Plasma processing device

Abstract

Provided is a plasma processing device capable of applying high-quality plasma processing to a surface to be processed of a workpiece while suppressing mixing of process gas and outside air. A plasma processing device 10 comprises: a device body 20; a discharge unit 50 for generating plasma; a plurality of gas injection holes 64 which are disposed at a lower portion of the device body 20 and around the discharge unit 50 and inject process gas; a cover member 80 which surrounds the entire circumference of the device body 20 in a circumferential direction, has a frame shape protruding in a direction closer to a workpiece 1 than the lower end 21 of the device body 20, and covers the outer circumference of all of the plurality of gas injection holes 64; and an adjustment mechanism that allows adjustment of the amount of protrusion of the lower end 21 of the device body 20 relative to the lower end 81 of the cover member 80.

Description

Plasma processing apparatus

[0001] The present invention relates to a plasma processing apparatus that generates plasma by introducing a process gas and applying a voltage, and performs plasma processing on the processing surface of a workpiece.

[0002] Conventionally, there has been a plasma processing apparatus that irradiates the surface of a workpiece with plasma for surface treatment in order to sterilize the surface of the workpiece, improve its wettability, improve the adhesiveness of fluororesins, etc.

[0003] For example, Patent Document 1 below discloses an atmospheric pressure plasma processing apparatus including a pair of electrode units that form a plasma processing space, a workpiece feeding mechanism that feeds a workpiece toward the plasma processing space, and a processing gas blowing means that blows a processing gas toward the processing space. The workpiece feeding mechanism is provided with a cutting member that cuts off the atmosphere on the side of the other electrode unit from the blowing flow of the processing gas with respect to the plane in which the workpiece moves.

[0004] Also, closing members that close the two ends orthogonal to the end continuous with the processing space in the space between the processing gas blowing means and the cutting member are provided so as to be sandwiched between the processing gas blowing means and the cutting member.

[0005] JP-A-2004-311256

[0006] In the case of the atmospheric pressure plasma processing apparatus described in Patent Document 1 above, although the left and right ends of the processing space are closed by the closing members, these closing members do not have a structure that covers all the blowing holes, and there was a possibility that the gas in the processing space and the outside air might be mixed.

[0007] Further, when the surface state of the workpiece, for example, when the undulations due to irregularities or the like on the workpiece surface are large, it is necessary to adjust the gap between the workpiece and the lower end of the closing member. In the case of the atmospheric pressure plasma processing apparatus described in Patent Document 1 above, there is no such adjustment structure, and there was a possibility that it might interfere with the quality of the surface of the workpiece that has been subjected to plasma processing.

[0008] Therefore, an object of the present invention is to provide a plasma processing apparatus that can suppress mixing of process gas and outside air, and can perform high-quality plasma processing on the surface of an object to be processed.

[0009] To achieve the above objective, the plasma processing apparatus according to the present invention generates plasma by introducing a process gas and applying a voltage to process the surface of an object to be processed, and is characterized by comprising: an apparatus body having a gas inlet hole for introducing the process gas and a gas flow passage for circulating the process gas; a discharge unit provided at the lower part of the apparatus body for generating the plasma; a plurality of gas ejection holes located at the lower part of the apparatus body and arranged around the discharge unit, communicating with the gas flow passage and ejecting the process gas; a cover member having a frame shape that surrounds the entire circumference of the apparatus body in the circumferential direction and protrudes in a direction closer to the object to be processed than the lower end of the apparatus body, and covering the outer circumference of all of the plurality of gas ejection holes; and an adjustment mechanism that allows adjustment of the amount of protrusion of the lower end of the apparatus body relative to the lower end of the cover member.

[0010] According to the present invention, since the frame-shaped cover member covers the entire outer circumference of the multiple gas ejection holes, a plasma processing space is formed inside the portion of the cover member that protrudes from the lower end of the main body of the apparatus, where process gas is filled to enable plasma processing. Furthermore, the cover member effectively suppresses the mixing of the process gas filled in the plasma processing space with the outside air present outside the cover member.

[0011] Furthermore, since the adjustment mechanism allows for adjustment of the amount of protrusion of the lower end of the device body relative to the lower end of the cover member, the volume of the plasma treatment space can be changed according to the condition of the surface of the workpiece, and the distance of the discharge part from the surface of the workpiece can be adjusted, thereby enabling high-quality plasma treatment of the surface of the workpiece.

