Film forming methods and film forming apparatus

Abstract

This invention provides a method and apparatus for forming a metal oxide film with low impurities. The method for forming a metal oxide film on a substrate within a processing container includes: a step of supplying a feed gas containing an organometallic precursor into the processing container; a step of removing residual gas remaining in the processing container after the feed gas supply step; a step of supplying an oxidant to the processing container to oxidize the feed gas; a step of removing residual gas remaining in the processing container after the oxidant supply step; and a step of supplying a hydrogen-containing reducing gas into the processing container simultaneously with or successively after the feed gas supply step.

Description

Technical Field

[0001] This invention relates to film-forming methods and film-forming apparatus. Background Technology

[0002] As a method for forming metal oxide films, atomic layer deposition (ALD) is known, in which organometallic precursors and oxidants are alternately supplied. Patent Document 1 describes the sequential formation of individual metal oxide films such as IGZO using the ALD method, and describes how the content ratio in the thickness direction of the multi-metal oxide film can be changed by varying the frequency of the formation steps of specific metal oxide films.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 2016-511936 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] The present invention provides a film-forming method and an apparatus capable of forming a metal oxide film with few impurities.

[0008] Technical solutions for solving technical problems

[0009] One embodiment of the present invention provides a film-forming method for forming a metal oxide film on a substrate within a processing container, comprising: a step of supplying a raw material gas containing an organometallic precursor into the processing container; a step of removing residual gas remaining in the processing container after the step of supplying the raw material gas; a subsequent step of supplying an oxidant to the processing container to oxidize the raw material gas; a step of removing residual gas remaining in the processing container after the step of supplying the oxidant; and a step of supplying a hydrogen-containing reducing gas into the processing container simultaneously with or successively after the step of supplying the raw material gas.

[0010] Invention Effects

[0011] According to the present invention, a film-forming method and a film-forming apparatus capable of forming a metal oxide film with few impurities are provided. Attached Figure Description

[0012] Figure 1 This is a timing diagram showing the gas supply timing in an example of the film-forming method of the first embodiment.

[0013] Figure 2This is a timing diagram showing the gas supply timing in another example of the film-forming method of the first embodiment.

[0014] Figure 3 This is a graph used to illustrate the effect of impurity reduction when H2 gas is supplied.

[0015] Figure 4 This is a diagram used to illustrate the reduction effect of H2O when H2 gas is supplied.

[0016] Figure 5 This is a timing diagram showing the gas supply timing in another example of the film-forming method of the first embodiment.

[0017] Figure 6 This is a timing diagram showing the gas supply timing in an example of the film-forming method of the second embodiment.

[0018] Figure 7 This is a timing diagram showing the gas supply timing in another example of the film-forming method of the second embodiment.

[0019] Figure 8 This is a timing diagram showing the gas supply timing in yet another example of the film-forming method of the second embodiment.

[0020] Figure 9 This is a schematic cross-sectional view showing a specific example of the multi-metal oxide film formed in the second embodiment, namely the IGZO film.

[0021] Figure 10 This indicates that InO is formed using the conventional ALD method. x The graph shows the relationship between substrate temperature and film thickness, and the relationship between substrate temperature and impurity concentration during film formation.

[0022] Figure 11 This indicates that GaO films are formed using the conventional ALD method. x The graph shows the relationship between substrate temperature and film thickness, and the relationship between substrate temperature and impurity concentration during film formation.

[0023] Figure 12 This indicates the formation of ZnO using the conventional ALD method. x The graph shows the relationship between substrate temperature and film thickness, and the relationship between substrate temperature and impurity concentration during film formation.

[0024] Figure 13 This indicates that in the formation of GaO film x A diagram showing the de-icing of the temperature region of the ALD window under the condition of simultaneous supply of triethylgallium and H2 gas during membrane fabrication.

[0025] Figure 14 This is a cross-sectional view showing an example of a film-forming apparatus used in a film-forming method.

[0026] Explanation of reference numerals in the attached figures

[0027] 1: Chamber

[0028] 2: Base

[0029] 3: Spray head

[0030] 4: Exhaust section

[0031] 5: Gas supply mechanism

[0032] 6: Control Department

[0033] 51: Ga feedstock gas supply source

[0034] 52: Zn feedstock gas supply source

[0035] 53: In raw material gas supply source

[0036] 54, 55, 58: Continuous Ar gas supply source

[0037] 56: H2 gas supply source

[0038] 57: O3 gas supply source

[0039] 100: Film-forming device

[0040] 200: substrate

[0041] 201:InO x membrane

[0042] 202: GaO x membrane

[0043] 203:ZnO x membrane

[0044] W: substrate. Detailed Implementation

[0045] Hereinafter, the embodiments will be described with reference to the accompanying drawings.

[0046] <Film Formation Method>

[0047] First, the implementation method of the film-forming method will be described.

[0048] [First Implementation Method]

[0049] In this embodiment, a metal oxide film is formed using the ALD method while the substrate is housed in a processing container.

[0050] Figure 1 This is a timing diagram illustrating the gas supply timing in an example of the film-forming method of the first embodiment. For example... Figure 1As shown, the film-forming method of the first embodiment includes steps S1, S2, S3, S4, and S5. The sequence of steps S1 to S4 is repeated for a desired number of cycles, and step S5 is performed in each cycle.

