JP7813604B2 - Substrate processing solution, substrate processing method, and substrate processing apparatus - Google Patents

Description

This invention relates to a substrate processing solution for etching substrates having trench structures, a substrate processing method for processing substrates with the substrate processing solution, and a substrate processing apparatus.

Manufacturing processes for electronic components such as semiconductor devices and liquid crystal display devices include an etching process in which a substrate is partially etched away to form a desired pattern. For example, Patent Document 1 (JP-A-2005-102626) describes a manufacturing process for a fin-type field-effect transistor (hereinafter referred to as "FinFET"). In this FinFET, a gate is formed across multiple fins. Specifically, an HKMG layer is formed on the multiple fins, followed by a gate material layer. The HKMG layer is a stack of a high-k metal gate layer (HK) made of a high-k dielectric such as _HfO2 , _Al2O3 , _{or La2O3} , and _a metal layer (MG) made of TiN, TaN, TaAlN, or TiC. In Patent Document 1, reactive ion etching (RIE) is used to pattern the HKMG layer.

Special Publication No. 2015-536581 (Paragraph 0016)

In recent years, the use of wet etching has been considered for the manufacture of electronic components such as the aforementioned FinFETs and three-dimensional NAND nonvolatile semiconductor devices (hereinafter referred to as "3D-NAND memory"). However, with the advancement of finer patterns and more complex three-dimensional structures, the need for etching in confined areas has arisen. For example, to form the metal layer of a FinFET, as shown in Figure 1 (described later), a TiN layer must be formed on the fin using a material that constitutes the metal layer, such as TiN, and then the TiN layer must be partially removed using an etching solution to achieve the desired shape. The TiN layer formed across multiple fins has a trench structure. Therefore, to achieve the desired shape, an etchant must be introduced into the trench structure to etch the TiN layer. However, as the fin pitch of FinFETs becomes narrower, the opening of the trench structure becomes narrower, resulting in a confined space within the trench structure. This makes it difficult to efficiently introduce the etchant, resulting in a reduced etching rate within the confined space. As a result, there was a problem in that the metal layer could not be finished into the desired shape. This problem is not limited to cases where the bottom wall that constitutes a trench structure, such as a FinFET, and one or more side walls extending from the bottom wall toward the opening are all subject to etching, but also occurs when only the bottom wall, or all or part of the side walls, are subject to etching.

This invention was developed in consideration of the above-mentioned problems, and aims to provide a substrate processing solution, a substrate processing method, and a substrate processing apparatus that can perform etching processing at an excellent etching rate on substrates in which at least one of the bottom wall and sidewalls that form a trench structure is an etched layer composed of a metal or a compound of that metal.

A first aspect of the present invention is a substrate processing solution that is supplied to a substrate having a trench structure, in which a narrow space is formed by an opening having a narrow width, a bottom wall opposing the opening, and one or more side walls extending from the bottom wall toward the opening, and in which at least one of the bottom wall and the side walls is formed of an etching layer of a metal or a compound of the metal, to remove the etching layer, and is characterized by comprising a chemical solution containing H ₂ O ₂ molecules or HO ₂ ^- that functions as an etchant for etching the metal, and a first complex-forming agent containing anions that form a complex with ions of the metal, and is adjusted to a pH of 1 or more and a pH of 3 or less.

A second aspect of the present invention is a substrate processing method, comprising the steps of: supplying a substrate processing liquid to a substrate having a trench structure in which a narrow space is formed by an opening having a narrow width, a bottom wall opposing the opening, and one or more side walls extending from the bottom wall toward the opening, and in which at least one of the bottom wall and the side walls is formed by an etching layer composed of a metal or a compound of the metal; and removing the substrate processing liquid from the substrate to stop removal of the etching layer, wherein the substrate processing liquid comprises a chemical solution containing H ₂ O ₂ molecules or HO ₂ ⁻ that functions as an etchant for etching the metal, and a first complex-forming agent containing anions that form a complex with ions of the metal, and is adjusted to a pH of 1 or more and a pH of 3 or less.

A third aspect of the present invention is a substrate processing apparatus comprising: a substrate holding unit that holds a substrate having a trench structure in which a narrow space is formed by an opening having a narrow width, a bottom wall facing the opening, and one or more side walls extending from the bottom wall toward the opening, and at least one of the bottom wall and the side walls is formed by an etching layer composed of a metal or a compound of the metal; and a processing liquid supply unit that supplies a substrate processing liquid to the substrate held by the substrate holding unit, wherein the substrate processing liquid comprises a chemical solution containing H ₂ O ₂ molecules or HO ₂ ^- that functions as an etchant to etch the metal, and a first complex forming agent containing anions that form a complex with ions of the metal, and is adjusted to a pH of 1 or more and pH 3 or less.

According to the invention configured in this way, a chemical solution containing H ₂ O ₂ molecules or HO ₂ ^- that functions as an etchant for etching metal and a first complex-forming agent containing anions that form a complex with metal ions are provided, and the pH is adjusted to between 1 and 3. Therefore, an etching process can be performed at an excellent etching rate on a substrate in which at least one of the bottom wall and side wall that form a trench structure is an etched layer composed of a metal or a compound of that metal.

1A to 1C are diagrams schematically illustrating an embodiment of a substrate processing method according to the present invention. 1 is a graph showing the change in zeta potential of Si, PSL, Si ₃ N ₄ , and SiO ₂ with respect to pH. 2 is a diagram showing a first embodiment of a substrate processing apparatus capable of performing the substrate processing method shown in FIG. 1; FIG. FIG. 4 is a side view of the substrate processing apparatus shown in FIG. 3 . FIG. 2 is a partial cross-sectional view showing the configuration of a processing unit. FIG. 2 is a block diagram showing the electrical configuration of a control unit that controls the processing unit. FIG. 2 is a diagram showing a configuration of a substrate processing liquid supply unit. 4A to 4C are diagrams showing the contents of substrate processing performed in the substrate processing apparatus of FIG. 3. 1A and 1B are diagrams schematically illustrating the configuration of a sample for evaluating an etching rate and the details of an experiment. 1 is a graph showing the etching characteristics of substrate processing solutions (1) to (5). 10 is a graph showing the etching characteristics of substrate processing solutions (4) to (7).

<Summary of the Invention>
The present invention relates to a substrate processing method and substrate processing apparatus that wet-etches at least one of the bottom wall and sidewall of a trench structure formed in a substrate, using the layer to be etched as a target layer by supplying a substrate processing solution to the substrate, and to a substrate processing solution that effectively performs the etching. In particular, in the substrate processing method according to the present invention, the target layer is composed of a metal or a metal compound, and the etching process is performed using a chemical solution containing H ₂ O ₂ molecules or HO ₂ ⁻ that functions as an etchant for etching the metal. For example, a hydrogen peroxide solution (Comparative Example 2, which will be described later) can be used as the chemical solution. Furthermore, the substrate processing method corresponds to one step in manufacturing a gate of a FinFET, as shown in FIG. 1 .

