Oxidation-resistant treatment method for copper material and plasma treatment apparatus

Abstract

To provide an oxidation-resistant treatment method for a copper material and a plasma treatment apparatus that can improve the treatment efficiency of the copper material while preventing the oxidation of the copper material.SOLUTION: A copper material Cu is transported to a discharge space Fs, which is the space between a first electrode 21 arranged on one surface of a plate-shaped dielectric substrate 23 and a second electrode 27 arranged opposite the first electrode 21 via the dielectric substrate 23. While a reactive gas Ah containing hydrogen is supplied to the discharge space Fs, a pulse voltage with a power density of 3.1 W / cm2 or more is applied to the first electrode 21, and the copper material Cu is irradiated with plasma Pr generated in the discharge space Fs. By irradiating the copper material Cu with plasma Pr, the oxidation resistance of the copper material Cu is improved, and the copper material Cu with improved oxidation resistance can be directly subjected to a post-treatment process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for oxidation-resistant treatment of copper material and a plasma treatment apparatus. [Background technology]

[0002] Materials whose surfaces are partially made of copper or copper alloys (hereinafter referred to as "copper materials") are widely used in electrical components such as printed circuit boards. Copper materials are, for example, in the form of plates, thin films, or wires, and are bonded to other materials such as metal materials or resins to form electrical components.

[0003] The surface of such copper materials oxidizes during storage in air. If a copper oxide film is formed on the surface of the copper material due to oxidation, the adhesion between the copper material and other materials will be reduced during the process of bonding the copper material to other materials. Furthermore, when soldering or wire bonding is performed, the copper oxide film can cause a problem of reduced electrical connectivity in the copper material. Furthermore, the formation of a copper oxide film on the copper material can cause the surface of the copper material to discolor, impairing its aesthetic appearance.

[0004] A conventional oxidation-resistant treatment method for preventing oxidation in copper materials involves applying a rust inhibitor to the surface of the copper material. The rust inhibitors used in conventional oxidation-resistant treatments include organic rust inhibitors such as azoles, or inorganic rust inhibitors such as chromates (see, for example, Patent Document 1). Treating the surface of a copper material with a rust inhibitor can prevent the copper material from oxidizing while it is stored in a warehouse or the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-081354 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the conventional example having such a configuration has the following problems.

[0007] In conventional oxidation-resistant treatments, a rust inhibitor with oxidation resistance is generally applied to the surface of a copper material. When a post-treatment process, such as bonding the copper material to another material or heat-treating the copper material, is performed, the rust inhibitor applied to the surface of the copper material interferes with the post-treatment process. Therefore, a process for removing the rust inhibitor from the stored copper material is essential before the copper material is subjected to the post-treatment process. Performing such a rust inhibitor removal process increases the time and cost required for copper material treatment, thereby reducing the processing efficiency of the copper material.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide an oxidation-resistant treatment method for copper material and a plasma treatment apparatus that can prevent oxidation of the copper material while improving the treatment efficiency of the copper material. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention has the following configuration. That is, the present invention is a method for oxidation-resistant treatment of copper material using plasma, in which a reactive gas containing hydrogen is supplied and a power density is set to 3.1 W / cm 2 The present invention is characterized by comprising a plasma treatment process in which the copper material is irradiated with plasma generated under the above conditions.

[0010] (Operation and Effect) With this configuration, a reactive gas containing hydrogen can be supplied while the power density is kept at 3.1 W / cm. 2 By irradiating a copper material with plasma generated under the above conditions, the oxidation resistance of the copper material can be improved. In this case, the copper material with improved oxidation resistance can be directly subjected to a post-treatment process. Therefore, there is no need to remove an oxidation protection film, such as a rust inhibitor, before the post-treatment process, thereby improving the processing efficiency of the copper material.

[0011] In order to achieve the above object, the present invention may have the following configuration. That is, the present invention is a method for oxidation-resistant treatment of copper material using plasma, characterized by comprising a plasma treatment process in which plasma generated by applying a pulse voltage having a frequency of 20 kHz or more while supplying a reactive gas containing hydrogen is irradiated onto the copper material.

[0012] (Actions and Effects) According to this configuration, the oxidation resistance of copper materials can be improved by irradiating the copper materials with plasma generated by applying a pulse voltage with a frequency of 20 kHz or higher while supplying a reactive gas containing hydrogen. In this case, the copper materials with improved oxidation resistance can be directly subjected to post-treatment processes. Therefore, there is no need to remove an oxidation protection film, such as a rust inhibitor, before the post-treatment process, thereby improving the processing efficiency of copper materials.

[0013] In the above-described invention, it is preferable that the plasma treatment step irradiates the copper material with the plasma generated by a dielectric barrier discharge method.

[0014] (Actions and Effects) According to this configuration, the copper material is irradiated with plasma generated by the dielectric barrier discharge method. The dielectric barrier discharge method can generate highly uniform plasma over a wider area. This significantly improves the processing efficiency of the oxidation-resistant treatment of the copper material using plasma.

[0015] In the above-described invention, it is preferable that the plasma treatment step irradiates the copper material with the plasma while the copper material is being transported by a continuous treatment method.

[0016] (Actions and Effects) According to this configuration, the copper material being transported by a continuous treatment method is irradiated with the plasma. By transporting the copper material by a continuous treatment method and performing the plasma treatment process, the efficiency of plasma treatment on the copper material can be greatly improved compared to the conventional configuration in which the copper material is transported by a batch method and plasma treatment is performed. Therefore, the treatment efficiency of oxidation resistance treatment on the copper material can be greatly improved.

[0017] In order to achieve the above object, the present invention may have the following configuration. That is, the plasma processing apparatus according to the present invention includes a plate-shaped dielectric substrate, a first electrode disposed on one surface of the dielectric substrate, a second electrode disposed so as to face the first electrode with the dielectric substrate interposed therebetween, a gas supply unit that supplies a reactive gas containing hydrogen to a discharge space that is a space between the first electrode and the second electrode, and a pulse power supply that applies a pulse voltage to at least one of the first electrode and the second electrode, wherein at least a portion of the discharge space is configured to be always connected to the outside, and the pulse power supply has a power density of 3.1 W / cm 2 The present invention is characterized in that it is configured to apply a pulse voltage of at least this magnitude.

