Film formation method

Abstract

This film formation method includes forming a pattern of a desired film containing a first element X1 on a substrate. The film formation method includes: forming an inhibition film containing boron on the substrate, which inhibits the formation of the desired film; forming a recess that penetrates the inhibition film at places of the inhibition film; using the remainder of the inhibition film to form a pattern of the desired film on the substrate; and removing the inhibition film that remains after forming the desired film. The first element X1 is a transition metal element, Al, Ga, In, or Sn. The formation of the desired film includes supplying, to the substrate, the following: a raw material gas containing the first element X1 and a halogen; and a reaction gas that reacts with the adsorbate of the raw material gas.

Description

Film forming method

[0001] The present disclosure relates to a film formation method.

[0002] Patent Document 1 describes a method for forming a pattern on a thin film made of a material that is difficult to etch.

[0003] Japanese Patent Application Publication No. 7-273280

[0004] One aspect of the present disclosure provides techniques for forming patterns of target films that include transition metal elements, Al, Ga, In, or Sn.

[0005] A film formation method according to one aspect of the present disclosure includes forming a pattern of a target film containing a first element X1 on a substrate. The film formation method includes forming an inhibitor film on the substrate, the inhibitor film containing boron and inhibiting the formation of the target film, forming a recess penetrating the inhibitor film in a portion of the inhibitor film, using the remaining portion of the inhibitor film to form a pattern of the target film on the substrate, and removing the inhibitor film remaining after the target film is formed. The first element X1 is a transition metal element, Al, Ga, In, or Sn. Forming the target film includes supplying to the substrate a source gas containing the first element X1 and a halogen, and a reactive gas that reacts with an adsorbate of the source gas.

[0006] According to one aspect of the present disclosure, a pattern of a target film containing a transition metal element, Al, Ga, In, or Sn can be formed.

[0007] FIG. 1 is a flowchart showing a film forming method according to an embodiment. FIG. 2 is a cross-sectional view showing the film forming method according to an embodiment. FIG. 3 is a cross-sectional view showing an example of processing performed in S102 of FIG. 2. FIG. 4 is a cross-sectional view showing an example of processing performed after S104 of FIG. 2. FIG. 5 is a cross-sectional view showing a film forming method according to a modified example. FIG. 6 is a cross-sectional view showing an example of processing performed after S104 of FIG. 5. FIG. 7 is a cross-sectional view showing a thin film pattern forming method according to a reference embodiment.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and their description may be omitted. In the specification, the symbol "to" indicating a range of values ​​means that the values ​​before and after the symbol "to" are included as the lower and upper limits. The range of values ​​includes the range rounded up or down.

[0009] A film formation method according to one embodiment will be described with reference to FIGS. 1 to 3. The film formation method includes forming a pattern of a target film 14 on a substrate 10, as shown in FIG. 2. The target film 14 includes a first element X1. The first element X1 is a transition metal element such as Al, Ga, In, or Sn. The transition metal element is a general term for elements found in groups 3 to 12. The target film 14 is, for example, an oxide film, a nitride film, or a metal film. The target film 14 may include a compound of the first element X1 and a nonmetal element X2. The nonmetal element X2 may be oxygen or nitrogen. The target film 14 is a so-called difficult-to-etch material. A hard-to-etch material is a material that contains a first element X1 with low halide volatility, making it more difficult to etch and forming an ideal vertical pattern for a device, compared to films that do not contain the first element X1, such as Si films, SiN films, SiO films, C films, B films, BN films, or BO films, which produce highly volatile halides as by-products upon etching. The finer the pattern, the more difficult it is to form a vertical pattern with a hard-to-etch material. When the target film 14 contains, for example, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Zn, Al, Ga, In, or Sn as the first element X1, it is more difficult to form a pattern thereon than with films that do not contain the first element X1, such as Si films, SiN films, SiO films, C films, B films, BN films, or BO films. Furthermore, when the target film 14 is composed of a compound containing two or more first elements X1, or when the target film 14 is composed of a compound of multiple elements including the first element X1, such as when the target film 14 is composed of a compound containing Si or Ge as the non-metallic element X2 in addition to the first element X1, it is difficult to form a pattern without altering the composition or film quality.