[0051] Step S1 is the step of supplying a feed gas (MO gas) containing an organometallic precursor into the processing container. The MO gas is generated, for example, by vaporizing a liquid or solid organometallic precursor. Step S2 is the step of purging the processing container after step S1 to remove any remaining gas. Step S3 is the step of supplying an oxidant into the processing container after step S2. Step S4 is the step of purging the processing container after step S3 to remove any remaining gas. Step S5 is the step of supplying a hydrogen-containing reducing gas, such as hydrogen (H2 gas), into the processing container. Figure 1 In the example, the supply of hydrogen-containing reducing gas in step S5 is performed simultaneously with the supply of MO gas in step S1. Additionally, in... Figure 1 In the example, it indicates that the supply period of the organometallic precursor coincides exactly with the supply period of the hydrogen-containing reducing gas, but "simultaneously" also includes cases where a portion of these periods coincide.

[0052] Figure 2 This is a timing diagram illustrating the gas supply timing in another example of the film-forming method of the first embodiment. This example shows a case where step S5 is performed immediately after step S1. Steps S1 to S4 and... Figure 1 The examples are the same.

[0053] The following is about Figure 1 and Figure 2 The sequence will be explained in more detail.

[0054] In step S1, MO gas is supplied into the processing container, causing the MO gas to be adsorbed onto the substrate surface. In the ALD method, a temperature range (ALD window) with a certain film formation rate (film thickness) is used to achieve saturated adsorption.

[0055] The organometallic precursor used in step S1 is a precursor formed by combining an organic ligand with a metal element of the metal oxide film to be formed. Examples of metal elements include indium, gallium, zinc, tin, aluminum, copper, titanium, vanadium, nickel, cobalt, manganese, and tungsten. Examples of organic ligands include alkyl groups such as CH3 or C2H5. In addition, amino groups, alkoxides (alkyl groups), and carbonyl groups can also be used as organic ligands.

[0056] In step S3, an oxidant is supplied into the processing container to oxidize the MO gas adsorbed on the substrate surface, forming a metal oxide film. The oxidant used in step S3 can be any oxidant that reacts with the MO gas to form a metal oxide; examples include ozone (O3), oxygen (O2), and water vapor (H2O).

[0057] The purging in steps S2 and S4 can be performed by evacuating the processing container, supplying purging gas to the processing container to remove residual gas, or both. As the purging gas, rare gases such as Ar, inert gases such as N2, etc., can be used. Figure 1 and Figure 2 The example illustrates a case where purge gas is continuously supplied as counter gas for purging.

[0058] In addition to H2 gas, the hydrogen-containing reducing gas used in step S5 can also be NH3, alcohols such as ethanol (C2H5OH), etc. Figure 1 The order (sequence) and Figure 2 The sequence has the following effect: by supplying a hydrogen-containing reducing gas, such as H2 gas, the hydrogen-containing reducing gas reacts with the organic ligands in the organometallic precursor, causing the organic ligands to detach and reducing impurities in the membrane. Figure 3 This example illustrates the use of triethylin as an organometallic precursor, O3 gas as an oxidant, and H2 gas as a hydrogen-containing reducing gas. In step S1, after triethylin is adsorbed onto the substrate, O3 gas is supplied in step S3 without supplying H2 gas. Figure 3 As shown in (a), the ethyl group (C2H5) as an organic ligand is prone to remain as an impurity. In contrast, step S5, which involves supplying H2 gas, is as follows: Figure 3 As shown in (b), the ethyl group is released from the adsorbed triethylin, which ends with hydrogen, thus reducing the generation of impurities in the subsequent oxidation step using O3 gas.

[0059] Furthermore, in the case where the organic ligand of such organometallic precursor is an alkyl group, the step of supplying a hydrogen-containing reducing gas is performed, thereby obtaining the product from CH4. x The terminal surface changes to an H-terminal surface, thus increasing its reactivity with oxidants and enabling oxidation reactions to occur in a short time.

[0060] Furthermore, when an oxidant is supplied to the CHx terminal surface, a large amount of moisture (H2O) is generated, thus requiring purging time. During purging, H2O is re-adsorbed onto, for example, the walls of pores formed on the substrate, leading to uneven surface reactions and potentially uneven film thickness. In contrast, supplying a hydrogen-containing reducing gas to make the substrate surface an H-terminal surface reduces the generation of H2O after oxidant supply, eliminating the aforementioned problems. For example, when O3 gas is supplied instead of a hydrogen-containing reducing gas while indium triethyl is vaporized and adsorbed, ... Figure 4 As shown in (a), each molecule produces 5 H₂O molecules. In contrast, when triethylin is adsorbed, H₂ gas is supplied as a hydrogen-containing reducing gas, followed by O₃ gas, as... Figure 4 As shown in (b), each molecule produces only 1 H2O.

[0061] When hydrogen-containing reducing gas and MO gas are supplied simultaneously, the thermal decomposition of organometallic precursors can be further promoted, thereby achieving the effect of lowering the film formation temperature.

[0062] Next, another example of the first embodiment will be described.

[0063] Figure 5 This is a timing diagram illustrating the gas supply timing in another example of the film-forming method of the first embodiment. In this example, it shows an instance where the mixing of hydrogen-containing reducing gas, such as H2 gas, with the oxidant can be reliably prevented. When an oxidant such as O3 gas is supplied while H2 gas remains in the processing container, an explosive reaction may occur. Therefore, in this example, the purging in step S2 is intensified to minimize the possibility of such reactions. For example, methods such as increasing the flow rate of the purging gas in step S2 and / or intensifying the exhaust gas during step S2 can be cited. Figure 5 In the example, the purge gas is kept flowing as a backflushing gas, and in step S2, additional purge gas is added from other pipelines to increase the purge gas flow rate, with depressurization only occurring during step S2. In the case of film formation using the ALD method, each step is short, therefore high-speed depressurization is required. Enhanced degassing can be achieved, for example, through high-speed APC opening control, high-speed intermittent control, etc., as described later.

