of room temperature to 600 °C. Furthermore, the preferred precursor is capable of being delivered to the reaction vessel in a liquid or gaseous phase. The liquid phase of precursors at volatilization temperature generally provides a more uniform delivery of the precursor to the reaction vessel than solid phase precursors. While it is sufficient that the precursor is a liquid at delivery temperature, it is preferable that the precursor is a liquid at room temperature or close to room temperature. This has the advantage that condensation or solidification is less likely to occur, if there is any cold spot in the precursor delivery system. Furthermore, the handling of a compound which is a liquid at or slightly above room temperature is technically easier, e.g. the filling and cleaning of the vessels from which the precursor is applied.

[0006] CVD is a chemical process whereby precursors are used to form a thin film on a substrate surface. In a typical CVD process, the precursors are passed over the surface of a substrate e.g., a wafer) in a low pressure or ambient pressure reaction chamber. The precursors react and / or decompose on the substrate surface creating a thin film of deposited material. Plasma can be used to assist in reaction of a precursor or for improvement of material properties. Volatile by-products are removed by gas flow through the reaction chamber. A variety of parameters have a direct or even subtle impact on controlling the thickness of deposited films, including temperature, pressure, gas flow volumes and uniformity, chemical depletion effects, and time.

[0007] ALD is a chemical method for the deposition of thin films using two or more different vapor phase precursors which are separated during the reaction. The surface of a substrate onto which the film is to be deposited is exposed to a dose of vapor of a first precursor producing a monolayer on the substrate surface. Then any excess unreacted vapor from that precursor is pumped away, e.g. by inert gas purges. Next, a vapor dose of a second precursor or co-reactant is passed over the substrate surface and allowed to react with the first precursor forming a second monolayer over the first- formed monolayer on the substrate surface. Plasma may be used to assist the reaction of a precursor or co-reactant or for improvement in materials quality. This cycle of steps can be repeated to build up thicker films. One particularly important aspect of this process is that the ALD reactions are self-limiting in that only a certain maximum thickness can form in each cycle, after which no further deposition occurs during that cycle, even if excess reactant is available. Because of this self-limiting character, ALD reactions produce coatings with highly uniform thicknesses not only on flat substrate surfaces, but also into narrow holes and trenches as well as other three-dimensional surfaces, which renders this technique indispensable for the semiconductor industry.

[0008] Important properties that the compound to be used as a thin-film forming precursor (reactant) for CVD or ALD is required to have are as follows: its vapor pressure is high; its melting point is low, and the compound is preferably a liquid at or slightly above room temperature; its thermal stability is high; and the compound can produce a high- quality thin-film with high productivity, i.e. the reactivity towards the surface, the coreactant and the deposited material is high and the reactions are clean, i.e. the reactions do essentially not produce any undesired byproducts on the surface. Molybdenum-containing thin films have attracted attention in the electronics industry due to their lower resistivity, lower tendency to electromigration and thermal stability compared to other metals like copper. Molybdenum is a low-resistivity refractory metal that has been used in microelectronic devices. Molybdenum has a high melting point, high thermal conductivity, a low coefficient of thermal expansion, and low electrical resistivity. Molybdenum or molybdenum-containing films have been used or proposed to use as a diffusion barrier, electrode, photomask, interconnect, or as a low-resistivity gate structure. Molybdenum is a candidate for replacing tungsten used in memory chips, logic chips, and other devices that include polysilicon-metal gate electrode structures. Molybdenum films may be used as low resistivity electrical connections in the form of vertical interconnects and / or horizontal interconnects through which current flows, as vias between adjacent metal layers, and as contacts between a first metal layer and the devices on a substrate. A thin molybdenum-containing film can also be used in some organic light emitting diodes, liquid crystal displays, and in thin film solar cells and photovoltaics.

[0009] Tungsten is utilized as a barrier layer, interconnect material, and contact material in the production of advanced semiconductor devices. Its high melting point, excellent electrical conductivity, and compatibility with other materials make it an essential component in the fabrication of integrated circuits, ensuring reliable performance and electrical connectivity.

[0010] Chromium is used for thin film deposition, corrosion protection, and wear-resistant coatings. It is also employed in the creation of magnetic materials, decorative coatings, and as a component in various alloy systems.

[0011] Accordingly, there is a need for improved precursors for depositing a molybdenum- containing film on a substrate. In particular, there is ongoing need for halogen-free molybdenum precursors which are liquid at room temperature or at low temperature, have relativity high vapor pressure, high thermal stability, and reactivity. Most of the known molybdenum precursors contain molybdenum in high oxidation state, such as oxidation state 4 to 6, which typically results in high resistivity molybdenum-containing films. Low oxidation state molybdenum complexes, such as oxidation state 0 to 4, are desired for deposition of low resistivity molybdenum-containing films.

[0012] Few precursors of Group 6 metals (chromium, molybdenum, tungsten) in formal oxidation state 0 with neutral ligands are known for use in ALD applications. These precursors are mostly made from carbonyls, arenes and / or dienes. Some examples for known precursors are Cr(CO)e, Cr(CO)3(anisol), Mo(CO)e, Mo(ethylbenzene)2, Mo(xylene)2 or Wo(CO)e.

[0013] Chromium, molybdenum and tungsten bis(arene) precursors are a series of organometallic compounds of the formula M(arene)2 where M is Cr, Mo or W and the arene is the same or different and is unsubstituted or substituted benzene, such as benzene, toluene, mesitylene, ethylbenzene, diethylbenzene and xylene. Such bis(arene) complexes as precursors for ALD applications are known, for example from WO 2023 / 154404, US 2022 / 0372053, WO 2024 / 054387 and WO 2024 / 030729. However, the synthesis of such bis(arene) metal complexes is described to be difficult, since the yields vary from 50 to 70 %. At least some of these precursors have an unsufficient thermal stability at temperatures at which the precursor’s vapor pressure is sufficiently high to deliver appropriate amounts of the precursor. Another drawback of the synthesis is the limited selection of arenes. Only methyl-substituted arenes like toluene, xylene or mesitylene lead to an isolation of pure compounds. Other arenes like ethyl benzene or isopropyl benzene undergo a Friedel-Crafts reaction during synthesis, resulting in a multiple intramolecular alkylation of the respective alkyl benzene in a statistic ratio of one to four. Furthermore, all reported pure bis(arene) molybdenum complexes with methyl-substituted arenes are solids at room temperature. Other examples like the commercially available Mo(ethylbenzene)2 can be isolated as a liquid at room temperature, as long as it contains a mixture of differently substituted compounds described as Mo(Etxbenzene)2 (x = 0 to 4). In contrast, pure Mo(ethyl- benzene)2 has a melting point above room temperature.

[0014] Another interesting class of ligands, which is an isomer of the arenes and has similar electronic properties, are the pentafulvenes. They can act as a six electron donating ligand (formal 4 + 2 TT donor) and since they are easy to modify they were used to stabilize different transition metal complexes. For example, carbonyl complexes of the general formula M(CO)3(fulvene) (with M = Cr, Mo, W and fulvene = dimethylfulvene, diethylfulvene, dicyclopropylfulvene and diphenylfulvene) are described in J. Organomet. Chem. 1977, 134, 31-36 and Chem. Ber. 1978, 111 , 817-818, but show poor stability at room temperature. Some of the compounds have not even been isolated, as they decomposed already during work up.

