Substrate processing solution, substrate processing method, and substrate processing apparatus

Abstract

To perform an etching process at an excellent etching rate on a substrate in which at least one of a bottom wall and a side wall forming a trench structure is a layer to be etched made of a metal or a compound of the metal.SOLUTION: A substrate processing liquid according to the present invention includes a chemical solution containing H2O2 molecules or HO2- that functions as an etchant to etch a metal, and a first complex-forming agent containing an anion that forms a complex with the metal ion, and is adjusted to pH 1 or higher and pH 6 or lower.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a substrate processing liquid for etching a substrate having a trench structure, a substrate processing method for processing a substrate with the substrate processing liquid, and a substrate processing apparatus. [Background technology]

[0002] 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 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. Patent Document 1 uses reactive ion etching (RIE) to pattern the HKMG layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2015-536581 (Paragraph 0016) Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the use of wet etching has been considered for the manufacture of electronic components such as the 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, it has become necessary to perform etching processes in narrow spaces. For example, to form a metal layer in a FinFET, as shown in FIG. 1 (described later), a TiN layer is formed on the fin using a material constituting the metal layer, such as TiN, and then the TiN layer is partially removed using an etching solution to achieve a desired shape. The TiN layer formed across multiple fins has a trench structure. Therefore, to achieve the desired shape, an etchant for etching the TiN layer must be introduced into the trench structure. However, as the fin pitch of a FinFET becomes narrower, the opening of the trench structure becomes narrower, resulting in a narrow space inside the trench structure. This makes it difficult to efficiently introduce the etchant, and the etching rate in the narrow space decreases. As a result, there has been a problem in that the metal layer cannot be finished into the desired shape. This problem is not limited to cases where the bottom wall constituting the 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.

[0005] The present invention has been made 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 are capable of performing an etching process at an excellent etching rate on a substrate in which at least one of the bottom wall and side wall forming a trench structure is an etched layer made of a metal or a compound of that metal. [Means for solving the problem]

[0006] A first aspect of the present invention is a substrate processing solution for removing a layer to be etched by supplying it 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 walls being formed of a layer to be etched that is a metal or a compound of the metal, the substrate processing solution comprising: H2O2 molecules or HO2 - and a first complex-forming agent containing an anion that forms a complex with the metal ion, 3 It is characterized by the following adjustments:

[0007] 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 at least one of the bottom wall and the side walls being formed by an etching layer made of a metal or a compound of the metal, to start removal of the etching layer; and removing the substrate processing liquid from the substrate to stop removal of the etching layer, wherein the substrate processing liquid is a liquid containing H2O2 molecules or HO2 - and a first complex-forming agent containing an anion that forms a complex with the metal ion, 3 It is characterized by the following adjustments:

[0008] A third aspect of the present invention is a substrate processing apparatus comprising: a substrate holding unit 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 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 walls is formed by an etching target layer made of a metal or a compound of the metal; and a processing liquid supply unit for supplying a substrate processing liquid to the substrate held by the substrate holding unit, wherein the substrate processing liquid is a mixture of H2O2 molecules or HO2 - and a first complex-forming agent containing an anion that forms a complex with the metal ion, 3 It is characterized by the following adjustments: [Effects of the Invention]

[0009] According to the invention thus configured, H2O2 molecules or HO2 which function as an etchant for etching metals - and a first complex-forming agent containing an anion that forms a complex with a metal ion, 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 forming the trench structure is an etched layer made of a metal or a compound of the metal. [Brief explanation of the drawings]

