Substrate having metal molybdenum film, method for producing substrate, molybdenum precursor, and method for producing molybdenum precursor

Abstract

Provided are: a substrate having a metal molybdenum film with low electrical resistivity; a method for producing the substrate; a molybdenum precursor used for said production method; and a method for producing the molybdenum precursor. The present invention relates to a substrate having a metal molybdenum film in which the content of tungsten atoms in the film is 1.0 × 1016 atoms / cm3 or less.

Description

Substrate with metal molybdenum film, method for manufacturing substrate, molybdenum precursor, and method for manufacturing molybdenum precursor

[0001] The present disclosure relates to a substrate having a molybdenum metal film, a method for producing the substrate, a molybdenum precursor used in the production method, and a method for producing the molybdenum precursor.

[0002] In semiconductor device manufacturing processes, tungsten films are used as wiring formed on substrates such as semiconductor wafers (hereinafter also simply referred to as wafers) that are to be processed.

[0003] Tungsten films formed as interconnects usually have a barrier metal layer such as TiN provided along the tungsten film to prevent silicon atoms from surrounding silicon-based compounds from diffusing and forming silicide. When the wafer is viewed from above in the thickness direction, the interconnects are composed of a tungsten film and barrier metal layers provided along both sides of the tungsten film. That is, when viewed along the main surface of the substrate in a direction perpendicular to the direction in which the interconnects extend, the interconnects are composed of three layers stacked in this order: a barrier metal layer, a tungsten film, and a barrier metal layer.

[0004] In semiconductor integrated circuits, and particularly in next-generation 3D-NAND memories, the interconnect width must be reduced in order to accommodate increased memory density. As interconnect widths become smaller, the proportion of the barrier metal layer in the interconnect increases, while the proportion of the tungsten film, which is a conductive layer, decreases. This increases the electrical resistance of the interconnect, potentially reducing the performance and reliability of the device.

[0005] N. Lifshitz, et al. J. Electrochem. Soc. , 134, 2061 (1987) S. M. Georg et al. Chem. Mater. , 23, 1668 (2011)

[0006] When a tungsten film is used as wiring, a barrier metal layer is required, and therefore, in order to accommodate miniaturization of the wiring width, it is important to use a metal film that does not require a barrier metal layer. As a metal film that does not require a barrier metal layer, the present inventors have focused on a metal molybdenum film from among various metal films.

[0007] Regarding a method for forming a metallic molybdenum film, Non-Patent Document 1 describes that vapor phase deposition of metallic molybdenum was achieved using molybdenum hexafluoride and hydrogen according to the following film formation reaction formula: Film formation reaction formula: 2MoF ６ +3Si→2Mo+3SiF ４ , MoF ６ +3H ２ Furthermore, Non-Patent Document 2 describes that atomic layer deposition of metallic molybdenum was achieved using molybdenum hexafluoride and disilane according to the following deposition reaction formula: Deposition reaction formula: MoF ６ +Si ２ H ６ →Mo+2SiHF ３ +2H ２

[0008] As a result of intensive research by the present inventors, it has been newly revealed that, although the non-patent document discloses a film formation technology using a fluorine-containing molybdenum compound as a film formation precursor for a metallic molybdenum film, impurities derived from the fluorine-containing molybdenum compound are incorporated into the formed metallic molybdenum film, causing crystal defects and collisions with impurity ions, which in turn cause electrical resistance, increasing the electrical resistivity of the metallic molybdenum film and degrading device performance. Thus, the conventional technology has had the problem of high impurity concentrations in the metallic molybdenum film and high electrical resistivity.

[0009] The present disclosure aims to solve the above-mentioned problems newly discovered by the present inventors, and to provide a substrate having a molybdenum metal film with low electrical resistivity, a method for producing the substrate, a molybdenum precursor used in the production method, and a method for producing the molybdenum precursor.

[0010] Since molybdenum and tungsten are homologous elements, the molybdenum precursor used to form a metal molybdenum film generally contains tungsten as an impurity. The electrical conductivity of molybdenum (at 0°C) is 17.5 × 10 ６ S / m, and the electrical conductivity of tungsten (0°C) is 18.5 x 10 ６S / m, and tungsten has a higher electrical conductivity than molybdenum. Therefore, the present inventors had thought that tungsten present as an impurity would not affect the electrical resistivity of a metal molybdenum film. However, as a result of intensive research, the present inventors surprisingly found that the inclusion of even a trace amount of tungsten, which is a metal and has a higher electrical conductivity than molybdenum, significantly increases the electrical resistivity of a metal molybdenum film, and thus completed the present disclosure. That is, the present disclosure (1) is a method for producing a film in which the content of tungsten atoms in the film is 1.0 × 10 １６ atoms / cm ３ The present invention relates to a substrate having a metal molybdenum film as follows:

[0011] The present disclosure (2) relates to a method for manufacturing a metal molybdenum film having an electrical conductivity of 7.0×10 at 25° C. ４ The substrate according to the present disclosure (1) has a resistivity of 1.5 S / cm or more.

[0012] The present disclosure (3) also relates to a method for producing a substrate having a metallic molybdenum film, comprising: a film formation step of supplying a gas containing a molybdenum precursor and a gas containing a reducing agent to a substrate to form a metallic molybdenum film on the substrate, wherein a tungsten concentration in the molybdenum precursor is less than 100 ppb by mass.

[0013] The present disclosure (4) relates to the method for producing a substrate according to the present disclosure (3), wherein a gas containing a molybdenum precursor and a gas containing a reducing agent are simultaneously supplied in the film forming step.

[0014] The present disclosure (5) relates to the method for producing a substrate according to the present disclosure (3), wherein a gas containing a molybdenum precursor and a gas containing a reducing agent are alternately supplied in the film forming step.

[0015] The present disclosure (6) is directed to a method for producing a molybdenum precursor, which is selected from the group consisting of molybdenum halide, molybdenum oxyhalide, molybdenum carbonyl, MoCp ２ N ｔ Bu, Mo (η ３ -C ３ H ５ ) ４ , Mo ２ O ３ , MoO ２, tetrachloro(cyclopentadienyl)molybdenum, Mo(tBuN) ２ (NMe ２ ) ２ , Mo(NBu) ２ (StBu) ２ , (Me ２ N) ４ Mo, (iPrCp) ２ MoH ２ , Mo(NMe ２ ) ４ , Mo(NEt ２ ) ４ , Mo ２ (NMe ２ ) ６ , Mo(tBuN) ２ (NMe ２ ) ２ , Mo(NtBu) ２ (StBu) ２ , Mo(NtBu) ２ (iPr ２ AMD) ２ , Mo(thd) ３ , MoO ２ (acac) ２ , MoO ２ (thd) ２ , MoO ２ (iPr ２ AMD) ２ , Mo(Cp) ２ H ２ , Mo(iPrCp) ２ H ２ , and Mo(η ６ -ethylbenzene) ２ The present invention relates to a method for producing a substrate according to any one of the present disclosures (3) to (5), wherein the substrate is at least one selected from the group consisting of:

[0016] The present disclosure (7) is directed to a method for producing a molybdenum precursor, comprising: ６ The present disclosure relates to a method for manufacturing a substrate according to any one of (3) to (5).

[0017] The present disclosure (8) relates to the method for producing a substrate according to any one of the present disclosures (3) to (7), wherein the tungsten concentration in the molybdenum precursor is 10 mass ppb or less.

[0018] The present disclosure (9) relates to the method for manufacturing a substrate according to any one of the present disclosures (3) to (8), wherein the temperature of the substrate is 25° C. or higher and 800° C. or lower in the film forming step.

[0019] The present disclosure (10) relates to the method for manufacturing a substrate according to any one of the present disclosures (3) to (9), wherein in the film formation step, the outermost surface of the substrate is made of at least one material selected from the group consisting of silicon and silicon-containing compounds.

[0020] The present disclosure (11) relates to the method for manufacturing a substrate according to any one of the present disclosures (3) to (10), wherein the pressure during the film formation step is 0.1 Pa to 10 kPa.

[0021] The present disclosure (12) relates to the method for producing a substrate according to any one of the present disclosures (3) to (11), wherein the reducing agent is at least one selected from the group consisting of hydrogen, monomethylsilane, dimethylsilane, trimethylsilane, monofluorosilane, difluorosilane, trifluorosilane, silane, disilane, borane, diborane, germane, ammonia, and phosphine.

[0022] The present disclosure (13) relates to the method for manufacturing a substrate according to any one of the present disclosures (3) to (12), wherein the gas contains an inert gas.

[0023] The present disclosure (14) provides that the molybdenum precursor is MoF ６ and the MoF ６ and the reducing agent is reacted with the reducing agent so that ΔG of the reaction is in the range of −570 to −280 kJ / mol.

[0024] The present disclosure (15) provides that the molybdenum precursor is MoF ６ The method for manufacturing a substrate according to any one of (3) to (14) of the present disclosure relates to a method for manufacturing a substrate, wherein the reducing agent is hydrogen, and the substrate is heated to 350° C. or higher in the film forming step.