[0064] [Second Implementation]

[0065] Next, the second embodiment will be described.

[0066] In this embodiment, with a substrate contained within a processing container, a multi-element metal oxide film is formed essentially by ALD (Alternating Deposition) of multiple metal oxide films, each containing a different metal. Taking a ternary alloy oxide film as an example, the process includes a first stage of forming a first metal oxide film by ALD, a second stage of forming a second metal oxide film by ALD, and a third stage of forming a third metal oxide film by ALD. Each stage essentially includes the same steps as in the first embodiment: supplying MO gas, purging residual gas, supplying an oxidant to the substrate, and purging residual gas again. These steps are then repeated as desired in each stage, and the first to third stages are repeated as desired. Furthermore, at least one of the first, second, and third stages includes a step of supplying a hydrogen-containing reducing gas to the substrate simultaneously with the MO gas supply step during each cycle.

[0067] Figure 6 This is a timing diagram illustrating the gas supply timing in an example of the film-forming method of the second embodiment. Figure 6 The example shown is an example of a ternary metal oxide film.

[0068] like Figure 6 As shown, the process includes a first stage (ST1) for forming a first metal oxide film, a second stage (ST2) for forming a second metal oxide film, and a third stage (ST3) for forming a third metal oxide film. Each stage has the same steps S1 to S4 as in the first embodiment. These steps are repeated X times in the first stage (ST1), Y times in the second stage (ST2), and Z times in the third stage (ST3). Furthermore, these ST1 to ST3 are repeated N times. This allows for control of the proportion and thickness of each oxide film. In this example, in the second stage (ST2), the supply of hydrogen-containing reducing gas in step S5 is performed simultaneously with the supply of MO gas in step S1.

[0069] in addition, Figure 7 This represents an example of step S5 performed in the first stage (ST1) and the second stage (ST2). Figure 8 This represents an example of performing step S5 in all stages from the first stage (ST1) to the third stage (ST3). In these cases, such as... Figure 7 , Figure 8 As shown, the supply of hydrogen-containing reducing gas can also be varied at different stages.

[0070] In this embodiment, the step of supplying a hydrogen-containing reducing gas, similar to the first embodiment, also achieves the effect of reducing impurities, from CH... xThe change in the terminal surface results in an increased reactivity with the oxidant due to the H-terminal surface and an effect of suppressing the production of H2O. These effects can be obtained not only when an organometallic precursor and a hydrogen-containing reducing gas are simultaneously supplied, but also in the case of the first embodiment. Figure 2 Examples can also be obtained when they are supplied successively.

[0071] Furthermore, as described above, by simultaneously supplying a hydrogen-containing reducing gas to the substrate during the step of supplying the organometallic precursor, the same effect of promoting the thermal decomposition of the organometallic precursor and thus lowering the film-forming temperature can be achieved. In this embodiment, utilizing this effect of lowering the film-forming temperature, as will be explained below, the film-forming temperature of each metal oxide film can be reduced when forming a multi-metal oxide film by the ALD method.

[0072] In the case of forming a multi-metal oxide film such as in this embodiment using the ALD method, from the viewpoint of cycle time, it is preferable to perform the process within the same processing container and at the same temperature. On the other hand, in the ALD method, the temperature range (ALD window) where the precursor is saturated with adsorption and the film formation rate (film thickness) is constant becomes the optimal film formation temperature, at which the impurity concentration also decreases. However, the ALD window largely depends on the precursor used, so sometimes the optimal film formation temperature of each metal oxide film constituting the multi-metal oxide film is different. Therefore, in this embodiment, in at least one of the first, second, and third stages, in each cycle, a step of supplying a hydrogen-containing reducing gas to the substrate is performed simultaneously with the step of supplying MO gas, promoting the thermal decomposition of the organometallic precursor and thus lowering the film formation temperature. Therefore, when forming a metal oxide film in the high temperature range of the ALD window, the film formation temperature is lowered by simultaneously supplying a hydrogen-containing reducing gas with MO gas, thereby enabling the appropriate ALD formation of multi-metal oxide films at the same temperature. Furthermore, similar to the first embodiment, "simultaneously" also includes cases where the supply period of the organometallic precursor coincides with a portion of the supply period of the hydrogen-containing reducing gas.

[0073] Next, a specific example of the second embodiment will be described. Here, as a multi-metal oxide film, InO is used. x GaO x ZnO x The following explanation will be based on an example of an oxide semiconductor thin film, namely an InGaZnO film (IGZO film). For instance, if the first metal oxide film is InO... x The second metal oxide film is GaO x The third metal oxide film is ZnO. x In the case of film formation via ALD, such as Figure 9The IGZO film shown is formed by repeating steps S1 to S4 for X, Y, and Z cycles respectively, to deposit an InO film on a substrate 200 with an oxide film (SiO2 film) on its surface. x Membrane 201, GaO x Membrane 202, ZnO x A stacked film of film 203 is formed. Then, the deposition of this stacked film is repeated N times as one cycle to form an IGZO film of the desired thickness. As an organometallic precursor, for example, triethylindium, triethylgallium, or diethylzinc can be used.

