WO2024070685A1

WO2024070685A1 - Film forming method, film forming device, and film forming system

Info

Publication number: WO2024070685A1
Application number: PCT/JP2023/033332
Authority: WO
Inventors: 晋山内
Original assignee: 東京エレクトロン株式会社
Priority date: 2022-09-27
Filing date: 2023-09-13
Publication date: 2024-04-04
Also published as: JP2024047686A

Abstract

This film forming method for forming a molybdenum film or a tungsten film includes: preparing a substrate; forming a film containing molybdenum or tungsten on the substrate by means of ALD using an organometallic source gas containing molybdenum or tungsten and a reactant gas; and performing treatment in which ions are made to act on the film during or after the film formation.

Description

Film forming method, film forming apparatus, and film forming system

This disclosure relates to a film formation method, a film formation apparatus, and a film formation system.

In the semiconductor manufacturing process, tungsten is used as a material to fill contact holes formed in substrates and via holes between wiring. Molybdenum, which has a high melting point like tungsten and is expected to further reduce resistance, is also being considered for use in a similar application.

Patent Document 1 discloses a technique for forming a molybdenum film by ALD or _CVD using _MoCl5 or _MoO2Cl2 as a film-forming source gas.

Patent Document 2 discloses that a tungsten film or a molybdenum film is formed at a low temperature of 400°C or less by using an organic metal gas as the film-forming raw material gas.

JP 2019-44266 A US Patent Application Publication No. 2020/0115798

The present disclosure provides a film formation method, a film formation apparatus, and a film formation system that can form a molybdenum or tungsten film with few impurities in the film at a low temperature with minimal damage to the underlying film.

A film formation method according to one embodiment of the present disclosure is a film formation method for forming a molybdenum film or a tungsten film, and includes the steps of preparing a substrate, forming a film containing molybdenum or tungsten on the substrate by ALD film formation using an organometallic source gas containing molybdenum or tungsten and a reactive gas, and performing a process of reacting ions with the film during or after the film formation.

1 is a flowchart showing a flow of a film forming method according to an embodiment. 1 is a timing chart showing an example of a sequence during ALD film formation using a metal-organic source gas and a reactive gas. FIG. 13 is a diagram showing the results of a composition analysis in the depth direction of a film formed on a substrate by ALD deposition using an organic metal source gas and O ₃ gas while Ar sputter etching the film. 1 is a timing chart showing an example of a sequence in which Ar ion processing is performed during ALD film formation. 13 is a timing chart showing another example of a sequence when Ar ion processing is performed during ALD film formation. 1 is a cross-sectional view that illustrates a film formation apparatus as a first example of an apparatus for carrying out a film formation method according to an embodiment. An example of a sequence in which a process of Ar ion treatment is incorporated into an ALD cycle when forming a film using the film forming apparatus of FIG. 6 will be described. FIG. 2 is a plan view showing a film formation system as a second example of an apparatus for carrying out a film formation method according to an embodiment of the present invention; This figure shows the results of XPS composition analysis of the film surfaces of five samples formed by ALD film formation on a substrate using an organic metal source gas and _O3 gas, and the results of XPS composition analysis of these samples after Ar ion sputtering to a depth of approximately 7 nm from the surface.

The following describes the embodiment with reference to the attached drawings.

＜Overview＞
Patent Document 1 describes ALD film formation using _MoCl5 or _MoO2Cl2 as a film formation raw material _and _H2 gas as a reactive gas. However, when _MoCl5 is used as a film formation raw material, a high-purity metal molybdenum film is obtained, but the substrate (underlying) is etched due to a large amount of Cl contained in the raw material, and the film formation temperature is high at 450°C or more. Also, when _MoO2Cl2 is used as a film formation _raw material gas, etching of the substrate (underlying) is suppressed, but about 20% of oxygen in the raw material remains in the film, and the film formation temperature is high at 500°C or more.

On the other hand, Patent Document 2 describes the formation of a tungsten film or a molybdenum film at a low temperature of 400° C. or less by using an organic metal source gas as a film-forming source gas and O ₂ gas as a reactive gas. However, when forming a film using an organic metal source gas and a reactive gas, there is a concern that components containing carbon and oxygen may remain in the film as impurities. That is, the carbon and oxygen contained in the organic metal source gas, and the components containing oxygen and nitrogen contained in the reactive gas are contained in the film as impurities. Patent Document 2 describes the reduction of the carbon component in the film by using an oxidizing agent, but does not describe a method for reducing the oxygen component or nitrogen component present as an impurity in the film.