[0025] The present disclosure (16) provides that the molybdenum precursor is MoF ６and the reducing agent is at least one selected from the group consisting of monomethylsilane, dimethylsilane, and trimethylsilane.

[0026] The present disclosure (17) is a method for forming a film on a substrate, the outermost surface of which is formed of silicon, a silicon-containing compound, AlO ｘ , HfO ｘ , ZrO ｘ , TiN, TaN, Ti, Co, Ru, Ta and W.

[0027] The present disclosure (18) relates to the method for manufacturing a substrate according to any one of the present disclosures (3) to (17), wherein the oxygen concentration in the reaction system in the film-forming step is 10 volume ppm or less.

[0028] The present disclosure (19) also relates to a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass.

[0029] The present disclosure (20) also relates to a method for producing a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass, comprising a removal step of removing tungsten from a crude molybdenum precursor having a tungsten concentration of more than 100 ppb by mass by at least one method selected from the group consisting of distillation and adsorption using a solid metal fluoride.

[0030] The present disclosure (21) relates to the method for producing a molybdenum precursor according to the present disclosure (20), wherein the metal fluoride is at least one selected from the group consisting of alkali metal fluorides and alkaline earth metal fluorides.

[0031] The present disclosure (22) relates to the method for producing a molybdenum precursor according to the present disclosure (20) or (21), wherein the temperature of the metal fluoride is 50°C to 200°C.

[0032] The present disclosure (23) relates to a method for producing a molybdenum precursor according to any one of the present disclosures (20) to (22), in which uranium is also removed in the removal step.

[0033] The present disclosure (24) relates to a method for producing a molybdenum precursor according to any one of the present disclosures (20) to (23), wherein the tungsten concentration in the crude molybdenum precursor is 10 ppm by mass to 0.1% by mass.

[0034] The present disclosure (25) relates to a method for producing a molybdenum precursor according to any one of the present disclosures (20) to (24), in which the tungsten concentration in the produced molybdenum precursor is 10 mass ppb or less.

[0035] The present disclosure (26) relates to a method for producing a molybdenum precursor according to any one of the present disclosures (20) to (25), in which the uranium concentration in the produced molybdenum precursor is 10 mass ppb or less.

[0036] The substrate of the present disclosure has a tungsten atom content of 1.0×10 １６ atoms / cm ３ Since the substrate has a metal molybdenum film having a resistivity of 0.1 to 100%, ... and the resistivity of the metal molybdenum film is low.

[0037] The method for producing a substrate according to the present disclosure includes a film formation step of supplying a substrate with a gas containing a molybdenum precursor and a gas containing a reducing agent, and forming a molybdenum metal film on the substrate, wherein the molybdenum precursor has a tungsten concentration of less than 100 ppb by mass. The use of a molybdenum precursor with a low tungsten concentration makes it possible to form a molybdenum metal film with a low tungsten atom content, thereby enabling the production of a substrate with a molybdenum metal film with low electrical resistivity.

[0038] The molybdenum precursor of the present disclosure has a tungsten concentration of less than 100 ppb by mass, and therefore can form a metal molybdenum film with low electrical resistivity. The molybdenum precursor of the present disclosure can be suitably used in the substrate manufacturing method of the present disclosure.

[0039] The method for producing a molybdenum precursor according to the present disclosure is a method for producing a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass, which method includes a removal step of removing tungsten from a crude molybdenum precursor having a tungsten concentration of more than 100 ppb by mass using at least one method selected from the group consisting of distillation and adsorption using a solid metal fluoride, and therefore can produce a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass.

[0040] Fig. 2 is a schematic diagram showing an example of a film formation apparatus that can be used in the substrate manufacturing method of the present disclosure. Fig. 3 is a schematic diagram showing an example of an adsorption treatment using a solid metal fluoride. Fig. 4 is a schematic diagram showing the MoF2O3 film formed when a Si substrate is used under film formation temperatures of 300°C and 400°C. ６ 1 is a graph showing an example of the relationship between the Mo partial pressure and the Mo film formation rate.

[0041] The present disclosure will be described in detail below, but the following description of the constituent elements is an example of an embodiment of the present disclosure, and the present disclosure is not limited to these specific details. Various modifications can be made within the scope of the gist of the present disclosure.

[0042] In this specification, unless otherwise specified, the expression "X to Y" in the description of a numerical range means at least X and at most Y. For example, "1 to 5% by mass" means "at least 1% by mass and at most 5% by mass."

[0043] <Substrate Having Metal Molybdenum Film> The substrate of the present disclosure has a tungsten atom content of 1.0×10 １６ atoms / cm ３ Since the substrate has a metal molybdenum film having a resistivity of 0.1 to 100%, ... and the resistivity of the metal molybdenum film is low.

[0044] In this specification, the metal molybdenum film means a metal film of molybdenum.

[0045] The content of tungsten atoms in the metal molybdenum film is 1.0×10 １６ atoms / cm ３ or less, but preferably 5.0 × 10 １５ atoms / cm ３ or less, more preferably 1.0 × 10 １５atoms / cm ３ More preferably, 1.0 × 10 １４ atoms / cm ３ The lower limit is not particularly limited, but for example, 1.0 × 10 １０ atoms / cm ３ This tends to result in a metallic molybdenum film with lower electrical resistivity (higher electrical conductivity).

[0046] To form a metallic molybdenum film having a tungsten atom content within the above range, the metallic molybdenum film may be formed using, for example, a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass.

[0047] The content of fluorine atoms in the metal molybdenum film is preferably 1.0×10 １９ atoms / cm ３ or less, more preferably 1.0 × 10 １７ atoms / cm ３ More preferably, 1.0 × 10 １５ atoms / cm ３ The lower limit is not particularly limited, but for example, 1.0 × 10 １０ atoms / cm ３ This tends to result in a metallic molybdenum film with lower electrical resistivity.

[0048] The content of oxygen atoms in the metal molybdenum film is preferably 1.0×10 １９ atoms / cm ３ or less, more preferably 1.0 × 10 １７ atoms / cm ３ More preferably, 1.0 × 10 １５ atoms / cm ３ The lower limit is not particularly limited, but for example, 1.0 × 10 １０ atoms / cm ３ This tends to result in a metallic molybdenum film with lower electrical resistivity.

[0049] To form a metal molybdenum film having an oxygen atom content within the above range, the film may be formed by, for example, keeping the oxygen concentration in the reaction system low, as will be described later.

[0050] The content of silicon atoms in the metal molybdenum film is preferably 5.0×10 １９ atoms / cm ３ or less, more preferably 1.0 × 10 １９ atoms / cm ３ More preferably, 1.0 × 10 １７ atoms / cm ３ Below, particularly preferably 1.0 × 10 １５ atoms / cm ３ The lower limit is not particularly limited, but for example, 1.0 × 10 １０ atoms / cm ３ This tends to result in a metallic molybdenum film with lower electrical resistivity. In this specification, the content of each atom in the metallic molybdenum film is measured by secondary ion mass spectrometry (SIMS). In this specification, atoms / cm ３ means the density of the number of atoms (for example, tungsten atoms) present in a space.

[0051] To form a metallic molybdenum film having a silicon atom content within the above range, the metallic molybdenum film may be formed using, for example, hydrogen as a reducing agent, as described below. Alternatively, the metallic molybdenum film may be formed using at least one reducing agent selected from the group consisting of monomethylsilane, dimethylsilane, and trimethylsilane, although this is slightly inferior to the case where hydrogen is used.

[0052] The electrical conductivity of the metal molybdenum film at 25°C is preferably 7.0 x 10 ４ S / cm or more, more preferably 8.0 × 10 ４ S / cm or more, more preferably 1.0×10 ５ S / cm or more, particularly preferably 5.0 × 10 ５ S / cm or more, most preferably 1.0 x 10 ６ The upper limit is not particularly limited, but for example, 2.0 × 10７ S / cm or less. This tends to result in a metallic molybdenum film with lower electrical resistivity. In this specification, the electrical conductivity of the metallic molybdenum film is measured by a four-terminal method at room temperature (25°C). Note that the measured electrical conductivity also includes that of the substrate surface (e.g., Si), so the electrical conductivity of the metallic molybdenum film is calculated by subtracting the component of the substrate surface.

[0053] To form a metal molybdenum film having an electrical conductivity within the above range, the metal molybdenum film may be formed using, for example, a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass.

[0054] Although it varies depending on the semiconductor device structure used, the thickness (amount of film formation) of the metallic molybdenum film is, for example, preferably 0.1 nm to 10 μm, more preferably 1 nm to 2 μm. This tends to result in better electrical conductivity. In this specification, the thickness of the metallic molybdenum film means the thickness of the metallic molybdenum film formed on the substrate (the length in the normal direction from the substrate surface), and refers to the average value measured at multiple locations. In this specification, the thickness (amount of film formation) of the metallic molybdenum film is measured from a cross-sectional image taken with a scanning electron microscope (SEM).

