Film forming apparatus and transport method

Abstract

The invention relates to a film forming apparatus and a conveyance method. The film forming apparatus includes: a transport unit for transporting a substrate; and a film-forming unit for forming, in a vacuum, a Li metal on the film-forming region of the substrate transported by the transport unit. The conveying part is provided with a plurality of rollers. At least one of the plurality of rollers is an anti-wrinkle roller. The static friction coefficient between the anti-wrinkling roller and the Li metal measured in an atmosphere having a dew point of-40 DEG C or less is more than 0.50 and 2.50 or less. The Young's modulus of the surface of the anti-wrinkling roller is 2.5 GPa or less. The surface of the anti-wrinkling roller is made of polypropylene.

Description

Technical Field

[0001] The present invention relates to a film forming apparatus and a transfer method. Background Art

[0002] Lithium batteries have attracted attention as batteries mounted on mobile devices such as smartphones. In the manufacturing process of lithium batteries, it has become a problem that wrinkles are generated during the transfer of the Li metal film formed on the flexible substrate. In particular, there is a problem that wrinkles are generated in the transfer path from the vapor deposition on the flexible substrate to the winding of the flexible substrate.

[0003] In the transfer of a flexible substrate such as a web-shaped substrate, a cylindrical roller is used. In the transfer of the flexible substrate, on the roller, when the compressive stress generated on the flexible substrate exceeds the critical bending stress of the flexible substrate, wrinkles are generated. This phenomenon of wrinkle generation has been modeled. As parameters for constructing this model, for example, the Young's modulus in the transfer direction and width direction of the flexible substrate, the Poisson's ratio of the flexible substrate, the thickness of the flexible substrate, the width of the flexible substrate, the tension, and the coefficient of static friction can be cited. By substituting these parameters into the model, the generation of wrinkles can be predicted theoretically.

[0004] The parameters of such a model are not limited to the parameters of device control. In particular, among the parameters of the above model, the tension related to the physical property value of the flexible substrate as the production object also becomes a parameter that depends on the type of the flexible substrate and the surface treatment process such as physical vapor deposition (PVD). Therefore, it is preferable to adjust the friction coefficient as a parameter of this model.

[0005] As a transfer technique for adjusting the friction coefficient, a guide roller for winding and transferring a thin object such as paper is disclosed in Patent Document 1. For this guide roller, on the outer peripheral surface of the guide roller in contact with the object to be transferred, a low-friction coefficient member having a low friction coefficient with respect to the paper and a high-friction coefficient member having a high friction coefficient with respect to the paper are alternately arranged parallel to the axis of the guide roller.

[0006] As a transfer technique for adjusting the friction coefficient, a roller device 100 for guiding a flexible substrate 10 is disclosed in Patent Document 2. In this roller device 100, the roller device includes a support surface 110 for contacting the flexible substrate 10. The support surface 110 has a coating 120 containing an electronegative polymer.

[0007] Patent Document 1: Japanese Patent Laid-Open No. 7-257798

[0008] Patent Document 2: Japanese Patent Laid-Open No. 2023-78132

[0009] Non-Patent Document 1: Akira Kasahara, Ryusei Kim, Masahiro Tosa, Kazuhiro Yoshihara, "Measurement of Friction Force in High Vacuum Region", J.Vac.Soc.Jpn., vol.43, No.10, P.986-991(2000)

[0010] However, even when using the technologies of Patent Document 1 and Patent Document 2, when transporting a flexible substrate having a Li metal surface in a vacuum, the generation of wrinkles cannot be sufficiently suppressed. Summary of the Invention

[0011] The present invention has been made in view of the above circumstances, and an object thereof is to provide a film forming apparatus and a transfer method that can suppress the generation of wrinkles even when transporting a substrate having a Li metal surface in a vacuum.

[0012] The film forming apparatus according to the first aspect of the present invention includes: a transfer unit for transferring a substrate; and a film forming unit for forming Li metal on a film forming region of the substrate transferred by the transfer unit in a vacuum. The transfer unit includes a plurality of rollers. At least one of the plurality of rollers is an anti-wrinkle roller. The static friction coefficient between the anti-wrinkle roller and the Li metal measured in an atmosphere with a dew point of -40°C or lower exceeds 0.50 and is 2.50 or lower. The Young's modulus of the surface of the anti-wrinkle roller is 2.5 GPa or lower. The surface of the anti-wrinkle roller is made of polypropylene. Thus, the above problem is solved.

[0013] In the film forming apparatus according to the second aspect of the present invention, the film forming apparatus according to the first aspect can be configured such that the dynamic friction coefficient between the anti-wrinkle roller and the Li metal measured in an atmosphere with a dew point of -40°C or lower is 0.10 or higher and 1.20 or lower.

[0014] In the film forming apparatus according to the third aspect of the present invention, the film forming apparatus according to the first or second aspect can be configured such that the surface free energy of the surface of the anti-wrinkle roller is 40 mN / m or lower.