As a result of various studies conducted to solve these problems, it was found that it is effective to subject the film to a treatment in which ions are reacted with the film during or after film formation by ALD using an organometallic source gas and a reactive gas containing molybdenum or tungsten.

In this way, by using an organometallic gas as the film-forming raw material gas, the film can be formed at a low temperature with minimal damage to the base caused by chlorine, etc., and the process of reacting with ions provides energy to the film, reducing and reducing the oxide or nitride components that exist as impurities in the film.

<Specific embodiment>
Next, a specific embodiment will be described.

[Film formation method]
FIG. 1 is a flowchart showing a flow of a film forming method according to an embodiment.
As shown in FIG. 1, the film formation method according to this embodiment includes a step (ST1) of preparing a substrate, a step (ST2) of forming a film containing molybdenum or tungsten on the substrate by ALD using an organometallic source gas containing molybdenum or tungsten and a reactive gas, and a step (ST3) of performing a treatment to react ions with the formed film during or after the film formation step.

In the step of preparing a substrate in ST1, the substrate is not particularly limited, but may be a semiconductor substrate (semiconductor wafer). The substrate may be a substrate having an insulating film formed on a base, and the insulating film may have a recess such as a trench or a hole formed therein. In the case of a semiconductor substrate, an insulating film, for example, a _SiO2 film, formed on a silicon substrate may be used. A barrier film such as a TiN film may be formed on the insulating film.

In the film formation step of ST2, the organometallic source gas containing molybdenum or tungsten preferably contains a metal imide bond and/or a metal amide bond, and does not contain a metal-oxygen bond or a metal-halogen bond. By containing a metal imide bond and/or a metal amide bond, the metal-nitrogen bond constituting them has a relatively low bond energy, which is advantageous in that it is highly reactive. In addition, since the bond energy of a metal-oxygen bond or a metal-halogen bond is high, if the metal imide bond or the metal amide bond is contained, there is a disadvantage that the film formation temperature becomes high and oxygen tends to remain. As the organometallic source gas, one containing only a metal imide bond and/or a metal amide bond is more preferable. Examples of such organometallic source gas include ( ^tBuN ) _2Mo ( _NMe2 ) ₂ and ( ^tBuN ) _2Mo ( ^tBuNH ) ₂ .

As the reactive gas, an oxygen-containing gas such as _O3 gas or _O2 gas, or a nitrogen-containing gas such as _NH3 gas can be used.

In the ALD film formation using the metalorganic source gas and the reactive gas in ST2, as shown in FIG. 2, an ALD cycle including (1) supplying the metalorganic source gas to the substrate, (2) purging the remaining metalorganic source gas, (3) supplying the reactive gas to the substrate, and (4) purging the remaining reactive gas is repeated multiple times. In this ALD cycle, the metalorganic source gas is supplied to the substrate and adsorbed to the substrate in a certain amount, and the adsorbed metalorganic source gas reacts with the reactive gas to form a unit film with a controlled thickness. Then, this cycle is repeated multiple times to obtain a film with a desired thickness. As a purge gas for purging the gas, an inert gas such as _N2 gas or a rare gas can be suitably used. The purge gas may be constantly supplied during the ALD film formation.

By using an organic metal source gas as the source gas in this way, low-temperature film formation, for example, film formation at 400° C. or less, is possible. For example, low-temperature film formation at 150° C. has been demonstrated in ALD film formation using the organic metal source gas ( ^tBuN ) ₂ Mo (NMe ₂ ) ₂ gas and O _{3 gas or O 2} _gas . Low-temperature film formation at 350° C. has also been demonstrated in ALD film formation using ( ^tBuN ) ₂ Mo (NMe ₂ ) ₂ gas and NH ₃ gas, and film formation at even lower temperatures is possible by optimizing the conditions.

By using the above-described ALD deposition method, a film containing molybdenum or tungsten is obtained. When an oxygen-containing gas is used as the reactive gas, these films are mainly composed of oxides, and when a nitrogen-containing gas is used as the reactive gas, they are mainly composed of nitrides.

