Method for forming a molybdenum-containing film deposited on a metal element film

Abstract

A method for forming a molybdenum-containing film is provided. The method includes thermally evaporating a first film on a surface of a substrate at a first temperature, e.g., about 400°C or less, and thermally evaporating a molybdenum-containing film (second film) on at least a portion of the first film at a second temperature, e.g., above about 400°C. The first film can include a metallic element, e.g., tungsten, molybdenum, ruthenium, or cobalt. The second film includes a reaction product of a molybdenum-containing precursor and a reducing agent.

Description

Detailed Description of the Invention

[0001] [Technical Field] The present invention relates to a method for forming a molybdenum-containing film deposited on an elemental film.

[0002] [Background technology] A variety of precursors are used to form thin films, and various deposition techniques are employed. These techniques include reactive sputtering, ion-assisted deposition, chemical vapor deposition (CVD) (also known as metalorganic CVD or MOCVD), and atomic layer deposition (also known as atomic layer epitaxy). CVD and ALD processes are increasingly being used due to their advantages of improved compositional control, high film uniformity, and effective control of doping. Furthermore, CVD and ALD processes provide excellent conformal step coverage in the highly nonplanar structures associated with modern microelectronic devices.

[0003] CVD is a chemical process that uses precursors to form thin films on a substrate surface. In a typical CVD process, precursors are passed over the surface of a substrate (e.g., a wafer) in a low-pressure or atmospheric-pressure reaction chamber. The precursors react and / or decompose on the substrate surface, producing a thin film of deposit. Plasma can be used to aid the precursor reaction or to improve material properties. Volatile byproducts are removed by gas flow through the reaction chamber. Controlling the thickness of the deposited film can be difficult because it depends on a combination of many parameters, including temperature, pressure, gas flow volume and uniformity, chemical depletion effects, and time.

[0004] ALD is a chemical method for the deposition of thin films. It is a unique, self-limiting, continuous film growth technique based on surface reactions. This surface reaction allows for precise control of thickness, allowing the deposition of conformal thin films of materials provided by precursors on substrates of various compositions. In ALD, precursors are separated during the reaction. The first precursor is passed over the substrate surface, forming a monolayer on the substrate surface. Excess unreacted precursor is pumped out of the reaction chamber. Next, a second precursor or co-reactant is passed over the substrate surface and reacts with the first precursor, forming a second monolayer on the first monolayer formed on the substrate surface. Plasma may be used to enhance the precursor or co-reactant reaction or to improve material quality. This cycle is repeated to prepare a film of the desired thickness.

[0005] Thin films, especially metal-containing thin films, have a variety of important applications in nanotechnology and semiconductor device fabrication, etc. Examples of such applications include capacitor electrodes, gate electrodes, adhesive diffusion barriers, and integrated circuits.

[0006] The continuing shrinking of microelectronic component sizes is driving the need for improved thin-film technology. Furthermore, there is a need to deposit molybdenum as a next-generation metal electrode and cap or liner in the fabrication of logic and memory semiconductors. Low-resistivity molybdenum films can be deposited by ALD or CVD using H2 reduction of molybdenum halides, such as MoCl5, or oxyhalides, such as MoO2Cl2, at higher temperatures (e.g., above 400°C). At such high temperatures, molybdenum films may grow little or not at all on oxide and nitride surfaces due to long nucleation delays, or may suffer from scattered island growth. While diborane can be used to deposit boron as a nucleation layer, the use of diborane can result in non-uniform deposition as well as boron contamination. Therefore, a process is needed for forming molybdenum-containing films on metal-containing liners that can achieve lower resistivity films with improved molybdenum nucleation.

[0007] Summary of the Invention Accordingly, provided herein is a method for forming a molybdenum-containing film on a substrate. The method includes thermally depositing a first film comprising a metal element on a surface of the substrate at a first temperature of about 400°C or less. The metal element can be tungsten, molybdenum, or a combination thereof. The method further includes thermally depositing a second film on at least a portion of the first film at a second temperature greater than about 400°C. The second film comprises the reaction product of a molybdenum-containing precursor and a reducing agent.

[0008] In another embodiment, another method of forming a molybdenum-containing film on a substrate is provided herein. The method includes thermally depositing a first film comprising a metal element on a surface of the substrate at a first temperature of about 400°C or less. The metal element may be selected from the group consisting of ruthenium, cobalt, and combinations thereof. The method further includes thermally depositing a second film on at least a portion of the first film at a second temperature greater than about 400°C. The second film comprises the reaction product of a molybdenum-containing precursor and a reducing agent.

[0009] Other embodiments, incorporating particular aspects of the present embodiments summarized above, will become apparent from the following detailed description.

[0010] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graphical representation of thermogravimetric analysis (TGA) data showing weight (%) of MoO2Cl2 versus temperature.

[0011] FIG. 2A is a graphical representation of growth rate (Å / pulse) versus deposition temperature (° C.) for molybdenum-containing films grown on a SiO substrate, a WCN substrate, a molybdenum elemental first film, and a ruthenium elemental first film according to Example 2.

[0012] FIG. 2B is a graphical representation of resistivity (μΩ-cm) and molybdenum thickness (Å) versus deposition temperature (° C.) for molybdenum-containing films grown on elemental molybdenum first films according to Example 2.

[0013] FIG. 3A is a graphical representation of growth rate (Å / cycle) versus deposition pressure (Torr) for molybdenum-containing films grown on Al2O3 substrates, SiO2 substrates, WCN substrates, TiN substrates, and elemental ruthenium first films according to Example 3.

[0014] FIG. 3B is a graphical representation of resistivity (μΩ-cm) versus deposition pressure (Torr) for a molybdenum-containing film grown on a WCN substrate and elemental ruthenium first film according to Example 3.

[0015] FIG. 4 is a graphical representation of the X-ray photoelectron spectroscopy (XPS) chemical composition of a molybdenum-containing film deposited on an elemental ruthenium first film according to Example 4.

