Vacuum treatment apparatus and vacuum treatment method

Abstract

To provide a vacuum treatment apparatus and a vacuum treatment method capable of speeding up in a technique of forming a lithium carbonate film on a surface of a lithium metal film.SOLUTION: A vacuum treatment apparatus according to an embodiment of the invention includes a film deposition part, and a plasma treatment part. The film deposition part has an evaporation source having a lithium metal and forms a lithium metal film on a substrate. The plasma treatment part exposes a discharged gas of discharging a gas containing carbon and oxygen to a surface of the lithium metal film formed on the substrate and forms a lithium carbonate film on the surface.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vacuum processing apparatus and a vacuum processing method.

Background Art

[0002] In recent years, with the development of mobile devices such as mobile phones and smartphones, lithium batteries mounted on these devices have attracted attention. In the manufacturing process of lithium batteries, the process of forming lithium metal on a substrate is particularly important, and various techniques have been proposed so far.

[0003] For example, there is a technique of forming lithium metal on a substrate by evaporating lithium metal in a vacuum chamber and depositing the scattered particles on the substrate. Furthermore, there is a technique of suppressing the deterioration of the lithium metal film by forming a protective film formed of lithium carbonate on the surface of the lithium metal film (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above technique, a lithium carbonate film is formed on the surface of the lithium metal film by exposing carbon dioxide gas to the surface of the lithium metal film. In the technique of forming a lithium carbonate film on the surface of the lithium metal film, further speedup is required.

[0006] In view of the above circumstances, an object of the present invention is to provide a vacuum processing apparatus and a vacuum processing method capable of further speedup in the technique of forming a lithium carbonate film on the surface of a lithium metal film.

Means for Solving the Problems

[0007] To achieve the above object, a vacuum processing apparatus according to one embodiment of the present invention includes a film forming unit and a plasma processing unit. The film forming unit has an evaporation source containing lithium metal, and forms a lithium metal film on a substrate. The plasma processing unit exposes the surface of the lithium metal film formed on the substrate to a discharge gas obtained by discharging a gas containing carbon and oxygen, and forms a lithium carbonate film on the surface.

[0008] With such a vacuum processing apparatus, the surface of the lithium metal film formed on the substrate can be more rapidly modified into a lithium carbonate film.

[0009] In the above vacuum processing apparatus, while the substrate is being conveyed from the film forming unit toward the plasma processing unit, the lithium carbonate film is formed on the surface, and the conveyance speed at which the substrate is conveyed may be 1 m / min or more.

[0010] With such a vacuum processing apparatus, the surface of the lithium metal film formed on the substrate can be more rapidly modified into a lithium carbonate film.

[0011] In the above vacuum processing apparatus, the substrate is in the form of a foil, and further includes an unwinding roller for unwinding the substrate, a winding roller for winding up the substrate, and a main roller provided between the unwinding roller and the winding roller in the conveyance direction in which the substrate is conveyed, for winding and conveying the substrate. In the conveyance direction, the plasma processing unit may be disposed between the main roller and the winding roller.

[0012] With such a vacuum processing apparatus, the surface of the lithium metal film formed on the substrate can be more rapidly modified into a lithium carbonate film.

[0013] In the above-described vacuum processing apparatus, the plasma processing unit may include at least one discharge electrode that extends in the width direction of the base material and faces at least one of the first main surface of the base material and the second main surface opposite to the first main surface, a gas supply unit that supplies the gas to the internal space of the plasma processing unit, and a power source that supplies discharge power to the discharge electrode.

[0014] With such a vacuum processing apparatus, the surface of the lithium metal film formed on the base material can be more rapidly modified to a lithium carbonate film.

[0015] In the above-described vacuum processing apparatus, the surface of the discharge electrode may contain C, Mg, Al, Si, Ti, Fe, Ni, Zn, Ag, Sn, and alloys thereof.

[0016] With such a vacuum processing apparatus, the surface of the lithium metal film formed on the base material can be more rapidly modified to a lithium carbonate film.

[0017] To achieve the above object, in a vacuum processing method according to one embodiment of the present invention, using an evaporation source having lithium metal, a lithium metal film is formed on a base material, exposing the surface of the lithium metal film formed on the base material to a discharge gas in which a gas containing carbon and oxygen is discharged, to form a lithium carbonate film on the surface.

[0018] With such a vacuum processing method, the surface of the lithium metal film formed on the base material can be more rapidly modified to a lithium carbonate film.

