Molybdenum precursor compounds

Abstract

The present invention provides certain molybdenum-containing compounds believed to be useful for the deposition of molybdenum-containing films on the surfaces of various microelectronic device substrates. In one aspect, the present invention provides a method for depositing a molybdenum-containing film on a microelectronic device substrate, comprising exposing the substrate to a compound of formula (I) as described herein in a reaction zone under deposition conditions.

Description

Technical Field

[0001] Priority Claim This invention claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 277,829, filed Nov. 10, 2021. This priority document is hereby incorporated by reference into this specification.

[0002] This invention relates to certain molybdenum compounds useful as precursors in the deposition of molybdenum-containing films onto microelectronic device substrates.

Background Art

[0003] Group 6 metals such as molybdenum, chromium, and tungsten are increasingly being used in the manufacture of semiconductor devices due to their extremely high melting points, low thermal expansion coefficients, low resistivity, and high thermal conductivity, including the use of diffusion barriers, electrodes, photomasks, power electronics substrates, low-resistance gates, flat panel displays, and interconnects.

[0004] Such usefulness has motivated efforts to achieve the deposition of molybdenum, chromium, and tungsten films for such applications, characterized by high conformity and high deposition rates of the deposited films, in order to accommodate efficient mass manufacturing operations. For this reason, efforts have been made to develop improved molybdenum and tungsten feed reagents useful for deposition operations, and improved process parameters using such reagents.

[0005] In atomic layer deposition (ALD), reactants and precursor molecules are introduced into the reaction zone in alternating pulses to form a layer with the desired chemical composition. These precursors are supplied to the wafer in gaseous form. This method is well-established for precursors that are gaseous at standard temperatures and pressures. The precursor gas flows directly into the deposition chamber. The trend towards new interconnect materials requires a broader portfolio of precursors, many of which are liquid or solid at room temperature. These ALD precursors must have sufficient volatility, thermal stability, and reactivity with the substrate and the film to be deposited. Whether liquid or solid, the vapor pressure of the precursor determines the process conditions.

[0006] Most liquid precursors are supplied at room temperature and vaporize when the pressure is reduced. Generally, liquids are easier to purify, handle, and supply than solid precursors. Therefore, many vertically integrated device manufacturers (IDMs) prefer liquid supply systems.

[0007] Solids are more difficult to process because they require heating of both the material and the gas lines supplying it. Ideally, the precursor should be non-flammable, non-corrosive, non-toxic, easy to manufacture, and inexpensive. [Overview of the Initiative]

[0008] In summary, the present invention provides a specific molybdenum-containing compound that is considered useful for depositing molybdenum-containing films onto the surface of various microelectronic device substrates. In one embodiment, the present invention provides a method for depositing a molybdenum-containing film on a microelectronic device substrate, wherein, in a reaction zone, under deposition conditions, the substrate is subjected to a compound of formula (I): TIFF0007880961000001.tif37170[wherein each R is independently selected from (i) C1-C4 alkyl or (ii) C1-C4 alkyl substituted with one or more halogen atoms]; The present invention provides a method for forming a molybdenum-containing film on a substrate, which includes exposure to a certain substance. [Brief explanation of the drawing]

[0009] [Figure 1] [Example] This graph shows the thermogravimetric analysis of a molybdenum(II) acetate dimer compound, indicating that 50% of its mass is evaporated by 310°C. [Figure 2] This graph shows the thermogravimetric analysis of a common precursor, HfCl4, indicating that 50% of its mass is evaporated by 290°C; therefore, as a reference example, molybdenum(II) acetate dimer can be supplied at a similar temperature in deposition techniques such as ALD. [Modes for carrying out the invention]

[0010] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” refer to multiple subjects unless explicitly indicated otherwise. As used herein and in the appended claims, the term “or” generally refers to “and / or” unless explicitly indicated otherwise.

[0011] The term "approximately" generally refers to a range of numbers that are considered equivalent to the value mentioned (e.g., having the same function or result). Often, the term "approximately" may include numbers that are rounded to the nearest significant digit.

