JP2020180323A - Film deposition apparatus and film deposition method - Google Patents

Abstract

To provide a film deposition apparatus capable of determining surely and simply whether a quality alkali metal film is formed or not; and to provide a film deposition method.SOLUTION: A film deposition apparatus in an embodiment includes a substrate support mechanism, a film deposition source, a detection mechanism and a vacuum vessel. The substrate support mechanism supports a substrate, the film deposition source forms a metal film on the substrate. The detection mechanism detects optically the state of the metal film, during film deposition for forming the metal film on the substrate. The vacuum vessel stores the substrate support mechanism, the film deposition source and the detection mechanism.SELECTED DRAWING: Figure 1

Description

The present invention relates to a film forming apparatus and a film forming method.

Among the film forming devices, for example, there is a device for forming a negative electrode of a battery used for a power storage device. In such a film forming apparatus, an alkali metal such as lithium is used as a film forming material to form an alkali metal film on a substrate (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-212873

However, an alkali metal film such as lithium has high reactivity with oxygen, water and the like. In addition, the capacity of the vacuum container of the above-mentioned film forming apparatus is larger than that of the semiconductor manufacturing apparatus and the like. Therefore, if a small amount of oxygen, water, or the like remains in the vacuum vessel, a part of the alkali metal film may be oxidized and a good quality alkali metal film may not be obtained.

Furthermore, when the alkali metal film comes into contact with air or water vapor after being taken out of the vacuum container, its reaction (poisoning) proceeds. For this reason, it is complicated to determine whether the alkali metal film has already been poisoned during film formation or has been poisoned after being taken out of the vacuum container. In other words, even if a good quality alkali metal film is formed in the vacuum vessel, the alkali metal film may be poisoned after the alkali metal film is taken out from the vacuum vessel.

Therefore, there is a need for a film forming apparatus and a film forming method capable of reliably and easily determining whether or not the alkali metal film is appropriately formed during the film formation of the alkali metal film.

In view of the above circumstances, an object of the present invention is to provide a film forming apparatus and a film forming method capable of reliably and easily determining whether or not a higher quality alkali metal film has been formed.

In order to achieve the above object, the film forming apparatus according to one embodiment of the present invention includes a substrate support mechanism, a film forming source, a detection mechanism, and a vacuum vessel.
The board support mechanism supports the board.
The film-forming source forms a metal film on the substrate.
The detection mechanism optically detects the state of the metal film during the film formation in which the metal film is formed on the substrate.
The vacuum vessel houses the substrate support mechanism, the film forming source, and the detection mechanism.

With such a film forming apparatus, it is possible to reliably and easily determine whether or not a higher quality alkali metal film has been formed.

In the film forming apparatus, the detection mechanism may detect the state of the metal film by the chromaticity of the metal film in a reduced pressure atmosphere.

According to such a film forming apparatus, the detection mechanism detects the state of the metal film by the chromaticity of the metal film in a reduced pressure atmosphere, so that it can be reliably and easily determined whether or not a better quality alkali metal film has been formed. be able to.

The film forming apparatus may further include a control device that controls the film forming conditions of the metal film according to the chromaticity of the metal film detected by the detection mechanism.

According to such a film forming apparatus, a control device for controlling the film forming conditions of the metal film according to the chromaticity of the metal film detected by the detection mechanism is provided, so that a higher quality alkali metal film can be surely obtained. It can be easily formed.

In the film forming apparatus, the control apparatus may control the film forming conditions so that the b ^* value of the metal film in the L ^* a ^* b ^* color space is 10 or less.

According to such a film forming apparatus, the control device controls the film forming conditions so that the b ^* value of the metal film in the L ^* a ^* b ^* color space is 10 or less, so that a higher quality alkali metal film can be obtained. It can be formed reliably and easily.

In the film forming apparatus, the control device may control the film forming conditions so that the L ^* value of the metal film in the L ^* a ^* b ^* color space is 90 or more.

According to such a deposition apparatus, the control device, the L ^* value of the metal film in the L ^* a ^* b ^* color space to control the film forming conditions so that 90 or more, a better quality alkali metal film It can be formed reliably and easily.