[0019] In the above-described vacuum processing method, after forming the lithium metal film on the base material, the lithium carbonate film may be formed on the surface while continuously maintaining a reduced pressure state.

[0020] With such a vacuum processing method, the surface of the lithium metal film formed on the base material can be more rapidly modified to a lithium carbonate film.

[0021] In the above-described vacuum treatment method, while transporting the substrate from the film-forming section toward the plasma treatment section, a lithium carbonate film may be formed on the surface, and the transport speed for transporting the substrate may be set to 1 m / min or more.

[0022] With such a vacuum treatment method, the surface of the lithium metal film formed on the substrate can be more rapidly modified to a lithium carbonate film.

[0023] In the above-described vacuum treatment method, the substrate may be in the form of a foil, and the lithium carbonate film may be formed on the surface by a roll-to-roll method.

[0024] With such a vacuum treatment method, the surface of the lithium metal film formed on the substrate can be more rapidly modified to a lithium carbonate film.

[0025] In the above-described vacuum treatment method, a lithium metal film having a thickness of 1 μm or more and 20 μm or less may be formed on the substrate, and a lithium carbonate film having a thickness of 5 nm or more and 30 nm or less may be formed.

[0026] With such a vacuum treatment method, the surface of the lithium metal film formed on the substrate can be more rapidly modified to a lithium carbonate film.

Advantages of the Invention

[0027] As described above, according to the present invention, in the technology of forming a lithium carbonate film on the surface of a lithium metal film, a vacuum treatment apparatus and a vacuum treatment method capable of achieving faster speed are provided.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0029] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, XYZ coordinates may be introduced as necessary. Also, the same members or members having the same function may be given the same reference numerals, and the description may be omitted as appropriate after the description of such members. Also, the numerical values shown below are examples and are not limited to the exemplified numerical values.

[0030] Figs. 1(a) to 1(c) are schematic cross-sectional views showing an outline of a procedure in which the surface of a lithium metal film is modified to a lithium carbonate film in the present embodiment. The lithium metal film is applied, for example, as a part of a component of a lithium ion battery.

[0031] First, as shown in Fig. 1(a), a lithium metal film 111 is formed on the surface of a substrate 10 by a film formation process. Here, as the film formation process, a PVD method is applied. For example, as the film formation process, a vacuum evaporation method using an evaporation source containing lithium metal is applied. As the vacuum evaporation technique, for example, resistance heating, induction heating, or electron beam heating, etc. are applied. The film formation method may be, for example, a batch method (in-line method) or a roll-to-roll method.

[0032] In addition, the "base material" means a foil-shaped base material on which the lithium metal film 111 is formed. The base material may have flexibility or rigidity. For example, as the base material, there are metal foils such as copper foil, nickel foil, iron foil, or stainless steel foil, or resin films such as PET, PEN, PE, PP, PI, and PPS. When a resin film is used as the base material, a film of copper, nickel, iron, or an alloy thereof may be deposited on one or both sides of the resin film in a thickness of 10 nm (nanometers) or more and 1000 nm or less.

[0033] The thickness of the lithium metal film 111 is, for example, 1 μm (micrometers) or more and 20 μm or less. If the thickness of the lithium metal film 111 is less than 1 μm, desired battery characteristics cannot be obtained, and if it is greater than 20 μm, there is a risk of poor productivity, which is not preferable.

[0034] Next, as shown in FIG. 1(b), by carbonating the surface of the lithium metal film 111, a lithium carbonate film 113 with a predetermined thickness is formed. For example, by directly exposing the surface of the lithium metal film 111 formed on the base material 10 to a discharge gas (plasma) 50 in which a gas containing carbon and oxygen is discharged, a lithium carbonate film 113 is formed on the surface of the lithium metal film 111.

[0035] Here, examples of the gas containing carbon and oxygen in the present embodiment include carbon monoxide, carbon dioxide, or a combination of hydrocarbons and oxygen or ozone, and these combinations. Alternatively, as the gas containing carbon and oxygen, a mixed gas of at least one of carbon monoxide, carbon dioxide, and a combination of hydrocarbons and oxygen or ozone, and a noble gas such as argon or helium may be used. The discharge gas 50 contains an ionized gas of carbon monoxide, carbon dioxide, or a combination of hydrocarbons and oxygen or ozone, and a radical active species of carbon monoxide, carbon dioxide, or a hydrocarbon.

