Thin film deposition method and thin film deposition apparatus

Abstract

To provide a film deposition method and a film deposition apparatus capable of depositing a metal oxide film with less impurity.SOLUTION: A film deposition method for depositing a metal oxide film on a substrate in a treatment container has the steps of: supplying a raw material gas containing an organic metal precursor into the treatment container; removing a residual gas remaining in the treatment container after the step of supplying the raw material gas; consecutively supplying an oxidizer for oxidizing the raw material gas into the treatment container; removing a residual gas remaining in the treatment container after the step of supplying the oxidizer; and supplying a reduction gas containing hydrogen into the treatment container simultaneously with the step of supplying the raw material gas or sequentially after the step of supplying the raw material gas.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a film forming method and a film forming apparatus.

Background Art

[0002] As a method for forming a metal oxide film, an atomic layer deposition method (ALD method) in which an organometallic precursor and an oxidizing agent are alternately supplied is known. Patent Document 1 describes that when forming a multi-metal oxide film such as IGZO by the ALD method, individual metal oxide films are formed in order, and further, by changing the frequency of the formation step of a specific metal oxide film, the content ratio in the film thickness direction of the multi-metal oxide film can be changed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a film forming method and a film forming apparatus capable of forming a metal oxide film with less impurities.

Means for Solving the Problems

[0005] A film deposition method according to one embodiment of the present disclosure is a film deposition method for depositing a metal oxide film on a substrate in a processing container, comprising the steps of: supplying a raw material gas containing an organometallic precursor in which an organic ligand is bonded to a metal element of the metal oxide film to be deposited into the processing container; removing residual gas remaining in the processing container after the step of supplying the raw material gas; subsequently, supplying an oxidizing agent to oxidize the raw material gas into the processing container; removing residual gas remaining in the processing container after the step of supplying the oxidizing agent; and supplying a reducing gas containing hydrogen into the processing container simultaneously with the step of supplying the raw material gas. It is a step to do , By supplying the aforementioned reducing gas The method comprises the steps of: 1) removing the organic ligand and 2) promoting the thermal decomposition of the organometallic precursor to lower the film deposition temperature. [Effects of the Invention]

[0006] This disclosure provides a film deposition method and apparatus capable of forming a metal oxide film with few impurities. [Brief explanation of the drawing]

[0007] [Figure 1] This is a timing chart showing the gas supply timing in an example of a film deposition method according to the first embodiment. [Figure 2] This is a timing chart showing the gas supply timing in another example of the film deposition method according to the first embodiment. [Figure 3] This diagram illustrates the effect of reducing impurities when H2 gas is supplied. [Figure 4] This diagram illustrates the effect of reducing H2O generation when H2 gas is supplied. [Figure 5] This is a timing chart showing the gas supply timing in yet another example of the film deposition method according to the first embodiment. [Figure 6] This is a timing chart showing the gas supply timing in an example of a film deposition method according to the second embodiment. [Figure 7]This is a timing chart showing the gas supply timing in another example of the film deposition method according to the second embodiment. [Figure 8] This is a timing chart showing the gas supply timing in yet another example of the film deposition method according to the second embodiment. [Figure 9] This is a schematic cross-sectional view showing an IGZO film, which is a specific example of the multi-metal oxide film to be deposited in the second embodiment. [Figure 10] This figure shows the relationship between substrate temperature and film thickness, and the relationship between substrate temperature and impurity concentration, when depositing an InOx film using the conventional ALD method. [Figure 11] This figure shows the relationship between substrate temperature and film thickness, and the relationship between substrate temperature and impurity concentration, when depositing a GaOx film using the conventional ALD method. [Figure 12] This figure shows the relationship between substrate temperature and film thickness, and the relationship between substrate temperature and impurity concentration, when depositing a ZnOx film using the conventional ALD method. [Figure 13] This figure shows the reduction in the ALD window temperature range when triethylgallium and H2 gas are supplied simultaneously during GaOx film deposition. [Figure 14] This is a cross-sectional view showing an example of a film deposition apparatus used in a film deposition method. [Modes for carrying out the invention]

[0008] The embodiments will be described below with reference to the attached drawings.

[0009] <Film formation method> First, an embodiment of the film deposition method will be described.

[0010] [First Embodiment] In this embodiment, a metal oxide film is formed by the ALD method while the substrate is housed in a processing container.

[0011] FIG. 1 is a timing chart showing the gas supply timing in an example of a film formation method according to the first embodiment. As shown in FIG. 1, the film formation method according to the first embodiment includes step S1, step S2, step S3, step S4, and step S5. Then, the sequence of steps S1 to S4 is repeated for a desired cycle, and step S5 is performed in each cycle.

[0012] Step S1 is a step of supplying a source gas (MO gas) containing an organometallic precursor into the processing vessel. The MO gas is generated, for example, by vaporizing a liquid or solid organometallic precursor. Step S2 is a step of purging the inside of the processing vessel after performing step S1 to discharge the gas remaining in the processing vessel. Step S3 is a step of supplying an oxidant into the processing vessel after step S2. Step S4 is a step of purging the inside of the processing vessel after performing step S3 to discharge the gas remaining in the processing vessel. Step S5 is a step of supplying a reducing gas containing hydrogen, for example, hydrogen gas (H2 gas), into the processing vessel. In the example of FIG. 1, an example is shown in which the supply of the reducing gas containing hydrogen in step S5 is performed simultaneously with the supply of the MO gas in step S1. In the example of FIG. 1, a case where the supply period of the organometallic precursor and the supply period of the reducing gas containing hydrogen completely coincide is shown, but "simultaneously" also includes a case where a part of these periods coincide.