[0055] Although the width of the metal molybdenum film varies depending on the semiconductor device structure used, when used as wiring in a semiconductor device, for example, the width is preferably 0.5 nm to 100 nm, more preferably 0.8 nm to 50 nm, and even more preferably 1 nm to 10 nm. Because the electrical resistivity of a metal film depends on its width (wiring width), particularly in narrow wiring widths of several nm to several tens of nm, even metal impurities such as tungsten have a higher electrical resistance than molybdenum, which may lead to an increase in electrical resistivity. Therefore, when the width of the metal molybdenum film is within the above-mentioned numerical range, the effects of the present disclosure tend to be more favorably achieved. In this specification, the width of the metal molybdenum film refers to the width of the metal molybdenum film formed on a substrate (the length in the thickness direction and perpendicular to the cross section perpendicular to the extension direction of the film), and refers to the average value measured at multiple locations. In this specification, the width of the metal molybdenum film is measured from a surface image taken with a scanning electron microscope (SEM).

[0056] In this specification, a substrate having a metal molybdenum film means that the metal molybdenum film is formed on the substrate, and the metal molybdenum film may be formed on a pattern formed on the substrate. In addition, another layer such as an underlayer may be present between the substrate and the metal molybdenum film. The metal molybdenum film is suitably used as wiring formed on the substrate.

[0057] The substrate (substrate on which the metal molybdenum film is formed) is not particularly limited, and for example, a silicon wafer is usually used, but is not limited thereto. ２ , SiN, AlO ｘ , HfO ｘ , ZrO ｘ, TiN, TaN, Ti, Co, Ru, Ta, W, and other semiconductor device substrates. The substrate may be surface-treated by silane coupling treatment, silazane treatment, organic thin film formation, SAM (self-assembled monolayer) treatment, or the like. The substrate may have a metal or metal oxide film. Specifically, the substrate may be a semiconductor device substrate having a metal or metal oxide film in its structure, or a substrate on which a metal or metal oxide is formed during the patterning process of the semiconductor device. Among these, the outermost surface of the substrate (the surface on which the metal molybdenum film is formed, i.e., the base) is preferably at least one selected from the group consisting of silicon and silicon-containing compounds, because it is widely used in the manufacture of semiconductor devices. Furthermore, the outermost surface of the substrate may be at least one selected from the group consisting of silicon, silicon-containing compounds, AlO ｘ , HfO ｘ , ZrO ｘ , TiN, TaN, Ti, Co, Ru, Ta and W (preferably at least one selected from the group consisting of silicon, silicon-containing compounds, TiN, TaN, Ti, Co, Ru, Ta and W).

[0058] The silicon may be polycrystalline silicon or single crystal silicon. The silicon and silicon-containing compounds may be used alone or in combination of two or more kinds.

[0059] Examples of silicon-containing compounds include silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, and silicon oxycarbonitride. These may be used alone or in combination of two or more. Silicon oxide is SiO ｘ (x is 1 or more and 2 or less), and is usually SiO ２ Silicon nitride is SiN ｘ (x is 0.3 or more and 9 or less), and is usually Si ３ N ４ Silicon oxynitride is Si ４ O ｘ N ｙ (x is 3 or more and 6 or less, y is 2 or more and 4 or less), for example, Si ４O ５ N ３ Silicon oxycarbide is a material in which 0.1% to 40% carbon is added to silicon oxide. Silicon oxycarbonitride is a material in which 0.1% to 30% carbon and 0.1% to 10% nitrogen are added to silicon oxide.

[0060] The shape and size of the substrate are not particularly limited.

[0061] <Method for manufacturing a substrate having a metallic molybdenum film> The method for manufacturing a substrate disclosed herein includes a film formation step of supplying a substrate with a gas containing a molybdenum precursor and a gas containing a reducing agent, and forming a metallic molybdenum film on the substrate, wherein the tungsten concentration in the molybdenum precursor is less than 100 ppb by mass. Because a molybdenum precursor with a low tungsten concentration is used, it is possible to form a metallic molybdenum film with a low tungsten atom content, and a substrate having a metallic molybdenum film with low electrical resistivity can be manufactured. Thus, the method for manufacturing a substrate disclosed herein is characterized by the use of a molybdenum precursor with a low tungsten concentration, and therefore the film formation apparatus and film formation method used are not particularly limited.

[0062] In this specification, the term "gas" refers to a gaseous state, and is a concept that includes a material that is gaseous at room temperature and pressure, a vaporized solid, and a vaporized liquid. In this specification, the term "molybdenum precursor" refers to a compound that can react with a reducing agent to form a metallic molybdenum film.

[0063] <<Molybdenum Precursor>> The substrate manufacturing method of the present disclosure is characterized by using a molybdenum precursor with a low tungsten concentration, so the molybdenum precursor of the present disclosure will first be described. The molybdenum precursor of the present disclosure is a molybdenum precursor with a tungsten concentration of less than 100 ppb by mass.

[0064] The tungsten concentration in the molybdenum precursor is less than 100 ppb by mass, preferably 90 ppb by mass or less, more preferably 80 ppb by mass or less, even more preferably 50 ppb by mass or less, and particularly preferably 10 ppb by mass or less. The lower limit is not particularly limited, but is, for example, 0.1 ppb by mass or more. This makes it possible to form a metallic molybdenum film with a lower tungsten atom content, which tends to enable the production of a substrate having a metallic molybdenum film with lower electrical resistivity. In this specification, the tungsten concentration and uranium concentration in the molybdenum precursor refer to the concentration of tungsten atoms and the concentration of uranium atoms in the molybdenum precursor, respectively, and are measured by inductively coupled plasma mass spectrometry (ICP-MS). The same applies to crude molybdenum precursors.

[0065] <<Film Forming Apparatus>> Next, an example of a film forming apparatus that can be used in the substrate manufacturing method of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram showing an example of a film forming apparatus that can be used in the substrate manufacturing method of the present disclosure.

[0066] As shown in FIG. 1 , the film forming apparatus 100 includes an airtight processing chamber 110, which includes a mounting portion 111 for horizontally supporting workpieces (wafers) 112, 113, and 114. The mounting portion 111 is made of a corrosion-resistant material, such as Ni. A heating means 160 is connected to the mounting portion 111 and the ceiling wall of the processing chamber 110, and a heater power supply (not shown) is connected to the heating means 160. A thermometer (not shown) is provided near the top surface of the mounting portion 111, and a signal from the thermometer is transmitted to a heater controller (not shown). The heater controller then sends a command to the heater power supply (not shown) in response to the signal from the thermometer, thereby controlling the heating of the heating means 160 and maintaining the workpieces (wafers) 112, 113, and 114 at a predetermined temperature. The mounting portion 111 can be raised and lowered by an elevation mechanism (not shown). The thermometer may be attached to measure the temperature of the inner wall of the processing vessel 110, and the heater control may control the wall of the processing vessel 110 to a predetermined temperature.

[0067] The molybdenum precursor supply unit 130 has a film-forming raw material tank (not shown) that contains a molybdenum precursor, which is a film-forming raw material. A heater (not shown) is provided around the film-forming raw material tank, and the film-forming raw material in the film-forming raw material tank may be heated to an appropriate temperature (for example, 50°C to 150°C) to vaporize the molybdenum precursor as needed.

[0068] The molybdenum precursor supply unit 130 supplies a molybdenum precursor gas into the processing vessel 110 via a valve 131, a flow rate adjusting unit 132, and pipes 121 and 133. The molybdenum precursor gas may be diluted with an inert gas.

[0069] The reducing agent supply unit 140 has a reducing agent tank (not shown) that stores a reducing agent, which is a film formation raw material. A heater (not shown) is provided around the reducing agent tank, and the reducing agent in the reducing agent tank may be heated to an appropriate temperature (for example, 70°C to 150°C) to vaporize the reducing agent as needed.

[0070] The reducing agent supply unit 140 supplies a reducing agent gas into the processing chamber 110 via a valve 141, a flow rate adjusting unit 142, and pipes 121 and 143. The reducing agent gas may be diluted with an inert gas.

[0071] The inert gas supply unit 150 supplies an inert gas into the processing chamber 110 via a valve 151 , a flow rate adjusting unit 152 , and pipes 121 and 153 .

[0072] A pipe 121 is connected to one sidewall of the processing vessel 110, and a molybdenum precursor gas, a reducing agent gas, and an inert gas are supplied into the processing vessel 110 via the pipe 121. A pressure gauge 122 is provided on the pipe 121. Based on the pressure measured by the pressure gauge 122, the valves 131, 141, and 151 are controlled by flow rate adjustment means 132, 142, and 152, thereby controlling the amounts of the molybdenum precursor gas, the reducing agent gas, and the inert gas supplied into the processing vessel 110.

[0073] A pipe 124 is connected to the other sidewall of the processing vessel 110. The pipe 124 is connected to a vacuum pump 126 via a valve 125, and exhaust is performed through a pipe 127 connected to the vacuum pump 126. By operating the vacuum pump 126, the inside of the processing vessel 110 can be reduced in pressure to a predetermined level. A pressure gauge 123 is provided on the pipe 124. The pressure inside the processing vessel 110 is controlled by controlling a valve 125 based on the pressure measured by the pressure gauge 123, etc.