[0010] [Figure 1] 1A to 1C are diagrams schematically illustrating an embodiment of a substrate processing method according to the present invention. [Figure 2] 1 is a graph showing the change in zeta potential of Si, PSL, Si3N4, and SiO2 with respect to pH. [Figure 3] 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. [Figure 4] FIG. 4 is a side view of the substrate processing apparatus shown in FIG. [Figure 5] FIG. 2 is a partial cross-sectional view showing the configuration of a processing unit. [Figure 6] FIG. 2 is a block diagram showing the electrical configuration of a control unit that controls the processing unit. [Figure 7] FIG. 2 is a diagram showing a configuration of a substrate processing liquid supply unit. [Figure 8] 4 is a diagram showing the contents of substrate processing performed in the substrate processing apparatus of FIG. 3. FIG. [Figure 9] 1A and 1B are diagrams schematically illustrating the configuration of a sample for evaluating an etching rate and the details of an experiment. [Figure 10] 1 is a graph showing the etching characteristics of substrate processing solutions (1) to (5). [Figure 11] 10 is a graph showing the etching characteristics of substrate processing solutions (4) to (7). DETAILED DESCRIPTION OF THE INVENTION

[0011] <Summary of the Invention> The present invention relates to a substrate processing method and a substrate processing apparatus for wet-etching at least one of the bottom wall and side wall of a trench structure formed in a substrate, the layer to be etched being formed into a desired shape by supplying a substrate processing solution to the substrate, and a substrate processing solution for effectively performing the etching. In particular, in the substrate processing method according to the present invention, the layer to be etched is made of a metal or a metal compound, and H2O2 molecules or HO2 - The etching process is performed using a chemical solution containing the compound. For example, a hydrogen peroxide solution (Comparative Example 2, which will be described later) can be used as the chemical solution. The substrate processing method corresponds to one step in manufacturing a gate of a FinFET, as shown in FIG. 1.

[0012] FIG. 1 is a diagram schematically 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 made of TiN, TaN, TaAlN, TiC, or the like is stacked to a desired thickness on a high-k dielectric layer 11 formed across multiple fins F extending upward from a substrate W made of silicon or the like (see the bottom drawing (b) of FIG. 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.

[0013] Here, the metal layer 12 is formed in two stages. That is, as shown in the upper diagram (a) of Fig. 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 the 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 having the desired thickness, as shown in the lower diagram (b) of the same figure.

[0014] It should be noted here that the TiN layer 12a is formed along 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 a narrow width. The bottom wall 12d and sidewall 12e forming 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 constituting the bottom wall 12d and sidewall 12e of the trench structure is unavoidable. In this specification, the "narrow width" means 2 nm or more and 10 nm or less.

[0015] Therefore, the inventors of the present application 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 a complex in the narrow space 12f, in other words, promoting the dissolution of the layer to be etched. Based on this finding, the inventors of the present application have found that adding a complex-forming agent containing complex-forming ions to the substrate processing solution is effective in promoting the formation of a complex in the narrow space 12f, in other words, promoting the dissolution of the layer to be etched. + We have invented a substrate processing solution using as a complex-forming ion.

[0016] On the other hand, the complex forming ions are NH4 + Besides, Cl - Halogen ions such as these are also considered as candidates, 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 SiO2, as shown in Figure 9, which will be explained later, the potential of the wall surface is greatly affected by pH.

[0017] Figure 2 is a graph showing the change in zeta potential of Si, PSL, Si3N4, and SiO2 versus pH. The source of this graph is T. Hattori: Ultraclean Surface Processing of Silicon Wafers, 119 (1998), where "Si" stands for silicon, "PSL" for polystyrene latex, "Si3N4" for silicon nitride, and "SiO2" for silicon dioxide. As is clear from this 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 impediment of etchant ion penetration due to the electric double layer. In contrast, in the acidic range of pH 6 or less, the zeta potential of Si, SiO2, etc. rises, and the narrow interface also becomes positively charged or approaches a positive charge. Therefore, HO 2- It is believed that this facilitates the penetration of 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 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 this effect is negated by the decrease in the concentration of etchant ions. 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.