[0016] 5A and 5B are scanning electron microscope (SEM) images of a molybdenum-containing film deposited on an elemental ruthenium first film.

[0017] FIG. 5C is an SEM image of a molybdenum-containing film deposited on an Al2O3 substrate.

[0018] 5D and 5E are SEM images of molybdenum-containing films deposited on WCN substrates.

[0019] 6A-6C are cross-sectional SEM images of the via structure of a SiO substrate having a molybdenum-containing film deposited directly in the via structure, on a TiN liner in the via structure, and on a molybdenum elemental first film liner deposited in the via structure, respectively.

[0020] 7A and 7B are cross-sectional SEM images of a TiN pore structure with a molybdenum-containing film deposited directly within the TiN pore structure.

[0021] 7C and 7D are cross-sectional SEM images of a molybdenum-containing film deposited on a first film liner of elemental molybdenum deposited within a TiN pore structure.

[0022] 〔Detailed Description〕 Before describing examples of some embodiments of the present technology, it should be understood that the present technology is not limited to the details of the configurations or process steps described in the following description. The present technology is capable of other embodiments and can be implemented or executed in various ways.

[0023] The inventors have discovered a process comprising two steps for improving molybdenum deposition and the films formed therefrom. The process can include a first step of depositing a first film or liner, such as a molybdenum element-containing film or a ruthenium element-containing film, on a substrate using a first metal-containing precursor and a co-reactant. A second film (i.e., a molybdenum-containing film) can be formed on the first film by delivering a molybdenum-containing precursor and a reducing agent during a second step. Advantageously, the process described herein can be carried out at a lower temperature. For example, the first step can be carried out at a temperature of 400 °C or less. Furthermore, a second conformal molybdenum-containing film having a low resistivity can be achieved.

[0024] (Definitions) For the purposes of the present invention and the claims, the numbering scheme for the groups of the periodic table follows the IUPAC periodic table of the elements.

[0025] As used herein, the term "and / or" in phrases such as "A and / or B" is intended to include "A and B", "A or B", "A", and "B".

[0026] The terms "substituent", "radical", "group", and "moiety" may be used interchangeably.

[0027] As used herein, the terms "metal-containing complex" (or more simply "complex") and "precursor" are used interchangeably and refer to a metal-containing molecule or compound that can be used to prepare a metal-containing film by a vapor deposition process, such as ALD or CVD. The metal-containing complex may be deposited, adsorbed, decomposed, delivered, and / or passed onto a substrate or surface thereof to form a metal-containing film.

[0028] As used herein, "metal-containing film" includes not only elemental metal films, as more fully defined below, but also films that contain a metal along with one or more elements, such as metal nitride films, metal silicide films, metal carbide films, and the like.

[0029] As used herein, the terms "metal element," "metal element film," and "pure metal film" are used interchangeably to refer to a film consisting of pure metal or consisting essentially of pure metal. For example, a metal element film may contain 100% pure metal, or a metal element film may contain at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.9%, or at least about 99.99% pure metal, along with one or more impurities. However, films containing metal elements are distinguished from binary films containing a metal and a nonmetal (e.g., C, N) and ternary films containing a metal and two nonmetals (e.g., C, N), although films containing metal elements may contain some impurities. Unless the context dictates otherwise, the term "metal film" shall be interpreted to mean a metal element film.

[0030] As used herein, the terms "vapor deposition process" and "thermally depositing" are used to refer to any type of vapor deposition technique, including, but not limited to, CVD and ALD. In various embodiments, CVD may take the form of conventional (i.e., continuous flow) CVD, liquid injection CVD, plasma-enhanced CVD, or photo-assisted CVD. CVD may take the form of a pulsed technique (i.e., pulsed CVD). ALD is used to form metal-containing films by vaporizing and / or passing at least one metal complex disclosed herein over a substrate surface. For a description of conventional ALD processes, see, for example, George S. M., et al. J. Phys. Chem., 1996, 100, 13121-13131. In other embodiments, ALD may take the form of conventional (i.e., pulsed injection) ALD, liquid injection ALD, photo-assisted ALD, plasma-assisted ALD, or plasma-enhanced ALD. The term "vapor deposition process" may include various vapor deposition techniques described in Chemical Vapor Deposition: Precursors, Processes, and Applications; Jones, AC; Hitchman, ML, Eds. The Royal Society of Chemistry: Cambridge, 2009; Chapter 1, pp 1-36.

[0031] <Method for forming a molybdenum-containing film> As described above, a method for forming a molybdenum-containing (Mo-containing) film is provided herein. The method may include a first step and a second step. In an optional embodiment, the first step may include forming a first film (or liner) on a surface of a substrate. The first film may include a metal element. For example, the metal element may be selected from the group consisting of tungsten (W), molybdenum (Mo), ruthenium (Ru), cobalt (Co), and combinations thereof. In an optional embodiment, the metal element may be tungsten (W), molybdenum (Mo), or a combination thereof. In another embodiment, the metal element may be selected from the group consisting of ruthenium (Ru), cobalt (Co), and combinations thereof.

[0032] The first film comprising a metal element (e.g., Mo, Ru) can have a thickness as measured by X-ray fluorescence (XRF) of about 1 nm or more, about 2 nm or more, about 4 nm or more, about 6 nm or more, about 8 nm or more, about 10 nm or more, about 12 nm or more, about 15 nm; or about 1 nm to about 15 nm, about 2 nm to about 12 nm, about 2 nm to about 10 nm, or about 6 nm to about 12 nm.

[0033] Additionally or alternatively, the first film comprising a metal element (e.g., Mo, Ru) may have a conductivity of about 300 μΩ.cm or less, about 250 μΩ.cm or less, about 200 μΩ.cm or less, about 175 μΩ.cm or less, about 150 μΩ.cm or less, about 125 μΩ.cm or less, or 100 μΩ.cm or less; or about 100 μΩ.cm to about 300 μΩ.cm, about 100 μΩ.cm to about 250 μΩ.cm, about 100 μΩ.cm to about 200 μΩ.cm, or about 100 μΩ.cm to about 150 μΩ.cm.