[0010] When the target film 14 is made of a hard-to-etch material containing the first element X1, it is difficult to form a pattern of the target film 14 by etching. For electrode and memory material applications, hard-to-etch materials containing the first element X1 are sometimes processed into fine patterns by thermal or plasma dry etching. However, the halide of the first element X1, which is a by-product of the etching reaction, is less volatile than the halides of Si, C, or B, making it difficult to process into a pattern. Even if etching is possible, it is difficult to form a fine, vertical pattern that is ideal for a device.

[0011] When dry etching a target film 14 made of a difficult-to-etch material containing a first element X1 using plasma, a halogen-containing gas is often used as the etching gas. The etching reaction involves halogenating the first element X1, which then becomes a metal halide of X1, which is then volatilized or sputtered away to form a pattern. However, many metal halides have low volatility and are difficult to remove from the substrate 10, hindering pattern formation. Metal halides can be removed by increasing the substrate temperature to promote volatilization or by strong sputtering using high-energy ions that fly from the plasma to the substrate 10. However, in both cases, the resulting pattern tends to have a tapered side profile, as shown in FIG. 7 .

[0012] Furthermore, when the target film 14 is composed of a compound containing two or more first elements X1, or a compound containing the first element X1 and a semiconductor element, the surface composition of the target film 14 may be altered when etching with a gas containing a halogen. Two or more first elements X1, or the first element X1 and a semiconductor element, each have different ease of removal by volatility or sputtering. Therefore, the surface composition or film quality of the difficult-to-etch material after etching may be altered from the composition or film quality before etching, potentially impairing the characteristics expected of the device.

[0013] Furthermore, when the target film 14 made of a difficult-to-etch material containing the first element X1 is dry-etched by plasma, ions are strongly bombarded onto the surface of the difficult-to-etch material, damaging the surface of the difficult-to-etch material and altering its composition or film quality. If the composition or film quality of the surface of the difficult-to-etch material changes from the composition or film quality before etching, it is thought that the characteristics expected of the device will be impaired.

[0014] Furthermore, the halide produced as a by-product after etching with the first element X1 has low volatility and is therefore not easily removed from the processing vessel after the reaction, and is likely to re-adhere to the substrate 10 or remain on the inner wall of the processing vessel or the inner wall of the exhaust piping. If the halide of the first element X1 re-adheres to the substrate 10, it may cause particles or etching defects. If the halide of the first element X1 remains on the inner wall of the processing vessel, it may peel off or be sputtered and adhere to the substrate 10, which may cause particles or etching defects. It may also shorten the cleaning cycle of the processing vessel and reduce productivity.

[0015] The film formation method of this embodiment includes, for example, steps S101 to S104 shown in Fig. 1. This allows for the formation of a pattern of the target film 14, as will be described in detail later. Note that the film formation method may include steps other than steps S101 to S104. For example, the film formation method may further include steps S105 to S107 shown in Fig. 4, which will be described later, or step S105 shown in Fig. 6, which will be described later.

[0016] Step S101 includes forming an inhibition film 11 on a substrate 10. The substrate 10 includes a semiconductor substrate. The semiconductor substrate is a silicon wafer or a compound semiconductor wafer. The compound semiconductor wafer is, for example, a GaAs wafer, a SiC wafer, a GaN wafer, or an InP wafer. The substrate 10 may include a film formed on a semiconductor substrate.

[0017] The inhibitor film 11 inhibits the formation of the target film 14 by containing boron (B). The B content in the inhibitor film 11 is, for example, 20 atomic % to 100 atomic %, and preferably 40 atomic % to 100 atomic %. The inhibitor film 11 is, for example, a B film, a BN film, a BNC film, a BO film, a BNOC film, a SiBN film, a SiBCN film, or a SiOBN film. Here, the BN film means a film containing boron (B) and nitrogen (N). The atomic ratio of B to N in the BN film is not limited to 1:1. Films other than BN films, such as BNC films, similarly contain each element and are not limited to a stoichiometric ratio.