[0018] (Operation and Effect) With this configuration, a reactive gas containing hydrogen can be supplied while the power density is kept at 3.1 W / cm. 2 By irradiating a copper material with plasma generated under the above conditions, the oxidation resistance of the copper material can be improved. In this case, the copper material with improved oxidation resistance can be directly subjected to the post-treatment process. Therefore, there is no need to remove an oxidation protection film, such as a rust inhibitor, before the post-treatment process, thereby improving the processing efficiency of the copper material. In addition, the copper material is irradiated with plasma generated by a dielectric barrier discharge method using first and second electrodes equipped with dielectric substrates. The dielectric barrier discharge method can generate highly uniform plasma over a wider area. Therefore, the processing efficiency of the process of using plasma to perform oxidation resistance treatment on copper material can be greatly improved.

[0019] In order to achieve the above object, the present invention may have the following configuration. That is, the plasma processing apparatus according to the present invention comprises a plate-shaped dielectric substrate, a first electrode arranged on one side of the dielectric substrate, a second electrode arranged so as to face the first electrode via the dielectric substrate, a gas supply unit that supplies a reactive gas containing hydrogen to a discharge space that is the space between the first electrode and the second electrode, and a pulse power supply that applies a pulse voltage to at least one of the first electrode and the second electrode, wherein at least a portion of the discharge space is configured to be always connected to the outside, and the pulse power supply is configured to apply a pulse voltage having a frequency of 20 kHz or more.

[0020] (Actions and Effects) According to this configuration, the oxidation resistance of copper materials can be improved by irradiating the copper materials with plasma generated by applying a pulse voltage with a frequency of 20 kHz or higher while supplying a reactive gas containing hydrogen. In this case, the copper materials with improved oxidation resistance can be directly subjected to a post-treatment process. Therefore, there is no need to remove an oxidation protection film, such as a rust inhibitor, before the post-treatment process, thereby improving the processing efficiency of copper materials. In addition, the copper materials are irradiated with plasma generated by a dielectric barrier discharge method using first and second electrodes equipped with dielectric substrates. The dielectric barrier discharge method can generate highly uniform plasma over a wider area. Therefore, the processing efficiency of the process of performing oxidation resistance treatment on copper materials using plasma can be significantly improved. [Effects of the Invention]

[0021] According to the oxidation resistance treatment method and plasma treatment apparatus of the present invention, the oxidation resistance of copper material can be improved by irradiating the copper material with plasma generated under conditions of a predetermined power density or frequency or higher while supplying a hydrogen-containing reactive gas. In this case, the copper material with improved oxidation resistance can be directly subjected to a post-treatment process. Therefore, there is no need to remove an oxidation protection film, such as a rust inhibitor, before the post-treatment process, thereby improving the processing efficiency of the copper material. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a front view illustrating the overall configuration of a plasma processing apparatus according to an embodiment; [Figure 2] 1 is a perspective view illustrating a main part of a plasma processing apparatus according to an embodiment. [Figure 3] FIG. 10 is a front view illustrating a state in which the second divided body has moved to a processing position in the plasma processing apparatus according to the embodiment. [Figure 4] FIG. 2 is a front view illustrating a state in which plasma is generated in the plasma processing apparatus according to the embodiment. [Figure 5] FIG. 3 is a vertical cross-sectional view illustrating the configuration of a first divided body according to the embodiment. [Figure 6] 1A and 1B are diagrams illustrating Experiment 1 according to an embodiment, in which (a) is a plan view showing a copper material, (b) is a plan view showing operations on a first region and a second region of the copper material, (c) is an image showing the copper material after plasma treatment in a state before heat treatment, and (d) is an image showing the copper material after plasma treatment in a state after heat treatment. [Figure 7] FIG. 10 is a front view illustrating a state in which the second divided body has moved to an initial position in the plasma processing apparatus according to the modified example. [Figure 8] FIG. 10 is a front view illustrating a state in which the second divided body has moved to a processing position in the plasma processing apparatus according to the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram of a plasma processing apparatus 1 according to the embodiment. In this embodiment, the left-right direction in Fig. 1 is defined as the x-direction, the depth direction is defined as the y-direction, and the up-down direction is defined as the z-direction.

[0024] <Explanation of overall configuration> The plasma processing apparatus 1 according to the first embodiment includes a plasma generator 3, a substrate supply unit 5, and a substrate recovery unit 7. The plasma generator 3 generates plasma using power supplied from a pulse power supply 11, which will be described later. The substrate supply unit 5 supplies a substrate to be subjected to plasma processing to the plasma generator 3. In this embodiment, a copper material Cu is used as the substrate. In this embodiment, a thin film of copper (copper foil) is used as the copper material Cu. An example of the thickness of the copper material Cu, which is copper foil, is 0.002 mm to 3.2 mm. The substrate recovery unit 7 recovers the substrate irradiated with plasma in the plasma generator 3.

[0025] The plasma generator 3 includes a plasma reactor 9, a pulsed power supply 11, a gas supply unit 13, and a gas recovery unit 15. The plasma reactor 9 includes a first divided body 17 and a second divided body 19. As shown in FIG. 2, the first divided body 17 and the second divided body 19 are arranged facing each other with a gap therebetween.

[0026] The first divided body 17 is a rectangular parallelepiped member extending in the y direction as a whole. The first divided body 17 includes a first electrode 21 and a dielectric substrate 23. The first electrode 21 is embedded in the lower surface side of the first divided body 17. The first electrode 21 has a plate-like shape extending in the x and y directions. The dielectric substrate 23 is disposed below the first electrode 21. The dielectric substrate 23 is disposed so as to cover the lower surface of the first electrode 21. Like the first electrode 21, the dielectric substrate 23 has a plate-like shape extending in the x and y directions. The dielectric substrate 23 is made of a dielectric material, and examples of constituent materials include aluminum oxide (alumina) and quartz.

[0027] The second divided body 19 is a rectangular parallelepiped member extending in the y direction as a whole. The second divided body 19 includes a second electrode 27. The second electrode 27 is disposed on the upper surface of the second divided body 19. The second electrode 27 is a pair of cylindrical members extending in the y direction. The second electrode 27 is disposed parallel to the first electrode 21 so as to face each other. That is, the first electrode 21 and the second electrode 27 form parallel plate electrodes. Note that for convenience of explanation, the first electrode 21 and the second electrode 27 are omitted from FIG. 2. A high pulse voltage output from the pulsed power supply 11 is applied to the first electrode 21. A ground voltage is supplied to the second electrode 27. Note that the shape of the second electrode 27 is not limited to a cylindrical shape and may be modified as appropriate. For example, the second electrode 27 may be formed from a single flat plate member. The shapes of the first divided body 17 and the second divided body 19 are also not limited to a rectangular parallelepiped and may be modified as appropriate.