[0012] In the plasma processing apparatus according to the present invention, the discharge section extends in a predetermined direction, and a plurality of gas ejection holes are arranged at predetermined intervals along the extension direction of the discharge section to constitute a gas ejection section, and the gas ejection section is arranged on the outside of both sides in the width direction perpendicular to the extension direction of the discharge section, and the opening direction of each gas ejection hole constituting the gas ejection section may be inclined to face inward in the width direction perpendicular to the extension direction of the discharge section.

[0013] According to the above embodiment, the gas ejection sections are arranged on the outside of both sides in the width direction of the discharge section, and the opening direction of each gas ejection hole is inclined to face inward in the width direction perpendicular to the extension direction of the discharge section, so that the process gas is concentrated and ejected toward the center of the discharge section in the width direction. For this reason, for example, by positioning a desired location on the workpiece in the width direction of the main body of the discharge section, plasma treatment can be effectively applied to the desired location on the surface of the workpiece.

[0014] Furthermore, the distance between the lower end of the cover member and the surface of the workpiece can be made longer than when the opening of the gas ejection hole is straight and not inclined, allowing for more flexible adaptation to irregularities on the surface of the workpiece.

[0015] Furthermore, the process gas ejected from the pair of gas ejection ports remains within the protruding portion of the cover member and in the center of the width direction of the discharge section, making it difficult for it to escape from the lower end opening of the cover member. This makes it easier to keep the lower end of the cover member away from the surface of the workpiece, allowing for flexible adaptation even when the workpiece surface has significant irregularities, and maintaining the quality of plasma treatment on the workpiece surface.

[0016] In the plasma processing apparatus according to the present invention, the apparatus body comprises a main body portion extending in a predetermined direction and forming a gas inlet hole and a part of the gas flow passage, and a pair of side portions separate from the main body portion and fixed to both sides in the width direction perpendicular to the extension direction of the main body portion, forming the remaining part of the gas flow passage and provided with the gas ejection portion, and an inclined surface is formed on the lower end of each side portion facing the main body portion, on the side of the lower end of the side portion facing the main body portion that gradually becomes thinner toward the main body portion, and the gas ejection portion may be formed on the inclined surface.

[0017] According to the above embodiment, the device body has a structure having a main body and a pair of side parts separate from the main body, so that a gas flow passage can be reliably formed inside the device body. Furthermore, since gas ejection parts are formed on the inclined surfaces formed on the lower ends of each side part, which are separate from the main body and face the main body, it is easy to form gas ejection holes even if the inner diameter of the gas ejection holes is minute.

[0018] According to the present invention, the cover member forms a plasma processing space, effectively suppressing the mixing of process gas and outside air. Furthermore, the adjustment mechanism allows for changing the volume of the plasma processing space according to the condition of the surface of the workpiece, thereby appropriately adjusting the distance of the discharge section to the surface of the workpiece. This enables high-quality plasma processing to be applied to the surface of the workpiece.

[0019] Figure 2 shows one embodiment of the plasma processing apparatus according to the present invention, and is a perspective view of the apparatus body and cover member. A perspective view of the plasma processing apparatus. A cross-sectional view of the apparatus body constituting the plasma processing apparatus, taken along the line A-A in Figure 2. A bottom view of the apparatus body constituting the plasma processing apparatus. A cross-sectional view taken along the line B-B in Figure 2. A cross-sectional view taken along the line C-C in Figure 2. A cross-sectional view showing an example of use of the plasma processing apparatus. A photograph showing the test results of a test to determine whether plasma processing is sufficiently performed when a cover member is present or absent, and when the amount of protrusion of the lower end of the apparatus body relative to the lower end of the cover member is adjusted by an adjustment mechanism. A graph of the test results of spectral analysis by XPS, in the case of a comparative example without a cover member. A graph of the test results of spectral analysis by XPS, where (a) is a graph of an example in which a cover member is present and the plasma irradiation distance from the discharge part is 1 mm, and (b) is a graph of an example in which a cover member is present and the plasma irradiation distance from the discharge part is 3 mm.

[0020] (An Embodiment of a Plasma Processing Apparatus) Hereinafter, an embodiment of the plasma processing apparatus according to the present invention will be described with reference to the drawings.