[0018] Step S102 includes forming a recess 12 penetrating the inhibitor film 11 in a part of the inhibitor film 11. The depth of the recess 12 is approximately the same as the thickness of the inhibitor film 11 in FIG. 2, but as will be described later, it may be greater than the thickness of the inhibitor film 11, or a part of the substrate 10 may be removed. The substrate 10 is exposed inside the recess 12. Unlike the inhibitor film 11, the exposed part of the substrate 10 does not substantially contain B. "Substantially not containing B" means that the B content is 0 atomic % to 5 atomic %. The lower the B content, the better.

[0019] 3. Step S102a includes forming a resist film 13 on the inhibitor film 11. Note that one or more hard mask films (not shown) may be formed between the inhibitor film 11 and the resist film 13.

[0020] Step S102b includes forming an opening pattern in the resist film 13. Step S102b is performed using, for example, exposure and development. The opening width of the opening pattern is, for example, 100 nm or less, preferably less than 50 nm, and more preferably less than 20 nm.

[0021] The exposure includes irradiating a portion of the resist film 13 with light. The exposure is preferably EUV (Extreme Ultra Violet) exposure, as will be described in detail later. The EUV exposure includes irradiating a portion of the resist film 13 with EUV light. The wavelength of EUV light is about 13.5 nm. By using EUV exposure, the opening pattern of the resist film 13 can be made finer.

[0022] The development includes dissolving a part or a remainder of the resist film 13 in a developer. The resist film 13 may be either a positive type or a negative type. In the case of a positive type, the exposed part dissolves in the developer. In the case of a negative type, the unexposed part dissolves in the developer. The development may be performed in a vacuum using a gas.

[0023] By performing steps S102a and S102b, an etching mask for etching a portion of the inhibition film 11 can be formed. The etching mask may be formed by multi-patterning using a pattern formed by ArF exposure, for example. The etching mask may also be formed by nanoimprint lithography or electron beam lithography.

[0024] Step S102c includes etching a part of the inhibition film 11 by using the opening pattern of the resist film 13. The etching of the inhibition film 11 may be either dry etching or wet etching. The dry etching may be either plasma etching or thermal etching.

[0025] The inhibition film 11 is a film containing boron (B). Boron (B) halides, which are by-produced by etching, are more likely to volatilize in a vacuum than halides of the first element X1, similar to halides of Si or C, and can be easily processed by plasma etching or thermal etching, making it possible to form a fine pattern of the inhibition film 11. Boron (B) halides are highly volatile and are unlikely to remain on the inner walls of the processing vessel and are unlikely to reattach to the substrate 10 and become particles or etching defects.

[0026] The plasma etching is performed using, for example, CHF ３ or CF４ In addition to the etching gas, H ２ Or O ２ An additive gas such as N ２ Alternatively, a dilution gas such as Ar may be used. In plasma etching, the temperature of the substrate 10 is preferably 100° C. or less.

[0027] Thermal etching is performed using, for example, Cl ２ or ClF ３ In addition to the etching gas, N ２ Alternatively, a dilution gas such as Ar may be used. In thermal etching, the temperature of the substrate 10 is preferably 150° C. or higher.

[0028] Wet etching is performed using, for example, HF or HNO ３ A chemical solution is used in which a solute that contributes to etching, such as the above, is dissolved in a solvent. The solvent is, for example, water or an organic solvent.

[0029] Step S102d includes removing the resist film 13. Note that, instead of or in addition to removing the resist film 13, step S102d may include removing a hard mask film (not shown).

[0030] Step S103 includes forming a pattern of a target film 14 on the substrate 10 using the remaining portion of the inhibitor film 11. The target film 14 includes a first element X1. The target film 14 is, for example, an oxide film, a nitride film, or a metal film. The target film 14 may include a compound of the first element X1 and a nonmetallic element X2. The nonmetallic element X2 may be oxygen or nitrogen. The target film 14 is a so-called difficult-to-etch material. The target film 14 is hardly formed on the inhibitor film 11, but is selectively formed on the substrate 10 inside the recess 12.