[0028] The first electrode 21 is disposed with a gap between it and the second electrode 27, so that a discharge space Fs is formed between the first electrode 21 and the second electrode 27. The discharge space Fs is a space where plasma Pr is formed when a high voltage is applied to the first electrode 21. As shown in FIG. 2 and other figures, the discharge space Fs is always connected to the space N outside the plasma reactor 9. In other words, the discharge space Fs is not blocked from the space N outside the plasma reactor 9, and is always open to the outside of the plasma reactor 9.

[0029] Because the discharge space Fs is an open space, plasma Pr can be generated in the discharge space Fs when the pressure in the discharge space Fs is atmospheric pressure. Also, plasma Pr can be generated in the discharge space Fs when the temperature in the discharge space Fs is room temperature. An example of the temperature in the discharge space Fs is 0°C or higher and 40°C or lower. An example of a preferable temperature in the discharge space Fs is 10°C or higher and 30°C or lower.

[0030] The second electrode 27 is disposed on the upper surface of the second divided body 19. The copper material Cu, which is the base material, is guided onto the upper surface of the second electrode 27. The heights of the pair of cylindrical members constituting the second electrode 27 are adjusted so that their upper surfaces are flush with each other. That is, the copper material Cu guided into the plasma generator 3 is positioned so as to be in a horizontal state by the second electrode 27. That is, the second electrode 27 also functions as a guide member that guides the copper material Cu carried into the plasma reactor 9 into a horizontal position.

[0031] The second divided body 19 is configured to move up and down in the z direction by an elevation mechanism (not shown). As the second divided body 19 moves up and down, it approaches or moves away from the first divided body 17. That is, as the second divided body 19 moves up and down, the distance between the first electrode 21 of the first divided body 17 and the second electrode 27 of the second divided body 19 changes. In other words, as the second divided body 19 moves up and down, the distance between the dielectric substrate 23 disposed on the first electrode 21 of the first divided body 17 and the copper material Cu guided to the second electrode 27 of the second divided body 19 changes. FIG. 1 shows the second divided body 19 moving to its initial position in the plasma processing apparatus 1.

[0032] As an example, the pulse power supply 11 is placed on a table 28. The pulse power supply 11 is electrically connected to the first electrode 21 and the second electrode 27 via a cable 29. The pulse power supply 11 outputs a predetermined pulse voltage. When the pulse voltage output from the pulse power supply 11 is applied to the first electrode 21, a dielectric barrier discharge occurs in the discharge space Fs between the first electrode 21 and the second electrode 27, generating a plasma Pr. The pulse power supply 11 is configured to be able to output a pulse voltage having a predetermined frequency.

[0033] The substrate supply unit 5 supplies copper material Cu, which is the substrate, to the plasma generator 3. The substrate supply unit 5 is equipped with a supply bobbin 31. A raw roll around which thin-film copper material Cu is wound is loaded on the supply bobbin 31. The supply bobbin 31 unwinds and supplies the copper material Cu from the loaded raw roll. The copper material Cu unwound from the substrate supply unit 5 is supplied to the plasma generator 3 via a guide roll 32. As shown in FIG. 2, the copper material Cu supplied to the plasma generator 3 is guided along the upper surface of the second electrode 27 in the second division 19 of the plasma reactor 9. The direction in which the copper material Cu is unwound is indicated by an arrow S1 in each drawing.

[0034] The substrate recovery unit 7 recovers the copper material Cu, which is the substrate, from the plasma generator 3. The substrate recovery unit 7 is equipped with a recovery bobbin 33. The recovery bobbin 33 winds and recovers the copper material Cu that has been plasma-treated in the plasma generator 3. That is, the copper material Cu after plasma treatment is recovered into the substrate recovery unit 7 via a guide roller 34. The supply bobbin 31 and the recovery bobbin 33 are controlled to rotate forward and backward by a motor (not shown) or the like.

[0035] In this way, by arranging the substrate supply section 5 and the substrate recovery section 7 in the plasma processing device 1 and making the discharge space Fs an open space in the plasma generating device 3, the substrate copper material Cu can be continuously supplied to the discharge space Fs.

[0036] The gas supply unit 13 contains a reactive gas Ah. One end of a gas supply pipe 35 is connected to the gas supply unit 13. The other end of the gas supply pipe 35 is disposed in the discharge space Fs of the plasma reactor 9. That is, the gas supply unit 13 supplies the reactive gas Ah to the discharge space Fs via the gas supply pipe 35. The reactive gas Ah is a gas containing hydrogen. An example of the reactive gas Ah is a gas containing argon and hydrogen.

[0037] The gas recovery unit 15 is configured to be able to contain the reactive gas Ah. One end of a gas recovery pipe 37 is connected to the gas recovery unit 15. The other end of the gas recovery unit 37 is disposed in the discharge space Fs. That is, the reactive gas Ah supplied to the discharge space Fs is recovered into the gas recovery unit 15 via the gas recovery pipe 37.

[0038] The plasma processing apparatus 1 also includes a control unit 39. The control unit 39 includes an information processing unit such as a central processing unit (CPU). The control unit 39 controls the overall operation of each component in the plasma processing apparatus 1, such as the plasma reactor 9, the pulsed power supply 11, the gas supply unit 13, and the gas recovery unit 15.

[0039] Here, the internal structure of the first divided body 17 will be described. Fig. 5 is a vertical cross-sectional view of the first divided body 17 in the plasma reactor 9. The first divided body 17 includes a frame 41, an electrode holding portion 43, a connection portion 45, and a cooling fan 47.

[0040] The frame 41 is a housing that forms the outer shell of the first split body 17. In this embodiment, the frame 41 is made of metal. The electrode holding portion 43 is arranged on the upper surface side of the first electrode 21 and holds the upper surface of the first electrode 21. The connection portions 45 are arranged on the left and right sides of the electrode holding portion 43. The connection portions 45 connect the electrode holding portion 43 and the frame 41. In other words, the electrode holding portion 43 directly holds the first electrode 21. The connection portions 45 indirectly hold the first electrode 21.

