Atmospheric pressure plasma processing method and atmospheric pressure plasma processing apparatus

Abstract

To provide an atmospheric pressure plasma processing method and atmospheric pressure plasma processing apparatus, capable of introducing plasma formation gas from an inner passage passing between a pair of electrodes, between the pair of electrodes and a workpiece while relatively moving the workpiece and the pair of electrodes, and suppressing the reduction of a processing speed due to carrier gas when subjecting the workpiece to atmospheric pressure plasma processing to efficiently plasma-process the workpiece.SOLUTION: When setting a distance between a pair of electrodes and a workpiece to h, a relative travel speed between the pair of electrodes and the workpiece to U, the viscosity of gas existing between the pair of electrodes and the workpiece to μ, a gas pressure between the pair of electrodes and the workpiece to P and a position in the transportation direction of the workpiece to x, p*shown by the formula p*=(h2 / 2Uμ)(-dP / dx) satisfies 0<p*≤9.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a plasma processing method using atmospheric pressure plasma and an atmospheric pressure plasma processing apparatus for carrying out this processing method. [Background technology]

[0002] 2. Description of the Related Art Atmospheric pressure plasma processing is known in which plasma is generated under atmospheric pressure (or near atmospheric pressure) to process any processing target (workpiece) such as a substrate. For example, in atmospheric pressure plasma film formation, a plasma generating gas such as an inert gas is introduced between electrodes to generate plasma, and this plasma activates a source gas containing film forming materials introduced through a flow path different from the flow path between the electrodes. In atmospheric pressure plasma film formation, activated species of the film forming material thus obtained are attached to the workpiece to form a film.

[0003] This atmospheric pressure plasma treatment is performed under atmospheric pressure, so there is no need for expensive vacuum vessels such as vacuum chambers, which has the advantage of reducing equipment costs, and it also has the advantage of being able to treat workpieces that are difficult to treat under vacuum.

[0004] On the other hand, a method that can efficiently perform processes such as film formation on a workpiece is known as roll-to-roll, in which a long workpiece wound in a roll is fed out in the longitudinal direction and processed while being wound up. In the following explanation, roll-to-roll is also referred to as "RtoR" for convenience.

[0005] From the viewpoint of productivity, it is conceivable to utilize RtoR in atmospheric pressure plasma processing as well. For example, Patent Document 1 describes an atmospheric pressure plasma processing apparatus using a RtoR method for performing plasma processing on the surface of a substrate (workpiece), which has an atmospheric pressure plasma processing chamber for performing atmospheric pressure plasma processing, and a front chamber and a rear chamber connected to the front and rear of the atmospheric pressure plasma processing chamber via a substrate transport opening provided in the atmospheric pressure plasma processing chamber, and is equipped with an adjustment mechanism that varies the volume using partition plates installed in the front chamber and the rear chamber. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-185494 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, atmospheric pressure plasma does not require an expensive vacuum vessel such as a vacuum chamber, and can also process workpieces that are difficult to process in a vacuum. Furthermore, by using RtoR, atmospheric pressure plasma processing with these advantages becomes possible with more efficient processing. Moreover, atmospheric pressure plasma does not require transporting the workpiece inside a vacuum chamber, making RtoR easy to use.

[0008] However, when atmospheric pressure plasma treatment is performed while transporting a workpiece, as in the case of RtoR, the inventors have found that the faster the workpiece transport speed, the more significant the decrease in treatment speed due to the ambient gas (hereinafter referred to as the "accompanying gas") that is entrained on the workpiece surface as the workpiece is transported, which causes a manufacturing problem. In this case, the ambient gas includes not only gases that are already present in the space, but also plasma generating gases and raw material gases supplied from any flow path. The same problems caused by the entrained gas occur when atmospheric pressure plasma processing is performed with the workpiece fixed and the electrode moved.

[0009] Since the accompanying gas is often inactive, it deactivates the generated plasma and activated species. In addition, the accompanying gas acts as an impurity in the target process, inhibiting the diffusion of the generated plasma and activated species and their reaction with the workpiece surface. Therefore, if an accompanying gas is generated, the activated species including the plasma reaching the workpiece surface will be insufficient, leading to a decrease in processing efficiency.

[0010] When performing atmospheric pressure plasma treatment while transporting a workpiece, such as in roll-to-roll treatment, the faster the workpiece is transported, the more efficient the treatment can be. However, the faster the workpiece transport speed, the more gas is entrained, and the greater the decrease in processing speed due to the entrained gas.

[0011] The object of the present invention is to provide an atmospheric pressure plasma processing method that enables highly efficient processing by suppressing a decrease in processing speed caused by accompanying gas when processing a workpiece, such as a substrate, by atmospheric pressure plasma while moving the workpiece relative to an electrode using RtoR or the like, and an atmospheric pressure plasma processing apparatus for implementing this atmospheric pressure plasma processing method. [Means for solving the problem]

[0012] In order to achieve the above-mentioned object, the present invention has the following configuration. [1] When the electrode pair and the workpiece are moved relative to each other and a plasma generating gas is introduced between the electrode pair and the workpiece from the inner flow path passing between the electrode pair to process the workpiece with atmospheric pressure plasma, the distance between the electrode pair and the workpiece is h, the relative movement speed between the workpiece and the electrode pair is U, the viscosity of the gas between the electrode pair and the workpiece is μ, the gas pressure between the electrode pair and the workpiece is P, and the position of the workpiece in the relative movement direction with respect to the electrodes is x. The expression ``p * =(h 2 / 2Uμ)·(-dP / dx)』 p shown by * But, 0 <p *An atmospheric pressure plasma treatment method that satisfies ≦9. [2] The atmospheric pressure plasma processing method according to [1], wherein a region is provided between the electrode pair and the workpiece, in which gas flows in a direction opposite to the direction of relative movement of the workpiece with respect to the electrode pair. [3] The atmospheric pressure plasma processing method according to [1] or [2], further comprising introducing a plasma generating gas from at least one of an upstream flow path located upstream of the inner flow path in the direction of relative movement of the workpiece with respect to the electrode pair, and a downstream flow path located downstream of the inner flow path in the direction of relative movement of the workpiece with respect to the electrode pair. [4] The atmospheric pressure plasma processing method according to [3], wherein a source gas for forming a film on the workpiece is introduced from at least one of the upstream flow path and the downstream flow path. [5] By increasing the amount of gas introduced from the downstream flow path compared to the amount of gas introduced from the upstream flow path, * to 0 <p * The atmospheric pressure plasma processing method according to [3] or [4], wherein the ρ is ≦9. [6] By making the area of ​​the gas outlet of the upstream flow path and the area of ​​the gas outlet of the downstream flow path different, p * to 0 <p * The atmospheric pressure plasma processing method according to any one of [3] to [5], wherein the temperature is ≦9. [7] By making the shape of the surface of the electrode that forms the electrode pair that faces the workpiece different on the upstream flow path side and the downstream flow path side, p * to 0 <p * The atmospheric pressure plasma processing method according to any one of [3] to [6], wherein the temperature is ≦9. [8] By providing an air supply means downstream of the inner flow path in the direction of relative movement of the workpiece with respect to the electrode pair and supplying air from the air supply means, * to 0 <p * The atmospheric pressure plasma processing method according to any one of [1] to [7], wherein the temperature is ≦9. [9] By providing an exhaust means upstream of the inner flow path in the relative movement direction of the workpiece with respect to the electrode pair and exhausting from the exhaust means, p * to 0 <p *The atmospheric pressure plasma processing method according to any one of [1] to [8], wherein the temperature is ≦9.