[0015] The transfer method according to the fourth aspect of the present invention uses the anti-wrinkle roller of the film forming apparatus according to the first or second aspect to transfer the substrate.

[0016] The film forming apparatus according to the first aspect of the present invention includes: a transfer unit for transferring a substrate; and a film forming unit for forming Li metal on a film forming region of the substrate transferred by the transfer unit in a vacuum. The transfer unit includes a plurality of rollers. At least one of the plurality of rollers is an anti-wrinkle roller. The static friction coefficient between the anti-wrinkle roller and the Li metal measured in an atmosphere with a dew point of -40°C or lower exceeds 0.50 and is 2.50 or lower. The Young's modulus of the surface of the anti-wrinkle roller is 2.5 GPa or lower. The surface of the anti-wrinkle roller is made of polypropylene.

[0017] Thus, since at least one of the plurality of rollers is an anti-wrinkle roller, the elastic recovery caused by the bending rigidity of the substrate can be promoted. Specifically, the stress applied to the substrate in contact with the surface of the roller can be maintained within the elastic deformation range. In addition, since the Young's modulus of the surface of the anti-wrinkle roller is 2.5 GPa or less, the deformation of the substrate in contact with the surface of the roller can be suppressed within an appropriate range. Therefore, in the film forming apparatus according to the first aspect of the present invention, after forming Li metal in a vacuum, the substrate having a Li metal layer on its surface can be transported while suppressing the generation of wrinkles.

[0018] In the film forming apparatus according to the second aspect of the present invention, the film forming apparatus according to the first aspect is configured such that the dynamic friction coefficient between the anti-wrinkle roller and the Li metal measured in an atmosphere with a dew point of -40°C or lower can be 0.10 or more and 1.20 or less.

[0019] Thus, the elastic recovery caused by the bending rigidity of the substrate can be further promoted.

[0020] In the film forming apparatus according to the third aspect of the present invention, the film forming apparatus according to the first or second aspect is configured such that the surface free energy of the surface of the anti-wrinkle roller is 40 mN / m or less.

[0021] Thus, it is possible to easily make the static friction coefficient between the roller and the Li metal 2.50 or less.

[0022] Thus, the elastic recovery caused by the bending rigidity of the substrate can be further promoted. Moreover, the deformation of the substrate in contact with the surface of the roller can be suppressed within a more appropriate range. In addition, the reaction between the surface of the anti-wrinkle roller and Li can be suppressed, and the life of the roller can be improved.

[0023] In the transfer method according to the fourth aspect of the present invention, the substrate is transferred using the anti-wrinkle roller of the film forming apparatus according to the first or second aspect.

[0024] Thus, even when transferring a substrate having a Li metal layer on its surface in a vacuum, the generation of wrinkles can be suppressed.

[0025] According to the above aspects of the present invention, even when transferring a substrate having a Li metal layer on its surface in a vacuum, the generation of wrinkles can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram showing an example of a film forming apparatus according to an embodiment of the present invention.

[0027] Figure 2 is a cross-sectional view of a substrate having a Li metal layer.

[0028] Figure 3 is a schematic diagram showing Figure 1 an example of the anti - wrinkling roller shown. Detailed implementation mode

[0029] Hereinafter, the roller, the film forming apparatus, and the transfer method according to the embodiment of the present invention will be described. Figure 1 is a schematic diagram showing the film forming apparatus in this embodiment. In Figure 1 , reference numeral 10 is an evaporation apparatus. In Figure 1 , the X - axis, Y - axis, and Z - axis directions represent three mutually orthogonal axis directions. The X - axis and Y - axis represent the horizontal directions. The Z - axis direction represents the direction orthogonal to the horizontal direction. That is, the Z - axis direction represents the vertical direction.

[0030] In the film forming apparatus 10 according to this embodiment, as Figure 2 shown, a Li - metal layer FL containing Li metal is formed on a substrate F (substrate). In the film forming apparatus 10, the Li - metal layer FL can be formed on only one side of the substrate F or on both sides of the substrate F.

[0031] As Figure 1 shown, the film forming apparatus 10 according to this embodiment includes a vacuum chamber 16 (chamber), a transfer unit 11, and a film forming unit 13.

[0032] In this embodiment, the case where the film forming apparatus 10 is a roll - to - roll apparatus will be described. The present invention is not limited to the structure of the roll - to - roll apparatus. For example, it may also be a structure in which a single substrate is transferred by a roll and a film is formed on the transferred single substrate.

[0033] (Vacuum chamber 16)

[0034] The vacuum chamber 16 in the film forming apparatus 10 has a sealable structure. The vacuum chamber 16 is connected to an exhaust line L having a vacuum pump P1. Thus, the vacuum chamber 16 is configured such that its interior can be evacuated or maintained at a specified reduced - pressure atmosphere.

