Method for forming transition metal dichalcogenide film

Abstract

Disclosed is a method for forming a transition metal dichalcogenide film by chalcogenation of a transition metal-containing film, the method including: (a) a step for providing a substrate which comprises at least one first film that is selected from the group consisting of a silicon-containing film and a metal-containing film; (b) a step for forming a first transition metal-containing film on the first film in a nitrogen-containing gas atmosphere; and (c) a step for annealing the substrate in a first atmosphere that contains a chalcogenation gas after the step (b).

Description

Method for forming transition metal dichalcogenide films

[0001] Exemplary embodiments of this disclosure relate to a method for forming transition metal dichalcogenide films.

[0002] Patent Document 1 discloses a technique for forming a transition metal oxide film on a substrate surface and then converting the transition metal oxide film into a transition metal dichalcogenide.

[0003] Special Publication No. 2024-526208

[0004] This disclosure provides a technique for suppressing oxidation at the film interface when forming a transition metal dichalcogenide film.

[0005] A method for forming a transition metal dichalcogenide film by chalcogenizing a transition metal-containing film in one exemplary embodiment of the present disclosure includes the steps of: (a) providing a substrate including at least one first film selected from the group consisting of silicon-containing films and metal-containing films; (b) forming a first transition metal-containing film on the first film in a nitrogen-containing gas atmosphere; and (c) annealing the substrate in a first atmosphere containing a chalcogenizing gas after (b).

[0006] According to one exemplary embodiment of the present disclosure, a technique can be provided that can suppress oxidation at the film interface when forming a transition metal dichalcogenide film.

[0007] This is a diagram illustrating an example configuration of a substrate processing apparatus. This is a flowchart illustrating an example of a method for forming a transition metal dichalcogenide film. This is a diagram illustrating an example of the cross-sectional structure of a substrate W provided in step ST1. This is a diagram illustrating an example of the cross-sectional structure of a substrate W during step ST2. This is a diagram illustrating an example of the cross-sectional structure of a substrate W after step ST2 has been performed. This is a diagram illustrating an example of the cross-sectional structure of a substrate W during step ST3. This is a diagram illustrating an example of the cross-sectional structure of a substrate W after step ST3 has been performed. This is a flowchart illustrating a modified version of the method for forming a transition metal dichalcogenide film. This is a diagram illustrating an example of the cross-sectional structure of a substrate W during step ST2A. This is a diagram illustrating an example of the cross-sectional structure of a substrate W after step ST2A has been performed and step ST3 has been performed. This is a diagram illustrating an example of the cross-sectional structure of a substrate W after step ST2A has been performed and step ST3 has been performed. This is a flowchart illustrating an example of the cross-sectional structure of a substrate W after step ST2A has been performed and step ST3 has been performed. This is a flowchart illustrating another modified version of the method for forming a transition metal dichalcogenide film. This is a diagram illustrating an example of the cross-sectional structure of a substrate W after step ST3 has been performed and step ST4 has been performed. This figure illustrates an example of the cross-sectional structure of the substrate W after going through process ST3 and then performing process ST4.

[0008] The embodiments of this disclosure are described below.

[0009] In one exemplary embodiment, a method is provided for forming a transition metal dichalcogenide film by chalcogenizing a transition metal-containing film, comprising: (a) providing a substrate containing at least one first film selected from the group consisting of silicon-containing films and metal-containing films; (b) forming a first transition metal-containing film on the first film in a nitrogen-containing gas atmosphere; and (c) annealing the substrate in a first atmosphere containing a chalcogenizing gas after (b).

[0010] In one exemplary embodiment, the first transition metal-containing film is a transition metal nitride film.

[0011] In one exemplary embodiment, the first transition metal-containing film contains at least one selected from the group consisting of molybdenum, tungsten, tantalum, niobium, zirconium, hafnium, titanium, vanadium, chromium, tin, and scandium.

[0012] In one exemplary embodiment, the expansion rate of the first transition metal-containing film before and after performing (c) is less than 150%.

[0013] In one exemplary embodiment, (d) further includes the step of forming a second transition metal-containing film on the first transition metal-containing film in an oxygen atmosphere between (b) and (c).

[0014] In one exemplary embodiment, the second transition metal-containing film is a transition metal oxide film.

[0015] In one exemplary embodiment, the second transition metal-containing film contains at least one selected from the group consisting of molybdenum, tungsten, tantalum, niobium, zirconium, hafnium, titanium, vanadium, chromium, tin, and scandium.

[0016] In one exemplary embodiment, the expansion rate of the second transition metal-containing film before and after performing (c) is less than 150%.

[0017] In one exemplary embodiment, the chalcogenizing gas includes at least one selected from the group consisting of hydrogen sulfide, organosulfur compounds, hydrogen selenide, organoselenide compounds, hydrogen telluride, and organotelluride compounds.

[0018] In one exemplary embodiment, the transition metal dichalcogenide film is a sulfide transition metal film, a selenide transition metal film, or a telluride transition metal film.

[0019] In one exemplary embodiment, (e) the step of annealing the substrate in a second atmosphere that does not contain chalcogenizing gas after (c) is further included.

[0020] In one exemplary embodiment, in (c) above, the substrate is annealed at a first temperature, and in (e) above, the substrate is annealed at a second temperature, wherein the second temperature is higher than the first temperature.

[0021] In one exemplary embodiment, in (c) above, the substrate is annealed at a first pressure, and in (e) above, the substrate is annealed at a second pressure, wherein the second pressure is greater than the first pressure.