[0074] The film forming apparatus 100 has a control unit (not shown) that controls each component, specifically, the valves, power supply, heater, pump, etc. This control unit includes a process controller equipped with a microprocessor (computer), a user interface, and a memory unit (all not shown). The process controller is electrically connected to and controls each component of the film forming apparatus 100. The user interface is connected to the process controller and includes a keyboard through which an operator inputs commands to manage each component of the film forming apparatus 100, and a display that visualizes and displays the operating status of each component of the film forming apparatus. A memory unit is also connected to the process controller and stores control programs for controlling various processes performed by the film forming apparatus 100 under the control of the process controller, control programs (i.e., process recipes) for causing each component of the film forming apparatus 100 to perform a predetermined process according to process conditions, various databases, etc. The process recipes are stored in a storage medium (not shown) in the storage unit. The storage medium may be a fixed medium such as a hard disk, or a portable medium such as a CD-ROM, DVD, or flash memory. Furthermore, the recipe may be transmitted from another device via, for example, an electric communication line.

[0075] Then, as necessary, a predetermined processing recipe is retrieved from the storage unit in response to an instruction from the user interface or the like and executed by the process controller, whereby the desired processing is performed in the film forming apparatus 100 under the control of the process controller.

[0076] <<Film Forming Step>> The method for producing a substrate having a metal molybdenum film according to the present disclosure includes a film forming step of supplying a gas containing a molybdenum precursor and a gas containing a reducing agent to a substrate to form a metal molybdenum film on the substrate.

[0077] The substrate is as described above. The film formation process may be performed using, for example, the film formation apparatus 100. The workpieces (wafers) 112, 113, and 114 are carried into the processing chamber 110, and placed on the mounting portion 111 inside the processing chamber 110, which has been heated to a predetermined temperature by the heating means 160. After the pressure is reduced to a predetermined vacuum level, a metal molybdenum film is formed (vapor-phase film formation) by the CVD method or the ALD method as follows.

[0078] (Film formation by chemical vapor deposition (CVD) method) First, by opening and closing a valve, an inert gas is supplied as a purge gas from the inert gas supply unit 150 into the processing vessel 110 to increase the pressure, and the temperature of the workpieces (wafers) 112, 113, and 114 on the mounting unit 111 is stabilized.

[0079] After the pressure inside the processing vessel 110 reaches a predetermined pressure, the inert gas is continued to be supplied into the processing vessel 110 from the inert gas supply unit 150, and further, the molybdenum precursor gas is supplied from the molybdenum precursor supply unit 130 and the reducing agent gas is supplied from the reducing agent supply unit 140 into the processing vessel 110. As a result, a product formed by reaction between the molybdenum precursor gas and the reducing agent gas is deposited on the surfaces of the workpieces (wafers) 112, 113, and 114, thereby forming a metallic molybdenum film.

[0080] After the deposition continues until the thickness of the metallic molybdenum film reaches a predetermined value, the valves 131 and 141 are closed to stop the supply of the molybdenum precursor gas and the reducing agent gas, and only the inert gas as a purge gas is supplied into the processing vessel 110 to purge the processing vessel 110. This completes the deposition by the CVD method. The thickness of the metallic molybdenum film at this time can be controlled by the deposition time.

[0081] (Film formation by atomic layer deposition (ALD) method in which a molybdenum precursor gas and a reducing agent gas are alternately supplied) First, as in the case of the CVD method, by opening and closing a valve, an inert gas is first supplied as a purge gas from the inert gas supply unit 150 into the processing vessel 110 to increase the pressure, and the temperature of the workpieces (wafers) 112, 113, and 114 on the mounting unit 111 is stabilized.

[0082] After the pressure inside the processing vessel 110 reaches a predetermined pressure, while the inert gas is still being supplied into the processing vessel 110 from the inert gas supply unit 150, a molybdenum precursor gas is further supplied into the processing vessel 110 from the molybdenum precursor supply unit 130 for a short period of time to adsorb the molybdenum precursor onto the surfaces of the workpieces (wafers) 112, 113, and 114 to be processed (molybdenum precursor gas supply step). Next, the valve 131 is closed to stop the supply of the molybdenum precursor gas, and the excess molybdenum precursor gas inside the processing vessel 110 is purged with the inert gas supplied into the processing vessel 110 from the inert gas supply unit 150 (purge step).

[0083] Next, while inert gas is being supplied into the processing vessel 110 from the inert gas supply unit 150, reducing agent gas is supplied into the processing vessel 110 from the reducing agent supply unit 140 for a short period of time, and reacted with the molybdenum precursor adsorbed on the workpieces (wafers) 112, 113, and 114 (reducing agent gas supply step). Next, the valve 141 is closed to stop the supply of reducing agent gas, and excess inert gas in the processing vessel 110 is purged with the inert gas supplied into the processing vessel 110 from the inert gas supply unit 150 (purge step).

[0084] A thin molybdenum unit film is formed by one cycle of the molybdenum precursor gas supply step, purging step, reducing agent gas supply step, and purging step. These steps are repeated multiple times to form a molybdenum metal film of a desired thickness. The thickness of the molybdenum metal film can be controlled by the number of times the cycle is repeated.

[0085] Examples of molybdenum precursors include molybdenum halides, molybdenum oxyhalides, molybdenum carbonyls, and MoCp２ N ｔ Bu, Mo (η ３ -C ３ H ５ ) ４ , Mo ２ O ３ , MoO ２ , tetrachloro(cyclopentadienyl)molybdenum, Mo(tBuN) ２ (NMe ２ ) ２ , Mo(NBu) ２ (StBu) ２ , (Me ２ N) ４ Mo, (iPrCp) ２ MoH ２ , Mo(NMe ２ ) ４ , Mo(NEt ２ ) ４ , Mo ２ (NMe ２ ) ６ , Mo(tBuN) ２ (NMe ２ ) ２ , Mo(NtBu) ２ (StBu) ２ , Mo(NtBu) ２ (iPr ２ AMD) ２ , Mo(thd) ３ , MoO ２ (acac) ２ , MoO ２ (thd) ２ , MoO ２ (iPr ２ AMD) ２ , Mo(Cp) ２ H ２ , Mo(iPrCp) ２ H ２ , Mo(η ６ -ethylbenzene) ２ These may be used alone or in combination of two or more. Among them, at least one selected from the group consisting of molybdenum halides, molybdenum oxyhalides, and molybdenum carbonyls is preferred, with molybdenum halides being more preferred. Furthermore, the molybdenum precursor may be MoOF ４may be removed.

[0086] The molybdenum halide is not particularly limited as long as it is a compound consisting of only molybdenum and halogen, and examples thereof include molybdenum fluoride, molybdenum chloride, molybdenum bromide, and molybdenum iodide. A specific example is MoF ６ , MoF ５ , MoF ４ , MoF ３ , MoCl ６ , MoCl ５ , MoCl ４ , MoCl ３ , MoBr ６ , MoBr ５ , MoBr ４ , MoBr ３ , MoI ６ , MoI ５ , MoI ４ , MoI ３ These may be used alone or in combination of two or more. Among them, MoF ６ , MoF ５ , MoCl ５ is preferred, and MoF ６ is more preferred.

[0087] The molybdenum oxyhalide is not particularly limited as long as it is a compound consisting of only molybdenum, halogen, and oxygen. Examples thereof include molybdenum oxyfluoride, molybdenum oxychloride, molybdenum oxybromide, and molybdenum oxyiodide. Specific examples include MoOF ４ , MoO ２ Cl ２ , MoO ２ F ２ , MoOCl ４ , MoOCl ３ These may be used alone or in combination of two or more. Among them, MoOF ４ , MoO ２ Cl ２ is preferred.

[0088] The molybdenum carbonyl compound is not particularly limited as long as it is a compound having molybdenum and a carbonyl group, and examples thereof include Mo(CO) ６ , Mo(η６ -C ６ H ６ ) (CO) ３ , MoCp(η ３ -C ３ H ５ ) (CO) ２ , Mo(η ６ -C ６ H ３ (CH ３ ) ３ ) (CO) ３ , MoCp(CO) ２ (NO), etc. These may be used alone or in combination of two or more.

[0089] MoF ６ As shown in Table 1, Mo(CO) ６ and MoCl ５ It has a higher vapor pressure than MoF, and is easy to purify and handle (e.g., stable supply to a film forming device). ６ can be deposited at a relatively low temperature of 200 to 400°C. Therefore, MoF is used as a molybdenum precursor. ６ is preferred.