[0035] (Transfer unit 11)

[0036] The transfer unit 11 is configured to transfer the substrate F in the vacuum chamber. In this embodiment, the transfer unit 11 includes: an unwinding roller 111, a winding roller 112, a main roller 113, and a plurality of rollers 115, 116. The roller 116 that contacts the formed Li - metal layer FL is an example of the anti - wrinkling roller described later.

[0037] The unwinding roller 111 and the winding roller 112 each include a rotation drive unit (not shown). The unwinding roller 111 and the winding roller 112 are each configured to be able to rotate around in a direction relative to Figure 1The axis extending in the Z-axis direction orthogonal to the paper surface in [ ] rotates in the direction of arrow R at a prescribed rotational speed.

[0038] The main roller 113 is provided with a rotational drive unit (not shown). The main roller 113 is configured to be able to rotate around an axis extending in the Z-axis direction orthogonal to the paper surface in [ ] at a prescribed rotational speed in the direction opposite to the arrow direction R. Figure 1 The axis extending in the Z-axis direction orthogonal to the paper surface in [ ] rotates in the direction opposite to the arrow direction R at a prescribed rotational speed.

[0039] The unwinding roller 111 is disposed on the upstream side in the conveyance direction of the base material F closer to the base material F than the film forming unit 13. The unwinding roller 111 has a function of feeding the base material F toward the main roller 113. In addition, at an appropriate position between the unwinding roller 111 and the main roller 113, an appropriate number of guide rollers (not shown) that do not have a rotational drive unit may be disposed.

[0040] The main roller 113 is configured to be able to rotate around an axis extending in the Z-axis direction orthogonal to the paper surface in [ ]. The main roller 113 is disposed between the unwinding roller 111 and the winding roller 112 in the conveyance direction of the base material F. Figure 1 At least a part of the lower portion of the main roller 113 in the Y-axis direction in [ ] faces the evaporation source 131 described later. In other words, at least a part of the lower portion of the main roller 113 is disposed at a position facing the evaporation source 131 through the opening 133a provided in the shielding member 133 (shielding portion) described later. Figure 1 The main roller 113 faces the opening 133a with a prescribed interval therebetween. The main roller 113 faces the evaporation source 131 in the Y-axis direction. The main roller 113 is formed in a cylindrical shape from a metal material such as stainless steel, iron, or aluminum. Inside the main roller 113, for example, a temperature control mechanism such as a temperature control medium circulation system (not shown) may be provided. The size of the main roller 113 is not particularly limited, but typically, the width dimension of the main roller 113 in the Z-axis direction is set to be larger than the width dimension of the base material F in the Z-axis direction.

[0041] Each of the plurality of rollers 115, 116 is configured to be able to rotate around an axis extending in the Z-axis direction orthogonal to the paper surface in [ ]. Each of the plurality of rollers 115, 116 may be driven or may not be driven. The roller 116 in contact with the Li metal layer FL is the anti-wrinkle roller described later. Therefore, even when the base material F is conveyed, the generation of wrinkles can be suppressed by the anti-wrinkle roller.

[0042] Each of the plurality of rollers 115, 116 is configured to be able to rotate around an axis extending in the Z-axis direction orthogonal to the paper surface in [ ]. Figure 1 Thereby, in the vacuum chamber, the base material F can be conveyed from the unwinding roller 111 to the winding roller 112 at a prescribed conveyance speed while suppressing wrinkles.

[0043] (Anti-wrinkle roller)

[0044] (Anti-wrinkle roller)

[0045] The roller 116 that functions as an anti-wrinkle roller is a roller that conveys the substrate F having the Li metal layer FL. The static friction coefficient between the roller 116 and the Li metal exceeds 0.50 and is 2.50 or less. The Young's modulus of the surface of the roller 116 is 2.5 GPa or less. Figure 3 An example of the roller 116 is shown. As Figure 3 shown, the roller 116 has a cylindrical rotating member 21 and a support surface layer 22. The support surface layer 22 covers at least the area of the outer peripheral surface of the rotating member 21 that comes into contact with the Li metal. The surface of the anti-wrinkle roller is made of polypropylene. Figure 3 The arrow shown in is the rotation direction of the roller 116.

[0046] (Rotating member 21)

[0047] The rotating member 21 is formed into a cylindrical shape from a metal material such as stainless steel, iron, or aluminum.

[0048] (Support surface layer 22)

[0049] The support surface layer 22 covers at least the area of the outer peripheral surface of the rotating member 21 that comes into contact with the Li metal. The support surface layer 22 may also cover the entire outer peripheral surface of the rotating member 21. The thickness of the support surface layer 22 is not particularly limited as long as it can convey the substrate F. The thickness of the support surface layer 22 is, for example, 1 mm to 100 mm.