[0015] Some heteroleptic tungsten and molybdenum complexes with arene and fulvene ligands of the formula M(arene)(fulvene) (with M = Mo, W; arene = benzene, toluene and fulvene = dimethylfulvene and diphenylfulvene) are described in J. Chem. Soc. Dalton Trans. 1985, 2037-2049. All complexes were isolated as solids and structurally discussed. No application of these complexes is disclosed.

[0016] There is still an on-going need for new and improved Group 6 precursors with the metal in the formal oxidation state 0 for use in ALD applications. Accordingly, an object of the present invention is to provide novel compounds, which have high vapor pressures, low melting points, high reactivity in an ALD process and can produce high-quality thin films with high productivity when used as a thin film forming raw material.

[0017] Surprisingly, it was found that Group 6 metal complexes comprising one arene ligand and one fulvene ligand have low melting points with several complexes being liquid at room temperature. Furthermore, they have appropriate volatility while being thermally stable and can be employed in a CVD or ALD process to form a chromium, molybdenum or tungsten containing thin film. Such compounds are therefore the subject of the present invention.

[0018] Summary

[0019] The disclosed and claimed subject matter is directed to a compound of the following formula (1):

[0020] Formula (1 ) wherein the symbols have the following meanings:

[0021] M is chromium, molybdenum or tungsten;

[0022] R1, R2, R3, R4, R5, R6, R7, R8, R9, R10are each independently selected from the group consisting of H, D, F, Cl, Br, I, a linear alkyl group having 1 to 6 carbon atoms or a branched or cyclic alkyl group having 3 to 6 carbon atoms or an alkoxy or thioalkyl group, wherein the alkyl group of the alkoxy or thioalkyl group is selected from a linear alkyl group having 1 to 6 carbon atoms or a branched or cyclic alkyl group having 3 to 6 carbon atoms, or a dialkylamino group wherein each alkyl group of the dialkylamino group is independently selected from a linear alkyl group having 1 to 6 carbon atoms or a branched or cyclic alkyl group having 3 to 6 carbon atoms; where two adjacent substituents R1to R6may be linked to each other to form a ring and / or where where two adjacent substituents R7to R10may linked to each other to form a ring and / or where one of the substituents R1to R6and one of the substituents R7to R10may be linked to each other;

[0023] R11, R12are each independently a H, D, linear alkyl group having 1 to 6 carbon atoms, a branched or cyclic alkyl group having 3 to 6 carbon atom, an alkoxy or thioalkyl group, wherein the alkyl group of the alkoxy or thioalkyl group is selected from a linear alkyl group having 1 to 6 carbon atoms or a branched or cyclic alkyl group having 3 to 6 carbon atoms, or a dialkylamino group wherein each alkyl group of the dialkylamino group is selected from a linear alkyl group having 1 to 6 carbon atoms or a branched or cyclic alkyl group having 3 to 6 carbon atoms; where R11and R12may be linked to each other to form a ring; the following compounds are excluded from the invention:

[0024] The disclosed and claimed subject further includes compositions and formulations comprising the compound of formula (1), methods of using the compound of formula (1) as precursor for deposition of metal-containing films, and metal-containing films derived from the compound of formula (1).

[0025] Detailed description

[0026] In the following, the ligand comprising the substituents R1to R6is also referred to as “benzene ligand” or “arene ligand”, and the ligand comprising the substituents R7to R12is also referred to as “fulvene ligand”.

[0027] Furthermore, the metals chromium, molybdenum and tungsten are also referred to as Group 6 metals or as metals in general. In the context of the present invention, the term "alkyl group" is used as an generic term for linear, branched or cyclic alkyl groups. A linear alkyl group having 1 to 6 C atoms is methyl, ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl. A cyclic alkyl group in the context of this invention is understood to mean a monocyclic or bicyclic group. A cyclic alkyl group having 3 to 6 C atoms is, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclopropyl, methylcylobutyl or methylcyclopentyl. A branched alkyl group having 3 to 6 C atoms is, for example, iso-propyl, iso-butyl (2-methyl-prop-1-yl), sec-butyl (2-propyl), tert-butyl, sec-pentyl (2-pentyl), 3-pentyl, 2-methyl-butyl, iso-pentyl (iso-amyl, 3-methyl-butyl), 3-methyl-but-2-yl, 2-methyl-but-2-yl, neo-pentyl (2,2- dimethylpropyl), 2-hexyl or 3-hexyl.

[0028] The wording that two or more radicals together may form a ring system is understood to mean the formation of an aliphatic or heteroaliphatic ring, and, in the context of the present description, should be understood to mean that the two radicals are joined to one another by a chemical bond with formal elimination of two hydrogen atoms. This is illustrated by the following scheme:

[0029] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0030] The use of the terms "a", "an", "the" and similar referents in the context of describing the disclosed and claimed subject matter (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms ( / .e., meaning “including, but not limited to”) unless otherwise noted. The use of the term “comprising” or “including” in the specification and the claims includes the narrower language of “consisting essentially of’ and “consisting of.” Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it was individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the disclosed and claimed subject matter and does not pose a limitation on the scope of the disclosed and claimed subject matter unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed and claimed subject matter.

[0031] Embodiments of the disclosed and claimed subject matter are described herein, including the best mode known to the inventors for carrying out the disclosed and claimed subject matter. Variations of those embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the disclosed and claimed subject matter to be practiced otherwise than as specifically described herein. Accordingly, the disclosed and claimed subject matter includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosed and claimed subject matter unless otherwise indicated herein or otherwise clearly contradicted by context.

[0032] The compound according to the present invention is also referred to as “precursor” or “reactant” when the use of the compound in CVD or ALD deposition techniques is described.

[0033] For ease of reference, “microelectronic device” or “semiconductor device” corresponds to semiconductor wafers having integrated circuits, memory, and other electronic structures fabricated thereon, and flat panel displays, phase change memory devices, solar panels and other products including solar substrates, photovoltaics, and microelectromechanical systems (MEMS), manufactured for use in microelectronic, integrated circuit, or computer chip applications. Solar substrates include, but are not limited to, silicon, amorphous silicon, polycrystalline silicon, monocrystalline silicon, CdTe, copper indium selenide, copper indium sulfide, and gallium arsenide on gallium. The solar substrates may be doped or undoped. It is to be understood that the term “microelectronic device” or “semiconductor device” is not meant to be limiting in any way and includes any substrate that will eventually become a microelectronic device or microelectronic assembly. As defined herein, the term “barrier material” corresponds to any material used in the art to seal the metal lines, e.g., copper interconnects, to minimize the diffusion of said metal, e.g., copper, into the dielectric material. Preferred barrier layer materials include tantalum, titanium, ruthenium, hafnium, and other refractory metals and their nitrides and silicides.

[0034] “Substantially free” is defined herein as less than 0.001 wt%. “Substantially free” also includes 0.000 wt%. The term “free of” means 0.000 wt%. As used herein, "about" or “approximately” are intended to correspond to within ± 5% of the stated value.

[0035] In all such compositions, wherein specific components of the composition are discussed in reference to weight percentage (or “weight %” or “wt%”) ranges including a zero lower limit, it will be understood that such components may be present or absent in various specific embodiments of the composition, and that in instances where such components are present, they may be present at concentrations as low as 0.001 wt%, based on the total weight of the composition in which such components are employed. All percentages of the components are weight percentages and are based on the total weight of the composition, that is, 100%.