[0013] FIG. 2 is a timing chart showing the gas supply timing in another example of the film formation method according to the first embodiment. This example shows an example in which step S5 is performed sequentially after step S1. Steps S1 to S4 are the same as those in the example of FIG. 1.

[0014] Hereinafter, the sequences of FIGS. 1 and 2 will be described in more detail. In step S1, by supplying the MO gas into the processing vessel, the MO gas is adsorbed on the surface of the substrate. In the ALD method, a temperature range (ALD window) in which the film formation rate (film thickness) is constant is used so as to achieve saturated adsorption.

[0015] The organometallic precursor used in step S1 is a metal oxide film to which an organic ligand is bonded. 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 and C2H5. Other organic ligands include amino groups. Alkoxy group Carbonyl groups and the like can also be used.

[0016] In step S3, an oxidizing agent is supplied into the processing container to oxidize the MO gas adsorbed on the substrate surface, forming a metal oxide film. The oxidizing agent used in step S3 can be any agent that reacts with MO gas to form a metal oxide, such as ozone (O3) gas, oxygen (O2) gas, or water vapor (H2O) gas.

[0017] The purging in steps S2 and S4 may be performed by evacuating the processing vessel, by supplying a purge gas into the processing vessel to discharge residual gas, or by doing both. As the purge gas, a noble gas such as Ar gas or an inert gas such as N2 gas can be used. In the examples in Figures 1 and 2, an example is shown in which purging is performed by continuously supplying the purge gas as a counter gas.

[0018] In step S5, in addition to H2 gas, other hydrogen-containing reducing gases such as NH3 and alcohols such as ethanol (C2H5OH) can be used. In step S5, both the sequence in Figure 1 and the sequence in Figure 2 involve supplying a hydrogen-containing reducing gas, such as H2 gas. This gas reacts with the organic ligand in the organometallic precursor, causing the organic ligand to be removed and reducing impurities in the film. Figure 3 shows an example using triethylindium as the organometallic precursor, O3 gas as the oxidizing agent, and H2 gas as the hydrogen-containing reducing gas. If O3 gas is supplied in step S3 without supplying H2 gas after adsorbing triethylindium onto the substrate in step S1, the ethyl group (C2H5-), which is an organic ligand, is more likely to remain as an impurity, as shown in Figure 3(a). In contrast, by going through step S5, which involves supplying H2 gas, the ethyl group is removed from the adsorbed triethylindium, as shown in Figure 3(b), and that portion is hydrogen-terminated, thus reducing the generation of impurities in the subsequent oxidation step with O3 gas.

[0019] Furthermore, when the organic ligand of the organometallic precursor is an alkyl group, the CHx-terminal surface changes to an H-terminal surface through the step of supplying a reducing gas containing hydrogen, which improves the reactivity with the oxidizing agent and allows the oxidation reaction to proceed in a short time.

[0020] Furthermore, supplying an oxidizing agent to the CHx-terminated surface generates a large amount of water (H2O), which prolongs purging time. Additionally, during purging, H2O may be re-adsorbed onto, for example, the walls of holes formed in the substrate, potentially leading to a non-uniform surface reaction and uneven film thickness. In contrast, supplying a hydrogen-containing reducing gas to make the substrate surface an H-terminated surface reduces the generation of H2O after oxidizing agent supply, thus resolving the aforementioned problems. For example, when O3 gas is supplied without supplying a hydrogen-containing reducing gas while triethylindium is vaporized and adsorbed, 5 H2O molecules are generated per molecule, as shown in Figure 4(a). In contrast, when H2 gas is supplied as a hydrogen-containing reducing gas while triethyleneindium is adsorbed, and then O3 gas is supplied, only 1 H2O molecule is generated per molecule, as shown in Figure 4(b).

[0021] When a reducing gas containing hydrogen is supplied simultaneously with the MO gas, it is possible to further accelerate the thermal decomposition of the organometallic precursor and lower the film deposition temperature.

[0022] Next, we will describe yet another example of the first embodiment. Figure 5 is a timing chart showing the gas supply timing in yet another example of the film deposition method according to the first embodiment. This example shows a method that can reliably prevent mixing of a reducing gas containing hydrogen, such as H2 gas, with an oxidizing agent. If an oxidizing agent such as O3 gas is supplied while, for example, H2 gas remains in the processing container, an explosive reaction may occur. Therefore, in this example, the purging in step S2 is strengthened to prevent these reactions as much as possible. For example, this can be done by increasing the flow rate of the purge gas in step S2 and / or strengthening the exhaust during step S2. In the example in Figure 5, the purge gas is constantly flowing as a counter gas, and in step S2, additional purge gas is flowed from another line to increase the flow rate of the purge gas, and the pressure is reduced only during the period of step S2. In the case of film deposition by the ALD method, each step is short in duration, so the pressure reduction must be performed at high speed, and the strengthening of the exhaust can be done, for example, by high-speed APC opening control or high-speed gap control, as will be described later.