In the film forming apparatus, the detection mechanism may detect the state of the metal film by the reflectance of the metal film.

According to such a film forming apparatus, since the detection mechanism detects the state of the metal film by the reflectance of the metal film, it is possible to reliably and easily determine whether or not a better quality alkali metal film is formed. it can.

In order to achieve the above object, the film forming method according to one embodiment of the present invention detects the state of the metal film by an optical method during the film formation in which the metal film is formed on the substrate supported by the substrate support mechanism. At the same time, the metal film is formed on the substrate.

According to such a film forming method, it is possible to reliably and easily determine whether or not a higher quality alkali metal film has been formed.

In the above film forming method, the state of the metal film may be detected by the chromaticity of the metal film in a reduced pressure atmosphere.

According to such a film forming method, since the state of the metal film is detected by the chromaticity of the metal film in a reduced pressure atmosphere, it is possible to reliably and easily determine whether or not a higher quality alkali metal film is formed. ..

In the above film forming method, the metal film may be formed on the substrate under the film forming condition that the b ^* value of the metal film in the L ^* a ^* b ^* color space is 10 or less.

According to such a film forming method, a metal film is formed on the substrate under a film forming condition in which the b ^* value of the metal film in the L ^* a ^* b ^* color space is 10 or less, so that a higher quality alkali metal film can be obtained. It can be formed reliably and easily.

In the above-mentioned film-forming method, the above-mentioned metal film may be formed on the above-mentioned substrate under the film-forming condition where the L ^* value of the above-mentioned metal film in the above-mentioned L ^* a ^* b ^* color space is 90 or more.

According to such a film forming method, a metal film is formed on the substrate under a film forming condition in which the L ^* value of the metal film in the L ^* a ^* b ^* color space is 90 or more, so that a higher quality alkali metal film can be obtained. It can be formed reliably and easily.

In the above film forming method, the state of the metal film may be detected by the reflectance of the metal film.

According to such a film forming method, since the state of the metal film is detected by the reflectance of the metal film, it is possible to reliably and easily determine whether or not a higher quality alkali metal film is formed.

As described above, according to the present invention, there is provided a film forming apparatus and a film forming method capable of reliably and easily determining whether or not a higher quality alkali metal film has been formed.

It is a schematic cross-sectional view which shows an example of the film forming apparatus which concerns on this embodiment. FIG. (A) is a cycle test result of the discharge capacity of the storage battery when the lithium-containing film according to Comparative Example 1 is applied to the negative electrode material of the storage battery. FIG. (B) is a cycle test result of the discharge capacity of the storage battery when the lithium-containing film according to Comparative Example 2 is applied to the negative electrode material of the storage battery. It is a cycle test result of the discharge capacity in the storage battery when the lithium-containing film according to this embodiment is applied to the negative electrode material of the storage battery.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. XYZ axis coordinates may be introduced in each drawing. Further, the same member or a member having the same function may be designated by the same reference numeral, and the description may be omitted as appropriate after the description of the member.

[Film formation device]

FIG. 1 is a schematic cross-sectional view showing an example of a film forming apparatus according to the present embodiment.

As an example of the film forming apparatus according to the present embodiment, the winding type film forming apparatus 1 is shown. This embodiment is applied not only to the take-up type film forming apparatus 1 but also to an in-line type film forming apparatus, a batch type film forming apparatus and the like.

In the film forming apparatus 1, an alkali metal film is formed on the film forming surface 60d of the film 60 while the film 60 runs in the vacuum vessel 70. The film forming apparatus 1 includes, for example, a main roller 10, a film forming source 20, a substrate support mechanism 30, an adhesive plate 40, a detection mechanism 50, and a vacuum vessel 70. Examples of the alkali metal film include a lithium metal film.

The main roller 10 is a tubular roller made of a metal such as iron, stainless steel, or aluminum. The main roller 10 rotates about the central axis C1. The main roller 10 is arranged between the film 60 and the film forming source 20.