[0074] Figures 10-12 These represent InO films formed using the conventional ALD method. x membrane, GaO x membrane, ZnO x The graph shows the relationship between substrate temperature and film thickness, and the relationship between substrate temperature and impurity concentration. The substrate temperature is represented by the temperature of the stage on which the substrate is placed. The impurity concentration is represented by the concentrations of hydrogen (H) and carbon (C). Here, triethylin, triethylgallium, and diethylzinc are used as organometallic precursors (organo-In, organo-Ga, and organo-Zn), and O3 gas is used as the oxidant. As described above, the film deposition rate becomes constant, and the ALD window, which represents a temperature region with low impurity concentration, becomes the optimal film deposition temperature for ALD. The film deposition rate is proportional to the film thickness, therefore... Figures 10-12 As shown, the temperature range of the ALD window is in InO x The temperature in the film is around 200~250℃, in GaO x The temperature in the membrane is around 250~300℃, in ZnO x The temperature in the membrane is around 200°C. Thus, InO... x membrane, GaO x membrane, ZnO x The optimal film-forming temperature varies, so it is difficult to achieve the best film formation when performing ALD film formation on IGZO film at the same temperature.

[0075] In contrast, for example, in GaO, which forms a second oxide film... x When the membrane is in place, such as Figure 6 As shown, by simultaneously supplying a reducing gas containing Ga feedstock gas and hydrogen, such as H2 gas, it is possible to form a GaO film. x The film formation process promotes the thermal decomposition of organometallic precursors and lowers the temperature range of the ALD window. Therefore, during IGZO film formation, the optimal film formation temperature for each metal oxide film can be varied, allowing for the formation of IGZO films at the same temperature through optimal ALD deposition.

[0076] Alternatively, it could be GaO, in addition to serving as a second oxide film during film formation. xAt that time, InO was still forming a film as the first oxide film. x During membrane processing, both In feed gas and hydrogen-containing reducing gas are supplied simultaneously, thereby allowing the ZnO to react with the feed gas. x The InO membrane has a higher temperature range compared to the ALD window. x The film formation temperature also decreases. In this case, by making the film formation temperature higher than that of GaO... x InO film formed at low temperature x The amount of hydrogen-containing reducing gas during film formation is greater than that of GaO film formation. x The optimal amount of hydrogen-containing reducing gas during membrane formation allows for the formation of IGZO membranes under more suitable conditions.

[0077] Alternatively, it can also be used in film-forming InO x membrane, GaO x membrane, ZnO x During film formation, a hydrogen-containing reducing gas is supplied throughout. This results in reduced impurities and H2O during the formation of all metal oxide films, and also lowers the overall film formation temperature. Furthermore, by optimizing the amount of hydrogen-containing reducing gas during the formation of each metal oxide film, the optimal film formation temperature for each metal oxide film can be made consistent, allowing IGZO films to be formed at the same temperature through optimal ALD film formation.

[0078] The effect of reducing film formation temperature using hydrogen-containing reducing gases, as described above, can be verified using activation energy. For example, in the formation of GaO... x When using triethylgallium in a membrane, the activation energy for the dissociation of the ethyl group is +2.77 eV, while the activation energy for the reaction with hydrogen is +1.59 eV. Therefore, by simultaneously supplying triethylgallium gas and a hydrogen-containing reducing gas such as H2, the thermal decomposition of triethylgallium is promoted. Figure 13 As shown, the temperature range of the ALD window can be lowered, thus lowering the film formation temperature. Furthermore, it is known that when using triethylindium and diethylzinc, the activation energies for ethyl bond dissociation are +2.32 eV and 2.07 eV, respectively, and the ease of thermal decomposition is Zn (diethylzinc) > In (triethylindium) > Ga (triethylgallium). Additionally, it is known that the activation energies for the reaction of triethylindium and diethylzinc with hydrogen are +1.56 eV and 1.82 eV, respectively, and their thermal decomposition can be promoted using hydrogen-containing reducing gases such as H2.

[0079] Additionally, in this example, of course, in the film-forming InO x membrane, GaO x membrane, ZnO x When at least one of the membranes is present, by implementing the step of supplying a hydrogen-containing reducing gas, the basic effects such as reducing the aforementioned impurities can be obtained.

[0080] <Film Forming Device>

[0081] Next, an example of a film-forming apparatus capable of implementing the film-forming method described above will be described. Figure 14 This is a cross-sectional view showing an example of a film-forming apparatus. Here, as organometallic precursors, an example of an IGZO film-forming apparatus is given, which uses an organoGa precursor, an organoZn precursor, and an organoIn precursor, uses O3 gas as an oxidant, Ar gas as a purge gas, and H2 gas as a hydrogen-containing reducing gas.

[0082] The film-forming apparatus 100 has a chamber 1 serving as a processing container, a base (platform) 2, a spray head 3, an exhaust unit 4, a processing gas supply mechanism 5, and a control unit 6.

[0083] The chamber 1, which serves as the processing container, is made of a generally cylindrical metal. An inlet / outlet 26 is formed on the side wall of the chamber 1 for feeding and feeding the substrate W into and out of the vacuum transport chamber (not shown) using a transport mechanism (not shown). The inlet / outlet 26 can be opened and closed by a gate G.

[0084] An annular exhaust pipe 28 with a rectangular cross-section is provided on the main body of chamber 1. A slit 28a is formed along the inner circumferential surface of exhaust pipe 28. In addition, an exhaust port 28b is formed on the outer wall of exhaust pipe 28. A top wall 29 is provided on the upper surface of exhaust pipe 28 to close the upper opening of chamber 1. The top wall 29 and exhaust pipe 28 are airtightly sealed by a sealing ring 30.

[0085] The base 2, serving as a mounting stage, is used to mount the substrate W within the chamber 1. The base 2 is a horizontally arranged circular plate of a size corresponding to the substrate W. The base 2 is supported by a support member 33. A heater 31 for heating the substrate W is embedded inside the base 2. The heater 31 is powered by a heater power supply (not shown) and generates heat. Furthermore, by controlling the output of the heater 31, the substrate W can be controlled to a desired temperature. A ceramic covering member 32 is provided on the base 2 to cover the outer periphery and sides of the substrate mounting surface.