[0023] [Second Embodiment] Next, a second embodiment will be described. In this embodiment, a multi-component metal oxide film consisting of multiple metal oxide films, each containing a different metal, is basically formed by the ALD method with the substrate housed in a processing container. Taking a ternary alloy oxide film as an example, there is a first step of forming a first metal oxide film by ALD, a second step of forming a second metal oxide film by ALD, and a third step of forming a third metal oxide film by ALD. Each step basically includes the same steps as in the first embodiment: supplying MO gas, purging residual gas, supplying an oxidizing agent to the substrate, and purging residual gas. These steps are repeated for a desired number of cycles in each step, and then the first to third steps are repeated for a desired number of cycles. In addition, at least one of the first, second, and third steps includes a step of supplying a reducing gas containing hydrogen to the substrate simultaneously with the step of supplying MO gas in each cycle.

[0024] Figure 6 is a timing chart showing the gas supply timing in an example of a film deposition method according to the second embodiment. The example in Figure 6 shows the deposition of a ternary metal oxide film.

[0025] As shown in Figure 6, the process has 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 steps S1 to S4 similar to those in the first embodiment, and 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, steps 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 the MO gas in step S1 is performed simultaneously with the supply of the reducing gas containing hydrogen in step S5.

[0026] Furthermore, Figure 7 shows an example in which step S5 is performed in the first stage (ST1) and the second stage (ST2), and Figure 8 shows an example in which step S5 is performed in all stages from the first stage (ST1) to the third stage (ST3). In these cases, as shown in Figures 7 and 8, the amount of reducing gas containing hydrogen supplied may be different in each stage.

[0027] In this embodiment as well, by supplying a reducing gas containing hydrogen, the effects of reducing impurities, improving reactivity with the oxidizing agent due to the change from a CHx-terminated surface to an H-terminated surface, and suppressing the amount of H2O generated can be obtained, similar to the first embodiment. These effects can be obtained not only when the organometallic precursor and the reducing gas containing hydrogen are supplied simultaneously, but also when they are supplied sequentially, as in the example in Figure 2 of the first embodiment.

[0028] Furthermore, as described above, by performing the step of supplying a reducing gas containing hydrogen to the substrate at the same time as the step of supplying the organometallic precursor, the effect of promoting the thermal decomposition of the organometallic precursor and lowering the film deposition temperature can also be obtained. In this embodiment, by utilizing this effect of lowering the film deposition temperature, the film deposition temperatures of each metal oxide film can be made uniform when depositing a multi-component metal oxide film by the ALD method, as will be explained below.

[0029] When depositing a multi-component metal oxide film, such as in this embodiment, by the ALD method, it is desirable to perform the process in the same processing vessel and at the same temperature from the viewpoint of cycle time. On the other hand, in the ALD method, the optimal deposition temperature is the temperature range (ALD window) in which the precursor is saturated adsorbed and the deposition rate (film thickness) becomes constant, and the impurity concentration also decreases at this temperature. However, since the ALD window depends greatly on the precursor used, the optimal deposition temperature for each metal oxide film constituting the multi-component metal oxide film may differ. For this reason, in this embodiment, in at least one of the first, second, and third stages, in each cycle, the step of supplying MO gas and the step of supplying a reducing gas containing hydrogen to the substrate are performed simultaneously to promote the thermal decomposition of the organometallic precursor and lower the deposition temperature. Therefore, by supplying a reducing gas containing hydrogen simultaneously with MO gas to lower the deposition temperature when depositing a metal oxide film with a high ALD window temperature range, it becomes possible to appropriately perform ALD deposition of multi-component metal oxide films at the same temperature. As in the first embodiment, "simultaneous" also includes cases where the supply period of the organometallic precursor and the supply period of the reducing gas containing hydrogen partially coincide.

[0030] Next, a specific example of the second embodiment will be described. Here, we will explain using an InGaZnO film (IGZO film), an oxide semiconductor thin film composed of InOx, GaOx, and ZnOx, as an example of a multi-metal oxide film. For example, if the first metal oxide film is InOx, the second metal oxide film is GaOx, and the third metal oxide film is ZnOx, the IGZO film is deposited by the ALD method as shown in Figure 9. That is, steps S1 to S4 above are repeated for X, Y, and Z cycles, respectively, to deposit a laminated film of InOx film 201, GaOx film 202, and ZnOx film 203 on a substrate 200 on which an oxide film (SiO2 film) has been formed on the surface. Then, this deposition of the laminated film is considered one cycle, and this is repeated for N cycles to deposit an IGZO film of the desired thickness. As organometallic precursors, for example, triethylindium, triethylgallium, and diethylzinc can be used.