[0031] Step S103 includes supplying a source gas and a reactive gas to the substrate 10. The source gas contains a halide, and the halide contains a first element X1 and a halogen. The reactive gas reacts with an adsorbate of the source gas. In this embodiment, the source gas and the reactive gas are supplied alternately, but they may also be supplied simultaneously. A method of supplying the source gas and the reactive gas alternately is ALD (Atomic Layer Deposition). A method of supplying the source gas and the reactive gas simultaneously is CVD (Chemical Vapor Deposition).

[0032] The source gas contains a halide, and the halide contains a first element X1 and a halogen. The halogen is fluorine, chlorine, bromine, or iodine. The first element X1 is, for example, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Al, Zn, Ga, In, or Sn.

[0033] Specific examples of the source gas include TiCl ４ Gas, WCl ６ Gas, VCl ４ Gas, AlCl ３ Gas, MoCl ５ Gas, SnCl ４ gas, or HfCl ４ The source gas may be supplied together with a dilution gas. The dilution gas may be, for example, Ar gas or N ２ It's gas.

[0034] The source gas contains a halide, and the halide may contain a halide containing a semiconductor element Si or Ge in addition to a halide containing the first element X1. The halide containing a semiconductor element Si or Ge is, for example, SiCl ４ , SiHCl ３ , SiH ２ Cl ２ , SiH ３ Cl, Si ２ Cl ６ , Si ２ HCl ５ , GeCl ４ is.

[0035] The reactive gas contains a nonmetallic element X2 and reacts with the adsorbate of the source gas, thereby forming a target film 14. The target film 14 contains a compound of the first element X1 and the nonmetallic element X2. The reactive gas may be, for example, O ２ Gas, O ３ Gas, CO ２ Gas, N ２ O gas, NO gas, or H ２ The reactive gas may be supplied together with a dilution gas, such as Ar gas or N ２ The reactive gas may be in the form of plasma.

[0036] Alternatively, the reactive gas may be a reducing gas containing hydrogen, which reacts with the adsorbate of the source gas, thereby forming the target film 14. The target film 14 is a metal film containing the first element X1. The reactive gas may be, for example, H ２ , SiH ４ The reaction gas may be supplied together with a dilution gas, such as Ar gas or N ２ The reactive gas may be in the form of plasma.

[0037] An example of selectively forming a target film 14 using the plasma ALD method will be described. Here, the case where the target film 14 is an oxide film will be described, but the target film 14 may also be a nitride film or a metal film. When the target film 14 is an oxide film, the reactive gas contains oxygen. When the target film 14 is a nitride film, the reactive gas contains nitrogen. When the target film 14 is a metal film, the reactive gas is a reducing gas containing hydrogen.

[0038] To selectively form the target film 14 by the plasma ALD method, it is important that the source gas be weakly adsorbed to the inhibitor film 11. In other words, it is important that the source gas adsorbed on the inhibitor film 11 is desorbed from the inhibitor film 11 by collision or reaction with the plasma-converted reactive gas without promoting the formation of the target film 14.

[0039] The ease with which the source gas adsorbed onto the inhibitor film 11 is desorbed varies depending on the strength of adsorption of the source gas onto the inhibitor film 11 and on the material of the inhibitor film 11. The ease with which the source gas adsorbed onto the inhibitor film 11 is desorbed also varies depending on whether the source gas is dissociated by reaction with atoms on the surface of the inhibitor film 11 and becomes molecules that are easily oxidized, nitrided, or reduced in a subsequent reaction.