[0022] In one exemplary embodiment, the second atmosphere contains a noble gas.

[0023] In one exemplary embodiment, in at least one of (c) and (e) above, the annealing process is performed for a period of 1 minute or more and 480 minutes or less.

[0024] In one exemplary embodiment, (b) and (c) are performed in the same chamber.

[0025] Hereinafter, each embodiment of this disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are denoted by the same reference numeral, and redundant explanations are omitted. Unless otherwise specified, positional relationships such as top, bottom, left, and right will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and actual ratios are not limited to those shown.

[0026] <Example of a substrate processing apparatus> Figure 1 is a diagram illustrating an example of the configuration of a substrate processing apparatus 1. In one embodiment, the substrate processing apparatus 1 includes a chamber 10, a substrate support section 11, a gas introduction section 13, an exhaust section 14, a gas supply section 15, a power supply 16, and a control section 2.

[0027] The chamber 10 is configured to form a processing space 10s inside. The substrate support 11 is located inside the chamber 10. The substrate support 11 is located at the bottom of the processing space 10s.

[0028] In one embodiment, the substrate support portion 11 has a disc shape with thickness in the vertical direction (up and down direction). The substrate support portion 11 is equipped with a heat source 30 inside. The heat source 30 is, for example, a heater and is configured to generate heat when power is supplied from the power supply 16.

[0029] In one embodiment, the gas introduction section 13 is located above the substrate support section 11. The gas introduction section 13 includes at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlet ports 13c. Gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the processing space 10s through the plurality of gas inlet ports 13c. The plurality of gas inlet ports 13c are connected to the gas supply section 15.

[0030] The gas supply unit 15 comprises at least one gas source 50 and at least one flow controller 51. In one embodiment, the gas supply unit 15 is configured to supply at least one processing gas to the gas introduction unit 13 from the corresponding gas source 50 via the corresponding flow controller 51. Each flow controller 51 includes, for example, a mass flow controller or a pressure-controlled flow controller. The processing gas is appropriately selected depending on the process to be performed. In one embodiment, the processing gas may be at least one selected from the group consisting of nitrogen gas, oxygen gas, chalcogenized gas and noble gas.

[0031] The exhaust section 14 is connected to a gas outlet 10e, for example, located at the bottom of the chamber 10. The exhaust section 14 includes a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the pressure in the processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0032] The control unit 2 processes computer-executable instructions that cause the substrate processing apparatus 1 to perform the various processes described herein. The control unit 2 may be configured to control each element of the substrate processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the substrate processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is implemented, for example, by a computer 2a. The processing unit 2a1 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or it may be obtained via a medium when needed. The obtained program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the substrate processing device 1 via a communication line such as a LAN (Local Area Network).

[0033] <Example of a method for forming a transition metal dichalcogenide film> Figure 2 is a flowchart of an example of a method for forming a transition metal dichalcogenide film (hereinafter also referred to as "this method") according to one exemplary embodiment. As shown in Figure 2, in one embodiment, this method includes a step ST1 of providing a substrate W, a step ST2 of forming a transition metal-containing film in a nitrogen-containing gas atmosphere, and a step ST3 of annealing the substrate W in a first atmosphere (hereinafter also referred to as "first annealing treatment"). This method may be performed as a method for manufacturing a substrate W containing a transition metal dichalcogenide film. In one embodiment, this method may be performed using a substrate processing apparatus 1 shown in Figure 1. Below, the case in which a control unit 2 controls each part of the substrate processing apparatus 1 to perform this method on the substrate W will be described as an example.

[0034] (Step ST1: Provision of Substrate) In one embodiment, in step ST1, as shown in Figure 1, the substrate W is provided into the chamber 10 of the substrate processing apparatus 1. The substrate W is placed on the substrate support 11. The substrate W may be used in the manufacture of semiconductor devices. Semiconductor devices include, for example, memory devices such as DRAM and 3D-NAND flash memory, and logic devices. The size of the substrate W may be adjusted according to the application, and for example, it may have a diameter of 150 mm or more or 300 mm or more.

[0035] Figure 3 is a diagram illustrating an example of the configuration of the substrate W in step ST1. The substrate W includes at least one first film F1 selected from the group consisting of silicon-containing films and metal-containing films. Examples of silicon-containing films include spin-on-glass (SOG) films, Si-containing anti-reflective films (SiARC), silicon oxide films, silicon nitride films, silicon oxynitride films, silicon carbide films, silicon carbonitride films, polycrystalline silicon films, and amorphous silicon films. In one embodiment, the silicon-containing film may be a part (surface layer) of a single-crystal silicon wafer. In this case, by performing this method, a transition metal dichalcogenide film can be directly formed on a part (surface layer) of a single-crystal silicon wafer. Examples of metal-containing films include tungsten, hafnium, zirconium, tin, and titanium.

[0036] In one embodiment, the substrate W may further have another film under the first film F1. In the example of FIG. 3, the first film F1 is formed on an arbitrary underlying film UF. The underlying film UF may be a silicon wafer, or may be an organic film, a dielectric film, a metal film, a semiconductor film, etc. formed on the silicon wafer. The first film F1 and the underlying film UF may each be composed of a plurality of films laminated. The underlying film UF may be a silicon oxide film. In one embodiment, the substrate W may further have another film under the underlying film UF.

