Group VI Precursor Compounds

Abstract

The present invention provides a convenient method for preparing various Group VI precursor compounds that can be used to vapor deposit such Group VI metals onto solid substrates, especially microelectronic semiconductor device substrates. The method provides an efficient means of obtaining such volatile materials, which can then serve as a source of molybdenum, chromium or tungsten containing materials to be deposited on the substrate. In addition, the present invention provides methods for vapor depositing the compounds onto microelectronic device substrates.

Description

Technical Field

[0001] The present invention relates to certain precursors for vapor deposition of certain Group VI containing materials and methods for preparing the same. Background Art

[0002] Due to their extremely high melting points, low coefficients of thermal expansion, low resistivity, and high thermal conductivity, Group VI metals (e.g., molybdenum, chromium, and tungsten) are increasingly used in the fabrication of semiconductor devices, including use in diffusion barriers, electrodes, photomasks, power electronic substrates, low resistivity gates, flat panel displays, and interconnects.

[0003] Such availability has prompted efforts to achieve deposition of molybdenum, chromium, and tungsten films for such applications characterized by high conformality of the deposited films and high deposition rates to accommodate efficient high-volume manufacturing operations. This, in turn, has enabled efforts to develop improved molybdenum and tungsten source reagents for vapor deposition operations and improved process parameters utilizing the reagents. Summary of the invention

[0004] The present invention provides a convenient method for preparing various Group VI precursor compounds that can be used to vapor deposit certain Group VI metals onto solid substrates, especially microelectronic semiconductor device substrates. The method provides an efficient means of obtaining and isolating the volatile solid or liquid materials, which can then serve as a source of molybdenum-containing, chromium-containing or tungsten-containing materials to be deposited on the substrates. In addition, the present invention provides methods for vapor depositing the compounds onto microelectronic device substrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 It is a three-dimensional solid-state crystal structure depiction of MoO2Cl2(CH3CN)2.

[0006] Figure 2 It is a three-dimensional solid-state crystal structure depiction of WO2Cl2(CH3CN)2.

[0007] Figure 3 The deposition rate of molybdenum on titanium nitride substrate using MoO2Cl2 (dimethoxyethane) as precursor ( / cycle) versus substrate temperature (°C).

[0008] Figure 4 XRF carbon (for X-ray fluorescence analysis of carbon) (μgm / cm) on titanium nitride substrate using MoO2Cl2(dimethoxyethane)2 as precursor 2 / Mo) versus substrate temperature (°C). Therefore, Figure 3 and 4 Schematic illustration of process parameters for preferential deposition of Mo relative to MoC.

[0009] Figure 5 It is a three-dimensional solid-state crystal structure drawing of MoO2Cl2(tetrahydrofuran)2. DETAILED DESCRIPTION

[0010] In a first aspect, the present invention provides a method for preparing a compound of formula (I)

[0011]

[0012] wherein M is selected from molybdenum, chromium and tungsten, X is selected from fluorine, chlorine, bromine and iodine, and each L1 and L2 are the same or different and constitute:

[0013] (i) a monodentate hydrocarbon-based ligand coordinated to M, or

[0014] (ii) together form a bidentate hydrocarbon ligand coordinated to M;

[0015] The method comprises:

[0016] (A) The following compound

[0017]

[0018] contacting with: (a) water containing from about 0.1% (w / w) to about 48% (w / w) of a compound of formula HX, and (b) a compound of formula L1 and / or L2; subsequently

[0019] (B) isolating the compound of formula (I) into a solid or liquid.