[0090] Examples of reducing agents include hydrogen, monomethylsilane, dimethylsilane, trimethylsilane, monofluorosilane, difluorosilane, trifluorosilane, silane, disilane, borane, diborane, germane, ammonia, and phosphine. These may be used alone or in combination of two or more. Among them, at least one selected from the group consisting of hydrogen, monomethylsilane, dimethylsilane, trimethylsilane, monofluorosilane, difluorosilane, trifluorosilane, silane, and disilane is preferred, at least one selected from the group consisting of hydrogen, monomethylsilane, dimethylsilane, trimethylsilane, monofluorosilane, difluorosilane, and trifluorosilane is more preferred, at least one selected from the group consisting of hydrogen, monomethylsilane, dimethylsilane, and trimethylsilane is particularly preferred, and hydrogen is most preferred.

[0091] The gas containing a molybdenum precursor and the gas containing a reducing agent may further contain an inert gas. Note that, in this specification, the concept of supplying a gas containing a molybdenum precursor and a gas containing a reducing agent includes the case where a molybdenum precursor gas and a reducing agent gas are separately supplied, as in the ALD method described above.

[0092] The inert gas is not particularly limited as long as it is a gas that does not participate in the reaction between the molybdenum precursor and the reducing agent, and examples thereof include nitrogen, argon, helium, etc. These may be used alone or in combination of two or more. Among these, nitrogen gas is preferred.

[0093] The pressure during the film formation process (the pressure of the gas in contact with the substrate, the pressure of the gas in the processing chamber) is preferably 0.1 Pa to 10 kPa, more preferably 0.1 Pa to 5 kPa.

[0094] In the film formation step, the temperature of the substrate is preferably 25° C. to 800° C., more preferably 200° C. to 600° C., and even more preferably 250° C. to 550° C. Furthermore, since the film formation reaction proceeds more easily at higher temperatures, it is preferable to set the temperature of the substrate higher than the temperature of the wall of the processing vessel in order to cause the film formation reaction to proceed preferentially on the substrate.

[0095] In the film formation process, the amount of inert gas supplied to the substrate is not particularly limited. This is because, for example, the inert gas is continuously supplied until the conditions in the processing chamber become stable. On the other hand, the amounts of the molybdenum precursor (molybdenum precursor gas) and the reducing agent (reducing agent gas) supplied to the substrate are not particularly limited as long as they are capable of reacting with each other on the substrate. However, when the molybdenum precursor gas and the reducing agent gas are supplied simultaneously, the volume ratio of the molybdenum precursor (molybdenum precursor gas) to the reducing agent (reducing agent gas) (supply amount (parts by volume) of the molybdenum precursor (molybdenum precursor gas):supply amount (parts by volume) of the reducing agent (reducing agent gas)) is preferably 1:3 to 1:10,000, more preferably 1:5 to 1:1,000.

[0096] In the film formation step, the total content of the molybdenum precursor (molybdenum precursor gas), reducing agent (reducing agent gas), and inert gas in the total amount of gas supplied to the substrate (100% by volume) is preferably 60% by volume or more, more preferably 80% by volume or more, even more preferably 90% by volume or more, particularly preferably 95% by volume or more, and may be 100% by volume.

[0097] The molybdenum precursor gas and the reducing agent gas may be gases containing 100% by volume of each, or may be gases diluted with an inert gas, etc. The concentrations of the molybdenum precursor and the reducing agent in the gas are not particularly limited, but the higher the concentrations, the more rapidly a metallic molybdenum film can be formed.

[0098] The time for performing the film formation step can be appropriately set depending on the amount of the metal molybdenum film to be formed.

[0099] In the method for manufacturing a substrate according to the present disclosure, steps other than the film formation step may be carried out as necessary to the extent that the effects of the present disclosure are not impaired.

[0100] In the method for producing a substrate according to the present disclosure, the molybdenum precursor is MoF ６ and the MoF ６ The reaction between the reducing agent and the molybdenum precursor is preferably carried out so that the ΔG of the reaction is within the range of −570 to −280 kJ / mol. If ΔG is greater than −280 kJ / mol, nuclei cannot be sufficiently generated on the substrate surface unless there is a nucleation layer on the substrate that reacts with the molybdenum precursor, and depending on the type of substrate, a sufficient molybdenum film may not be formed. If ΔG is less than −570 kJ / mol, the reactivity may be too high and damage the substrate may be caused. However, by carrying out the reaction so that ΔG is within the range of −570 to −280 kJ / mol, a molybdenum film can be more suitably formed without substrate selectivity, i.e., with minimal damage, on any substrate. In this way, by carrying out the reaction so that ΔG is within the range of −570 to −280 kJ / mol, a molybdenum film can be more suitably formed with minimal damage on any substrate, even without providing a nucleation layer on the substrate surface.

[0101] The ΔG is preferably −570 to −280 kJ / mol, more preferably −500 to −280 kJ / mol, and even more preferably −479 to −283 kJ / mol. This makes it possible to more suitably form a metal molybdenum film on any substrate with less damage. In this specification, ΔG (Gibbs free energy) is defined as the ratio of the MoF ６ +This is a value calculated for the reaction of reducing agent → Mo using the Reaction Equations Module of HSC Chemistry 8 (manufactured by Autotec).

[0102] The MoF in the film formation step ６ As an example of a method for carrying out the reaction of the molybdenum precursor with the reducing agent so that the ΔG of the reaction is in the range of −570 to −280 kJ / mol, ６ wherein the reducing agent is hydrogen, and the substrate is heated to 350° C. or higher in the film-forming step. ６ When the reducing agent is hydrogen, if the substrate is heated to a temperature lower than 350°C in the film formation step, the nucleation reaction may not proceed sufficiently on the surface of the substrate, and a molybdenum metal film may not be formed sufficiently on any substrate. However, when the molybdenum precursor is MoF ６ When the reducing agent is hydrogen, the substrate is heated to 350° C. or higher in the film formation step, thereby forming MoF ６ The reaction between MoF and hydrogen becomes a gas phase reaction, and nucleation occurs more favorably in the gas phase, so dependency on the substrate surface is reduced and a metal molybdenum film can be more favorably formed on any substrate with less damage. ６ The reaction of MoF with hydrogen is a gas phase reaction. ６ This can more suitably suppress damage to the substrate caused by the reaction.

[0103] The molybdenum precursor is MoF ６When the reducing agent is hydrogen, the substrate temperature in the film formation step is preferably 350° C. to 600° C., more preferably 350° C. to 550° C., and even more preferably 350° C. to 500° C. This makes it possible to more suitably form a metal molybdenum film on any substrate with less damage.

[0104] The molybdenum precursor is MoF ６ The reducing agent is hydrogen. When the film is formed by the CVD method, MoF ６ , hydrogen partial pressure ratio (MoF ６ / hydrogen) is preferably 1 / 5 to 1 / 100, and more preferably 1 / 5 to 1 / 50. This makes it possible to more suitably form a metal molybdenum film on any substrate with less damage.

[0105] The MoF in the film formation step ６ In another example of the method for reacting the molybdenum precursor with the reducing agent so that the ΔG of the reaction is in the range of −570 to −280 kJ / mol, the molybdenum precursor may be MoF ６ and the reducing agent is at least one selected from the group consisting of monomethylsilane, dimethylsilane, and trimethylsilane. ６ and the reducing agent is at least one selected from the group consisting of monomethylsilane, dimethylsilane, and trimethylsilane, the reactivity of the reduction reaction becomes appropriate, and therefore a metal molybdenum film can be more suitably formed on any substrate with less damage, even without providing a nucleation layer on the surface of the substrate.

[0106] The molybdenum precursor is MoF ６ and the reducing agent is at least one selected from the group consisting of monomethylsilane, dimethylsilane, and trimethylsilane, the temperature of the substrate in the film formation step may be lower than that in the case where hydrogen is used as the reducing agent, and is preferably 20°C to 200°C, more preferably 25°C to 150°C, and even more preferably 30°C to 120°C.

[0107] As described above, the molybdenum precursor is MoF６ wherein the reducing agent is hydrogen, and the substrate is heated to 350° C. or higher in the film-forming step; and the molybdenum precursor is MoF ６ and the reducing agent is at least one selected from the group consisting of monomethylsilane, dimethylsilane, and trimethylsilane; or the molybdenum precursor is MoF ６ and the MoF ６ and the reducing agent so that ΔG of the reaction is in the range of −570 to −280 kJ / mol, it is possible to more suitably form a metal molybdenum film on any substrate with less damage without providing a nucleation layer on the surface of the substrate. Therefore, it is possible to form a metal molybdenum film on the outermost surface of the substrate with less damage to the substrate. ｘ , HfO ｘ , ZrO ｘ A metal molybdenum film can be suitably formed using at least one selected from the group consisting of TiN, TaN, Ti, Co, Ru, Ta, and W (preferably at least one selected from the group consisting of silicon, silicon-containing compounds, TiN, TaN, Ti, Co, Ru, Ta, and W). Here, the silicon and silicon-containing compounds are as described above, including preferred embodiments.

[0108] When the interface between the metal molybdenum film and the outermost surface of the substrate is observed at 50,000 magnifications, the ten-point average roughness is preferably 20 nm or less, more preferably 10 nm or less, even more preferably 5 nm or less, and particularly preferably 2 nm or less. Since damage to the substrate can be suppressed, the outermost surface of the substrate can be maintained smooth. The ten-point average roughness can be measured by the method described in the Examples.