[0037] The first film F1 and the underlying film UF are each formed by an arbitrary method. In one embodiment, the first film F1 and the underlying film UF may each be formed by a CVD (Chemical Vapor Deposition) method, an ALD (Atomic Layer Deposition) method, an MLD (Molecular Layer Deposition) method, a PVD (Physical Vapor Deposition) method, a spin coating method, or the like. The first film F1 and the underlying film UF may each be a flat film, or may be a film having irregularities.

[0038] At least a part of the process of forming the first film F1 and the underlying film UF on the substrate W may be performed in the chamber 10 as a part of the step ST1. For example, the first film F1 is formed in the step ST1. In this case, the substrate processing apparatus 1 has a function of forming the first film F1. In one embodiment, after all or part of the first film F1 and the underlying film UF on the substrate W are formed by a device or chamber outside the substrate processing apparatus 1, the substrate W is provided in the chamber 10.

[0039] In one embodiment, after the substrate W is provided to the substrate support 11, the temperature of the substrate support 11 or the substrate W is controlled to a given temperature by the heat source 30. Controlling the temperature of the substrate support 11 or the substrate W to a given temperature may include setting the temperature of the heat source 30 to a given temperature or to a temperature different from the given temperature. The given temperature may be within the range of 0°C to 1100°C. The timing at which the temperature of the substrate support 11 or the substrate W begins to be controlled to a given temperature may be before, after, or simultaneously with the placement of the substrate W on the substrate support 11. The temperature of the substrate support 11 or the substrate W may be changed during the execution of step ST1, or it may be changed in any of steps ST2, ST2A, ST3, and ST4 described later.

[0040] (Step ST2: Formation of transition metal-containing film) In step ST2, a first transition metal-containing film MF1 is formed on the first film F1 in a nitrogen-containing gas atmosphere. In one embodiment, the first transition metal-containing film MF1 is a film containing at least one of a film composed of an elemental transition metal or a film composed of a compound of a transition metal. The first transition metal-containing film MF1 may contain, but is not limited to, any of the following or a combination thereof as the transition metal: molybdenum, tungsten, tantalum, niobium, zirconium, hafnium, titanium, vanadium, chromium, tin, scandium, etc. The first transition metal-containing film MF1 may also be a transition metal nitride film.

[0041] Figure 4 is a diagram illustrating an example of the cross-sectional structure of the substrate W during process ST2. Process ST2 is performed with the substrate W containing the first film F1 placed in a nitrogen-containing gas atmosphere NA. The nitrogen-containing gas atmosphere NA is composed of nitrogen (N ２ ) may contain gas, ammonia (NH ３ ) may contain gas. In one embodiment, the chamber 10 may first be filled with an ammonia gas atmosphere, and then nitrogen gas may be introduced therein. Nitrogen (N) in a nitrogen-containing gas atmosphere NA ２ The gas concentration may be 99% by volume or more, and may be 100% by volume or more. Ammonia (NH) in a nitrogen-containing gas atmosphere NA ３The gas concentration may be 99% by volume or more, and may be 100% by volume or more. Also, the oxygen concentration in the nitrogen-containing gas atmosphere NA may be less than 1% by volume, and may be 0% by volume. As shown in FIG. 4, the step ST2 may be executed in a state where the substrate W is disposed in the chamber 10 such that the nitrogen-containing gas atmosphere NA acts on the vicinity F1s of the surface of the first film F1. The method for forming the first transition metal-containing film MF1 on the first film F1 is not particularly limited, and examples thereof include an ALD method, a PVD method, a CVD method, and the like. The first transition metal-containing film MF1 may be a flat film or may be a film having irregularities.

[0042] FIG. 5 is a diagram for explaining an example of a cross-sectional structure of the substrate W after the step ST2 is executed. In the example of FIG. 5, by executing the step ST2, a substrate W including an underlayer film UF, a first film F1, and a first transition metal-containing film MF1 can be obtained. The first transition metal-containing film MF1 may be a transition metal nitride film. As described above, since the step ST2 is executed in the nitrogen-containing gas atmosphere NA, the influence of oxidation in the vicinity F1s of the surface of the first film F1 is suppressed as compared with, for example, the case where a transition metal-containing film is formed in an oxygen atmosphere. As an example, when the first film F1 is a titanium-containing film, such oxidation is suppressed, and as a result, electrical conductivity can be ensured. Also, as an example, when the first film F1 is a silicon nitride film, such oxidation is suppressed, and as a result, an increase in the number of steps in subsequent etching can be prevented.

[0043] (Step ST3: First annealing treatment) In the step ST3, the substrate W is annealed (first annealing treatment) in a first atmosphere containing a chalcogenide gas.

[0044] During the execution of the step ST3, the temperature of the substrate W is adjusted to a first temperature. After the substrate W is provided on the substrate support portion 11 shown in FIG. 1 or before the substrate W is provided on the substrate support portion 11, the temperature of the substrate W or the substrate support portion 11 may be adjusted to the first temperature by the heat source 30. The first temperature may be in the range of room temperature or higher and 700°C or lower. The first temperature may be in the range of 20°C or higher and 700°C or lower. The first temperature may be in the range of 100°C or higher and 500°C or lower.

[0045] During the execution of process ST3, the pressure inside the chamber 10 is adjusted to a first pressure. The first pressure may be in the range of 1 kPa or more and 200 kPa or less. In one embodiment, the first pressure is adjusted by exhausting the atmosphere inside the chamber 10 with the exhaust unit 14.