[0021] As shown in Figure 7, the plasma processing apparatus 10 (hereinafter also simply referred to as "processing apparatus 10") in this embodiment generates plasma by introducing a process gas G and applying a voltage, and performs surface treatment on the workpiece 1. The process gas G may be, for example, Ar or H ２ A substance with as its main component can be used.

[0022] As shown in Figures 1 to 3, 5, and 6, the processing apparatus 10 comprises a main body 20, a discharge unit 50 for generating plasma, a plurality of gas ejection holes 64 for ejecting process gas G, a cover member 80 that protrudes from the lower end 21 of the main body 20 and covers the entire outer circumference of the plurality of gas ejection holes 64, and an adjustment mechanism that allows adjustment of the amount T (see Figures 5 to 7) of the lower end 21 of the main body 20 protruding relative to the lower end 81 of the cover member 80.

[0023] Furthermore, the adjustment mechanism allows for adjustment of the distance of the lower end 58 of the discharge section 50 to the surface 3 of the workpiece 1. In this embodiment, the surface 3 of the workpiece 1 is the surface of the workpiece 1.

[0024] First, the main body of the apparatus 20 will be described in detail. The main body of the apparatus 20 has a gas inlet hole 31 for introducing process gas G and a gas flow passage for circulating the process gas G, and is mainly composed of a main body portion 30 extending in a predetermined direction and a pair of side portions 60, 61 fixed in the width direction perpendicular to the extension direction of the main body portion 30. Furthermore, a contact member 38 that contacts the discharge portion 50 is arranged inside the main body of the apparatus 20 via a support member 37 (see Figures 3, 5, and 6).

[0025] The main body portion 30 is block-shaped and extends for a predetermined length in a predetermined extension direction L, and a part of the gas inlet hole 31 and gas flow passage are formed therein. When the device body 20 is viewed from a plan view, the direction perpendicular to the extension direction L is defined as the "width direction W," and the direction perpendicular to both the extension direction L and the width direction W is defined as the "height direction H" (this applies not only to the main body portion 30 but also to other components such as the discharge section 50 and side sections 60, 61).

[0026] As shown in Figures 3 and 5, a gas inlet 31 is formed in the center of the main body 30 in the extension direction L and in the center of the width direction W, for introducing process gas G into the apparatus body 20. Also, as shown in Figures 3 and 5, a first gas flow passage 33 is formed in the main body 30 in the center of its extension direction L and slightly above the height direction H, connecting one end of the main body 30 in the width direction W (the front end) and the other end in the width direction W (the rear end), and also communicating with the gas inlet 31.

[0027] Furthermore, as shown in Figure 3, plug mounting holes 34a and 35a are formed in the main body portion 30, near both ends in the extension direction L, on either side of the gas inlet hole 31, and in the center in the width direction W.

[0028] A connector 32, to which a tube (not shown) is connected for supplying process gas G from a process gas supply source, is connected to the gas inlet hole 31 described above. In addition, plugs 34 and 35, which are connected to a power supply (not shown), are respectively installed in the plug mounting holes 34a and 35a. That is, the connector 32 is located in the center of the extension direction L of the device body 20, and the pair of plugs 34 and 35 are located near both ends of the extension direction L, flanking the connector 32.

[0029] Each plug 34 and 35 has cables 34b and 35b that are connected to the discharge section 50. Plug 34 is on the ground side (GND), and plug 35 applies voltage to the discharge section 50 (VDD). In addition, insertion holes 34c and 35c are formed in the main body 30 at positions adjacent to each mounting hole 34a and 35a, respectively, and the cables 34b and 35b of plugs 34 and 35 corresponding to each insertion hole 34c and 35b are inserted through them (see Figure 3).

[0030] Furthermore, a recessed groove-shaped housing section 36 is formed at the lower part of the main body 30 in the height direction H, with an opening at the bottom and extending along the extension direction L. A support member 37, which is roughly the shape of a long frame and extends along the extension direction L, is housed in this housing section 36 (see Figure 3). A pair of elongated gaps 37a, 37a are formed at both ends of the support member 37 in the extension direction L, and the lower ends of the plugs 34, 35 are positioned in each gap 37a (see Figure 3).