[0109] In the film formation process, it is preferable that the oxygen concentration in the reaction system (oxygen concentration in the gas in the processing vessel) be 10 volume ppm or less. This can further reduce damage to the substrate and the oxygen atom content in the metallic molybdenum film, making it possible to more suitably form a metallic molybdenum film with less damage on any substrate without providing a nucleation layer on the surface of the substrate. In this specification, the oxygen concentration in the reaction system is measured by gas chromatography.

[0110] <Method for producing a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass> The method for producing a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass according to the present disclosure includes a removal step of removing tungsten from a crude molybdenum precursor having a tungsten concentration of more than 100 ppb by mass using at least one method selected from the group consisting of distillation and adsorption using a solid metal fluoride.

[0111] As described above, the present inventors have discovered that by using a molybdenum precursor having a low tungsten concentration, it is possible to form a metallic molybdenum film having a low tungsten atom content, and to produce a substrate having a metallic molybdenum film with low electrical resistivity. The molybdenum precursor of the present disclosure, which is a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass, is a molybdenum precursor that could only be conceived by arriving at the findings discovered by the present inventors. Similarly, the method for producing a molybdenum precursor of the present disclosure having a tungsten concentration of less than 100 ppb by mass is a method for producing a molybdenum precursor that could only be conceived by arriving at the findings discovered by the present inventors.

[0112] The method for producing a molybdenum precursor according to the present disclosure is characterized by carrying out a removal step in which tungsten is removed from a crude molybdenum precursor having a tungsten concentration of more than 100 ppb by mass by at least one method selected from the group consisting of distillation and adsorption using a solid metal fluoride. Either distillation or adsorption using a solid metal fluoride may be carried out alone, or both may be carried out together. When both are carried out together, either one may be carried out first. Among these, adsorption using a solid metal fluoride is preferred.

[0113] The distillation and adsorption using a solid metal fluoride carried out in the removal step will be described below.

[0114] <<Distillation>> Distillation is a method of heating a crude molybdenum precursor to vaporize it, and then condensing it to separate the tungsten-containing compound and the molybdenum precursor by utilizing the difference in boiling points. Known distillation methods can be used, and for example, distillation treatments can be carried out that include one or more selected from the group consisting of batch distillation, continuous distillation, atmospheric distillation, reduced-pressure distillation (vacuum distillation), pressure distillation, simple distillation, and precision distillation. These methods may be used alone or in combination of two or more. These methods may also be carried out repeatedly.

[0115] <<Adsorption Using Solid Metal Fluoride>> Solid metal fluorides selectively adsorb tungsten and uranium over molybdenum, so that tungsten and uranium contained in the crude molybdenum precursor are suitably removed by the solid metal fluoride. Here, molybdenum refers to MoF ６ Molybdenum precursors such as WF ６ Tungsten-containing compounds such as UF ６ This refers to uranium-containing compounds such as:

[0116] The solid metal fluoride is not particularly limited as long as it is a metal fluoride, and examples thereof include alkali metal fluorides, alkaline earth metal fluorides, etc. These may be used alone or in combination of two or more. Among these, at least one selected from the group consisting of alkali metal fluorides and alkaline earth metal fluorides is preferred, and alkali metal fluorides are more preferred.

[0117] The alkali metal fluoride is not particularly limited as long as it is a fluoride of an alkali metal, and examples thereof include sodium fluoride, lithium fluoride, potassium fluoride, etc. These may be used alone or in combination of two or more. Of these, sodium fluoride is preferred.

[0118] The alkaline earth metal fluoride is not particularly limited as long as it is a fluoride of an alkaline earth metal, and examples thereof include calcium fluoride, barium fluoride, magnesium fluoride, etc. These may be used alone or in combination of two or more.

[0119] The temperature of the solid metal fluoride is preferably 25° C. to 300° C., more preferably 50° C. to 200° C., and even more preferably 100° C. to 150° C. When the temperature of the metal fluoride is 100° C. or higher, it tends to be possible to more suitably remove tungsten.

[0120] The contact time between the solid metal fluoride and the crude molybdenum precursor varies depending on the temperature of the metal fluoride, but is preferably 0.1 to 60 seconds, more preferably 1 to 60 seconds, and even more preferably 1.5 to 30 seconds.

[0121] In the adsorption using a solid metal fluoride, for example, a crude molybdenum precursor gas may be brought into contact with the solid metal fluoride, and specifically, the crude molybdenum precursor gas may be passed through a tube filled with the solid metal fluoride.

[0122] <<Crude Molybdenum Precursor>> The crude molybdenum precursor is not particularly limited as long as it has a tungsten concentration of more than 100 ppb by mass, and is similar to the molybdenum precursor described in <Method for producing a substrate having a metal molybdenum film>, including preferred embodiments, except for the impurity concentration.

[0123] The tungsten concentration in the crude molybdenum precursor is preferably more than 100 ppb by mass and not more than 50% by mass, more preferably 1 ppm by mass to 1% by mass, and even more preferably 10 ppm by mass to 0.1% by mass. Even if the tungsten concentration in the crude molybdenum precursor is within the above range, a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass can be produced by the removal step.

[0124] The uranium concentration in the crude molybdenum precursor is preferably more than 100 ppb by mass and not more than 50% by mass, more preferably 1 ppm by mass to 0.1% by mass, and even more preferably 10 ppm by mass to 100 ppm by mass. Even if the uranium concentration in the crude molybdenum precursor is within the above range, a molybdenum precursor having a uranium concentration of less than 100 ppb by mass can be produced by the removal step.

[0125] <<Molybdenum Precursor Produced>> The molybdenum precursor produced by the method for producing a molybdenum precursor according to the present disclosure has a tungsten concentration of less than 100 ppb by mass, and is similar to the molybdenum precursor described in <<Molybdenum Precursor>>, including preferred embodiments thereof.

[0126] In the removal step, uranium is also removed together with tungsten. Therefore, the uranium concentration in the produced molybdenum precursor is preferably less than 100 ppb by mass, more preferably 50 ppb by mass or less, and even more preferably 10 ppb by mass or less. The lower limit is not particularly limited, but is, for example, 0.1 ppb by mass or more.

[0127] In the method for producing a molybdenum precursor according to the present disclosure, steps other than the removal step may be carried out as necessary to the extent that the effects of the present disclosure are not impaired.

[0128] Examples that more specifically disclose embodiments of the present disclosure are given below, but the present disclosure is not limited to these examples.

[0129] First, each evaluation method will be described.

[0130] [Gas analysis] Molybdenum hexafluoride (MoF ６The concentrations of tungsten (W) and uranium (U) in the gas were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). ６ ) concentrations were analyzed by Fourier transform infrared spectroscopy (FT-IR).

[0131] [Analysis of Metallic Molybdenum Film] The thickness (amount of film formed) of the metallic molybdenum film was measured from a cross-sectional image taken with a scanning electron microscope (SEM). The content of each atom in the metallic molybdenum film was measured by secondary ion mass spectrometry (SIMS). The electrical conductivity of the metallic molybdenum film was measured by a four-terminal method at room temperature (25°C). The electrical conductivity measured included the material (Si, SiO) of the substrate surface. ２ The electrical conductivity of the metal molybdenum film was calculated by subtracting the amount of the substrate surface.

[0132] (Preparation of Molybdenum Precursor (1)) According to the schematic diagram shown in FIG. 2 and Tables 2 and 3, W (tungsten) was added to a molybdenum precursor at a concentration of 50 ppm by mass (=5.0×10 ４ MoF (mass ppb) ６ The gas was passed through the NaF-filled tube at a predetermined temperature and time. ６ W concentration in gas, MoF ６ MoF contained in gas ６ The concentration was analyzed. A SUS tube with an outer diameter of 1 inch was used as the NaF-filled tube, and MoF ６ The contact pressure was 20 kPa (abs).

[0133]

[0134]

[0135] Tables 2 and 3 show that tungsten can be removed by adsorption using a solid metal fluoride, and that a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass can be produced from a crude molybdenum precursor having a tungsten concentration of more than 100 ppb by mass.

[0136] From Table 2, it was found that the W concentration can be reduced to 20 mass ppb or less by setting the contact temperature (temperature of metal fluoride) to 50°C or higher, and that the W concentration can be reduced to 10 mass ppb or less by setting the contact temperature (temperature of metal fluoride) to 100°C or higher. Note that in Example 1-5, in which the contact temperature (temperature of metal fluoride) was set to 300°C, MoF ６ It was found that the yield was reduced when NaF was adsorbed onto the catalyst.

[0137] From Table 3, it is clear that, when the contact temperature is 100° C., a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass can be produced from a crude molybdenum precursor having a tungsten concentration of more than 100 ppb by mass when the contact time between the solid metal fluoride and the crude molybdenum precursor exceeds 1 second. On the other hand, when the contact temperature is 100° C., a sufficient W reduction effect cannot be obtained when the contact time between the solid metal fluoride and the crude molybdenum precursor is 1 second or less.