[0046] The first annealing process may be performed for a period of 10 minutes or more and 480 minutes or less. The first annealing process may be performed for 480 minutes or more.

[0047] Figure 6 is a diagram illustrating an example of the cross-sectional structure of the substrate W during process ST3. As shown in Figure 6, the chamber 10 is adjusted to a first atmosphere A1. The first atmosphere A1 is an atmosphere containing a chalcogenizing gas. When chalcogenization is performed with sulfur, the chalcogenizing gas can be, for example, hydrogen sulfide or an organic sulfur compound, but when chalcogenization is performed with selenium or tellurium, a gas containing those elements is used. In one embodiment, the first atmosphere A1 is adjusted by supplying a processing gas into the chamber 10 from the gas introduction section 13. Process ST3 yields a transition metal dichalcogenide film corresponding to the chalcogenizing gas. In one embodiment, the chalcogenizing gas includes at least one selected from the group consisting of hydrogen sulfide, an organic sulfur compound, hydrogen selenide, an organic selenide compound, hydrogen telluride, and an organic tellurium compound. In one embodiment, the transition metal dichalcogenide film is a sulfurized transition metal film, a selenized transition metal film, or a tellurized transition metal film.

[0048] Figure 7 is a diagram illustrating an example of the cross-sectional structure of the substrate W after step ST3 is performed. In step ST3, the first transition metal-containing film MF1 on the substrate W is heated in a first atmosphere A1 containing a chalcogenizing gas (e.g., hydrogen sulfide gas), thereby chalcogenizing the first transition metal-containing film MF1. As a result, a first transition metal dichalcogenide film TD1 is formed on the first film F1 on the substrate W. According to this method, by performing at least steps ST1, ST2, and ST3, a transition metal dichalcogenide film can be formed while suppressing the effect of oxidation in the vicinity F1s of the surface of the first film F1.

[0049] In one embodiment, the expansion rate of the first transition metal-containing film MF1 before and after step ST3 may be less than 150% and may be 125% or less. The expansion rate can be calculated as 100 × V1b / V1a from the volume V1a of the first transition metal-containing film MF1 after step ST2 and the volume V1b of the first transition metal dichalcogenide film TD1 after step ST3. A smaller expansion rate tends to reduce the strain within the film that may occur due to chalcogenization. As a result, delamination between the films constituting the substrate W tends to be suppressed. The expansion rate can be adjusted to the above range, for example, based on the density difference between the first transition metal-containing film MF1 and the first transition metal dichalcogenide film TD1. For example, if the first transition metal-containing film MF1 is a transition metal nitride film (a film containing transition metal nitrides), the density difference between it and the first transition metal dichalcogenide film TD1 obtained by sulfidating it tends to be small.

[0050] After the completion of process ST3, the substrate W is removed from the chamber 10 to the outside.

[0051] <Modification 1> Figure 8 is a flowchart showing a modified method for forming a transition metal dichalcogenide film. As shown in Figure 8, the etching method of this modified method includes a step ST1 for providing a substrate W, a step ST2 for forming a transition metal-containing film in a nitrogen-containing gas atmosphere, a step ST2A for further forming a transition metal-containing film in an oxygen atmosphere, and a step ST3 for annealing the substrate W in a first atmosphere. Steps ST1, ST2, and ST3 in this modified method may be performed in the same manner as steps ST1, ST2, and ST3 described above for the present method. Step ST2A is performed between steps ST2 and ST3.

[0052] In step ST2A, a second transition metal-containing film MF2 is formed on the first transition metal-containing film MF1 in an oxygen atmosphere. In one embodiment, the second transition metal-containing film MF2 is a film containing at least one of a film composed of an elemental transition metal or a film composed of a compound of a transition metal. The second transition metal-containing film MF2 may, but is not limited to, contain any or a combination thereof of molybdenum, tungsten, tantalum, niobium, zirconium, hafnium, titanium, vanadium, chromium, tin, scandium, etc. as the transition metal. The second transition metal-containing film MF2 may also be a transition metal oxide film. The transition metal species in the second transition metal-containing film MF2 may be the same or different. The method for forming the second transition metal-containing film MF2 on the first transition metal-containing film MF1 is not particularly limited, but examples include CVD, ALD, MLD, PVD, and spin coating. The second transition metal-containing film MF2 may be a flat film or a film with irregularities.

[0053] Figure 9 is a diagram illustrating an example of the cross-sectional structure of a substrate W during process ST2A. As shown in Figure 9, process ST2A is performed with the substrate W, which includes the first film F1 and the first transition metal-containing film MF1, placed in an oxygen atmosphere OA. The oxygen concentration in the oxygen atmosphere OA may be 99% by volume or more, and may be 100% by volume. The nitrogen concentration in the oxygen atmosphere OA may be 1% by volume or less, and may be 0% by volume. The substrate W in Figure 9 has undergone process ST2, and as described above, performing process ST2 tends to suppress oxidation of the surface vicinity F1s of the first film F1. Furthermore, the first transition metal-containing film MF1 formed on the first film F1 by process ST2 can function as a barrier layer against the oxidizing atmosphere OA. Therefore, even when process ST2A is performed in an oxygen atmosphere OA, oxidation of the surface vicinity F1s of the first film F1 tends to be suppressed.