Figure 1 is a schematic diagram illustrating one embodiment of a substrate processing method according to the present invention. To manufacture a FinFET gate, as described in Patent Document 1, a metal layer 12 such as TiN, TaN, TaAlN, or TiC is deposited to a desired thickness on a high-k dielectric layer 11 formed across multiple fins F extending upward from a substrate W such as silicon (see the bottom drawing (b) of Figure 1). The high-k dielectric layer 11 and metal layer 12 form an HKMG layer 13. A gate material layer (not shown) such as polysilicon is then formed on the HKMG layer 13. This completes the manufacture of the FinFET gate.

Here, the metal layer 12 is formed in two stages. That is, as shown in the upper diagram (a) of Figure 1, a metal layer thicker than the desired thickness, such as a TiN layer 12a, is formed on the high-k dielectric layer 11 by metal vapor deposition or the like. After this TiN layer 12a is formed, a substrate processing liquid is supplied to the surface of the substrate W, and the TiN layer 12a is wet-etched to form a metal layer 12 of the desired thickness, as shown in the lower diagram (b) of the same figure.

It is important to note here that the TiN layer 12a is formed to conform to the shape of the fin F, forming a narrow trench structure between adjacent fins F. Because the TiN layer 12a is relatively thick, the opening 12c of the trench structure is significantly narrower than the fin pitch Pf. In other words, the opening dimension OW of the opening 12c is the narrow width. The bottom wall 12d and sidewall 12e that form the trench structure also have the following characteristics: The bottom wall 12d facing the opening 12c is narrow, and the distance between the sidewall 12e extending from the bottom wall 12d toward the opening 12c is also less than the opening dimension OW. Therefore, the internal space of the trench structure is significantly narrower than the space formed by adjacent fins F, forming a so-called narrow space 12f. Therefore, simply using a substrate processing solution primarily composed of a hydrogen peroxide solution makes it difficult to efficiently introduce an etchant into the narrow space 12f. As a result, a decrease in the etching rate of the TiN layer 12a that forms the bottom wall 12d and sidewall 12e of the trench structure was unavoidable. Note that in this specification, "narrow width" means 2 nm or more and 10 nm or less.

Therefore, the present inventors have conducted extensive research and have found that adding a complex-forming agent containing complex-forming ions to the substrate processing solution is effective in promoting the formation of complexes in the narrow space 12f, in other words, promoting the dissolution of the layer to be etched. Based on this finding, the present inventors have invented a substrate processing solution that uses NH ₄ ⁺ as a complex-forming ion, as described in JP 2021-145009 A.

On the other hand, in addition to NH ₄ ⁺ , halogen ions such as Cl ^- are also considered as candidates for the complex-forming ions, and this is what we focused on in this study. When part of the wall surface forming the trench structure is made of Si or SiO ₂ , as shown in Figure 9, which will be explained later, the potential of the wall surface is greatly affected by the pH.

Figure 2 is a graph showing the change in zeta potential of Si, PSL, Si ₃ N ₄ , and SiO ₂ versus pH. The source of this graph is T. Hattori: Ultraclean Surface Processing of Silicon Wafers, 119 (1998), where "Si" refers to silicon, "PSL" refers to polystyrene latex, "Si ₃ N ₄ " refers to silicon nitride, and "SiO ₂ " refers to silicon dioxide. As is clear from the graph, in the neutral to alkaline range, the narrow interface is negatively charged, which is thought to result in a decrease in liquid replacement efficiency and the inhibition of etchant ion penetration due to an electric double layer. In contrast, in the acidic range below pH 6, the zeta potential of Si and SiO ₂ increases, and the narrow interface also becomes positively charged or approaches a positive charge. This is thought to facilitate the penetration of HO ^2- etchant ions into narrow spaces. However, the more acidic the solution, the lower the concentration of etchant ions in the substrate processing solution. More specifically, as will be shown in the examples and comparative examples described later, when the pH is below 1, the penetration of etchant ions into narrow spaces increases, but the effect of penetration is canceled out by a decrease in the etchant ion concentration. Therefore, when using anionic complex-forming ions, it is important to adjust the pH of the substrate processing solution to at least 1 and 6 inclusive in order to increase the etching rate.

A mixed solution (Comparative Example 2, described later) of aqueous hydrogen peroxide and deionized water (DIW) in a 1:5 ratio has a pH of approximately 5. Adding hydrochloric acid (HCl) to the mixed solution as the first complex-forming agent of the present invention results in the inclusion of Cl ⁻ (complex-forming ions) in the substrate processing solution, further lowering the pH of the substrate processing solution. However, if the mixing ratio of hydrochloric acid, aqueous hydrogen peroxide, and DIW in the substrate processing solution is 1:1:5, the pH of the substrate processing solution (Comparative Example 1, described later) falls below 1. Therefore, it is desirable to adjust the mixing ratio of hydrochloric acid in the substrate processing solution to 0.1 or less, with a more preferred range being 0.001 to 0.1 (Examples 1 to 3, described later). Furthermore, these effects can also be achieved when using a first complex-forming agent containing anions other than Cl ⁻ , such as halogen ions, that form complexes with metal ions (Ti in this embodiment).

As described above, when fabricating the HKMG layer 13 of a FinFET, the substrate processing solution used to etch the TiN layer 12a constituting the bottom wall 12d and sidewall 12e of the trench structure can be a chemical solution containing an etchant such as H _{O 2} molecules or HO ₂ ^{− .} However, it is preferable to add a first complexing agent and adjust the pH. That is, by adding a complexing agent containing an anion that forms a complex with a metal (Ti in this embodiment) ion and adjusting the pH of the substrate processing solution to 1 or more and 6 or less, the amount of etchant can be increased and the etchant can be efficiently introduced into the trench structure, i.e., into the narrow space 12f. Therefore, the TiN layer 12a (the layer to be etched) constituting the bottom wall 12d and sidewall 12e can be etched at an excellent etching rate. As a result, a high-performance FinFET can be fabricated.