[0020] As used herein, the term "hydrocarbyl" refers to a C2-C4 hydrocarbon group comprising carbon and hydrogen atoms and optionally containing at least one nitrogen, sulfur or oxygen atom. 16 The hydrocarbon group may include straight-chain or branched saturated, unsaturated and polyunsaturated alkylene and cycloalkylene groups and may be substituted, for example, by one to five groups selected from the group consisting of C1-C6 alkoxy, carboxyl, nitro, amino, C2-C6 aminocarbonyl, C2-C6 amide, cyano, C2-C7-alkoxycarbonyl, C2-C7-alkanoyloxy, hydroxyl, aryl, heteroaryl, thiol, thioether, C2-C6 10 Dialkylamino, C3-C 15 The terms "C1-C6 alkoxy", "C2-C7-alkoxycarbonyl" and "C2-C7-alkanoyloxy" are used to denote the radicals corresponding to the structures --OR 3 、--CO2R 3 and --OCOR 3 A group in which R 3 is C1-C6 alkyl or substituted C1-C6 alkyl.16 Aminocarbonyl" and "C2-C 16 "Amide" is used to represent the structure corresponding to NHCOR 4 、--CONHR 4 A group in which R 4 As mentioned above, L1 and L2 comprise the hydrocarbon group and contain at least one nitrogen, sulfur or oxygen atom.

[0021] L1 and L2 are independently selected and represent monodentate ligands or form bidentate ligands together. In general, L1 and L2 comprise a hydrocarbon group having at least one oxygen, sulfur or nitrogen atom. The ligand may be selected from, for example, tert-butyl nitrile, toluene, tetrahydrofuran and acetonitrile, and the group may be optionally substituted with one or more groups selected from the following: halogen, cyano, nitro, C1-C6 alkyl, C1-C6 alkoxy, tetrahydrofuran, C1-C6 alkoxycarbonyl and phenyl. Other examples include 1,2-dimethoxyethane; 1,2-diethoxyethane; 1,2-dimethoxypropane; N,N-dimethylacetamide; N,N-dimethylformamide; N,N-dimethylcyanoacetamide; diamines and triamines, such as N,N,N',N'-tetramethylethylenediamine, ethylenediamine, hexylenediamine, diethylenetriamine and diethylenetriamine; dimethyl sulfoxide; and diols, such as ethylene glycol, propylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol and 1,6-hexanediol.

[0022] Step (B) isolating the compound of formula (I) can be implemented by extracting the compound from the aqueous reaction mixture using a water-immiscible solvent, followed by evaporation of the solvent or crystallization. Alternatively, a water-soluble solvent such as an alcohol (e.g., ethanol) can be added to the aqueous solution to induce precipitation of the desired compound of formula (I). If desired, the solid compound of formula (I) can be purified by crystallization and / or vacuum sublimation.

[0023] It will be appreciated that the structures of the compounds of the present invention depicted above are drawn in a two-dimensional format and do not necessarily represent their three-dimensional orientation.

[0024] In addition, once formed, the compound of formula (I) can be reacted with additional / different compounds of formula L1 and / or L2 to form different compounds of formula (I) via a displacement reaction. Therefore, in another embodiment, the present invention provides the above method, which further comprises the step of contacting the compound of formula (I) with a compound selected from the following: tert-butyl nitrile, toluene, tetrahydrofuran and acetonitrile, and the group is optionally substituted with one or more groups selected from halo, cyano, nitro, C1-C6 alkyl, C1-C6 alkoxy, tetrahydrofuran, C1-C6 alkoxycarbonyl and phenyl; 1,2-dimethoxyethane; 1,2-diethoxyethane; 1,2-dimethoxypropane; N,N-dimethylacetamide; N,N-dimethylformamide; N,N-dimethylcyanoacetamide; N,N,N',N'-tetramethylethylenediamine, ethylenediamine, hexamethylenediamine, diethylenetriamine (diethylene triamine and diethylenetriamine; dimethyl sulfoxide; and ethylene glycol, propylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol and 1,6-hexanediol,

[0025] To obtain compounds of formula (I) having different ligands of formula L1 and / or L2.

