Substrate processing method and substrate processing apparatus

Abstract

A substrate processing method and a substrate processing apparatus are provided. A technology capable of efficiently performing atomic layer etching on a metal film containing ruthenium is provided. A substrate processing method of one embodiment of the present disclosure includes a process of processing a surface of a metal film containing ruthenium with a first treatment liquid to form a metal chloride on the surface of the metal film, and a process of removing the metal chloride with a second treatment liquid.

Description

Technical Field

[0001] The disclosed embodiments relate to a substrate processing method and a substrate processing apparatus. Background Technology

[0002] In recent years, the requirements for miniaturization in semiconductor device manufacturing processes have become increasingly stringent. To meet these requirements, the development of atomic layer etching (ALE) technology, which etches the target material at the atomic layer level, has been continuously advancing. For example, a technique for atomic layer etching of metal films containing cobalt or copper using a wet process has been disclosed (see Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-181984 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This disclosure provides a technique for efficiently etching atomic layers of metal films containing ruthenium.

[0008] Solution for solving the problem

[0009] One aspect of the substrate processing method disclosed herein includes the following steps: treating the surface of a ruthenium-containing metal film with a first processing solution to form a metal chloride on the surface of the metal film; and removing the metal chloride with a second processing solution.

[0010] Invention Effects

[0011] According to this disclosure, atomic layer etching of ruthenium-containing metal films can be performed efficiently. Furthermore, the effects described herein are not necessarily limiting and can be any of the effects described in this disclosure. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing the general structure of the substrate processing system involved in the embodiment.

[0013] Figure 2 This is a schematic diagram illustrating an example of the specific structure of the processing unit involved in the embodiment.

[0014] Figure 3 This is a flowchart illustrating an example of the substrate processing procedure involved in the embodiment.

[0015] Figure 4This is an enlarged cross-sectional view showing an example of the state of the prepared wafer surface according to the embodiment.

[0016] Figure 5 This is an enlarged cross-sectional view showing an example of the state of the wafer surface after the chloride formation treatment involved in the embodiment.

[0017] Figure 6 This is an enlarged cross-sectional view showing an example of the state of the wafer surface after chloride removal treatment according to the embodiment.

[0018] Figure 7 This is a graph showing the relationship between the number of processing steps for the substrate treatment involved in the embodiments and the etching thickness of various materials. Detailed Implementation

[0019] The embodiments of the substrate processing method and substrate processing apparatus disclosed in this application will now be described in detail with reference to the accompanying drawings. Furthermore, this disclosure is not limited to the embodiments shown below. Additionally, the drawings are illustrative, and it should be noted that the dimensional relationships and ratios of the elements may sometimes differ from reality. Furthermore, the drawings may sometimes include portions with different dimensional relationships or ratios from each other.

[0020] In recent years, the requirements for miniaturization in semiconductor device manufacturing processes have become increasingly stringent. To meet these requirements, the development of atomic layer etching (ALE) techniques, which etch materials at the atomic layer level, has been continuously advancing. For example, a technique for atomic layer etching of metal films containing cobalt or copper using a wet process has been disclosed.

[0021] On the other hand, in the aforementioned prior art, there is room for further improvement in the efficient atomic-layer etching of ruthenium-containing metal films, which is being considered for application in semiconductor devices.

[0022] Therefore, it is desirable to develop a technology that can overcome the above-mentioned problems and efficiently perform atomic layer etching on metal films containing ruthenium.

[0023] <Overview of the Substrate Processing System>

[0024] First, refer to Figure 1 The general structure of the substrate processing system 1 according to the embodiment will be described. Figure 1 This is a schematic diagram showing the general structure of the substrate processing system 1 according to the embodiment. Hereinafter, in order to clearly indicate the positional relationship, the X-axis, Y-axis and Z-axis are defined as being orthogonal to each other, and the positive direction of the Z-axis is set as the vertical upward direction.

[0025] Substrate processing system 1 is an example of a substrate processing apparatus. For example... Figure 1As shown, the substrate processing system 1 includes a loading / unloading station 2 and a processing station 3. The loading / unloading station 2 and the processing station 3 are arranged adjacent to each other.

[0026] The loading / unloading station 2 includes a carrier placement section 11 and a transport section 12. The carrier placement section 11 holds multiple carriers C that hold multiple substrates, or in this embodiment, semiconductor wafers W (hereinafter referred to as wafers W), in a horizontal state.