[0012] A numerical range expressed using an endpoint includes all numbers contained within that range (for example, 1-5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0013] In a first aspect, the present invention provides a method for depositing a molybdenum-containing film on a microelectronic device substrate, comprising exposing the substrate to a compound of formula (I) in a reaction zone. TIFF0007880961000002.tif38170[wherein each R is independently selected from (i) C1-C4 alkyl or (ii) C1-C4 alkyl substituted with one or more halogen atoms; Under the deposition conditions, a molybdenum-containing film is formed on the substrate.

[0014] In one embodiment, each R is selected from methyl, tert-butyl, and trifluoromethyl.

[0015] The compound of formula (I) shown above exists as a dimer of a molybdenum-containing alkanoate. In other words, the compound of formula (I) is empirically... TIFF0007880961000003.tif20170[In the formula, R is as defined above] It holds.

[0016] Many compounds of formula (I) are known and can be prepared by treating molybdenum hexacarbonyl (Mo(CO)6) with acetic acid (i.e., when R is methyl). Similarly, other carboxylic acids can be used for the corresponding R group in formula (I). (See, for example, *Rhenium and Molybdenum Compounds Containing Quadruple Bonds*, Alicia B. Brignole, FA.Cotton, Z. Dori, Z. Dori, Z. Dori, G. Wilkinson; book editor: FA.Cotton; first edition: January 1, 1972; see https: / / doi.org / 10.1002 / 9780470132449.ch15. Furthermore, when R is methyl, molybdenum(II) acetate dimer compounds are commercially available from Sigma Aldrich (CAS number 14221-06-8).)

[0017] The compound of formula (I) is considered useful for chemical vapor deposition of molybdenum-containing films. In this context, the term "molybdenum-containing" film refers to a film composed of one or more of the following: molybdenum metal, molybdenum oxide, molybdenum carbide, and molybdenum nitride.

[0018] Chemical deposition methods include those known as chemical vapor deposition (CVD) and atomic layer deposition (ALD), which also include several derivative versions such as UV laser photodissociation CVD, plasma-assisted CVD, pulsed CVD, and plasma-assisted ALD. In the deposition of high-purity metals onto two-dimensional or three-dimensional microelectronic device substrates, these types of deposition methods are sometimes desirable because they result in high purity of the deposited metal and can often provide good conformal step coverage to highly non-planar microelectronic device shapes.

[0019] In one embodiment, the molybdenum-containing film or layer deposited on the substrate surface can be formed, for example, by chemical vapor deposition, pulsed chemical vapor deposition (CVD), or atomic layer deposition (ALD), and thus directly using vapor derived from the compound of formula (I).

[0020] In one embodiment, the compound of formula (I) is introduced together with a reducing gas into a reaction zone containing a microelectronic device substrate. The conditions of the reaction zone are selected so that the molybdenum contained in the precursor of formula (I) is deposited on the microelectronic device substrate as molybdenum metal. In one embodiment, the precursor and the reducing gas are introduced into the reaction zone continuously. In another embodiment, an oxidizing gas such as oxygen, ozone, or a combination of water and hydrogen can be introduced into the reaction zone to improve the composition of the deposited metal layer. Thus, the oxidizing gas is introduced in an amount and manner that reduces the amount of carbon deposited in the finished molybdenum layer. In one embodiment, this oxidizing gas is introduced intermittently in a pulsed manner. Further details of this technique can be found in U.S. Patent Publication 2020 / 0115798, which is incorporated herein by reference.

[0021] Accordingly, in one embodiment, the present invention provides a method for depositing a molybdenum-containing film on a microelectronic device substrate, comprising introducing a precursor of formula (I) into a reaction zone containing the microelectronic device substrate and simultaneously introducing a reducing gas into the reaction zone. In another embodiment, the method further comprises the step of intermittently introducing pulses of an oxidizing gas into the reaction zone.