[0034] In any embodiment, thermally depositing the first film includes delivering a first metal-containing precursor and a co-reactant to the substrate. The first metal-containing precursor may be any suitable tungsten-containing precursor, molybdenum-containing precursor, ruthenium-containing precursor, cobalt-containing precursor, or combinations thereof. Examples of molybdenum-containing precursors include, but are not limited to, molybdenum halides, molybdenum oxyhalides, molybdenum hexacarbonyl, or combinations thereof. Suitable molybdenum halides include, but are not limited to, MoCl5 or MoF6. Suitable molybdenum oxyhalides include, but are not limited to, MoOCl4 or MoO2Cl2. Examples of tungsten precursors include, but are not limited to, WCl5, WF6, and W(CO)6. Examples of ruthenium-containing precursors include, but are not limited to, zerovalent ruthenium (Ru(0)) precursors, such as, for example, η-2,3-dimethylbutadiene ruthenium tricarbonyl ((DMBD)Ru(CO)) and (ethylbenzyl)(1-ethyl-1,4-cyclohexadienyl) (EtBz)Ru(EtCHD). In some embodiments, the first film is formed by delivering to the substrate a first metal-containing precursor comprising a molybdenum halide as described herein and a co-reactant as further described below. In other embodiments, the first film is formed by delivering to the substrate a first metal-containing precursor comprising a zerovalent ruthenium precursor as described herein and a co-reactant as further described below.

[0035] In various embodiments, the co-reactant can be selected from the group consisting of nitrogen plasma, ammonia plasma, oxygen, air, water, HO, ozone, NH, H, i-PrOH, t-BuOH, NO, ammonia, alkylhydrazine, hydrazine, ozone, 1,4-di-trimethylsilyl-2-methyl-cyclohexa-2,5-diene (CHD), 1-trimethylsilylcyclohexa-2,5-diene, 1,4-bis-trimethylsilyl-1,4-dihydropyrazine (DHP), and combinations of any two or more thereof. In various embodiments, the alkylhydrazine can be C-C-alkylhydrazine, C-C-alkylhydrazine, or C-C-alkylhydrazine. For example, the alkylhydrazine can be methylhydrazine, ethylhydrazine, propylhydrazine, or butylhydrazine (including tertiary butylhydrazine).

[0036] In any embodiment, the second step of the method can include thermally depositing a second film (also referred to as a "molybdenum-containing film") on at least a portion of the first film. Thermally depositing the second film includes delivering a molybdenum-containing precursor and a reducing agent to the substrate. The second film can include a reaction product of the molybdenum-containing precursor and the reducing agent. The second film can also optionally include a dissociated portion of the molybdenum-containing precursor, a dissociated portion of the reducing agent, or a combination thereof. The molybdenum-containing precursor can be, for example, a molybdenum halide, a molybdenum oxyhalide, or a combination thereof. The molybdenum halide can be MoCl5 or MoF6, and the molybdenum oxyhalide can be MoOCl4 or MoO2Cl2. The reducing agent can be any suitable reducing agent, including, but not limited to, hydrogen, hydrogen plasma, or a combination thereof. It is contemplated herein that the first film and the second film can each be a continuous or discontinuous layer.

[0037] Advantageously, the methods described herein can result in a second film having a lower resistivity. For example, the second film may have a resistivity of about 300 μΩ-cm or less, about 250 μΩ-cm or less, about 200 μΩ-cm or less, about 175 μΩ-cm or less, about 150 μΩ-cm or less, about 125 μΩ-cm or less, about 100 μΩ-cm or less, about 75 μΩ-cm or less, about 50 μΩ-cm or less; or about 30 μΩ-cm; or about 30 μΩ-cm to about 300 μΩ-cm, about 30 μΩ-cm to about 200 μΩ-cm, about 30 μΩ-cm to about 175 μΩ-cm, about 30 μΩ-cm to about 150 μΩ-cm, about 30 μΩ-cm to about 100 μΩ-cm, or about 30 μΩ-cm to about 50 μΩ-cm.

[0038] In any embodiment, the first step, the second step, or a combination thereof can include the use of plasma. The use of plasma can, for example, promote the reaction of one or more of the first metal-containing precursor, the molybdenum-containing precursor, the co-reactant, and the reducing agent. Additionally or alternatively, the use of plasma can improve film quality.

[0039] In some embodiments, the first metal-containing precursor, the molybdenum-containing precursor, or a combination thereof may be dissolved in a suitable solvent, such as a hydrocarbon or amine solvent, to facilitate the deposition process. Suitable hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons such as hexane, heptane, and nonane; aromatic hydrocarbons such as toluene and xylene; and aliphatic and cyclic ethers such as diglyme, triglyme, and tetraglyme. Examples of suitable amine solvents include, but are not limited to, octylamine and N,N-dimethyldodecylamine. For example, the first metal-containing precursor, the molybdenum-containing precursor, or a combination thereof may be dissolved in toluene to obtain a solution having a concentration of about 0.05 M to about 1 M.

[0040] In an alternative embodiment, the first metal-containing precursor, the molybdenum-containing precursor, or a combination thereof can be delivered to the substrate surface "neat" (undiluted by a carrier gas). Thus, the precursors disclosed herein and utilized in these methods can be liquid, solid, or gaseous. Typically, the ruthenium precursor and the molybdenum precursor are liquid or solid at ambient temperature with sufficient vapor pressure to allow consistent vapor transport into, for example, a process chamber at a temperature higher than ambient temperature.