[0027] The transport section 12 is disposed adjacent to the carrier placement section 11, and includes a substrate transport device 13 and a transfer section 14 inside. The substrate transport device 13 includes a wafer holding mechanism for holding the wafer W. In addition, the substrate transport device 13 is capable of moving in the horizontal and vertical directions and rotating about the vertical axis, and uses the wafer holding mechanism to transport the wafer W between the carrier C and the transfer section 14.

[0028] Processing station 3 is arranged adjacent to conveying section 12. Processing station 3 includes conveying section 15 and multiple processing units 16. Multiple processing units 16 are arranged on both sides of conveying section 15.

[0029] The transfer unit 15 includes a substrate transfer device 17 inside. The substrate transfer device 17 includes a wafer holding mechanism for holding the wafer W. In addition, the substrate transfer device 17 is capable of moving in the horizontal and vertical directions and rotating about the vertical axis, and uses the wafer holding mechanism to transfer the wafer W between the transfer unit 14 and the processing unit 16.

[0030] The processing unit 16 performs a prescribed substrate processing on the wafer W transported by the substrate transport device 17.

[0031] Furthermore, the substrate processing system 1 includes a control device 4. The control device 4 is, for example, a computer, and includes a control unit 18 and a storage unit 19. The storage unit 19 stores programs for controlling various processes performed in the substrate processing system 1. The control unit 18 controls the operation of the substrate processing system 1 by reading and executing the programs stored in the storage unit 19.

[0032] Alternatively, the program can be recorded on a computer-readable storage medium and installed from that storage medium into the storage unit 19 of the control device 4. Examples of computer-readable storage media include hard disks (HD), floppy disks (FD), optical disks (CD), magneto-optical disks (MO), and memory cards.

[0033] In the substrate processing system 1 configured as described above, firstly, the substrate transport device 13 of the transport station 2 removes the wafer W from the carrier C placed in the carrier placement section 11 and places the removed wafer W in the transfer section 14. The substrate transport device 17 of the processing station 3 removes the wafer W placed in the transfer section 14 from the transfer section 14 and transports it into the processing unit 16.

[0034] After the wafer W is processed by the processing unit 16, it is removed from the processing unit 16 by the substrate transfer device 17 and placed in the transfer section 14. Then, the processed wafer W placed in the transfer section 14 is returned to the carrier C of the carrier placement section 11 by the substrate transfer device 13.

[0035] <Structure of the Processing Unit>

[0036] Next, refer to Figure 2 The structure of the processing unit 16 will be described. Figure 2 This is a schematic diagram illustrating an example of the specific structure of the processing unit 16 involved in the embodiment. For example... Figure 2 As shown, the processing unit 16 includes a chamber 20, a substrate processing section 30, a liquid supply section 40, and a recovery cup 50.

[0037] The chamber 20 houses the substrate processing unit 30, the liquid supply unit 40, and the recovery cup 50. An FFU (Fan Filter Unit) 21 is installed at the top of the chamber 20. The FFU 21 is used to form a downward flow within the chamber 20.

[0038] The substrate processing unit 30 includes a holding part 31, a support part 32, and a driving part 33, and performs liquid processing on the placed wafer W. The holding part 31 holds the wafer W horizontally. The support part 32 is a member extending in a vertical direction, and its base end is supported by the driving part 33 in a rotatable manner. The holding part 31 is horizontally supported at the front end of the support part 32. The driving part 33 rotates the support part 32 about a vertical axis.

[0039] The substrate processing unit 30 rotates the support portion 32 by using the drive portion 33 to rotate the holding portion 31 supported on the support portion 32, thereby rotating the wafer W held in the holding portion 31.

[0040] A holding member 31a is provided on the upper surface of the holding portion 31 of the substrate processing unit 30 to hold the wafer W from the side. The wafer W is held horizontally by the holding member 31a with its position slightly away from the upper surface of the holding portion 31. Furthermore, the wafer W is held in the holding portion 31 with the surface of the substrate being processed facing upward.

[0041] The liquid supply unit 40 supplies processing fluid to the wafer W. The liquid supply unit 40 includes nozzles 41a and 41b, an arm 42a that horizontally supports the nozzles 41a and 41b, and a rotary lifting mechanism 43a that rotates and raises the arm 42a. Additionally, the liquid supply unit 40 includes nozzles 41c and 41d, an arm 42b that horizontally supports the nozzles 41c and 41d, and a rotary lifting mechanism 43b that rotates and raises the arm 42b.