[0040] When the reactive gas contains oxygen, oxygen ions or oxygen radicals are generated by converting the reactive gas into plasma. The oxygen ions are accelerated by the potential of the plasma and collide with the inhibitor film 11 and the substrate 10. The reactive gas may contain nitrogen, and nitrogen ions or nitrogen radicals may be generated, which collide with the inhibitor film 11 and the substrate 10. The reactive gas may also contain hydrogen, and hydrogen ions or hydrogen radicals may be generated, which collide with the inhibitor film 11 and the substrate 10.

[0041] Halides adsorbed on the substrate 10, which is substantially free of boron, are either sufficiently strongly adsorbed or dissociated into easily oxidizable molecules, which are easily oxidized by collision with oxygen ions or oxygen radicals. Therefore, it is believed that an oxide film will be formed on the substrate 10. Similarly, a nitride film can be formed on the substrate 10. Similarly, a metal film can be formed on the substrate 10.

[0042] On the other hand, the halides adsorbed on the inhibitor film 11 containing boron are either weakly adsorbed or not dissociated into easily oxidizable molecules, and therefore, even if they remain adsorbed on the inhibitor film 11, they are knocked off and desorbed by the collision of oxygen ions or oxygen radicals. Therefore, it is believed that the formation of an oxide film does not proceed on the inhibitor film 11. Similarly, it is believed that the formation of a nitride film does not proceed on the inhibitor film 11. Similarly, it is believed that the formation of a metal film does not proceed on the inhibitor film 11.

[0043] One possible reason why the formation of an oxide film does not progress on the inhibitor film 11 is that the inhibitor film 11 is etched by collisions of oxygen ions or oxygen radicals, and the halide on the inhibitor film 11 is lifted off along with the inhibitor film 11. A similar reason may be why the formation of a nitride film does not progress on the inhibitor film 11. Also, a similar reason may be why the formation of a metal film does not progress on the inhibitor film 11.

[0044] The reaction gas is O ３ The gas may be used without being converted into plasma. ３ The gas collides with the heated substrate 10 and the inhibitory film 11, generating oxygen radicals. The halide adsorbed on the substrate 10, which contains substantially no boron, is oxidized by the oxygen radicals. Therefore, the formation of an oxide film progresses on the substrate 10. On the other hand, the halide adsorbed on the inhibitory film 11, which contains boron, is not dissociated and therefore is less likely to react, so an oxide film is not formed. Therefore, the formation of an oxide film does not progress on the inhibitory film 11.

[0045] The halide adsorbed on the inhibitor film 11 is difficult to decompose by collision with oxygen ions or oxygen radicals. For example, TiCl ４ Halides such as Ti[N(CH ３ ) ２ ] ４ Similarly, halides are less likely to be decomposed by collision with nitrogen ions or nitrogen radicals, or hydrogen ions or hydrogen radicals, than organometallic complexes.

[0046] In order to desorb the halide adsorbed on the inhibitor film 11 from the inhibitor film 11, it is important that the halide is not easily decomposed by collision with oxygen ions or oxygen radicals, or collision with nitrogen ions or nitrogen radicals, or collision with hydrogen ions or hydrogen radicals. Therefore, a gas containing a halogen is suitable as the source gas.

[0047] In the plasma CVD method, which converts both halide and oxygen into plasma, oxygen ions or oxygen radicals are generated, and the halide dissociates, generating active species such as ions or radicals from the halide. The active species generated from the halide are highly reactive. Therefore, it is thought that the film formation reaction tends to proceed not only on the substrate 10 but also on the inhibitor film 11, resulting in a loss of selectivity. To achieve selectivity, it is preferable to use the plasma ALD method.

[0048] In step S103, the temperature of the substrate 10 may be controlled to 100°C or higher to promote desorption of the source gas from the inhibitor film 11. If the temperature of the substrate 10 is lower than 100°C, the source gas may not be sufficiently desorbed from the inhibitor film 11 and may be physically adsorbed, resulting in the target film 14 being formed on the inhibitor film 11 as well. The temperature of the substrate 10 is preferably 300°C or higher. The temperature of the substrate 10 is preferably 800°C or lower.