A rotation drive mechanism for rotationally driving the main roller 10 is provided outside the film forming apparatus 1. Alternatively, the main roller 10 may have a rotation drive mechanism. Alternatively, the main roller 10 may be a roller that is not rotated by the rotation drive mechanism and freely rotates about the central axis 10c. In the main roller 10, the outer peripheral surface 10s becomes a roller surface, and the outer peripheral surface 10s comes into contact with the non-deposited surface 60r of the film 60 on the side opposite to the film forming surface 60d of the film 60.

When the film 60 is traveling in the direction of arrow A, for example, the main roller 10 in contact with the film 60 rotates counterclockwise. At this time, the speed at which the outer peripheral surface 10s moves about the central axis 10c (tangential speed) is set to, for example, the same speed as the traveling speed of the film 60.

In the present embodiment, a temperature control mechanism such as a temperature control medium circulation system for adjusting the temperature of the outer peripheral surface 10s may be provided inside the main roller 10. The temperature control mechanism is, for example, a temperature control mechanism such as a temperature control medium circulation system.

The film forming source 20 forms a lithium metal film on the film forming surface 60d of the film 60. The film forming source 20 has a melting container 21 (crucible). The film forming source 20 faces the outer peripheral surface 10s of the main roller 10. The thin-film deposition material 25 is housed in the melting container 21. The vapor deposition material 25 is, for example, a metal material such as lithium (Li). The thin-film deposition material 25 is melted in the melting vessel 21 by a method such as resistance heating, induction heating, or electron beam heating.

The substrate support mechanism 30 has both a support mechanism for supporting the film 60 and a traveling mechanism for running the film 60. The substrate support mechanism 30 includes a take-up roller 31, a take-up roller 32, and guide rollers 33a, 33b, 33c, and 33d. A rotary drive mechanism for rotationally driving the unwinding roller 31 and the winding roller 32 is provided outside the film forming apparatus 1. Alternatively, each of the unwinding roller 31 and the winding roller 32 may have a rotation drive mechanism.

The film 60 is previously wound on the unwinding roller 31 and unwound from the unwinding roller 31. After that, the film 60 is subjected to a film forming process by the film forming source 20, and the film 60 is wound by the winding roller 32.

For example, the film 60 continuously unwound from the unwinding roller 31 is supported by the guide rollers 33a and 33b during traveling, and the traveling direction is changed by each of the guide rollers 33a and 33b, and the film 60 is wound around the main roller 10. Will be done.

The film 60 wound around the main roller 10 is supported by the main roller 10 and guided to the guide roller 33c while being in contact with the outer peripheral surface 10s of the main roller 10.

The film 60 separated from the outer peripheral surface 10s of the main roller 10 is supported by the guide rollers 33c and 33d during traveling, and the traveling direction is changed by each of the guide rollers 33c and 33d, and the film 60 is continuously wound around the winding roller 32. Taken.

The adhesive plate 40 is arranged between the film forming source 20 and the main roller 10. The adhesive plate 40 is provided with an opening 41 that opens the film forming source 20 toward the outer peripheral surface 10s of the main roller 10. The protective plate 40 is an example of a vacuum component housed in the vacuum container 70. The vacuum component is not limited to the protective plate 40, and may be, for example, a reflector, a shutter, a support arm, a pipe, or the like.

The detection mechanism 50 optically detects the state of the lithium metal film, for example, the degree of oxidation of the metal film, in-site in a reduced pressure atmosphere during the film formation in which the lithium metal film is formed on the film 60. The detection mechanism 50 includes a chromaticity meter 51, a control device 52, and a light source 53. For example, the detection mechanism 50 detects the degree of oxidation of the lithium metal film by the chromaticity of the lithium metal film.

The chromaticity meter 51 faces the main roller 10 via the film 60. As the chromaticity meter 51, for example, a chromaticity sensor for obtaining the chromaticity is applied by using the CIE L ^* a ^* b ^* color system. The chromaticity meter 51 measures the color of the reflected light of the lithium metal film irradiated by the light source 53.