[0031] Figures 10-12 show the relationship between substrate temperature and film thickness, and the relationship between substrate temperature and impurity concentration, respectively, when depositing InOx, GaOx, and ZnOx films using the conventional ALD method. The substrate temperature is shown as the temperature of the stage on which the substrate is placed. The impurity concentration is shown as the concentration of hydrogen (H) and carbon (C). Here, triethylindium, triethylgallium, and diethylzinc are used as organometallic precursors, specifically organic In, organic Ga, and organic Zn precursors, and O3 gas is used as the oxidizing agent. As mentioned above, the ALD window, which is the temperature range where the film deposition rate is constant and the impurity concentration is low, is the optimal film deposition temperature for ALD. Since the film deposition rate is proportional to the film thickness, as shown in Figures 10-12, the temperature range of the ALD window is approximately 200-250°C for InOx films, approximately 250-300°C for GaOx films, and around 200°C for ZnOx films. Thus, because the optimal deposition temperatures for InOx, GaOx, and ZnOx films differ, achieving optimal deposition is difficult when depositing IGZO films at the same ALD temperature.

[0032] In contrast, for example, when depositing a GaOx film, which is the second oxide film, by simultaneously supplying a Ga raw material gas and a reducing gas containing hydrogen, such as H2 gas, as shown in Figure 6, the thermal decomposition of the organometallic precursor can be promoted during GaOx film deposition, thereby lowering the temperature range of the ALD window. This makes it possible to standardize the optimal deposition temperature of each metal oxide film during IGZO film deposition, and to deposit the IGZO film by optimal ALD deposition at the same temperature.

[0033] In addition to depositing the second oxide film, GaOx, simultaneously supplying In source gas and a hydrogen-containing reducing gas when depositing the first oxide film, InOx, can also lower the deposition temperature of the InOx film, which has a higher ALD window temperature range than the ZnOx film. In this case, by optimizing the amount of hydrogen-containing reducing gas used when depositing the InOx film (which can be deposited at a lower temperature than the GaOx film) to be less than the amount of hydrogen-containing reducing gas used when depositing the GaOx film, the IGZO film can be deposited under more suitable conditions.

[0034] Furthermore, a hydrogen-containing reducing gas may be supplied during the deposition of InOx, GaOx, and ZnOx films. This allows for impurity reduction and H2O reduction during the deposition of all metal oxide films, and also lowers the overall deposition temperature. By optimizing the amount of hydrogen-containing reducing gas used during the deposition of each metal oxide film, the optimal deposition temperature for each metal oxide film can be standardized, enabling the deposition of IGZO films by optimal ALD deposition at the same temperature.

[0035] The effect of reducing the film deposition temperature by hydrogen-containing reducing gases, as described above, can be verified by the activation energy. For example, when triethylgallium is used when depositing a GaOx film, 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 gas, the thermal decomposition of triethylgallium can be promoted, and as shown in Figure 13, the temperature range of the ALD window can be lowered, i.e., the film deposition temperature can be lowered. When triethylindium and diethylzinc are used, the activation energies for the dissociation of the ethyl group are +2.32 eV and 2.07 eV, respectively, and it can be seen that the ease of thermal decomposition is Zn (diethylzinc) > In (triethylindium) > Ga (triethylgallium). Furthermore, the activation energies for the reaction of triethylindium and diethylzinc with hydrogen are +1.56 eV and 1.82 eV, respectively, indicating that the thermal decomposition of these can also be accelerated by a reducing gas containing hydrogen, such as H2 gas.

[0036] In this example, it is natural that by performing the step of supplying a reducing gas containing hydrogen when depositing at least one of the InOx, GaOx, and ZnOx films, the basic effects such as the reduction of impurities as described above can be obtained.

[0037] <Film forming equipment> Next, an example of a film deposition apparatus capable of implementing the above-described embodiment of the film deposition method will be explained. Figure 14 is a cross-sectional view showing an example of a film deposition apparatus. Here, an example of a film deposition apparatus that deposits an IGZO film using an organic Ga precursor, an organic Zn precursor, and an organic In precursor as organometallic precursors, O3 gas as an oxidizing agent, Ar gas as a purge gas, and H2 gas as a hydrogen-containing reducing gas is shown.

[0038] The film deposition apparatus 100 includes a chamber 1 which is a processing container, a susceptor (mounting platform) 2, a shower head 3, an exhaust unit 4, a processing gas supply mechanism 5, and a control unit 6.

[0039] The processing container, chamber 1, is made of a roughly cylindrical metal. An inlet / outlet 26 is formed in the side wall of chamber 1 for loading and unloading substrates W to and from a vacuum transport chamber (not shown) by a transport mechanism (not shown), and the inlet / outlet 26 can be opened and closed by a gate valve G.

[0040] An annular exhaust duct 28 with a rectangular cross-section is provided on top of the main body of the chamber 1. A slit 28a is formed along the inner circumference of the exhaust duct 28. An exhaust port 28b is formed on the outer wall of the exhaust duct 28. A top wall 29 is provided on the upper surface of the exhaust duct 28 so as to close the upper opening of the chamber 1. The space between the top wall 29 and the exhaust duct 28 is airtightly sealed with a seal ring 30.

[0041] The susceptor 2, which is a mounting platform, is used to place the substrate W within the chamber 1. The susceptor 2 is disc-shaped, corresponding to the size of the substrate W, and is mounted horizontally. The susceptor 2 is supported by a support member 33. A heater 31 for heating the substrate W is embedded inside the susceptor 2. The heater 31 is powered by a heater power supply (not shown) and generates heat. By controlling the output of the heater 31, the substrate W can be controlled to a desired temperature. The susceptor 2 is provided with a ceramic cover member 32 that covers the outer periphery of the substrate mounting surface and the sides.