[0050] (Static friction coefficient)

[0051] The static friction coefficient between the roller 116 and the Li metal (hereinafter sometimes referred to as the static friction coefficient with respect to Li) exceeds 0.50 and is 2.50 or less. Here, the static friction coefficient between the support surface layer 22 and the Li metal is the static friction coefficient with respect to Li. By setting the static friction coefficient between the roller 116 and the Li metal to exceed 0.50 and be 2.50 or less, the elastic recovery caused by the bending rigidity of the substrate can be promoted.

[0052] (Dynamic friction coefficient)

[0053] The dynamic friction coefficient between the roller 116 and the Li metal (hereinafter sometimes referred to as the dynamic friction coefficient with respect to Li) is preferably 0.10 or more and 1.20 or less. Here, the dynamic friction coefficient between the support surface layer 22, the roller, and the Li metal is the dynamic friction coefficient with respect to Li. By setting the dynamic friction coefficient between the roller 116, the roller, and the Li metal to be 0.10 or more and 1.20 or less, the elastic recovery caused by the bending rigidity of the substrate can be further promoted.

[0054] The ratio of the static friction coefficient to Li to the dynamic friction coefficient to Li (static friction coefficient to Li / dynamic friction coefficient to Li) is preferably 1.00 to 2.50. By setting the static friction coefficient to Li / dynamic friction coefficient to Li to 1.00 to 2.50, the elastic recovery caused by the bending rigidity of the substrate can be further promoted, and the generation of wrinkles can be further suppressed.

[0055] The static friction coefficient and the dynamic friction coefficient of the roller 116 can be measured, for example, by the following method. In this measurement, an automatic friction and wear analysis device (for example, TSf-303 manufactured by Kyowa Interface Science Co., Ltd., hereinafter sometimes referred to as the analysis device) is used. A sample having the same material as the outer peripheral surface of the roller 116 is arranged under the analysis device. A copper foil coated with Li metal is pasted onto the contact member using double-sided tape. The shape and specifications of the contact member are, for example, a surface contact member (TSf No. 9210, contact surface size 10 mm × 10 mm) manufactured by Kyowa Interface Science Co., Ltd. In the measurement in an atmosphere with a dew point of -40°C or lower, the measurement is performed three times under the conditions of a distance of 50 mm, a speed of 100 mm / s, and a load of 100 g. The average values of the obtained static friction coefficient and dynamic friction coefficient are respectively set as the static friction coefficient to Li and the dynamic friction coefficient to Li.

[0056] (Young's modulus)

[0057] The Young's modulus of the surface (outer peripheral surface) of the roller 116 is 2.5 GPa or less. Here, the Young's modulus of the surface is the Young's modulus of the support surface layer 22. By setting the Young's modulus of the surface to 2.5 GPa or less, the deformation of the substrate in contact with the surface of the roller can be suppressed within an appropriate range. The Young's modulus can be 0.5 GPa or more.

[0058] The Young's modulus of the surface can be measured by the following method. Prepare a sample having the same material as the surface of the roller 116. For the sample, the measurement can be performed based on JIS K 7161.

[0059] (Surface free energy)

[0060] The surface free energy of the outer peripheral surface of the roller 116 is preferably 40 mN / m or less. Since the surface free energy is 40 mN / m or less, it is easy to make the static friction coefficient to Li 2.50 or less. Furthermore, by setting the surface free energy in this way, the change in each friction coefficient (static friction coefficient and dynamic friction coefficient respectively) can be prevented, and a stable friction coefficient can be maintained for a long time. A more preferable surface free energy is 30 mN / m or less. Thereby, it is possible to expect to prevent at least one of adhesion, corrosion, and wear. Therefore, a further long-term stability can be maintained. Here, the surface free energy of the roller 116 is the surface free energy of the support surface layer 22.

[0061] The surface free energy of the roller 116 can be measured by the following method. The surface free energy can be measured using a general contact angle meter. Specifically, liquids with known surface free energy values (water, methylene iodide) are used. The contact angle of the sample is measured, and the theoretical formula in D.K. Owens and R.C. Wendt, J. Appl. Polym. Sci., 13, 1741 (1969) is used. Thus, the surface free energy of the sample can be calculated. For example, 2 μl of pure water and methylene diiodide are respectively dropped onto test pieces collected from the surface of the roller 116, and the contact angle (θ) is measured by a contact angle meter. The surface free energy value γ can be calculated by using the obtained contact angle through the following Owens formula s .