[0026] In other embodiments, the present invention provides a compound of formula (I)

[0027]

[0028] wherein M is selected from molybdenum, chromium and tungsten, X is selected from fluorine, chlorine, bromine and iodine, and each L1 and L2 are the same or different and constitute:

[0029] (i) a monodentate hydrocarbon-based ligand coordinated to M, or

[0030] (ii) together form a bidentate hydrocarbon ligand coordinated to M;

[0031] It is in solid or liquid form. In certain embodiments, the compound of formula (I) has less than about 3% impurities by weight. In other embodiments, the compound of formula (I) has less than 1% impurities by weight. In other embodiments, the compound of formula (I) is isolated in crystalline form. Specific examples of the crystalline form of the compound of formula (I) include MoO2Cl2(CH3CN)2 and WO2Cl2(CH3CN)2 and MoO2Cl2(tetrahydrofuran)2. In another embodiment, the present invention provides a compound of formula MoO2Cl2(CH3CN)2, in crystalline form and having Figure 1 In another embodiment, the present invention provides a compound having the formula WO2Cl2(CH3CN)2, in crystalline form and having the following Figure 2In another embodiment, the present invention provides a compound having the formula MoO2Cl2(tetrahydrofuran)2, in crystalline form and having the following Figure 5 The compounds with the x-ray crystal structures shown in . These crystalline forms are further characterized in the following experimental section.

[0032] In another embodiment, the present invention provides a compound having the formula MoO2Cl2(CH3CN)2 and having an orthorhombic system and a unit cell size of about:

[0033] α=90°

[0034] β=90°

[0035] γ=90°.

[0036] In another embodiment, the present invention provides a compound having the formula WO2Cl2(CH3CN)2 and having an orthorhombic system and a unit cell size of about:

[0037] α=90°

[0038] β=90°

[0039] γ=90°.

[0040] In another embodiment, the present invention provides a compound having the formula MoO2Cl2(tetrahydrofuran)2 and having an orthorhombic system and a unit cell size of about:

[0041] α=90°

[0042] β=90°

[0043] γ=90°.

[0044] As used herein, the term "unit cell" refers to the smallest and simplest volume element of a crystal that completely represents a unit of the crystal pattern. The dimensions of a unit cell are defined by six values: dimensions a, b, and c and angles α, β, and γ. A crystal is an effective packed array of many unit cells.

[0045] As used herein, the term "orthorhombic unit cell" refers to a unit cell where a≠b≠c; α=β=γ=90°.

[0046] As used herein, "crystalline lattice" refers to the array of points defined by the vertices of stacked unit cells, as determined by single crystal x-ray diffraction analysis.

[0047] As used herein, "space group" refers to the symmetry of a unit cell. In a space group name (eg, C2), a capital letter indicates the lattice type, and the other symbols represent symmetry operations that can be performed on the unit cell without changing its appearance.

[0048] In the method of the present invention, suitable water-immiscible solvents include dichloromethane, ethyl acetate, diethyl ether, toluene, benzene, pentane and the like.

[0049] In one embodiment, the method is performed at an elevated temperature (eg, about 20°C to about 100°C).

[0050] The compounds of formula (I) can also be prepared by using starting materials of the following formula:

[0051]

[0052] That is, a compound of the general formula A2MO4, wherein M is selected from chromium, molybdenum or tungsten, and A is selected from Group I and Group II metals or ammonium cations. Examples of the cations include Li + 、Na + , K + NH4 + , alkylammonium compounds, etc. The compounds can be similarly reacted with HX in the presence of compounds of formula L1 and / or L2 to obtain the desired precursor compounds.

[0053] The present methods provide certain compounds which in turn can be used to vapor deposit certain Group VI metals onto various substrates, including microelectronic semiconductor device substrates. Thus, in another aspect, the present invention provides a method of forming a material on a substrate comprising contacting the substrate with a compound of formula (I)

[0054]

[0055] wherein M is selected from molybdenum, chromium and tungsten, X is selected from fluorine, chlorine, bromine and iodine, and each L1 and L2 are the same or different and constitute:

[0056] (i) a monodentate hydrocarbon-based ligand coordinated to M, or

[0057] (ii) together form a bidentate hydrocarbon ligand coordinated to M;

[0058] A material containing molybdenum, chromium or tungsten is deposited on a substrate under vapor deposition conditions.