[0036] Moreover, when referring to the compositions described herein in terms of weight % or wt%, it is understood that in no event shall the wt% of all components, including non- essential components, such as impurities, add to more than 100 wt%. In compositions “consisting essentially of’ recited components, such components may add up to 100 wt% of the composition or may add up to less than 100 wt%. Where the components add up to less than 100 wt%, such composition may include some small amounts of a non-essential contaminants or impurities. For example, in one such embodiment, the formulation can contain 2 wt% or less of impurities. In another embodiment, the formulation can contain 1 wt% or less than of impurities. In a further embodiment, the formulation can contain 0.05 wt% or less than of impurities. In other such embodiments, the constituents can form at least 90 wt%, more preferably at least 95 wt% , more preferably at least 99 wt%, more preferably at least 99.5 wt%, most preferably at least 99.9 wt%, and can include other ingredients that do not or not significantly affect the deposition process. Otherwise, if no significant non-essential impurity component is present, it is understood that the composition of all essential constituent components will essentially add up to 100 wt%.

[0037] Any reference to “one or more” or “at least one” includes “two or more” and “three or more’ and so on. The headings employed herein are not intended to be limiting; rather, they are included for organizational purposes only.

[0038] In the following, preferred embodiments of the compound of the invention are described.

[0039] In a preferred embodiment of the invention, the metal M is selected from molybdenum and tungsten. Particularly preferred, M is molybdenum.

[0040] In the following, preferred embodiments of the benzene ligand are described. In a preferred embodiment of the invention, R1to R6are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; where two adjacent substituents R1to R6may be linked to each other to form a ring. In a particularly preferred embodiment of the invention, R1to R6are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2 or 3 carbon atoms or a branched alkyl group having 3 or 4 carbon atoms. Very particularly preferred groups R1to R6are each independently selected from H, methyl or ethyl.

[0041] It is furthermore preferred that at least three of the substituents R1to R6are H, and particularly preferred at least four of the substituents R1to R6are H.

[0042] It is furthermore preferred that the sum of the number of carbon atoms in the substituents R1to R6is 0, 1 , 2, 3, 4, 5 or 6, more preferred 0, 1 , 2, 3, 4 or 5, more preferred 1 , 2, 3 or 4, more preferred 1 , 2 or 3 and most preferred 1 or 2.

[0043] If the benzene ligand comprises two substituents R1to R6which are different from H, these substituents can be bound in an ortho-position (e.g. R1and R2, etc.), a metaposition (e.g. R1and R3, etc.) or a para-position (e.g. R1and R4, etc.) to each other.

[0044] In the following, preferred embodiments of the fulvene ligand are described. In a preferred embodiment of the invention, R7to R10are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; where two adjacent substituents R7to R10may be linked to each other to form a ring. In a particularly preferred embodiment of the invention, R7to R10are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2 or 3 carbon atoms or a branched alkyl group having 3 or 4 carbon atoms. Very particularly preferred groups R7to R10are each independently selected from H, methyl, ethyl or iso-propyl.

[0045] It is furthermore preferred that at least two of the substituents R7to R10are H, and particularly preferred at least three of the substituents R7to R10are H.

[0046] It is furthermore preferred that the sum of the number of carbon atoms in the substituents R7to R10is 0, 1 , 2, 3, 4 or 5, more preferred 0, 1 , 2, 3 or 4, more preferred 0, 1 , 2 or 3.

[0047] If the fulvene ligand comprises two substituents R7to R10which are different from H, these substituents can be bound in adjacent positions (e.g. R7and R8, R8and R9, etc.) or they can be in non-adjacent positions (e.g. R7and R9, R7and R10, etc.) to each other.

[0048] In a further preferred embodiment of the invention, R11and R12are each independently selected from the group consisting of a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy or thioalkyl group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; furthermore, R11and R12may form a ring with each other. In a particularly preferred embodiment of the invention, R11and R12are each independently selected from the group consisting of a linear alkyl group having 1 , 2 or 3 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms or an alkoxy group having 1 , 2 or 3 carbon atoms; furthermore, R11and R12may form a ring with each other. In a very particularly preferred embodiment of the invention R11and R12are each independently selected from the group consisting of a linear alkyl group having 1 , 2 or 3 carbon atoms or a branched alkyl group having 3 or 4 carbon atoms.

[0049] It is furthermore preferred that at least one of R11and R12comprises at least 2 carbon atoms. Particularly preferred, R11and R12each comprise at least two carbon atoms. In a particularly preferred embodiment, R11and R12are both ethyl or R11is ethyl and R12is iso-propyl or R11and R12are both iso-propyl.

[0050] In a further preferred embodiment, R11and R12are identical to each other. In a further preferred embodiment of the invention, the sum of the number of carbon atoms in the substituents R1to R12is 4, 5, 6, 7, 8 or 9, more preferred 5, 6, 7 or 8 and most preferred 6, 7 or 8.

[0051] It is particularly preferred when the embodiments described above are applied simultaneously. It is therefore preferred when the symbols of formula (1) have the following meanings:

[0052] M is selected from molybdenum and tungsten;

[0053] R1to R6are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; and preferably at least three of R1to R6are H; where two adjacent substituents R1to R6may be linked to each other to form a ring; and preferably the sum of the number of carbon atoms in R1to R6is 0, 1 , 2, 3, 4, 5 or 6;

[0054] R7to R10are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; and preferable at least two of the substituents R7to R10are H; where two adjacent substituents R7to R10may be linked to each other to form a ring; and preferably the sum of the number of carbon atoms in the substituents R7to R10is 0, 1 , 2, 3, 4 or 5;

[0055] R11, R12are each independently selected from the group consisting of a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy or thioalkyl group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each have 1 or 2 carbon atoms; furthermore, R11and R12may form a ring with each other; and preferably at least one of R11and R12comprises at least 2 carbon atoms; and preferably R11and R12are identical to each other; wherein preferably the sum of the number of carbon atoms in the substituents R1to R12is 4, 5, 6, 7, 8 or 9.

[0056] It is particularly preferred when the symbols in formula (1) have the following meanings:

[0057] M is molybdenum;

[0058] R1to R6are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2 or 3 carbon atoms or a branched alkyl group having 3 or 4 carbon atoms; preferably R1to R6are independently H, methyl or ethyl; and preferably at least four of R1to R6are H; and preferably the sum of the number of carbon atoms in R1to R6is 0, 1 , 2, 3, 4 or 5, more preferred 1 , 2, 3 or 4, more preferred 1 , 2 or 3 and most preferred 1 or 2;

[0059] R7to R10are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2 or 3 carbon atoms or a branched alkyl group having 3 or 4 carbon atoms; preferably R7to R10are independently H, methyl, ethyl or iso-propyl; and preferable at least three of the substituents R7to R10are H; and preferably the sum of the number of carbon atoms in the substituents R7to R10is 0, 1 , 2, 3 or 4, more preferred 0, 1 , 2 or 3, and most preferred 0, 1 or 2;

[0060] R11, R12are each independently selected from the group consisting of a linear alkyl group having 1 , 2 or 3 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms or an alkoxy group having 1 , 2 or 3 carbon atoms; furthermore, R11and R12may form a ring with each other; and preferably R11and R12each comprise at least 2 carbon atoms and are preferably selected from ethyl and iso-propyl; and preferably R11and R12are identical to each other; wherein preferably the sum of the number of carbon atoms in the substituents R1to R12is 5, 6, 7 or 8 and more preferred 6, 7 or 8.