Furthermore, since NH ₄ ⁺ can be used as a complex-forming ion as described above, a second complex-forming agent containing such a cation may be added. This second complex-forming agent may be a compound having the general formula (NH ₄ ⁺ ) _n X ^n- , which contains ammonium ion NH ₄ ⁺ .
where X ^n- is an n-valent anion, n is 1 or 2;
As the ammonium salt, an ammonium salt represented by the following formula can be used:
・Ammonium Fluoride NH4F
・Ammonium chloride NH4Cl (Ammonium Chloride)
・Ammonium bromide NH4Br (Ammonium Bromide)
・Ammonium iodide NH4I (Ammonium Iodide)
・Ammonium sulfide (NH4)2SO4 (Ammonium Sulfide)
・Ammonium acetate NH4CH3CO2 (Ammonium Acetate)
・Ammonium phosphate (NH4)2PO4 (Ammonium Phosphate)
Includes:

Alternatively, alkylammonium salts can be used as the second complex-forming agent. Examples of alkylammonium salts include quaternary ammonium salts represented by the general formula (NR4 ⁺ ) _n X ^n- , tertiary amines represented by R3N, secondary amines represented by R2NH, and primary amines represented by RNH2 (where R is an alkyl group or an aryl group), for example:
Tetramethylammonium fluoride [(CH3)4N]F (TetraMethylAmmonium Fluoride; TMAF)
Tetraethylammonium fluoride [(CH3CH2CH2)4N]F (TetraEthylAmmonium Fluoride; TEAF)
Tetrabutylammonium fluoride [(CH3CH2CH2CH2CH2)4N]F (TetraButylAmmonium Fluoride; TBAF)
Tetramethylammonium chloride [(CH3)4N]Cl (TetraMethylAmmonium Chloride; TMAC)
Tetraethylammonium chloride [(CH3CH2CH2)4N]Cl (TetraEthylAmmonium Chloride; TEAC)
Tetrabutylammonium chloride [(CH3CH2CH2CH2CH2)4N]Cl (TetraButylAmmonium Chloride; TBAC)
Tetramethylammonium iodide [(CH3)4N]I (TetraMethylAmmonium Iodide; TMAI)
Tetraethylammonium iodide [(CH3CH2CH2)4N]I (TetraEthylAmmonium Iodide; TEAI)
Tetrabutylammonium iodide [(CH3CH2CH2CH2CH2)4N]I (TetraButylAmmonium Iodide; TBAI)
hydrogen sulfates such as tetrabutylammonium hydrogen sulfate; acetates such as tetramethylammonium acetate; hydroxides such as tetraethylammonium hydroxide; perchlorates such as tetrabutylammonium perchlorate; and the like.

By adding the second complex-forming agent described above as needed, complex formation in narrow spaces is promoted, facilitating the dissolution of the material to be etched. Note that, to distinguish this type of second complex-forming agent containing a cation, which is added as needed, from the first complex-forming agent, such as hydrochloric acid, which is used regularly, it will be referred to below as an "additional complex-forming agent."

<Substrate Processing Apparatus>
Next, the construction and operation of a substrate processing apparatus for performing the substrate processing method shown in FIG. 1 using the substrate processing solution will be described with reference to FIGS.

Figure 3 is a diagram showing a first embodiment of a substrate processing apparatus capable of performing the substrate processing method shown in Figure 1. Figure 4 is a side view of the substrate processing apparatus shown in Figure 3. This substrate processing apparatus 100 is an apparatus that performs an etching process on the substrate W shown in the upper part of Figure 1 using the substrate processing liquid described above. These drawings do not show the external appearance of the apparatus, but are schematic diagrams that clearly show the internal structure of the substrate processing apparatus 100 by excluding the outer wall panels and other components. This substrate processing apparatus 100 is a single-wafer processing apparatus that is installed, for example, in a clean room and performs an etching process on substrates W for manufacturing FinFETs to form the metal layer of the HKMG layer (reference numeral 12 in Figure 1).

In this embodiment, to etch the TiN layer 12a in the upper drawing of Figure 1 to form the metal layer 12, a substrate processing solution prepared by mixing hydrochloric acid, which functions as a complexing agent, a hydrogen peroxide solution (chemical solution) containing an etchant, and DIW in a ratio of 0.1:1:5 is used as the etching solution. The pH of the substrate processing solution prepared in this manner is approximately 2. Note that this substrate processing solution corresponds to "Example 2" described later, but other substrate processing solutions such as those shown in "Example 1," "Example 3," "Example 4," and "Example 5" may also be used.

As shown in FIG. 3, the substrate processing apparatus 100 comprises a substrate processing unit 110 that processes substrates W, and an indexer unit 120 coupled to the substrate processing unit 110. The indexer unit 120 comprises a container holder 121 that can hold a plurality of containers C for accommodating substrates W (such as FOUPs (Front Opening Unified Pods), SMIF (Standard Mechanical Interface) pods, and OCs (Open Cassettes) that accommodate a plurality of substrates W in a sealed state), and an indexer robot 122 that accesses the containers C held by the container holder 121 to remove unprocessed substrates W from the container C and store processed substrates W into the container C. Each container C accommodates a plurality of substrates W in a substantially horizontal position.

The indexer robot 122 comprises a base 122a fixed to the device housing, an articulated arm 122b rotatable about a vertical axis relative to the base 122a, and a hand 122c attached to the tip of the articulated arm 122b. The hand 122c is structured so that a substrate W can be placed on and held on its upper surface. Indexer robots having such articulated arms and hands for holding substrates are well known, so a detailed description will be omitted.

The substrate processing section 110 comprises a substrate transfer robot 111 located approximately in the center in a plan view, and multiple processing units 1 arranged to surround the substrate transfer robot 111. Specifically, multiple processing units 1 (eight in this example) are arranged facing the space in which the substrate transfer robot 111 is located. The substrate transfer robot 111 randomly accesses these processing units 1 to hand over substrates W. Meanwhile, each processing unit 1 performs a predetermined process on the substrate W. In this embodiment, these processing units 1 have the same functions. This makes it possible to process multiple substrates W in parallel.

Figure 5 is a partial cross-sectional view showing the configuration of a processing unit. Figure 6 is a block diagram showing the electrical configuration of a control unit that controls the processing units. In this embodiment, a control unit 4 is provided for each processing unit 1, but multiple processing units 1 may also be controlled by a single control unit. Alternatively, the processing units 1 may be controlled by a control unit (not shown) that controls the entire substrate processing apparatus 100.