[0041] The electrode holding portion 43 and the connecting portion 45 are preferably made of a dielectric having a strength suitable for holding the first electrode 21. The electrode holding portion 43 and the connecting portion 45 are also preferably made of a material with high heat resistance. In this embodiment, the electrode holding portion 43 and the connecting portion 45 are made of aluminum oxide. Because aluminum oxide is a material with high heat resistance, even if the amount of heat generated in the first electrode 21 increases by increasing the frequency of the pulse voltage applied by the pulsed power supply 11, the plasma Pr can be generated suitably and stably.

[0042] A discharge prevention portion 46 is disposed on the connection portion 45. The discharge prevention portion 46 prevents creeping discharge from occurring between the first electrode 21 and the frame 41. In this embodiment, the discharge prevention portion 46 is an uneven portion formed on the lower surface of the connection portion 45. That is, by forming an uneven structure on the connection portion 45 disposed between the first electrode 21 and the frame 41, the creeping distance between the first electrode 21 and the frame 41 is increased. By increasing the creeping distance, it is possible to prevent creeping discharge from occurring between the first electrode 21 and the frame 41.

[0043] In the plasma processing apparatus 1, by providing the discharge prevention unit 46 that prevents creeping discharge on the first electrode 21, it is possible to avoid the occurrence of creeping discharge even when the frequency of the pulse voltage applied by the pulse power supply 11 is increased. Therefore, it is possible to perform plasma processing on a copper material Cu under conditions of a higher frequency.

[0044] As an example, the cooling fan 47 is disposed above the first electrode 21. The cooling fan 47 is disposed opposite the first electrode 21 across the electrode holder 43. The cooling fan 47 is configured to be rotatable about an axis in the z direction, and the cooling fan 47 cools the first electrode 21 by this rotation. Even if the amount of heat generated in the first electrode 21 increases by increasing the frequency of the pulse voltage applied by the pulse power supply 11, the cooling fan 47 cools the first electrode 21. In other words, it is possible to more reliably prevent the first electrode 21, the discharge space Fs, and the like from becoming too hot. Therefore, plasma processing of the copper material Cu can be performed under higher frequency conditions.

[0045] <Explanation of operation> Here, a series of operations for performing oxidation resistance treatment on copper material Cu using the plasma treatment apparatus 1 will be described.

[0046] When a command to start the oxidation-resistant treatment of the copper material Cu is issued, the operation of supplying the copper material Cu from the substrate supply unit 5 to the plasma generator 3 is started. That is, the strip-shaped copper material Cu is fed at a predetermined speed from the supply bobbin 31 of the substrate supply unit 5. The copper material Cu fed from the substrate supply unit 5 is wound around the guide roller 32, and is guided to the upper surface of the second electrode 27 arranged on the second divided body 19, and carried into the discharge space Fs.

[0047] When the copper material Cu before the oxidation resistance treatment is supplied to the plasma generator 3, the control unit 39 controls the lifting mechanism (not shown) to raise the second divided body 19. That is, under the control of the control unit 39, the second divided body 19 rises from the initial position indicated by the dotted line in FIG. 3 to the treatment position indicated by the solid line. As the second divided body 19 rises, the copper material Cu guided above the second electrode 21 approaches the dielectric substrate 23 disposed on the lower surface of the first electrode 21. An example of the distance between the dielectric substrate 23 and the copper material Cu is 0.5 mm to 2.0 mm.

[0048] After the copper material Cu is brought close to the dielectric substrate 23, the reactive gas Ah is supplied to the discharge space Fs sandwiched between the first electrode 21 and the second electrode 27. That is, the gas supply unit 13 supplies the reactive gas Ah to the discharge space Fs via the gas supply pipe 35, as shown in FIG.

[0049] After supplying the reactive gas Ah to the discharge space Fs, plasma is generated to perform surface treatment on the copper material Cu. That is, the pulse power supply 11 applies a pulse voltage having a predetermined voltage and frequency to the first electrode 21. When the pulse voltage is applied to the first electrode 21, a dielectric barrier discharge occurs in the discharge space Fs sandwiched between the first electrode 21 and the second electrode 27. That is, as shown in FIG. 4, the reactive gas Ah is excited on the lower surface of the dielectric substrate 23, and plasma Pr is generated by the dielectric barrier discharge. When the reactive gas Ah contains hydrogen, it is considered that the plasma Pr contains hydrogen plasma.

[0050] Because the second division body 19 is raised, the upper surface of the copper material Cu is close to the lower surface of the dielectric substrate 23. Therefore, plasma treatment is performed on the upper surface of the copper material Cu by the plasma Pr. As will be described later, by treating the surface of the copper material Cu with the plasma Pr generated in the discharge space Fs, the surface becomes oxidation-resistant. In other words, as a result of performing plasma treatment with the plasma Pr, oxidation-resistant treatment is performed on the copper material Cu.

[0051] After the oxidation-resistant treatment of the copper material Cu is completed, the copper material Cu is recovered. That is, the copper material Cu that has been subjected to the oxidation-resistant treatment is carried out from the discharge space Fs of the plasma generator 3. The copper material Cu that has been carried out from the discharge space Fs is wound around a guide roller 34 and guided to the base material recovery section 7. The base material recovery section 7 recovers the copper material Cu that has been subjected to the oxidation-resistant treatment by winding it onto a recovery bobbin 33. This completes the series of steps related to the oxidation-resistant treatment of the copper material Cu.

[0052] Thereafter, a pulse voltage is applied to the first electrode 21 while supplying the copper material Cu to the discharge space Fs at a predetermined rate. In the plasma generator 3, the discharge space Fs is always open to the outside. That is, when generating the plasma Pr to plasma-treat the copper material Cu, it is not necessary to seal the discharge space Fs. In other words, the copper material Cu can be continuously supplied and the plasma Pr can be continuously irradiated onto the continuously supplied copper material Cu. As a result, the copper material Cu can be plasma-treated not only by the batch method but also by a continuous treatment method, greatly improving the efficiency of the oxidation-resistant treatment of the copper material Cu.

[0053] <Explanation of oxidation resistance effect> Here, the oxidation resistance effect obtained by the plasma treatment performed using the plasma treatment apparatus 1 will be described.

[0054] <Experiment 1> 6(a), a thin-film copper material Cu was subjected to plasma treatment by the plasma treatment apparatus 1 with Kapton tape (Kapton: registered trademark) attached to a portion of the surface. That is, as shown in FIG. 6(b), Kapton tape KP was attached to a first region T1, which is the left region of the surface of the copper material Cu, and Kapton tape was not attached to a second region T2, which is the left region of the surface of the copper material Cu (the surface was exposed), and the copper material Cu was then carried into the plasma reactor 9.