[0054] Figure 10 is a diagram illustrating an example of the cross-sectional structure of the substrate W after performing step ST2A. In the example of Figure 10, by performing step ST2A, a substrate W can be obtained that includes a first film F1, a first transition metal-containing film MF1, and a second transition metal-containing film MF2. The first transition metal-containing film MF1 may be a transition metal nitride film. The second transition metal-containing film MF2 may be a transition metal oxide film.

[0055] Figure 11 is a diagram illustrating an example of the cross-sectional structure of the substrate W after performing step ST2A and during step ST3. As shown in Figure 11, the chamber 10 is adjusted to a first atmosphere A1. The first atmosphere A1 is an atmosphere containing chalcogenizing gas, which can act on both the first transition metal-containing film MF1 and the second transition metal-containing film MF2.

[0056] Figure 12 is a diagram illustrating an example of the cross-sectional structure of the substrate W after performing step ST3 via step ST2A. As described above, the chalcogenizing gas in the first atmosphere A1 acts on both the first transition metal-containing film MF1 and the second transition metal-containing film MF2, causing both to be chalcogenized as shown in Figure 12. As a result, the first transition metal dichalcogenide film TD1 and the second transition metal dichalcogenide film TD2 are formed on the first film F1 on the substrate W. According to this method, by performing at least steps ST1, ST2, ST2A, and ST3, it is possible to form multiple types of transition metal dichalcogenide films while suppressing the effect of oxidation in the vicinity F1s of the surface of the first film F1.

[0057] In one embodiment, the expansion rate of the second transition metal-containing film MF2 before and after step ST3 may be less than 150% and may be 125% or less. The expansion rate can be calculated as 100 × V2b / V2a from the volume V2a of the second transition metal-containing film MF2 after step ST2A and the volume V2b of the second transition metal dichalcogenide film TD2 after step ST3. A smaller expansion rate tends to reduce the strain within the film that may occur due to chalcogenization. As a result, delamination between the films constituting the substrate W tends to be suppressed. The expansion rate can be adjusted to the above range, for example, based on the density difference between the second transition metal-containing film MF2 and the second transition metal dichalcogenide film TD2. For example, if the second transition metal-containing film MF2 is a transition metal oxide film (a film containing a transition metal oxide), the density difference between it and the second transition metal dichalcogenide film TD2 obtained by sulfidating it tends to be small.

[0058] <Modification 2> Figure 13 is a flowchart showing another modification of the method for forming a transition metal dichalcogenide film. As shown in Figure 13, the etching method of this modification includes a step ST1 for providing a substrate W, a step ST2 for forming a transition metal-containing film in a nitrogen-containing gas atmosphere, a step ST3 for annealing the substrate W in a first atmosphere, and a step ST4 for annealing the substrate W in a second atmosphere A2 (second annealing). Steps ST1, ST2, and ST3 in this modification may be performed in the same manner as steps ST1, ST2, and ST3 described above for the present method. Alternatively, step ST2A described in Modification 1 may be performed between steps ST2 and ST3.

[0059] In step ST4, the substrate W is annealed (second annealing treatment) in a second atmosphere A2 that does not contain chalcogenizing gas.

[0060] During process ST4, the temperature of the substrate W is adjusted to a second temperature. After process ST3, the temperature of the substrate W or the substrate support 11 shown in Figure 1 is adjusted to a second temperature by the heat source 30. The second temperature may be higher than the first temperature. The second temperature may be in the range of 900°C to 1100°C.

[0061] During the execution of process ST4, the pressure inside the chamber 10 is adjusted to a second pressure. The second pressure may be in the range of 0 kPa or more and 200 kPa or less. The second pressure may be a vacuum pressure. The second pressure may be 200 kPa or more. The second pressure may be greater than the first pressure. In one embodiment, the second pressure is adjusted by exhausting the atmosphere inside the chamber 10 by the exhaust unit 14.

[0062] The second annealing process may be performed for a period of 10 minutes or more and 480 minutes or less. The first annealing process may be performed for 480 minutes or more.

[0063] The chamber 10 is adjusted to a second atmosphere A2. The second atmosphere A2 is an atmosphere that is substantially free of chalcogenizing gas. In one embodiment, the second atmosphere A2 is adjusted by exhausting the chalcogenizing gas from the chamber 10 using the exhaust unit 14 and supplying a processing gas into the chamber 10 from the gas introduction unit 13. A noble gas may be used as the processing gas. The noble gas may be argon gas.

[0064] Figure 14 is a diagram illustrating an example of the cross-sectional structure of the substrate W after step ST3 has been performed and during step ST4. Figure 15 is a diagram illustrating an example of the cross-sectional structure of the substrate W after step ST4 has been performed via step ST3. As shown in Figure 14, during step ST4, the first transition metal dichalcogenide film TD1 may be subjected to the action of the second atmosphere A2. When the substrate W is heated in this state, crystallization of the first transition metal dichalcogenide film TD1 progresses. After step ST4 is performed, as shown in Figure 15, the second transition metal dichalcogenide film TD1a is formed on the first film F1. The second transition metal dichalcogenide film TD1a may be a film with higher crystallinity than the first transition metal dichalcogenide film TD1. The first transition metal dichalcogenide film TD1 and the second transition metal dichalcogenide film TD1a may each be thin films of a single atomic layer or multiple atomic layers. The first transition metal dichalcogenide film TD1 and the second transition metal dichalcogenide film TD1a may each be thin films of 10 nm or less. The first transition metal dichalcogenide film TD1 and the second transition metal dichalcogenide film TD1a may each be two-dimensional materials.