[0022] In another embodiment, a molybdenum precursor of formula (I) can be introduced into a reaction zone containing a microelectronic device substrate, followed by pulsed introduction of an oxidizing gas (e.g., H2O vapor), and then pulsed introduction of a reducing gas (e.g., H2). In this way, a molybdenum metal film can be deposited on the surface of the microelectronic device substrate. Thus, in a further embodiment, the present invention provides a method for depositing a molybdenum-containing film on a microelectronic device substrate, comprising (i) introducing a precursor of formula (I) into a reaction zone containing a microelectronic device substrate, while intermittently (ii) exposing the substrate to an oxidizing gas; and intermittently (iii) exposing the substrate to a reducing gas. In a particular embodiment, the precursor, the oxidizing gas, and the reducing gas are pulsed into the atomic layer deposition region.

[0023] In certain embodiments of the present invention, the oxidizing gas is composed of a gas selected from H2O vapor, H2O2, O3, and N2O. In certain embodiments of the present invention, the reducing gas is composed of a gas selected from H2, hydrazine (N2H4), methylhydrazine, t-butylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, and NH3. Considering the oxidation potentials of H2O2 and O3, it will be understood that such gases should not be used with hydrazine (N2H4), methylhydrazine, t-butylhydrazine, 1,1-dimethylhydrazine, or 1,2-dimethylhydrazine, or, if used sequentially, any such gas remaining from such a process should be purged from the reactor before exposing the substrate to other reactants. Further details regarding these techniques can be found in U.S. Patent Publication No. 2021 / 062331, which is incorporated herein by reference.

[0024] In certain cases, nitrogen-containing reducing gases such as ammonia (NH3), hydrazine (N2H4); methylhydrazine, t-butylhydrazine, 1,1-dimethylhydrazine, and 1,2-dimethylhydrazine, such as C1-C4 alkylhydrazines, may be useful, but under some conditions, a molybdenum-containing nitride film rather than a pure metal film is provided. Similarly, in certain embodiments, carbon-containing reducing gases such as carbon monoxide, alkanes, alkenes, and alkynes may be useful, but under some conditions, a molybdenum carbide film rather than a pure metal film is provided. In one embodiment, the reducing gas is hydrogen.

[0025] The methods disclosed herein can include one or more purge gases as an optional step during the introduction of a metal precursor and a reducing gas and / or an oxidizing gas, and a carrier gas. The purge gas or carrier gas used either to purge away unconsumed reactants and / or reaction by-products or to function as a diluent and carrier for the metal precursor and the reducing or oxidizing gas is an inert gas that does not react with the precursor. Exemplary gases include, but are not limited to, argon, nitrogen, helium, neon, and mixtures thereof. In certain embodiments, a purge gas such as Ar is supplied into the reactor at a flow rate in the range of about 10 to about 10000 sccm for about 0.1 to 1000 seconds, thereby purging unreacted materials and any by-products that may remain in the reactor. Additionally, such an inert gas can be utilized as a carrier gas to vary the concentration of the molybdenum precursor and / or the oxidizing gas and / or the reducing gas injected into the reaction zone, as used herein. The utilization and flow rate of the carrier gas ultimately depend on the configuration of the deposition tool, the scale of its operation, and the particular precursor utilized.

[0026] In one embodiment, a reducing gas can be utilized with the precursor of formula (I) to effect the formation of an elemental molybdenum-containing film. Alternatively, when using the precursors described herein as a means to deposit a metal oxide thin film such as MoO2, an oxidizing gas (i.e., a co-reactant) such as oxygen can be added to the method.

[0027] In various embodiments, the deposition conditions include an inert atmosphere, except for the optional presence of such a reducing gas and / or an oxidizing gas. In certain embodiments, the precursor vapor can be deposited in the substantial absence of other metal vapors.

[0028] In certain embodiments, the molybdenum-containing layer deposited on the substrate surface can be formed, for example, by chemical vapor deposition (CVD), pulsed chemical vapor deposition, atomic layer deposition (ALD), or other (thermal) vapor deposition methods without prior formation of a nucleating layer. Each precursor vapor contact step can be alternately repeated for a desired number of cycles to form the molybdenum-containing film to the desired thickness. In various embodiments, contact between the substrate (e.g., titanium nitride) layer and the compound vapor of formula (I) is carried out at a temperature in the range of 200°C to 750°C and a pressure of about 0.5 to about 500 Torr for such deposition. The pulsed introduction of the compound of formula (I), reducing gas, and oxidizing gas can, in certain embodiments, have a duration in the range of about 0.2 seconds to about 60 seconds.