[0138] (Preparation of Molybdenum Precursor (2)) According to the schematic diagram shown in FIG. 2 and Table 4, MoF containing 1000 ppb by mass of U (uranium) was prepared. ６ The gas was passed through the NaF-filled tube at a predetermined temperature and time. ６ U concentration in gas, MoF ６ MoF contained in gas ６ The concentration was analyzed. A SUS tube with an outer diameter of 1 inch was used as the NaF-filled tube, and MoF ６ The contact pressure was 20 kPa (abs).

[0139]

[0140] Table 4 shows that uranium can be removed by adsorption using a solid metal fluoride, and that a molybdenum precursor having a uranium concentration of less than 100 ppb by mass can be produced from a crude molybdenum precursor having a uranium concentration of more than 100 ppb by mass.

[0141] (Preparation of Molybdenum Precursor (3)) The molybdenum precursor (MoF) having a tungsten concentration of 10 mass ppb or less prepared in Example 1-2 was used. ６ ) to WF ６was appropriately added to prepare molybdenum precursors (MoF) with various tungsten concentrations. ６ ) was prepared and used in the following metal molybdenum film deposition experiment.

[0142] (Deposition of Metal Molybdenum Film by Chemical Vapor Deposition (CVD) Method) A metal molybdenum film was formed on a wafer substrate using the film formation apparatus shown in FIG. 1. The specific steps are as follows: The wafer substrate was placed in a processing chamber, and N ２ The temperature was raised under gas flow, and the substrate temperature was adjusted to 250° C. After the substrate temperature was stabilized, MoF ６ Gas / reducing agent gas / N ２ The gas was circulated in the processing vessel for the film formation time shown in Table 5, and film formation was carried out under the following conditions: Gas pressure in the processing vessel: 2 kPa Supply amount of molybdenum precursor (volume parts) / Supply amount of reducing agent (volume parts): 1 / 5 to 1 / 50 Next, MoF ６ Gas / reducing agent gas / N ２ After the gas flow into the processing vessel was completed, the processing vessel was purged with N ２ The temperature was lowered to room temperature under gas flow. A Ni hot-wall type film-forming chamber was used as the processing vessel. The wafer substrate was a single-crystal Si substrate with a SiO 2 layer between the surface Si layer. ２ An SOI (Silicon On Insulator) substrate (c-Si 100 nm / SiO ２ 100 nm / Si) was used.

[0143]

[0144] Table 5 shows that the production methods of the examples, which include a film formation step of supplying a gas containing a molybdenum precursor and a gas containing a reducing agent to a substrate and forming a metallic molybdenum film on the substrate, and in which the tungsten concentration in the molybdenum precursor is less than 100 ppb by mass, use a molybdenum precursor with a low tungsten concentration, and therefore make it possible to form a metallic molybdenum film with a low tungsten atom content, and to produce substrates having a metallic molybdenum film with high purity and low electrical resistivity.

[0145] Among the results shown in Table 5, the results when the reducing agent was H ２The results for the film formation time of 10 minutes are summarized in Table 6.

[0146]

[0147] Table 6 shows that there is a significant difference between the tungsten concentrations in the molybdenum precursors of 90 ppb by mass and 100 ppb by mass.

[0148] (Deposition of Metal Molybdenum Film by Atomic Layer Deposition (ALD) Method) A metal molybdenum film was formed on a wafer substrate using the film formation apparatus shown in FIG. 1. The specific steps are as follows: The wafer substrate was placed in a processing chamber, and N ２ The temperature was raised under gas flow, and the substrate temperature was adjusted to 130° C. After the substrate temperature was stabilized, N ２ Under gas flow, MoF ６ Gas supply / N ２ Gas purge / reducing agent gas supply / N ２ Gas purging was performed for 3, 60, 12, and 60 seconds, respectively, and 100 cycles were performed. The total film formation time for 100 cycles was 225 minutes. Gas pressure in the processing chamber: 2 kPa. After the film formation process was completed, the processing chamber was purged with N ２ The temperature was lowered to room temperature under gas flow. The processing vessel and substrate were the same as those used in the CVD method.

[0149]

[0150] Table 7 shows that in the production methods of the examples in which the tungsten concentration in the molybdenum precursor is less than 100 ppb by mass, a molybdenum precursor with a low tungsten concentration is used, making it possible to form a molybdenum metal film with a low tungsten atom content, and to produce substrates having a molybdenum metal film with high purity and low electrical resistivity.

[0151] In the following experiments, the molybdenum precursor was MoF prepared in Example 1-2, which had a tungsten concentration of 10 mass ppb or less. ６In all subsequent experiments, the oxygen concentration in the treatment vessel during testing was set to 10 ppm by volume or less. The oxygen concentration in the gas was measured using a gas chromatograph (Shimadzu Corporation GC-2010PlusAF + BID 2010Plus).

[0152] (Deposition of Metal Molybdenum Film by Chemical Vapor Deposition (CVD) Method) A metal molybdenum film was deposited on a wafer substrate using the deposition apparatus shown in Figure 1. The specific steps are as follows: A wafer substrate (the uppermost surface of which is made of single-crystal Si, SiO ２ , TiN, TaN, Ti, Co, Ru, Ta, W) was placed in a processing vessel (a hot-wall type film-forming chamber made of Ni), and N ２ The temperature was raised under gas flow, and the substrate temperature was adjusted to 350 to 500°C. After the substrate temperature was stabilized, MoF ６ Gas / reducing agent gas / N ２ The gas was circulated in the processing vessel for the film formation time shown in Table 8, and film formation was carried out under the following conditions: gas pressure in the processing vessel: 4.5 kPa; supply amount of molybdenum precursor (volume parts) / supply amount of reducing agent (volume parts): 1 / 100. Next, MoF ６ Gas / reducing agent gas / N ２ After the gas flow into the processing vessel was completed, the processing vessel was purged with N ２ The temperature was lowered to room temperature under gas flow. The oxygen concentration in the processing vessel during the test was 10 volume ppm or less. Note that the film formation temperature and film formation pressure in the table refer to the substrate temperature and gas pressure in the processing vessel, respectively. Conditions not specified in this section were the same as those in Example 1.

[0153]

[0154] From Table 8, MoF ６ and H ２ The film formation using the above method can be performed under the condition of a film formation temperature of 350 to 500°C without providing a nucleation layer on the surface of the substrate, and can be performed on any base material (Si, SiO ２ It was possible to form a metal molybdenum film on various substrates (TiN, TaN, Ti, Co, Tu, Ta, W). It was also confirmed that the content of oxygen and fluorine atoms in the molybdenum film was low, and that a high-purity film could be formed.

[0155] In addition, the cross section of the substrate after film formation was observed with a scanning electron microscope (SEM), and the interface between the base material and the metallic molybdenum film was observed at 50,000 magnifications, and the ten-point average roughness of the interface was calculated. The ten-point average roughness was calculated by adding the average of the absolute values ​​of the elevations of the five highest peaks from the mean line of the interface and the average of the absolute values ​​of the elevations of the five lowest valleys within a reference length of approximately 1.9 μm. As a result, in Examples 101 to 127, the ten-point average roughness of the base material after film formation (the ten-point average roughness when the interface between the metallic molybdenum film and the outermost surface of the substrate was observed at 50,000 magnifications) was 2 nm or less.

[0156]

[0157] Table 9 shows SiO ２ The results of the electrical conductivity of the metal molybdenum film formed on the substrate are shown below (room temperature: 25° C.), and it was confirmed that the metal molybdenum film had low electrical resistivity.

[0158] (MoF ６ Influence of film formation temperature on film formation mode in Mo film formation using MoF (Reference Example 1) ６ It is assumed that the film formation mode differs between film formation temperatures of 300°C or less and 350°C or more. Figure 3 shows the MoF film formation when a Si substrate is used under film formation temperatures of 300°C and 400°C. ６ The relationship between the Mo partial pressure and the Mo film formation rate is shown in the graph.

[0159] From Figure 3, it can be seen that the film formation at 300°C is an upward convex curve, whereas the film formation at 400°C is a downward convex quadratic curve. This characteristic indicates that the film formation at 300°C is a surface reaction on the substrate, whereas the film formation at 400°C is characterized by a reaction on the gas phase side (gas phase reaction). At the film formation temperature of 300°C, MoF ６ Even if the partial pressure of MoF increases, the deposition rate does not increase beyond a certain value, indicating that the adsorbed species on the substrate surface are saturated. It is clear that the deposition rate is determined by the surface reaction. On the other hand, in the deposition at a deposition temperature of 400°C, ６The deposition rate increased quadratically with increasing partial pressure of molybdenum, indicating that the adsorbed species on the substrate surface did not affect the deposition rate. This deposition method, characterized by a reaction in the gas phase, enabled the deposition of a molybdenum metal film directly on any substrate.