[0041] In various embodiments, the substrate surface can comprise a metal, a dielectric material, a metal oxide material, or a combination thereof. The dielectric material can be a low-κ dielectric or a high-κ dielectric. Examples of suitable dielectric materials include, but are not limited to, SiO2, SiON, Si3N4, and combinations thereof. Examples of suitable metal oxide materials include, but are not limited to, HfO2, ZrO2, SiO2, Al2O3, TiO2, and combinations thereof. Other suitable substrate materials include, but are not limited to, crystalline silicon, Si(100), Si(111), glass, strained silicon, silicon-on-insulator (SOI), doped silicon or silicon oxide (e.g., silicon oxide doped with carbon), germanium, gallium arsenide, tantalum, tantalum nitride, aluminum, copper, ruthenium, titanium, titanium nitride, tungsten, tungsten nitride, tungsten carbonitride (WCN), and any number of other substrates commonly encountered in nanoscale device fabrication processes (e.g., semiconductor fabrication processes). In some embodiments, the substrate may comprise one or more of silicon oxide, aluminum oxide, titanium nitride, tungsten nitride, tungsten carbonitride, and tantalum nitride. As will be appreciated by those skilled in the art, the substrate may be subjected to a pretreatment process to polish, etch, reduce, oxidize, hydroxylate, anneal, and / or bake the substrate surface. In one or more embodiments, the substrate surface comprises a hydrogen-terminated surface.

[0042] The methods provided herein, particularly the thermal evaporation of the first and second films, include, but are not limited to, various types of ALD and CVD processes such as continuous injection processes or pulse injection processes, liquid injection processes, photo-assisted processes, plasma-assisted processes, and plasma-enhanced processes. For purposes of clarity, the methods of the present technology specifically include direct liquid injection processes. For example, in direct liquid injection CVD ("DLI-CVD"), there may be a means of vaporizing a solid or liquid metal complex by dissolving it in a suitable solvent and injecting the resulting solution into a vaporization chamber. The vaporized metal complex is then transported / delivered to the substrate surface. Generally, DLI-CVD can be particularly useful in instances where the metal complex exhibits relatively low volatility or is otherwise difficult to vaporize. For example, the first and second steps may each independently be an ALD process or a CVD process.

[0043] In some embodiments, conventional CVD or pulsed CVD is used to form the first film described herein and / or the second film described herein by vaporizing and / or passing a first metal-containing precursor and / or a molybdenum-containing precursor (all described herein) over the substrate surface. For conventional CVD processes, see, for example, Smith, Donald (1995). Thin-Film Deposition: Principles and Practice. McGraw-Hill.

[0044] In other embodiments, photo-assisted CVD is used to form the first film described herein and / or the second film described herein by vaporizing and / or passing a first metal-containing precursor and / or a molybdenum-containing precursor (all described herein) over the substrate surface.

[0045] In one embodiment, the CVD growth conditions for the first metal-containing precursor and / or the molybdenum-containing precursor disclosed herein include, but are not limited to, the following: (1) Substrate temperature: 50~600 °C (2) Evaporator temperature (metal precursor temperature): 0~120 °C (3) Reactor pressure: 0~200 Torr (4) Flow rate of argon or nitrogen carrier gas: 0~100 sccm (5) Oxygen flow rate: 0~100 sccm (6) Hydrogen flow rate: 0~50 sccm (7) Metal precursor pulse time: 0.01~5 s (8) Purge gas pulse time: 1~30 s (9) Execution time: Varies according to the desired film thickness.

[0046] In another embodiment, a metal-containing film is formed by using photo-assisted CVD to vaporize and / or pass a first metal-containing precursor and / or a molybdenum-containing precursor (all described herein) onto the substrate surface.

[0047] In some embodiments, conventional (i.e., pulsed injection) ALD is used to form a first film as described herein and / or a second film as described herein by vaporizing and / or passing a first metal-containing precursor and / or a molybdenum-containing precursor (all described herein) onto the substrate surface. For conventional ALD methods, see, for example, George S. M., et al. J. Phys. Chem., 1996, 100, 13121-13131.

[0048] In other embodiments, liquid injection ALD is used to form a first film as described herein and / or a second film as described herein by vaporizing and / or passing a first metal-containing precursor and / or a molybdenum-containing precursor (all described herein) over a substrate surface. The aforementioned precursors are delivered to the reaction chamber by direct liquid injection as opposed to vapor aspiration by a bubbler. For liquid injection ALD processes, see, e.g., Potter R. J., et al., Chem. Vap. Deposition, 2005, 11(3), 159-169.

[0049] In other embodiments, photo-assisted ALD is used to form a first film as described herein and / or a second film as described herein by vaporizing and / or passing a first metal-containing precursor and / or a molybdenum-containing precursor (all described herein) over a substrate surface. See, e.g., U.S. Patent No. 4,581,249 for photo-assisted ALD methods.

[0050] In other embodiments, plasma-assisted or plasma-enhanced ALD is used to form a first film as described herein and / or a second film as described herein by vaporizing and / or passing a first metal-containing precursor and / or a molybdenum-containing precursor (all described herein) over a substrate surface.

[0051] Examples of ALD growth conditions for the first metal-containing precursors and / or molybdenum-containing precursors disclosed herein include, but are not limited to: (1) Substrate temperature: 200 - 700 °C (2) Evaporator temperature (metal precursor temperature): 20 - 150 °C (3) Reactor pressure: 0.01 - 200 Torr (4) Flow rate of argon or nitrogen carrier gas: 0 - 100 sccm (5) Reactive gas (co-reactant or reducing agent) pulse time: 0.01 to 30 seconds (6) Metal precursor pulse time: 0.01 to 10 seconds (7) Purge gas pulse time: 1 to 10 seconds (8) Pulse sequence (metal complex / purge / reactive gas / purge): May vary depending on chamber size.

[0052] (9) Number of cycles: Varies depending on the desired film thickness, for example, 1 to 100 cycles.