[0065] Steps ST3 and ST4 may be carried out in the same chamber. In this case, after step ST3, the substrate W is not exposed to the atmosphere, and step ST4 can be carried out immediately afterward. This tends to result in the formation of a transition metal dichalcogenide film with higher crystallinity.

[0066] <Examples> Next, examples will be described. This disclosure is not limited in any way by the following examples.

[0067] (Reference Example 1) An apparatus having the same configuration as the substrate processing apparatus 1 shown in Figure 1 was prepared. Inside the chamber 10 of the apparatus, a substrate having a silicon-containing film on a silicon wafer was placed on the substrate support part 11. The base vacuum inside the chamber 10 was set to 10 －３ In the first half of Pa, within a vacuum atmosphere, WO ３ A transition metal-containing film was deposited on a silicon-containing film using electron beam deposition with the following raw materials: tungsten oxide (WO ３A film was formed. Next, a first annealing treatment was performed for 10 minutes while supplying hydrogen sulfide gas at 800 °C and 50 kPa to chalcogenize the tungsten oxide-containing film, thereby forming a tungsten sulfide-containing film on the silicon-containing film. As a result of observing the obtained substrate, no peeling was observed between the films constituting the substrate. Based on the thicknesses of the tungsten oxide-containing film and the tungsten sulfide-containing film, the volume was determined, and as a result of calculating the expansion ratio, it was 110%. The expansion ratio was calculated as 100 × V1b / V1a from the volume V1a of the tungsten oxide-containing film during formation and the volume V1b of the tungsten sulfide-containing film (the expansion ratio was calculated in the same manner in the following examples). On the other hand, as a result of analyzing the vicinity of the surface of the silicon-containing film on the side of the tungsten sulfide-containing film, it was found that an oxide film was formed.

[0068] (Reference Example 2) The following treatment was performed on the substrate in the chamber 10 prepared in the same manner as in Reference Example 1. That is, the inside of the chamber 10 was set to a vacuum atmosphere with a base vacuum of the first half of 10 －３ Pa, and then oxygen was introduced to set the inside of the chamber 10 to an oxygen atmosphere of the first half of 10 －2 Pa. In this oxygen atmosphere, a transition metal-containing film was formed on the silicon-containing film by an electron beam evaporation method using Mo metal as a raw material. As a result, a molybdenum oxide-containing film was formed on the silicon-containing film. Next, a first annealing treatment was performed in the same manner as in Reference Example 1, and by chalcogenizing molybdenum oxide, a molybdenum sulfide-containing film was formed on the silicon-containing film. As a result of observing the obtained substrate, no peeling was observed between the films constituting the substrate. Based on the thicknesses of the molybdenum oxide-containing film and the molybdenum sulfide-containing film, the volume was determined, and as a result of calculating the expansion ratio, it was 108%. On the other hand, as a result of analyzing the vicinity of the surface of the silicon-containing film on the side of the molybdenum sulfide-containing film, it was found that an oxide film was formed.

[0069] (Reference Example 3) The following process was performed on a substrate in chamber 10, which was prepared in the same manner as in Reference Example 1. Specifically, the chamber 10 was subjected to a vacuum atmosphere similar to that in Reference Example 1. Ar was introduced into this vacuum atmosphere, and sputter deposition was performed on the silicon-containing film using W metal as the target. As a result, a tungsten-containing film was formed on the silicon-containing film. Next, a first annealing treatment was performed in the same manner as in Reference Example 1, and a tungsten sulfide-containing film was formed on the silicon-containing film by chalcogenizing β-tungsten. Observation of the obtained substrate revealed delamination between the films constituting the substrate. The volume was determined based on the thickness of the β-tungsten-containing film and the tungsten sulfide-containing film, and the expansion rate was calculated to be 190%. On the other hand, analysis of the vicinity of the surface of the silicon-containing film on the tungsten sulfide-containing film side revealed that no oxide film had been formed.

[0070] (Reference Example 4) The following process was performed on a substrate in a chamber 10, which was prepared in the same manner as in Reference Example 1. Specifically, the chamber 10 was made into a vacuum atmosphere similar to that in Reference Example 1. Ar was introduced into this vacuum atmosphere, and sputter deposition was performed on the silicon-containing film using Mo metal as the target. As a result, a molybdenum-containing film was formed on the silicon-containing film. Next, a first annealing treatment was performed in the same manner as in Reference Example 1, and a molybdenum sulfide-containing film was formed on the silicon-containing film by chalcogenizing the molybdenum. Observation of the obtained substrate revealed delamination between the films constituting the substrate. The volume was determined based on the thickness of the molybdenum-containing film and the molybdenum sulfide-containing film, and the expansion rate was calculated to be 184%. On the other hand, analysis of the vicinity of the surface of the silicon-containing film on the molybdenum sulfide-containing film side revealed that no oxide film had been formed.

[0071] (Reference Example 5) The following process was performed on a substrate in chamber 10, which was prepared in the same manner as in Reference Example 1. Specifically, the chamber 10 was subjected to a vacuum atmosphere similar to that in Reference Example 1. In this vacuum atmosphere, a transition metal-containing film was deposited on a silicon-containing film by electron beam deposition using W metal as the raw material. As a result, a tungsten-containing film was formed on the silicon-containing film. A first annealing treatment was performed in the same manner as in Reference Example 1, and a tungsten sulfide-containing film was formed on the silicon-containing film by chalcogenization of the tungsten. Observation of the obtained substrate revealed delamination between the films constituting the substrate. The volume was determined based on the thickness of the tungsten-containing film and the tungsten sulfide-containing film, and the expansion rate was calculated to be 172%. On the other hand, analysis of the vicinity of the surface of the silicon-containing film on the tungsten sulfide-containing film side revealed that no oxide film had been formed.