[0055] Then, with the copper material Cu guided onto the upper surface of the second electrode 27, the pulse power supply 11 was operated to apply a pulse voltage to the first electrode 21, thereby generating plasma Pr in the discharge space Fs. That is, plasma treatment with plasma Pr was performed on each of the first region T1, on the surface of which Kapton tape KP was attached, and the second region T2, on which Kapton tape KP was not attached.

[0056] The conditions for the plasma treatment performed on the copper material Cu using the plasma treatment apparatus 1 are as follows. DC voltage of pulse power supply 11: 65V DC current of pulse power supply 11: 1.83A Frequency of pulse power supply 11: 80kHz Copper material Cu conveying speed: 0.5m / min Reactive gas Ah: argon / hydrogen gas (hydrogen content 8%) Pumping speed of reaction gas Ah: 6L / min Distance between the first electrode 21 and the second electrode 27: 1.0 mm Plasma treatment time: 2.5 seconds Pressure in discharge space Fs: 1 atmosphere (atmospheric pressure) Temperature of discharge space Fs: 20℃

[0057] After performing plasma treatment under the above conditions on the copper material Cu including the first region T1 and the second region T2, the Kapton tape KP was peeled off from the first region T1 of the copper material Cu, and the entire copper material Cu was heated for 1 hour at 150° C. The surface colors of the first region T1 and the second region T2 of the copper material Cu were observed before and after the heating.

[0058] Fig. 6(c) is a diagram showing the color of the first region T1 and the second region T2 after plasma treatment and before heating. Fig. 6(d) is a diagram showing the color of the first region T1 and the second region T2 after heating at 150°C for 1 hour. Fig. 6(e) is a graph showing the film thickness of the copper oxide (oxide film thickness) formed in the first region T1 and the second region T2 after heating at 150°C for 1 hour.

[0059] When performing plasma treatment on copper material Cu, a plasma-resistant Kapton tape KP is attached to the surface of the first region T1. That is, the plasma Pr irradiated onto the first region T1 is blocked by the Kapton tape KP. That is, the first region T1 corresponds to a non-treatment region where plasma treatment is not performed. On the other hand, the Kapton tape KP is not attached to the surface of the first region T1, and the plasma Pr is irradiated in an exposed state. That is, the second region T2 corresponds to a treatment region where plasma treatment is performed.

[0060] As shown in Fig. 6(c), after the irradiation with plasma Pr but before the heat treatment, the color of the copper material Cu in the first region T1 is the same as the color of the copper material Cu in the second region T2. ​​On the other hand, as shown in Fig. 6(d), after the irradiation with plasma Pr and the heat treatment, the color of the first region T1, which has not been subjected to plasma treatment, is darker and more reddish-brown than the color of the second region T2, which has been subjected to plasma treatment (see symbol B).

[0061] In other words, in the second region T2, the oxidation of copper progressed due to heating, and the color of copper oxide became clearly apparent. On the other hand, in the first region T1, the oxidation of copper did not progress even after heating, and the color of copper oxide did not appear. In fact, in the first region T1, where plasma treatment was not performed, the thickness of the copper oxide formed by the heat treatment was 15.7 nm, while in the second region T2, where plasma treatment was performed, the thickness of the copper oxide formed by the heat treatment was 9.6 nm. The thickness of the copper oxide film in the copper material Cu after the heat treatment was measured using the continuous electrochemical reduction method (SERA method).

[0062] The results of Experiment 1 revealed that the second region T2, which was subjected to plasma treatment, had higher oxidation resistance than the first region T1, which was not subjected to plasma treatment. That is, it was found that plasma treatment using the plasma treatment apparatus 1 according to this embodiment can impart high oxidation resistance to the copper material Cu. In other words, it was found that irradiating the copper material Cu with plasma Pr using the plasma treatment apparatus 1 enables oxidation resistance treatment of the copper material Cu.

[0063] <Experiment 2> To evaluate the oxidation resistance of copper material Cu treated with plasma Pr, samples 1 to 7 of copper material Cu were prepared using different plasma Pr treatment conditions. The plasma-treated samples 1 to 7 were then heated at 200°C for 30 minutes, and the color of each sample was observed to evaluate whether or not there was an improvement in oxidation resistance. The results are shown in Table 1 below.

[0064] [Table 1]

[0065] In Table 1, the power density (unit: W / cm 2 ) is the ratio of input power (unit: W) to discharge area (unit: cm 2 ) The input power corresponds to the value of the power input to the pulsed power supply 11. The frequency value corresponds to the frequency of the pulsed voltage applied by the pulsed power supply 11. As the frequency of the pulsed voltage increases, the value of the input power increases.

[0066] The discharge area is the area of ​​the copper material Cu to be processed by the plasma Pr, and corresponds to 2.1 cm wide x 5.8 cm long. In samples 1 to 5, the reactive gas Ah was argon / hydrogen gas (hydrogen content 8%, argon content 92%), as in experiment 1. In sample 6, the reactive gas Ah was argon gas, which does not contain hydrogen. In sample 7, the reactive gas Ah was helium / hydrogen gas (hydrogen content 8%, helium content 92%).

[0067] In Table 1, when an "x" is marked in the column for evaluation of improved oxidation resistance, it indicates that the color of the copper material Cu sample after heating was the same color as the first region T1 in Experiment 1. In other words, the surface of the sample was a dark color with a strong reddish-brown color, meaning that no improvement in oxidation resistance was observed in the copper material Cu sample.

[0068] In Table 1, when an "○" is marked in the column for evaluation of improved oxidation resistance, it indicates that the color of the copper material Cu sample after heating is the same color as that of the second region T2 in Experiment 1. In other words, no copper oxide color is observed on the surface of the sample, meaning that the oxidation resistance of the copper material Cu sample has been greatly improved. In other words, when an "○" is marked in the column for evaluation of improved oxidation resistance, it indicates that the plasma treatment has achieved an oxidation resistance improvement effect similar to that of the second region T2 in Experiment 1.

[0069] In Table 1, when a "△" symbol is added to the column for evaluation of improved oxidation resistance, it indicates that the color of the copper material Cu sample after heating was a weaker reddish-brown color than that of the first region T1 in Experiment 1. In other words, it means that the plasma treatment was confirmed to have an improved oxidation resistance effect on the copper material Cu sample, although the effect was weaker than that of the second region T2.