The step of ST3 in which ions are allowed to act on the film is performed during or after the ALD film formation in ST2. During ALD film formation refers to any timing before the film formation is completed. The ions are preferably rare gas ions (rare gas ions) such as He, Ne, and Ar, and more preferably Ar ions. For example, Ar ions are allowed to act on the film by generating a plasma of Ar gas in a chamber that contains the substrate, and applying a bias (e.g., a high-frequency bias) to the stage on which the substrate is placed to attract the Ar ions in the plasma to the substrate. The temperature of this treatment is not particularly limited, and may be performed at room temperature or at the temperature for film formation.

By the treatment of acting with ions, the film during or after the film formation is reduced, and a metal molybdenum film or a metal tungsten film is obtained. That is, the oxides and nitrides in the film are reduced by the energy of the ions, and the oxygen or nitrogen components present as impurities in the film are reduced, resulting in a metal molybdenum film or a metal tungsten film with fewer impurities. For example, when ALD film formation is performed using an organomolybdenum source gas, which is an organometallic source gas, and an oxygen-containing gas, the molybdenum oxides (e.g., MoO ₃ , Mo ₂ O ₃ ) in the film are reduced to a low oxidation number, and finally become metal molybdenum (Mo(VI), Mo(III)→metal Mo(0)). In addition, the reduction action by the treatment of acting with ions can reduce other impurity components such as carbon components.

Such an action of ST3 ions was found when ALD film formation was performed using an organic molybdenum source gas and _O3 gas as a reactive gas, and then the resulting film was analyzed for its depth profile by XPS. When analyzing the depth profile of the film composition by XPS, the composition is analyzed in the depth direction while Ar sputter etching is performed on the film from the surface.

A film was formed on a substrate having a _SiO2 film formed on a Si substrate by ALD deposition using an organic metal source gas and _O3 gas, and the film was subjected to Ar sputter etching while undergoing composition analysis in the depth direction. The results are shown in Figure 3. This figure can also be understood as showing the composition when Ar ions are applied at each point in the ALD cycle.

As shown in Fig. 3, it can be seen that in the film formed by ALD, almost half of the Mo component is metallic Mo. However, since the film is formed in an oxidizing atmosphere using _O3 gas as a reactive gas, in theory, metallic Mo is not generated during film formation. From this, it can be almost concluded that the metallic Mo detected by the composition analysis is generated by reducing oxides ( _MoO3 , _Mo2O3 , etc.) during sputtering with Ar ions. In other words, oxides or _nitrides can be reduced by the action of ions. Since tungsten has the same properties as molybdenum, it is thought that a similar reduction action can be obtained.

In this embodiment, based on this knowledge, a process of treating with ions (ST3) is carried out during or after the formation of a film containing molybdenum or tungsten on a substrate by ALD using an organometallic source gas (ST2), to obtain a metallic molybdenum film or metallic tungsten film.

As described above, the process of reacting with ST3 ions is performed on the film obtained by using an oxygen-containing gas as a reactive gas and the film obtained by using a nitrogen-containing gas as a reactive gas. Of these films, the film produced by using a nitrogen-containing gas is mainly composed of nitride (MoN), while the film produced by using an oxygen-containing gas is mainly composed of oxide (MoO ₃ ), but the nitride has a smaller oxidation number than the oxide. Therefore, during the process of reacting with ST3 ions, the film formed by using a nitrogen-containing gas as a reactive gas can be more easily reduced to metal.

The ion-induced treatment is appropriately set under conditions so that ion energy is obtained so as to exert a desired reduction effect. At this time, the treatment may be performed under conditions so that the film obtained by ALD film formation is sputtered (etched) and removed by ions, but it is also possible to perform the treatment under conditions so that the film is not sputtered and only energy is applied to the film if a desired reduction effect is exerted. Such conditions of only applying energy are more advantageous because they do not involve etching of the film. As for the ion energy, since the amount of Ar sputtering when analyzing the depth profile in XPS is about 0.3 A/s in terms of _SiO2 , it is preferable to set the energy to be equal to or less than the energy at that time.