[0061] It is most preferred when the symbols in formula (1) have the following meanings:

[0062] M is molybdenum; R1to R6are each independently selected from the group consisting of H, methyl or ethyl; and at least four of R1to R6are H; and the sum of the number of carbon atoms in R1to R6is 1 or 2;

[0063] R7to R10are each independently selected from the group consisting of H, methyl or ethyl; and at least three of the substituents R7to R10are H;

[0064] R11, R12are each independently selected from the group consisting of ethyl and isopropyl; and preferably R11and R12are identical to each other; wherein the sum of the number of carbon atoms in the substituents R1to R12is 6, 7 or

[0065] Examples for compounds of the present invention are shown in the following table where Me = methyl, Et = ethyl, iPr = iso-propyl, tBu = tert-butyl, OMe = methoxy (OCH3), NMe2 = dimethylamino and SMe = thiomethyl (SCH3):

[0066] It is preferable that the compound of formula (1) or the preferred embodiments is essentially free of impurities. This refers in particular to metal impurities, organic byproducts and halogen impurities. The content of each of the impurity metal elements is preferably 10 ppm or less, more preferably 1 ppm or less, and the total content thereof is preferably 50 ppm or less, more preferably 10 ppm or less. The total content of the impurity halogens is preferably 100 ppm or less, more preferably 10 ppm or less, and most preferably 1 ppm or less.

[0067] The compound of formula (1) and the preferred embodiments can be synthesized by reaction of the corresponding bis(arene) metal complex with a fulvene ligand, as shown in the following reaction scheme: where the symbols have the same meanings as defined above. The synthesis is preferably performed in a solvent. Suitable solvents for the ligand exchange reaction are polar or non-polar aprotic solvents, such as THF, dioxane, diethylether, methyl-tert-butylether, dibutylether, hexane, pentane or heptane.

[0068] The temperature for the synthesis process is preferably in the range from room temperature to 150 °C and particularly preferably in the range from 40 to 100 °C.

[0069] The present invention is therefore further directed to a method of manufacturing a compound of formula (1) or the preferred embodiments wherein a bis(arene) chromium, molybdenum or tungsten complex is reacted with a fulvene ligand.

[0070] Method of Use

[0071] The disclosed compounds can be used as precursors (reactants) for the deposition of Group 6 metal-containing films using any chemical vapor deposition process known to those of skill in the art. The precursor for forming a thin film, also referred to as “thin film forming precursor”, comprises the compound according to the present invention and optionally further compounds, depending on the production process to which the precursor is applied. For example, when a thin film containing only chromium, molybdenum or tungsten as a metal is produced, the thin film forming precursor of the present invention is free of metal compounds other than the compound represented by the general formula (1). Meanwhile, when a thin film containing two or more kinds of metals is produced, the thin film forming precursor of the present invention may contain a compound containing a desired metal in addition to the compound represented by the general formula (1). As the evaporation properties of the compound of formula (1) can be adjusted by modification of the substituents of the compound, in particular the substituents on the fulvene ligand, it is also possible to obtain a precursor which can be co-evaporated together with the other precursor. The thin film forming precursor of the present invention may further contain an organic solvent. As described above, the physical properties of the compound represented by the general formula (1) are suitable for serving as the precursor for a CVD method, and hence the thin film forming precursor of the present invention is useful as a CVD precursor. Furthermore, the thin- film forming precursor of the present invention is particularly suitable for an ALD method because the compound represented by the general formula (1) has a selflimiting reaction behavior at the surface, i.e. is not reacting with the adsorbed surface precursor species.

[0072] As used herein, the term “chemical vapor deposition process” (CVD) refers to any process wherein a substrate is exposed to one or more volatile precursors, which react and / or decompose on the substrate surface to produce the desired deposition. As used herein, the term “atomic layer deposition process” (ALD) refers to a self-limiting (e.g., the amount of film material deposited in each reaction cycle is constant), sequential surface chemistry that deposits films of materials onto substrates of varying compositions. Although the precursors, reagents and co-reagents used herein may be sometimes described as “gaseous,” it is understood that the precursors can be either liquid or solid at room temperature and / or at elevated temperature and are transported with or without an inert gas into the reactor via direct vaporization, bubbling or sublimation. In some case, the vaporized precursors can pass through a plasma generator. The term “reactor” as used herein, includes without limitation, the reaction chamber (reaction vessel, deposition chamber).

[0073] Chemical vapor deposition processes in which the disclosed and claimed compounds can be utilized as precursors include, but are not limited to, those used for the manufacture of semiconductor type microelectronic devices, such as ALD, CVD, pulsed CVD, plasma enhanced ALD (PEALD) and / or plasma enhanced CVD (PECVD). Examples of suitable deposition processes for the method disclosed herein include, but are not limited to, cyclic CVD (CCVD), MOCVD (Metal Organic CVD), thermal chemical vapor deposition, plasma enhanced chemical vapor deposition (“PECVD”), high density PECVD, photon assisted CVD, plasma-photon assisted (“PPECVD”), cryogenic chemical vapor deposition, chemical assisted vapor deposition, hot-filament chemical vapor deposition, CVD of a liquid polymer precursor, deposition from supercritical fluids, low energy CVD (LECVD), roll-to-roll ALD, spatial ALD and atmospheric pressure ALD. In certain embodiments, the metal-containing films are deposited via atomic layer deposition (ALD), plasma enhanced ALD (PEALD) or plasma enhanced cyclic CVD (PECCVD) process.

[0074] In one embodiment, the chromium, molybdenum or tungsten containing film is deposited using an ALD process. In another embodiment, the chromium, molybdenum or tungsten containing film is deposited using a CCVD process. In a further embodiment, the chromium, molybdenum or tungsten containing film is deposited using a thermal CVD process.

[0075] Suitable substrates on which the disclosed and claimed precursors can be deposited are not particularly limited and vary depending on the intended final use. For example, the substrate may be chosen from oxides, such as HfC>2 based materials, TiC>2 based materials, ZrC>2 based materials, rare earth oxide-based materials, ternary oxide-based materials, etc., or from nitride-based materials. Other substrates may include solid substrates, such as metal substrates (e.g., Au, Pd, Rh, Ru, W, Al, Ni, Ti, Co, Pt), metal silicide containing substrates (e.g., TiSi2, CoSi2, and NiSi2), metal nitride containing substrates (e.g., TaN, TiN, WN, TaCN, TiCN, TaSiN, and TiSiN), semiconductor materials (e.g., Si, SiGe, GaAs, InP, diamond, GaN, and SiC), insulators (e.g., SiO2, SisN4, SiON, HfO2, Ta2Os, ZrO2, TiO2, AI2O3, and barium strontium titanate), and combinations thereof. Preferred substrates include TiN, Ru and Si type substrates.

[0076] In such deposition methods and processes, usually a co-reactant is used, such as an oxidizing agent. An “oxidizing agent” in the sense of this application is understood to mean a chemical compound which transfers oxygen to the chromium, molybdenum or tungsten containing film. The oxidizing agent is typically introduced in gaseous form. Examples of suitable oxidizing agents include, but are not limited to, oxygen gas, water vapor, ozone, oxygen plasma, or mixtures thereof.

[0077] Further possible co-reactants are reducing agents, such as H2, H2 plasma, hydrazine or aminoboranes, nitrogen-containing co-reactants, such as hydrazine, NH3, N2 or N2 plasma, sulfur-containing co-reactant, such as H2S or elemental sulfur, or peroxides, such as H2O2 or HOOtBu.