[0059] The substrate used in the deposition method of the present invention may be of any suitable type and may include, for example, a semiconductor device substrate, such as a silicon substrate, a silicon dioxide substrate, or other silicon-based substrate. In various embodiments, the substrate may include one or more metal or dielectric substrates, such as Co, Cu, Al, W, WN, WC, TiN, Mo, MoC, SiO2, W, SiN, WCN, Al2O3, AlN, ZrO2, HfO2, SiO2, lanthanum oxide (La2O3), tantalum nitride (TaN), ruthenium oxide (RuO2), iridium oxide (IrO2), niobium oxide (Nb2O3), and yttrium oxide (Y2O3).

[0060] In certain embodiments, such as in the case of an oxide substrate (eg, silicon dioxide) or another alternative silicon or polysilicon substrate, the substrate may be processed or fabricated to include a barrier layer (eg, titanium nitride) thereon for subsequently deposited materials.

[0061] In one embodiment, the molybdenum, chromium or tungsten containing layer deposited on the substrate surface can be formed by, for example, pulsed chemical vapor deposition (CVD) or atomic layer deposition (ALD) or other vapor deposition techniques, without the need to preform a nucleation layer and thus directly using the vapor derived from the compound of formula (I). The corresponding formula (I) vapor contact step can be alternately and repeatedly performed as many cycles as required to form a molybdenum, chromium or tungsten film of the desired thickness. In various embodiments, the contact of the substrate (e.g., titanium nitride) layer with the vapor is performed at a temperature as low as 350° C. and in other embodiments in the range of 300° C. to 750° C.

[0062] Using vapors derived from compounds of formula (I), materials containing molybdenum, chromium or tungsten can be deposited directly on a substrate to form a bulk deposit of elemental molybdenum, chromium or tungsten or their corresponding oxides. The concentration of H2 is critical to the formation of the metal or oxide because metal formation requires greater than four molar equivalents or an excess of H2. Less than four (4) molar equivalents of H2 will result in the formation of varying amounts of oxides of the metal, and thus further exposure to H2 will be required to reduce the metal oxides thus formed.

[0063] In various embodiments, the molybdenum, chromium, or tungsten containing material is deposited on the substrate surface at a temperature in the range of 300° C. to 750° C. The method may be implemented such that the vapor deposition conditions cause deposition of elemental molybdenum, chromium, or tungsten as the metal-containing material on the substrate. The vapor deposition conditions may have any suitable characteristics and may include, for example, the presence of hydrogen or other reducing gases to form a bulk layer of elemental molybdenum, chromium, or tungsten on the substrate.

[0064] More generally, according to the present disclosure, a broad method of forming a material containing molybdenum, chromium, or tungsten on a substrate may include vapor deposition conditions including the presence of hydrogen or other reducing gases. The material containing molybdenum, chromium, or tungsten may be deposited on a barrier layer or surface in the presence or absence of hydrogen. For example, the barrier layer may be composed of titanium nitride, and the titanium nitride layer may be contacted with a vapor derived from a compound of formula (I) in the presence of hydrogen.

[0065] In another embodiment, when using the compound of formula (I) as a means of depositing metal oxide films (such as MoO2, WO3 and Cr2O3), an oxidizing co-reactant (such as oxygen) can be added to the process.

[0066] It should be understood that the present invention can be implemented in many alternative ways and under a wide variety of process conditions. The present method can be implemented, for example, in a process for manufacturing a semiconductor device on a substrate. The semiconductor device can be of any suitable type and can include, for example, a DRAM device, a 3-D NAND device, or other device or device integration structure. In various embodiments, the substrate can include a through hole in which a molybdenum-containing material is deposited. For example, the device can have an aspect ratio of depth to lateral dimension in the range of 10:1 to 40:1. In still other embodiments, the device can be a film for use in a flat panel display or a mobile device.