[0086] The support member 33 of the support base 2 extends downward from the center of the bottom surface of the base 2 through a hole formed in the bottom wall of the chamber 1, and its lower end is connected to the lifting mechanism 34. The base 2 can be lifted by the lifting mechanism 34 via the support member 33. Figure 14The solid line indicates the processing position, while the two dashed lines below it indicate the transport position of the substrate. Furthermore, the lifting mechanism 34 can move up and down at high speed during purging. A flange 35 is installed below the chamber 1 of the support member 33, and a bellows 36 is provided between the bottom surface of the chamber 1 and the flange 35 to separate the atmosphere inside the chamber 1 from the external gas, and which expands and contracts with the lifting and lowering movement of the base 2.

[0087] Near the bottom surface of chamber 1, three (two shown only) support pins 37 are provided, protruding upwards from the lifting plate 37a. The support pins 37 can be raised and lowered via the lifting plate 37a through a lifting mechanism 38 located below chamber 1, and can protrude from and be submerged relative to the upper surface of the base 2 by passing through the through hole 22 provided in the base 2 when it is in the transport position. This allows for the transfer of the substrate W between the substrate transport mechanism (not shown) and the base 2.

[0088] The spray head 3 is used to supply processing gas into the chamber 1 in a spray-like manner. It is disposed on the upper part of the chamber 1 opposite to the base 2 and has a diameter approximately the same as the base 2. The spray head 3 has a main body 39 fixed to the top wall 29 of the chamber 1 and a spray plate 40 connected below the main body 39. A gas diffusion space 41 is formed between the main body 39 and the spray plate 40.

[0089] Multiple gas dispersion components 42 are provided within the gas diffusion space 41. Multiple gas release holes are formed around the gas dispersion components 42. Each gas dispersion component 42 is connected to one end of a plurality of gas supply passages 43 provided on the main body 39. The other end of each gas supply passage 43 is connected to a diffuser 44 formed in the center of the upper surface of the main body 39. In addition, a gas inlet hole 45 is provided in the center of the main body 39, extending from its upper surface into the diffuser 44.

[0090] A downwardly protruding annular protrusion 40b is formed at the periphery of the spray plate 40, and a gas release hole 40a is formed on the flat surface inside the annular protrusion 40b of the spray plate 40. When the base 2 is in the processing position, a processing space S is formed between the spray plate 40 and the base 2, and the annular protrusion 40b approaches the upper surface of the cover member 32 of the base 2 to form an annular gap 48.

[0091] The exhaust unit 4 includes: an exhaust pipe 46 connected to the exhaust port 28b of the exhaust pipe 28; an exhaust mechanism 47 equipped with a vacuum pump connected to the exhaust pipe 46; and an automatic pressure control valve (APC) 47a installed on the exhaust pipe. During processing, the gas in the chamber 1 reaches the exhaust pipe 28 through the gap 28a, and is exhausted from the exhaust pipe 28 through the exhaust pipe 46 by the exhaust mechanism 47 of the exhaust unit 4. At this time, the pressure in the chamber 1 can be controlled by the opening degree of the automatic pressure control valve (APC) 47a.

[0092] The processing gas supply unit 5 includes a Ga raw material gas supply source 51, a Zn raw material gas supply source 52, an In raw material gas supply source 53, an H2 gas supply source 56, an O3 gas supply source 57, a first Ar gas supply source 54, a second Ar gas supply source 55, and a third Ar gas supply source 58. The Ga raw material gas supply source 51 supplies Ga raw material gas by vaporizing an organic Ga precursor, such as triethylgallium. The Zn raw material gas supply source 52 supplies Zn raw material gas by vaporizing an organic Zn precursor, such as diethylzinc. The In raw material gas supply source 53 supplies In raw material gas by vaporizing an organic In precursor, such as triethylindium. The O3 gas supply source 57 generates O3 gas from O2 gas using an ozone generator. The first Ar gas supply source 54, the second Ar gas supply source 55, and the third Ar gas supply source 58 supply Ar gas as purge gas.

[0093] Ga raw material gas supply source 51, Zn raw material gas supply source 52, In raw material gas supply source 53, H2 gas supply source 56, and O3 gas supply source 57 are respectively connected to one end of Ga raw material gas supply pipeline 61, Zn raw material gas supply pipeline 62, In raw material gas supply pipeline 63, H2 gas supply pipeline 66, and O3 gas supply pipeline 67.

[0094] The first Ar gas supply source 54, the second Ar gas supply source 55, and the third Ar gas supply source 58 are respectively connected to the first continuous Ar gas supply line 64, the second continuous Ar gas supply line 65, and the third continuous Ar gas supply line 68. During processing, the first continuous Ar gas supply line 64, the second continuous Ar gas supply line 65, and the third continuous Ar gas supply line 68 consistently supply Ar gas as counter purge gas.

[0095] The other end of Ga raw material gas supply line 61 is connected to Zn raw material gas supply line 62. The other end of the first continuous Ar gas supply line 64 is connected to Zn raw material gas supply line 62 via Ga raw material gas supply line 61. The other end of the second continuous Ar gas supply line 65 is connected to In raw material gas supply line 63. The other end of H2 gas supply line 66 is connected to In raw material gas supply line 63 via the second continuous Ar gas supply line 65. The other end of the third continuous Ar gas supply line 68 is connected to O3 gas supply line 67. The other ends of Zn raw material gas supply line 62, In raw material gas supply line 63, and O3 gas supply line 67 merge with the confluence line 69, which is connected to gas inlet 45.