[0053] The reaction time, temperature, and pressure of the method described herein are selected to produce a first film and a second film on the surface of the substrate. The reaction conditions are selected based on the properties of the first metal-containing precursor and the molybdenum-containing precursor. The first and second steps can be performed at atmospheric pressure, but are more commonly performed at reduced pressure. For example, during the first step, the thermal evaporation of the first film can be performed at a pressure of about 0.01 Torr or greater, about 0.1 Torr or greater, about 0.5 Torr or greater, about 1 Torr or greater, about 2 Torr or greater, about 4 Torr or greater, about 6 Torr or greater, about 8 Torr or greater, or about 10 Torr or greater; or about 0.01 Torr to about 10 Torr, about 0.1 Torr to about 8 Torr, about 0.1 Torr to about 6 Torr, or about 2 Torr to about 6 Torr. Additionally or alternatively, during the second step, thermal evaporation of the second film can be carried out at a pressure of about 1 Torr or greater, about 5 Torr or greater, about 10 Torr or greater, about 25 Torr or greater, about 50 Torr or greater, about 75 Torr or greater, about 100 Torr or greater, about 150 Torr or greater, or about 200 Torr; or about 1 Torr to about 200 Torr, about 1 Torr to about 100 Torr, about 1 Torr to about 50 Torr, or about 5 Torr to about 10 Torr.

[0054] The vapor pressures of the first metal-containing precursor and the molybdenum-containing precursor must be high enough to be practical for such applications. The substrate temperature must be low enough to maintain the integrity of the bonds between the surface metal atoms and prevent thermal decomposition of the gaseous reactants. However, the substrate temperature must also be high enough to keep the source materials (i.e., reactants) in the gas phase and provide sufficient activation energy for the surface reaction. The appropriate temperature depends on various parameters, including the specific first metal-containing precursor and molybdenum-containing precursor used, as well as the pressure. In some embodiments, during the first step, thermal evaporation of the first film can be carried out at a lower temperature, such as about 500°C or less, about 450°C or less, about 400°C or less, about 350°C or less, about 300°C or less, about 290°C or less, about 275°C or less, about 250°C or less, about 225°C or less, or about 200°C; or at a first temperature of about 200°C to about 500°C, about 200°C to about 400°C, about 200°C to about 300°C, or about 225°C to about 290°C. Additionally or alternatively, during the second step, thermal evaporation of the second film can be carried out at a higher temperature, e.g., about 300°C or higher, about 350°C or higher, about 400°C or higher, about 450°C or higher, about 500°C or higher, about 550°C or higher, about 600°C or higher, about 650°C or higher, or about 700°C; or at a second temperature of about 300°C to about 700°C, about 400°C to about 600°C, about 400°C to about 500°C, or about 400°C to about 450°C. The above temperatures are understood to represent the substrate temperature. In any embodiment, the first step, the second step, or both steps may be carried out in an inert atmosphere (e.g., an argon atmosphere).

[0055] The properties of specific first metal-containing precursors and molybdenum-containing precursors for use in the deposition methods disclosed herein can be evaluated using methods known in the art, allowing for the selection of appropriate reaction temperatures and pressures. Generally, low molecular weights and the presence of functional groups that increase the rotational entropy of the ligand sphere result in melting points that produce liquids at typical delivery temperatures and increased vapor pressures.

[0056] The first metal-containing precursor and the molybdenum-containing precursor for use in the vapor deposition method will have all of the requirements for sufficient vapor pressure, sufficient thermal stability at the temperature of the selected substrate, and sufficient reactivity to cause a reaction on the surface of the substrate without containing undesirable impurities in the thin film. Sufficient vapor pressure ensures that the molecules of the source compound are present on the surface of the substrate at a concentration sufficient to allow a complete self-saturation reaction. Sufficient thermal stability ensures that the source compound does not undergo thermal decomposition that produces impurities in the thin film.

[0057] In a further embodiment, the first step (e.g., during an ALD process) can include a first step cycle that includes delivering a first metal-containing precursor, a co-reactant, and a purge gas to the substrate. For example, the first metal-containing precursor can be pulsed for 0.01 to 1 second, followed by delivering the purge gas for 2 to 15 seconds, followed by pulsing the co-reactant for 0.001 to 3 seconds, followed by delivering the purge gas for 2 to 15 seconds. The number of first step cycles can range from 1 to 100 cycles, 1 to 75 cycles, 1 to 50 cycles, 1 to 25 cycles, 1 to 10 cycles, or 1 to 5 cycles.

[0058] In various aspects, the second step (e.g., during a pulsed CVD process) can include a second step cycle that includes delivering a molybdenum-containing precursor, e.g., pulsing the molybdenum-containing precursor to the substrate in a stream of a reducing agent and a purge gas. For example, the molybdenum-containing precursor can be pulsed for about 0.01 to 2 seconds in a stream of the reducing agent and the purge gas. The reducing agent and the purge gas flow for about 5 to 30 seconds. In some embodiments, the reducing agent can flow for a shorter period than the purge gas. Alternatively, the reducing agent, the purge gas, or both can be delivered to the substrate, e.g., about 5 to 30 seconds after pulsing the molybdenum-containing precursor. The number of pulses of the molybdenum-containing precursor is determined by the desired thickness of the molybdenum-containing film and can range, for example, from 1 to 500 pulses, 1 to 300 pulses, 1 to 200 pulses, 1 to 100 pulses, 1 to 50 pulses, or 1 to 25 pulses.

[0059] In an alternative embodiment, the second step (e.g., during an ALD process) can include a second step cycle that involves delivering a molybdenum-containing precursor, a reducing agent, and a purge gas to the substrate. For example, the molybdenum-containing precursor can be pulsed for 0.01 to 2 seconds, followed by delivering the purge gas for 2 to 10 seconds, followed by pulsing the reducing agent for 2 to 15 seconds, and followed by delivering the purge gas for 2 to 10 seconds. The number of second step cycles can range from 1 to 1000 cycles, 1 to 750 cycles, 1 to 500 cycles, 1 to 250 cycles, 1 to 100 cycles, 1 to 75 cycles, 1 to 50 cycles, 1 to 25 cycles, 1 to 10 cycles, or 1 to 5 cycles.