[0049] In step S103, the target film 14 is selectively formed on the substrate 10 inside the recess 12, with little or no formation on the inhibition film 11. The thickness of the target film 14 is approximately the same as the depth of the recess 12 in FIG. 2 , but it may be smaller or larger than the depth of the recess 12. The target film 14 may have a structure divided into islands or a structure connected in a network.

[0050] The target film 14 does not grow from the side surface of the recess 12 (e.g., the side surface of the inhibition film 11), but grows vertically from the bottom surface of the recess 12 (e.g., the surface of the substrate 10). In this embodiment, by forming a pattern without dry etching the target film 14, it becomes easy to form a fine vertical pattern of the target film 14 made of a difficult-to-etch material containing the first element X1. This solves the problem that the side surface of the pattern of the target film 14 tends to have a tapered shape as shown in FIG.

[0051] Furthermore, when the target film 14 is composed of a compound containing two or more first elements X1, or a compound containing the first element X1 and a semiconductor element, it is believed that selective patterning from the bottom surface of the recess 12 will not alter the surface composition or film quality of the target film 14. When the target film 14 containing multiple elements is formed by film deposition using two or more source gases containing the first element X1, or a gas containing the first element X1 and a gas containing a semiconductor element, it is possible to control the surface composition or film quality without being affected by the volatility of each element or the ease of removal by sputtering, by not using dry etching, and the target film 14 can be formed into a pattern having properties expected for a device.

[0052] By selectively forming the target film 14, which is made of a difficult-to-etch material containing the first element X1, as a pattern from the bottom surface of the recess 12, it is believed that the surface of the target film 14 will not be damaged by ion bombardment and the composition or film quality will not be altered. When the target film 14 is formed by film deposition, by not using dry etching, it is possible to avoid strong ion bombardment into the target film 14, it is possible to control the surface composition or film quality, and it is possible to form the target film 14 into a pattern having characteristics expected for a device.

[0053] By forming the target film 14 on the substrate 10, the target film 14 is deposited on the inner wall of the processing vessel, but this deposition is more stable than the adhesion of halides to the inner wall of the processing vessel that occurs when dry etching a material that is difficult to etch, and is less likely to re-adhere to the substrate 10 as particles and cause wafer defects. Furthermore, the target film 14 deposited on the inner wall of the processing vessel when formed is stable and less likely to peel off, which is thought to enable a longer cleaning cycle for the processing vessel and higher productivity.

[0054] In this embodiment, the target film 14 is a single layer, but it may be multiple layers. The multiple layers are formed by changing the combination of source gas and reactive gas. The multiple layers are not particularly limited, but may, for example, have a TiN layer, an HfO layer, and a TiN layer in this order on the substrate 10. Note that all of the multiple layers may be formed of a difficult-to-etch material, or only some of the layers may be formed of a difficult-to-etch material.

[0055] Forming a pattern in the target film 14 using the inhibitor film 11 is particularly effective when the pattern is fine. This is because it is particularly difficult to form a fine pattern in the target film 14 by etching when the target film 14 contains a material that is difficult to etch. Therefore, forming a pattern in the target film 14 using the inhibitor film 11 is particularly effective when EUV exposure is used.

[0056] Step S104 includes removing the inhibitor film 11 remaining after forming the target film 14. Step S104 is performed in the same manner as step S102c, and therefore a detailed description thereof will be omitted. The inhibitor film 11 contains boron (B). B atoms are formed by a halide, for example, BF ３ or BCl ３ These are highly volatile and easily etched, so that it is possible to remove the inhibitor film 11 while leaving the target film 14.

[0057] As shown in FIG. 4 , the film formation method may further include steps S105 to S107. Step S105 includes forming a second target film 15 at least in the region from which the inhibition film 11 was removed in step S104. The second target film 15 may be formed not only on the substrate 10 but also on the target film 14. Step S106 includes etching a portion of the second target film 15 to expose the target film 14. Step S106 may be performed by forming an etching mask on the top using an exposure process, as in step S102, or by exposing the target film 14 using etch-back, which uniformly etched the entire surface with plasma, or by removing surface material using CMP. Step S107 includes forming a third target film 16 on the target film 14 and the second target film 15.