[10] an electrode pair; a moving means for relatively moving the workpiece and the electrode pair along a path facing the electrode pair; an inner flow passage that passes between the electrode pair and introduces a gas between the electrode pair and the workpiece; When the distance between the electrode pair and the workpiece is h, the relative movement speed between the electrode pair and the workpiece is U, the viscosity of the gas between the electrode pair and the workpiece is μ, the gas pressure between the electrode pair and the workpiece is P, and the position of the workpiece in the relative movement direction with respect to the electrode pair is x, * =(h 2 / 2Uμ)·(-dP / dx) * But, 0 <p * and a gas flow control means for controlling the gas flow between the electrode pair and the workpiece so as to satisfy ≦9.

[11] Furthermore, an upstream flow path that introduces gas between the electrode pair and the workpiece, upstream of the inner flow path in the relative movement direction of the workpiece with respect to the electrode pair; and

[10] An atmospheric pressure plasma processing apparatus according to

[10] , having a downstream flow path that introduces gas between the electrode pair and the workpiece, downstream of the inner flow path in the direction of relative movement of the workpiece with respect to the electrode pair. [Effects of the Invention]

[0013] According to the present invention, when the workpiece is treated with atmospheric pressure plasma while the workpiece and the electrode pair are moved relative to each other using RtoR or the like, the decrease in treatment speed caused by the accompanying gas can be suppressed, and highly efficient treatment can be achieved. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram conceptually showing an example of an atmospheric pressure plasma processing apparatus of the present invention for carrying out an example of an atmospheric pressure plasma processing method of the present invention. [Figure 2] 10 is a graph showing an example of the relationship between the workpiece transport speed and the film formation speed. [Figure 3]FIG. 2 is a conceptual diagram for explaining a gas flow. [Figure 4] 10 is a graph showing an example of a gas flow between an electrode pair and a workpiece. [Figure 5] 1 is a graph showing the relationship between p* and film formation rate in an example. [Figure 6] FIG. 1 is a conceptual diagram for explaining atmospheric pressure plasma film formation by a remote diffusion mixing method. DETAILED DESCRIPTION OF THE INVENTION

[0015] The atmospheric pressure plasma processing method and atmospheric pressure plasma processing apparatus of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

[0016] The following description of the constituent elements will be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. The drawings shown below are conceptual diagrams for explaining the present invention, and therefore the sizes, lengths, positional relationships, etc. of the components do not necessarily correspond to the actual objects.

[0017] FIG. 1 conceptually shows an example of an atmospheric pressure plasma film forming apparatus that uses the atmospheric pressure plasma processing apparatus of the present invention to form a film on a workpiece by the atmospheric pressure plasma processing method of the present invention. The atmospheric pressure plasma processing method of the present invention is not limited to forming a film on a workpiece, and may be used to perform various types of plasma processing on workpieces, such as activating the surface of a workpiece with plasma. Furthermore, the atmospheric pressure plasma processing apparatus of the present invention is not limited to a film formation apparatus, but may be a processing apparatus that only processes workpieces using plasma. In this case, the processing apparatus does not need to have the upstream and downstream flow paths described below. Of course, the atmospheric pressure plasma processing of the present invention may be performed using the atmospheric pressure plasma film formation apparatus shown in FIG.

[0018] In the present invention, the workpiece is any object to be treated by atmospheric pressure plasma treatment, and includes all objects that can be subjected to various treatments by atmospheric pressure plasma while moving relative to the electrode. Therefore, the workpiece may be not only a sheet-shaped (plate-shaped, film-shaped, membrane-shaped) substrate but also a base material of any shape. Also, the substrate may be not only a long substrate corresponding to the RtoR described below but also a cut sheet (single-leaf type).

[0019] Furthermore, in the following description, the workpiece and the electrode pair are moved relatively by fixing the electrode pair and transporting the workpiece, but the present invention is not limited to this. That is, in the plasma processing method and plasma processing apparatus of the present invention, the workpiece and the electrode pair may be moved relative to each other by fixing the workpiece and moving the electrode pair, or the workpiece and the electrode pair may be moved relative to each other by moving both the workpiece and the electrode pair. Note that the movement (transport) of the electrode pair in this case may be performed by a known method depending on the size, configuration, and shape of the electrode pair.

[0020] The atmospheric pressure plasma film formation apparatus 10 shown in Figure 1 is an apparatus for performing atmospheric pressure plasma film formation. Atmospheric pressure plasma film formation involves, for example, depositing any active species onto a workpiece using atmospheric pressure plasma processing to form a film. An example of an atmospheric pressure plasma film formation method is a method in which a plasma-generating gas such as an inert gas is introduced between electrodes to generate plasma, and this plasma activates a source gas containing a film-forming material that is introduced through a flow path different from the flow path between the electrodes. 1 is an example of an atmospheric pressure plasma film formation apparatus 10 that forms a film on a workpiece Z using remote diffusion mixing atmospheric pressure plasma (atmospheric pressure plasma CVD (Chemical Vapor Deposition)), in which plasma generation and contact between the plasma and a raw material gas are performed in separate locations. The atmospheric pressure plasma film formation apparatus 10 also utilizes the above-mentioned RtoR, and forms a film on the long workpiece Z using atmospheric pressure plasma while transporting the workpiece Z in the longitudinal direction. Therefore, the atmospheric pressure plasma film forming apparatus 10 introduces the raw material gas and the plasma generating gas separately under atmospheric pressure (or near atmospheric pressure), and mixes the raw material gas with the plasma generated between the electrode pair between the electrode pair and the transported workpiece Z. This activates the raw material gas with the plasma, and a film is formed on the workpiece Z using the activated raw material gas (activated species).

[0021] Specifically, as shown conceptually in Fig. 6, an example of a typical configuration, in a remote diffusion mixing type atmospheric pressure plasma film formation apparatus, a plasma generating gas PG is introduced into an inner flow path between an electrode pair 100 to generate plasma, which is then introduced between the electrode pair 100 and the workpiece Z. In addition, a source gas MG is introduced between the electrode pair and the workpiece Z from outer flow paths 102a and 102b provided outside the inner flow path. In this way, the plasma generated between the electrode pair 100 comes into contact with and mixes with the source gas between the electrode pair and the workpiece Z, thereby forming a film on the workpiece Z. Here, in the present invention, a film is formed on the workpiece Z while the workpiece Z is transported, for example, in the direction of arrow a. Therefore, in the apparatus shown in Fig. 6, the outer flow path 102a corresponds to the upstream flow path in the present invention, and the outer flow path 102b corresponds to the downstream flow path in the present invention. In the following description, the atmospheric pressure plasma film forming apparatus will also be simply referred to as a film forming apparatus.

[0022] In the present invention, there are no restrictions on the material of the workpiece Z (object to be processed) on which a film is formed, and various known workpieces that can be formed with atmospheric pressure plasma and preferably by roll-to-roll can be used. For example, in the case of a sheet-like workpiece Z (substrate to be processed) as shown in the example, examples include resin films (polymer films, plastic films) made of polymer materials such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene, polypropylene, polystyrene, polyamide, polyvinyl chloride, polycarbonate, polyacrylonitrile, polyimide, polyacrylate and polymethacrylate, as well as silicon, etc.