[0062] 1 + cosθ = 2[(γ s d γ l d ) 1 / 2 / γ l +(γ s p γ l p ) 1 / 2 / γ l

[0063] Here, in the above formula, γ s represents the surface free energy of the solid, γ l represents the surface free energy of the liquid, the subscript d represents the dispersion force component, and the subscript p represents the polar force component

[0064] (Arithmetic mean surface roughness Sa)

[0065] The arithmetic mean surface roughness Sa of the outer peripheral surface of the roller 116 is preferably 1.00 μm or less. By setting the arithmetic mean surface roughness Sa of the outer peripheral surface of the roller 116 to 1.00 μm or less, the generation of wrinkles can be further suppressed

[0066] The arithmetic mean surface roughness Sa can be obtained according to ISO 25178. It can also be measured by collecting a test piece from the surface of the roller 116

[0067] ​The surface of the roller 116 is preferably composed of one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene. In the case of having the support surface layer 22, the support surface layer 22 preferably contains one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene. By forming the surface of the roller 116 from one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene, the elastic recovery caused by the bending rigidity of the substrate F can be further promoted. Furthermore, the deformation of the substrate in contact with the surface of the roller can be suppressed within a more appropriate range. The surface of the roller 116 is more preferably composed of polypropylene. In the case of having the support surface layer 22, the support surface layer 22 is preferably composed of polypropylene. By forming the surface of the roller 116 from polypropylene, the reaction between the surface of the roller 116 and the Li metal can be suppressed. Thereby, it is possible to expect to prevent at least one of adhesion, corrosion, and wear. Therefore, further long-term stability can be maintained.

[0068] In the film forming apparatus 10, at least one of the plurality of rollers 115 and 116 is an anti-wrinkle roller. The coefficient of static friction of the anti-wrinkle roller with respect to the Li metal is 2.50 or less. The Young's modulus of the surface of the anti-wrinkle roller is 2.5 GPa or less.

[0069] Among the plurality of rollers 115 and 116, when the roller in contact with the Li metal layer FL is a contact roller, the ratio of the number of anti-wrinkle rollers to the total number of contact rollers is preferably 30% or more. In this case, since the contact ratio between the Li metal layer FL and the anti-wrinkle roller increases, the substrate F can be transported while suppressing the generation of wrinkles. Here, since all the contact rollers can be anti-wrinkle rollers, the ratio of the number of anti-wrinkle rollers to the total number of contact rollers can also be 100%. By doing so, the generation of wrinkles can be further suppressed.

[0070] (Film forming section 13)

[0071] The film forming section 13 forms the Li metal layer FL in the film forming region of the substrate F in a vacuum. Since the Li metal is formed in a vacuum, only an inevitable reaction layer due to oxidation or the like exists on the surface of the Li metal layer FL. The film forming section 13 has an evaporation source 131 and a shield 133 inside. In addition, the film forming section 13 is connected to an exhaust line (not shown). The main roller 113 constitutes the film forming section 13.

[0072] The evaporation source 131 (film forming source supply section) of the film forming section 13 is a Li evaporation source that evaporates Li metal. The evaporation source 131 is composed of, for example, a resistance heating type evaporation source, an induction heating type evaporation source, an electron beam heating type evaporation source, or the like.

[0073] The film forming section 13 is maintained in a specified reduced pressure atmosphere through the exhaust line L.

[0074] In the film forming section 13, asFigure 1 As shown, a shielding member 133 is provided between the evaporation source 131 (film forming source) and the main roller 113. The shielding member 133 has an opening 133a. The opening 133a is a film forming range defining portion that defines the film forming range.

[0075] The shielding member 133 is arranged to be substantially parallel to the substrate F wound around the main roller 113.

[0076] The substrate F is, for example, a long strip of film cut to a specified width. Figure 1 In the example shown, the width of the substrate F is the length of the substrate F in the Z-axis direction. The substrate F is made of a metal structure such as copper, nickel, stainless steel, or iron. The material of the substrate F is not limited to such materials. As the material of the substrate F, resin films such as PE (polyethylene) film, CPP (cast polypropylene) film, OPP (oriented polypropylene) film, PET (polyethylene terephthalate) film, PEN (polyethylene naphthalate) film, PPS (polyphenylene sulfide) film, and PI (polyimide) film can be used. The thickness of the substrate F is not particularly limited and is, for example, 1 μm to 20 μm. In addition, there are no particular restrictions on the width and length of the substrate F, and they can be appropriately determined according to the use.

[0077] The Li metal layer FL present on the substrate F is usually formed by evaporation coating. The inventors believe that when the thickness of the Li metal layer FL is 0.1 μm or more, the influence of the Li metal layer dominates the respective friction coefficients. Regarding the reason, the inventors believe that since Li metal has a relatively high surface tension, the Li metal layer forms an island-like or mesh structure when the thickness is less than 0.1 μm. As a result, a part of the surface of the substrate F as the base is exposed, and therefore the inventors believe that the respective friction coefficients exhibited by the rollers for handling are undeniably affected by the substrate F as the base and cannot be the relevant friction coefficients. The inventors conducted multiple experiments and confirmed that under the above conditions, the upper and lower limits of the specimens of the dynamic friction coefficient are in the range of 0.2 to 1.20.