[0067] According to the present invention, the process chemistry for depositing a molybdenum-containing material may include depositing elemental molybdenum, Mo(0), by the following reaction: 2MO2Cl2[(L1)(L2)]+6H2→2M (wherein M=molybdenum, chromium or tungsten)+4HCl+4H2O. The molybdenum-, chromium- or tungsten-containing material (M) deposited according to the method of the present invention may be characterized by any appropriate evaluation indicators and parameters, such as the deposition rate of the molybdenum-, chromium- or tungsten-containing material, the film resistivity of the deposited molybdenum-, chromium- or tungsten-containing material, the film morphology of the deposited molybdenum-, chromium- or tungsten-containing material, the film stress of the deposited molybdenum-, chromium- or tungsten-containing material, the step coverage of the material, and the process window or process envelope of appropriate processing conditions. Any appropriate evaluation indicators and parameters may be used to characterize the deposited material and associate it with specific process conditions to enable mass production of the corresponding semiconductor product. Advantageously, the method of the present invention enables a high-purity molybdenum, chromium or tungsten film to be deposited on a semiconductor device. Therefore, in another aspect, the present invention provides a semiconductor device having a molybdenum film deposited thereon, wherein the film contains greater than 99% molybdenum, chromium or tungsten.

[0068] In certain embodiments, the present disclosure relates to a method for forming a material containing molybdenum, chromium or tungsten on a substrate, which comprises depositing molybdenum, chromium or tungsten on the surface of the substrate using a precursor compound of formula (I) by a chemical vapor deposition (CVD) process to produce a material containing molybdenum, chromium or tungsten on the substrate.

[0069] The process can be implemented in any suitable manner as described in various aspects herein. In a specific embodiment, the method can be implemented using a vapor deposition process comprising chemical vapor deposition (e.g., pulsed chemical vapor deposition). The method can be implemented so that the resulting material containing molybdenum, chromium or tungsten is essentially composed of elemental molybdenum, chromium or tungsten, and in various embodiments, molybdenum, chromium or tungsten can be deposited on the substrate surface in the presence of hydrogen or other suitable reducing gases. In other embodiments of the present invention, the precursor of formula (I) and the reducing gas can be successively delivered in a pulsed manner to deposit a molybdenum film in a pulsed manner, wherein the pulse sequence is optimized for film conformality and film resistivity. The method can be implemented in the manufacture of semiconductor device products (e.g., DRAM devices, or 3-D NAND, logic devices, flat panel displays, or IC packaging components).

[0070] Generally, the disclosed methods for forming a molybdenum, chromium or tungsten containing material on a substrate may be implemented to achieve deposition of the molybdenum, chromium or tungsten containing material at high step coverage levels (eg, step coverage in a range of about 75% to about 100%).

[0071] The present invention can be further illustrated by the following examples of preferred embodiments thereof, but it should be understood that these examples are included for illustrative purposes only and are not intended to limit the scope of the present invention unless otherwise specifically stated.

[0072] Experimental part

[0073] Compounds of formula (I) can be prepared using the following general procedures:

[0074] Synthesis procedure No. 1.