[0036] For example, in this embodiment, after the lithium metal film 111 is formed on the base material 10, the lithium carbonate film 113 is continuously formed on the surface of the lithium metal film 111 in-situ while maintaining the reduced pressure state. That is, the surface of the lithium metal film 111 is directly carbonated by the discharge gas 50 without being exposed to the components or moisture in the atmosphere (without being exposed to the components or moisture in the atmosphere).

[0037] For example, the film formation chamber (film formation part) where the lithium metal film 111 is formed and the processing chamber (plasma processing part) where the surface of the lithium metal film 111 is carbonated are adjacent to each other via a gate valve, or the film formation chamber and the processing chamber are continuously adjacent to each other in the same vacuum chamber. These configurations will be described later.

[0038] When a predetermined time elapses after the surface of the lithium metal film 111 is modified to the lithium carbonate film 113, the lithium oxide film 112 is formed between the lithium metal film 111 and the lithium carbonate film 113. This state is shown in FIG. 1(c). As an example of the factor for forming the lithium oxide film 112, for example, a part of the lithium carbonate film 113 in contact with the lithium metal film 111 decomposes, and the lithium oxide film 112 may be formed between the lithium metal film 111 and the lithium carbonate film 113. The factor for forming the lithium oxide film 112 is not limited to this example.

[0039] The thickness of the lithium carbonate film 113 in this state (FIG. 1(c)) is, for example, 5 nm or more and 30 nm or less. When the thickness of the lithium carbonate film 113 is less than 5 nm, the effect of suppressing the deterioration of the lithium metal film decreases, and when it is more than 30 nm, the desired battery characteristics cannot be obtained due to the electrical resistance of the lithium carbonate film. Also, the thickness of the lithium oxide film 112 is, for example, 50 nm or more and 300 nm or less. When the thickness of the lithium oxide film 112 exceeds 100 nm, the desired battery characteristics cannot be obtained.

[0040] The laminated film 11 formed on the base material 10 is used, for example, as a negative electrode for a lithium metal battery. The laminated film 11 (lithium electrode) is composed of a lithium metal film 111 formed on the base material 10, a lithium carbonate film 113, and a lithium oxide film 112 interposed between the lithium metal film 111 and the lithium carbonate film 113. Since the lithium metal film 111 is covered with the lithium carbonate film 113, the surface of the lithium metal film 111 is effectively suppressed from being hydroxylated or nitrided by exposure to the atmosphere.

[0041] The lithium carbonate film 113 of the laminated film 11 is disposed opposite to the positive electrode through an electrolytic solution, thereby constituting a lithium metal battery. The lithium metal battery may be a primary battery or a secondary battery. The positive electrode is composed of, for example, an oxide-based material such as LiNiO2, LiMnO2, or LiCoO2.

[0042] In this embodiment, a gas containing carbon and oxygen is discharged, and this discharged gas 50 is applied to the surface of the lithium metal film 111 formed on the base material 10. Then, by modifying the surface of the lithium metal film 111 with the discharged gas 50, a lithium carbonate film 113 is formed on the surface of the lithium metal film 111.

[0043] The discharged gas 50 is more active than a non-discharged gas (a gas that does not discharge a gas containing carbon and oxygen), and has a higher reactivity with the lithium metal film 111 than the non-discharged gas. That is, the surface of the lithium metal film 111 is directly carbonated by the discharged gas 50 whose discharge conditions are adjusted. As a result, the entire surface of the lithium metal film 111 is carbonated rapidly and uniformly. As a result, a lithium carbonate film 113 having a desired thickness is uniformly formed on the surface of the lithium metal film 111.

[0044] For example, it has been confirmed that when the discharged gas 50 is used, the time required for carbonating the surface of the lithium metal film 111 is reduced to about 1 / 3 compared with the case where a non-discharged gas is used. In this case, it is assumed that the thickness of the lithium carbonate film 113 formed on the surface of the lithium metal film 111 is the same when a non-discharged gas is used and when the discharged gas 50 is used.

[0045] Next, an example of a vacuum processing apparatus for modifying the surface of the lithium metal film 111 into a lithium carbonate film 113 will be described. FIG. 2 is a schematic configuration diagram showing an example of the vacuum processing apparatus of the present embodiment.