[0160] (Deposition of Metal Molybdenum Film, Deposition by Atomic Layer Deposition (ALD) Method) A metal molybdenum film was deposited on a wafer substrate in accordance with the conditions shown in Tables 10 and 11 and the same procedure as in Example 7 shown in Table 7.

[0161]

[0162]

[0163] From Tables 10 and 11, monomethylsilane (SiH ３ Me), dimethylsilane (SiH ２ Me ２ ), trimethylsilane (SiHMe ３ In the film formation using an arbitrary underlayer material (Si, SiO) under the condition of a film formation temperature of 30 to 120°C, even if a nucleation layer is not provided on the surface of the substrate, ２ , TiN, TaN, Ti, Co, Tu, Ta, W). Furthermore, in Examples 128 to 181, the ten-point mean roughness of the base material after film formation (ten-point mean roughness when observing the interface between the metal molybdenum film and the outermost surface of the substrate at 50,000 magnifications) was 2 nm or less. Furthermore, it was confirmed that the content of fluorine atoms and silicon atoms in the molybdenum film was low, and a high-purity film could be formed. In particular, by using monomethylsilane or the like as a reducing agent, silane (SiH ４ ) and disilane (Si ２ H ６The silicon atom content in the metallic molybdenum film was reduced compared to Examples 7 and 8, which used a reducing agent. Although the principle behind this is unclear, it is believed that the silicon atoms in the metallic molybdenum film originate from the reducing agent, and that the intermediate species having Mo and Si generated during film formation may become unstable due to the inclusion of methyl groups, making them less likely to be included in the metallic molybdenum film. Furthermore, since no localized silicon atoms were observed when depth analysis of the metallic molybdenum film was performed, it is believed that the silicon atoms are diffused and present in the metallic molybdenum film.

[0164]

[0165] Table 12 shows SiO ２ The results of the electrical conductivity of the metal molybdenum film formed on the substrate are shown below (room temperature: 25° C.), and it was confirmed that the metal molybdenum film had low electrical resistivity.

[0166] Table 13 shows the results of "MoF ６ The results obtained by calculating the ΔG [kJ / mol] value for the reaction "+reducing agent → Mo" at each temperature are shown.

[0167]

[0168] From Table 13, H ２ When focusing on the reaction using SiH as a reducing agent, it is assumed that the film formation reaction is characterized by the reaction occurring in the gas phase when ΔG is -280 kJ / mol or less. ４ and Si ２ H ６ The ΔG value of SiH is very small, ranging from -1100 to -571 kJ / mol. ２ Me ２ In the case of MoF, ΔG is −500 to −447 kJ / mol at 0 to 200°C. ６ It has been found that by carrying out the reaction between the reducing agent and the cation exchanger so that the ΔG of the reaction is in the range of not more than -280 kJ / mol and not less than -570 kJ / mol, a metal molybdenum film can be suitably formed on any substrate with minimal damage.

[0169] REFERENCE SIGNS LIST 100 Film forming apparatus 110 Processing vessel 111 Mounting section 112, 113, 114 Object to be processed (wafer) 122, 123 Pressure gauge 126 Vacuum pump 130 Molybdenum precursor supply section 140 Reducing agent supply section 150 Inert gas supply section 160 Heating means 125, 131, 141, 151 Valve 132, 142, 152 Flow rate adjusting means 121, 124, 127, 133, 143, 153 Piping

Claims

1. The content of tungsten atoms in the film is 1.0 x 10 １６ atoms / cm ３ A substrate having a metal molybdenum film, 2. The electrical conductivity of the metal molybdenum film at 25° C. is 7.0×10 ４ 2. The substrate according to claim 1, wherein the resistivity is 1.0 S / cm or more.

3. A method for producing a substrate having a metallic molybdenum film, comprising: a film formation step of supplying a gas containing a molybdenum precursor and a gas containing a reducing agent to a substrate and forming a metallic molybdenum film on the substrate, wherein the tungsten concentration in the molybdenum precursor is less than 100 ppb by mass.

4. The method for producing a substrate according to claim 3, wherein a gas containing a molybdenum precursor and a gas containing a reducing agent are supplied simultaneously in the film forming step.

5. The method for producing a substrate according to claim 3, wherein in the film forming step, a gas containing a molybdenum precursor and a gas containing a reducing agent are supplied alternately.

6. The molybdenum precursor is selected from the group consisting of molybdenum halides, molybdenum oxyhalides, molybdenum carbonyls, MoCp ２ N ｔ Bu, Mo (η ３ -C ３ H ５ ) ４ , Mo ２ O ３ , MoO ２ , tetrachloro(cyclopentadienyl)molybdenum, Mo(tBuN) ２ (NMe ２ ) ２ , Mo(NBu) ２ (StBu) ２ , (Me ２ N) ４ Mo, (iPrCp) ２ MoH ２ , Mo(NMe ２ ) ４ , Mo(NEt ２ ) ４ , Mo ２ (NMe ２ ) ６ , Mo(tBuN) ２ (NMe ２ ) ２ , Mo(NtBu) ２ (StBu) ２ , Mo(NtBu) ２ (iPr ２ A.M.D. ２ , Mo(thd) ３ , MoO ２ (acac) ２ , MoO ２ (thd) ２ , MoO ２ (iPr ２ A.M.D. ２ , Mo(Cp) ２ H ２ , Mo(iPrCp) ２ H ２ , and Mo(η ６ -Ethylbenzene) ２ The method for producing a substrate according to claim 3, wherein the at least one selected from the group consisting of:

7. The molybdenum precursor is MoF ６ The method for producing a substrate according to claim 3, 8. The method for producing a substrate according to claim 3 or 4, wherein the tungsten concentration in the molybdenum precursor is 10 ppb by mass or less.

9. The method for manufacturing a substrate according to claim 3 or 4, wherein the temperature of the substrate is 25° C. or higher and 800° C. or lower in the film forming step.

10. The method for manufacturing a substrate according to claim 3 or 4, wherein in the film-forming step, the outermost surface of the substrate is made of at least one material selected from the group consisting of silicon and silicon-containing compounds.

11. The method for manufacturing a substrate according to claim 3 or 4, wherein the pressure during the film formation step is 0.1 Pa to 10 kPa.

12. The method for manufacturing a substrate according to claim 3 or 4, wherein the reducing agent is at least one selected from the group consisting of hydrogen, monomethylsilane, dimethylsilane, trimethylsilane, monofluorosilane, difluorosilane, trifluorosilane, silane, disilane, borane, diborane, germane, ammonia and phosphine.

13. The method for manufacturing a substrate according to claim 3 or 4, wherein the gas includes an inert gas.

14. The molybdenum precursor is MoF ６ In the film formation step, ６ The method for producing a substrate according to claim 3, wherein the reaction between said reducing agent and said ruthenium oxide is carried out so that ΔG of the reaction is within the range of −570 to −280 kJ / mol.

15. The molybdenum precursor is MoF ６ 4. The method for manufacturing a substrate according to claim 3, wherein the reducing agent is hydrogen, and the substrate is heated to 350° C. or higher in the film forming step.

16. The molybdenum precursor is MoF ６ 4. The method for producing a substrate according to claim 3, wherein the reducing agent is at least one selected from the group consisting of monomethylsilane, dimethylsilane, and trimethylsilane.

17. In the film forming process, the outermost surface of the substrate is formed of silicon, a silicon-containing compound, AlO ｘ , HfO ｘ , ZrO ｘ 17. The method for producing a substrate according to claim 14, wherein the metal is at least one selected from the group consisting of TiN, TaN, Ti, Co, Ru, Ta and W.

18. The method for manufacturing a substrate according to claim 3 or 4, wherein in the film forming step, the oxygen concentration in the reaction system is 10 ppm by volume or less.

19. A molybdenum precursor having a tungsten concentration of less than 100 ppb by weight.

20. A method for producing a molybdenum precursor having a tungsten concentration of less than 100 ppb by mass, comprising a removal step of removing tungsten from a crude molybdenum precursor having a tungsten concentration of more than 100 ppb by mass using at least one method selected from the group consisting of distillation and adsorption using a solid metal fluoride.

21. The method for producing a molybdenum precursor according to claim 20, wherein the metal fluoride is at least one selected from the group consisting of alkali metal fluorides and alkaline earth metal fluorides.

22. The method for producing a molybdenum precursor according to claim 20 or 21, wherein the temperature of the metal fluoride is 50°C to 200°C.

23. The method for producing a molybdenum precursor according to claim 20 or 21, wherein uranium is also removed in the removal step.

24. The method for producing a molybdenum precursor according to claim 20 or 21, wherein the tungsten concentration in the crude molybdenum precursor is 10 ppm by mass to 0.1% by mass.

25. A method for producing a molybdenum precursor according to claim 20 or 21, wherein the tungsten concentration in the produced molybdenum precursor is 10 ppb by mass or less.

26. A method for producing a molybdenum precursor according to claim 20 or 21, wherein the uranium concentration in the produced molybdenum precursor is 10 ppb by mass or less.

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