[0031] Furthermore, as shown in Figure 1, circular fixing holes 41 are formed on the outer surfaces of both ends of the main body portion 30 in the extension direction L, and in the central part in the width direction W.

[0032] Next, the discharge section 50 will be described in detail. As shown in Figure 4, the discharge section 50 is a roughly rectangular plate-like body that extends elongated along the extension direction L, and multiple screw holes 53 are formed at both ends 51 and 52 in the extension direction L. The discharge section 50 is fixed to the support member 37 in contact with the contact member 38 by screws (not shown) inserted through the multiple screw holes 53 (see Figure 3).

[0033] Furthermore, as shown in Figure 4, an electrode surface 55 with a substantially rectangular shape is formed in the center of the width direction W of the discharge section 50, extending from one end 51 to the other end 52 in the extension direction L, and a discharge surface 56 is provided around the electrode surface 55.

[0034] Furthermore, a grounding portion 57 is formed on one end 51 of the discharge portion 50 (see Figure 4), and one end of the cable 34b of the plug 34 abuts against this grounding portion 57 (see Figure 3). Also, one end of the cable 35b of the plug 35 abuts against a location near the other end 52 of the discharge portion 50 (see Figure 3).

[0035] Then, with the process gas G ejected from the multiple gas ejection holes 64 filling the plasma processing space S (see Figures 5-7), when a voltage is applied to the electrode surface 55 of the discharge section 50 via the plugs 34 and 35, surface discharge occurs along the extension direction L of the discharge surface 56.

[0036] Next, the side portions 60 and 61 will be described in detail. These side portions 60 and 61 are separate from the main body portion 30 and are fixed to both sides of the main body portion 30 in the width direction W. It can also be said that the side portions 60 are positioned and fixed to the front side of the main body portion 30, and the side portions 61 are positioned and fixed to the rear side of the main body portion 30.

[0037] Each side portion 60, 61 is roughly plate-shaped, conforming to the length along the extension direction L and the height along the height direction H of the main body portion 30. Multiple screw holes 62 are formed in each side portion 60, 61, and they are fastened and fixed to the main body portion 30 by screws (not shown). In addition, as shown in Figures 5 to 7, a second gas flow passage 63 is formed on the inner surface side (the side facing the main body portion 30) of each side portion 60, 61, which communicates with the first gas flow passage 33 of the main body portion 30.

[0038] Furthermore, in this embodiment, as shown in Figure 4, a plurality of gas ejection holes 64 are arranged at predetermined intervals along the extension direction L of the discharge section 50 to form a gas ejection section 65. These gas ejection sections 65 are located on the outside of both sides in the width direction W, which is perpendicular to the extension direction L of the discharge section 50.

[0039] Further, the opening direction of each gas ejection hole 64, that is, the direction of the opening 64a (see FIG. 6) through which the process gas G flowing through the gas flow path is ejected from the gas ejection hole 64, is inclined so as to face the inside in the width direction W of the discharge portion 50. Each gas ejection hole 64 communicates with the second gas flow path 63 of the side portions 60 and 61, respectively.

[0040] In the case of this embodiment, the plurality of gas ejection holes 64 are arranged at equal intervals along the extension direction L of the discharge portion 50.

[0041] Further, the gas ejection holes 64 in this embodiment are in the shape of circular holes. However, the gas ejection holes may be, for example, polygonal holes such as triangular, quadrangular, pentagonal, hexagonal, or elliptical holes, and are not particularly limited.

[0042] Further, as shown in FIG. 6, at the lower end portions 66 in the height direction H of each of the side portions 60 and 61, on the opposing surface (inner surface) with the main body portion 30, inclined surfaces 67 are respectively formed so as to gradually become thinner toward the main body portion 30 on the opposing surface side of the lower end portions 66 of each of the side portions 60 and 61. And gas ejection portions 65 are respectively formed on the inclined surfaces 67 of each of the side portions 60 and 61. In the case of this embodiment, the gas ejection holes 64 are formed in a direction orthogonal to the inclined surface 67 (see FIG. 6).

[0043] Further, as shown in FIG. 1, in the side portion 60 disposed on the front side of the main body portion 30, a fixing hole 71 having a circular hole shape is formed at the central portion in its extension direction L.