[0060] As any suitable purge gas that can be used in the first and second steps, for example, nitrogen, hydrogen, and noble gases such as helium, neon, argon, krypton, xenon, etc. can be used.

[0061] In a further embodiment, the method described herein may be performed under conditions that provide conformal growth, for example, for a first film, a second film, or a combination thereof. As used herein, the term "conformal growth" refers to a deposition process in which the film is deposited with substantially the same thickness along one or more of the bottom surface, side surfaces, upper corners, and the outside of the feature. "Conformal growth" is also intended to encompass some variation in film thickness. For example, the film may be thicker near the outside of the feature and / or at the top or upper part of the feature compared to the bottom or lower part of the feature.

[0062] The first step (e.g., first step cycle) and / or the second step can be performed under conformal conditions such that conformal growth occurs. Conformal conditions include, but are not limited to, the temperature (e.g., of the substrate, first metal-containing precursor, molybdenum-containing precursor, purge gas, co-reactant, reducing agent, etc.), the pressure (e.g., during delivery of the first metal-containing precursor, molybdenum-containing precursor, purge gas, co-reactant, reducing agent, etc.), the amount of first metal-containing precursor, molybdenum-containing precursor, purge gas, co-reactant, and / or reducing agent delivered, the length of purge time, and / or the amount of purge gas delivered.

[0063] In various embodiments, the substrate can include one or more features in which conformal growth can occur. In various embodiments, the features can be holes, trenches, contacts, dual damascene, etc. The features can have non-uniform widths, also known as "recessed features," or the features can have substantially uniform widths.

[0064] In any embodiment, the first film, the second film, or both grown according to the methods described herein may be substantially continuous and conformal. In one or more embodiments, the first film, the second film, or both grown according to the methods described herein may be substantially free of seams that are voids and / or cavities.

[0065] In various embodiments, the method includes delivering a first metal-containing precursor, a purge gas, and at least one co-reactant to the surface of a substrate under sufficient conditions to (i) deposit metal elements such that a first film grows conformably over at least a portion of the substrate and etch a portion of the first film; (ii) deposit metal elements, etch a portion of the first film, and enable desorption of the etched portion of the first film; or (iii) deposit metal elements and enable desorption of a portion of the first film. Under such conditions, the first metal-containing precursor may be subjected to one or more of the following processes: (i) a process of depositing metal elements and etching a portion of the first film; (ii) a process of depositing metal elements, etching a portion of the first film, and enabling desorption of the etched portion of the first film; or (iii) a process of depositing metal elements and enabling desorption of a portion of the first film. Additionally or alternatively, the co-reactant may be capable of depositing metal elements.

[0066] In some embodiments, the first and second films may be deposited within the same reaction vessel. Alternatively, the first and second films may be deposited in different reaction vessels. For example, the first film may be deposited on a substrate within a first reaction vessel, and then the substrate on which the first film is deposited may be transferred to a second reaction vessel. The second film may be deposited over at least a portion of the first film.

[0067] In any embodiment, the methods described herein may further include annealing the as-deposited first film, the as-deposited second film, or both films at a higher temperature. In other words, annealing can be performed after the last cycle for forming the first film and / or the last cycle for forming the second film.

[0068] Thus, in some embodiments, the as-deposited first film, the as-deposited second film, or both films may be annealed under vacuum or in the presence of an inert gas such as Ar or N, or a reducing agent such as H, or a combination thereof, such as, for example, 5% H in Ar. Without being bound by theory, the annealing step may remove incorporated carbon, oxygen, and / or nitrogen by densification at high temperatures to reduce resistivity and further improve film quality. Annealing may be performed at temperatures above about 400°C, above about 700°C, or about 800°C; between about 300°C and about 800°C, or between about 500°C and about 800°C.

[0069] [Application] Films formed from the processes described herein are useful for memory and / or logic applications such as dynamic random access memory (DRAM), complementary metal oxide semiconductor (CMOS), and 3D NAND, 3D crosspoint, and ReRAM.

[0070] Throughout this specification, references to "one embodiment," "a particular embodiment," "one or more embodiments," or "an embodiment" mean that a particular feature, structure, material, or characteristic described in connection with this embodiment is included in at least one embodiment of the present technology. Thus, the appearances of phrases such as "in one or more embodiments," "a particular embodiment," "in one embodiment," or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment of the present technology. Furthermore, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0071] Although the present technology has been described with reference to specific embodiments, it should be understood that these embodiments merely illustrate the principles and applications of the present technology. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatuses of the present technology without departing from the spirit and scope of the present technology. Accordingly, the present technology is intended to include modifications and variations that fall within the scope of the appended claims and their equivalents. Thus, having generally described the present technology, it will be more readily understood by reference to the following examples, which are provided for illustrative purposes and are not intended to be limiting.

[0072] [Example] <General conditions> MoCl (obtained from Strem Chemicals Inc.), MoOCl (obtained from Millipore Sigma), and (DMBD)Ru(CO) (also referred to as RuDMBD) were utilized as precursors in the following examples. Methods for preparing (DMBD)Ru(CO) are known in the art. See, for example, U.S. Patent Application Publication No. 2011 / 0165780, which is incorporated herein by reference. Unless otherwise specified, film thicknesses were measured by XRF, and film resistivities were based on ellipsometer thickness.

[0073] (I. 1st step) Unless otherwise stated, a first film of elemental ruthenium was deposited on a substrate using (DMBD)Ru(CO)3 and O2 in an ALD process in a CN1 ALD / CVD reactor. The reactor conditions were as follows:

[0074] i. Substrate temperature: 250℃ ii. (DMBD)Ru(CO)3 at 40 °C was delivered to the substrate as follows: a 1 second (DMBD)Ru(CO)3 pulse (bubbler), a 10 second argon purge, a 3 second O2 coreactant (20 sccm) pulse, and a 10 second argon purge.