[0018] A mixed solution (Comparative Example 2 to be described later) in which an aqueous hydrogen peroxide solution and DIW (deionized water) are mixed at a ratio of 1:5 has a pH of about 5. When hydrochloric acid (HCl) is added to this as the first complex-forming agent of the present invention, Cl is released from the substrate processing solution. - The pH of the substrate processing solution further decreases as the hydrochloric acid content (complex-forming ions) increases. However, if the mixing ratio of hydrochloric acid, aqueous hydrogen peroxide solution, and DIW in the substrate processing solution becomes 1:1:5, the pH of the substrate processing solution (Comparative Example 1 described later) will fall below 1. Therefore, it is desirable to adjust the mixing ratio of hydrochloric acid in the substrate processing solution to 0.1 or less, and more preferably in the range of 0.001 to 0.1 (Examples 1 to 3 described later). Furthermore, these effects are due to the addition of Cl. -Alternatively, the effect can be achieved by using a first complex-forming agent containing an anion that forms a complex with a metal ion (Ti in this embodiment), such as a halogen ion.

[0019] As described above, in manufacturing the HKMG layer 13 of the FinFET, the substrate processing solution for etching the TiN layer 12a that forms the bottom wall 12d and the side wall 12e of the trench structure contains H2O2 molecules and HO2 - Although a chemical solution containing an etchant such as TiN or TiN may be used, 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 ion (Ti in this embodiment) 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., the narrow space 12f. Therefore, the TiN layer 12a (the layer to be etched) that forms the bottom wall 12d and the sidewall 12e can be etched at an excellent etching rate. As a result, a high-performance FinFET can be manufactured.

[0020] Also, as mentioned above, NH4 + can be used as a complexing ion, so a second complexing agent containing such a cation may be added. This second complexing agent may be the ammonium ion NH + The general formula (NH4 + ) n X n- where X n- is an n-valent anion, where 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 Acetate NH4CH3CO2 (Ammonium Acetate) Ammonium Phosphate (NH4)2PO4 (Ammonium Phosphate) Includes:

[0021] Alternatively, an alkylammonium salt can be used as the second complex-forming agent. The alkylammonium salt has the general formula (NR4 + ) n X n- quaternary ammonium salts represented by R3N, tertiary 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 (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.

[0022] By adding the second complex-forming agent as needed, complex formation in a narrow space is promoted, and dissolution of the material to be etched is promoted. Note that, in the following, the second complex-forming agent containing a cation, which is added as needed, will be referred to as an "additional complex-forming agent" to distinguish it from the first complex-forming agent, such as hydrochloric acid, which is always used.

[0023] <Substrate processing equipment> Next, the configuration and operation of a substrate processing apparatus that performs the substrate processing method shown in FIG. 1 using the substrate processing solution will be described with reference to FIGS.

[0024] FIG. 3 is a diagram showing a first embodiment of a substrate processing apparatus capable of performing the substrate processing method shown in FIG. 1. FIG. 4 is a side view of the substrate processing apparatus shown in FIG. 3. This substrate processing apparatus 100 is an apparatus that performs an etching process on a substrate W shown in the upper part of FIG. 1 using the substrate processing liquid. 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 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 a substrate W for manufacturing a FinFET to form a metal layer (reference numeral 12 in FIG. 1) of an HKMG layer.

[0025] In this embodiment, to form metal layer 12 by etching TiN layer 12a in the upper drawing of FIG. 1, a substrate processing solution prepared by mixing hydrochloric acid, which functions as a complexing agent, a hydrogen peroxide aqueous 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.

[0026] 3, the substrate processing apparatus 100 includes 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 includes a container holder 121 that can hold a plurality of containers C for accommodating substrates W (such as a FOUP (Front Opening Unified Pod), an SMIF (Standard Mechanical Interface) pod, or an OC (Open Cassette) that accommodates 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 or store processed substrates W in the container C. Each container C accommodates a plurality of substrates W in a substantially horizontal position.

[0027] The indexer robot 122 comprises a base 122a fixed to the apparatus 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 its upper surface and held thereon. Indexer robots having such articulated arms and hands for holding substrates are well known, and therefore a detailed description thereof will be omitted.