[0042] The support member 33 that supports the susceptor 2 extends downward from the center of the bottom surface of the susceptor 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 lifting mechanism 34 allows the susceptor 2 to move up and down via the support member 33 between the processing position shown by the solid line in Figure 14 and the transport position shown by the dashed line below it, where substrate transport is possible. The lifting mechanism 34 can also move up and down at high speed during purging. A flange portion 35 is attached to the lower part of the support member 33 below the chamber 1, and a bellows 36 is provided between the bottom surface of the chamber 1 and the flange portion 35, which partitions the atmosphere inside the chamber 1 from the outside air and expands and contracts in accordance with the lifting operation of the susceptor 2.

[0043] Near the bottom of the chamber 1, three support pins (only two are shown) are provided, protruding upward from the lifting plate 37a. The support pins 37 can be raised and lowered via the lifting plate 37a by a lifting mechanism 38 located below the chamber 1, and are inserted into through holes 22 provided in the susceptor 2 at the transport position, allowing them to protrude and retract relative to the upper surface of the susceptor 2. This enables the transfer of the substrate W between the substrate transport mechanism (not shown) and the susceptor 2.

[0044] The shower head 3 is for supplying the processed gas into the chamber 1 in a shower-like manner. It is installed at the top of the chamber 1, facing the susceptor 2, and has approximately the same diameter as the susceptor 2. The shower head 3 has a main body 39 fixed to the top wall 29 of the chamber 1, and a shower plate 40 connected below the main body 39. A gas diffusion space 41 is formed between the main body 39 and the shower plate 40.

[0045] Multiple gas dispersing members 42 are provided within the gas diffusion space 41. Multiple gas discharge holes are formed around the gas dispersing members 42. The gas dispersing members 42 are connected to one end of each of the multiple gas supply passages 43 provided in the main body 39. The other end of the gas supply passage 43 is connected to a diffusion section 44 formed in the center of the upper surface of the main body 39. In addition, a gas introduction hole 45 is provided in the center of the main body 39, penetrating from its upper surface to the diffusion section 44.

[0046] An annular projection 40b is formed on the periphery of the shower plate 40, projecting downward, and a gas discharge hole 40a is formed on the flat surface inside the annular projection 40b of the shower plate 40. When the susceptor 2 is in the processing position, a processing space S is formed between the shower plate 40 and the susceptor 2, and the annular projection 40b and the upper surface of the cover member 32 of the susceptor 2 come into close proximity to form an annular gap 48.

[0047] The exhaust unit 4 includes an exhaust pipe 46 connected to the exhaust port 28b of the exhaust duct 28, an exhaust mechanism 47 having a vacuum pump connected to the exhaust pipe 46, and an automatic pressure control valve (APC) 47a provided on the exhaust pipe. During processing, the gas in the chamber 1 reaches the exhaust duct 28 through the slit 28a, and is exhausted from the exhaust duct 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 is controlled by the opening degree of the automatic pressure control valve (APC) 47a.

[0048] The processing gas supply mechanism 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 ozonizer. 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 a purge gas.

[0049] 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 each connected to one end of the Ga raw material gas supply line 61, Zn raw material gas supply line 62, In raw material gas supply line 63, H2 gas supply line 66, and O3 gas supply line 67, respectively.

[0050] The first Ar gas supply source 54, the second Ar gas supply source 55, and the third Ar gas supply source 58 are 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, respectively. 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 are constantly supplied with Ar gas as a counter-purge gas during processing.

[0051] The other end of the Ga raw material gas supply line 61 is connected to the Zn raw material gas supply line 62, and the other end of the first continuous Ar gas supply line 64 is connected to the Zn raw material gas supply line 62 via the Ga raw material gas supply line 61. The other end of the second continuous Ar gas supply line 65 is connected to the In raw material gas supply line 63. The other end of the H2 gas supply line 66 is connected to the 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 the O3 gas supply line 67. The other ends of the Zn raw material gas supply line 62, the In raw material gas supply line 63, and the O3 gas supply line 67 merge into a confluence line 69, which is connected to the gas introduction hole 45.

[0052] The first flash purge line 64a branches off from the first continuous Ar gas supply line 64, the second flash purge line 65a branches off from the second continuous Ar gas supply line 65, and the third flash purge line 68a branches off from the third continuous Ar gas supply line 68. The lower ends of the first flash purge line 64a, the second flash purge line 65a, and the third flash purge line 68a merge into 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 flash purge line 64a, the second flash purge line 65a, and the third flash purge line 68a are lines for supplying a large amount of Ar gas during purging to perform flash purging.

[0053] The Ga raw material gas supply line 61 is equipped with a flow meter 71, a buffer tank 81, and a valve 91 from the upstream side. The Zn raw material gas supply line 62 is equipped with a flow meter 72, a buffer tank 82, and a valve 92 from the upstream side. The In raw material gas supply line 63 is equipped with a flow meter 73, a buffer tank 83, and a valve 93 from the upstream side. The H2 gas supply line 66 is equipped with a flow controller 76, a buffer tank 84, and a valve 96 from the upstream side. The O3 gas supply line 67 is equipped with a flow controller 77, a buffer tank 85, and a valve 97 from the upstream side. Buffer tanks 81 to 85 are for temporarily storing each gas, and by storing the gas in them, increasing the pressure inside, and then supplying the stored gas, a large flow rate of gas can be supplied into the chamber 1.