[0046] The vacuum processing apparatus 201 includes a film forming unit 211 and a plasma processing unit 213. The film forming unit 211 and the plasma processing unit 213 are sequentially connected via a gate valve 22. The film forming unit 211 and the plasma processing unit 213 can each be evacuated to a predetermined pressure (for example, 1×10 -5 Pa or less) via a vacuum exhaust device 23. A loading load lock chamber (not shown) for loading may be installed on the substrate loading side of the film forming unit 211, and an unloading load lock chamber (not shown) for unloading may be installed on the substrate unloading side of the plasma processing unit 213.

[0047] The film forming unit 211 has an evaporation source (not shown) from which lithium metal evaporates. In the film forming unit 211, a lithium metal film 111 is formed on the loaded sheet-like substrate 10A. The plasma processing unit 213 includes a gas supply unit 24 capable of introducing a gas containing carbon and oxygen, a discharge electrode 25 for discharging a gas containing carbon and oxygen, and a power supply 26 for supplying discharge power to the discharge electrode 25. The discharge gas 50 discharges between the discharge electrode 25 and the vacuum chamber constituting the plasma processing unit 213, or between the discharge electrode 25 and the substrate 10A, and the discharge gas 50 spreads throughout the inside of the plasma processing unit 213.

[0048] In the plasma processing unit 213, the surface of the lithium metal film 111 is carbonated by the discharge gas 50, and a lithium carbonate film 113 is formed on the surface of the lithium metal film 111. For example, when the surface of the lithium metal film is modified into a lithium carbonate film, the plasma processing chamber 151A can be maintained in a reduced pressure atmosphere of 1×10 ―2 Pa or more and 1×10 1 Pa or less.

[0049] Further, the vacuum processing apparatus 201 has a transport mechanism (not shown) that sequentially transports the substrate A to the film formation unit 211 and the plasma processing unit 213 via the gate valve 22. Thereby, the formation of the lithium metal film 111 and the formation of the lithium carbonate film 113 are continuously and sequentially performed.

[0050] FIG. 3 is a schematic configuration diagram showing another example of the vacuum processing apparatus of the present embodiment. The vacuum processing apparatus 202 shown in FIG. 3 is, for example, a roll-to-roll type vacuum processing apparatus.

[0051] The vacuum processing apparatus 202 includes a vacuum chamber 110, a film formation unit 120, a transport unit 130, a plasma processing unit 150, a recovery unit 160, and a transport mechanism 170.

[0052] The vacuum chamber 110 has a sealed structure and is connected to an exhaust line L having a vacuum pump P1. The vacuum chamber 110 has a plurality of partition plates 181, 182, 184, and 185 that partition the film formation unit 120, the transport unit 130, the plasma processing chamber 151A, and the recovery unit 160, respectively. The inside of the vacuum chamber 110 (the film formation unit 120, the transport unit 130, the plasma processing chamber 151A, and the recovery unit 160) is evacuated to a predetermined pressure or less, or maintained in a reduced-pressure atmosphere of a predetermined pressure.

[0053] The film formation unit 120 is a film formation chamber partitioned by the partition plate 181 and the outer wall of the vacuum chamber 110. An evaporation source 121 is disposed inside the film formation unit 120. The evaporation source 121 is an evaporation source from which lithium metal evaporates, and for example, a resistance heating type evaporation source, an induction heating type evaporation source, an electron beam heating type evaporation source, etc. are applicable. Thereby, a lithium metal film is deposited on the first main surface 101 of the substrate 10B.

[0054] The film forming section 120 is connected to the exhaust line L. When the vacuum chamber 110 is evacuated, first, the inside of the film forming section 120 is evacuated. On the other hand, since the film forming section 120 communicates with the transport section 130, when the inside of the film forming section 120 is evacuated, the inside of the transport section 130 is also evacuated. As a result, a pressure difference is generated between the film forming section 120 and the transport section 130. Due to this pressure difference, the vapor flow of the lithium raw material is suppressed from entering the transport section 130.

[0055] The transport section 130 functions as a transport chamber partitioned by partition plates 181, 182, 185 and the outer wall of the vacuum chamber 110. The transport section 130 is disposed above the vacuum chamber 110 in the Y-axis direction. FIG. 3 shows an example in which the first exhaust line L is connected to the film forming section 120. By connecting another exhaust line to the transport section 130, the transport section 130 and the film forming section 120 may be evacuated independently.