[0028] The substrate processing section 110 includes a substrate transfer robot 111 disposed approximately in the center in a plan view, and a plurality of processing units 1 disposed to surround the substrate transfer robot 111. Specifically, a plurality of processing units 1 (eight in this example) are disposed facing the space in which the substrate transfer robot 111 is disposed. 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 function. This enables parallel processing of multiple substrates W.

[0029] Fig. 5 is a partial cross-sectional view showing the configuration of a processing unit. Fig. 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 be controlled by one control unit. Alternatively, the processing units 1 may be controlled by a control unit (not shown) that controls the entire substrate processing apparatus 100.

[0030] 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 a side surface 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. That is, the substrate W is placed on the spin chuck 3 with the TiN layer 12a (FIG. 1) facing upward. After the substrate W 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 performed 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. In this specification, "room temperature" means a temperature range of 5°C to 35°C.

[0031] The spin chuck 3 includes a plurality of chuck pins 31 for gripping the substrate W, a spin base 32 formed in a disk shape extending horizontally 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, the substrate processing liquid, DIW, and nitrogen gas are sequentially supplied onto the front surface Wf of the substrate W from nozzles provided in the atmosphere blocking mechanism 5 in response to a supply command from the control unit 4.

[0032] The atmosphere shutoff mechanism 5 includes a shutoff plate 51, an upper spin shaft 52 rotatably mounted on the shutoff plate 51, and a nozzle 53 vertically penetrating the center of the shutoff plate 51. The shutoff plate 51 is finished in a circular disk shape with a diameter substantially equal to or greater than that of the substrate W. The shutoff plate 51 is disposed opposite, with a gap therebetween, 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.

[0033] The upper spin shaft 52 is rotatably provided 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 peripheral 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.

[0034] The nozzle 53 is disposed 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, the upper spin shaft 52, and the support arm 54. A discharge port 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.

[0035] A shielding plate rotation drive mechanism 55 (FIG. 6) including an electric motor and the like 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 relative to the support arm 54 about the rotation axis C1 in response to a rotation command from the control unit 4. A shielding plate lift drive mechanism 56 is coupled to the support arm 54. The shielding plate lift drive mechanism 56 lifts and lowers the shielding plate 51, the upper spin shaft 52, and the nozzle 53 integrally 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 lifts and lowers the shielding plate 51, the upper spin shaft 52, and the nozzle 53 together with the support arm 54 between a blocking position (position shown in FIG. 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) where the substrate facing surface 51a is retracted significantly above the blocking position.

[0036] A processing liquid supply control unit 61, a DIW supply control unit 62, and a gas supply control unit 63 are connected to the upper end of the nozzle 53.

[0037] 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 the substrate processing liquid.

[0038] FIG. 7 illustrates the configuration of the substrate processing solution supply unit. The processing solution supply unit 400 includes a chemical solution supply system 410 that supplies an aqueous hydrogen peroxide solution (chemical solution) containing an etchant, 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 solution supply system 410 temporarily stores the aqueous hydrogen peroxide solution supplied from a hydrogen peroxide solution supply source in a tank 411 and supplies it to a mixing valve 450 at an appropriate timing. The chemical solution supply system 410 includes a pipe 412 that connects the tank 411 to a nitrogen gas supply source. A flow rate control valve 413 and an on / off control valve 414 are installed in the pipe 412. Therefore, by operating in response to commands from the control unit 4 (FIG. 6), nitrogen gas is pressure-fed to the tank 411 via the flow rate control valve 413 and the on / off control valve 414 at an appropriate flow rate. This allows the aqueous hydrogen peroxide solution stored in tank 411 to be supplied to mixing valve 450 via piping 415. In addition, flow rate adjustment valve 416 and on / off control valve 417 are installed in piping 415. Therefore, flow rate adjustment valve 416 and on / off control valve 417 operate in response to commands from control unit 4, thereby supplying the aqueous hydrogen peroxide solution to mixing valve 450 at an appropriate flow rate and at an appropriate timing. Meanwhile, in order to maintain the amount of aqueous hydrogen peroxide solution stored in tank 411 at a certain level or above, sensor 418 is provided for detecting 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 to tank 411 from the supply source.