As described above, the ion-reacting process in ST3 may be performed during or after ALD film formation. When the film to be formed is thin, the film can be sufficiently reduced by performing the ion-reacting process after ALD film formation. However, when the film thickness is large, performing the ion-reacting process after ALD film formation requires a long processing time and may result in insufficient reduction. On the other hand, when performing the ion-reacting process during film formation, the ion energy can be applied to a thinner film than when performing the ion-reacting process after ALD film formation, so the film reduction effect is high and the processing time can be short. For this reason, performing the ion-reacting process during film formation is advantageous when forming a thick film.

When ion treatment is performed during ALD film formation, the timing of Ar ion treatment is arbitrary. For example, ALD film formation and ion treatment may be repeated multiple times, or ion treatment may be incorporated into the ALD cycle.

When ALD film formation and the process of reacting with ions are repeated multiple times, for example, it is performed as shown in FIG. 4. That is, after performing the ALD cycle consisting of (1) supplying metalorganic precursor gas, (2) purging residual gas, (3) supplying reactive gas, and (4) purging residual gas a desired number of times, (5) a process of reacting with ions (ion treatment) and (6) purging residual gas are performed, and this sequence is repeated until the desired film thickness is reached.

When ion treatment is incorporated into the ALD cycle, as shown in Figure 5, the ALD cycle consisting of (1) supply of metalorganic precursor gas, (2) purging of residual gas, (3) supply of reactive gas, (4) purging of residual gas, (5) treatment using ions, and (6) purging of residual gas is repeated until the desired film thickness is achieved.

In this way, when ion treatment is incorporated into the ALD cycle, ions can be applied in each ALD cycle, which makes it possible to achieve a higher film reduction effect and also reduces damage to the surrounding shape.

In addition, in the sequences of Figures 4 and 5, purge gas may be supplied continuously during processing.

When the ion treatment is carried out during ALD film formation, especially when it is incorporated into the ALD cycle, it is preferable to carry out the film formation process in ST2 and the Ar ion treatment process in ST3 in the same equipment. If they are carried out in the same equipment, it is preferable to carry out the ion treatment at the same temperature as the film formation process.

In this embodiment, ALD film formation is performed using an organometallic precursor gas as the film formation raw material gas, so that the damage to the base due to chlorine and the like is small and the film can be formed at a low temperature. In addition, by performing a process in which ions are allowed to act on the film during or after film formation, energy can be imparted to the film to reduce oxides or nitrides present in the film, thereby reducing impurity components. In addition, the reduction effect of the process in which ions are allowed to act can also remove carbon components and the like contained as impurities in the film.

[Device]
Next, an example of an apparatus capable of carrying out the film forming method of the present embodiment will be described.
6 is a cross-sectional view showing a first example of an apparatus for carrying out the film forming method of the present embodiment, which is configured as a film forming apparatus 100 capable of carrying out both the film forming step ST2 and the Ar ion processing step ST3 described above.

This film forming apparatus 100 has a metallic chamber 1 that is roughly cylindrical. An exhaust pipe 11 is connected to the bottom of the chamber 1, and this exhaust pipe 11 is provided with an exhaust mechanism 12 that has an automatic pressure control valve for controlling the pressure inside the chamber 1 and a vacuum pump for evacuating the chamber 1. This exhaust mechanism 12 makes it possible to evacuate the chamber 1 and control the pressure to the desired level.

The side wall of the chamber 1 is provided with a loading/unloading port 13 for loading/unloading the substrate W between the chamber 1 and a substrate transfer chamber (not shown) provided adjacent to the chamber 1, and a gate valve 14 for opening/closing the loading/unloading port 13.

Inside the chamber 1, a mounting table 2 is provided for horizontally supporting the substrate W. The mounting table 2 is supported at the center of the bottom wall of the chamber 1 via a cylindrical insulating member 3, and a hole 1a corresponding to the insulating member 3 is formed in the bottom wall.

The mounting table 2 functions as a lower electrode. The mounting table 2 may be made of metal or ceramics, and if it is made of ceramics, an electrode plate is provided within it. A heater 18 for heating the wafer W is provided inside the mounting table 2. In addition, a high-frequency power supply 16 is connected to the mounting table 2 via a matching unit 15. The high-frequency power supply 16 functions as an ion processing mechanism. The high-frequency power supply 16 is provided below the chamber 1, and a power supply line 17 from the high-frequency power supply 16 is connected to the mounting table 2 via a hole 1a in the chamber 1 and the internal space of the insulating member 3.