The processing unit 1 includes a chamber 2 having an internal space 21 and a spin chuck 3 accommodated in the internal space 21 of the chamber 2 and functioning as a substrate holder for holding a substrate W. As shown in FIGS. 3 and 4 , a shutter 23 is provided on the side of the chamber 2. A shutter opening/closing mechanism 22 ( FIG. 6 ) is connected to the shutter 23, and opens and closes the shutter 23 in response to an opening/closing command from the control unit 4. More specifically, in the processing unit 1, when an unprocessed substrate W is loaded into the chamber 2, the shutter opening/closing mechanism 22 opens the shutter 23, and the unprocessed substrate W is loaded face-up onto the spin chuck 3 by the hand of the substrate transfer robot 111. In other words, the substrate W is placed on the spin chuck 3 with the TiN layer 12a ( FIG. 1 ) facing upward. After the substrate is loaded, when the hand of the substrate transfer robot 111 retreats from the chamber 2, the shutter opening/closing mechanism 22 closes the shutter 23. Then, as described below, a substrate processing liquid, DIW, and nitrogen gas are supplied to the surface Wf of the substrate W within the internal space 21 of the chamber 2, and the desired substrate processing is carried out in a room temperature environment. After the substrate processing is completed, the shutter opening/closing mechanism 22 reopens the shutter 23, and the hand of the substrate transport robot 111 removes the processed substrate W from the spin chuck 3. In this manner, in this embodiment, the internal space 21 of the chamber 2 functions as a processing space for performing substrate processing while maintaining a room temperature environment. Note that in this specification, "room temperature" means a temperature range of 5°C to 35°C.

The spin chuck 3 includes a plurality of chuck pins 31 for gripping the substrate W, a spin base 32 formed in a horizontally disk-like shape and supporting the plurality of chuck pins 31, a central shaft 33 connected to the spin base 32 and rotatable about a rotation axis C1 parallel to a surface normal extending from the center of the surface of the substrate W, and a substrate rotation drive mechanism 34 that rotates the central shaft 33 about the rotation axis C1 using a motor. The plurality of chuck pins 31 are provided on the periphery of the upper surface of the spin base 32. In this embodiment, the chuck pins 31 are arranged at equal intervals in the circumferential direction. When the motor of the substrate rotation drive mechanism 34 is activated in response to a rotation command from the control unit 4 while the substrate W placed on the spin chuck 3 is gripped by the chuck pins 31, the substrate W rotates about the rotation axis C1. Furthermore, while the substrate W is being rotated in this manner, substrate processing liquid, DIW, and nitrogen gas are sequentially supplied to the surface Wf of the substrate W from nozzles provided in the atmosphere blocking mechanism 5 in response to supply commands from the control unit 4.

The atmosphere shutoff mechanism 5 includes a shutoff plate 51, an upper spin shaft 52 rotatable integrally with the shutoff plate 51, and a nozzle 53 that vertically penetrates the center of the shutoff plate 51. The shutoff plate 51 is finished in a circular disk shape with a diameter approximately the same as or greater than that of the substrate W. The shutoff plate 51 is disposed opposite, with a gap between them, to the upper surface of the substrate W held by the spin chuck 3. Therefore, the lower surface of the shutoff plate 51 functions as a circular substrate-facing surface 51a that faces the entire front surface Wf of the substrate W. Furthermore, a cylindrical through-hole 51b that vertically penetrates the shutoff plate 51 is formed in the center of the substrate-facing surface 51a.

The upper spin shaft 52 is rotatably mounted about a rotation axis (coincident with the rotation axis C1 of the substrate W) that passes through the center of the shielding plate 51 and extends vertically. The upper spin shaft 52 has a cylindrical shape. The inner circumferential surface of the upper spin shaft 52 is formed into a cylindrical surface centered on the rotation axis. The internal space of the upper spin shaft 52 communicates with the through-hole 51b of the shielding plate 51. The upper spin shaft 52 is supported by a support arm 54 that extends horizontally above the shielding plate 51 so as to be rotatable relative to the support arm 54.

The nozzle 53 is positioned above the spin chuck 3. The nozzle 53 is supported by the support arm 54 in a state where it cannot rotate relative to the support arm 54. The nozzle 53 can be raised and lowered integrally with the shielding plate 51, upper spin shaft 52, and support arm 54. An outlet 53a is provided at the lower end of the nozzle 53, and faces the center of the front surface Wf of the substrate W held by the spin chuck 3.

A shielding plate rotation drive mechanism 55 (Figure 6), which includes an electric motor and other components, is coupled to the shielding plate 51. The shielding plate rotation drive mechanism 55 rotates the shielding plate 51 and the upper spin shaft 52 about the rotation axis C1 relative to the support arm 54 in response to a rotation command from the control unit 4. A shielding plate lift drive mechanism 56 is also coupled to the support arm 54. The shielding plate lift drive mechanism 56 raises and lowers the shielding plate 51, the upper spin shaft 52, and the nozzle 53 together with the support arm 54 in the vertical direction Z in response to a lift command from the control unit 4. More specifically, the shielding plate lift drive mechanism 56 raises and lowers the substrate-facing surface 51a between a blocking position (position shown in Figure 3) where the substrate-facing surface 51a is close to the front surface Wf of the substrate W held on the spin chuck 3 and substantially blocks the space above the front surface Wf from the surrounding atmosphere, and a retracted position (not shown) that is retracted significantly above the blocking position.

The upper end of the nozzle 53 is connected to a processing liquid supply control unit 61, a DIW supply control unit 62, and a gas supply control unit 63.

The processing liquid supply control unit 61 has a processing liquid pipe 611 connected to the nozzle 53 and a valve 612 inserted in the processing liquid pipe 611. The processing liquid pipe 611 is connected to the processing liquid supply unit 400, which functions as a supply source of substrate processing liquid.

Figure 7 shows the configuration of the substrate processing liquid supply unit. The processing liquid supply unit 400 includes a chemical liquid supply system 410 that supplies an etchant-containing hydrogen peroxide solution (chemical liquid), a DIW supply system 420 that supplies DIW, and a complexing agent supply system 430 that supplies hydrochloric acid, an example of a first complexing agent. The chemical liquid supply system 410 temporarily stores the hydrogen peroxide solution replenished from a hydrogen peroxide solution supply source in a tank 411 and supplies it to the mixing valve 450 at the appropriate timing. The chemical liquid supply system 410 includes a pipe 412 that connects the tank 411 to a nitrogen gas supply source. A flow control valve 413 and an on/off control valve 414 are installed in this pipe 412. Therefore, by operating in response to commands from the control unit 4 (Figure 6), nitrogen gas is pressure-fed to the tank 411 at an appropriate flow rate via the flow control valve 413 and the on/off control valve 414. This allows the aqueous hydrogen peroxide solution stored in tank 411 to be supplied to mixing valve 450 via piping 415. Pipe 415 is also equipped with a flow rate adjustment valve 416 and an on/off control valve 417. Flow rate adjustment valve 416 and on/off control valve 417 operate in response to commands from control unit 4, allowing the aqueous hydrogen peroxide solution to be supplied to mixing valve 450 at an appropriate flow rate and with appropriate timing. Meanwhile, to maintain a constant level of aqueous hydrogen peroxide solution stored in tank 411, a sensor 418 is provided that detects the liquid level of the aqueous hydrogen peroxide solution in tank 411. Sensor 418 detects the liquid level, and based on the detection result, aqueous hydrogen peroxide solution is replenished from the supply source to tank 411.