[0078] The deposition methods and processes may also involve purge steps, which are usually done by using one or more purge gases. The purge gas, which is used to purge away unconsumed reactants and / or reaction byproducts, is an inert gas that does not react with the precursors and with the formed thin film. Exemplary purge gases include, but are not limited to, argon (Ar), nitrogen (N2), helium (He), neon (Ne), and mixtures thereof. For example, a purge gas, such as Ar, is supplied into the reactor at a flow rate ranging from about 10 to about 2000 seem for about 0.1 to 10000 seconds, thereby purging the unreacted material and any byproduct that may remain in the reactor.

[0079] The deposition methods and processes require that energy is applied to the at least one of the precursors according to the present invention, co-reactants or combination thereof to induce reaction and to form the chromium, molybdenum or tungsten containing film or coating on the substrate. Such energy can be provided by, but not limited to, temperature (thermally induced), plasma, pulsed plasma, helicon plasma, high density plasma, inductively coupled plasma, X-ray, e-beam, photon, remote plasma methods, and combinations thereof. In some processes, a secondary RF frequency source can be used to modify the plasma characteristics at the substrate surface. When utilizing plasma, the plasma-generated process may include a direct plasma-generated process in which plasma is directly generated in the reactor, or alternatively a remote plasma-generated process in which plasma is generated outside of the reactor and supplied into the reactor.

[0080] When utilized in such deposition methods and processes, suitable precursors, such as the compounds of the present invention, may be delivered to the reaction chamber, such as a CVD or ALD reactor, in a variety of ways. A preferred method of delivering the precursors to the reaction chamber is by vaporization of the precursor, e.g. either by vacuum driven thermal vaporization or by active vaporization using a carrier gas. In other instances, a liquid delivery system or a combined liquid delivery and flash vaporization process unit may be employed to enable low volatility materials to be volumetrically delivered, which leads to reproducible transport and deposition without thermal decomposition of the precursor. The precursor compositions described herein can be effectively used as reagents via direct liquid injection (DLI) or via vacuum driven vaporization to provide a vapor stream of these metal precursors into an ALD or CVD reactor. Vacuum driven vaporization is the preferred method of delivery for the precursors according to the present invention.

[0081] When used in these deposition methods and processes, the disclosed and claimed compounds may include hydrocarbon solvents which are particularly desirable due to their ability to be dried to sub-ppm levels of water. Exemplary hydrocarbon solvents that can be used in the precursors include, but are not limited to, toluene, mesitylene, cumene (isopropylbenzene), p-cymene (4-isopropyl toluene), 1 ,3-diisopropylbenzene, octane, dodecane, 1 ,2,4-trimethylcyclohexane, n-butylcyclohexane, and decahydronaphthalene (decalin). The disclosed and claimed compounds can also be stored and used in stainless steel containers. In certain embodiments, the hydrocarbon solvent is a high boiling point solvent or has a boiling point of 100 °C or greater. However, a solvent is not necessarily used. The disclosed and claimed compounds can also be mixed with other suitable metal compounds, which can be utilized as precursors, and the mixture used to deliver both metals simultaneously for the growth of a binary metalcontaining films.

[0082] A flow of argon and / or other gas may be employed as a carrier gas to help deliver a vapor containing at least one of the disclosed and claimed precursors to the reaction chamber during the precursor pulsing. When delivering the precursors, the reaction chamber process pressure is between 1 and 50 torr, preferably between 5 and 20 torr.

[0083] Substrate temperature can be an important process variable in the deposition of high- quality chromium, molybdenum or tungsten containing films. Typical substrate temperatures range from about 100 °C to about 550 °C. Higher temperatures can promote higher film growth rates, but might result in bulk CVD rather than ALD. Furthermore, there is the risk at higher substrate temperatures that the precursor desorbs from the substrate, thus resulting in lower growth rates. If the substrate temperature is not high enough, the temperature might be too low for a sufficient reaction of the precursor with the surface, which also results in lower growth rates, and / or the precursor might condense on the surface resulting in increasing growth rates.

[0084] In view of the forgoing, those skilled in the art will recognize that the disclosed and claimed subject matter further includes the use of the disclosed and claimed compounds as precursors in chemical vapor deposition (CVD) processes as follows.

[0085] In one embodiment, the disclosed and claimed subject matter includes a method for forming a chromium, molybdenum or tungsten containing film on at least one surface of a substrate that includes the steps of:

[0086] (a) providing the at least one surface of the substrate in a reaction vessel; and

[0087] (b) forming a chromium, molybdenum or tungsten containing film on the at least one surface by a deposition process selected from a chemical vapor deposition (CVD) process and an atomic layer deposition (ALD) process using at least one compound of formula (1) or the preferred embodiments as precursor for the deposition process.

[0088] In a further aspect of this embodiment, the method includes introducing at least one coreactant into the reaction vessel. A co-reactant is a reactant which is used in addition to the precursor of the present invention for the deposition of the chromium, molybdenum or tungsten containing film. In a further aspect of this embodiment, the method includes introducing at least one co-reactant into the reaction vessel where the at least one coreactant is selected from the group of water, oxygen (O2), oxygen plasma, ozone (O3), NO, N2O, NO2, CO, CO2 and combinations thereof. These co-reactants are typically used for forming a metal oxide thin film. In another aspect of this embodiment, the method includes introducing at least one co-reactant into the reaction vessel where the at least one co-reactant is selected from the group of ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, nitrogen, nitrogen / hydrogen, ammonia plasma, nitrogen plasma, nitrogen / hydrogen plasma, and combinations thereof. These coreactants are typically used for forming a metal nitride thin film, but ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, ammonia plasma, and combinations thereof, might also be used for forming a metallic film. In another aspect of this embodiment, the method includes introducing at least one co-reactant into the reaction vessel where the at least one co-reactant is selected from the group of hydrogen, hydrogen plasma, a mixture of hydrogen and helium, a mixture of hydrogen and argon, hydrogen / helium plasma, hydrogen / argon plasma, boron-containing compounds, silicon-containing compounds and combinations thereof. These co-reactants are typically used for forming metallic film, i.e. formation of the elemental metal.

[0089] In one embodiment, the disclosed and claimed subject matter includes a method of forming a chromium, molybdenum or tungsten containing film via an atomic layer deposition (ALD) process or ALD-like process that includes the steps of:

[0090] (a) providing a substrate in a reaction vessel;

[0091] (b) introducing into the reaction vessel one or more of the compounds of formula (1) or the preferred embodiments as precursor;

[0092] (c) a purging step, in particular purging the reaction vessel with a first purge gas;

[0093] (d) introducing into the reaction vessel a co-reactant;

[0094] (e) a purging step, in particular purging the reaction vessel with a second purge gas;

[0095] (f) sequentially repeating steps (b) through (e) until a desired thickness of the chromium, molybdenum or tungsten containing film is obtained.

[0096] Depending on the desired composition of the produced chromium, molybdenum or tungsten containing thin film, the steps (b), (c), (d) and (e) may also be repeated with a second co-reactant in step (d) and optionally a third or further co-reactant and a purging step with the third purge gas and optionally a fourth or further purge gases.

[0097] Furthermore, it is possible in step (b) to introduce two or more precursors, wherein at least one precursor is a compound of formula (1) or the preferred embodiments. These two or more precursors may be introduced as a mixture from the same container or may be introduced from different containers.

[0098] Furthermore, it is possible in step (d) to introduce two or more co-reactants. These two or more co-reactants may be introduced as a mixture from the same source vessel or may be introduced from different containers.