[0056] The plasma treatment section 150 includes a plasma treatment chamber 151A, a discharge electrode 51, a power source 155, a gas supply section 154, and an exhaust line 153. The plasma treatment section 150 is disposed between the main roller 172 and the take-up roller 173 in the direction D in which the base material 10B is transported. In the plasma treatment section 150, a gas containing carbon and oxygen discharges between the discharge electrode 51 and the partition plates 182, 184, 185 and the vacuum chamber 110 constituting the plasma treatment section 150, or between the discharge electrode 25 and the base material 10B. As a result, the discharge gas 50 spreads throughout the inside of the plasma treatment chamber 151A. Then, the discharge gas 50 obtained by discharging the gas containing carbon and oxygen is exposed to the surface of the lithium metal film formed on the base material 10B, and a lithium carbonate film is formed on the surface of the lithium metal film.

[0057] The discharge electrode 51 is a rod-shaped or cylindrical electrode. The discharge electrode 51 extends in the width direction of the base material 10B (the direction orthogonal to the direction D in which the base material 10B is conveyed). The outer shape of the cross-sectional shape of the discharge electrode 51 is, for example, circular. The length of the discharge electrode 51 is configured to be equal to or greater than the length of the width of the base material 10B. The discharge electrode 51 may be rotated about its central axis as needed. Also, the discharge electrode of the present embodiment is not limited to one, and at least one may be disposed on at least one of the first main surface 101 of the base material 10B and the second main surface 102 on the side opposite to the first main surface 101. This configuration will be described later.

[0058] The discharge electrode according to the present embodiment is made of, for example, stainless steel. The discharge electrode may contain a metal that forms an alloy with the lithium metal film. For example, a metal layer that forms an alloy with the lithium metal film may be coated on the surface of the discharge electrode. Thereby, the sputtering particles flying from the discharge electrode form a lithium metal film 111 and a lithium alloy. When this lithium metal film is applied as a part of the components of a lithium-ion battery, the influence on the battery characteristics of the lithium-ion battery can be further suppressed. Also, a magnet may be disposed inside the discharge electrode to realize magnetron discharge.

[0059] The power source 155 supplies discharge power for forming the discharge gas 50 to the discharge electrode 51. The discharge power supplied from the power source 155 to the discharge electrode is any one of direct current power, alternating current power, or high-frequency power (RF power).

[0060] The gas supply unit 154 supplies a gas containing carbon and oxygen into the internal space (plasma processing chamber 151A) of the plasma processing unit 150. The plasma processing chamber 151A is connected to the gas supply source S2. The gas supply source S2 stores a gas containing carbon and oxygen. For example, a plurality of gas supply sources S2 are arranged, and carbon monoxide, carbon dioxide, hydrocarbons and oxygen or ozone, and combinations thereof, and noble gases may each be independently supplied into the plasma processing chamber 151A. For example, when a mixed gas composed of carbon dioxide / argon is used, a mixed gas with a carbon dioxide concentration of 5% or more is supplied into the plasma processing chamber 151A.

[0061] The plasma processing chamber 151A is connected to an exhaust line 153 having a pump P3. The plasma processing chamber 151A is configured to be able to maintain a predetermined reduced-pressure atmosphere. For example, the plasma processing chamber 151A can be evacuated to 1×10 -5 Pa or less. Further, when the surface of the lithium metal film is modified to a lithium carbonate film, the plasma processing chamber 151A can be maintained in a reduced-pressure atmosphere of 1×10 ―2 Pa or more and 1×10 1 Pa or less.

[0062] The conveyance mechanism 170 includes an unwinding roller 171, a main roller 172, and a winding roller 173. The main roller 172 is provided between the unwinding roller 171 and the winding roller 173 in the conveyance direction D of the base material 10B. The unwinding roller 171 pays out the base material 10B toward the main roller 172. The main roller 172 winds and conveys the base material 10B between the unwinding roller 171 and the main roller 172. The winding roller 173 winds up the base material 10B wound and conveyed by the main roller 172.

[0063] The unwinding roller 171, the main roller 172, and the winding roller 173 are provided with a rotation drive system (not shown). Each of the unwinding roller 171, the main roller 172, and the winding roller 173 is configured to be rotatable at a predetermined rotational speed around the Z axis. Thereby, in the vacuum chamber 110, the base material 10B is conveyed at a predetermined conveyance speed from the unwinding roller 171 toward the winding roller 173.