[0078] For the evaporation coating of a general net-shaped continuous substrate F (continuous substrate, substrate), due to technical limitations in the device and handling or limitations in the battery structure, it is difficult to form a film over the entire 100% range in the width direction of the continuous substrate F. Therefore, there are inevitably non-film-forming surfaces at both ends in the width direction of the continuous substrate F. That is, there are steps composed of film-forming surfaces and non-film-forming surfaces at both ends in the width direction of the continuous substrate F after the Li metal layer FL is evaporated onto the continuous substrate F.

[0079] This step is manifested, for example, by the shield 133 that functions as a mask disposed during vapor deposition. Here, the shield 133 that functions as a mask has a width dimension narrower than the width direction of the continuous substrate F. The shield 133 is configured to prevent the Li vapor evaporated from the vapor deposition source 131 from reaching both end portions of the continuous substrate F in the width direction.

[0080] Alternatively, this step is manifested by a method of placing strip-shaped substrates at both end portions of the continuous substrate F and transporting them synchronously with the continuous substrate F, so as to obtain a mask effect in a state where the strip-shaped substrates are in contact with the continuous substrate F.

[0081] Here, from the perspective of transporting the substrate without generating wrinkles on the substrate, it is known that the starting point of wrinkle generation is where the vertical resistance changes discontinuously at the contact portion between the substrate and the transport roller when the change in the vertical resistance exceeds a certain range. Through multiple experiments by the inventors, it has been clarified that by making the step 20 μm or less, the generation of wrinkles caused by transportation can be suppressed.

[0082] When moving the continuous substrate using a transport roller, in order to prevent the generation of wrinkles, if the vertical resistance is set to zero, wrinkles can be prevented. However, when vapor depositing on the continuous substrate F with a thickness of about 1 to 20 μm, a vertical resistance needs to be applied through tension or the like. The reason is that by applying the vertical resistance, the heat dissipation based on contact heat conduction can effectively function, so that vapor deposition film formation can be carried out without causing deformation, modification, reaction, etc. of the substrate due to heat. In addition, the vertical resistance acting in the measurement of each coefficient of friction may physically disrupt the surface layer of the Li metal layer containing adsorbed gas. Therefore, the vertical resistance is preferably in the range of the tension used when vapor depositing Li metal on the continuous substrate F. Generally, the tension on the substrate width used when vapor depositing Li metal on the continuous substrate is 2.6 N / m to 260 N / m. Therefore, it is preferable to measure with the vertical resistance in this range. In addition, the measurement of each static coefficient of friction described above simulates the vertical resistance when the tension is equivalent to 50 N / m.

[0083] The tension on the substrate width (applied tension / width of the substrate) is preferably 260 N / m or less, and the product of the tension on the substrate width and the static coefficient of friction is preferably 650 N / m or less. By setting the product of the tension on the substrate width and the static coefficient of friction to 650 N / m or less, the generation of wrinkles can be further suppressed.

[0084] The film forming apparatus 10 has the above structure.

[0085] In addition, although not shown in the figures, the film forming apparatus 10 also has a control unit for controlling the evaporation source 131, the transfer unit 11, the vacuum pump P1, etc. The above control unit is composed of a computer including a CPU and a memory, and controls the overall operation of the film forming apparatus 10.

[0086] In addition, the film forming apparatus 10 is not limited to the structure shown in the figure. For example, the structure of the film forming apparatus 10 can be appropriately changed in terms of the configuration and size of the film forming unit 13, the transfer unit 11, the vacuum pump, etc., and the evaporation source, etc. Alternatively, any one of the above structures in the film forming apparatus 10 may not be provided. In addition, the film forming apparatus 10 may also have a structure for forming the Li metal layer FL by sputtering method.

[0087] The arithmetic mean surface roughness Sa can be 0.02 μm or more.

[0088] The static friction coefficient against Li / the dynamic friction coefficient against Li can be 1.15 or more. The static friction coefficient against Li / the dynamic friction coefficient against Li can be 2.00 or less.

[0089] The dynamic friction coefficient against Li can exceed 0.50. By making the dynamic friction coefficient against Li exceed 0.50, the transfer efficiency of the substrate F can be improved.

[0090] The film forming apparatus 10 may further have a first treatment unit (not shown) for oxidizing the surface of the Li metal layer FL. In the first treatment unit, by oxidizing the surface of the Li metal layer FL, the specified electrical characteristics required for the negative electrode material of the lithium battery can be stably ensured, and the lithium carbonate film described later can be easily and stably formed.

[0091] In this case, the first treatment unit has a first treatment chamber, a first gas supply line, and a first pressure adjustment mechanism. In the first treatment chamber, the oxidation treatment of the Li metal layer FL is performed using the first treatment gas. The first gas supply line supplies the first treatment gas to the first treatment chamber. The first pressure adjustment mechanism adjusts the pressure of the first treatment chamber. The first treatment gas is not particularly limited as long as it is a gas containing oxygen. The first treatment gas is typically oxygen or a mixed gas of oxygen and argon. By the first pressure adjustment mechanism, the atmosphere in the first treatment chamber is maintained in a specified reduced pressure atmosphere, the gas pressure of the first treatment gas in the first treatment chamber is adjusted to a specified pressure, and the discharge of the first treatment gas to the outside of the first treatment chamber is suppressed.