[0099] In a further aspect of this embodiment, the co-reactant is one or more of an oxygencontaining co-reactant selected from water, O2, oxygen plasma, O3, NO, N2O, NO2, CO, CO2 and combinations thereof. In another aspect of this embodiment, the co-reactant is one or more of a nitrogen-containing co-reactant selected from ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, nitrogen, nitrogen / hydrogen, ammonia plasma, nitrogen plasma, nitrogen / hydrogen plasma and mixture thereof. In another aspect of this embodiment, the co-reactant is selected from hydrogen, hydrogen plasma, a mixture of hydrogen and helium, a mixture of hydrogen and argon, hydrogen / helium plasma, hydrogen / argon plasma, boron-containing compounds, silicon-containing compounds and combinations thereof. In a further aspect of this embodiment, the first and second purge gases are each independently selected one or more of argon, nitrogen, helium, neon, and combinations thereof. Additionally or alternatively, vacuum may be applied for one or more purging steps. In a further aspect of this embodiment, the method further includes applying energy to at least one of the precursor, the co-reactant, the substrate, and combinations thereof, wherein the energy is one or more of thermal, plasma, pulsed plasma, helicon plasma, high density plasma, inductively coupled plasma, capacitively coupled plasma, X-ray, e-beam, photon, remote plasma methods and combinations thereof. In a preferred aspect of this embodiment, step (b) of the method includes introducing into the reaction vessel the precursor using thermal energy and vacuum. In a further aspect of this embodiment, step (b) of the method further includes introducing into the reaction vessel the precursor using a stream of carrier gas to deliver a vapor of the precursor into the reaction vessel. In a further aspect of this embodiment, step (b) of the method further includes use of a solvent medium comprising one or more of toluene, mesitylene, isopropylbenzene, 4-isopropyl toluene, 1,3-diisopropylbenzene, octane, dodecane, 1,2,4-trimethylcyclohexane, n-butylcyclohexane, and decahydronaphthalene and combinations thereof.

[0100] The shape of the substrate is not particularly limited and can be, for example, a plate shape, a spherical shape, a fibrous shape, or a scaly shape. The surface of the substrate may be planar, or may have a three-dimensional structure such as a trench structure.

[0101] In addition, examples of the above-mentioned production conditions include a reaction temperature (substrate temperature), a reaction pressure, and a deposition rate. The reaction temperature is preferably from room temperature to 500 °C, more preferably from 100 °C to 300 °C. In addition, the reaction pressure is preferably from 10 Pa to an atmospheric pressure in the case of the thermal CVD or the optical CVD, and is preferably from 10 Pa to 2,000 Pa in the case of using plasma. For ALD, the pressure of a system (in the film formation chamber) when this step is performed is preferably from 1 Pa to 10,000 Pa, more preferably from 10 Pa to 1 ,000 Pa.

[0102] In addition, the deposition rate may be controlled by the supply conditions (vaporization temperature and vaporization pressure) of the precursor, the reaction temperature, and the reaction pressure. When the deposition rate is large, the characteristics of a thin- film to be obtained may deteriorate. When the deposition rate is small, a problem may occur in productivity. Accordingly, for CVD processes, the deposition rate is preferably from 0.01 nm / min to 100 nm / min, more preferably from 1 nm / min to 50 nm / min. In addition, in the case of the ALD method, the deposition rate is controlled by the number of cycles so that a desired film thickness may be obtained. In an ALD process, typical deposition rates are from 0.01 nm / cycle to 0.2 nm / cycle, more typically from 0.05 nm / cycle to 1.3 nm / cycle. Further, as the above-mentioned production conditions, there are given a temperature and a pressure when the thin-film forming precursor is vaporized to obtain a precursor gas. The step of vaporizing the thin-film forming precursor to obtain a precursor gas may be performed in the precursor vessel or in the vaporization chamber. In any case, it is preferred that the thin-film forming precursor of the present invention be evaporated at a temperature between 0 °C and 150 °C. In addition, when the thin-film forming precursor is vaporized to obtain a precursor gas in the precursor vessel or in the vaporization chamber, the pressure in the precursor vessel and the pressure in the vaporization chamber are each preferably from 1 Pa to 10,000 Pa.

[0103] In addition, in the method of producing a thin-film of the present invention, after the thin-film deposition, annealing treatment may be performed under an inert atmosphere, an oxidizing atmosphere, or a reducing atmosphere in order to obtain more satisfactory electrical characteristics. The temperature for annealing is from 200 °C to 1 ,000 °C, preferably from 250 °C to 500 °C.

[0104] Brief description of the drawings

[0105] Fig. 1 shows the TGA curves for the compounds of Examples 1 to 5 according to the invention.

[0106] Fig. 2 shows initial deposition data of compound (3) (Example 3).

[0107] Examples

[0108] Reference will now be made to more specific embodiments of the present disclosure and experimental results that provide support for such embodiments. The examples are given below to more fully illustrate the disclosed subject matter and should not be construed as limiting the disclosed subject matter in any way.

[0109] It will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed subject matter and specific examples provided herein without departing from the spirit or scope of the disclosed subject matter. Thus, it is intended that the disclosed subject matter, including the descriptions provided by the following examples, covers the modifications and variations of the disclosed subject matter that come within the scope of any claims and their equivalents.

[0110] General synthesis procedure:

[0111] A solution of Mo(arene)2 (1 eq.) in THF (70 eq.) is treated with the respective fulvene (1.2 eq.). The reaction mixture is stirred at 60 °C until the ligand exchange is complete (1H NMR monitoring). During this time, the reaction mixture turns dark purple. The solvent and the excess of fulvene are removed in vacuum. The dark purple residue can be purified via sublimation or distillation.

[0112] Using the above-described general procedure, the following compounds (1) to (6) were synthesized. The reaction time was 5 days at 60 °C. Compound (1) was purified by sublimation, and compounds (2) to (6) were purified by distillation. In the following, m- Me2-Ph refers to meta-xylene and Me-Ph refers to toluene.

[0113] Example 1 : Synthesis of Mo(m-Me2-Ph)(Me2-fulv) (1)

[0114] Compound (1) was synthesized by applying the above mentioned synthesis procedure using Mo(m-Me2-Ph)2 and 6,6-dimethylfulvene (Me2-fulv). The product was isolated as a dark purple solid after sublimation. Yield: 72 %.

[0115] 1H NMR (500 MHz, C6D6) 5 = 4.83 (t,3JHH = 2.0 Hz, CH-fulv, 2 H), 4.57 (m,3JHH = 2.0 Hz, CH-fulv, 2 H), 3.99 (d,3JHH = 5.4 Hz, CH-xylene, 2 H), 3.68 (s, CH-xylene, 1 H), 3.66 (t,3JHH = 5.4 Hz, CH-xylene), 1.82 (s, CH3-xylene, 6 H), 1.70 (s, CH3-fulv, 6 H) ppm.

[0116] Example 2: Synthesis of Mo(m-Me2-Ph)(Et2-fulv) (2)

[0117] Compound (2) was synthesized by applying the above mentioned synthesis procedure and 6,6-diethylfulvene (Et2-fulv). The product was isolated as a dark purple liquid after distillation. Upon storing over several days at room temperature the product solidified. Yield: 72 %.