[0070] For samples 1 to 5, plasma treatment was performed on copper material Cu by varying the conditions of the input power input to the pulse power supply 11. In experiment 2, the discharge area, i.e., the area of ​​the copper material Cu to be subjected to plasma treatment, was constant. Therefore, the power density changed with the change in input power. Furthermore, the frequency of the pulse voltage applied to the first electrode 21 also changed with the input power.

[0071] While no improvement in oxidation resistance was confirmed for Samples 1 and 2, which were subjected to low input power conditions, improvement in oxidation resistance was confirmed for Sample 3, which was subjected to a higher input power than Sample 2. Furthermore, significant improvements in oxidation resistance were confirmed for Samples 4 and 5, which were subjected to even higher input power than Sample 3. This indicates that increasing the power density increases the effect of plasma treatment on improving oxidation resistance. In other words, increasing the frequency of the pulse voltage increases the effect of plasma treatment on improving oxidation resistance.

[0072] Specifically, the power density is 3.1 W / cm 2 When the power density is 5.9 W / cm or more, the plasma treatment is effective in improving oxidation resistance. 2 It was found that a high oxidation resistance improvement effect can be obtained by plasma treatment when the frequency of the pulse voltage is 20 kHz or more, and that a high oxidation resistance improvement effect can be obtained by plasma treatment when the frequency of the pulse voltage is 40 kHz or more as a preferable condition.

[0073] In terms of the performance of the device, there is an upper limit to the amount of power that can be input to the pulse power supply 11. For example, the practical upper limit of the power that can be input to the pulse power supply 11 is 400 W / cm. 2 Therefore, the power density is 3.1W / cm 2 or more and 400W / cm 2 The plasma treatment is effective in improving oxidation resistance when the power density is 5.9 W / cm or less. 2 or more and 400W / cm 2 When the temperature is below this, the plasma treatment can provide a high effect of improving oxidation resistance.

[0074] Furthermore, 300 kHz is an example of a substantial upper limit of the frequency of the pulse voltage applied by the pulse power supply 11. Therefore, when the frequency is 20 kHz or more and 300 kHz, the effect of improving oxidation resistance by the plasma treatment can be obtained, and preferably, when the frequency is 40 kHz or more and 300 kHz or less, the effect of improving oxidation resistance by the plasma treatment can be obtained.

[0075] For Samples 5 to 7, plasma treatment was performed on copper material Cu using different types of gases as the reactive gas Ah. When argon / hydrogen gas was used as the reactive gas Ah, as in Experiment 1, plasma treatment demonstrated a significant improvement in oxidation resistance (Sample 4). On the other hand, when argon gas was used as the reactive gas Ah, no improvement in oxidation resistance was observed due to plasma treatment (Sample 6). Furthermore, when helium / hydrogen gas was used as the reactive gas Ah, an improvement in oxidation resistance was observed due to plasma treatment (Sample 7). From the results of Samples 5 to 7, it is believed that when hydrogen gas is included in the reactive gas Ah supplied to the discharge space Fs, plasma treatment can be effective in improving oxidation resistance.

[0076] <Effects of the configuration of the embodiment> As described above, the inventors' intensive studies have revealed that the oxidation resistance of copper material Cu can be significantly improved by irradiating copper material Cu with plasma Pr using plasma processing apparatus 1 according to the embodiment. In other words, it has been revealed that oxidation resistance treatment of copper material Cu is possible by irradiating copper material Cu with plasma Pr using plasma processing apparatus 1.

[0077] In conventional oxidation-resistant treatments, a protective film containing an oxidation-resistant compound is formed on the surface of a copper material by applying a rust inhibitor to the copper material or plating the surface of the copper material. While this prevents the copper material from oxidizing while stored in a warehouse, the protective film, which contains components different from copper, can interfere with various post-treatment processes. Therefore, when using copper material that has undergone conventional oxidation-resistant treatments, a process for removing the protective film must be carried out before the post-treatment process.

[0078] On the other hand, in the oxidation-resistant treatment according to this embodiment, the oxidation resistance of the copper material Cu can be improved by irradiating the copper material Cu with plasma Pr. Furthermore, the surface of the copper material Cu irradiated with plasma Pr is free of components that would interfere with post-treatment processes. Therefore, oxidation of the copper material can be prevented while the copper material is stored in a warehouse or the like, and the copper material Cu that has undergone the oxidation-resistant treatment can be directly subjected to post-treatment processes. Therefore, the efficiency of processes such as manufacturing electrical components using copper material can be greatly improved.

[0079] The plasma processing apparatus 1 also includes a first electrode 21 having a dielectric substrate 23 and a second electrode 27 disposed opposite the dielectric substrate 23. A voltage is applied between the first electrode 21 and the second electrode 27 to generate plasma Pr in a discharge space Fs, which is the space between the first electrode 21 and the second electrode 27. In other words, the plasma processing apparatus 1 performs plasma processing, i.e., oxidation-resistant processing, on copper material Cu using plasma Pr generated by a dielectric barrier discharge method. By using the dielectric barrier discharge method, highly uniform plasma Pr can be generated over a wider range. This significantly improves the processing efficiency of oxidation-resistant processing using the plasma processing apparatus 1. Furthermore, it is possible to more reliably prevent unevenness from occurring in the oxidation-resistant processing of copper material Cu.

[0080] The plasma processing apparatus 1 includes a discharge prevention unit 46 that prevents discharge at the first electrode 21 and a cooling fan 47 that cools the first electrode 21. Generally, when a high-frequency pulse voltage is applied to an electrode for generating plasma, creeping discharge tends to occur at the electrode, and heat generated at the electrode increases. Because of the occurrence of such discharge and heat, it is difficult to increase the frequency of the pulse voltage in conventional plasma processing apparatuses. In other words, it is difficult to increase the power density in conventional plasma processing apparatuses.

[0081] On the other hand, in the plasma processing apparatus 1 according to the embodiment, a discharge prevention unit 46 is provided on the connection unit 45 that holds the first electrode 21. Providing the discharge prevention unit 46 on the connection unit 45 can prevent the occurrence of creeping discharge at the first electrode 21. Therefore, the plasma Pr can be generated under conditions in which the frequency of the pulse voltage applied to the first electrode 21 is increased. In other words, the plasma Pr can be generated under conditions in which the power density to the first electrode 21 is increased. Therefore, plasma processing of the copper material Cu becomes possible under conditions that exhibit the effect of improving the oxidation resistance of the copper material Cu.