[0054] The first Ar gas supply source 54, the second Ar gas supply source 55, and the third Ar gas supply source 58 are each fitted with a flow controller 74 and valve 94, a flow controller 75 and valve 95, and a flow controller 78 and valve 98, respectively, from the upstream side. In addition, the first flash purge line 64a, the second flash purge line 65a, and the third flash purge line 68a are each fitted with a flow controller 74a and valve 94a, a flow controller 75a and valve 95a, and a flow controller 78a and valve 98a, respectively, from the upstream side.

[0055] Valves 91, 92, 93, 96, 97, 94a, 95a, and 98a function as ALD valves for switching gases during ALD and consist of high-speed valves that can be opened and closed at high speed.

[0056] Triethylgallium, diethylzinc, and triethylindium, used as organic Ga precursors, organic Zn precursors, and organic In precursors, are liquids at room temperature. Therefore, the Ga raw material gas supply source 51, Zn raw material gas supply source 52, and In raw material gas supply source 53 have a mechanism for vaporizing the liquid raw materials. For example, the Ga raw material gas supply source has a raw material container for storing the liquid organic Ga precursor, a heating mechanism for heating the raw material container, and a carrier gas supply line for supplying carrier gas into the raw material container. The Ga raw material gas supply line 61 is inserted into the raw material container, and the Ga raw material gas is transported through the raw material gas supply line 61 by the carrier gas. The flow rate of the Ga raw material is controlled by a flow rate controller installed in the carrier gas supply line. The Zn raw material gas supply source 52 and the In raw material gas supply source 53 are configured similarly.

[0057] Note that the first to third flash purge lines 64a, 65a, and 68a, and buffer tanks 81 to 85 are not mandatory.

[0058] The control unit 6 is composed of a computer and includes a main control unit equipped with a CPU, an input device, an output device, a display device, and a storage device (storage medium). The main control unit controls, for example, the opening and closing of valves, the gas flow rate controlled by a flow controller, the opening degree of a pressure control valve (APC), and the output of a heater that heats the substrate W. These controls are executed according to processing recipes stored in a storage medium built into the storage device.

[0059] Next, an example of a film deposition procedure using the film deposition apparatus 100 configured as described above will be explained. The control unit 6 controls the heating by the heater 31 in advance so that the temperature of the substrate W placed on the susceptor 2 reaches a desired temperature, thereby controlling the temperature of the susceptor 2.

[0060] In that state, first, the gate valve G is opened and the substrate W is transported from the vacuum transport chamber into the chamber 1 by a transport device (neither of which is shown) and placed on the susceptor 2.

[0061] After placing the substrate W and retracting the transport device, the gate valve G is closed and the susceptor 2 is raised to the processing position. Next, the chamber 1 is evacuated by the exhaust unit 4, 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.

[0062] Then, while maintaining a continuous supply of Ar gas, InOx, GaOx, and ZnOx films are continuously deposited using the ALD method as shown below, and this deposition cycle is repeated N times. The deposition of InOx, GaOx, and ZnOx films using the ALD method is basically carried out using the same procedure.

[0063] First, let's explain how to deposit an InOx film. 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). In raw material gas is produced by vaporizing triethylindium, which is an organic In precursor. In step S1, the In raw material gas is adsorbed onto the surface of the substrate W. At this time, the In raw material gas is temporarily stored in buffer tank 83, pressurized, and then supplied into chamber 1.

[0064] Next, valve 93 is closed to stop the In raw material gas, and the processing space S of chamber 1 is purged with the continuously supplied Ar gas (step S2).

[0065] Next, valve 97 is opened, and O3 gas is supplied from the O3 gas supply source 57 to the processing space S in the chamber 1 via the O3 gas supply line 67 (step S3). This causes the In raw material gas adsorbed on the substrate to react with the O3 gas. The O3 gas is temporarily stored in the buffer tank 85, pressurized, and then supplied into the chamber 1.

[0066] Next, valve 97 is closed to stop the O3 gas, and the processing space S of chamber 1 is purged with Ar gas, which is continuously supplied as a counter-purge gas (step S4).

[0067] By performing the above steps S1 to S4 sequentially, a thin InOx unit film is formed, and by repeating the cycle of these steps for a predetermined X cycles, an InOx film of the desired thickness is deposited.

[0068] Next, we will explain the deposition of GaOx films. 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). Ga raw material gas is produced by vaporizing triethylgallium, which is an organic Ga precursor. In step S1, the Ga raw material gas is adsorbed onto the surface of the substrate W. At this time, the Ga raw material gas is temporarily stored in buffer tank 81, pressurized, and then supplied into chamber 1.

[0069] Simultaneously with step S1, valve 96 is opened, and H2 gas is supplied from the H2 gas supply source 56 to the processing space S in the chamber 1 via the H2 gas supply line 66 (step S5). At this time, the H2 gas is temporarily stored in the buffer tank 85, pressurized, and then supplied into the chamber 1.

[0070] By performing steps S1 and S5 simultaneously, the thermal decomposition of the organic Ga precursor, such as triethylgallium, is accelerated, allowing the film deposition temperature to be lowered.