[0118] 1H NMR (500 MHz, C6D6) 5 = 4.79 (t,3JHH = 2.0 Hz, CH-fulv, 2 H), 4.53 (m, CH-fulv, 2 H), 4.16 (d,3JHH = 5.4 Hz, CH-xylene, 2 H), 3.96 (t,3JHH = 5.4 Hz, CH-xylene, 1 H), 3.49 (s, CH-xylene, 1 H), 2.26 (m, CH2-CH3, 2 H), 1.83 (s, CH3-xylene, 6 H), 1.80 (m, CH2-CH3, 2 H), 1.10 (t,3JHH = 7.2 Hz, CH2-CH3, 6 H) ppm.

[0119] Example 3: Synthesis of Mo(m-Me2-Ph)(Et2-Me-fulv) (3)

[0120] Compound (3) was synthesized by applying the above mentioned synthesis procedure using Mo(m-Me2-Ph)2 and 6,6-diethyl-3-methylfulvene (Et2-Me-fulv). The product was isolated as a dark purple liquid after distillation. Yield: 83 %.1H NMR (500 MHz, C6D6) 5 = 4.72 (t,4JHH = 1.7 Hz, CH-fulv, 1 H), 4.52 (m, CH-fulv, 2 H), 4.08 (d,3JHH = 5.4 Hz, CH-xylene, 1 H), 4.04 (d,3JHH = 5.4 Hz, CH-xylene, 1 H), 3.91 (t,3JHH = 5.4 Hz, CH-xylene, 1 H), 3.43 (s, CH-xylene, 1 H), 2.28 (m, C / 72-CH3, 2 H), 1.85 (s, CH3-xylene, 3 H), 1.82 (s, CH3-xylene, 3 H), 1.77 (m, CH2-CH3, 2 H), 1.67 (s, CH3-fulv, 6 H), 1.11 (td,3JHH = 7.2 Hz,5JHH = 2.4 Hz CH2-CH3, 6 H) ppm.

[0121] Example 4: Synthesis of Mo(m-Me2-Ph)(Et2-iPr-fulv) (4)

[0122] Compound (4) was synthesized by applying the above mentioned synthesis procedure using Mo(m-Me2-Ph)2and 6,6-diethyl-3-isopropylfulvene (Et2-iPr-fulv). The product was isolated as a dark purple liquid after distillation. Yield: 79 %.

[0123] 1H NMR (500 MHz, C6D6) 5 = 4.81 (s, CH-fulv, 1 H), 4.58 (s, CH-fulv, 1 H), 4.52 (s, CH- fulv, 1 H), 4.14 (d,3JHH = 5.4 Hz, CH-xylene, 1 H), 3.99 (d,3JHH = 5.4 Hz, CH-xylene, 1 H), 3.89 (t,3JHH = 5.4 Hz, CH-xylene, 1 H), 3.58 (s, CH-xylene, 1 H), 2.29 (m, CH2-CH3, 2 H), 2.20 (m, / 7CMe2, 1 H), 1.90 (s, CH3-xylene, 3 H), 1.84 (s, CH3-xylene, 3 H), 1.77 (m, CH2-CH3, 2 H), 1.11 (m, CH2-CH3, 6 H), 1.04 (m, H(CH3)2, 6 H) ppm.

[0124] Example 5: Synthesis of Mo(Me-Ph)(Et2-iPr-fulv) (5)

[0125] Compound (5) was synthesized by applying the above mentioned synthesis procedure using Mo(Me-Ph)2and 6,6-diethyl-3-isopropylfulvene (Et2-iPr-fulv). The product was isolated as a dark purple liquid after distillation. Yield: 75 %.

[0126] 1H NMR (500 MHz, C6D6) 5 = 4.97 (m, CH-fulv, 1 H), 4.60 (s, CH-fulv, 1 H), 4.52 (m, CH-fulv, 1 H), 4.18 (t,3JHH = 5.4 Hz, CH-xylene, 1 H), 3.98 (t,3JHH = 5.4 Hz, CH-xylene, 1 H), 3.92 (d,3JHH = 5.4 Hz, CH-xylene, 1 H), 3.85 (t,3JHH = 5.4 Hz, CH-xylene, 1 H) 3.70 (d,3JHH = 5.4 Hz, CH-xylene, 1 H), 2.31 (m, / 7CMe2, 1 H), 2.22 (m, CH2-CH3, 2 H), 1.86 (s, CH3-xylene, 3 H), 1.77 (m, CH2-CH3, 2 H), 1.11 (q,3JHH = 7.2 Hz, CH2-CH3, 6 H), 1.00 (d,3JHH = 6.8 Hz H(CH3)2, 6 H) ppm.

[0127] Example 6: Synthesis of Mo(m-Me2-Ph)(Me2-Me-fulv) (6) (mixture of two isomers)

[0128] Compound (6) was synthesized by applying above mentioned synthesis procedure using Mo(m-Me2-Ph)2and 6,6-dimethyl-3-methylfulvene (Me2-Me-fulv). It should be noted here that the used fulvene was a mixture of two isomers 6,6-dimethyl-3- methylfulvene and 6,6-dimethyl-2-methylfulvene in a ratio of 90:10. The product was isolated as a dark purple liquid after distillation. Yield: 77 %.

[0129] This compound was synthesized to investigate the impact of an additional methyl group on the fulvene ring, compared to compound (1), on its thermal stability. The resulting TGA curve of this compound (Tso% = 233 °C; residual mass = 27%) was similar to that of compound (1), indicating a similar decomposition temperature. This observation shows that the alkyl substitution at the fulvene ring has less influence on the thermal stability compared to the alkyl substitution at the exocyclic double bond.

[0130] Analysis by TGA

[0131] TGA curves were determined for the compounds of examples 1 to 5. The samples were heated with a heating ramp of 10 K min-1at an Ar flow of 20 ml min-1. The sample mass of each compound was 10 mg for the TGA experiment. The TGA curves are shown in Figure 1.

[0132] Discussion of results

[0133] The six compounds (1) to (6) were successfully isolated in high yields by stirring the corresponding Mo(arene)2with the respective fulvene in THF for 5 days at 60 °C. Thermal characterization was conducted using thermogravimetric analysis (TGA) on all compounds (Figure 1).The evaporation temperature (Tso%, i.e. temperature for 50 % mass loss) is compared in Table 1. Compound (1) exhibits the lowest T50% in this series and undergoes a two-step evaporation process, leaving a residual mass of 30%, which suggests some thermal decomposition. In contrast, compounds (2) to (5) demonstrate the ability to evaporate with no decomposition, as evidenced by a residual mass of less than 4%. Among these, compounds (4) and (5) show the lowest volatility, but also possess the highest mass within the series.

[0134] From these thermal data of compounds (1) to (6), it can be concluded that the alkyl groups at the exocyclic double bond have a significant impact on the thermal stability. Furthermore, introducing a non-symmetric fulvene ligand lowers the melting point below room temperature.

[0135] Table 1

[0136] Discussion of deposition data

[0137] Initially, the thermal decomposition of the compound (3) (Example 3) over various substrates (Si, Cu, and HTiN) was tested. No decomposition was observed on any of the substrates up to 500 °C, indicating high thermal stability (Fig. 2). Subsequently, the plasma reactivity towards NH3was examined (Fig. 2). Plasma treatments with NH3at elevated temperatures (400 °C) exhibited reactivity of the compound.