[0023] Furthermore, there are no limitations on the film to be formed on the workpiece Z, and various known materials that can be formed by atmospheric pressure plasma film formation can be used. Examples include gas barrier films such as silicon oxide, silicon oxynitride, silicon nitride, and aluminum oxide; light reflective films and anti-reflective films such as silicon oxide, titanium oxide, zinc oxide, tin oxide, and fluorine compounds; transparent conductive films such as indium tin oxide, tin oxide, indium oxide, zinc oxide, indium-cadmium oxide, cadmium-tin oxide, cadmium oxide, and gallium oxide; and DLC (Diamond Like Carbon) films.

[0024] Furthermore, various known raw material gases and plasma generating gases can be used depending on the film to be formed. The raw material gas is a gas containing components that will become the film to be formed, and the plasma generating gas is a gas for generating plasma. For example, when depositing a DLC film, examples of the source gas include hydrocarbon gases such as methane gas, propane gas, and acetylene gas, and examples of the plasma generating gas include argon gas. When depositing a silicon oxide film, examples of the source gas include TEOS (tetraethoxysilane) gas, and examples of the plasma generating gas include nitrogen gas.

[0025] The film forming apparatus 10 shown in FIG. 1 includes a cylindrical electrode 12, a film forming unit 14, an AC power supply 16, a drum 18, and a touch roll 19. In FIG. 1, the cylindrical electrode 12, the film-forming unit 14, the drum 18, and the touch roll 19 are shown in cross section, but hatching has been omitted to simplify the drawing and clearly show the configuration of the film-forming apparatus 10. In the following description, for convenience, the position of each member will be expressed as up, down, and side (right and left) according to Fig. 1. However, these up-down directions (top-bottom directions) and side (horizontal directions) do not necessarily coincide with the actual state of use of the film forming apparatus 10.

[0026] The film forming apparatus 10 transports a long workpiece Z by wrapping it around a drum 18, and while positioning the workpiece Z at a predetermined film forming position and transporting it in the longitudinal direction, forms a film on the surface of the workpiece Z using atmospheric pressure plasma using a cylindrical electrode 12, a film forming unit 14, and an AC power source 16. In the following description, unless otherwise specified, upstream and downstream refer to the upstream and downstream in the transport direction of the workpiece Z. In a preferred embodiment, a touch roll 19 is provided upstream of the film-forming unit 14 to sandwich the workpiece Z together with the drum 18, thereby shielding the workpiece Z from the gas accompanying the workpiece Z.

[0027] There are no restrictions on the drum 18, and various known drums (cans) can be used that are used to wrap the workpiece Z around them and transport it longitudinally while positioning it in a predetermined position during processing of the workpiece Z, such as film formation using RtoR. In the present invention, the means for transporting the workpiece at the film-forming position is not limited to a drum, and various known methods for transporting sheet-like objects can be used, such as a method using nip rolls as described in Patent Document 1, a method using a belt conveyor, or a method using a moving stage. However, the drum 18 shown in the figure is preferably used because it can stably hold and transport the workpiece in a predetermined position even when transporting at high speed.

[0028] There are no restrictions on the touch roll 19, and any known touch roll used in known devices for processing long workpieces (webs) can be used as long as it can come into contact with the transported workpiece Z, rotate in sync with the workpiece Z, and block the accompanying gas that moves with the workpiece Z. Therefore, there are no restrictions on the materials from which the drum 18 and the touch roll 19 are made, but from the viewpoint of adhesion between the drum 18 and the touch roll 19, it is preferable that the surfaces have different hardness, such as one surface being made of rubber, resin, or the like and the other surface being made of metal. When the surface of either the drum 18 or the touch roll 19 is made of rubber, resin, or the like, the entire body may be made of resin, or the surface of a metal body may be covered with rubber, resin, or the like.

[0029] In addition, in the present invention, there are no restrictions on the method of transporting the workpiece Z, and various known methods of transporting sheet-like objects (films, plate-like objects) can be used as long as they can transport the workpiece Z at the desired transport speed. This also applies to the case where the workpiece is a substrate of any shape.

[0030] The cylindrical electrode 12 is a cylindrical electrode whose height direction (axial direction) is perpendicular to the plane of the paper in Fig. 1. There are no limitations on the cylindrical electrode 12, and various known cylindrical electrodes used in atmospheric pressure plasma film formation by so-called dielectric barrier discharge can be used. An example of the cylindrical electrode 12 is an electrode in which the surface of a cylinder made of a conductive material such as metal is covered with a dielectric material such as quartz glass.

[0031] The film forming unit 14 is a block-shaped member made of metal. A flow path forming section 20 is provided in the lower center of the film forming unit 14 in the horizontal direction. The flow path forming section 20 is a cylindrical space with an inner diameter larger than the outer diameter of the cylindrical electrode 12, and the height direction is perpendicular to the plane of the paper. The lower end of the flow path forming section 20 opens from the lower end of the film forming unit 14. That is, the film forming unit 14 has a slit-shaped outlet 20a at the lower center in the transport direction of the workpiece Z, with the longitudinal direction being perpendicular to the transport direction of the workpiece Z, i.e., the width direction of the workpiece Z, A plasma generating gas supply path 24 is provided penetrating from the upper end of the flow path forming portion 20 to the upper surface of the film forming unit 14. A plasma generating gas supply source (not shown) is connected to the plasma generating gas supply path 24.

[0032] In the film forming apparatus 10, the cylindrical electrode 12 and the film forming unit 14 form an electrode pair for atmospheric pressure plasma. Therefore, the space between the cylindrical electrode 12 and the film forming unit 14 (the inner wall surface of the flow path forming portion 20) forms an inner flow path for introducing a plasma generating gas. Therefore, the plasma generation gas is converted into plasma by dielectric barrier discharge while passing through the inner flow path between the cylindrical electrode 12 and the film formation unit 14 from the plasma generation gas supply path 24, and is introduced into between the electrode pair and the workpiece Z from the outlet 20a on the bottom surface of the film formation unit 14. In other words, the outlet 20a is an outlet for gas from the inner flow path.

[0033] The film forming unit 14 is provided with an upstream source gas supply channel 26 and a downstream source gas supply channel 28, which are arranged to sandwich the flow path forming part 20 in the horizontal direction in the figure. The upstream source gas supply channel 26 and the downstream source gas supply channel 28 are both cylindrical spaces whose height direction is perpendicular to the plane of the drawing. The upstream source gas supply line 26 and the downstream source gas supply line 28 are both connected to a source gas supply source (a mixed gas of a source gas and a plasma generating gas) (not shown).

[0034] The film forming unit 14 is further provided with an upstream flow path 30 and a downstream flow path 32 so as to be located outside the inner flow path with respect to the transport direction of the workpiece Z. Specifically, the upstream flow path 30 is located upstream of the inner flow path, and the downstream flow path 32 is located downstream of the inner flow path. That is, the upstream flow path 30 is located upstream of the inner flow path in the relative movement direction of the workpiece Z with respect to the electrode pair, and the downstream flow path 32 is located downstream of the inner flow path in the relative movement direction of the workpiece Z with respect to the electrode pair. The upstream flow path 30 communicates with the upstream source gas supply path 26 to an outlet 30a on the bottom surface of the film forming unit 14. The outlet 30a is located upstream of the outlet 20a of the inner flow path. The outlet 30a is a slit-shaped opening having a longitudinal direction perpendicular to the width direction of the workpiece Z, i.e., the transport direction of the workpiece Z. The downstream flow path 32 communicates with the downstream source gas supply path 28 to an outlet 32a on the bottom surface of the film forming unit 14. The outlet 32a is located downstream of the outlet 20a of the inner flow path. The outlet 32a is a slit-shaped opening whose longitudinal direction is in the width direction of the workpiece Z. The lengths of the slits of the outlet 20a of the inner flow path described above, as well as the outlet 30a of the upstream flow path 30 and the outlet 32a of the downstream flow path 32, may all be set appropriately depending on the width of the workpiece Z on which film formation is intended to be performed.