[0042] Nozzle 41a is connected to first supply unit 46a via valve 44a and flow regulator 45a. The first processing liquid supplied from first supply unit 46a is configured to contain ethyl acetate, acetone or acetonitrile as solvent and trichloroisocyanuric acid (TCCA) as solute. The concentration of trichloroisocyanuric acid in the first processing liquid is, for example, 0.01 wt% to 1.0 wt%.

[0043] Nozzle 41b is connected to the second supply unit 46b via valve 44b and flow regulator 45b. The second processing liquid supplied from the second supply unit 46b is, for example, TMAH (tetramethylammonium hydroxide) or an aqueous solution of choline.

[0044] Nozzle 41c is connected to third supply unit 46c via valve 44c and flow regulator 45c. The third processing liquid supplied from third supply unit 46c is, for example, ethyl acetate, acetone or acetonitrile.

[0045] Nozzle 41d is connected to the fourth supply unit 46d via valve 44d and flow regulator 45d. The flushing fluid supplied from the fourth supply unit 46d is, for example, DIW (Deionized Water).

[0046] The first processing liquid supplied from the first supply unit 46a is ejected from nozzle 41a. The second processing liquid supplied from the second supply unit 46b is ejected from nozzle 41b. The third processing liquid supplied from the third supply unit 46c is ejected from nozzle 41c. The rinsing liquid supplied from the fourth supply unit 46d is ejected from nozzle 41d.

[0047] The recovery cup 50 is located around the holding section 31 and collects the processing liquid that spills from the wafer W due to the rotation of the holding section 31. A drain port 51 is formed at the bottom of the recovery cup 50, and the processing liquid collected by the recovery cup 50 is discharged from the drain port 51 to the outside of the processing unit 16. In addition, an exhaust port 52 is formed at the bottom of the recovery cup 50 for discharging the gas supplied from the FFU 21 to the outside of the processing unit 16.

[0048] <Substrate Processing>

[0049] Next, refer to Figures 3-7 Details of the substrate processing involved in the embodiments will be described. Figure 3 This is a flowchart illustrating an example of the substrate processing procedure involved in the embodiment.

[0050] like Figure 3 As shown, in the substrate processing according to the embodiment, a preparation process (step S101) is first performed. In this preparation process, for example, the surface is prepared to become... Figure 4 The wafer W is shown in the state shown. Figure 4This is an enlarged cross-sectional view showing an example of the state of the prepared wafer W surface according to the embodiment.

[0051] about Figure 4 As shown, firstly, SiO2 is deposited on the surface of wafer W using a known film deposition method. x (Silicon oxide) film, SiCN (silicon carbonitride) film, TiN (titanium nitride) film, Ru (ruthenium) film, SiCN film, SiO x The sequence of membranes forms a thin film.

[0052] Ru film is an example of a metal film. Furthermore, in this disclosure, the Ru film is not limited to being composed solely of ruthenium; it may contain at least ruthenium.

[0053] Next, one or more (multiple in the figure) recesses T are formed on the surface of wafer W using a known etching method. These recesses T are formed from the topmost SiO layer. x The membrane is formed by extending through the TiN membrane. Thus, the preparation process involved in this embodiment is complete.

[0054] Then, in the wafer W after processing is complete, as follows: Figure 4 As shown, multiple residues A are attached to the side of the Ru film exposed in the recess T. These residues A are, for example, residues generated during the etching process that forms the recess T, and are Ru oxides, Ru chlorides, etc. The substrate processing described below is a process primarily aimed at removing these multiple residues A.

[0055] Return to Figure 3 The explanation continues. Following the preparation process described so far, the control unit 18 (refer to...) Figure 1 The count value n used to count the number of times the substrate is processed is set to 1 (step S102).

[0056] In the substrate processing according to the embodiment, a chloride formation process is then performed (step S103). In this chloride formation process, the control unit 18 controls the chloride formation process via the holding unit 31 (see reference 103). Figure 2 After holding wafer W, control the fluid supply unit 40 (refer to...) Figure 2 ) etc. from nozzle 41a (refer to) Figure 2 The first processing solution is supplied to the rotating wafer W.

[0057] Therefore, as Figure 5 As shown, a Ru chloride RuCl3 film forms on the surface of the Ru film exposed in the recess T. Figure 5 This is an enlarged cross-sectional view showing an example of the state of the wafer W surface after the chloride formation treatment involved in the embodiment.