[0029] As described above, molybdenum metal-containing materials can be deposited directly onto a substrate to form bulk deposits of molybdenum metal, oxides, carbides, or nitrides. When the deposition of an elemental molybdenum film is desired and H2 is used as the reducing gas, the concentration of H2 is important for the formation of molybdenum metal versus oxide, as more than 4 molar equivalents of H2, or an excess of H2, are required for metal formation. At less than 4 molar equivalents of H2, various amounts of molybdenum metal oxide are formed, and therefore, further exposure to H2 is required to reduce the molybdenum oxide thus formed.

[0030] Process chemistry for depositing such molybdenum-containing materials in accordance with this disclosure may include the deposition of elemental molybdenum, Mo(0), by the reaction Mo2(O2CCH3)4 + 2H2 → 2Mo + 4HOCCH3. Intermediate reactions may be present and are well known in the art.

[0031] Molybdenum-containing materials deposited according to the method of the present invention can be characterized by any appropriate evaluation indicators and parameters, such as the deposition rate of the molybdenum-containing material, the film resistivity of the deposited molybdenum-containing material, the film morphology of the deposited molybdenum-containing material, the film stress of the deposited molybdenum-containing material, the step coverage of the material, the film composition and purity, and the process window or process envelope of appropriate process conditions. By employing any appropriate evaluation indicators and parameters to characterize the deposited material and associating it with specific process conditions, it is possible to enable mass production of corresponding semiconductor products and flat panel displays. Advantageously, the method of the present invention is considered capable of depositing films of high-purity molybdenum metal on microelectronic device substrates.

[0032] The substrate used in the deposition method of the present invention can be any suitable type, and may include, for example, microelectronic device substrates, such as silicon substrates, silicon dioxide substrates, or other silicon-based substrates. 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), niobium nitride, ruthenium oxide (RuO2), iridium oxide (IrO2), niobium oxide (Nb2O3), and yttrium oxide (Y2O3).

[0033] In certain embodiments, for example, in the case of an oxide substrate such as silicon dioxide, or alternatively a silicon substrate or polysilicon substrate, the substrate may be processed or manufactured to include a barrier layer such as titanium nitride on it for the material to be deposited thereafter.

[0034] It will be understood that the method of the present invention can be carried out under a wide variety of process conditions by numerous alternative methods. The microelectronic or semiconductor device can be any suitable type and may include, for example, DRAM devices, 3-D NAND devices, or other devices, i.e., device integrated structures. In various embodiments, the substrate may include vias on which molybdenum-containing material is deposited. The device may have an aspect ratio of depth to lateral dimension in the range of, for example, 10:1 to 40:1. In other embodiments, the method can be carried out in the manufacture of microelectronic device products such as mobile devices, logic devices, flat panel displays, or IC packaging components.

[0035] In the method of the present invention, the precursor compound can be reacted with the surface or substrate of a desired microelectronic device in any suitable way, for example, in a single wafer chamber, a multi-wafer chamber, or a furnace containing multiple wafers.

[0036] As used herein, the term “microelectronic device” refers to semiconductor substrates, including 3D NAND structures, logic devices, DRAM, power devices, flat panel displays, and micro-electromechanical systems (MEMS), manufactured for use in microelectronics, integrated circuits, or computer chip applications. It should be understood that the term “microelectronic device” is not limited in any sense and includes any substrate, including n-channel metal-oxide-semiconductor (nMOS) and / or p-channel metal-oxide-semiconductor (pMOS) transistors, which ultimately become a microelectronic device or microelectronic assembly. Furthermore, the underlying substrate does not have to be silicon and can be an insulator such as glass or sapphire, a high-bandgap semiconductor such as SiC or GaN, or other material useful for manufacturing electrical circuits. Such microelectronic devices include at least one substrate, which can be selected from, for example, silicon, SiO2, Si3N4, OSG, FSG, silicon carbide, silicon carbide hydride, silicon nitride, silicon hydride nitride, silicon carbonitride, silicon hydride carbonitride, boron nitride, anti-reflective coatings, photoresists, germanium, germanium-containing materials, boron-containing materials, Ga / As, flexible substrates, porous inorganic materials, metals such as copper and aluminum, and diffusion barrier layers such as TiN, Ti(C)N, TaN, Ta(C)N, Ta, W, and WN. The film is suitable for various subsequent processing steps, such as chemical mechanical planarization (CMP) and anisotropic etching processes.