[0035] As described above, in the illustrated example, a film is formed on the workpiece Z while the workpiece Z is being transported. Here, in the remote diffusion mixing type atmospheric pressure plasma film formation, gas flow paths (exhaust ports) for introducing raw material gases are usually provided on either side of the inner flow path (exhaust port 20a) in the workpiece transport direction. Therefore, in the film forming apparatus 10, as a preferred embodiment, the outlet 30a of the upstream flow path 30 and the outlet 32a of the downstream flow path 32 are arranged to sandwich the outlet 20a of the inner flow path in the transport direction of the workpiece Z. Also, as described above, as a preferred embodiment, the outlet 20a of the inner flow path, the outlet 30a of the upstream flow path 30, and the outlet 32a of the downstream flow path 32 are each slit-shaped with its longitudinal direction perpendicular to the transport direction of the workpiece Z.

[0036] The atmospheric pressure plasma processing method and atmospheric pressure plasma processing apparatus of the present invention are not limited to using a cylindrical electrode as in the film forming apparatus 10 shown in FIG. That is, the present invention provides the following p * to 0 <p * As long as it is possible to achieve a value of ≦9, various known atmospheric pressure plasma film formation techniques can be used, such as a configuration in which the space between two flat plate electrodes is used as an inner flow path and which has an upstream flow path and a downstream flow path located upstream and downstream of the flat plate electrodes, as shown in Patent Document 1 mentioned above, and a configuration as shown in Figure 6. Here, the flat electrode has corners. Therefore, if the electrode and the workpiece are brought close to each other, there is a possibility that abnormal discharge may occur. In contrast, the cylindrical electrode has no corners, so even if the electrode and the workpiece are brought close to each other, there is an extremely low possibility that abnormal discharge may occur. Considering this point, in the present invention, it is preferable to use a cylindrical electrode 12 such as the film forming apparatus 10 shown in the illustration, rather than a flat electrode.

[0037] In the film forming apparatus 10, an AC power supply 16 is connected to the cylindrical electrode 12. Furthermore, the film forming unit 14, which forms an electrode pair with the cylindrical electrode 12, is grounded. Therefore, by applying an AC voltage to the cylindrical electrode 12, a dielectric barrier discharge occurs between the cylindrical electrode 12 and the film formation unit 14 (the inner wall surface of the flow path forming part 20). This excites the plasma generation gas flowing between the cylindrical electrode 12 and the film formation unit 14, which is the inner flow path, and generates plasma.

[0038] The AC power supply 16 is a known high frequency AC power supply used for atmospheric pressure plasma film formation. In the present invention, there are no limitations on the frequency (frequency of plasma excitation power) and output (plasma excitation power) of the AC power supply 16, and they may be set appropriately depending on the film to be formed, the raw material gas and the plasma generating gas, the desired film formation rate, etc. In the present invention, a pulse power supply may be used in place of the AC power supply.

[0039] 1, when forming a film on the workpiece Z, an AC voltage is applied to the cylindrical electrode 12, as in the known remote diffusion mixing type atmospheric pressure plasma film formation, and a plasma generation gas is supplied between the cylindrical electrode 12, which is the inner flow path, and the film formation unit 14 (the inner wall surface of the flow path forming portion 20). This excites the plasma generation gas passing through the inner flow path to generate plasma, and the plasma generation gas containing plasma is introduced from the outlet 20a between the electrode pair and the workpiece Z. In the film formation apparatus 10, the cylindrical electrode 12 and the film formation unit 14 form an electrode pair as described above. In parallel, raw material gas (a mixed gas of raw material gas and plasma generating gas) is supplied to the upstream flow path 30 and the downstream flow path 32, and the raw material gas is introduced between the electrode and the workpiece Z from the exhaust port 30a and the exhaust port 32a. As a result, the plasma and the source gas are diffused and mixed between the electrode pair and the workpiece Z, the source gas is activated, and a film is formed on the workpiece Z by the activated species of the source gas that are generated.

[0040] In the illustrated film forming apparatus 10, there are no limitations on the flow rate of the plasma generating gas introduced from the inner flow path and the flow rates of the gas introduced from the upstream flow path 30 and the downstream flow path 32, and they may be set appropriately depending on the type of gas used, the desired film forming speed, the transport speed of the workpiece Z, etc. In the following description, the plasma generating gas may also be simply referred to as plasma gas. A mixed gas obtained by mixing a raw material gas and a plasma gas is usually introduced from the upstream flow path 30 and the downstream flow path 32. There are no limitations on the ratio of the amounts of the raw material gas and the plasma gas in this mixed gas, and it may be set appropriately depending on the type of gas used, the target film formation rate, the transport speed of the workpiece Z, etc.

[0041] Here, in the film formation apparatus 10 (film formation method) of the present invention, when the distance between the electrode pair and the workpiece Z is h, the transport speed of the workpiece Z is U, the viscosity of the gas existing between the electrode pair and the workpiece Z is μ, the gas pressure between the electrode pair and the workpiece Z is P, and the position of the workpiece Z in the transport direction is x, The expression ``p * =(h 2 / 2Uμ)·(-dP / dx)』 p shown by * But, 0 <p * Satisfying ≦9, By having such a configuration, the present invention suppresses a decrease in the film formation rate (processing rate) due to the accompanying gas generated by the transportation of the workpiece Z, and enables highly efficient film formation (plasma processing) using atmospheric pressure plasma.

[0042] As described above, according to the inventor's investigations, when forming a film using atmospheric pressure plasma while transporting the workpiece Z, the transport of the workpiece Z generates an accompanying gas that moves as if pulling the atmosphere on the surface of the workpiece Z, and a layer of this accompanying gas is formed on the surface of the workpiece Z on which the film is being formed. As a result, the activated raw material gas cannot come into contact with the work Z, the accompanying gas deactivates the plasma and activated raw material gas, the diffusion of the plasma and raw material gas is hindered, and the plasma and raw material gas flow out of the film formation region, thereby reducing the time required to generate and react with activated species of the plasma and raw material gas, and slowing down the film formation rate. Furthermore, the faster the transport speed of the workpiece Z, the greater the decrease in the film formation speed. The film formation region is a region between the electrode pair and the workpiece Z where the plasma gas (plasma) and the raw material gas (active species of the raw material gas) come into contact with the workpiece Z.

[0043] FIG. 2 shows the change in film formation speed when the transport speed of the workpiece Z is changed from 1 to 200 m / min (m / min) in atmospheric pressure plasma film formation using the film formation apparatus shown in FIG. 2 is an example in which a DLC film was formed in the same manner as in the examples described below, except that the flow rate of the source gas from the downstream flow path 32 was kept constant at 6.7 L / min (liters / min) and the transport speed was changed. In addition, in FIG. 2, the film formation speed is normalized based on the film formation speed when the transport speed is 1 m / min.

[0044] As shown in Figure 2, due to the accompanying gas, the film formation rate decreases as the transport speed of the workpiece Z increases. For example, at a transport speed of 200 m / min, the film formation rate decreases to about 30% compared to when the transport speed is 1 m / min.