The mounting table 2 is provided with multiple wafer support pins (not shown) for supporting and raising and lowering the wafer W, which can be protruded and retracted from the surface of the mounting table 2.

A circular hole is formed in the ceiling wall 1b of the chamber 1, and a disk-shaped shower head 20 that functions as an upper electrode is fitted into the hole. The shower head 20 is grounded via the chamber 1. The shower head 20 has a base member 21 and a shower plate 22. A gas diffusion space 23 is formed between the base member 21 and the shower plate 22. The shower plate 22 has a plurality of gas discharge holes 24 that penetrate from the gas diffusion space 23 to the inside of the chamber 1. A gas introduction hole 25 is formed in the center of the base member 21 so as to penetrate into the gas diffusion space 23. A common pipe 31 of the gas supply mechanism 30 is connected to the gas introduction hole 25, so that gas from the gas supply mechanism 30 is discharged into the chamber 1 via the shower head 20.

With Ar gas supplied into the chamber 1, high-frequency power is applied from the high-frequency power supply 16 to the lower electrode, the mounting table 2, forming a high-frequency electric field between the upper electrode, the shower head 20, and the lower electrode, the mounting table 2, generating Ar plasma. The high-frequency power supply 16 also has the function of applying a high-frequency bias, drawing Ar ions in the Ar plasma to the substrate W on the mounting table 2.

The gas supply mechanism 30 has an MO source gas supply source 41 that supplies an organic metal source gas (MO source gas), an O ₃ gas supply source 42 that supplies O ₃ gas as a reactive gas, a first N ₂ gas supply source 43 and a second N ₂ gas supply source 44 that supply N ₂ gas as a purge gas, and an Ar gas supply source 45 that supplies Ar gas. The MO source gas is an organic molybdenum source gas or an organic tungsten source gas, and may be a liquid or solid source. In that case, it is vaporized in a container and transported by a carrier gas such as N ₂ gas. The reactive gas is not limited to O ₃ gas, but may be other oxygen-containing gas such as O ₂ gas or a nitrogen-containing gas such as NH ₃ gas. The purge gas may be an inert gas other than N ₂ gas.

The first pipe 47 is connected to the MO raw material gas supply source 41, the second pipe 48 is connected to the O ₃ gas supply source 48, the third pipe 49 is connected to the first N ₂ gas supply source 43, the fourth pipe 50 is connected to the second N ₂ gas supply source 44, and the fifth pipe 51 is connected to the Ar gas supply source 45. The third pipe 49 and the fourth pipe 50 are provided on the first pipe 47 side and the second pipe 48 side, respectively. The N ₂ gas flowing from the first N ₂ gas supply source 43 through the third pipe 49 also functions as a carrier gas for the MO raw material gas, and the N ₂ gas flowing from the second N ₂ gas supply source 44 through the third pipe 50 also functions as a carrier gas for the O ₃ gas. The other ends of the first to fifth pipes 47 to 51 are connected to the common pipe 31. The first to fifth pipes 47 to 51 are provided with high-

speed valves

52, 53, 54, 55, and 56, respectively. The flow rates of the gases flowing through the first to fifth pipes 47 to 51 are controlled by flow rate controllers (not shown).

The film forming apparatus 100 has a control unit 60. The control unit 60 is made up of a computer and has a main control unit with a CPU that controls each component of the film forming apparatus 100. The control unit 60 also has an input device, an output device, a display device, and a storage device (storage medium). The components to be controlled are, for example, the heater power supply, the exhaust mechanism 12, the valves and flow rate controllers of the gas supply mechanism 30, the high frequency power supply 16, etc. The main control unit of the control unit 60 causes the film forming apparatus 100 to perform a predetermined operation based on, for example, a processing recipe stored in the storage medium of the storage device.

The film formation apparatus 100 configured as described above performs a film formation method based on a process recipe set in the control unit 60. As described above, the film formation method includes a process of preparing a substrate, a process of forming a film containing molybdenum or tungsten by ALD using an MO raw material gas and a reactive gas, and a process of performing a process of reacting ions during or after film formation. Since the film formation apparatus 100 is equipped with a high-frequency power supply 16 for performing a process of reacting Ar ions, a sequence for performing a process of reacting ions during ALD film formation can be easily realized, and further, the process of reacting ions can be easily incorporated into the ALD cycle.