[0058] Ru chloride (RuCl3) is an example of a metal chloride. The Ru chloride (RuCl3) film has an atomic layer thickness, for example, less than 1 nm.

[0059] Thus, in this embodiment, the trichloroisocyanuric acid contained in the first treatment solution reacts with ruthenium in the Ru membrane, thereby forming an atomic-layer-level Ru chloride RuCl3 membrane on the surface of the Ru membrane.

[0060] Furthermore, in this embodiment, the first treatment solution may contain 0.01 wt% to 1.0 wt% trichloroisocyanuric acid. This allows for the efficient formation of atomic-layer-level Ru chloride RuCl3 films on the surface of Ru films.

[0061] Furthermore, in this embodiment, ethyl acetate, acetone, or acetonitrile, which are organic solvents, can be used as the solvent for the first treatment solution. In this way, by using an organic solvent instead of water as the solvent for the first treatment solution, it is possible to suppress unintended water etching of the surface of the Ru film on which the Ru chloride RuCl3 film is formed.

[0062] Return to Figure 3 The following is an explanation. In the substrate processing according to the embodiment, a rinsing process is then performed (step S104).

[0063] In this rinsing process, the control unit 18 controls the fluid supply unit 40, etc., to supply fluid from the nozzle 41c (see reference). Figure 2 Ethyl acetate, acetone, or acetonitrile, which serves as a third processing solution, is supplied to the rotating wafer W after it has been wetted by the first processing solution. As a result, the first processing solution is removed from the surface of the wafer W, and the reaction between the Ru film and the first processing solution ceases.

[0064] Furthermore, in the embodiments, ethyl acetate, acetone, or acetonitrile, as organic solvents, can be used as a third treatment solution in the rinsing process. In this way, by using an organic solvent instead of water in the rinsing process, unintended water etching of the surface of the Ru film on which the Ru chloride RuCl3 film is formed can be suppressed.

[0065] In addition, in this embodiment, ethyl acetate can be used as a third processing solution. This allows the drying process described later to be performed at an appropriate drying rate.

[0066] In the substrate processing according to the embodiment, a drying process is then performed (step S105). In this drying process, the control unit 18 controls the substrate processing unit 30 and the liquid supply unit 40 to stop supplying the third processing liquid from the nozzle 41c, and causes the wafer W to rotate at high speed to remove the third processing liquid. Thus, the wafer W is dried.

[0067] In the substrate processing according to the embodiment, a chloride removal process is then performed (step S106). In this chloride removal process, the control unit 18 controls the substrate processing unit 30 and the liquid supply unit 40, etc., to supply liquid from the nozzle 41b (see reference 106). Figure 2 The rotating wafer W is supplied with TMAH or choline aqueous solution as a second processing solution.

[0068] Therefore, as Figure 6 Remove Ru chloride RuCl3 formed on the surface of the Ru film as shown (refer to...) Figure 5 ) membrane. Figure 6 This is an enlarged cross-sectional view showing an example of the state of the wafer W surface after chloride removal treatment according to the embodiment. Furthermore, as... Figure 6 As shown, the Ru film itself is not etched in the third treatment solution.

[0069] As explained so far, in the substrate processing involved in the embodiments, atomic layer etching of the Ru film can be performed efficiently by using the first processing liquid and the third processing liquid.

[0070] Additionally, in the embodiment, multiple residues A (refer to) adhering to the membrane of Ru chloride RuCl3 Figure 5 It is removed from the Ru membrane along with the Ru chloride RuCl3. Therefore, multiple residues A can be removed efficiently.

[0071] In addition, in the embodiments, the Ru chloride RuCl3 film thickness is at the atomic layer level, thus minimizing damage to the Ru film and suppressing the increase in surface roughness of the Ru film due to etching.

[0072] Additionally, in this embodiment, TMAH or an aqueous solution of choline can be used as a third treatment solution. By using an aqueous solution of TMAH or choline, which does not contain metal elements, as a third treatment solution for removing Ru chloride (RuCl3) from the membrane, it is possible to suppress metal contamination of wafers such as W.

[0073] Return to Figure 3 The following is an explanation. In the substrate processing described in the embodiment, after the chloride removal process described so far, a rinsing process is performed (step S107).

[0074] In this rinsing process, the control unit 18 controls the fluid supply unit 40, etc., to supply fluid from the nozzle 41d (see reference). Figure 2 DIW, which is used as a rinsing solution, is supplied to the rotating wafer W after it has been wetted by the second processing solution. As a result, the second processing solution is removed from the surface of the wafer W.