[0045] In contrast, in the present invention, * =(h 2 / 2Uμ)·(-dP / dx) * But, 0 <p * The gas flow between the electrode pair (cylindrical electrode 12) and the workpiece Z is controlled so as to satisfy the condition ≦9. Preferably, the gas flow between the cylindrical electrode 12 and the workpiece Z is controlled so that, in at least a portion between the electrode pair and the workpiece Z, a gas flow occurs in the opposite direction to the transport direction of the workpiece Z, i.e., from downstream to upstream. By having such a configuration, the present invention suppresses a decrease in the film formation rate due to the accompanying gas generated by the transport of the workpiece Z, and makes it possible to perform highly efficient film formation using atmospheric pressure plasma.

[0046] FIG. 3 conceptually shows the gas flow between the workpiece Z and the electrode pair when film formation is performed using atmospheric pressure plasma while the workpiece Z is being transported. In atmospheric pressure plasma deposition involving the transportation of workpiece Z, the gas flow between workpiece Z and the electrode pair can be approximated by the Couette-Poiseuille flow, which is the sum of the Couette flow caused by the transportation of workpiece Z (in the direction of arrow a), shown on the left side of Figure 3, and the Poiseuille flow caused by the introduction of gas, shown on the right side of Figure 3. In other words, the entrained gas is generated by the Couette flow.

[0047] where: The distance from the workpiece Z (processing object) to the electrode pair in the separation direction is y (hereinafter referred to as separation distance y), The distance (gap) between the electrode pair and the workpiece Z is h (hereinafter referred to as the gap distance h). The gas flow velocity at the separation distance y is u, The transport speed of the workpiece Z, i.e., the relative movement speed between the workpiece Z and the electrode pair, is U. The viscosity of the gas between the workpiece Z and the electrode pair is μ, The gas pressure between the electrode pair and the workpiece Z is P, The position of workpiece Z in the transport direction is x, When this is the case, the velocity distribution of the Couette-Poiseuille flow (steady state) between parallel plates is expressed by the following equation: u / U={1-y / h}-p * {y / h(1-y / h)} p * =(h 2 / 2Uμ)·(-dP / dx) When a plasma gas and a raw material gas are present between the workpiece Z (processing object) and the electrode pair, the viscosity μ of the gas present between the workpiece Z and the electrode pair is approximated by the viscosity of the representative composition of the mixed gas. The representative composition of the mixed gas is specifically the composition of the mixed gas according to the supply ratio of the plasma gas and the raw material gas supplied to the film formation unit, i.e., the composition of the mixed gas supplied to the film formation unit.

[0048] Here, by using the relative movement speed U between the electrode pair and the workpiece Z and the gap distance h between the electrode pair and the workpiece Z, the separation distance y from the workpiece Z in the separation direction between the electrode pair and the electrode pair, and the gas flow velocity u at the separation distance y can be made dimensionless (normalized). Correspondingly, in the following description, the velocity ratio u / U between the relative movement speed U of the workpiece Z with respect to the electrode pair and the gas flow velocity u is referred to as the dimensionless flow velocity. Also, the relative distance y / h, which is the separation distance y from the workpiece Z to the gap distance h between the electrode pair and the workpiece Z, is referred to as the dimensionless distance. Therefore, the above formula is p * The distribution of the gas flow between the electrode pair and the workpiece Z can be defined by the above. Therefore, p * By controlling the above, the gas flow between the processing object and the electrode pair can be controlled, and a decrease in the film formation rate due to the accompanying gas can be suppressed.

[0049] p * An example of the gas flow velocity distribution between the electrode pair and the workpiece Z is shown in Figure 4. Here, the horizontal axis represents the dimensionless flow velocity u / U, and the vertical axis represents the dimensionless distance y / h. For example, in Figure 4, * The gas flow velocity distribution indicated by =2.0 corresponds to the gas flow velocity distribution when a gas of approximately 2 L / min is flowed from the outlet 32a of the downstream flow path 32 in the film forming apparatus 10 shown in FIG. 1, with the workpiece Z transport speed set to 200 m / min, the distance between the electrode pair and the workpiece Z set to 0.5 mm, and the gas supply width (slit width of the outlet) in the width direction of the workpiece Z set to 60 mm. Here, the relative movement speed of the workpiece Z with respect to the electrode pair is defined as positive in the transport direction of the workpiece Z, i.e., from upstream to downstream, and negative in the opposite direction. Therefore, the position where the dimensionless distance y / h = 1 and the dimensionless flow velocity u / U = 0 is a state where there is no gas flow at all, and the region where the dimensionless flow velocity u / U < 0.0 is a region where the gas flow is in the opposite direction to the transport direction of the workpiece Z, i.e., a region where the gas flow is occurring in the negative (negative) direction relative to the transport direction of the workpiece Z.

[0050] As shown in Figure 4, p *Regardless of this, at the surface of workpiece Z, that is, at the position where the dimensionless distance y / h is 0.0, the dimensionless flow velocity u / U is 1.0 and the Couette flow dominates the gas flow. In addition, in the region close to the workpiece Z, i.e., the region where the dimensionless distance y / h is small, the gas flow is greatly influenced by the transport of the workpiece Z, i.e., the Couette flow. * Regardless of the above, the gas flow in the region where the dimensionless distance y / h is small is in the positive direction from upstream to downstream.

[0051] p * When the value is "0," the influence of the Poiseuille flow is completely absent, and only the Couette flow dominates the gas flow. Therefore, the Couette flow, i.e., the accompanying gas, reduces the plasma processing efficiency. For example, in the film formation apparatus 10 shown in FIG. 1, this corresponds to the case where the same amount (including 0) of gas is introduced from the upstream flow path 30 and the downstream flow path 32. p * When ρ is less than 0, the non-dimensional flow velocity becomes large on the positive side. Therefore, the Couette flow, i.e., the inflow of the entrained gas, cannot be suppressed, and the plasma processing efficiency further decreases. For example, in the film formation apparatus 10 shown in FIG. 1, this corresponds to the case where gas is introduced from the upstream flow path 30. In contrast, p * When exceeds 0, a region occurs where the dimensionless velocity approaches 0, and p * When exceeds 2, a region occurs where the dimensionless flow velocity u / U becomes negative. As mentioned above, the region where the dimensionless flow velocity u / U is negative is the region where a gas flow occurs from downstream to upstream in the opposite direction to the transport direction of the workpiece Z. In other words, in this region, the Poiseuille flow, which flows in the opposite direction to the transport direction of the workpiece Z, is thought to cancel out the Couette flow.