[0072] (Example 1) The following process was performed on a substrate in a chamber 10, which was prepared in the same manner as in Reference Example 1. Specifically, the chamber 10 was set to a nitrogen gas atmosphere. In this nitrogen gas atmosphere, sputter deposition was performed on a silicon-containing film using a W metal as the target. The nitrogen gas concentration in the atmosphere was 99% by volume or higher. As a result, a tungsten nitride-containing film was formed on the silicon-containing film. Next, a first annealing treatment was performed in the same manner as in Reference Example 1, and a tungsten sulfide-containing film was formed on the silicon-containing film by chalcogenizing the tungsten nitride. Observation of the obtained substrate revealed no delamination between the films constituting the substrate. The volume was determined based on the thickness of the tungsten nitride-containing film and the tungsten sulfide-containing film, and the expansion rate was calculated to be 120%. On the other hand, analysis of the vicinity of the surface of the silicon-containing film on the tungsten sulfide-containing film side revealed that no oxide film had been formed.

[0073] A comparison of Reference Examples 1 and 2 with Example 1 reveals the following: In Reference Examples 1 and 2, where transition metal-containing films were formed in an oxygen atmosphere, oxidation was observed near the surface of the silicon-containing film on the tungsten sulfide-containing film side. On the other hand, in Example 1, where transition metal-containing films were formed in a nitrogen-containing gas atmosphere, no oxidation was observed near the surface of the silicon-containing film on the tungsten sulfide-containing film side. Thus, this method can suppress oxidation at the film interface when forming transition metal dichalcogenide films.

[0074] A comparison of Reference Examples 3-5 and Example 1 reveals the following: In Reference Examples 3-5, where transition metal-containing films were formed in a vacuum atmosphere, the expansion rate exceeded 150%, and delamination between the films constituting the substrate was observed. On the other hand, in Example 1, where transition metal-containing films were formed in a nitrogen-containing gas atmosphere, the expansion rate was small, and no delamination between the films constituting the substrate was observed. Thus, this method can suppress delamination between films when forming transition metal dichalcogenide films.

[0075] From the results of Reference Examples 1 and 2, it can be seen that forming transition metal dichalcogenides from transition metal oxides can be advantageous in terms of expansion coefficient. For example, in Example 1, the procedure after forming the tungsten nitride-containing film on the silicon-containing film can be modified as follows. In Example 1, a tungsten oxide-containing film can also be formed on the tungsten nitride-containing film, in the same manner as in Reference Example 1. In this case, two transition metal-containing films with low expansion coefficients can be formed on the silicon-containing film. Then, by performing chalcogenization according to the procedure of Example 1, a transition metal dichalcogenide film can be formed while suppressing both oxidation at the film interface and delamination between films.

[0076] (Example 2) The following process was performed on the substrate in the chamber 10, which was prepared in the same manner as in Reference Example 1. That is, the inside of the chamber 10 was made into an ammonia gas atmosphere. In this ammonia gas atmosphere, MoO was used as a precursor. ２ Cl ２The material was supplied to the chamber 10 using nitrogen gas as a carrier gas, and a transition metal-containing film was deposited on the silicon-containing film by the ALD method. Ammonia (NH₄) in the atmosphere ３ The gas concentration was 99% by volume or higher. As a result, a molybdenum nitride-containing film was formed on the silicon-containing film. Next, a first annealing treatment was performed for 10 minutes at 200°C and 50 kPa while supplying hydrogen sulfide, and a molybdenum sulfide-containing film was formed on the silicon-containing film by chalcogenizing the molybdenum nitride. Furthermore, a second annealing treatment was performed for 10 minutes at 1100°C and 100 kPa while supplying argon gas. Observation of the obtained substrate revealed no delamination between the films constituting the substrate. The volume was determined based on the thickness of the molybdenum nitride-containing film and the molybdenum sulfide-containing film, and the expansion rate was calculated to be 108%. On the other hand, analysis of the vicinity of the surface of the silicon-containing film on the molybdenum sulfide-containing film side revealed that no oxide film had been formed.

[0077] Embodiments of this disclosure further include the following embodiments:

[0078] (Note 1) A method for forming a transition metal dichalcogenide film by chalcogenizing a transition metal-containing film, comprising: (a) providing a substrate containing at least one first film selected from the group consisting of silicon-containing films and metal-containing films; (b) forming a first transition metal-containing film on the first film in a nitrogen-containing gas atmosphere; and (c) annealing the substrate in a first atmosphere containing a chalcogenizing gas after (b).

[0079] (Note 2) The method according to Note 1, wherein the first transition metal-containing film is a transition metal nitride film.

[0080] (Note 3) The method according to Note 1 or 2, wherein the first transition metal-containing film contains at least one selected from the group consisting of molybdenum, tungsten, tantalum, niobium, zirconium, hafnium, titanium, vanadium, chromium, tin, and scandium.

[0081] (Note 4) The method according to any one of Notes 1 to 3, wherein the expansion rate of the first transition metal-containing film before and after performing (c) is less than 150%.

[0082] (Note 5) (d) The method according to any one of Notes 1 to 4, further comprising the step of forming a second transition metal-containing film on the first transition metal-containing film in an oxygen atmosphere between (b) and (c).