[0092] The film forming apparatus 10 may further have a second treatment unit (not shown) for carbonating the surface of the oxidized Li metal layer FL. In the second treatment unit, by carbonating the surface of the oxidized Li metal layer FL, the surface of the Li metal layer FL can be easily and effectively protected from being hydroxylated and nitrided.

[0093] In this case, the second processing unit includes a second processing chamber, a second gas supply line, and a second pressure adjustment mechanism. In the second processing chamber, the carbonation treatment of the Li metal layer FL is performed using a second processing gas. The second gas supply line supplies the second processing gas to the second processing chamber. The second pressure adjustment mechanism adjusts the pressure of the second processing chamber. The second processing gas is not particularly limited as long as it is a gas containing carbon and oxygen. Specifically, as the second processing gas, for example, a mixed gas of a noble gas such as argon and carbon dioxide is used. In this case, the amount of carbon dioxide contained in the second processing gas can also be appropriately set. For example, the amount of carbon dioxide in the second processing gas is about 5% by volume ratio. Through the second pressure adjustment mechanism, the atmosphere in the second processing chamber is maintained in a specified reduced-pressure atmosphere, the gas pressure of the second processing gas in the second processing chamber is adjusted to a specified pressure, and the discharge of the second processing gas to the outside of the second processing chamber is suppressed. The second processing chamber may also be constituted by the same processing chamber as the first processing chamber. In this case, it is configured to be able to switch the types of gases introduced into the first processing chamber.

[0094] It is also possible not to provide the first processing chamber and the second processing chamber, and perform the oxidation treatment or the carbonation treatment by introducing the first processing gas and the second processing gas into the vacuum chamber 16, respectively.

[0095] When the Li metal layers FL are provided on both surfaces of the base material F, the main roller 113 can also be used as an anti-wrinkle roller. Specifically, the main roller 113 may also include the support surface layer 22.

[0096] In the present embodiment, the roller 116 is composed of a cylindrical rotating member 21 and a support surface layer 22 that covers at least the region in contact with the Li metal on the outer peripheral surface of the rotating member 21. As a modified example, the roller 116 may also be composed of a cylindrical rotating member made of the same material as the support surface layer 22.

[0097] [Examples]

[0098] Hereinafter, examples of the present invention will be described.

[0099] [Anti-wrinkle roller]

[0100] An anti-wrinkle roller with a surface layer material of polypropylene (labeled as PP in Table 1) and an anti-wrinkle roller of hard chromium-plated aluminum (labeled as HCr in Table 1) were prepared. Evaluation test pieces were used for the evaluation of the coefficient of friction, surface free energy, Young's modulus, and surface roughness.

[0101] [Measurement of coefficient of friction]

[0102] An automatic friction and wear analysis device (TSf-303 manufactured by Kyowa Interface Science Co., Ltd., hereinafter sometimes referred to as the analysis device) was used. A sample having the same material as the outer peripheral surface of the roller 116 was placed under the analysis device. A copper foil coated with Li metal was adhered to the contact member (a surface contact member (TSf No. 9210, contact surface size: 10 mm × 10 mm) manufactured by Kyowa Interface Science Co., Ltd.). In the measurement in an atmosphere with a dew point of -40°C or lower, the measurement was performed three times under the conditions of a distance of 50 mm, a speed of 100 mm / s, and a load of 100 g. The average values of the obtained static friction coefficient and dynamic friction coefficient were set as the static friction coefficient against Li and the dynamic friction coefficient against Li, respectively.

[0103] Due to the limitations of the analysis device, the measurement of each friction coefficient was carried out in a controlled atmospheric atmosphere. However, the atmosphere of the anti-wrinkle transport environment targeted by the present invention is an atmosphere in which Li evaporation can be performed, and the influence of the gas molecular layer adsorbed on the surface of the Li metal layer immediately after evaporation onto the substrate is excluded from the numerical values. Therefore, the inventor estimated that the value is about 2 to 4 times. The reason is that the general pressure range for performing Li evaporation is 10 -4 Pa or less, and in this pressure range, as shown in FIG. 4 of Non-Patent Document 1, it can be expected that the friction coefficient will increase non-linearly. That is, from the perspective of preventing wrinkles, the measured value in the atmospheric atmosphere also includes a measurement error, and the measured value should be regarded as a value multiplied by the above magnification, so careful handling is required.