[0075] In the substrate processing according to the embodiment, a drying process is then performed (step S108). In this drying process, the control unit 18 controls the substrate processing unit 30 and the liquid supply unit 40 to stop supplying rinsing liquid from the nozzle 41d, and causes the wafer W to rotate at high speed to remove the rinsing liquid. Thus, the wafer W is dried.

[0076] In the substrate processing according to the embodiment, the control unit 18 then determines whether the count value n representing the number of times the substrate has been processed is greater than or equal to a given number N (step S109).

[0077] Then, if the count value n is greater than or equal to the given number of times N (step S109, "Yes"), the series of substrate processing ends. On the other hand, if the count value n is not greater than or equal to the given number of times N (step S109, "No"), the control unit 18 increases the count value n representing the number of times the substrate has been processed (step S110) and returns to the processing in step S103.

[0078] Thus, in this embodiment, steps S103 to S108 can be repeated sequentially. This allows for the high-precision etching of the Ru film surface to achieve the desired thickness.

[0079] Additionally, in this embodiment, the Ru film can be located on SiO. x The substrate is applied to at least one of the following films: a SiCN film, a SiN (silicon nitride) film, a SiOC (silicon oxycarbide) film, and a TiN film. Therefore, through the substrate processing described in the embodiments, SiO2 can be suppressed. x At least one of the following films—a film, a SiCN film, a SiN film, a SiOC film, and a TiN film—is etched together with the Ru film.

[0080] Figure 7 This is a graph showing the relationship between the number of substrate processing steps involved in the embodiments and the etching thickness of various materials. Furthermore, in Figure 7 In the example, a treatment solution containing 1.0 wt% trichloroisocyanuric acid in ethyl acetate was used as the first treatment solution, ethyl acetate was used as the second treatment solution, and 1 mol / L TMAH was used as the third treatment solution. Additionally, in Figure 7 In the example, the temperature of each treatment solution was room temperature.

[0081] like Figure 7 As shown, in the substrate processing described in the embodiment, the amount of Ru etched increases linearly with the number of processing cycles. On the other hand, it is known that in SiO... x In the cases of SiCN, SiN, SiOC and TiN, even with an increase in the number of processing steps, the etching amount hardly increases.

[0082] That is, in the substrate processing involved in the embodiments, it is possible to selectively process only Ru and SiO. x Etching is performed on Ru in SiCN, SiN, SiOC, and TiN. Therefore, according to the embodiment, in... Figure 4 In the device structure shown, only the Ru film can be selectively etched, thus maintaining the device structure well.

[0083] The substrate processing method according to the embodiment includes a formation step (step S103) and a removal step (step S106). In the formation step (step S103), the surface of a ruthenium-containing metal film (Ru film) is treated with a first processing solution to form a metal chloride (Ru chloride RuCl3) on the surface of the metal film (Ru film). In the removal step (step S106), the metal chloride (Ru chloride RuCl3) is removed using a second processing solution. This allows for efficient atomic-level etching of the Ru film.

[0084] Furthermore, in the substrate processing method described in the embodiment, the first processing solution contains 0.01 wt% to 1.0 wt% trichloroisocyanuric acid. This allows for the efficient formation of an atomic-layer-level Ru chloride RuCl3 film on the surface of the Ru film.

[0085] Furthermore, in the substrate processing method described in the embodiments, the solvent of the first processing liquid is ethyl acetate, acetone, or acetonitrile. This prevents unintended water etching of the surface of the Ru film on which the Ru chloride (RuCl3) film is formed.

[0086] Furthermore, in the substrate processing method described in the embodiments, the metal film (Ru film) is located on SiO. x The device structure on the wafer W can be well maintained by applying at least one of the following films: SiCN film, SiN film, SiOC film, and TiN film.

[0087] Furthermore, in the substrate processing method described in the embodiment, the second processing solution is TMAH or an aqueous solution of choline. This helps to suppress contamination of the wafer W by metal elements.

[0088] Furthermore, the substrate processing method according to the embodiment also includes a rinsing step (step S104) and a drying step (step S105). The rinsing step (step S104) is performed after the formation step (step S103), and in this step, the surface of the metal chloride (Ru chloride RuCl3) is rinsed using a third processing solution. The drying step (step S105) is performed after the rinsing step (step S104), and in this step, the surface of the metal chloride (Ru chloride RuCl3) is dried. This allows for the suppression of excessive Ru chloride RuCl3 film thickness formation on the surface of the Ru film.