Below, with reference to Figure 7, we will explain an example sequence when a process for performing ion action processing is incorporated into an ALD cycle.

First, the substrate W is carried into the chamber 1 and placed on the mounting table 2. The mounting table 2 is set to the desired temperature, preferably 400°C or less, by the heater 18. In this state, the processing recipe is started. First, the chamber 1 is evacuated and purged, and then the pressure is increased to the processing pressure to stabilize the temperature of the substrate W. Next, an ALD cycle is performed that incorporates a process of performing a process in which ions are reacted with the ALD film formed using the MO source gas and reactive gas.

The ALD cycle consists of (1) supply of MO source gas, (2) purging of residual gas, (3) supply of _O3 gas, (4) purging of residual gas, (5) treatment with Ar ions (Ar ion treatment), and (6) purging of residual gas. This ALD cycle is repeated until the desired film thickness is reached.

In the supply of the metalorganic source gas in (1), the MO source is vaporized as necessary, and the MO source gas is supplied into the chamber 1 and adsorbed onto the surface of the substrate W. In the purging of the residual gas in (2), the chamber 1 is evacuated while _N2 gas, which is a purge gas, is supplied into the chamber 1, and the residual gas is discharged from the chamber 1. In the supply of the _O3 gas in (3), the reactive gas _O3 gas is supplied into the chamber 1 and reacted with the MO source gas adsorbed onto the surface of the substrate W to obtain a unit film. In the purging of the residual gas in (4), the chamber 1 is purged with _N2 gas, as in (2). In the Ar ion treatment in (5), while Ar gas is supplied into the chamber 1, high frequency power is applied from the high frequency power supply 16 to the lower electrode, which is the mounting table 2, to generate Ar plasma in the chamber 1 and draw Ar ions in the plasma into the substrate W. This applies ion energy to the ALD film, and oxides in the film are reduced. (6) Purging of residual gas is performed by purging the inside of the chamber 1 with _N2 gas, similar to (2) and (4).

The ALD cycle consisting of steps (1) to (6) is repeated until a film having a desired thickness is formed. _N2 gas may be supplied continuously during the process.

After a predetermined number of ALD cycles have been completed, a cycle purge is performed inside chamber 1, and the processing recipe is completed.

Next, a second example of the apparatus will be described. FIG. 8 is a plan view showing a schematic diagram of a second example of the apparatus for carrying out the film formation method of this embodiment, which is configured as a film formation system having an apparatus for performing the above-mentioned ST2 film formation process and an ST3 ion action process.

This film forming system 200 has a vacuum processing section 300, an atmospheric transfer section 400, an airlock section 500, and a control section 600.

The vacuum processing unit 300 has a vacuum transfer chamber 301, a film forming device 302, an Ar ion processing device 303, and a film quality checking device 304. The film forming device 302, the Ar ion processing device 303, and the film quality checking device 304 are connected to the wall of the vacuum transfer chamber 301 via a gate valve G. Note that while the figure shows two film forming devices 302, there may be only one film forming device 302.

The film formation apparatus 302 has a configuration in which the high frequency power supply 16 and the matching box 15 are removed from the film formation apparatus 100, and performs only ALD film formation without performing any ion-induced processing.

The Ar ion processing device 303 does not perform ALD film formation, but instead supplies only Ar gas into the chamber. Like the film formation device 100, it is configured to connect a high-frequency power source to the mounting table to generate Ar plasma in the chamber and draw Ar ions into the substrate, causing the Ar ions to act on the film formed on the substrate.

The film quality confirmation device 304 analyzes the film composition, for example, by XPS, and confirms whether the film composition is as desired. The film quality confirmation device 304 is not essential and does not have to be provided.

A first substrate transfer mechanism 310 is provided in the vacuum transfer chamber 301. The first substrate transfer mechanism 310 transfers substrates W to and from the film forming device 302, the Ar ion processing device 303, the film quality checking device 304, and the airlock section 500. The first substrate transfer mechanism 310 has two

transfer arms

310a and 310b that can move independently.