[0082] The plasma processing apparatus 1 also includes a cooling fan 47 for cooling the first electrode 21 inside the first division 17 of the plasma reactor 9. By providing the cooling fan 47, it is possible to prevent the first electrode 21 from becoming too hot. Therefore, the plasma Pr can be generated under conditions in which the frequency of the pulse voltage applied to the first electrode 21 is increased. Therefore, it is possible to perform plasma processing on the copper material Cu under conditions that improve the oxidation resistance of the copper material Cu.

[0083] Furthermore, in the plasma processing apparatus 1, the discharge space Fs where the plasma Pr is generated is an open space. That is, the discharge space Fs arranged inside the plasma reactor 9 is always connected to the space N outside the plasma reactor 9. When the discharge space Fs is arranged in a closed space, such as a processing chamber, steps are required to temporarily open the discharge space Fs and load the copper material Cu to be plasma-processed into the discharge space Fs, to transition the discharge space Fs from an open state to a closed state, and to temporarily open the discharge space Fs and load the copper material Cu after plasma processing out of the discharge space Fs. In other words, when the discharge space Fs is arranged in a closed space, such as a processing chamber, the method for transporting the copper material Cu into the discharge space Fs is limited to a batch method.

[0084] On the other hand, because the discharge space Fs is an open space, the copper material Cu can be plasma-treated using a method of continuously transporting the copper material Cu to the discharge space Fs, i.e., a continuous treatment method (streaming method). In this case, the treatment efficiency of the oxidation-resistant treatment of the copper material Cu can be greatly improved by using the continuous treatment method, compared to the batch method, which requires a step of temporarily stopping the transport of the copper material Cu.

[0085] Furthermore, by making the discharge space Fs an open space, the plasma processing apparatus 1 generates the plasma Pr under conditions where the discharge space Fs has the same pressure and temperature as the air outside the plasma processing apparatus 1. In other words, the plasma processing apparatus 1 can perform oxidation resistance treatment on the copper material Cu using the plasma Pr generated under atmospheric pressure and room temperature conditions. Therefore, there is no need to provide the plasma processing apparatus 1 with a configuration for adjusting the pressure or temperature of the discharge space Fs where the plasma Pr is generated. This allows the plasma processing apparatus 1 to be made smaller and the costs required for the plasma processing apparatus 1 to be reduced.

[0086] Furthermore, by generating plasma Pr under relatively low temperature conditions, it is possible to generate low-temperature plasma in which only electrons have high energy. Therefore, even under relatively low electron density or frequency conditions, it is possible to generate plasma Pr with higher energy and plasma treat copper material Cu. It is believed that using plasma Pr with higher energy can further improve the effectiveness of oxidation-resistant treatment of copper material Cu.

[0087] <Other Examples> It should be noted that the embodiments disclosed herein are illustrative in all respects and are not limiting. The scope of the present invention includes the claims and all modifications within the meaning and scope of the claims. For example, the present invention can be modified as follows:

[0088] (1) In the above-described embodiment, a configuration in which a thin-film copper material Cu is used as the target of plasma processing is exemplified, but this is not limiting. In addition to a thin-film copper foil, the copper material Cu may also be a plate-shaped copper plate or a wire-shaped copper wire. In this case, the configurations of the substrate supply unit 5 and the substrate recovery unit 7 may be appropriately changed depending on the shape of the copper material Cu.

[0089] (2) In the above-described embodiments, the discharge space Fs is an open space, but this is not limiting. Specifically, the plasma reactor 9 may include a sealable processing chamber, with the first electrode 21, the dielectric substrate 23, and the second electrode 27 provided inside the processing chamber. In this case, the discharge space Fs is formed inside the sealable processing chamber. Furthermore, by forming the discharge space Fs inside the processing chamber, it becomes possible to generate plasma Pr under conditions where the interior of the processing chamber is adjusted to a predetermined pressure or temperature. As an example, copper material Cu may be irradiated with plasma Pr generated under vacuum conditions to perform oxidation-resistant treatment on the copper material Cu.

[0090] (3) In the above-described embodiment, the configuration for cooling the first electrode 21 is not limited to the cooling fan 47. As an example, a cooling member such as a Peltier element may be brought into contact with the first electrode 21 or the electrode holder 43, and the first electrode 21 may be cooled by the cooling member. Furthermore, the configuration of the discharge prevention unit 46 is not limited to the uneven structure formed on the connection unit 45, and any suitable member and configuration may be used as long as it can prevent discharge in the first electrode 21. Furthermore, the location where the discharge prevention unit 46 is disposed is not limited to the connection unit 45, and the discharge prevention unit 46 may be disposed in any suitable location.

[0091] (4) In each of the above-described embodiments, the entire discharge space Fs inside the plasma reactor 9 is connected to the external space N of the plasma reactor 9, but this is not limiting. That is, as shown in Figs. 7 and 8, a member may be provided that shields at least a part of the discharge space Fs from the external space N.

[0092] 7 is a front view showing the initial state of a plasma reactor 9A according to a modified example. The plasma reactor 9A includes a first shielding section 51 and a second shielding section 53. The first shielding section 51 is disposed on the outer periphery of the first divided body 17 so as to surround the first divided body 17. The second shielding section 53 is disposed on the outer periphery of the second divided body 19 so as to surround the second divided body 19.

[0093] The lower end 51a of the first shielding portion 51 is configured to be located at a position lower than the lower end of the first divided body 17. The height of the lower end 51a of the first shielding portion 51 is designed in advance so that the lower end 51a does not press against the copper material Cu when the second divided body 19 rises from the initial position to the processing position. In other words, the height of the lower end 51a of the first shielding portion 51 is determined in advance so that the first shielding portion 51 does not interfere with the transport of the copper material Cu when the second divided body 19 rises from the initial position to the processing position.

[0094] The upper end 53a of the second shielding part 53 is configured to be higher than the upper end of the second divided body 19. That is, the first shielding part 51 shields at least a part of the discharge space Fs from the external space N of the plasma reactor 9. The second shielding part 53 also shields at least a part of the discharge space Fs from the external space N of the plasma reactor 9.

[0095] The shape of the upper end 53a of the second shielding part 53 is preferably a shape corresponding to the trajectory of the copper material Cu being transported. In this case, as shown in Fig. 7, the copper material Cu being transported into the plasma reactor 9 and the copper material Cu being transported out of the plasma reactor 9 are each in contact with the upper end 53a of the second shielding part 53. In other words, the upper end 53a of the second shielding part 53 supports the lower surface of the copper material Cu. As a result, the posture of the copper material Cu being transported can be more stabilized.