Claims

Claims1. Compound of formula (1):Formula (1) wherein the symbols have the following meanings:M is chromium, molybdenum or tungsten;R1, R2, R3, R4, R5, R6, R7, R8, R9, R10are each independently selected from the group consisting of H, D, F, Cl, Br, I, a linear alkyl group having 1 to 6 carbon atoms, a branched or cyclic alkyl group having 3 to 6 carbon atoms or an alkoxy, thioalkyl or dialkylamino group, wherein the alkyl group of the alkoxy, thioalkyl or dialkylamino group is independently selected from a linear alkyl group having 1 to 6 carbon atoms or a branched or cyclic alkyl group having 3 to 6 carbon atoms; where two adjacent substituents R1to R6may be linked to each other to form a ring and / or where where two adjacent substituents R7to R10may linked to each other to form a ring and / or where one of the substituents R1to R6and one of the substituents R7to R10may be linked to each other;R11, R12are each independently a H, D, a linear alkyl group having 1 to 6 carbon atoms, a branched or cyclic alkyl group having 3 to 6 carbon atom or an alkoxy, thioalkyl or dialkylamino group, wherein the alkyl group of the alkoxy, thioalkyl or dialkylamino group is independently selected from a linear alkyl group having 1 to 6 carbon atoms or a branched or cyclic alkyl group having 3 to 6 carbon atoms; where R11and R12may be linked to each other to form a ring; the following compounds are excluded from the invention:

2. Compound according to claim 1 , characterized in that R1to R6are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; where two adjacent substituents R1to R6may be linked to each other to form a ring.

3. Compound according to claim 1 or 2, characterized in that at least three of the substituents R1to R6are H and / or that the sum of the number of carbon atoms in the substituents R1to R6is 0, 1 , 2, 3, 4, 5 or 6.

4. Compound according to one or more of claims 1 to 3, characterized in that R7to R10are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; where two adjacent substituents R7to R10may be linked to each other to form a ring.

5. Compound according to one or more of claims 1 to 4, characterized in that at least two of the substituents R7to R10are H and / or that the sum of the number of carbon atoms in the substituents R7to R10is 0, 1 , 2, 3, 4 or 5.

6. Compound according to one or more of claims 1 to 5, characterized in that R11and R12are each independently selected from the group consisting of a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy or thioalkyl group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; furthermore, R11and R12may form a ring with each other.

7. Compound according to one or more of claims 1 to 6, characterized in that one of R11and R12comprises at least 2 carbon atoms or that R11and R12each comprise at least 2 carbon atoms.

8. Compound according to one or more of claims 1 to 7, characterized in that the sum of the number of carbon atoms in the substituents R1to R12is 4, 5, 6, 7, 8 or 9.

9. Compound according to one or more of claims 1 to 8, wherein the symbols have the following meanings:M is selected from molybdenum and tungsten;R1to R6are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; where two adjacent substituents R1to R6may be linked to each other to form a ring; and at least three of R1to R6are H; and the sum of the number of carbon atoms in R1to R6is 0, 1 , 2, 3, 4, 5 or 6;R7to R10are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each independently have 1 or 2 carbon atoms; where two adjacent substituents R7to R10may be linked to each other to form a ring; and at least two of the substituents R7to R10are H; and the sum of the number of carbon atoms in the substituents R7to R10is 0, 1 , 2, 3, 4 or 5;R11, R12are each independently selected from the group consisting of a linear alkyl group having 1 , 2, 3 or 4 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms, an alkoxy or thioalkyl group having 1 , 2 or 3 carbon atoms or a dialkylamino group wherein the alkyl groups each have 1 or 2 carbon atoms; furthermore, R11and R12may form a ring with each other.

10. Compound according to one or more of claims 1 to 9, wherein the symbols have the following meanings:M is molybdenum;R1to R6are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2 or 3 carbon atoms or a branched alkyl group having 3 or 4 carbon atoms; and at least four of R1to R6are H; and the sum of the number of carbon atoms in R1to R6is 0, 1 , 2, 3, 4 or 5;R7to R10are each independently selected from the group consisting of H, a linear alkyl group having 1 , 2 or 3 carbon atoms or a branched alkyl group having 3 or 4 carbon atoms; and at least three of the substituents R7to R10are H; and the sum of the number of carbon atoms in the substituents R7to R10is 0, 1 , 2, 3 or 4;R11, R12are each independently selected from the group consisting of a linear alkyl group having 2 or 3 carbon atoms, a branched alkyl group having 3 or 4 carbon atoms or an alkoxy group having 1 , 2 or 3 carbon atoms; furthermore, R11and R12may form a ring with each other.

11. Compound according to one or more of claims 1 to 10, wherein the symbols have the following meanings:M is molybdenum;R1to R6are each independently selected from the group consisting of H, methyl or ethyl; and at least four of R1to R6are H; and the sum of the number of carbon atoms in R1to R6is 1 or 2;R7to R10are each independently selected from the group consisting of H, methyl, ethyl or iso-propyl; and at least three of the substituents R7to R10are H;R11, R12are each independently selected from the group consisting of ethyl and iso-propyl; and preferably R11and R12are identical to each other; wherein the sum of the number of carbon atoms in the substituents R1to R12is 6, 7 or 8.

12. Method of manufacturing a compound according to one or more of claim 1 to 11 , characterized in that a bis(arene) complex of chromium, molybdenum or tungstenis reacted with a fulvene ligand according to the following formula:where the symbols have the meanings as described in claim 1.

13. Use of a compound according to one or more of claim 1 to 11 for the deposition of a chromium, molybdenum or tungsten containing film.

14. Method for forming a chromium, molybdenum or tungsten containing film on at least one surface of a substrate, comprising the steps:(a) providing at least one surface of the substrate in a reaction vessel; and(b) forming a chromium, molybdenum or tungsten containing film on the at least one surface by a deposition process selected from a chemical vapor deposition (CVD) process and an atomic layer deposition (ALD) process using at least one compound according to one or more of claim 1 to 11 as precursor of a chromium, molybdenum or tungsten source compound for the deposition process.

15. Method according to claim 14, further comprising introducing into the reaction vessel at least one co-reactant, selected from the group of water, oxygen, oxygen plasma, ozone, NO, N2O, NO2, CO, CO2, ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, nitrogen, nitrogen / hydrogen, ammonia plasma, nitrogen plasma, nitrogen / hydrogen plasma, hydrogen, hydrogen plasma, a mixture of hydrogen and helium, a mixture of hydrogen and argon, hydrogen / helium plasma, hydrogen / argon plasma, boron-containing compounds, silicon-containing compounds and combinations thereof.

16. Method for forming a chromium, molybdenum or tungsten containing film via an atomic layer deposition (ALD) process or ALD-like process, the method comprising the steps of:(a) providing a substrate in a reaction vessel;(b) introducing into the reaction vessel one or more compounds according to one or more of claims 1 to 11 as precursor;(c) a purging step, in particular purging the reaction vessel with a first purge gas;(d) introducing into the reaction vessel a co-reactant;(e) a purging step, in particular purging the reaction vessel with a second purge gas;(f) sequentially repeating steps (b) through (e) until a desired thickness of the chromium, molybdenum or tungsten containing film is obtained.

17. Method according to claim 16 characterized in that at least one co-reactant in step (d) is selected from water, O2, O3, NO, N2O, NO2, CO, CO2, ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, nitrogen, nitrogen / hydrogen, hydrogen, a mixture of hydrogen and helium, a mixture of hydrogen and argon, hydrogen / helium plasma, boron-containing compounds, silicon-containing compounds and combinations thereof or a plasma of these co-reactants.

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