[0096] The first rapid purging line 64a branches off from the first continuous Ar gas supply line 64, the second rapid purging line 65a branches off from the second continuous Ar gas supply line 65, and the third rapid purging line 68a branches off from the third continuous Ar gas supply line 68. Furthermore, the lower ends of the first rapid purging line 64a, the second rapid purging line 65a, and the third rapid purging line 68a merge with the first continuous Ar gas supply line 64, the second continuous Ar gas supply line 65, and the third continuous Ar gas supply line 68, respectively. The first rapid purging line 64a, the second rapid purging line 65a, and the third rapid purging line 68a are used to supply a large amount of Ar gas for rapid purging during the purging process.

[0097] A flow meter 71, a buffer tank 81, and a valve 91 are installed from the upstream side of the Ga raw material gas supply line 61. A flow meter 72, a buffer tank 82, and a valve 92 are installed from the upstream side of the Zn raw material gas supply line 62. A flow meter 73, a buffer tank 83, and a valve 93 are installed from the upstream side of the In raw material gas supply line 63. A flow controller 76, a buffer tank 84, and a valve 96 are installed from the upstream side of the H2 gas supply line 66. A flow controller 77, a buffer tank 85, and a valve 97 are installed from the upstream side of the O3 gas supply line 67. Buffer tanks 81-85 are used to temporarily store various gases. By storing gas in them and increasing the pressure therein, and then supplying the stored gas, a large flow rate of gas can be supplied to chamber 1.

[0098] Flow controllers 74 and 94, 75 and 95, and 78 and 98 are respectively installed from the upstream side of the first Ar gas supply source 54, the second Ar gas supply source 55, and the third Ar gas supply source 58. Additionally, flow controllers 74a and 94a, 75a and 95a, and 78a and 98a are respectively installed from the upstream side of the first rapid purge line 64a, the second rapid purge line 65a, and the third rapid purge line 68a.

[0099] Valves 91, 92, 93, 96, 97, 94a, 95a, and 98a function as ALD valves for switching gases during ALD operation and are composed of high-speed valves capable of opening and closing at high speeds.

[0100] Since triethylgallium, diethylzinc, and triethylindium used as organic Ga, organic Zn, and organic In precursors are liquids at room temperature, the Ga raw material gas supply source 51, Zn raw material gas supply source 52, and In raw material gas supply source 53 are equipped with mechanisms for vaporizing the liquid raw materials. For example, the Ga raw material gas supply source includes: a raw material container storing the organic Ga precursor as a liquid; a heating mechanism for heating the raw material container; and a carrier gas supply line for supplying carrier gas into the raw material container. Furthermore, the aforementioned Ga raw material gas supply line 61 is inserted into the raw material container, allowing the Ga raw material gas to be transported into the raw material gas supply line 61 using the carrier gas. The flow rate of the Ga raw material is controlled by a flow controller installed in the carrier gas supply line. The Zn raw material gas supply source 52 and In raw material gas supply source 53 are similarly configured.

[0101] In addition, the first to third rapid purging lines 64a, 65a, 68a and buffer tanks 81 to 85 are not required.

[0102] The control unit 6 is composed of a computer and includes a main control unit with a CPU, input devices, output devices, a display device, and a storage device (storage medium). The main control unit controls, for example, the opening and closing of valves, the flow rate of gas based on a flow controller, the opening degree of an APC pressure control valve, and the output of a heater that heats the substrate W. These controls are executed according to processing schemes stored in the storage medium built into the storage device.

[0103] Next, an example of a film-forming process using the film-forming apparatus 100 configured as described above will be explained.

[0104] The temperature of the base 2 is controlled in advance by the control unit 6 based on the heating of the heater 31, so that the temperature of the substrate W placed on the base 2 is the desired temperature.

[0105] In this state, firstly, the gate G is opened, and the substrate W is sent from the vacuum transport chamber into the chamber 1 using a conveying device (not shown), and placed on the base 2.

[0106] After placing the substrate W and allowing the conveying device to pass, the gate G is closed, causing the base 2 to rise to the processing position. Next, the exhaust section 4 is used to exhaust the air from the chamber 1, and valves 94, 95, and 98 are opened to continuously supply Ar gas into the processing space S of the chamber 1 via the first continuous Ar gas supply line 64, the second continuous Ar gas supply line 65, and the third continuous Ar gas supply line 68.

[0107] Then, while maintaining a continuous supply of Ar gas, InO films are continuously formed using the ALD method as shown below. x membrane, GaO x membrane, ZnO x The membrane is formed, and this membrane-forming cycle is repeated N times. InO using the ALD method... x membrane, GaO x membrane, ZnO x The membrane formation process is basically the same.

[0108] First, regarding InO x The formation of the membrane will be explained.

[0109] As described above, with Ar gas continuously supplied, valve 93 is opened, and In raw material gas is supplied from In raw material gas supply source 53 to the processing space S in chamber 1 via In raw material gas supply line 63 (step S1). The In raw material gas is generated by vaporizing triethylindium, which is an organic In precursor. Through step S1, the In raw material gas is adsorbed onto the surface of substrate W. At this time, the In raw material gas is temporarily stored in buffer tank 83 and supplied to chamber 1 after pressurization.

[0110] Next, valve 93 is closed to stop the In raw material gas, and the processing space S of chamber 1 is purged using continuously supplied Ar gas (step S2).