[0104] (Surface free energy)

[0105] 2 μl of pure water and diiodomethane were respectively dropped onto test pieces (evaluation test pieces) having the same surface material as the above-mentioned roller. Then, the contact angle (θ) was measured with a contact angle meter. Using the obtained contact angle, the surface free energy value γ was calculated by the above-mentioned Owens formula. s When the surface free energy is 40 mN or less, it is designated as A; when the surface free energy is more than 40 mN and less than 60 mN, it is designated as B; when the surface free energy is 60 mN or more, it is designated as C. The obtained results are shown in Table 1.

[0106] (Young's modulus)

[0107] The Young's modulus of the test pieces (evaluation test pieces) having the same surface material as the above-mentioned roller was measured. The Young's modulus of PP was measured based on JIS K7161, and the Young's modulus of HCr-Al was measured based on JIS Z2241. The obtained results are shown in Table 1.

[0108] (Surface roughness)

[0109] Using a sample (test piece for evaluation) having the same surface material and surface roughness as the above roller, the surface roughness was determined according to ISO 25178. The obtained results are shown in Table 1.

[0110] Using the anti-wrinkle roller described in Table 1 Figure 1 The film forming apparatus shown. The Li metal layer was formed and transported under the following transport speed and film forming conditions. The result of no wrinkles during transport was evaluated as A. The result of 1 to 2 wrinkles during transport was evaluated as B. The result of 3 or more wrinkles during transport was evaluated as C. The results are shown in Table 2.

[0111] Conveying speed of substrate F: 0.01~20.0m / min

[0112] Substrate F: Cu foil (10 μm)

[0113] Li metal film thickness in film forming section 13: 5 μm

[0114] As shown in Table 2, Examples 1 and 2 that satisfy the conditions of the static friction coefficient and the Young's modulus have a small number of wrinkles.

[0115] The surface free energy of the support surface layer 22 in this embodiment is 40 mN / m or less. However, in the case where the degradation of the resin caused by the high activation energy of the Li metal layer just after evaporation becomes a problem, the surface free energy is more preferably 30 mN / m or less. By doing so, the change of each friction coefficient accompanying the degradation of the resin can be prevented, and a stable friction coefficient can be maintained for a long time.

[0116] In addition, it is conceivable that the change of each friction coefficient over time caused by the redox reaction of Li and the resin is related to the generation of wrinkles, wherein the redox reaction of Li and the resin is considered to be caused by contact with Li. In this case, it is preferred to adopt a fluorine-free structure in the surface layer of the support surface layer 22. Thus, as described above, a stable friction coefficient can be maintained for a long time.

[0117] (tension)

[0118] When the rollers for which evaluations A and B were obtained were used, the tension relative to the width of the substrate used when Li metal was vapor-deposited on the continuous substrate was examined.

[0119] The results show that the generation of wrinkles can be further suppressed by setting the tension relative to the substrate width (applied tension / substrate width) to 260 N / m or less and the product of the tension relative to the substrate width and the static friction coefficient to 650 N / m or less.

[0120] In particular, it is known that by setting the product of the tension relative to the width of the substrate and the coefficient of static friction to 650 N / m or less, the generation of wrinkles can be further suppressed.

[0121] [Table 1]

[0122]

[0123] [Table 2]

[0124]

[0125] Industrial Applicability

[0126] As an application example of the present invention, an apparatus for performing vapor deposition of an alkali metal system can be cited.

[0127] Explanation of Reference Numerals

[0128] 10 Film Forming Apparatus

[0129] 11 Conveying Unit

[0130] 13 Film Forming Section

[0131] 16 Chamber

[0132] 111 Unwinding Roller

[0133] 112 Rewinding Roller

[0134] 113 Main Roller

[0135] 115, 116 Rollers

[0136] 131 Vapor Deposition Source

[0137] 133 Shield

[0138] 133a Opening

[0139] F Substrate

[0140] P1 Vacuum Pump

[0141] L Exhaust Line

Claims

1. A film forming apparatus, comprising: a transfer unit for transferring a substrate; and a film forming unit for forming Li metal on a film forming region of the substrate transferred by the transfer unit in a vacuum, the transfer unit includes a plurality of rollers, at least one of the plurality of rollers is an anti-wrinkle roller, the static friction coefficient between the anti-wrinkle roller and the Li metal measured in an atmosphere with a dew point of -40°C or lower exceeds 0.50 and is 2.50 or lower, the Young's modulus of the surface of the anti-wrinkle roller is 2.5 GPa or lower, the surface of the anti-wrinkle roller is made of polypropylene.

2. The film forming apparatus according to claim 1, wherein, The dynamic friction coefficient between the anti-wrinkle roller and the Li metal measured in an atmosphere with a dew point of -40°C or lower is 0.10 or higher and 1.20 or lower.

3. The film forming apparatus according to claim 1 or 2, wherein The surface free energy of the surface of the anti-wrinkle roller is 40 mN / m or lower.

4. A transfer method, using the anti-wrinkle roller to transfer the substrate in the film forming apparatus according to claim 1 or 2.

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