[0071] After steps S1 and S5 are completed, valve 91 is closed to stop the Ga raw material gas, and valve 96 is closed to stop the H2 gas, purging the processing space S of chamber 1 (step S2). In step S2, the purging is intensified to minimize mixing of the H2 gas remaining in chamber 1 with the next supplied O3 gas. Specifically, in addition to the continuously supplied Ar gas, valves 94a, 95a, and 98a are opened to supply Ar gas (flash purge Ar gas) from the first flash purge line 64a, the second flash purge line 65a, and the third flash purge line 68a, increasing the purge gas flow rate. In addition, the pressure inside chamber 1 is reduced only during step S2 by increasing the opening of the automatic pressure control valve (APC) 47a and by increasing the gap between the susceptor 2 and the shower head 3 using the lifting mechanism 34. Since the time for steps S1 to S4 in ALD is short, high-speed APC control and high-speed gap control are necessary in step S2 to reduce the pressure.

[0072] Next, valves 94a, 95a, and 98a are closed, and valve 97 is opened to supply O3 gas from the O3 gas supply source 57 to the processing space S in the chamber 1 via the O3 gas supply line 67, similar to the process for depositing the InOx film (step S3). This causes the Ga raw material gas adsorbed on the substrate to react with the O3 gas.

[0073] Next, valve 97 is closed to stop the O3 gas flow, and the processing space S of chamber 1 is purged with the continuously supplied Ar gas (step S4).

[0074] As described above, steps S1 to S4 are performed sequentially, with step S5 being performed in between to form a thin GaOx unit film. By repeating these cycles for a predetermined number of Y cycles, a GaOx film of the desired thickness is deposited.

[0075] Next, we will explain the deposition of ZnOx films. Similarly, with Ar gas continuously supplied, valve 92 is opened, and Zn raw material gas is supplied from Zn raw material gas supply source 52 to the processing space S in chamber 1 via Zn raw material gas supply line 62 (step S1). The Zn raw material gas is produced by vaporizing diethylzinc, which is an organic Zn precursor. In step S1, the Zn raw material gas is adsorbed onto the surface of the substrate W. At this time, the Zn raw material gas is temporarily stored in buffer tank 82, pressurized, and then supplied into chamber 1.

[0076] Next, valve 92 is closed to stop the Zn raw material gas, and the processing space S of chamber 1 is purged with the continuously supplied Ar gas (step S2).

[0077] Next, valve 97 is opened, and O3 gas is supplied from the O3 gas supply source 57 to the processing space S in chamber 1 via the O3 gas supply line 67, similar to the process for depositing the InOx film (step S3). This causes the Zn raw material gas adsorbed on the substrate to react with the O3 gas.

[0078] Next, valve 97 is closed to stop the O3 gas flow, and the processing space S of chamber 1 is purged with the continuously supplied Ar gas (step S4).

[0079] By performing the above steps S1 to S4 sequentially, a thin ZnOx unit film is formed, and by repeating the cycle of these steps for a predetermined Z cycle, a ZnOx film of the desired thickness is deposited.

[0080] InOx film, GaO x After the deposition of the ZnOx film is completed by performing N cycles of film deposition, the chamber 1 is purged with Ar gas and the susceptor 2 is lowered to the transport position. Next, the gate valve G is opened and the substrate W on the susceptor 2 is discharged from the chamber 1 by a transport device inserted from the vacuum transport chamber.

[0081] The above is an example of depositing an IGZO film using the sequence shown in Figure 6, but the IGZO film may also be deposited using the sequences shown in Figures 7 and 8.

[0082] <Other applications> Although embodiments have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0083] For example, the film deposition apparatus shown in Figure 14 is merely illustrative, and the apparatus may be a multi-layer deposition apparatus with a different structure than that shown in Figure 14, or a batch-type deposition apparatus that deposits films on multiple substrates at once. Furthermore, although the example of a film deposition apparatus used to deposit an IGZO film, which is a multi-component metal oxide film, the apparatus is not limited to this, and for example, it may be used to deposit a single metal oxide film. [Explanation of symbols]

[0084] 1; Chamber 2; Susceptor 3; shower head 4; Exhaust section 5; Gas supply mechanism 6; Control Unit 51; Ga raw material gas supply source 52; Zn raw material gas supply source 53; In raw material gas supply source 54, 55, 58; Continuous Ar gas supply source 56; H2 gas supply source 57; O3 gas supply source 100; Film deposition equipment 200; substrate 201;InOx film 202;GaOx film 203;ZnOx film W; substrate

Claims

1. A method for forming a metal oxide film on a substrate inside a processing container, The process involves supplying a raw material gas containing an organometallic precursor in which an organic ligand is bonded to the metal element of the metal oxide film to be formed into the processing container, The step of supplying the raw material gas is followed by the step of removing the residual gas remaining in the processing container, The next step is to supply an oxidizing agent for oxidizing the raw material gas into the processing container, The step of supplying the oxidizing agent is followed by the step of removing residual gas remaining in the processing container, A step of supplying a reducing gas containing hydrogen into the processing container at the same time as supplying the raw material gas, wherein the supply of the reducing gas causes the organic ligand to be detached from the organometallic precursor and promotes the thermal decomposition of the organometallic precursor to lower the film deposition temperature, A film formation method having the following characteristics.