The chromaticity meter 51 may face the guide roller 33c (or 33d) via the film 60, may face the film 60 between the guide roller 33c and the main roller 10, and may face the film 60 via the film 60. Therefore, it is preferable to face the take-up roller 32. Further, the chromaticity meter 51 may be arranged outside the vacuum container 70. In this case, the vacuum container 70 is provided with a window portion through which the chromaticity meter 51 looks into the vacuum container.

A shutter 56 is provided between the main roller 10 and the chromaticity meter 51. If the chromaticity meter 51 does not measure color, the shutter 56 is closed and the chromaticity meter 51 is shielded by the shutter 56.

The control device 52 determines whether or not the degree of oxidation of the lithium metal film formed on the film 60 is appropriate. The control device 52 determines the state of the lithium metal film deposited on the film 60, for example, the degree of the reaction, based on the color of the lithium metal film. The control device 52 can give a signal when it is determined that the degree of oxidation of the lithium metal film has progressed beyond the target value.

For example, under white light, the Li film has a silver color, LiOH has a white color, and Li ₂ O and Li ₂ CO ₃ have a different color from Li and LiOH such as yellow and orange. The detection mechanism 50 reliably and easily determines that the degree of reaction of the lithium metal film has progressed based on the chromaticity of the lithium metal film.

For example, a plurality of films that have become lithium-containing films due to the progress of oxidation of the lithium metal film are prepared according to the degree of oxidation. Then, the composition of each film is determined by a surface analysis method such as XPS (X-ray photoelectron spectroscopy) and FE-AES (field emission Auger electron spectroscopy). Here, the lithium-containing film means a film in which a lithium metal and a lithium oxide are mixed.

Further, the association between these compositions and the L ^* value, a ^* value, and b ^* value of the lithium-containing film is performed by experiments, simulations, and the like. For example, a calibration curve corresponding to each composition of the lithium-containing film and each of the L ^* value, a ^* value, and b ^* value is stored in the control device 52 as a database.

The detection mechanism 50 detects the chromaticity of the lithium-containing film by the chromaticity meter 51, and transmits the detected signal to the control device 52. The control device 52 gives a signal if the transmitted chromaticity is not at the degree of oxidation used as a power storage device.

As a result, whether or not the lithium metal film formed on the film 60 in the vacuum container 70 can be appropriately used as a power storage device is determined reliably and easily before the lithium metal film is taken out from the vacuum container 70.

Further, the control device 52 may control the film forming conditions of the lithium metal film according to the chromaticity of the lithium metal film detected by the detection mechanism 50.

For example, the control device 52 controls the film forming conditions so that the b ^* value of the lithium metal film in the L ^* a ^* b ^* color space is 10 or less. Alternatively, the control device 52 controls the film forming conditions so that the L ^* value of the lithium metal film is 90 or more.

Here, the film forming conditions are the pressure (vacuum degree) in the vacuum vessel 70, the deposition speed, the traveling speed of the film 60, and the like during film formation.

Further, the detection mechanism 50 may detect the degree of oxidation of the lithium metal film by the reflectance of the lithium metal film. For example, a laser beam having a wavelength of 300 nm or more and 800 nm or less may be used to determine the degree of oxidation of the lithium metal film from the light reflectance of the lithium metal film. Here, it is assumed that a high-quality lithium metal film is formed on the film 60 when the light reflectance is 50% or more.

The light source 53 is, for example, a lighting device (lamp) that emits white light. As a result, the lithium metal film is illuminated with white light. The light source 53 is any one of an incandescent lamp, a xenon lamp, a halogen lamp, an LED, and the like. A shutter 57 is provided in the vacuum vessel 70 so as to face the light source 53, and the light source 53 is shielded by closing the shutter 57. The light source 53 may be installed outside the vacuum container 70, if necessary. In this case, the light source 53 illuminates the vacuum component inside the vacuum vessel 70 from outside the vacuum vessel 70 through a window (not shown).

The film 60 is a substrate to be filmed. The film 60 is a so-called web, which is a long film cut to a predetermined width. The film 60 includes at least one of a copper foil, an aluminum foil, a nickel foil, a stainless foil, and a resin film.