[0039] The DIW supply system 420 has a pipe 421 connecting a DIW supply source and a 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 an appropriate timing.

[0040] The complexing agent supply system 430 has the function of temporarily storing hydrochloric acid in a tank 431 and supplying it to the mixing valve 450 at an appropriate timing. The complexing agent supply system 430 has a pipe 432 connecting the tank 431 with a hydrochloric acid supply source. A flow rate adjustment valve 433 and an on / off control valve 434 are installed in this pipe 432. In addition, a sensor 435 is provided to detect the liquid level of hydrochloric acid in the tank 431 in order to maintain the amount of hydrochloric acid stored in the tank 431 at a certain level or higher. The sensor 435 detects the liquid level, and based on the detection result, the flow rate adjustment valve 433 and the on / off control valve 434 are operated to replenish hydrochloric acid from the hydrochloric acid supply source to the tank 431.

[0041] 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 control unit 4, nitrogen gas is pressure-fed to tank 431 via flow rate adjustment valve 437 and on / off control valve 438 at an appropriate flow rate, and hydrochloric acid stored in tank 431 can be supplied to mixing valve 450 via piping 439. A flow rate adjustment valve 440 and on / off control valve 441 are installed in this piping 439. Therefore, by operating flow rate adjustment valve 440 and on / off control valve 441 in response to commands from control unit 4, hydrochloric acid is supplied to mixing valve 450 at an appropriate flow rate and at an appropriate timing.

[0042] Appropriate amounts of aqueous hydrogen peroxide solution, DIW, and hydrochloric acid are supplied to a mixing valve 450 and mixed therein. The mixed solution is then transferred to another tank 461 via a pipe 451. This tank 461 is connected to a supply source of an additional complexing agent (ammonium chloride in this embodiment) via a pipe 462. Thus, in response to a command from the control unit 4, the additional complexing agent is added from the supply source to the substrate processing solution stored in the tank 461, thereby generating 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 in the tank 461 to promote dissolution and mixing of the ammonium chloride by 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.

[0043] Tank 461 is also connected to a nitrogen gas supply source via pipe 464. Pipe 464 is also provided with a flow rate adjustment valve 465 and an on / off control valve 466. Therefore, by operating in response to a command 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 sent via pipe 467. Pipe 467 is also provided with a flow rate adjustment valve 468 and an on / off control valve 469, making it possible to supply the substrate processing liquid to nozzle 53 at an appropriate flow rate and at an appropriate timing.

[0044] 5, the explanation will be continued. 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 opening / closing command from the control unit 4, the 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.

[0045] 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, and 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, instead of nitrogen gas, an inert gas such as dehumidified argon gas may be used as the gas.

[0046] In the processing unit 1, an exhaust tub 80 is provided to surround the spin chuck 3. A plurality of cups 81, 82 (first cup 81 and second cup 82) are disposed between the spin chuck 3 and the exhaust tub 80, and a plurality of guards 84-86 (first guard 84 to third guard 86) are provided to receive 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 FIG. 5.

[0047] 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 apparatus in accordance with the program, thereby performing the substrate processing shown in FIG. 9 using a substrate processing solution containing not only an etchant but also a migration promoter.

[0048] Fig. 8 is a diagram showing the contents of substrate processing executed by the substrate processing apparatus of Fig. 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 Fig. 1, and on the substrate W, a TiN layer 12a for an HKMG layer is formed across multiple fins F.

[0049] 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 (FIGS. 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. The guards 84 to 86 are all moved downward and positioned. Furthermore, the valves 612, 622, and 632 are all closed.

[0050] When an unprocessed substrate W is transported by the substrate transport robot 111, the shutter 23 opens. In synchronization with the opening of the shutter 23, 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 the front surface Wf facing upward. Then, the chuck pins 31 are closed, and the substrate W is held by the spin chuck 3 (Step S1: Transporting the Substrate).