[0052] On the other hand, p * As p increases, the gas flow in the opposite direction to the transport direction of the substrate Z becomes stronger. * If the ratio exceeds 9, the gas flow in the direction opposite to the transport direction of the substrate Z becomes too strong, shortening the residence time of the plasma and source gas in the film formation region and, conversely, decreasing the film formation rate. Therefore, when film formation is performed using atmospheric pressure plasma while the substrate Z is being transported, * =(h 2 / 2Uμ)·(-dP / dx) * But, 0 <p * According to the present invention, which controls the gas flow between the electrode pair and the substrate Z so as to satisfy ≦9, the inflow of the accompanying gas generated by the transportation of the substrate Z into the film formation region is suppressed, and the accompanying gas is prevented from hindering contact between the source gas and the substrate Z, deactivating the plasma and activated source gas, and hindering diffusion of the plasma and source gas, etc., thereby making it possible to sufficiently ensure the generation time of activated species of the plasma and source gas and the reaction time of the activated species. As a result, according to the present invention, it is possible to suppress a decrease in the film formation rate due to the gas accompanying the transportation of the substrate Z, and to perform highly efficient film formation using atmospheric pressure plasma. Here, in the present invention, in order to suppress the inflow of the accompanying gas into the film formation region and to suitably suppress the adverse effects of the accompanying gas, it is more preferable that there is a region in the gas flow velocity distribution between the electrode pair and the substrate Z where the dimensionless flow velocity u / U is negative. That is, in the present invention, it is more preferable that there is a region between the electrode pair and the substrate Z where the gas flows in a direction opposite to the transport direction of the substrate Z, from downstream to upstream. In consideration of this point, p * is more preferably 2 or more. Considering the above points, p * is 2≦p * It is preferable to satisfy ≦6.

[0053] In addition, p * There are no limitations on the method for calculating the ratio, and various methods can be used. Preferred calculation methods include the following methods 1 and 2.

[0054] <Method 1> I. Measure the "gap distance h between the electrode pair and the workpiece," "width w of the gas supply flow path from the inner flow path in the direction perpendicular to the workpiece transport direction," "flow rate Q of the gas supplied from the inner flow path that flows in the opposite direction to the workpiece transport direction in the flow path cross section consisting of gap distance h and width w," and "workpiece transport speed U." If it is difficult to measure the gap distance h and width w, it is acceptable to measure the flow path cross-sectional area A consisting of gap distance h and width w. Furthermore, if gas is introduced from both the upstream and downstream flow paths, the gas flow rate Q is calculated by subtracting the "gas flow rate introduced from the upstream flow path" from the "gas flow rate introduced from the downstream flow path." From the relational expression described later, instead of the gas flow rate Q, the average flow velocity v of the gas supplied from the internal flow path flowing in the opposite direction to the transport direction of the workpiece Z in the flow path cross section consisting of the gap distance h and width w is appropriately measured. ave ' is also acceptable. In addition, the average flow velocity v ave As an example, the gas may be made to flow from the inner flow passage while the electrode pair and the workpiece are kept relatively stationary, and the flow rate may be measured using an anemometer, an airflow visualization device, or the like. The flow rate Q and flow velocity v are the flow rate and flow velocity of only the plane Poiseuille flow component. II. Relational formula 'p * =6Q / (hwU)=6Q / (AU)', so p * Ask for. Here, the above relational expression is based on the idea that the flow of gas introduced from the downstream side to the upstream side in the above flow channel cross section ideally forms a Poiseuille flow, and therefore the gas flow rate in a plane Poiseuille flow is theoretically Q = w h 3 ·(-dP / dx) / (12μ), p * =(h 2 This was obtained by utilizing the fact that ρ = 2Uμ(-dP / dx). v ave When using v ave = Q / A, so p * =6v ave / U p * can be obtained. <Method 2> I. The gas flow velocity at each position in the direction of separation between the electrode pair (cylindrical electrode 12) and the workpiece Z is measured using an airflow visualization device or the like. II. Based on the transport speed U of the workpiece Z and the gap distance h between the electrode pair and the workpiece Z, the relationship between the dimensionless distance y / h and the dimensionless flow velocity u / U is plotted. III. Based on the flow velocity distribution, p * Ask for In Method 1 and Method 2, the "workpiece transport direction" refers to the "direction of relative movement between the workpiece and the electrode pair," the "downstream to upstream side in the workpiece transport direction" refers to the "downstream to upstream side in the direction of relative movement of the workpiece with respect to the electrode pair," and the "workpiece transport speed U" refers to the "relative movement speed U between the electrode pair and the workpiece." The same applies to the above points in the following explanations.

[0055] p * As mentioned above, the calculation method for p * =6v ave / U' is also available. As before, The distance from the workpiece Z in the direction of separation between the workpiece and the electrode pair is y. The gap distance between the electrode pair and the workpiece Z is h. The gas flow velocity at the separation distance y is u, The workpiece transport speed, i.e., the relative movement speed between the workpiece Z and the electrode pair, is U. The viscosity of the gas between the workpiece and the electrode pair is μ, The gas pressure between the electrode pair and the workpiece Z is P, The position of the workpiece in the transport direction is x, The width of the gas supply passage from the inner passage in the direction perpendicular to the workpiece transport direction is w, In the flow path cross section consisting of gap distance h and width w, the flow rate of the gas supplied from the internal flow path flowing in the opposite direction to the workpiece transport direction is Q. In the flow passage cross section consisting of gap distance h and width w, the average flow velocity of the gas supplied from the inner flow passage flowing in the opposite direction to the transport direction of the workpiece Z is v ave , The cross-sectional area of ​​the flow path consisting of the gap distance h and width w is defined as A. As mentioned above, the flow rate Q and the flow velocity v are the flow rate and the flow velocity of only the plane Poiseuille flow component.

[0056] As mentioned above, the velocity distribution of the Couette-Poiseuille flow (steady state) between parallel plates is expressed by the following equation: u / U={1-y / h}-p * {y / h(1-y / h)} Equation 1 p * =(h 2 / 2Uμ)·(-dP / dx)···Formula 2 On the other hand, the flow velocity distribution of Poiseuille flow (steady state) between parallel plates is expressed by the following equation. u=(h 2 / 2μ)·(-dP / dx){y / h(1-y / h)}

[0057] Here, when considering the gas flow rate Q in Poiseuille flow, it becomes as follows.

number

[0058] Therefore, from the above equation 2, p * can be expressed as follows: Q=(hwU / 6)(h 2 / 2Uμ)·(-dP / dx)=(hwU / 6)p * p * =6Q / hwU=6(Q / AU)=6(v ave / U) In addition, A and v ave may use the following relationship: A=hw v ave =Q / A That is, p * is considered to be six times the non-dimensional average flow velocity of the gas (forming Poiseuille flow) supplied from the internal flow path flowing from downstream to upstream in the flow path cross section consisting of the gap distance h, width, and w described above. From the above points, the above formula (1) can also be expressed as follows. u / U = {1 - y / h} - 6(y / h)(1 - y / h)(v ave / U)

[0059] In the present invention, there is no limitation on the conveyance speed of the workpiece Z, and it may be appropriately set according to the required productivity, the type of film to be formed, the type of gas used, and the like. Here, as shown in FIG. 2, in the atmospheric pressure plasma film formation involving the conveyance of the workpiece Z, the decrease in the film formation speed increases as the conveyance speed of the workpiece Z increases. In other words, the effect of the present invention is preferably obtained as the conveyance speed of the workpiece Z increases. On the other hand, as the relative speed U of the workpiece Z with respect to the electrode pair increases, the gas flow between the electrode pair and the workpiece Z becomes turbulent, and it becomes difficult to handle the gas flow as the above-described "quiescent Poiseuille flow (steady state)". That is, p * It becomes difficult to discuss in terms of. Also, the gas turbulence tendency changes depending on the gap distance h between the electrode pair and the substrate Z, the width w of the gas supply flow path from the inner flow path in the direction orthogonal to the conveyance direction (relative movement direction) of the workpiece Z, and the viscosity μ and density ρ of the gas existing between the electrode pair and the substrate Z. Similarly, p * There may be cases where it becomes difficult to discuss in terms of. Considering this point, when using the hydraulic diameter D = 2hw / (h + w), in the present invention, there exists a suitable range of Reynolds number Re = ρUD / μ, and it is preferably about 0 < Re < 3000, and more preferably 0 < Re < 200k.