[0083] (Note 6) The method according to Note 5, wherein the second transition metal-containing film is a transition metal oxide film.

[0084] (Note 7) The method according to Note 5 or 6, wherein the second transition metal-containing film contains at least one selected from the group consisting of molybdenum, tungsten, tantalum, niobium, zirconium, hafnium, titanium, vanadium, chromium, tin, and scandium.

[0085] (Note 8) The method according to any one of Notes 5 to 7, wherein the expansion rate of the second transition metal-containing film before and after performing (c) is less than 150%.

[0086] (Note 9) The method according to any one of Notes 1 to 8, wherein the chalcogenizing gas comprises at least one selected from the group consisting of hydrogen sulfide, organosulfur compounds, hydrogen selenide, organoselen compounds, hydrogen telluride, and organoteluric compounds.

[0087] (Note 10) The method according to any one of Notes 1 to 9, wherein the transition metal dichalcogenide film is a sulfide transition metal film, a selenide transition metal film, or a telluride transition metal film.

[0088] (Note 11) (e) The method according to any one of Notes 1 to 10, further comprising the step of annealing the substrate in a second atmosphere that does not contain chalcogenizing gas after (c).

[0089] (Note 12) The method according to Note 11, wherein in (c), the substrate is annealed at a first temperature, and in (e), the substrate is annealed at a second temperature, the second temperature being higher than the first temperature.

[0090] (Note 13) The method according to Note 11 or 12, wherein in (c) above, the substrate is annealed with a first pressure, and in (e) above, the substrate is annealed with a second pressure, the second pressure being higher than the first pressure.

[0091] (Note 14) The method according to any one of Notes 11 to 13, wherein the second atmosphere contains a noble gas.

[0092] (Note 15) The method according to any one of Notes 11 to 14, wherein in at least one of (c) and (e), an annealing treatment is performed for a period of 1 minute or more and 480 minutes or less.

[0093] (Note 16) The method described in any of Notes 11 to 15, wherein (b) and (c) are performed in the same chamber.

[0094] The embodiments described above are for illustrative purposes only and are not intended to limit the scope of this disclosure. The embodiments described above can be modified in various ways without departing from the scope and spirit of this disclosure. For example, some components of one embodiment can be added to other embodiments, or some components of one embodiment can be replaced with corresponding components of other embodiments.

[0095] 10... Chamber, W... Substrate, F1... First film, MF1... First transition metal-containing film, MF2... Second transition metal-containing film, TD1... First transition metal dichalcogenide film, TD1a... First transition metal dichalcogenide film after second annealing treatment, TD2... Second transition metal dichalcogenide film, NA... Nitrogen-containing gas atmosphere, OA... Oxygen atmosphere, A1... First atmosphere, A2... Second atmosphere

Claims

1. A method for forming a transition metal dichalcogenide film by chalcogenizing a transition metal-containing film, comprising: (a) providing a substrate containing at least one first film selected from the group consisting of silicon-containing films and metal-containing films; (b) forming a first transition metal-containing film on the first film in a nitrogen-containing gas atmosphere; and (c) annealing the substrate in a first atmosphere containing a chalcogenizing gas after (b).

2. The method according to claim 1, wherein the first transition metal-containing film is a transition metal nitride film.

3. The method according to claim 1, wherein the first transition metal-containing film contains at least one selected from the group consisting of molybdenum, tungsten, tantalum, niobium, zirconium, hafnium, titanium, vanadium, chromium, tin, and scandium.

4. The method according to claim 1, wherein the expansion rate of the first transition metal-containing film before and after performing (c) is less than 150%.

5. (d) The method according to claim 1, further comprising the step of forming a second transition metal-containing film on the first transition metal-containing film in an oxygen atmosphere between (b) and (c).

6. The method according to claim 5, wherein the second transition metal-containing film is a transition metal oxide film.

7. The method according to claim 5, wherein the second transition metal-containing film contains at least one selected from the group consisting of molybdenum, tungsten, tantalum, niobium, zirconium, hafnium, titanium, vanadium, chromium, tin, and scandium.

8. The method according to claim 5, wherein the expansion rate of the second transition metal-containing film before and after performing (c) is less than 150%.

9. The method according to any one of claims 1 to 8, wherein the chalcogenizing gas comprises at least one selected from the group consisting of hydrogen sulfide, organosulfur compounds, hydrogen selenide, organoselen compounds, hydrogen telluride, and organoteluric compounds.

10. The method according to any one of claims 1 to 8, wherein the transition metal dichalcogenide film is a sulfide transition metal film, a selenide transition metal film, or a telluride transition metal film.

11. (e) The method according to claim 1, further comprising the step of annealing the substrate in a second atmosphere that does not contain chalcogenizing gas after (c).

12. The method according to claim 11, wherein in (c), the substrate is annealed at a first temperature, and in (e), the substrate is annealed at a second temperature, the second temperature being higher than the first temperature.

13. The method according to claim 11, wherein, in (c), the substrate is annealed at a first pressure, and in (e), the substrate is annealed at a second pressure, the second pressure being higher than the first pressure.

14. The method according to claim 11, wherein the second atmosphere contains a noble gas.

15. The method according to claim 11, wherein in at least one of (c) and (e), an annealing treatment is performed for a period of 1 minute or more and 480 minutes or less.

16. The method according to claim 11, wherein (b) and (c) are performed in the same chamber.

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