[0111] Next, valve 97 is opened, and O3 gas is supplied from O3 gas supply source 57 to the processing space S in chamber 1 via O3 gas supply line 67 (step S3). As a result, the In raw material gas adsorbed on the substrate reacts with the O3 gas. The O3 gas is temporarily stored in buffer tank 85 and then supplied to chamber 1 after pressurization.

[0112] Next, valve 97 is closed to stop the O3 gas, and Ar gas, which is continuously supplied as backflushing purging gas, is used to purge the processing space S of chamber 1 (step S4).

[0113] By successively performing the above steps S1 to S4, a thin InO layer is formed. x A unit membrane is formed by repeating these steps for a pre-defined X cycles to create an InO film of the desired thickness. x membrane.

[0114] Next, regarding GaO x The formation of the membrane will be explained.

[0115] Similarly, with Ar gas continuously supplied, valve 91 is opened, and Ga raw material gas is supplied from Ga raw material gas supply source 51 to the processing space S in chamber 1 via Ga raw material gas supply line 61 (step S1). The Ga raw material gas is generated by vaporizing triethylgallium, which is an organic Ga precursor. Through step S1, the Ga raw material gas is adsorbed onto the surface of substrate W. At this time, the Ga raw material gas is temporarily stored in buffer tank 81 and supplied to chamber 1 after pressurization.

[0116] Simultaneously with step S1, valve 96 is opened, and H2 gas is supplied from H2 gas supply source 56 to the processing space S in chamber 1 via H2 gas supply line 66 (step S5). At this time, H2 gas is temporarily stored in buffer tank 85 and supplied to chamber 1 after pressurization.

[0117] By performing steps S1 and S5 simultaneously, the thermal decomposition of organic Ga precursors, such as triethylgallium, can be promoted, thereby lowering the film formation temperature.

[0118] After steps S1 and S5, valve 91 is closed to stop the Ga feed gas, and valve 96 is closed to stop the H2 gas. The processing space S in chamber 1 is then purged (step S2). In step S2, the purging is intensified to minimize mixing of residual H2 gas in chamber 1 with the subsequently supplied O3 gas. Specifically, in addition to the continuously supplied Ar gas, valves 94a, 95a, and 98a are opened to supply Ar gas (purging Ar gas) from the first rapid purging line 64a, the second rapid purging line 65a, and the third rapid purging line 68a, increasing the purging gas flow rate. Furthermore, by increasing the opening of the automatic pressure control valve (APC) 47a and increasing the gap between the base 2 and the spray head 3 using the lifting mechanism 34, the pressure in chamber 1 is reduced only during step S2. Because steps S1 to S4 in the ALD are short, high-speed APC control and high-speed gap control are required to reduce the pressure in step S2.

[0119] Next, close valves 94a, 95a, and 98a, and open valve 97 to connect with InO. xSimilarly, during membrane formation, O3 gas is supplied from O3 gas supply source 57 to the processing space S in chamber 1 via O3 gas supply line 67 (step S3). As a result, the Ga raw material gas adsorbed on the substrate reacts with the O3 gas.

[0120] Next, valve 97 is closed to stop the O3 gas, and the processing space S of chamber 1 is purged using continuously supplied Ar gas (step S4).

[0121] Steps S1 to S4 are performed sequentially as described above, with step S5 performed in between, thereby forming a thin GaO film. x A unit film is formed by repeating these cycles for a pre-defined Y number of cycles to create a GaO film of the desired thickness. x membrane.

[0122] Next, regarding ZnO x The membrane formation process will be explained. Similarly, with Ar gas continuously supplied, valve 92 is opened, and Zn feed gas is supplied from Zn feed gas supply source 52 to the processing space S within chamber 1 via Zn feed gas supply line 62 (step S1). The Zn feed gas is generated by vaporizing diethylzinc, which is an organic Zn precursor. Through step S1, the Zn feed gas is adsorbed onto the surface of the substrate W. At this time, the Zn feed gas is temporarily stored in buffer tank 82 and then supplied to chamber 1 after pressurization.

[0123] Next, valve 92 is closed to stop the Zn raw material gas, and the processing space S of chamber 1 is purged using continuously supplied Ar gas (step S2).

[0124] Next, open valve 97, and connect it with InO. x Similarly, during membrane formation, O3 gas is supplied from O3 gas supply source 57 to the processing space S within chamber 1 via O3 gas supply line 67 (step S3). As a result, the Zn raw material gas adsorbed on the substrate reacts with the O3 gas.

[0125] Next, valve 97 is closed to stop the O3 gas, and the processing space S of chamber 1 is purged using continuously supplied Ar gas (step S4).

[0126] By successively performing the above steps S1 to S4, a thin ZnO layer is formed. x A unit membrane is formed by repeating these steps for a pre-defined number of Z cycles to create a ZnO membrane of the desired thickness. x membrane.

[0127] InO, N cycles are performed on substrate W. x membrane, GaO x membrane, ZnO xAfter the IGZO membrane is formed, the chamber 1 is purged with Ar gas, causing the substrate 2 to descend to the transport position. Then, the gate G is opened, and the substrate W on the substrate 2 is discharged from the chamber 1 using a transport device inserted from the vacuum transport chamber.

[0128] The above is through Figure 6 The example shown illustrates the sequence for forming an IGZO film, but it can also be achieved through... Figure 7 , Figure 8 The IGZO film is formed in the sequence shown.

[0129] <Other Applications>

[0130] The embodiments have been described above, but it should be considered that the embodiments disclosed herein are illustrative and not restrictive in all respects. The above embodiments may be omitted, substituted, or modified in various ways without departing from the appended claims (the scope of the invention) and its spirit.