[0060] In the present invention, there is no limitation on the method of controlling the gas flow between the electrode pair, that is, the cylindrical electrode 12 and the workpiece Z so as to satisfy 0 < p * ≦ 9, and various flow rate control methods can be used. As an example, a method of making the flow rate of the gas introduced from the downstream side flow path 32 (discharge port 32a) (downstream side gas flow rate) larger than the flow rate of the gas introduced from the upstream side flow path 30 (discharge port 30a) (upstream side gas flow rate) is exemplified. According to this method, the gas flows from downstream to upstream, so that the inflow of the accompanying gas into the film forming region can be suppressed. <p * ≦9, and preferably generates a gas flow from downstream to upstream between the electrode pair and the work Z, thereby suppressing a decrease in the film formation rate due to accompanying gas and enabling highly efficient atmospheric pressure plasma film formation.

[0061] Another example of a method is to make the first gas flow rate and the second gas flow rate unequal by making the areas of the outlet 30a of the upstream flow path 30 and the outlet 32a of the downstream flow path 32 different while making the gas introduction rates from the upstream flow path 30 and the downstream flow path 32 equal. In the illustrated example, the widths of the slits are made different, thereby making the first gas flow rate and the second gas flow rate unequal. For example, the gas introduction rates are uniform, and the slit width of exhaust port 32a is made smaller than that of exhaust port 30a, so that the flow rate of gas introduced from exhaust port 32a becomes faster than the flow rate of gas introduced from exhaust port 30a. According to this method, as in the previous example, the gas flows from downstream to upstream, so the inflow of the accompanying gas into the film formation region can be suppressed. <p * ≦9, and preferably generates a gas flow from downstream to upstream between the electrode pair and the work Z, thereby suppressing a decrease in the film formation rate due to accompanying gas and enabling highly efficient atmospheric pressure plasma film formation.

[0062] Another example of such a method is to provide a gas supply means for supplying gas downstream of the inner flow path, and supply, for example, a film-like gas (curtain gas) from this gas supply means. For example, in the film forming unit 14, a gas film forming means is provided on the opposite side of the inner flow path of the downstream flow path 32, i.e., downstream of the downstream flow path 32, and a curtain gas is supplied toward the workpiece Z. This curtain gas blocks the flow of gas from the downstream flow path 32 toward the downstream (right side). According to this method, as in the previous example, the gas flows from downstream to upstream, so the inflow of the accompanying gas into the film formation region can be suppressed. <p *≦9, and preferably generates a gas flow from downstream to upstream between the electrode pair and the work Z, thereby suppressing a decrease in the film formation rate due to accompanying gas, and enabling highly efficient atmospheric pressure plasma film formation.

[0063] Another example of such a method is to provide an exhaust means upstream of the inner flow passage and exhaust the gas from this exhaust means. For example, in the film forming unit 14, an exhaust means is provided on the opposite side of the upstream flow passage 30 from the inner flow passage, that is, upstream of the upstream flow passage 30, and gas is exhausted from here. According to this method, as in the previous example, the gas flows from downstream to upstream, so the inflow of the accompanying gas into the film formation region can be suppressed. <p * ≦9, and preferably generates a gas flow from downstream to upstream between the electrode pair and the work Z, thereby suppressing a decrease in the film formation rate due to accompanying gas, and enabling highly efficient atmospheric pressure plasma film formation.

[0064] As yet another example method, the shape of the region of the electrode facing the workpiece Z may be made different between the upstream flow path 30 side and the downstream flow path 32 side. For example, in the film forming unit 14, the shape of the electrode surface in the area facing the workpiece Z is adjusted so that the distance between the film forming unit 14 on the upstream flow path 30 side and the workpiece Z on the downstream flow path 32 side is narrower than the distance between the film forming unit 14 on the upstream flow path 30 side and the workpiece Z. According to this method, as in the previous example, the gas flows from downstream to upstream, so the inflow of the accompanying gas into the film formation region can be suppressed. <p * ≦9, and preferably generates a gas flow from downstream to upstream between the electrode pair and the work Z, thereby suppressing a decrease in the film formation rate due to accompanying gas, and enabling highly efficient atmospheric pressure plasma film formation.

[0065] In the present invention, two or more of these methods are used in combination. <p * ≦9, and preferably a gas flow from downstream to upstream may be generated between the electrode pair and the workpiece Z. These methods can also be used in the configurations shown in Patent Document 1 and FIG.

[0066] The above description is an example in which the present invention is used for film formation using atmospheric pressure plasma, but as mentioned above, the present invention can also be suitably used for processing workpieces using atmospheric pressure plasma. That is, in the present invention, by replacing film formation (plasma film formation) with treatment (plasma treatment) in the above description, it is possible to obtain basically the same effects, such as improved treatment efficiency.

[0067] The atmospheric pressure plasma processing method and atmospheric pressure plasma processing apparatus of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments, and various improvements and modifications may be made without departing from the gist of the present invention. [Example]

[0068] The present invention will be described in more detail below with reference to specific examples of the present invention. However, the present invention is not limited to the following examples.

[0069] [Example] A DLC film was formed on the workpiece Z using the film forming apparatus 10 shown in FIG. Workpiece Z was a long PEN film with a width of 60 mm and a thickness of 4 μm.

[0070] The distance between the workpiece Z and the lowermost part of the cylindrical electrode 12 and the lower surface of the film forming unit 14 was set to 2 mm. The cylindrical electrode 12 used was a stainless steel cylinder with a diameter of 17 mm and a length of 60 mm, the surface of which was covered with quartz glass with a thickness of 1.5 mm. The film forming unit 14 was made of stainless steel. A cylindrical flow path forming part 20 was provided in the lateral center of the film forming unit 14 so as to be open downward. Furthermore, a plasma generating gas supply path 24 was formed so as to communicate with the flow path forming part 20. The cylindrical electrode 12 was inserted into the flow path forming section 20 with the center of the cylinder aligned. The distance between the cylindrical electrode 12 and the film forming unit 14 (the inner wall surface of the flow path forming section 20) was 1.5 mm. As described above, the space between the cylindrical electrode 12 and the film forming unit 14 forms the inner flow path. Therefore, the width of the inner flow path (slit width) is 1.5 mm. Furthermore, an upstream source gas supply channel 26 and an upstream flow channel 30, and a downstream source gas supply channel 28 and a downstream flow channel 32 were formed in the film forming unit 14. The slit widths of the exhaust port 30a of the upstream flow channel 30 and the exhaust port 32a of the downstream flow channel 32 were set to 0.5 mm. Furthermore, the areas of the upstream flow channel 30 and the downstream flow channel 32 facing the exhaust port were angled at an angle of 18° (162°) with respect to the horizontal. The lengths of the slits of the outlet 20a of the inner flow path, the outlet 30a of the upstream flow path 30, and the outlet 32a of the downstream flow path 32 were all 60 mm.

[0071] An AC power source 16 with a frequency of 27.12 MHz was connected to the cylindrical electrode 12 . In addition, the film forming unit 14 was grounded.