[0044] On the other hand, a support arm 75 is fixed to the side portion 60 disposed on the back side of the main body portion 30. And through this support arm 75, the apparatus main body 20 is supported at a predetermined distance from the processed surface 3 of the object to be processed 1 (see FIG. 7).

[0045] Also, in the apparatus main body 20 of this embodiment, the protruding amount T of the lower end 21 with respect to the lower end 81 of the cover member 80 can be adjusted by an adjustment mechanism. In the case of this embodiment, the support arm 75 can move up and down in the vertical direction by an adjustment mechanism (for example, an electric actuator, a ball screw shaft structure, etc.) not shown. The adjustment mechanism will be described in detail later.

[0046] Next, the cover member 80 will be described in detail. This cover member 80 forms a frame shape that surrounds the entire circumference in the circumferential direction of the apparatus main body 20 and protrudes in a direction closer to the workpiece 1 than the lower end 21 in the height direction H of the apparatus main body 20, and is configured to cover the entire outer circumference of all of the plurality of gas ejection holes 64. In this embodiment, the lower end 81 of the cover member 80 is supported by a support portion not shown so as to be at a predetermined distance (constant distance) from the processing surface 3 of the workpiece 1.

[0047] As shown in FIG. 1, the cover member 80 of this embodiment includes a front cover 82 that covers the front side (side portion 60 side), which is one side portion in the width direction W of the apparatus main body 20, and from both end portions in the extension direction L of the front cover 82, it extends orthogonally toward the back side (side portion 61 side), which is the other side portion in the width direction W of the apparatus main body 20, and side covers 83, 83 that cover the outer surfaces of both end portions in the extension direction L of the apparatus main body 20, and a back cover 84 that connects the side covers 83, 83 to each other and covers the back side of the apparatus main body 20, and has a substantially rectangular long frame shape that conforms to the outer peripheral shape of the apparatus main body 20.

[0048] Note that the portion of the cover member 80 that protrudes a predetermined length from the lower end 21 of the apparatus main body 20, that is, the portion of the cover member 80 that protrudes from the lower end 21 of the apparatus main body 20 and protrudes in a frame shape up to the lower end 81 in the height direction H of the cover member 80 is defined as a skirt portion 85. The skirt portion 85 covers the entire outer circumference of all of the plurality of gas ejection holes 64.

[0049] Furthermore, the space inside the skirt portion 85 of the cover member 80, which is the part that protrudes from the lower end 21 of the main body 20 of the apparatus, is filled with process gas G to form a plasma processing space S that enables plasma processing. Moreover, the skirt portion 85 acts as a partition between the plasma processing space S and the external space located outside (outer circumference) of the skirt portion 85.

[0050] The rear cover 84 consists of a pair of plate-like portions 84a, 84a extending inward from the rear ends of the side covers 83, 83 toward the center of the extension direction L of the cover member 80, and a connecting portion 84b that connects these plate-like portions 84a, 84a to each other on the outer surface. The support arm 75 is inserted and positioned in the space formed between the tips of the pair of plate-like portions 84a, 84a and inside the connecting portion 84b, and acts as a slide guide when the support arm 75 moves up and down in the vertical direction in the lifting structure (see Figures 1, 5 to 7).

[0051] Furthermore, as shown in Figure 1, insertion holes 86 into which fasteners 5 such as screws are inserted are formed in the center of the front cover 82 in the extension direction L, and in the center of the pair of side covers 83, 83 in the width direction W of the cover member 80, at positions aligned with the height direction H. The fasteners 5 are inserted into the insertion holes 86 of the cover member 80 and fixed to the fixing holes 71 of the device body 20, thereby fixing the cover member 80 to the device body 20.

[0052] Furthermore, the amount T of the lower end 21 of the device body 20 protruding relative to the lower end 81 of the cover member 80 having the above configuration can be adjusted by an adjustment mechanism.

[0053] In this embodiment, as described above, the cover member 80 is supported by a support part (not shown) such that its lower end 81 is at a predetermined distance from the workpiece 1 to be processed surface 3, while the device body 20 is raised and lowered vertically via the support arm 75, which is raised and lowered vertically by an adjustment mechanism. As a result, the amount T (see Figures 5-7) of the lower end 21 of the device body 20 protruding relative to the lower end 81 of the cover member 80 (which can also be called the lower end of the skirt portion 85) can be adjusted by the adjustment mechanism.