[0064] Further, in the main roller 172, a part of the lower portion in the Y-axis direction faces the film forming portion 120 through the opening 181a provided in the partition plate 181. The main roller 172 is arranged at a predetermined interval from the opening 181a and faces the evaporation source 121 in the Y-axis direction.

[0065] The main roller 172 is formed in a cylindrical shape from a metal material such as stainless steel, iron, or aluminum. A temperature control mechanism (not shown) such as a temperature control medium circulation system may be provided inside the main roller 172. The size of the main roller 172 is not limited, and for example, the width dimension in the Z-axis direction is set to be larger than the width dimension of the base material 10B in the Z-axis direction.

[0066] The base material 10B is, for example, a long film cut to a predetermined width. The thickness of the base material 10B is not particularly limited, and is, for example, from several μm to several tens of μm. Also, there are no particular restrictions on the width and length of the base material 10B, and they can be appropriately determined according to the application.

[0067] According to the vacuum processing apparatus 202 configured as described above, while the base material 10B is being conveyed from the film forming portion 120 toward the plasma processing portion 150, the lithium carbonate film 113 is formed on the surface of the lithium metal film 111. For example, the formation of the lithium metal film 111 on the base material 10B in the film forming portion 120 and the formation of the lithium carbonate film 113 in the plasma processing portion 150 (plasma processing chamber 151A) can be continuously performed in the vacuum chamber 110.

[0068] Since the surface of the lithium metal film 111 is directly carbonated by the discharge gas 50 with the discharge conditions adjusted, the entire surface of the lithium metal film 111 is carbonated rapidly and uniformly. This enables an increase in the conveyance speed of the base material 10B. For example, the conveyance speed at which the base material 10B is conveyed in the present embodiment is from 1 m / min to 20 m / min, and at a higher speed, it is from 5 m / min to 20 m / min, and at an even higher speed, it is from 10 m / min to 20 m / min, and at an even higher speed, it is set from 15 m / min to 20 m / min.

[0069] In addition, in order to form the lithium oxide film 112 and the lithium carbonate film 113 with a predetermined thickness, a plurality of guide rollers may be arranged in the plasma processing chamber 151A so as to adjust the path of the substrate 10B passing through the plasma processing chamber 151A to an arbitrary length.

[0070] Figs. 4(a) to 5 are schematic cross-sectional views showing another example of the plasma processing chamber of the present embodiment. The configuration of the plasma processing chamber shown in each of Figs. 4(a) to 5 is another example of the plasma processing chamber 151A of the vacuum processing apparatus 202. The configuration of the plasma processing chamber shown in each of Figs. 4(a) to 5 can also be applied to the plasma processing unit 213 shown in Fig. 2.

[0071] In the example shown in Fig. 4(a), a pair of discharge electrodes 51 and 52 for sandwiching the substrate 10B are arranged in the plasma processing chamber 151A. Each of the pair of discharge electrodes 51 and 52 may be rotated about its respective central axis as necessary. By arranging the pair of discharge electrodes 51 and 52 in the plasma processing chamber 151A, the plasma density of the discharge gas 50 increases, and the discharge gas 50 is more likely to spread in the plasma processing chamber 151A.

[0072] As a result, the surface of the lithium metal film 111 is carbonated more efficiently. Further, since the substrate 10B is sandwiched between the pair of discharge electrodes 51 and 52, when the lithium metal film 111 is formed on both the first main surface 101 and the second main surface 102 of the substrate 10B, the lithium metal films 111 formed on both surfaces can be carbonated simultaneously and efficiently.

[0073] In the example shown in FIG. 4(b), in the discharge electrodes sandwiching the substrate 10B in the plasma processing chamber 151A, the discharge electrodes facing the first main surface 101 are composed of discharge electrodes 51A and 51B, and the discharge electrodes facing the second main surface 102 are composed of discharge electrodes 52A and 52B. The discharge electrodes 51A and 51B are arranged side by side in the transport direction D, and the discharge electrodes 52A and 52B are arranged side by side in the transport direction D. Further, each of the discharge electrodes 51A, 51B, 52A, and 52B may be rotated about its respective central axis as necessary.

[0074] Thus, since the number of discharge electrodes opposed to each main surface of the substrate 10B is increased, the plasma density of the discharge gas 50 further increases, and the discharge gas 50 more easily spreads in the plasma processing chamber 151A.