[0072] A film was formed on the workpiece Z using the film forming apparatus 10. A mixed gas of 99.1 vol% argon gas, 0.7 vol% nitrogen gas, and 0.2 vol% oxygen gas was supplied to the inner flow channel at a flow rate of 2.3 L / min. On the other hand, a mixed gas of 99 vol % argon gas and 1 vol % propane gas was supplied to the upstream flow passage 30 and the downstream flow passage 32. The output of the AC power supply 16 was set to 500W. The film formation atmosphere was at room temperature and atmospheric pressure. The workpiece transport speed was set to 200 m / min.

[0073] Under the above conditions, the amount of gas introduced from the upstream flow path 30 is kept constant at 6.7 L / min, and the amount of gas introduced from the downstream flow path 32 is set as follows: 6.7L / min, 10.9L / min, 16.2L / min, 22.7L / min, 30.7L / min, 42.7L / min, 46.7L / min, and 58.1 L / min, The conditions were changed to the above, and a DLC film was formed on workpiece Z.

[0074] For each gas introduction amount from the downstream side flow path 32, p * was calculated. As a result, the amount of gas introduced from the downstream flow path 32 is p for 6.7L / min * is 0, p at 10.9L / min * is 1.1, p at 16.2L / min * is 2.4, p for 22.7L / min * is 4, p for 30.7L / min * is 6, p for 42.7L / min * is 9, p at 46.7L / min * is 10, p at 58.1L / min * was 13.

[0075] The DLC film formed under each condition was measured using an ATR (attenuated total reflection) method. The film formation rate was calculated from the DLC film thickness for each gas introduction amount from the downstream flow path 32. The deposition rate and p * The relationship between the film deposition speed and the transfer speed is shown in Figure 5. The film deposition speed is normalized based on the film deposition speed at a transfer speed of 1 m / min in Figure 2 described above. As mentioned above, the example shown in FIG. 2 is an example in which a DLC film is formed in the same manner as in this embodiment, except that the gas introduction rate from the downstream flow path is kept constant at 6.7 L / min and the transport speed is changed. Therefore, when the gas introduction rate from the downstream flow path 32 in this embodiment is 6.7 L / min (p* = 0) and the case in which the conveying speed of the workpiece Z is 200 m / min in FIG. 2 have the same film formation conditions and results.

[0076] As shown in Figs. 2 and 5, p * When is 0, that is, when the gas introduction rates from the upstream and downstream flow paths are the same at 6.7 L / min, if the conveying speed of the workpiece Z is 200 m / min, the film formation speed drops to about 30% compared to when the conveying speed of the workpiece Z is 1 m / min. In contrast, p * By making p exceed 0, the film formation rate can be improved. * By setting is 2 to 6, the film formation speed can be improved to about 60% of the case where the transport speed of the work Z is 1 m / min. On the other hand, p * On the other hand, if p exceeds 9, * The deposition rate is lower than when p is 0. * It is believed that when the ratio exceeds 9, the gas flow from the downstream side to the upstream side increases, resulting in a decrease in the residence time of the plasma and activated source gas in the film formation region, and thus a decrease in film formation efficiency. From the above results, the effects of the present invention are clear. [Industrial Applicability]

[0077] The present invention can be suitably used for processing workpieces and forming films in the manufacture of various products. [Explanation of symbols]

[0078] 10 (Atmospheric pressure plasma) film deposition equipment 12 Cylindrical electrode 14 Film forming unit 16 AC power supply 20 Flow path forming section 20a,30a,32a outlet 24. Plasma generating gas supply path 26 Upstream raw material gas supply line 28 Downstream raw material gas supply line 30 Upstream flow path 32 Downstream flow path 100 electrode pairs 102a,102b Outer channel PG Plasma generating gas MG raw material gas Z Work

Claims

1. When processing the workpiece with atmospheric pressure plasma by introducing a plasma generating gas between the electrode pair and the workpiece from an inner flow path passing between the electrode pair while moving the electrode pair and the workpiece relatively, a source gas for forming a film on the workpiece is introduced from both an upstream flow path located upstream of the inner flow path in a relative movement direction of the workpiece with respect to the electrode pair, and a downstream flow path located downstream of the inner flow path in a relative movement direction of the workpiece with respect to the electrode pair; The amount of gas introduced from the downstream flow path is made larger than the amount of gas introduced from the upstream flow path, When the distance between the electrode pair and the workpiece is h, the relative movement speed between the workpiece and the electrode pair is U, the viscosity of the gas present between the electrode pair and the workpiece is μ, the gas pressure between the electrode pair and the workpiece is P, and the position of the workpiece in the relative movement direction with respect to the electrode is x, Formula 'p' ＊ = (h) 2 / 2Uμ)・(-dP / dx)』 p shown by ＊ However, 2≦p ＊ An atmospheric pressure plasma treatment method that satisfies ≦9.

2. 2. The atmospheric plasma processing method according to claim 1, wherein a region is provided between the electrode pair and the workpiece, in which gas flows in a direction opposite to a direction of relative movement of the workpiece with respect to the electrode pair.

3. 3. The atmospheric pressure plasma processing method according to claim 1, further comprising introducing a plasma generating gas from at least one of an upstream flow path located upstream of the inner flow path in the direction of relative movement of the workpiece with respect to the electrode pair, and a downstream flow path located downstream of the inner flow path in the direction of relative movement of the workpiece with respect to the electrode pair.

4. The gas outlet of the upstream flow path and the gas outlet of the downstream flow path are made different in area, ＊ 2≦p ＊ 4. The atmospheric pressure plasma processing method according to claim 1, wherein the value of the saturation temperature is ≦9.

5. The shapes of the surfaces of the electrodes forming the electrode pair that face the workpiece are different between the upstream flow path side and the downstream flow path side, thereby ＊ 2≦p ＊ 5. The atmospheric pressure plasma processing method according to claim 1, wherein the value of the saturation temperature is ≦9.

6. An air supply means is provided downstream of the inner flow path in the direction of relative movement of the workpiece with respect to the electrode pair, and air is supplied from the air supply means, thereby ＊ 2≦p ＊ 6. The atmospheric pressure plasma processing method according to claim 1, wherein the value of the saturation temperature is ≦9.

7. An exhaust means is provided upstream of the inner flow path in the direction of relative movement of the workpiece with respect to the electrode pair, and exhaust is performed from the exhaust means, thereby ＊ 2≦p ＊ 7. The atmospheric pressure plasma processing method according to claim 1, wherein the value of the surface tension is ≦9.

8. an electrode pair; a moving means for relatively moving the workpiece and the electrode pair along a path facing the electrode pair; an inner flow passage that passes between the electrode pair and introduces a gas between the electrode pair and the workpiece; an upstream flow path that introduces a gas between the electrode pair and the workpiece, the upstream flow path being located upstream of the inner flow path in a relative movement direction of the workpiece with respect to the electrode pair; a downstream flow path that introduces gas between the electrode pair and the workpiece downstream of the inner flow path in a relative movement direction of the workpiece with respect to the electrode pair, the downstream flow path having a gas introduction amount greater than the gas introduction amount from the upstream flow path; When the distance between the electrode pair and the workpiece is h, the relative movement speed between the electrode pair and the workpiece is U, the viscosity of the gas existing between the electrode pair and the workpiece is μ, the gas pressure between the electrode pair and the workpiece is P, and the position of the workpiece in the relative movement direction with respect to the electrode pair is x, ＊ = (h 2 / 2Uμ)・(-dP / dx)』 ＊ However, 2≦p ＊ and a gas flow control means for controlling the gas flow between the electrode pair and the workpiece so as to satisfy the relationship ≦9.

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