The atmospheric transfer section 400 has an atmospheric transfer chamber 401. Three carrier attachment ports 402 are provided on the wall of the atmospheric transfer chamber 401 opposite the vacuum processing section 300 to attach carriers C, such as FOUPs, that house substrates W. A second substrate transfer mechanism 410 is provided within the atmospheric transfer chamber 401. The second substrate transfer mechanism 410 transfers substrates W to and from the carriers C and the airlock section 500.

The airlock unit 500 is provided between the vacuum processing unit 300 and the atmospheric transfer unit 400, and enables the transfer of the substrate W between the vacuum transfer chamber 301 and the atmospheric transfer chamber 401 by controlling the pressure between atmospheric pressure and vacuum. The airlock unit 500 has multiple airlock chambers whose pressure can be adjusted between atmospheric pressure and vacuum, and the airlock chambers are connected to the vacuum transfer chamber 301 and the atmospheric transfer chamber 401 via gate valves. In other words, the film formation system 200 of this example is configured to perform film formation processing and Ar ion processing on the substrate in-situ.

The control unit 600 has a main control unit with a CPU (computer), an input device, an output device, a display device, and a storage device. The main control unit controls, for example, substrate processing in the film formation device 302, the Ar ion processing device 303, and the film quality checking device 304, the vacuum exhaust mechanism and gas supply mechanism of these devices and the vacuum transfer chamber 301, pressure control of the airlock unit 500, opening and closing control of the gate valve G, etc. The main control unit also causes the film formation system 200 to perform a predetermined operation based on a processing recipe stored in a storage medium built into the storage device or a storage medium set in the storage device.

In the film formation system 200 configured as described above, the carrier C containing multiple substrates W is connected to the carrier attachment port 402 of the atmospheric transfer chamber 401, and the second substrate transfer mechanism 410 removes the substrates from the carrier C. The substrates are then transferred to the airlock chamber of the airlock section 500, and the airlock chamber is evacuated. The substrates in the evacuated airlock chamber are then transported to the film formation device 302 by the first substrate transfer mechanism 310, and a film mainly made of molybdenum oxide or tungsten oxide is formed by ALD film formation. After the film formation is completed or halfway formed, the substrate W is removed by the substrate transfer device 310 and transported to the Ar ion treatment device 303, where Ar ions are applied to the film formed on the substrate W. Next, the substrate W is transported to the film quality confirmation device 304 as necessary to confirm the film quality. If the substrate W is halfway formed and Ar ion treatment is performed, the treatment in the film formation device 302 and the treatment in the Ar ion treatment device 303 are repeated multiple times. After processing, the substrate W is returned to the carrier C via the airlock 500.

The above-mentioned processing is carried out simultaneously in parallel for multiple substrates W until processing is completed for the number of substrates loaded on the carrier C.

The above describes the case where the film formation process and the process of reacting with Ar ions are performed in situ without breaking the vacuum, but these can also be performed ex situ. In the case of ex situ, the film formation process can be performed in a batch-type device, for example a vertical film formation device. This allows the film formation process to be performed with high throughput. However, in the case of ex situ, the process of reacting with Ar ions is limited to after the ALD film formation.

<Experimental Example>
Next, an experimental example will be described.
Here, ( ^tBuN ) _2Mo ( ^tBuNH ) ₂ was used as the organometallic source gas, and _O3 gas or _O2 gas was used as the reactive gas, and film formation was performed by ALD at low temperatures of 200 to 350°C to create the following five types of samples, A to E.
Sample A Reaction gas: _O3 gas, Film formation temperature: 200°C
Sample B Reaction gas: _O3 gas, film formation temperature: 250°C
Sample C Reaction gas: _O3 gas, Film formation temperature: 350°C
Sample D Reaction gas: _O2 gas, film formation temperature: 350°C
Sample E Reaction gas: _O2 gas, film formation temperature: 250°C

Next, the film surfaces of these samples were subjected to composition analysis by XPS. The results are shown in Fig. 9(a). As shown in Fig. 9(a), all of the conditions had a large amount of impurities due to low-temperature film formation, especially _MoO3 (VI) and no metallic Mo.

Next, for each sample, an Ar ion sputtering process was performed as in the XPS depth profile analysis of the film composition, which corresponds to the process of reacting with ions, and the composition was analyzed by XPS at a depth of about 7 nm from the surface. The results are shown in Figure 9(b). As shown in Figure 9(b), although there is variation depending on the sample, it can be seen that the surface that was sputtered with Ar ions has significantly reduced _MoO3 (VI) to the point that almost none remains, and oxide components with lower oxidation numbers have increased, and metallic Mo is also present in large amounts.