[0054] For example, if the lower end 21 of the device body 20 is lowered by the lifting mechanism from the state shown in Figures 5 to 7 in a direction that approaches the surface 3 of the workpiece 1, the amount T of the lower end 21 of the device body 20 protruding from the lower end 81 of the cover member 80 decreases compared to the state shown in Figures 5 to 7. As a result, the volume of the plasma processing space S formed in the cover member 80 becomes smaller than the state shown in Figures 5 to 7, and the distance (irradiation distance) of the discharge section 50 to the surface 3 of the workpiece 1 becomes shorter than the state shown in Figures 5 to 7.

[0055] On the other hand, when the lower end 21 of the device body 20 is raised by the lifting mechanism from the state shown in Figures 5 to 7, in a direction away from the surface 3 of the workpiece 1, the amount T of the lower end 21 of the device body 20 protruding from the lower end 81 of the cover member 80 increases compared to the state shown in Figures 5 to 7. As a result, the volume of the plasma processing space S formed in the cover member 80 becomes larger than the state shown in Figures 5 to 7, and the distance (irradiation distance) of the discharge section 50 to the surface 3 of the workpiece 1 becomes longer than the state shown in Figures 5 to 7.

[0056] (Modification) The shape, structure, layout, etc., of each component constituting the plasma processing apparatus in the present invention, namely the apparatus body (main body, side parts), discharge section, gas ejection hole, cover member, adjustment mechanism, etc., are not limited to the above embodiments.

[0057] In this embodiment, the gas ejection section 65, consisting of multiple gas ejection holes 64, is arranged on the outside of both sides in the width direction W of the discharge section 50 (see Figure 4). However, for example, as shown by the dashed line in Figure 4, the gas ejection section 65, consisting of multiple gas ejection holes 64, may be arranged on the outside of both ends in the extension direction L of the discharge section 50. In this case, the gas ejection section 65 will surround almost the entire circumference of the discharge section 50.

[0058] Furthermore, in this embodiment, the gas outlets 64 are circular and arranged in a single row at equal intervals. However, the gas outlets may also be polygonal in shape, including, for example, an ellipse, a triangle, or a square. Moreover, multiple gas outlets may be arranged at predetermined intervals, or arranged in multiple rows instead of a single row.

[0059] In this embodiment, the cover member 80 has a roughly rectangular, elongated frame shape, but the cover member may also have a frame shape such as a roughly square, circular, elliptical, or polygonal shape, as long as it can surround the entire circumference of the main body of the device and cover the outer circumference of all of the multiple gas outlets.

[0060] Furthermore, the adjustment mechanism may be, for example, an air cylinder or an oil cylinder that allows the device body to be raised and lowered, and it is sufficient that the amount of protrusion of the lower end of the device body relative to the lower end of the cover member can be adjusted.

[0061] Furthermore, in this embodiment, the cover member 80 is supported such that its lower end 81 is at a predetermined distance from the workpiece surface 3 of the workpiece 1, while the device body 20 is made vertically adjustable by an adjustment mechanism, allowing the amount of protrusion of the lower end 21 of the device body 20 relative to the lower end 81 of the cover member 80 to be adjusted. However, for example, (1) the device body is supported such that its lower end is at a predetermined distance from the workpiece surface of the workpiece, and the cover member is made vertically adjustable by an adjustment mechanism, allowing the amount of protrusion of the lower end of the device body relative to the lower end of the cover member to be adjusted, or (2) both the device body and the cover member are made vertically adjustable, allowing the amount of protrusion of the lower end of the device body relative to the lower end of the cover member to be adjusted.

[0062] (Effects) Next, the effects of the processing apparatus 10 having the above configuration will be explained.

[0063] First, using the adjustment mechanism, the distance of the lower end 81 of the cover member 80 to the surface 3 of the workpiece 1, and the amount T of the lower end 81 of the cover member 80 protruding from the lower end 21 of the main body of the device 20 are appropriately adjusted, and then, as shown in Figure 7, the main body of the device 20 with the cover member 80 attached is positioned close to the surface 3 of the workpiece 1.