[0051] After the substrate W is loaded, the substrate transport robot 111 retreats to the outside of the chamber 2, and the shutter 23 closes again. Then, the controller 4 controls the motor of the substrate rotation drive mechanism 34 to increase the rotation 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 maintains the processing speed. The controller 4 also controls the shield plate lift drive mechanism 56 to lower the shield plate 51 from the retreated position to the shielding position (step S2). The controller 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.

[0052] When the rotation of the substrate W reaches the processing speed, the control unit 4 then opens the valve 622. As a result, DIW is discharged from the discharge port 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. As a result, the entire surface Wf of the substrate W is covered with DIW, a so-called cover rinse process is performed (step S3). Note that the cover rinse is not an essential step, and there is also a case where the etching process (step S4), which will be described next, is performed immediately without performing the cover rinse.

[0053] In step S4, the control unit 4 closes the valve 612 and opens the valve 622. As a result, the liquid discharged from the discharge port 53a of the nozzle 53 changes from DIW to the 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 due to 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 subjected to etching processing 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.

[0054] The etching process using this substrate processing liquid continues for a predetermined etching time, during which the substrate processing liquid discharged from the peripheral edge of the substrate W is received by the inner wall of the first guard 84 and sent to a waste liquid treatment facility outside the apparatus along a drainage path (not shown). When 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.

[0055] 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 a 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. As a result, the substrate processing liquid adhering to the substrate W is washed away by the DIW, and etching by the substrate processing liquid is stopped. 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 a waste liquid treatment facility outside the apparatus. This DIW rinse continues for a predetermined rinse time. After this time has elapsed, the control unit 4 closes the valve 622 to stop the discharge of DIW from the nozzle 53.

[0056] After the DIW rinse is completed, 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.

[0057] After the spin drying has continued 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 shielding plate rotation drive mechanism 55 to stop the rotation of the shielding plate 51 and controls the shielding plate lift drive mechanism 56 to lift the shielding plate 51 from the shielding position to position it at the retracted position. The control unit 4 also controls the third guard lift drive mechanism 89 to lower the third guard 86, thereby retracting all of the guards 86 to 88 downward from the peripheral edge surface of the substrate W.

[0058] Thereafter, the control unit 4 controls the shutter opening / closing mechanism 22 to open the shutter 23 (FIGS. 3 and 5), and then the substrate transfer robot 111 enters the internal space of the chamber 2 and transfers the processed substrate W, which has been released from the chuck pins 31, out of the chamber 2 (step S8). Note that, once the transfer of the substrate W is completed and the substrate transfer robot 111 moves away from the processing unit 1, the control unit 4 controls the shutter opening / closing mechanism 22 to close the shutter 23.

[0059] As described above, in this embodiment, the etching process (step S4) is performed on the TiN layer 12a using the substrate processing solution. Therefore, the etchant efficiently penetrates into the interior of the trench structure, i.e., the narrow space 12f. Therefore, the TiN layer 12a (the layer to be etched) constituting the bottom wall 12d and the side wall 12e is etched at an excellent etching rate. Furthermore, the exposed region of the TiN layer 12a is also well etched by the substrate processing solution. As a result, a metal layer 12 having a desired shape and thickness can be formed, as shown in the lower part of FIG. 1.

[0060] As described above, in this embodiment, Ti and TiN correspond to examples of the "metal" and "metal compound" of the present invention, respectively. 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. The opening dimension OW of the TiN layer 12a corresponds to the "narrowed portion width" of the present invention.

[0061] The present invention is not limited to the above-described embodiment, and various modifications can be made 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 ammonium chloride aqueous solution may be prepared by dissolving ammonium chloride in a small amount of DIW in advance, and this may be sent to tank 461 for mixing.

[0062] Furthermore, in the above embodiment, the substrate processing liquid is generated immediately before being supplied to the substrate W and is supplied from the nozzle 53 to the substrate W 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 level suitable for etching processing.