[0075] MoO3 (20.0 g, 138 mmol) was loaded in a 500 mL round-bottom flask equipped with a magnetic stirring bar. HCl (200 mL, 37%) was added directly to MoO3, the reaction flask was equipped with a water-cooled condenser (5 ° C), and the resulting light green suspension was heated to near reflux (95 ° C) using an oil bath. After about 2 hours, the reaction was presented as a clear light green solution. The reaction was cooled to room temperature and then placed in an ice bath. At this point, DME (50 mL) was directly added to the cooled solution and the reaction was warmed to room temperature and stirred overnight. The next morning, the light green solution was poured into a 1 L separatory funnel and extracted with DCM (2 x 200 mL). The organic layers were combined, dried using MgSO4, filtered, placed in a 1 L round-bottom flask equipped with a magnetic stirring bar, and the solvent was removed under reduced pressure to obtain MoO2Cl2 (dimethoxyethane) as an off-white solid. Quality = 12.68 g, yield = 31.8%. The product can be purified by vacuum sublimation (80°C at 25 mTorr). 1H NMR (400MHz, C6D6, 298K): δ3.29 (s, 6H); 2.78 (s, 4H) ppm. 13 C{1H}NMR (100MHz, C6D6, 298K): δ70.68, 64.13ppm.

[0076] Synthesis Procedure No. 2

[0077] General formula A2MO4, where M = chromium, molybdenum or tungsten and A = lithium, sodium or potassium.

[0078] Here, the general synthesis procedure and post-processing are very similar to Procedure 1

[0079]

[0080] That is, compounds of the general formula A2MO4, wherein M is selected from chromium, molybdenum or tungsten, and A is selected from Group I and Group II metals or ammonium cations. Examples include Li + 、Na + , K + NH4 + , alkyl ammonium compounds, etc.

[0081] Synthesis Procedure No. 3

[0082] Ligand substitution can be utilized to synthesize compounds of formula (I). For example, the MoO2Cl2(N,N-dimethylformamide)2 complex can be prepared using Procedure No. 1 above, and then the N,N-dimethylformamide ligand is substituted for dimethoxyethane via solvolysis to produce MoO2Cl2(dimethoxyethane).

[0083] As mentioned above, Figure 1 The three-dimensional solid-state crystal structure of MoO2Cl2(CH3CN)2 is shown. This compound was subjected to x-ray crystallography and the following data were obtained:

[0084] Table 1. Crystal data and structure refinement of MoO2Cl2(CH3CN)2.

[0085]

[0086]

[0087] Table 2. Atomic coordinates (×10 4 ) and equivalent isotropic displacement parameters U(eq) is defined as the orthogonalized U ij One third of the tensor's trace.

[0088]

[0089]

[0090] Table 3. Bond lengths of MoO2Cl2(CH3CN) and angle [°].

[0091]

[0092]

[0093]

[0094]

[0095] Symmetry transformations used to generate equivalent atoms:

[0096] #1x,-y+1 / 2,z #2x,-y+3 / 2,z

[0097] Table 4. Anisotropic displacement parameters of MoO2Cl2(CH3CN) The anisotropic displacement factor exponent takes the following form: -2π 2 [h 2 a* 2 U 11 +...+2h ka*b*U 12 ]

[0098]

[0099]

[0100] Table 5. Hydrogen coordinates of MoO2Cl2(CH3CN) (×10 4 ) and isotropic displacement parameters

[0101]

[0102] As mentioned above, Figure 2 It is a three-dimensional solid-state crystal structure depiction of WO2Cl2(CH3CN)2.

[0103] Table 6. Crystal data and structure refinement of WO2Cl2(CH3CN)2.

[0104]

[0105] Table 7. Atomic coordinates of WO2Cl2(CH3CN)2 (×10 4 ) and equivalent isotropic displacement parameters U(eq) is defined as the orthogonalized U ijOne third of the tensor's trace.

[0106]

[0107] Table 8. Bond lengths of WO2Cl2(CH3CN)2 and angle [°].

[0108]

[0109]

[0110] Symmetry transformations used to generate equivalent atoms:

[0111] #1-x+1,y,-z+1 / 2

[0112] Table 9. Anisotropic displacement parameters of WO2Cl2(CH3CN)2 The anisotropic displacement factor exponent takes the following form: -2π 2 [h 2 a* 2 U 11 +...+2h ka*b*U 12 ]

[0113]

[0114] Table 10. Hydrogen coordinates of WO2Cl2(CH3CN)2 (×10 4 ) and isotropic displacement parameters

[0115]

[0116] As mentioned above, Figure 5 It is a three-dimensional solid-state crystal structure depiction of MoO2Cl2(THF)2 (THF = tetrahydrofuran).