The DIW supply system 420 has a pipe 421 connecting the DIW supply source to the mixing valve 450, and a flow rate adjustment valve 422 and an on-off control valve 423 are installed in the pipe 421. Therefore, the flow rate adjustment valve 422 and the on-off control valve 423 operate in response to commands from the control unit 4, and DIW is supplied to the mixing valve 450 at an appropriate flow rate and at the appropriate timing.

The complexing agent supply system 430 temporarily stores hydrochloric acid in a tank 431 and supplies it to the mixing valve 450 at appropriate times. The complexing agent supply system 430 has a pipe 432 connecting the tank 431 to a hydrochloric acid supply source. A flow rate adjustment valve 433 and an on/off control valve 434 are installed in this pipe 432. A sensor 435 is also provided to detect the hydrochloric acid level in the tank 431 in order to maintain a constant level of hydrochloric acid stored in the tank 431. The sensor 435 detects the level, and based on the detection result, the flow rate adjustment valve 433 and on/off control valve 434 operate to replenish hydrochloric acid from the hydrochloric acid supply source to the tank 431.

The tank 431 and the nitrogen gas supply source are connected by piping 436. A flow rate adjustment valve 437 and an on/off control valve 438 are installed in this piping 436. Therefore, by operating in response to commands from the control unit 4, nitrogen gas is pressurized into the tank 431 via the flow rate adjustment valve 437 and the on/off control valve 438 at an appropriate flow rate, and hydrochloric acid stored in the tank 431 can be supplied to the mixing valve 450 via piping 439. A flow rate adjustment valve 440 and an on/off control valve 441 are installed in this piping 439. Therefore, by operating the flow rate adjustment valve 440 and the on/off control valve 441 in response to commands from the control unit 4, hydrochloric acid is supplied to the mixing valve 450 at an appropriate flow rate and at the appropriate timing.

Appropriate amounts of aqueous hydrogen peroxide solution, DIW, and hydrochloric acid are supplied to the mixing valve 450 and mixed there. The mixed solution is then sent to another tank 461 via piping 451. This tank 461 is connected to a supply source of an additional complexing agent (ammonium chloride in this embodiment) via piping 462. Therefore, in response to a command from the control unit 4, the additional complexing agent is added from this supply source to the substrate processing solution stored in the tank 461, thereby producing the substrate processing solution of Example 4, which will be described later. Here, ammonium chloride, an example of an additional complexing agent, is a powder solid at room temperature. Therefore, as shown in FIG. 7 , an agitation unit 463 is provided within the tank 461 to promote dissolution and mixing of the ammonium chloride through agitation. On the other hand, when the addition of the additional complexing agent is stopped, the mixed solution of aqueous hydrogen peroxide solution, DIW, and hydrochloric acid is stored in the tank 461 as the substrate processing solution of Example 2.

Tank 461 is also connected to a nitrogen gas supply source via pipe 464. Pipe 464 is also equipped with a flow rate adjustment valve 465 and an on/off control valve 466. Therefore, by operating in response to commands from control unit 4, nitrogen gas is pressure-fed to tank 461 via flow rate adjustment valve 465 and on/off control valve 466 at an appropriate flow rate, and the substrate processing liquid mixed in tank 461 is delivered via pipe 467. Pipe 467 is also equipped with a flow rate adjustment valve 468 and an on/off control valve 469, allowing the substrate processing liquid to be supplied to nozzle 53 at an appropriate flow rate and with appropriate timing.

Returning to Figure 5, the explanation continues. The DIW supply control unit 62 has a DIW supply pipe 621 connected to the nozzle 53, and a valve 652 that opens and closes the DIW supply pipe 651. The DIW supply pipe 651 is connected to a DIW supply source. When the valve 622 is opened in response to an open/close command from the control unit 4, DIW is supplied to the nozzle 53 as a rinsing liquid and discharged from the discharge port 53a toward the center of the surface of the substrate W.

The gas supply control unit 63 has a gas supply pipe 651 connected to the nozzle 53 and a valve 652 that opens and closes the gas supply pipe 651. The gas supply pipe 651 is connected to a gas supply source. In this embodiment, dehumidified nitrogen gas is used as the gas. When the valve 652 is opened in response to an opening/closing command from the control unit 4, the nitrogen gas is supplied to the nozzle 53 and sprayed from the outlet 53a toward the center of the surface of the substrate W. Note that, in addition to nitrogen gas, an inert gas such as dehumidified argon gas may also be used as the gas.

In the processing unit 1, an exhaust tub 80 is provided to surround the spin chuck 3. Also provided are a plurality of cups 81, 82 (first cup 81 and second cup 82) arranged between the spin chuck 3 and the exhaust tub 80, and a plurality of guards 84-86 (first guard 84 to third guard 86) that catch processing liquid splashed around the substrate W. Guard lifting/lowering drive mechanisms 87-89 (first to third guard lifting/lowering drive mechanisms 87-89) are connected to the guards 84-86, respectively. The guard lifting/lowering drive mechanisms 87-89 independently raise and lower the guards 84-86 in response to lifting/lowering commands from the control unit 4. The first guard lifting/lowering drive mechanism 87 is not shown in Figure 5.

The control unit 4 has an arithmetic unit such as a CPU, a storage unit such as a fixed memory device or a hard disk drive, and an input/output unit. The storage unit stores a program executed by the arithmetic unit. The control unit 4 controls each part of the device in accordance with the program, thereby performing the substrate processing shown in Figure 9 using a substrate processing solution that contains not only an etchant but also a migration promoter.

Figure 8 shows the contents of the substrate processing performed by the substrate processing apparatus of Figure 3. The processing object in the substrate processing apparatus 100 is a substrate W for manufacturing FinFETs, for example, as shown in the upper drawing of Figure 1, and on this substrate W, a TiN layer 12a for the HKMG layer is formed across multiple fins F.