[0131] For example, Figure 14 The film-forming apparatus shown is merely an example and may also be the same as... Figure 14 Different monolithic film deposition apparatuses can be used, as well as batch film deposition apparatuses that can deposit films on multiple substrates at once. Furthermore, an example of a film deposition apparatus for forming an IGZO film as a multi-element metal oxide film has been described, but it is not limited to this; for example, individual metal oxide films can also be formed.

Claims

1. A film forming method for forming a multi-metal oxide film on a substrate in a processing vessel, wherein, The multi-metal oxide film is composed of a plurality of metal oxide films each containing a different metal, and the film forming method is characterized in that: The film forming method has a plurality of stages in which the plurality of metal oxide films are formed respectively, Each of the stages includes: a step of supplying a raw material gas containing an organic metal precursor into the processing vessel; a step of removing a residual gas remaining in the processing vessel after the step of supplying the raw material gas; a step of supplying an oxidizing agent that oxidizes the raw material gas into the processing vessel, which is performed subsequently; and a step of removing a residual gas remaining in the processing vessel after the step of supplying the oxidizing agent, At least one of the plurality of stages includes a step of supplying a hydrogen-containing reducing gas into the processing vessel simultaneously with the step of supplying the raw material gas, thereby promoting thermal decomposition of the organic metal precursor, thereby making the optimum film forming temperature uniform, the optimum film forming temperature being a film forming temperature at which the film forming rate is constant due to saturation adsorption of the precursor in each of the plurality of stages.

2. The film forming method according to claim 1, characterized in that: The stage of the plurality of stages that has the step of supplying the hydrogen-containing reducing gas repeats the following steps for a plurality of cycles and performs the step of supplying the hydrogen-containing reducing gas in each cycle: the step of supplying the raw material gas; the step of removing the residual gas after the step of supplying the raw material gas; the step of supplying the oxidizing agent; and the step of removing the residual gas after the step of supplying the oxidizing agent.

3. The film forming method according to claim 1 or 2, characterized in that: The plurality of stages are repeated for a plurality of cycles.

4. The film forming method according to claim 1 or 2, characterized in that: The plurality of metal oxide films is InO x film, GaO x film, ZnO x film, the multi-component metal oxide film is an InGaZnO film.

5. The film forming method according to claim 4, characterized in that: forming the GaO x The stage of the film has a step of supplying a hydrogen-containing reducing gas, which is performed concurrently with the step of supplying the raw material gas.

6. The film forming method according to claim 4, characterized in that: forming the GaO x the stage of the film and forming the InO x The stage of the film has a step of supplying a hydrogen-containing reducing gas, and the step of supplying the hydrogen-containing reducing gas is performed simultaneously with the step of supplying the raw material gas.

7. The film forming method according to claim 6, characterized in that: In the case of forming the GaO film x In the case of forming the InO film x The amount of the hydrogen-containing reducing gas supplied in the step of supplying the hydrogen-containing reducing gas is smaller than in the case of forming the InO film 8. The film forming method according to claim 1, characterized in that: The step of removing the residual gas after the step of supplying the raw material gas also removes a residual gas remaining after the step of supplying the hydrogen-containing reducing gas.

9. The film forming method according to claim 8, characterized in that: A continuous purge gas that flows continuously is supplied into the processing vessel during the period in which the step of supplying the raw material gas, the step of removing the residual gas after the step of supplying the raw material gas, the step of supplying the oxidizing agent, and the step of removing the residual gas after the step of supplying the oxidizing agent are performed, The steps of removing the residual gas after the step of supplying the raw material gas and the step of removing the residual gas after the step of supplying the oxidizing agent are performed using the continuous purge gas, An additional purge gas is supplied in addition to the continuous purge gas at the step of removing the residual gas after the step of supplying the raw material gas.

10. The film forming method according to claim 9, characterized in that: The pressure in the processing vessel is reduced at the step of removing the residual gas after the step of supplying the raw material gas.

11. The film forming method according to claim 1, characterized in that: The step of supplying the hydrogen-containing reducing gas causes the organic ligand of the organic metal precursor to be removed.

12. The film forming method according to claim 1, wherein: the organic ligand of the organic metal precursor is an alkyl group, The step of supplying the hydrogen-containing reducing gas causes the alkyl group to be removed from the organic metal precursor adsorbed to the substrate to become a hydrogen-terminated group, and generation of H2O is suppressed in the step of supplying the oxidizing agent.

13. The film forming method according to claim 1, wherein: the hydrogen-containing reducing gas is hydrogen gas.

14. A film forming apparatus for forming a multi-metal oxide film on a substrate, comprising: the multi-metal oxide film is composed of a plurality of metal oxide films each containing a different metal, the film forming apparatus includes: a process container in which the substrate is accommodated; a substrate mounting table on which the substrate is mounted in the process container; a gas supply unit which supplies a gas to the process container; an exhaust unit which exhausts the process container; and a control unit, the control unit controls the gas supply unit and the exhaust unit so that the following steps are performed: a step of supplying a raw material gas containing an organic metal precursor into the process container; a step of removing a residual gas remaining in the process container after the step of supplying the raw material gas; a step of supplying an oxidizing agent which oxidizes the raw material gas into the process container, which is performed subsequently; a step of removing a residual gas remaining in the process container after the step of supplying the oxidizing agent; and a step of supplying a hydrogen-containing reducing gas into the process container simultaneously with the step of supplying the raw material gas, thereby promoting thermal decomposition of the organic metal precursor, thereby making the optimum film forming temperature uniform, the optimum film forming temperature being a film forming temperature at which a film forming rate is constant due to saturation adsorption of a precursor in each of a plurality of stages in which the plurality of metal oxide films are formed, respectively.

Images