[0117] This compound was subjected to x-ray crystallography analysis and the following data were obtained:

[0118] Table 11. Crystal data and structure refinement of MoO2Cl2(THF)2.

[0119]

[0120]

[0121] Table 12. Atomic coordinates (×10 4 ) and equivalent isotropic displacement parameters For Example 11, U(eq) is defined as the orthogonalized U ij One third of the tensor's trace.

[0122]

[0123]

[0124] Table 13. Bond lengths of MoO2Cl2(THF)2 and angle [°].

[0125]

[0126]

[0127]

[0128]

[0129] Symmetry transformations used to generate equivalent atoms:

[0130] Table 14. Anisotropic displacement parameters of MoO2Cl2(THF)2 The anisotropic displacement factor exponent takes the following form: -2π 2 [h 2 a* 2 U 11 +...+2h ka*b*U 12 ]

[0131]

[0132] Table 15. Hydrogen coordinates of MoO2Cl2(THF)2 (×10 4 ) and isotropic displacement parameters

[0133]

[0134] The following table illustrates various physical properties of certain compounds of formula (I):

[0135]

[0136] abbreviation:

[0137] DME = 1,2-dimethoxyethane DMM = 1,2-dimethoxymethane 1,2-DMP=1,2-dimethoxypropane DMA=N,N-dimethylacetamide DMF=N,N-dimethylformamide DMCA = N,N-dimethylcyanoacetamide TMEN=N,N,N',N'-tetramethylethylenediamine CN = Nitrile THF = Tetrahydrofuran

[0138] STA-DSC:

[0139] Simultaneous thermal analysis-differential scanning calorimetry.

Claims

1. A method for forming a material on a substrate, comprising contacting the substrate with a compound of formula (I) wherein M is molybdenum, X is chlorine, and L1 and L2 are acetonitrile; and depositing a molybdenum-containing material on the substrate under vapor deposition conditions, The compound of formula (I) has an orthorhombic system and a unit cell size of α＝90° β＝90° γ = 90°.

2. A method for forming a material on a substrate, comprising contacting the substrate with a compound of formula (I) wherein M is tungsten, X is chlorine, and L1 and L2 are acetonitrile; and depositing a tungsten-containing material on the substrate under vapor deposition conditions, The compound of formula (I) has an orthorhombic system and a unit cell size of α＝90° β＝90° γ = 90°.

3. A method for forming a material on a substrate, comprising contacting the substrate with a compound of formula (I) wherein M is molybdenum, X is chlorine, and L1 and L2 are tetrahydrofuran; and depositing a molybdenum-containing material on the substrate under vapor deposition conditions, The compound of formula (I) has an orthorhombic system and a unit cell size of α＝90° β＝90° γ = 90°.

4. A compound of formula (I) wherein M is molybdenum, X is chlorine, and L1 and L2 are acetonitrile; and wherein the compound of formula (I) is crystalline and has less than 1% impurities by weight, and wherein the compound of formula (I) has an orthorhombic system and a unit cell size of α＝90° β＝90° γ = 90°.

5. A compound of formula (I) wherein M is tungsten, X is chlorine, and L1 and L2 are acetonitrile; and wherein the compound of formula (I) is crystalline and has less than 1% impurities by weight, and wherein the compound of formula (I) has an orthorhombic system and a unit cell size of α＝90° β＝90° γ = 90°.

6. A compound of formula (I) wherein M is molybdenum, X is chlorine, and L1 and L2 are tetrahydrofuran; and wherein the compound of formula (I) is crystalline and has less than 1% impurities by weight, and The compound of formula (I) has an orthorhombic system and a unit cell size of α＝90° β＝90° γ = 90°.

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