Before an unprocessed substrate W is loaded into the processing unit 1, the control unit 4 issues commands to each component of the apparatus, and the processing unit 1 is set to its initial state. That is, the shutter 23 (Figures 4 and 5) is closed by the shutter opening/closing mechanism 22. The spin chuck 3 is positioned and stopped at a position suitable for loading the substrate W by the substrate rotation drive mechanism 34, and the chuck pins 31 are opened by a chuck opening/closing mechanism (not shown). The shielding plate 51 is positioned at a retracted position by the shielding plate lifting/lowering drive mechanism 56, and rotation of the shielding plate 51 by the shielding plate rotation drive mechanism 55 is stopped. All of the guards 84-86 have been moved downward and are positioned accordingly. Furthermore, all of the valves 612, 622, and 632 are closed.

When an unprocessed substrate W is transported by the substrate transport robot 111, the shutter 23 opens. As the shutter 23 opens, the substrate W is transported into the internal space 21 of the chamber 2 by the substrate transport robot 111 and transferred to the spin chuck 3 with its front surface Wf facing upward. The chuck pins 31 then close, and the substrate W is held by the spin chuck 3 (Step S1: Substrate Transport).

Following the loading of the substrate W, the substrate transport robot 111 retreats to the outside of the chamber 2, and the shutter 23 closes again. Then, the control unit 4 controls the motor of the substrate rotation drive mechanism 34 to increase the rotational speed (number of rotations) of the spin chuck 3 to a predetermined processing speed (within a range of approximately 10 to 3000 rpm, for example, 800 to 1200 rpm) and maintain that processing speed. The control unit 4 also controls the shield plate lift drive mechanism 56 to lower the shield plate 51 from its retreated position to the shielding position (step S2). The control unit 4 also controls the guard lift drive mechanisms 87 to 89 to raise the first guard 84 to the third guard 86 to their upper positions, thereby positioning the first guard 84 opposite the peripheral edge of the substrate W.

When the rotation of the substrate W reaches the processing speed, the control unit 4 then opens the valve 622. This causes DIW to be discharged from the outlet 53a of the nozzle 53 and supplied to the surface Wf of the substrate W. On the surface Wf of the substrate W, the DIW is subjected to centrifugal force due to the rotation of the substrate W and moves to the peripheral edge of the substrate W. This results in the entire surface Wf of the substrate W being covered with DIW, a so-called cover rinse process (step S3). Note that the cover rinse is not an essential step, and it is also possible to immediately perform the etching process (step S4), which will be described next, without performing the cover rinse.

In step S4, the control unit 4 closes valve 612 and opens valve 622. As a result, the liquid ejected from the outlet 53a of the nozzle 53 changes from DIW to substrate processing liquid, and the substrate processing liquid is supplied to the surface Wf of the substrate W. On the surface Wf of the substrate W, the substrate processing liquid is subjected to centrifugal force caused by the rotation of the substrate W and moves to the peripheral edge of the substrate W. As a result, the entire surface Wf of the substrate W is etched with the substrate processing liquid. At this time, the substrate processing liquid contains hydrochloric acid (or hydrochloric acid + ammonium chloride) as a complexing agent, in addition to an etchant for the TiN layer 12a. Moreover, the pH of the substrate processing liquid is adjusted to approximately 2.

The etching process using this substrate processing liquid continues for a predetermined etching time, during which time the substrate processing liquid discharged from the peripheral edge of the substrate W is received on the inner wall of the first guard 84 and sent to waste liquid processing equipment outside the machine along a drainage path (not shown). Once the etching time has elapsed, the control unit 4 closes the valve 612 to stop the discharge of the substrate processing liquid from the nozzle 53.

Following the etching process, a rinse process using a rinse liquid (DIW) is performed (step S5). During this DIW rinse, the control unit 4 opens the valve 622 while maintaining the positions of the first guard 84 to the third guard 86. As a result, DIW is supplied as rinse liquid from the outlet 53a of the nozzle 53 to the center of the surface Wf of the substrate W that has been subjected to the etching process. The DIW then moves to the periphery of the substrate W due to centrifugal force caused by the rotation of the substrate W. This washes away the substrate processing liquid adhering to the substrate W, thereby stopping etching with the substrate processing liquid. At this time, the DIW discharged from the periphery of the substrate W is discharged from the periphery of the substrate W to the side of the substrate W and, like the substrate processing liquid, is sent to waste liquid treatment equipment outside the apparatus. This DIW rinse continues for a predetermined rinse time, after which the control unit 4 closes the valve 622 to stop the discharge of DIW from the nozzle 53.

After the DIW rinse is complete, the control unit 4 increases the rotation speed of the substrate W to perform spin drying (step S6). In this embodiment, in parallel with the spin drying, the control unit 4 opens the valve 632 to spray dry nitrogen gas from the nozzle 53 onto the surface Wf of the substrate W during spin drying. This promotes drying of the substrate W.

After continuing spin drying for a predetermined time, the control unit 4 controls the motor of the substrate rotation drive mechanism 34 to stop the rotation of the spin chuck 3 and closes the valve 632 to stop the spray of nitrogen gas (step S7). The control unit 4 also controls the shield plate rotation drive mechanism 55 to stop the rotation of the shield plate 51 and controls the shield plate lift drive mechanism 56 to lift the shield plate 51 from the shielding position and position it in the retracted position. The control unit 4 also controls the third guard lift drive mechanism 89 to lower the third guard 86, retracting all guards 86-88 downward from the peripheral edge surface of the substrate W.

Then, the control unit 4 controls the shutter opening/closing mechanism 22 to open the shutter 23 (Figures 3 and 5), and the substrate transport robot 111 enters the internal space of the chamber 2 and unloads the processed substrate W, which has been released from the chuck pins 31, from the chamber 2 (step S8). Once the substrate W has been unloaded and the substrate transport robot 111 has moved away from the processing unit 1, the control unit 4 controls the shutter opening/closing mechanism 22 to close the shutter 23.

As described above, in this embodiment, the etching process (step S4) is performed on the TiN layer 12a using a substrate processing solution. This allows the etchant to efficiently penetrate into the interior of the trench structure, i.e., into the narrow space 12f. As a result, the TiN layer 12a (the layer to be etched) that forms the bottom wall 12d and sidewall 12e is etched at an excellent etching rate. The exposed areas of the TiN layer 12a are also effectively etched by the substrate processing solution. As a result, a metal layer 12 having the desired shape and thickness can be formed, as shown in the lower part of Figure 1.

As described above, in this embodiment, Ti and TiN correspond to examples of the "metal" and "metal compound" of the present invention, respectively. Furthermore, the HKMG layer 13 and TiN layer 12a correspond to examples of the "high-k metal gate layer" and "surface layer of the high-k metal gate layer" of the present invention, respectively. Furthermore, the opening dimension OW of the TiN layer 12a corresponds to the "narrow space width" of the present invention.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above are possible without departing from the spirit of the present invention. For example, the method of supplying the additional complexing agent may be changed. For example, an aqueous ammonium chloride solution may be prepared by dissolving ammonium chloride in a small amount of DIW in advance, and this may then be sent to tank 461 for mixing.