[0075] Unless otherwise specified, in the ALD process in the Ultratech Savannah S200 reactor, the first film of molybdenum element was deposited on the substrate using MoCl5 and CHD. The reactor conditions were as follows.

[0076] i. Substrate temperature: 280 °C ii. MoCl5 at 114 °C was delivered to the substrate as follows: a 1 - second MoCl5 pulse, a 2 - second purge with nitrogen, a 3 - second CHD co - reactant pulse at 50 °C, and a 2 - second purge with nitrogen.

[0077] (II. Second step) Unless otherwise specified, in the pulsed CVD process in the CN1 ALD / CVD reactor, a molybdenum - containing film was deposited using MoO2Cl2 and H2. The reactor conditions were as follows.

[0078] i. Substrate temperature: 430 °C - 490 °C.

[0079] ii. MoO2Cl2 at 85 °C was pulsed using a constant H2 flow in Ar: a 1 - 2 - second MoO2Cl2 pulse and a 10 - 30 - second purge with H2 in Ar.

[0080] <Example 1 - Thermogravimetric analysis of MoO2Cl2> Thermogravimetric analysis (TGA) of MoO2Cl2 was performed, and the results are shown in Figure 1. Mo2O2Cl2 showed a clean evaporation at ~170 °C and contained a small residue (1.6%). The vapor pressure of MoO2Cl2 is Log P(Torr)=11.747-(3830 / T).

[0081] <Example 2 - Influence of deposition temperature on growth rate and resistivity> The first film of molybdenum element was grown on a SiO2 substrate under the above-mentioned ALD conditions. The molybdenum-containing film was deposited on the first film of molybdenum element (on "Mo") by the above-mentioned CVD conditions using 60% H2, a pressure of 2.0 Torr, and 300 pulses at four different substrate temperatures of 430 °C, 450 °C, 470 °C, and 490 °C. The first film of ruthenium element was grown on a SiO2 substrate under the above-mentioned ALD conditions. The molybdenum-containing film was deposited on the first film of ruthenium element (on "Ru") by the above-mentioned CVD conditions using 60% H2, a pressure of 2.0 Torr, and 300 pulses at four different substrate temperatures of 430 °C, 450 °C, 470 °C, and 490 °C. Also, the molybdenum-containing film was deposited on a SiO2 substrate (on "SiO2") and on a WCN substrate (on "WCN") by the above-mentioned CVD conditions using 60% H2, a pressure of 2.0 Torr, and 300 pulses at four different substrate temperatures of 430 °C, 450 °C, 470 °C, and 490 °C. As shown in Fig. 2A, the growth rates of the molybdenum-containing films at four different temperatures were measured. It was observed that a metal Mo film was deposited on the metals of the first films of molybdenum element and ruthenium element. Also, the growth of Mo was slow on WCN, and almost no growth of Mo was seen on SiO2. As shown in Fig. 2B, the resistivity and thickness were also measured for the molybdenum-containing films on Mo at four different temperatures.

[0082] <Example 3 - Influence of Deposition Pressure on Growth Rate and Resistivity> The first film of ruthenium element was grown on the SiO2 substrate under the above-mentioned ALD conditions, and the molybdenum-containing film was deposited on the first film of ruthenium element ("Ru") under the above-mentioned CVD conditions with the substrate temperature being 490 °C and three different pressures of 3.6 Torr, 4.9 Torr, and 5.8 Torr. Also, the molybdenum-containing film was deposited on the Al2O3 substrate ("Al2O3"), SiO2 substrate ("SiO2"), TiN substrate ("TiN"), and WCN substrate ("WCN") under the above-mentioned CVD conditions with the substrate temperature being 490 °C and three different pressures. As shown in Figure 3A, the growth rates of the molybdenum-containing film at three different pressures were measured. The growth rate did not seem to be affected by the deposition pressure. As shown in Figure 3B, the resistivity was also measured for the molybdenum-containing film deposited at three different pressures at 490 °C. It was found that the resistivity decreased with the increase of the deposition pressure. The lowest resistivity was found to be the molybdenum-containing film grown on the first film of ruthenium element, which was ~37 μΩ-cm at 5.8 Torr.

[0083] <Example 4 - XPS Analysis of Molybdenum-Containing Film on the First Film of Ruthenium> XPS analysis of the molybdenum-containing film deposited on the first film of ruthenium element was performed under the above-mentioned CVD conditions of 490 °C and 5.8 Torr. As a result, as shown in Figure 4, it was confirmed that there was no Cl or C in the molybdenum-containing film, and about 6 at% of O was present.

[0084] <Example 5 - Comparison of Molybdenum-Containing Films on Various Surfaces> A 6-nm-thick ruthenium first film was grown on a SiO substrate using the ALD conditions described above, and a molybdenum-containing film was deposited on the ruthenium first film using the CVD conditions described above, with a substrate temperature of 490°C and a pressure of 5.8 Torr. Figure 5A is an SEM image of a vertical cross-section of the molybdenum-containing film on the ruthenium first film, showing a continuous molybdenum film (approximately 20 nm thick). Figure 5B is an SEM image of a top view of the molybdenum-containing film of Figure 5A. A molybdenum-containing film was deposited on an Al2O3 substrate using the CVD conditions described above, with a substrate temperature of 490°C and a pressure of 5.8 Torr. Figure 5C is an SEM image of a top view of the molybdenum-containing film on an Al2O3 substrate, showing isolated molybdenum islands. A molybdenum-containing film was also deposited on a WCN substrate using the CVD conditions described above, with a substrate temperature of 490°C and a pressure of 5.8 Torr. Figure 5D is an SEM image of a vertical cross section of a molybdenum-containing film on a WCN, showing scattered molybdenum crystals, and Figure 5E is an SEM image of a top view of the molybdenum-containing film of Figure 5D.