[0096] In the plasma reactor 9A according to the modified example, the gas recovery pipe 37 is arranged to penetrate the first shielding portion 51. The gas recovery pipe 37 is preferably arranged to penetrate the first shielding portion 51 at multiple locations along the outer periphery of the first shielding portion 51. As an example, as shown in FIG. 7, the gas recovery pipes 37 are arranged on the left and right sides of the plasma reactor 9A. In this case, the reactive gas Ah supplied to the discharge space Fs is discharged from the left and right sides of the plasma reactor 9A to the gas recovery pipes 37 and recovered in the gas recovery portion 15 through the gas recovery pipes 37. By configuring the reactive gas Ah to be recovered from both sides of the discharge space Fs in this way, the reactive gas Ah can be recovered efficiently. In particular, hydrogen gas contained in the reactive gas Ah can be recovered more reliably.

[0097] 8 shows a state in which the second divided body 19 has moved from the initial position to the processing position in a plasma reactor 9A according to a modified example. As the second divided body 19 moves from the initial position to the processing position, the lower end 51a of the first shielding part 51 approaches the upper surface of the copper material Cu. As a result, the area of ​​the discharge space Fs that is connected to the external space N is reduced, and the airtightness of the discharge space Fs is improved. By improving the airtightness of the discharge space Fs, the concentration of the reactive gas Ah in the discharge space Fs can be further increased.

[0098] Even when the second divided body 19 is raised to the processing position, the lower end 51a is at a height that does not contact the copper material Cu. This prevents the copper material Cu from being pinched from above and below by the lower end 51a of the first shielding part 51 and the upper end 53a of the second shielding part 53, thereby preventing the copper material Cu from being impeded in transport. When the second divided body 19 is raised from the initial position to the processing position, the discharge space Fs is connected to the external space N of the plasma reactor 9 to an extent that allows the copper material Cu to be continuously transported. That is, in the embodiment, the entire discharge space Fs is always connected to the external space N, while in the modified example, only a portion of the discharge space Fs is always connected to the external space N.

[0099] In a plasma processing apparatus 1 equipped with a plasma reactor 9A according to the modified example, as shown in Fig. 8, after the second divided body 19 is raised to the processing position, a reactive gas Ah is supplied from the gas supply unit 13 to the discharge space Fs, while a pulse voltage is applied from the pulse power supply 11 to the first electrode 21. By applying the pulse voltage, a plasma Pr is generated in the discharge space Fs, the airtightness of which has been improved, and plasma processing is performed on the surface of a copper material Cu carried into the discharge space Fs. As a result of this plasma processing, the oxidation resistance of the copper material Cu is improved.

[0100] In this modification, while maintaining a state in which the copper material Cu can be continuously transported, the airtightness of the discharge space Fs is improved by the first shielding part 51 and the second shielding part 53. Therefore, it is possible to perform oxidation resistance treatment of the copper material Cu by a continuous treatment method while increasing the concentration of the reactive gas Ah, thereby improving the treatment effect and treatment efficiency of the oxidation resistance treatment.

[0101] (5) In the above-described embodiment and modified examples, the configurations of the gas supply pipe 35 and the gas recovery pipe 37 may be changed as appropriate. That is, as an example, the locations and numbers of the gas supply pipe 35 and the gas recovery pipe 37 are not limited to the embodiments shown in Figures 1 and 7, and can be changed as appropriate. [Explanation of symbols]

[0102] 1. Plasma processing equipment 3...Plasma generator 5...Base material supply section 7...Substrate recovery section 9, 9A...Plasma reactor 11...Pulse power supply 13...Gas supply section 15...Gas recovery section 17...First division 19...Second division 21...1st electrode 23...Dielectric substrate 27...Second electrode 29...Cable 31...Supply bobbin 33...Recovery bobbin 35...Gas supply pipe 37...Gas recovery pipe 39...Control unit 41...frame section 43...Power supply holding part 45...Connection 46...Discharge prevention part 47...Cooling fan 51...First shielding part 53...Second shielding part

Claims

1. A method for oxidation resistance treatment of a copper material using plasma, comprising: A reaction gas containing hydrogen was supplied with a power density of 3.1 W / cm ２ The oxidation resistance treatment method for a copper material comprises a plasma treatment step of irradiating the copper material with plasma generated under the above conditions.

2. A method for oxidation resistance treatment of a copper material using plasma, comprising: A method for oxidation-resistant treatment of a copper material, comprising a plasma treatment process in which a reactive gas containing hydrogen is supplied while a pulse voltage having a frequency of 20 kHz or more is applied to generate plasma, which is then irradiated onto the copper material.

3. The oxidation resistance treatment method for a copper material according to claim 1 or 2, The plasma treatment process includes: The copper material is irradiated with the plasma generated by a dielectric barrier discharge method.

1. A method for oxidation-resistant treatment of a copper material, comprising:

4. The oxidation resistance treatment method for a copper material according to claim 1 or 2, The plasma treatment process includes: The copper material being transported in a continuous processing manner is irradiated with the plasma.

1. A method for oxidation-resistant treatment of a copper material, comprising:

5. a plate-shaped dielectric substrate; a first electrode disposed on one surface of the dielectric substrate; a second electrode disposed opposite the first electrode via the dielectric substrate; a gas supply unit that supplies a reactive gas containing hydrogen to a discharge space that is a space between the first electrode and the second electrode; a pulse power supply that applies a pulse voltage to at least one of the first electrode and the second electrode; Equipped with The discharge space is configured so that at least a portion thereof is always connected to the outside, The pulse power source has a power density of 3.1 W / cm ２ The plasma processing apparatus is configured to apply a pulse voltage of at least 1000 V.

6. a plate-shaped dielectric substrate; a first electrode disposed on one surface of the dielectric substrate; a second electrode disposed opposite the first electrode via the dielectric substrate; a gas supply unit that supplies a reactive gas containing hydrogen to a discharge space that is a space between the first electrode and the second electrode; a pulse power supply that applies a pulse voltage to at least one of the first electrode and the second electrode; Equipped with The discharge space is configured so that at least a portion thereof is always connected to the outside, The plasma processing apparatus is configured such that the pulse power supply applies a pulse voltage having a frequency of 20 kHz or more.

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