[0064] When process gas G is supplied via connector 32 in the above state, the process gas G flows from gas inlet hole 31 into gas flow passages 33 and 63 inside the apparatus body 20. The process gas G then flows through the first gas flow passage 33 and the second gas flow passage 63 and is ejected from gas ejection holes 64 of gas ejection sections 65 provided on the pair of side sections 60 and 61, filling the plasma processing space S inside the skirt section 85 of the cover member 80.

[0065] In this state, when a voltage is applied to the electrode surface 55 of the discharge section 50 via plugs 34 and 35, layered plasma is generated by creepage discharge along the extension direction L of the discharge surface 56. This allows the surface 3 of the workpiece 1 to be treated to be subjected to appropriate plasma treatment.

[0066] Incidentally, the plasma described above is at a relatively low temperature of 50°C or less. Therefore, the processing apparatus 10 can be used for applications such as surface treatment of objects to be treated, particularly for hydrophilization treatment of fluororesins (PTFE (polytetrafluoroethylene), elongated PTFE, PFA (perfluoroalkoxyalkane)).

[0067] Furthermore, the object to be processed 1 can be a plate-like body such as a substrate, but it may also be a film. If the object to be processed 1 is a film, the processing device 10 can be used to process the surface of the film while feeding the film with multiple rollers (a so-called roll-to-roll method).

[0068] In this embodiment, a voltage is applied to the electrode surface 55 of the discharge unit 50 by a pair of electrodes. However, for example, as shown by the dashed line in Figure 7, the lower electrode 7 on the ground side (GND side) may be placed below the workpiece 1, and the workpiece 1 may be sandwiched between the upper and lower electrodes. Plasma may then be generated to treat the workpiece surface 3, which is the surface of the workpiece 1.

[0069] Furthermore, in this processing apparatus 10, there is a frame-shaped cover member 80 that surrounds the entire circumference of the apparatus body 20 and protrudes in a direction closer to the workpiece 1 than the lower end 21 of the apparatus body 20, and covers the entire outer circumference of the plurality of gas ejection holes 64. As a result, a plasma processing space S is formed inside the protruding portion of the cover member 80, and the cover member 80 effectively suppresses the mixing of the process gas G filled in the plasma processing space S and the outside air present outside the skirt portion 85 of the cover member 80.

[0070] In addition, the adjustment mechanism allows for adjustment of the amount T of the lower end 21 of the device body 20 protruding relative to the lower end 81 of the cover member 80. This makes it possible to change the volume of the plasma processing space S according to the condition of the surface 3 of the workpiece 1, and to adjust the distance of the discharge unit 50 relative to the surface 3 of the workpiece 1 (the shortest distance between the lower end 58 of the discharge unit 50 and the surface 3 of the workpiece 1). As a result, high-quality plasma processing can be applied to the surface 3 of the workpiece 1.

[0071] Furthermore, in this embodiment, the discharge section 50 extends in a predetermined direction, and a plurality of gas ejection holes 64 are arranged at predetermined intervals along the extension direction L of the discharge section 50 to form a gas ejection section 65 (see Figure 4). The gas ejection section 65 is arranged on the outside of both sides in the width direction W perpendicular to the extension direction L of the discharge section 50, and the opening direction of each gas ejection hole 64 constituting the gas ejection section 65 is inclined to face inward in the width direction W perpendicular to the extension direction L of the discharge section 50 (see Figure 6).

[0072] According to the above embodiment, the gas ejection sections 65 are arranged on the outside of both sides in the width direction W of the discharge section 50, and the opening direction of each gas ejection hole 64 is inclined to face inward in the width direction W perpendicular to the extension direction L of the discharge section 50, so that the process gas G is concentrated and ejected toward the center of the discharge section 50 in the width direction. For this reason, for example, by positioning a desired location on the workpiece 1 in the center of the width direction W of the discharge section 50, plasma treatment can be effectively applied to the desired location on the workpiece 1's surface 3.

[0073] Incidentally, if the openings of each gas ejection hole are not inclined but are aligned vertically, the process gas G ejected from the gas ejection section will not easily remain in the plasma processing space S and will easily escape through the lower end opening of the cover member 80. Therefore, even if the surface 3 of the workpiece 1 has large irregularities such as unevenness, it will be difficult to keep the lower end 81 of the cover member 80 away from the surface 3 of the workpiece 1.