The vacuum vessel 70 houses the main roller 10, the film forming source 20, the substrate support mechanism 30, the adhesive plate 40, a part of the detection mechanism 50, the film 60, and the like. The vacuum vessel 70 can maintain a reduced pressure state, and is passed through an exhaust pipe 71 connected to a vacuum exhaust system (not shown) such as a vacuum pump, for example. As a result, the inside of the vacuum vessel 70 is maintained at a predetermined degree of vacuum.

Gases such as carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and inert gas (Ar, He, etc.) are supplied into the vacuum vessel 70 by the gas supply mechanism 72.

Further, in the present embodiment, in addition to lithium, at least at least indium (In), zinc (Zn), tin (Sn), gallium (Ga), bismuth (Bi), sodium (Na), potassium (K) and the like are used. Either may be housed in the melting container 21.

As described above, in the present embodiment, the film forming apparatus 1 is used to detect the degree of oxidation of the lithium metal film during the film formation in which the lithium metal film is formed on the film 60 supported by the substrate support mechanism 30. However, a lithium metal film is formed on the film 60.

Here, the degree of oxidation of the lithium metal film in a reduced pressure atmosphere is detected by the chromaticity of the lithium metal film. Further, a lithium metal film is formed on the film 60 under a film forming condition in which the b ^* value of the lithium metal film in the L ^* a ^* b ^* color space is 10 or less. Further, a lithium metal film is formed on the film 60 under a film forming condition in which the L ^* value of the lithium metal film in the L ^* a ^* b ^* color space is 90 or more. The degree of oxidation of the lithium metal film may be detected by the reflectance of the lithium metal film.

The sample of this embodiment and the samples of Comparative Examples 1 and 2 were prepared, and their respective colors (visual), chromaticity, and cycle test were examined.

The lithium-containing film of Comparative Example 1 was visually discolored. When the chromaticity of the lithium-containing film of Comparative Example 1 was measured, the L ^* value was −69.93, the a ^* value was 1.41, and the b ^* value was −2.11. When the composition was analyzed, it was found that the lithium-containing film of Comparative Example 1 had a high Li ₂ O composition or Li ₂ CO ₃ composition in addition to pure Li.

The lithium-containing film of Comparative Example 2 was visually yellowish. When the chromaticity of the lithium-containing film of Comparative Example 2 was measured, the L ^* value was 94.06, the a ^* value was −0.08, and the b ^* value was 13.62. When the composition was analyzed, it was found that the lithium-containing film of Comparative Example 2 had a large amount of Li ₂ O composition or Li ₂ CO ₃ composition in the depth direction.

On the other hand, the lithium-containing film of the present embodiment was visually tinged with a metallic luster (silver). When the chromaticity of the lithium metal film of the present embodiment was measured, the L ^* value was 95.85, the a ^* value was −0.46, and the b ^* value was 7.67. It was found that in the lithium metal film of the present embodiment, the Li ₂ O composition and the Li ₂ CO ₃ composition were small in the depth direction, and pure Li was present in a shallower portion.

FIG. 2A is a cycle test result of the discharge capacity of the storage battery when the lithium-containing film according to Comparative Example 1 is applied to the negative electrode material of the storage battery. FIG. 2B is a cycle test result of the discharge capacity of the storage battery when the lithium-containing film according to Comparative Example 2 is applied to the negative electrode material of the storage battery. FIG. 3 shows the cycle test result of the discharge capacity of the storage battery when the lithium-containing film according to the present embodiment is applied to the negative electrode material of the storage battery.

The storage battery is a coin-type battery, LiCoO ₂ is used as the positive electrode material, polypropylene resin is used as the separator, and LiPF _6- based electrolytic solution is used as the electrolytic solution. Further, in each of FIGS. 2A, 2B, and 3A, four storage batteries are evaluated. The initial value (theoretical capacity) of the discharge capacity of the storage battery is about 140 mAh / g.

In Comparative Example 1 shown in FIG. 2A, it was found that the discharge capacity deteriorated significantly in about 5 cycles and the discharge capacity could not be obtained in 10 cycles.