[0063] In the above embodiment, the present invention is applied to a so-called single-wafer type substrate processing apparatus 100 that performs etching processing by supplying a substrate processing liquid to a substrate W held on the spin chuck 3, but the present invention may also be applied to a so-called batch type substrate processing apparatus. That is, etching processing may be performed by immersing a substrate holder holding a plurality of substrates W in the substrate processing liquid stored in a processing tank.

[0064] Furthermore, in the above embodiment, a substrate processing solution is used in which hydrochloric acid (complexing agent), an aqueous hydrogen peroxide solution containing an etchant (chemical solution), and DIW are mixed in a ratio of 0.1:1:5, or to which ammonium chloride is added as an additional complexing agent. That is, although a substrate processing solution with a pH of approximately "2" is used, a substrate processing solution in which the pH is adjusted to between 1 and 6 by controlling the mixing ratio of hydrochloric acid may also be used. For example, a substrate processing solution adjusted to a pH of "3" is "Example 1" described later, and a substrate processing solution adjusted to a pH of "1" is "Example 3" and "Example 5" described later.

[0065] Furthermore, instead of supplying the substrate processing liquid to the substrate W, the etching process may be performed by directly supplying each of the liquid components constituting the substrate processing liquid to the substrate W. For example, the etching process may be performed by directly supplying each of the mixed liquid (= chemical liquid + DIW) and hydrochloric acid (complexing agent) to the substrate W. Alternatively, the etching process may be performed by directly supplying each of the mixed liquid (= hydrochloric acid + chemical liquid + DIW) and ammonium chloride (additional complexing agent) to the substrate W.

[0066] Furthermore, in the above embodiment, a TiN layer is etched as an example of the "etched layer" of 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.

[0067] In the above embodiment, the substrate W is processed as shown in FIG. 1 , in which the bottom wall 12d and two sidewalls 12e constituting the trench structure 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 described in the following example, the present invention also applies to a substrate processing technique 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 silicon layers or silicon oxide layers). 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.

[0068] The composition of the substrate processing solution is not limited to the above, and the first and second complex-forming agents described in the "Summary of the Invention" section above can be used. Specific examples and effects of these agents will be described in detail in the following examples. [Example]

[0069] Preferred embodiments of the present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples. Therefore, it is possible to carry out the present invention by making appropriate modifications within the scope of the above-mentioned gist, and all such modifications are included in the technical scope of the present invention.

[0070] Here, in order to evaluate the etching rate in the narrow space and the non-narrow space, the sample shown in FIG. 9 was prepared and the following experiment was carried out.

[0071] FIG. 9 is a diagram showing the structure of a sample used to evaluate the etching rate and the experimental results. 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 formed on the TiN layer W2. This polysilicon layer W3 has a plurality of through-holes W4, each with an inner diameter of, for example, 60 nm. When a substrate processing solution containing the etchant is supplied to the surface of the substrate Wa, 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 into the narrow space W7 between the silicon substrate W1 and the polysilicon layer W3 through the opening W6 (i.e., the gap between the silicon substrate W1 and the polysilicon layer W3). This progresses the etching of the narrow space W7.

[0072] 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 approximately the same as that obtained when etching is carried out by supplying a substrate processing solution 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 by the substrates Wa and Wb within a certain time after the chemical solution is supplied, 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 on the substrate Wa becomes thinner, it becomes more difficult for the etchant to penetrate into the narrow space W7, just as when 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 with THa of 2 nm, 5 nm, and 10 nm were prepared, and seven types of substrate processing solutions were prepared.