[0089] Furthermore, in the substrate processing method described in the embodiments, the third processing liquid is ethyl acetate, acetone, or acetonitrile. This prevents unintended water etching of the surface of the Ru film on which the Ru chloride (RuCl3) film is formed.

[0090] Furthermore, in the substrate processing method described in the embodiment, the forming process (step S103) and the removal process (step S106) are performed sequentially and repeatedly. This allows for high-precision etching of the Ru film surface to achieve the desired thickness.

[0091] Furthermore, in the substrate processing method described in the embodiment, the thickness of the metal chloride (Ru chloride RuCl3) film is 1 nm or less. This minimizes damage to the Ru film and suppresses the increase in the surface roughness of the Ru film.

[0092] Furthermore, the substrate processing apparatus according to the embodiment includes a holding section 31, a liquid supply section 40, and a control section 18. The holding section 31 holds a substrate (wafer W) on which a metal film containing ruthenium (Ru film) is formed and rotates the substrate. The liquid supply section 40 supplies processing liquid to the substrate (wafer W) held in the holding section 31. The control section 18 controls each section. In addition, the control section 18 performs the following control: treating the surface of the metal film (Ru film) with a first processing liquid to form a metal chloride (Ru chloride RuCl3) on the surface of the metal film (Ru film); and removing the metal chloride (Ru chloride RuCl3) with a second processing liquid. As a result, atomic layer etching of the Ru film can be performed efficiently.

[0093] The embodiments of this disclosure have been described above, but this disclosure is not limited to the above embodiments. Various modifications can be made as long as they do not depart from its spirit. For example, in the above embodiments, a modification of... Figure 4 The wafer W with the surface structure shown is an example of the application of the techniques disclosed herein, but the disclosure is not limited to this example.

[0094] For example, the technique disclosed herein can also be applied to a Ru film embedded in a recess formed on wafer W, with its upper surface exposed. This allows for efficient atomic-level etching of the Ru film.

[0095] The embodiments disclosed herein should be considered illustrative in all respects, not restrictive. In fact, the above embodiments can be implemented in various ways. Furthermore, the above embodiments can be omitted, substituted, or modified in various ways without departing from the appended claims and their spirit.

[0096] Explanation of reference numerals in the attached figures

[0097] W: Wafer (an example of a substrate); 1: Substrate processing system (an example of a substrate processing apparatus); 18: Control unit; 31: Holding unit; 40: Liquid supply unit.

Claims

1. A substrate processing method, comprising the following steps: The surface of a ruthenium-containing metal film is treated with a first treatment solution to form a metal chloride on the surface of the metal film; as well as The metal chloride is removed using a second treatment solution.

2. The substrate processing method according to claim 1, wherein, The first treatment solution contains 0.01wt% to 1.0wt% trichloroisocyanuric acid.

3. The substrate processing method according to claim 2, wherein, The solvent for the first treatment solution is ethyl acetate, acetone, or acetonitrile.

4. The substrate processing method according to any one of claims 1 to 3, wherein, The metal film is located in SiO x It is applied to at least one of the following films: a SiCN film, a SiN film, a SiOC film, and a TiN film.

5. The substrate processing method according to any one of claims 1 to 3, wherein, The second treatment solution is tetramethylammonium hydroxide (TMAH) or an aqueous solution of choline.

6. The substrate processing method according to any one of claims 1 to 3, wherein, It also includes the following processes: After the formation process is completed, the surface of the metal chloride is rinsed with a third treatment solution. as well as After the rinsing process, the surface of the metal chloride is dried.

7. The substrate processing method according to claim 6, wherein, The third treatment solution is ethyl acetate, acetone, or acetonitrile.

8. The substrate processing method according to any one of claims 1 to 3, wherein, The forming process and the removal process are repeated sequentially.

9. The substrate processing method according to any one of claims 1 to 3, wherein, The thickness of the metal chloride film is less than 1 nm.

10. A substrate processing apparatus comprising: A holding section that holds a substrate having a metal film containing ruthenium formed on it and rotates the substrate; A liquid supply unit supplies processing liquid to the substrate held in the holding unit; and The control department controls all other departments. in, The control unit performs the following controls: The surface of the metal film is treated with a first treatment solution to form a metal chloride on the surface of the metal film; and The metal chloride is removed using a second treatment solution.

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