[0085] Example 6 - Formation of a film in a via of a SiO2 substrate A molybdenum-containing film was deposited on the pores present in the SiO2 substrate under the above-described CVD conditions with a substrate temperature of 490 °C. FIG. 6A is an SEM image of a vertical cross-sectional view of a SiO2 pore that does not show molybdenum growth except at the bottom, due to the trapped precursors. A TiN liner was deposited on the SiO2 pore by ALD at 225 °C using tetrakis(dimethylamido)titanium (TDMAT) and ammonia. A molybdenum-containing film was deposited on the TiN liner (thickness of about 2 nm) in the pores present in the SiO2 substrate under the above-described CVD conditions with a substrate temperature of 490 °C. FIG. 6B is an SEM image of a vertical cross-sectional view of a TiN-reinforced SiO2 (TiN lined SiO2) pore showing molybdenum growth as islands with large particles. A first film of molybdenum element (thickness 2.5 nm) was grown in the pores present in the SiO2 substrate under the above-described ALD conditions with a substrate temperature of 280 °C, and a molybdenum-containing film was deposited on the first film of molybdenum element under the above-described CVD conditions with a substrate temperature of 490 °C. FIG. 6C is an SEM image of a vertical cross-sectional view of a Mo-reinforced SiO2 (Mo lined SiO2) pore showing a uniform, conformal, and smooth molybdenum-containing film (thickness of about 20 nm).

[0086] <Example 7 - Film Formation in Pores of TiN Substrate> A molybdenum-containing film was deposited in the pores of the TiN substrate with a substrate temperature of 490 °C under the above-described CVD conditions. FIGS. 7A and 7B are SEM images of a vertical cross-sectional view of a TiN pore showing a molybdenum-containing film as large particles. A first film of molybdenum element (Mo liner, thickness 3.2 nm) was grown in the pores of the TiN substrate under the above-described ALD conditions with a substrate temperature of 280 °C, and a molybdenum-containing film was deposited on the first film of molybdenum element under the above-described CVD conditions. FIGS. 7C and 7D are SEM images of a vertical cross-sectional view of a Mo-reinforced TiN (Mo lined TiN) pore, showing the growth of a uniform, conformal molybdenum-containing film as small particles.

[0087] All publications, patent applications, issued patents, and other documents mentioned in this specification are hereby incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions contained in incorporated documents are excluded to the extent they conflict with definitions in the present disclosure.

[0088] The terms "comprise", "comprises", and "comprising" are to be construed inclusively rather than exclusively.

Brief Description of the Drawings

[0089]

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Claims

1. A method for forming a molybdenum-containing film, comprising: A. A step of thermally depositing a first film containing a metal element on the surface of a substrate at a first temperature of 400 °C or lower, wherein the metal element is selected from the group consisting of ruthenium, cobalt, and combinations thereof; B. A step of thermally depositing a second film on at least a part of the first film at a second temperature exceeding 400 °C, wherein the second film contains a reaction product of a molybdenum-containing precursor and a reducing agent.

2. The method according to claim 1, wherein the first film contains a ruthenium element and the first film has a thickness of 2 nm or more.

3. The method according to claim 1 or 2, wherein the step of thermally depositing the first film includes delivering a first metal-containing precursor and a co-reactant to the substrate, and the first metal-containing precursor is a ruthenium-containing precursor.

4. The ruthenium-containing precursor is η4-2,3-dimethylbutadiene ruthenium tricarbonyl ((DMBD)Ru(CO) ３ ) or (ethylbenzyl)(1-ethyl-1,4-cyclohexadienyl)(EtBz)Ru(EtCHD), the method according to claim 3.

5. The method according to any one of claims 1 to 4, wherein the step of thermally depositing the second film includes delivering the molybdenum-containing precursor and the reducing agent to the substrate, and the molybdenum-containing precursor is molybdenum halide or oxyhalide molybdenum.

6. The molybdenum halide is MoCl ５ or MoF ６ and the molybdenum oxyhalide is MoOCl ４ or MoO ２ Cl ２ The method according to claim 5

7. The reducing agent is hydrogen or a hydrogen plasma, and / or the co-reactant is 1,4-di-trimethylsilyl-2-methyl-cyclohexa-2,5-diene (CHD), 1,4-bis-trimethylsilyl-1,4-dihydropyrazine (DHP), 1-trimethylsilylcyclohexa-2,5-diene, nitrogen plasma, ammonia plasma, oxygen, air, water, ozone, NH ３ , H ２ , hydrazine, alkyl hydrazine, and combinations thereof, the method according to claim 3, selected from the group consisting of.

8. The method according to any one of claims 1 to 7, wherein the first temperature is 300 °C or lower.

9. The method according to any one of claims 1 to 8, wherein the second temperature is 400 °C to 600 °C.

10. The method according to any one of claims 1 to 9, wherein the second film is substantially continuous and conformal.

11. The method according to any one of claims 1 to 10, wherein the second film has a resistivity of 200 μΩ-cm or less.

12. The method according to any one of claims 1 to 11, wherein the step of thermally depositing the first film is performed at a pressure of 0.1 Torr to 6 Torr, and / or the step of thermally depositing the second film is performed at a pressure of 1 Torr to 100 Torr.

13. The method according to any one of claims 1 to 12, wherein the step of thermally depositing the second film is performed at a pressure of 5 Torr to 10 Torr.

14. The method according to any one of claims 1 to 13, wherein the first film is thermally deposited by chemical vapor deposition or atomic layer deposition, and / or the second film is thermally deposited by chemical vapor deposition or atomic layer deposition.

15. The method according to any one of claims 1 to 14, wherein the substrate comprises one or more of silicon oxide, aluminum oxide, titanium nitride, tungsten nitride, tungsten carbonitride, and tantalum nitride.

16. The method according to any one of claims 1 to 15, wherein the first film and the second film are deposited in the same reaction vessel, or the first film and the second film are deposited in different reaction vessels.

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