[0073] These substrate processing solutions are as shown in Table 1. (1) A mixture of hydrochloric acid, hydrogen peroxide solution, and DIW in a ratio of 1:1:5 (pH less than 1) (2) Aqueous hydrogen peroxide solution mixed with DIW in a ratio of 1:5 (pH is approximately 5) (3) A mixture of hydrochloric acid, hydrogen peroxide, and DIW in a ratio of 0.001:1:5 (pH approximately 3). (4) A mixture of hydrochloric acid, hydrogen peroxide, and DIW in a ratio of 0.01:1:5 (pH approximately 2). (5) A mixture of hydrochloric acid, hydrogen peroxide solution, 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 treatment solution (4) above) to which 1 mM ammonium chloride was added as an additional complexing agent (pH approximately 2). (7) A mixture of hydrochloric acid, aqueous hydrogen peroxide, and DIW in a ratio of 0.1:1:5 (corresponding to the substrate treatment solution (5) above) to which 1 mM ammonium chloride was added as an additional complexing agent (pH approximately 1); is.

[0074] Each substrate processing solution was supplied to substrates Wa and Wb, and the thickness etched 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) of substrate Wa. Table 1 summarizes these results. Furthermore, for substrate processing solutions (1) to (5) containing no additional complexing agent, the blanket ratios are plotted against the thickness THa corresponding to the opening dimension OW of 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 ratios are plotted against the thickness THa corresponding to the opening dimension OW of TiN layer 12a shown in FIG. 1 for substrate processing solutions (4) to (7) (Examples 2 to 5).

[0075] [Table 1]

[0076] As is clear from Table 1 and FIG. 10, when etching was performed using the 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 the 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 the substrate processing solutions (3) to (5) that contained hydrochloric acid (first complexing agent) and had a pH of 1 or higher, 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 the substrate processing solutions (3) to (5), the etchant was efficiently introduced into the narrow space W7, allowing the TiN layer W2 facing the narrow space W7 to be etched at an excellent etching rate and blanket ratio. Furthermore, the most significant improvement was observed when etching was performed using the substrate processing solution (2) with a pH of approximately 2. In other words, in a substrate processing solution made by mixing hydrochloric acid, aqueous hydrogen peroxide solution, and DIW, adjusting the pH to between 1 and 6 can improve etching performance in narrow spaces, but the effect is pH-dependent, and it is preferable to adjust the pH to around 2.

[0077] 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 about 2. [Industrial Applicability]

[0078] The present invention can be applied to a substrate processing solution for etching a substrate having a trench structure, and to general substrate processing in which a substrate is processed with the substrate processing solution. [Explanation of symbols]

[0079] 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 unit F...fin OW...Opening dimensions (narrow space width) W, Wa, Wb...substrate

Claims

1. 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, H, which acts as an etchant to etch the metal ２ O ２ molecule or HO ２ － A chemical solution containing a first complexing agent containing an anion that forms a complex with an ion of the metal; A substrate processing solution having a pH adjusted to 1 or more and 3 or less.

2. 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.

3. The substrate processing solution according to claim 2, The substrate processing solution, wherein the metal contains at least one of titanium and tantalum.

4. The substrate processing solution according to claim 1 , The chemical solution is a substrate processing solution that is an aqueous hydrogen peroxide solution.

5. The substrate processing solution according to claim 1 , The substrate processing solution, wherein the anions are halogen ions.

6. The substrate processing solution according to claim 5, The substrate processing solution wherein the halogen ions are chloride ions.

7. The substrate processing solution according to claim 6, The substrate processing solution wherein the first complex-forming agent is hydrochloric acid.

8. The substrate processing solution according to claim 1 , NH which forms a complex with the ions of the metal ４ ＋ The substrate treating solution further comprising a second complexing agent comprising:

9. 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.

10. 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 H, which acts as an etchant to etch the metal ２ O ２ molecule or HO ２ － A chemical solution containing a first complexing agent containing an anion that forms a complex with an ion of the metal; Adjusted to pH 1 or higher and pH 3 or lower A substrate processing method comprising:

11. 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 H, which acts as an etchant to etch the metal ２ O ２ molecule or HO ２ － A chemical solution containing a first complexing agent containing an anion that forms a complex with an ion of the metal; Adjusted to pH 1 or higher and pH 3 or lower A substrate processing apparatus comprising:

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