In addition, in the above embodiment, the substrate processing liquid is generated immediately before being supplied to the substrate W and then supplied to the substrate W from the nozzle 53 for etching processing, but the substrate processing liquid may also be configured to pass through a heating section before being supplied to adjust the temperature to a temperature suitable for etching processing.

In addition, in the above embodiment, the present invention is applied to a so-called single-wafer type substrate processing apparatus 100 that supplies a substrate processing liquid to a substrate W held on a spin chuck 3 to perform an etching process, but the present invention may also be applied to so-called batch type substrate processing apparatuses. In other words, etching may be performed by immersing a substrate holder holding multiple substrates W in the substrate processing liquid stored in a processing tank.

In addition, the above embodiments use a substrate processing solution that is a 0.1:1:5 mixture of hydrochloric acid (complexing agent), an aqueous hydrogen peroxide solution containing an etchant (chemical solution), and DIW, or a substrate processing solution to which ammonium chloride is added as an additional complexing agent. In other words, a substrate processing solution with a pH of approximately "2" is used, but a substrate processing solution with a pH adjusted to between 1 and 6 by controlling the mixing ratio of hydrochloric acid may also be used. For example, a substrate processing solution with a pH adjusted to "3" is "Example 1" described later, and a substrate processing solution with a pH adjusted to "1" is "Example 3" and "Example 5" described later.

In addition, instead of supplying the substrate processing liquid to the substrate W, the liquid components that make up the substrate processing liquid may be supplied directly to the substrate W to perform the etching process. For example, a mixed liquid (= chemical liquid + DIW) and hydrochloric acid (complexing agent) may be supplied directly to the substrate W to perform the etching process. Alternatively, a mixed liquid (= hydrochloric acid + chemical liquid + DIW) and ammonium chloride (additional complexing agent) may be supplied directly to the substrate W to perform the etching process.

In addition, in the above embodiment, a TiN layer is etched as an example of the "layer to be etched" in the present invention, but the present invention can also be applied to substrate processing techniques and substrate processing solutions for etching other metal layers (MG) used in the gate of a FinFET.

In the above embodiment, the substrate W to be processed is a substrate in which the bottom wall 12d and two sidewalls 12e constituting the trench structure, as shown in FIG. 1, are layers to be etched. However, the application of the present invention is not limited to this. For example, the present invention can be applied to a substrate in which one of the two sidewalls 12e and the bottom wall 12d are layers to be etched. The present invention can also be applied to a substrate in which the sidewall 12e is a cylindrically shaped layer to be etched. Furthermore, the present invention can be applied to a substrate in which only the bottom wall 12d is a layer to be etched. For example, as explained in the following example, the present invention also applies to a substrate processing technology for etching a substrate having a stacked structure in which a thin metal layer or metal compound layer is sandwiched between layers of different compositions (such as a silicon layer or a silicon oxide layer). Substrates having such a stacked structure and requiring etching of a thin metal layer or metal compound layer include, for example, substrates used to manufacture 3D-NAND memory.

Furthermore, the composition of the substrate processing solution is not limited to the above, and the first complex-forming agent and second complex-forming agent described in the "Summary of the Invention" section above can also be used. Specific examples and effects of these agents will be described in detail in the following examples.

Preferred embodiments of the present invention will now be described in more detail with reference to examples. However, the present invention is not limited to the examples below. Therefore, it is of course possible to make appropriate modifications within the scope of the spirit described above, and all such modifications are within the technical scope of the present invention.

Here, to evaluate the etching rate in narrow and non-narrow spaces, we prepared the sample shown in Figure 9 and conducted the following experiment.

Figure 9 is a schematic diagram showing the structure and experimental details of a sample used to evaluate the etching rate. In the substrate Wa shown in column (a) of the figure, a TiN layer W2 is formed on the upper surface of a silicon substrate W1. Furthermore, a polysilicon layer W3 is laminated on the TiN layer W2. This polysilicon layer W3 has a plurality of through-holes W4, each with an inner diameter of 60 nm. When a substrate processing solution containing the etchant is supplied to the surface of the substrate Wa configured in this manner, the substrate processing solution is supplied to the TiN layer W2 through the through-holes W4. The etchant contained in the substrate processing solution etches the exposed region W5 of the TiN layer W2 facing the through-holes W4. Over time, the etchant penetrates through the opening W6 (i.e., the gap between the silicon substrate W1 and the polysilicon layer W3) into the narrow space W7 between the silicon substrate W1 and the polysilicon layer W3. This progresses the etching of the narrow space W7.

When the size of the opening W6 (corresponding to the thickness THa of the TiN layer W2) is relatively large, as shown in (b) of the same figure, an etching rate can be obtained that is approximately the same as when the substrate processing solution is supplied to a substrate Wb on which a blanket-like TiN layer W2, for example, with a thickness of about 500 nm, is formed on the upper surface of the silicon substrate W1. For example, if the etching amounts EMa and EMb are the amounts etched from the supply of the chemical solution to the substrates Wa and Wb until a certain time has elapsed, respectively,
EMa ≒ EMb
If (EMa/EMb) is defined as the blanket ratio of the substrate Wa, then as the thickness THa of the TiN layer W5 in the substrate Wa becomes thinner, it becomes more difficult for the etchant to enter the narrow space W7, as in the case where the opening dimension OW in the upper part of FIG. 1 becomes narrower. Therefore, the etching rate becomes smaller, and the blanket ratio of the substrate Wa decreases from "1". Therefore, in this example, substrates Wa and Wb having THa of 2 nm, 5 nm, and 10 nm were prepared, and seven types of substrate processing solutions were prepared.

These substrate processing solutions are as shown in Table 1: (1) a mixture of hydrochloric acid, aqueous hydrogen peroxide, and DIW in a ratio of 1:1:5 (pH less than 1); (2) a mixture of aqueous hydrogen peroxide and DIW in a ratio of 1:5 (pH approximately 5);
(3) A mixture of hydrochloric acid, aqueous hydrogen peroxide, and DIW in a ratio of 0.001:1:5 (pH approximately 3).
(4) A mixture of hydrochloric acid, aqueous hydrogen peroxide, and DIW in a ratio of 0.01:1:5 (pH approximately 2).
(5) A mixture of hydrochloric acid, aqueous hydrogen peroxide, and DIW in a ratio of 0.1:1:5 (pH approximately 1)
(6) A mixture of hydrochloric acid, aqueous hydrogen peroxide, and DIW in a ratio of 0.01:1:5 (corresponding to the substrate processing solution (4) above) to which 1 mM of ammonium chloride was added as an additional complexing agent (pH approximately 2).
(7) A mixture of hydrochloric acid, an aqueous hydrogen peroxide solution, and DIW in a ratio of 0.1:1:5 (corresponding to the substrate treatment solution (5)) to which 1 mM of ammonium chloride was added as an additional complexing agent (pH of approximately 1);
is.