In Comparative Example 2 shown in FIG. 2B, it was found that when 10 cycles were exceeded, the discharge capacity of some storage batteries was significantly reduced from the initial value. In addition, in some other storage batteries, the discharge capacity did not continuously decrease as the cycle increased, and the value varied.

On the other hand, in the present embodiment shown in FIG. 3, it was found that all the storage batteries showed values close to the initial value even after 20 cycles, and the discharge capacity gradually decreased from around 30 cycles. It was. However, it was found that the amount of decrease was overwhelmingly lower than that of Comparative Examples 1 and 2.

As described above, in order to obtain a high-quality lithium metal film applicable to a device such as a power storage device, the b ^* value of the lithium metal film in the L ^* a ^* b ^* color space is preferably 10 or less, and L ^* a. It was found that the L ^* value of the lithium metal film in the ^* b ^* color space is preferably 90 or more.

When the film formation process is performed on the long film 60 for a long time as in the winding type film formation, a poor lithium-containing film may be formed on the film 60 over a long distance. In such a case, the lithium-containing film for this distance cannot be applied to the device, and the lithium-containing film for this distance may be recovered or discarded.

On the other hand, according to the present embodiment, while the lithium metal film is formed on the film 60, whether or not the lithium metal film can be applied to the device can be reliably and easily determined by an optical method. Can be judged. Further, based on the optical information, a high-quality lithium metal film applicable to the device can be reliably formed on the film 60.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made. Each embodiment is not limited to an independent form and can be combined as technically possible as possible.

1 ... Film forming apparatus 10 ... Main roller 10s ... Outer peripheral surface 10c ... Central axis 20 ... Film forming source 21 ... Melting container 25 ... Vapor deposition material 30 ... Substrate support mechanism 31 ... Unwinding roller 32 ... Winding roller 33a, 33b, 33c , 33d ... Guide roller 40 ... Adhesive plate 41 ... Opening 50 ... Detection mechanism 51 ... Chromatic meter 52 ... Control device 53 ... Light source 56, 57 ... Shutter 60 ... Film 60d ... Film formation surface 60r ... Non-deposition surface 70 ... Vacuum container 71 ... Exhaust pipe 72 ... Gas supply mechanism

Claims (11)

A board support mechanism that supports the board and
A film forming source that forms a metal film on the substrate,
A detection mechanism that optically detects the state of the metal film during the film formation in which the metal film is formed on the substrate.
A film forming apparatus including the substrate support mechanism, the film forming source, and a vacuum container accommodating the detection mechanism. The film forming apparatus according to claim 1.
The detection mechanism is a film forming apparatus that detects the state of the metal film by the chromaticity of the metal film in a reduced pressure atmosphere. The film forming apparatus according to claim 2.
A film forming apparatus further comprising a control device for controlling the film forming conditions of the metal film according to the chromaticity of the metal film detected by the detection mechanism. The film forming apparatus according to claim 3.
The control device is a film forming apparatus that controls the film forming conditions so that the b ^* value of the metal film in the L ^* a ^* b ^* color space is 10 or less. The film forming apparatus according to claim 3 or 4.
The control device is a film forming apparatus that controls the film forming conditions so that the L ^* value of the metal film in the L ^* a ^* b ^* color space is 90 or more. The film forming apparatus according to claim 1.
The detection mechanism is a film forming apparatus that detects the state of the metal film by the reflectance of the metal film. A film forming method for forming a metal film on the substrate while detecting the state of the metal film by an optical method during the film formation in which the metal film is formed on the substrate supported by the substrate support mechanism. The film forming method according to claim 7.
A film forming method in which the state of the metal film is detected by the chromaticity of the metal film in a reduced pressure atmosphere. The film forming method according to claim 8.
A film forming method for forming the metal film on the substrate under a film forming condition in which the b ^* value of the metal film in the L ^* a ^* b ^* color space is 10 or less. The film forming method according to claim 8 or 9.
A film forming method for forming the metal film on the substrate under a film forming condition in which the L ^* value of the metal film in the L ^* a ^* b ^* color space is 90 or more. The film forming method according to claim 7.
A film forming method for detecting the state of the metal film by the reflectance of the metal film.

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