This confirmed that the oxides present in the film can be reduced by the ion treatment, and that a metallic Mo film can be obtained by optimizing the film formation conditions and the Ar ion treatment conditions.

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

For example, in the above embodiment, Ar ions are mainly used as the ion-reactive process, but ions other than Ar may be used as long as they have the desired reducing effect on the ALD-deposited film. Preferably, they are ions of rare gases such as He, Ne, and Ar.

In addition, in the above embodiment, the deposition apparatus shown in FIG. 6 is shown as an example, but FIG. 6 is merely schematic, and various configurations capable of ALD deposition can be used. The same applies to the deposition system shown in FIG. 8.

1; chamber, 2; mounting table, 12; exhaust mechanism, 16; high frequency power source, 18; heater, 20; shower head, 30; gas supply mechanism, 60; control unit, 100; film forming device, 200; film forming system, 300; vacuum processing unit, 301; vacuum transfer chamber, 302; film forming device, 303; Ar ion processing device, 304; film quality confirmation device, 400; atmospheric transfer unit, 500; air lock unit, W; substrate

Claims

A method for forming a molybdenum film or a tungsten film, comprising the steps of:
Preparing a substrate;
forming a film containing molybdenum or tungsten on the substrate by ALD deposition using a metalorganic source gas containing molybdenum or tungsten and a reaction gas;
performing a process of reacting ions with the film during or after the film formation;
The film forming method includes the steps of:
The film formation method according to claim 1, wherein the organometallic precursor gas contains a metal-imide bond and/or a metal-amide bond, and does not contain a metal-oxygen bond or a metal-halogen bond.
The film forming method according to claim 2, wherein the organometallic source gas contains only metal imide bonds and/or metal amide bonds.
The film forming method according to claim 1, wherein the reactive gas is an oxygen-containing gas or a nitrogen-containing gas, oxides or nitrides are present in the film, and the step of performing the treatment to act on the ions provides ion energy to the film to reduce the oxides or nitrides present in the film.
The film forming method according to claim 4, wherein the process of reacting with ions involves reacting with rare gas ions.
The film forming method according to claim 5, wherein the process of reacting with ions involves reacting with Ar ions as the rare gas ions.
The film forming method according to claim 4, wherein the process of reacting with the ions is performed by placing the substrate on a stage in a chamber, generating plasma in the chamber to form ions, and applying a bias to the stage to attract the ions to the substrate.
The film forming method according to claim 7, wherein the treatment of reacting with ions sputters the film.
The film forming method according to any one of claims 1 to 8, wherein the film forming is performed at a temperature of 400°C or less.
The film forming method according to any one of claims 1 to 8, wherein, when the treatment of reacting with ions is performed during the film formation, the ALD film formation and the treatment of reacting with ions are repeatedly performed.
The film forming method according to any one of claims 1 to 8, wherein, when the process of reacting with the ions is performed during the film formation, the process of reacting with the ions is incorporated into the ALD cycle when the ALD film formation is performed.
A film forming apparatus for forming a molybdenum film or a tungsten film, comprising:
A chamber;
a mounting table for mounting a substrate within the chamber;
a gas supply mechanism that supplies a gas containing a metalorganic source gas containing molybdenum or tungsten and a reactive gas into the chamber;
a means for generating a plasma in the chamber and for causing ions in the plasma to act on a substrate;
A control unit;
having
The control unit is
forming a film containing molybdenum or tungsten on a substrate by ALD deposition using the organometallic source gas containing molybdenum or tungsten and the reaction gas;
performing a process of reacting ions with the film during or after the film formation;
and controlling the gas supply mechanism and the means for causing ions in the plasma to act on the substrate so that the above-mentioned is performed.
1. A deposition system for depositing a molybdenum or tungsten film, comprising:
a film formation apparatus for forming a film containing molybdenum or tungsten on a substrate by ALD film formation using an organic metal source gas containing molybdenum or tungsten and a reaction gas;
an ion treatment device that performs a process of reacting ions with the film formed by the film forming device;
having
The ion treatment device is a film formation system that applies ions to the film during or after the film formation by the film formation device.