Each substrate processing solution was supplied to substrates Wa and Wb, and the etching depth per minute, i.e., the etching amounts EMca and EMb, were measured to determine the etching rate (ER (nm/min)) in the narrow space W7. Furthermore, (EMa/EMb) is the blanket ratio (BL ratio) for substrate Wa. Table 1 summarizes these results. Furthermore, for substrate processing solutions (1) to (5) containing no additional complexing agent, the blanket ratio is plotted against the thickness THa corresponding to the opening dimension OW of the TiN layer 12a shown in FIG. 1 (Comparative Examples 1 and 2, Examples 1 to 3). Furthermore, to verify the effect of adding an additional complexing agent, the blanket ratio is plotted against the thickness THa corresponding to the opening dimension OW of the TiN layer 12a shown in FIG. 1 for substrate processing solutions (4) to (7) (Examples 2 to 5).

As is clear from Table 1 and Figure 10, when etching was performed using substrate processing solution (2) that did not contain hydrochloric acid (first complexing agent), the etching rate in the narrow space W7, particularly at 2 nm, was low (Comparative Example 2). Furthermore, when etching was performed using substrate processing solution (1) that contained hydrochloric acid (first complexing agent) but had a pH of less than 1, the etching rate in the narrow space W7 was low (Comparative Example 1). In contrast, when etching was performed using substrate processing solutions (3) to (5) that contained hydrochloric acid (first complexing agent) and had a pH of 1 or greater, the etching rate in the narrow space W7 was significantly improved compared to Comparative Examples 1 and 2 (Examples 1 to 3). Thus, by using substrate processing solutions (3) to (5), the etchant efficiently penetrated the narrow space W7, enabling the TiN layer W2 facing the narrow space W7 to be etched at an excellent etching rate and blanket ratio. Furthermore, the greatest improvement was observed when etching was performed using substrate processing solution (2) with a pH of approximately 2. In other words, with a substrate processing solution made by mixing hydrochloric acid, aqueous hydrogen peroxide, and DIW, adjusting the pH to between 1 and 6 can improve etching performance in narrow spaces, but this effect is pH-dependent, so it is best to adjust the pH to around 2.

Furthermore, as is clear from Table 1 and Figure 11, the addition of an additional complexing agent can improve the etching rate and blanket ratio. However, this effect also depends on the pH, and it is preferable to adjust the pH to around 2.

This invention can be applied to substrate processing solutions for etching substrates having trench structures, as well as to general substrate processing in which substrates are processed using such substrate processing solutions.

1... Processing unit (substrate processing apparatus)
3...Spin chuck (substrate holder)
11... high-k dielectric layer 12... metal layer 12a... TiN layer (surface layer of high-k metal gate layer)
12c... Opening 12d... Bottom wall 12e... Side wall 12f... Narrow space 13... HKMG layer (high-k metal gate layer)
400... Processing liquid supply section F... Fin OW... Opening dimension (narrow space width)
W, Wa, Wb...substrate

Claims (11)

1. A substrate processing solution for removing a layer to be etched by being supplied to a substrate having a trench structure, the substrate having a narrow space formed by an opening having a narrow width, a bottom wall opposing the opening, and one or more side walls extending from the bottom wall toward the opening, and at least one of the bottom wall and the side wall being formed of a layer to be etched that is made of a metal or a compound of the metal,
a chemical solution containing H ₂ O ₂ molecules or HO ₂ ⁻ that functions as an etchant for etching the metal;
a first complexing agent containing an anion that forms a complex with an ion of the metal;
A substrate processing solution adjusted to a pH of 1 or more and a pH of 3 or less. The substrate processing solution according to claim 1 ,
A high-k metal gate layer is formed on the substrate to straddle and cover two adjacent fins that are spaced apart from each other and stand upright on the surface of the substrate to form a gate of a FinFET;
A substrate processing solution that etches and removes a surface layer of the high-k metal gate layer as the etching target layer. The substrate processing solution according to claim 2,
The substrate processing solution, wherein the metal contains at least one of titanium and tantalum. The substrate processing solution according to claim 1 ,
The chemical solution is a substrate processing solution that is an aqueous hydrogen peroxide solution. The substrate processing solution according to claim 1 ,
The substrate processing solution wherein the anions are halogen ions. The substrate processing solution according to claim 5,
The substrate processing solution wherein the halogen ions are chloride ions. The substrate processing solution according to claim 6,
The substrate processing solution wherein the first complex-forming agent is hydrochloric acid. The substrate processing solution according to claim 1 ,
The substrate processing solution further comprises a second complexing agent comprising NH ₄ ⁺ that forms a complex with ions of the metal. The substrate processing solution according to claim 1 ,
The narrow width of the substrate processing liquid is 2 nm or more and 10 nm or less. a step of supplying a substrate processing solution to a substrate having a trench structure in which a narrow space is formed by an opening having a narrow width, a bottom wall facing the opening, and one or more side walls extending from the bottom wall toward the opening, and at least one of the bottom wall and the side wall is formed by an etching layer made of a metal or a compound of the metal, to start removing the etching layer;
removing the substrate processing solution from the substrate to stop removal of the layer to be etched;
The substrate processing solution is
a chemical solution containing H ₂ O ₂ molecules or HO ₂ ⁻ that functions as an etchant for etching the metal;
a first complexing agent containing an anion that forms a complex with an ion of the metal;
A substrate processing method, characterized in that the pH is adjusted to 1 or more and 3 or less. a substrate holding part for holding a substrate having a trench structure in which a narrow space is formed by an opening having a narrow width, a bottom wall facing the opening, and one or more side walls extending from the bottom wall toward the opening, and at least one of the bottom wall and the side wall is formed by an etching layer composed of a metal or a compound of the metal;
a processing liquid supply unit that supplies a substrate processing liquid to the substrate held by the substrate holder,
The substrate processing solution is
a chemical solution containing H ₂ O ₂ molecules or HO ₂ ⁻ that functions as an etchant for etching the metal;
a first complexing agent containing an anion that forms a complex with an ion of the metal;
A substrate processing apparatus characterized in that the pH is adjusted to 1 or more and 3 or less.