[0058] The target film 14, the second target film 15, and the third target film 16 are made of different materials and have different functions. The target film 14 is, for example, at least a part of a memory element. The memory element has, for example, an oxide film and an electrode. The oxide film is, for example, TiO ２ Membrane and Ta ２ O ５ film and HfO ２ The electrode includes, for example, at least one of a TiN film and a TaN film. The second target film 15 is an element isolation film. The element isolation film includes, for example, a SiO film. The SiO film may contain elements other than Si and O (for example, B, N, or C). The third target film 16 is, for example, a conductive film, and is used as an electrode or wiring.

[0059] A film formation method according to a modified example will be described with reference to Fig. 5. Differences from the film formation method shown in Fig. 2 will be mainly described below. As shown in Fig. 5, in step S102, the recess 12 may be formed not only in the inhibitor film 11 but also in the substrate 10. In this case, the side surface of the recess 12 is formed by the inhibitor film 11 and the substrate 10. On the other hand, the bottom surface of the recess 12 is formed by the substrate 10.

[0060] 5 , in step S103, the target film 14 grows from the side surfaces of the recess 12 (e.g., the side surfaces of the inhibition film 11) and the bottom surface of the recess 12, and is formed with a U-shaped cross section along the side surfaces and the bottom surface of the recess 12. In this modification, the target film 14 is a single layer, but may be multiple layers.

[0061] 6 , the film forming method may further include step S105. Step S105 includes forming a second target film 15 at least in the region where the inhibition film 11 has been removed in step S104. The second target film 15 may be formed not only on the substrate 10 but also on the target film 14. The second target film 15 may fill the interior of the recess 12.

[0062] The target film 14 and the second target film 15 are formed of different materials and have different functions. The target film 14 is, for example, at least a part of a memory element. The memory element has, for example, an oxide semiconductor film and a gate insulating film. The oxide semiconductor film includes, for example, IGZO. The gate insulating film includes, for example, HfO２ The second target film 15 is, for example, a conductive film, and is used as an electrode or wiring.

[0063] Although the embodiments of the film forming method according to the present disclosure have been described above, the present disclosure is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

[0064] This application claims priority based on Japanese Patent Application No. 2024-030894, filed with the Japan Patent Office on March 1, 2024, the entire contents of which are incorporated herein by reference.

[0065] 10 Substrate 11 Inhibition film 12 Recess 14 Target film

Claims

1. A film formation method comprising forming a pattern of a target film containing a first element X1 on a substrate, the method comprising: forming an inhibitory film on the substrate that contains boron and inhibits the formation of the target film; forming a recess in a part of the inhibitory film that penetrates the inhibitory film; using the remaining part of the inhibitory film to form a pattern of the target film on the substrate; and removing the inhibitory film that remains after the target film is formed, wherein the first element X1 is a transition metal element, Al, Ga, In, or Sn, and forming the target film comprises supplying to the substrate a source gas containing the first element X1 and a halogen, and a reactive gas that reacts with an adsorbate of the source gas.

2. The film forming method according to claim 1, wherein the first element X1 is Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Zn, Al, Ga, In, or Sn.

3. The film forming method according to claim 1 or 2, wherein the target film further contains at least one of Si and Ge in addition to the first element X1.

4. The film forming method according to claim 1 or 2, wherein the target film contains a compound of the first element X1 and oxygen, and the reactive gas contains oxygen.

5. The film forming method according to claim 1 or 2, wherein the target film contains a compound of the first element X1 and nitrogen, and the reactive gas contains nitrogen.

6. The film forming method according to claim 1 or 2, wherein the target film is made of a metal containing the first element X1, and the reactive gas contains hydrogen.

7. The film forming method according to claim 1 or 2, wherein forming the recess in a part of the inhibition film includes using EUV exposure.

8. The film forming method according to claim 1 or 2, wherein forming the recess in a part of the inhibition film includes using multi-patterning.

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