[0075] As a result, the surface of the lithium metal film 111 is more efficiently carbonated. Further, since the substrate 10B is sandwiched between a set of discharge electrodes 51A and 51B and a set of discharge electrodes 52A and 52B, when the lithium metal film 111 is formed on both the first main surface 101 and the second main surface 102 of the substrate 10B, the lithium metal films 111 formed on both surfaces can be carbonated more efficiently at the same time.

[0076] In the example shown in FIG. 5, a flat plate type discharge electrode 53 is arranged in the plasma processing chamber 151A. By arranging the flat plate type discharge electrode 53 in the plasma processing chamber 151A, the area of the electrode increases, and the plasma density of the discharge gas 50 increases. As a result, the discharge gas 50 more easily spreads in the plasma processing chamber 151A, and the surface of the lithium metal film 111 is efficiently carbonated.

[0077] Further, the thickness of the lithium metal film may be 5 nm or more and 100 nm or less. Even in such a case, the lithium metal film formed on the substrate 10 (substrates 10A and 10B) by the vacuum treatment apparatuses 201 and 202 is carbonated by the discharge gas 50.

[0078] Further, the discharge electrode may contain a metal that forms an alloy with the lithium metal film. For example, a metal layer that forms an alloy with the lithium metal film may be coated on the surface of the discharge electrode. Examples of the metal that forms an alloy with the lithium metal film include C, Mg, Al, Si, Ti, Fe, Ni, Zn, Ag, Sn, and alloys thereof. Thereby, sputtering particles flying from the discharge electrode form a lithium metal film and a lithium alloy. When this lithium metal film is applied as a part of the components of the lithium ion battery, the influence on the battery characteristics of the lithium ion battery can be further suppressed.

[0079] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications can be made, of course. Each embodiment is not necessarily an independent form and can be combined as much as technically possible.

Explanation of reference numerals

[0080] 10, 10A, 10B... Substrate 11... Stacked film 22... Gate valve 23... Vacuum exhaust device 24, 154... Gas supply unit 25, 51, 51A, 51B, 52A, 52B, 53... Discharge electrode 26, 155... Power supply 50... Discharge gas 101... First main surface 102... Second main surface 110... Vacuum chamber 111... Lithium metal film 112... Lithium oxide film 113... Lithium carbonate film 120, 211... Film formation unit 121... Evaporation source 130... Conveying unit 150, 213... Plasma treatment unit 151A... Plasma treatment chamber 153... Exhaust line 160... Recovery unit 170... Conveying mechanism 171... Unwinding roller 172…Main roller 173…Take-up roller 181, 182, 184, 185…Partition plates 181a…Opening 201, 202…Vacuum treatment device P1…Vacuum pump S2…Gas supply source P3…Pump

Claims

1. A film forming section having an evaporation source containing lithium metal for forming a lithium metal film on a substrate, A plasma treatment section for exposing a discharge gas obtained by discharging a gas containing carbon and oxygen to the surface of the lithium metal film formed on the substrate to form a lithium carbonate film on the surface A vacuum processing apparatus comprising.

2. The vacuum processing apparatus according to claim 1, The lithium carbonate film is formed on the surface while the substrate is being conveyed from the film forming section toward the plasma treatment section, The conveyance speed at which the substrate is conveyed is 1 m / min or more Vacuum processing apparatus.

3. The vacuum processing apparatus according to claim 1 or 2, The substrate is in the form of a foil, An unwinding roller for unwinding the substrate, A winding roller for winding up the substrate, A main roller provided between the unwinding roller and the winding roller in the conveyance direction of the substrate for winding and conveying the substrate Further comprising, In the conveyance direction, the plasma treatment section is disposed between the main roller and the winding roller Vacuum processing apparatus.

4. The vacuum processing apparatus according to claim 1 or 2, The plasma treatment section, At least one discharge electrode extending in the width direction of the substrate and facing at least one of the first main surface of the substrate and the second main surface opposite to the first main surface, A gas supply section for supplying the gas to the internal space of the plasma treatment section, [[ID= ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Vacuum treatment method.

9. The vacuum treatment method according to claim 6 or 7, wherein the substrate is in the form of a foil, and the lithium carbonate film is formed on the surface by a roll-to-roll method Vacuum treatment method.

10. The vacuum treatment method according to claim 6 or 7, wherein the lithium metal film with a thickness of 1 μm or more and 20 μm or less is formed on the substrate, and the lithium carbonate film with a thickness of 5 nm or more and 30 nm or less is formed Vacuum treatment method.

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