[0037] manner In a first aspect, the present invention provides a method for depositing a molybdenum-containing film on a microelectronic device substrate, comprising exposing the substrate to a compound of formula (I) in a reaction zone. TIFF0007880961000004.tif38170[wherein each R is independently selected from (i) C1-C4 alkyl or (ii) C1-C4 alkyl substituted with one or more halogen atoms; Under the deposition conditions, a molybdenum-containing film is formed on the substrate.

[0038] In a second aspect, the present invention provides the method of the first aspect, wherein each R is a C1-C4 alkyl group.

[0039] In a third aspect, the present invention provides the method of the first aspect, wherein each R is methyl.

[0040] In a fourth aspect, the present invention provides a method according to the first or second aspect, wherein each R is tert-butyl.

[0041] In a fifth aspect, the present invention provides the method of the first aspect, wherein each R is trifluoromethyl.

[0042] In a sixth aspect, the present invention provides a method according to any one of the first to fifth aspects, wherein the deposition conditions include a temperature of about 200°C to about 750°C and a pressure of about 0.5 to about 500 Torr.

[0043] In a seventh aspect, the present invention provides a method according to any one of the first to sixth aspects, wherein the deposition conditions include introducing a compound of formula (I) into a reaction zone containing a microelectronic device substrate and simultaneously introducing a reducing gas into the reaction zone.

[0044] In an eighth aspect, the present invention provides a method according to the seventh aspect, wherein the deposition conditions further include a step of intermittently introducing pulses of an oxidizing gas into the reaction zone.

[0045] In the ninth aspect, the present invention provides a method according to any one of the first to sixth aspects, wherein the deposition conditions include (i) introducing a precursor of formula (I) into a reaction zone containing a microelectronic device substrate, intermittently (ii) exposing the substrate to an oxidizing gas, and intermittently (iii) exposing the substrate to a reducing gas.

[0046] In a tenth aspect, the present invention provides a method according to the seventh or ninth aspect, wherein the reducing gas is composed of a gas selected from H2, hydrazine, methylhydrazine, t-butylhydrazine, 1,2-dimethylhydrazine, 1,2-dimethylhydrazine, and NH3.

[0047] In an eleventh aspect, the present invention provides a method according to the eighth or ninth aspect, wherein the oxidizing gas is selected from H2O (H2O) vapor, H2O2, O3, and N2O.

[0048] In a twelfth aspect, the present invention provides one of the first to eleventh aspects of the present invention, wherein the substrate is selected from titanium nitride, tantalum nitride, aluminum nitride, aluminum oxide, zirconium oxide, hafnium oxide, silicon dioxide, silicon nitride, lanthanum oxide, ruthenium oxide, iridium oxide, niobium oxide, and yttrium oxide.

[0049] In a thirteenth aspect, the present invention provides a method according to any one of the first to twelfth aspects, wherein the molybdenum-containing film is a molybdenum metal.

[0050] Accordingly, while several exemplary embodiments of this disclosure have been described, those skilled in the art will readily understand that other embodiments can be constructed and used within the scope of the claims appended herein. Many of the advantages of this disclosure covered herein have been described above. However, it will be understood that this disclosure is in many respects only illustrative. Of course, the scope of this disclosure is expressed in the language of the appended claims.

Claims

1. A method for depositing a molybdenum-containing film on a microelectronic device substrate, wherein the substrate is subjected to deposition conditions in a reaction zone, and a compound of formula (I): (I) [In the formula, each R is tert-butyl]; A method for forming a molybdenum-containing film on a substrate, comprising exposure to a certain substance.

2. The method according to claim 1, wherein the deposition conditions include a temperature of 200°C to 750°C and a pressure of 0.5 to 500 Torr.

3. The method according to claim 1, further comprising the step of intermittently introducing pulses of an oxidizing gas into the reaction zone as a deposition condition.

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