2. The film formation method according to claim 1, wherein the steps of supplying the raw material gas, removing the residual gas after the supply of the raw material gas, supplying the oxidizing agent, and removing the residual gas after the supply of the oxidizing agent are repeated multiple times, and in each cycle the step of supplying the reducing gas containing the hydrogen is performed.

3. A film deposition method for depositing a multi-component metal oxide film on a substrate in a processing container, the multi-component metal oxide film being composed of multiple metal oxide films each containing a different metal, The process comprises several steps for forming each of the aforementioned multiple metal oxide films. Each of the above steps is: The process involves supplying a raw material gas containing an organometallic precursor in which an organic ligand is bonded to the metal element of the metal oxide film to be formed into the processing container, The step of supplying the raw material gas is followed by the step of removing the residual gas remaining in the processing container, The next step is to supply an oxidizing agent for oxidizing the raw material gas into the processing container, The step of supplying the oxidizing agent is followed by the step of removing residual gas remaining in the processing container, It has, A method for forming a film, wherein at least one of the aforementioned steps is a step of supplying a reducing gas containing hydrogen into the processing vessel at the same time as the step of supplying the raw material gas, the supply of which causes the organic ligand to be detached from the organometallic precursor and promotes the thermal decomposition of the organometallic precursor to lower the film formation temperature.

4. Of the aforementioned multiple steps, the one that includes the step of supplying the reducing gas containing hydrogen is: The film formation method according to claim 3, wherein the steps of supplying the raw material gas, removing the residual gas after the supply of the raw material gas, supplying the oxidizing agent, and removing the residual gas after the supply of the oxidizing agent are repeated multiple times, and in each cycle the step of supplying the reducing gas containing the hydrogen is performed.

5. The film formation method according to claim 3 or claim 4, wherein the above-mentioned steps are repeated multiple times.

6. The film formation method according to any one of claims 3 to 5, wherein the step of supplying a reducing gas containing hydrogen is performed simultaneously with the step of supplying the raw material gas, thereby lowering the film formation temperature of the metal oxide film formed in the step and equalizing the optimal film formation temperature of the multi-component metal oxide film.

7. The film formation method according to any one of claims 3 to 6, wherein the plurality of metal oxide films are an InOx film, a GaOx film, and a ZnO film, and the multi-component metal oxide film is an InGaZnO film.

8. The film formation method according to claim 7, wherein the step of forming the GaOx film comprises the step of supplying the hydrogen-containing reducing gas.

9. The film formation method according to claim 7, wherein the steps of forming the GaOx film and forming the InOx film each include the step of supplying a reducing gas containing hydrogen.

10. The film formation method according to claim 9, wherein the amount of hydrogen-containing reducing gas supplied in the step of supplying the hydrogen-containing reducing gas is less when forming the InOx film than when forming the GaOx film.

11. The film formation method according to any one of claims 1 to 10, wherein the step of removing residual gas after the step of supplying the raw material gas also removes residual gas remaining after the step of supplying the reducing gas containing hydrogen.

12. While the steps of supplying the raw material gas, removing residual gas after the supply of the raw material gas, supplying the oxidizing agent, and removing residual gas after the supply of the oxidizing agent are being carried out, a continuous purge gas is supplied to flow continuously into the processing container. The steps of removing residual gas after the step of supplying the raw material gas and removing residual gas after the step of supplying the oxidizer are performed using the continuous purge gas. The film formation method according to claim 11, wherein, in the step of removing residual gas after the step of supplying the raw material gas, an additional purge gas is supplied in addition to the continuous purge gas.

13. The film-forming method according to claim 12, wherein the pressure inside the processing container is reduced during the step of removing residual gas after the step of supplying the raw material gas.

14. The organic ligand of the organometallic precursor is an alkyl group, and the step of supplying the hydrogen-containing reducing gas involves detaching the alkyl group from the organometallic precursor adsorbed on the substrate and terminating it with hydrogen, and in the step of supplying the oxidizing agent, H ２ A film formation method according to any one of claims 1 to 13, which suppresses the generation of oxygen.

15. The method for forming a film according to any one of claims 1 to 14, wherein the reducing gas containing hydrogen is hydrogen gas.

16. A film deposition apparatus for depositing a metal oxide film on a substrate, A processing container in which the substrate is housed, A mounting platform for placing the substrate within the processing container, A gas supply unit that supplies gas to the processing container, An exhaust unit for exhausting the contents of the processing container, Control unit and It has, The control unit, The process involves supplying a raw material gas containing an organometallic precursor in which an organic ligand is bonded to the metal element of the metal oxide film to be formed into the processing container, The step of supplying the raw material gas is followed by the step of removing the residual gas remaining in the processing container, The next step is to supply an oxidizing agent for oxidizing the raw material gas into the processing container, The step of supplying the oxidizing agent is followed by the step of removing residual gas remaining in the processing container, A step of supplying a reducing gas containing hydrogen into the processing container at the same time as supplying the raw material gas, wherein the supply of the reducing gas causes the organic ligand to be detached from the organometallic precursor and promotes the thermal decomposition of the organometallic precursor to lower the film deposition temperature, A film deposition apparatus that controls the gas supply unit and the exhaust unit so that the following occurs.

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