[0074] In contrast, in this embodiment, the opening direction of each gas ejection hole 64 of the gas ejection units 65, which are arranged on the outside of both sides in the width direction W of the discharge unit 50, is inclined to face inward in the width direction W perpendicular to the extension direction L of the discharge unit 50. As a result, the process gas G ejected from the pair of gas ejection units 65, 65 remains in the plasma processing space S inside the skirt portion 85 of the cover member 80 and in the center of the discharge unit 50 in the width direction, making it difficult for it to escape from the lower end opening of the cover member 80.

[0075] As a result, it becomes easier to separate the lower end 81 of the cover member 80 from the surface 3 of the workpiece 1, and even if the surface 3 has large irregularities due to unevenness, it can be flexibly adapted to maintain the quality of plasma treatment on the surface 3.

[0076] Furthermore, in this embodiment, the device body 20 has a main body portion 30 that extends in a predetermined direction and forms a gas inlet hole 31 and part of the gas flow passage, and a pair of side portions 60 and 61 that are separate from the main body portion 30 and fixed to both sides in the width direction W perpendicular to the extension direction L of the main body portion 30, forming the remaining part of the gas flow passage and provided with a gas ejection portion 65. At the lower end portion 66 of each side portion 60 and 61, on the surface facing the main body portion 30, an inclined surface 67 is formed which gradually thins out toward the main body portion 30 on the side of the lower end portion 66 of the side portion 60 and 61 facing the main body portion 30, and the gas ejection portion 65 is formed on the inclined surface 67.

[0077] According to the above embodiment, the device body 20 has a structure in which a main body portion 30 and a pair of side portions 60 and 61 separate from the main body portion 30 can be reliably formed inside the device body 20 (if the device body is an integrated structure, it is generally difficult to form a gas flow passage inside).

[0078] Furthermore, since the gas ejection section 65 is formed on the inclined surface 67 formed on the lower end of each side section 60, 61, which is separate from the main body section 30, and on the surface facing the main body section 30, it is easy to form the gas ejection hole 64 even if the inner diameter of the gas ejection hole 64 is minute (if the side sections 60, 61 are injection molded products, it is easy to cut out pins, etc., for forming the gas ejection hole, and if the side sections 60, 61 are machined products, it is easy to process them with a minute drill, etc., for processing the gas ejection hole).

[0079] We tested whether sufficient plasma treatment was performed when a cover member was present and when the amount of protrusion of the lower end of the device body relative to the lower end of the cover member was adjusted using an adjustment mechanism.

[0080] (1) Sample preparation Multiple samples were prepared by applying a silver-graphite composite plating to the surface of a metal piece measuring 25 mm in length and 25 mm in width with a predetermined thickness (4 comparative examples, 4 examples).

[0081] (2) Test method of comparative example (without cover member) The sample was set in a commercially available plasma generator (Cresul Co., Ltd., Caplas gas separation type 150 mm). The power supply of the above device is PW-Smode1618_920_SP (high capacity type), and the electrode is a Caplas 2010WB (10B2) glass epoxy substrate (thickness 2 mm). The above plasma generator has an adjustable distance between the lower end of the device body (lower end of the discharge part) and the surface of the object to be treated (surface of the sample).

[0082] Then, with a frequency of 10 kHz and a voltage of 6 kV, Ar and O ２ Mixed gas (Ar: 3.0 L / min, 0) ２ A plasma at a rate of 0.20 L / min was used to test whether plasma treatment was applied to the sample surface by appropriately varying the plasma irradiation distance from the discharge unit (the distance between the sample surface and the electrode surface of the discharge unit) to 1 mm, 2 mm, 3 mm, and 4 mm. The plasma irradiation time for each sample was 3 seconds. The results are shown in the upper part of Figure 8. Furthermore, if the sample surface was sufficiently treated with plasma, it could be visually confirmed by the oxidation and discoloration of the silver.

[0083] (3) Test method of the example (with cover member) The same plasma generator as in Test Method 1 above was used, except that a cover member was used and the cover member was supported so that the distance between the lower end of the cover member and the surface of the workpiece to be treated (surface of the sample) was 0.5 mm.

[0084] Then, with a frequency of 10 kHz and a voltage of 6 kV, Ar and O ２ Mixed gas (Ar: 3.0 L / min, 0) ２ Plasma at a flow rate of 0.20 L / min was applied to the sample surface by adjusting the amount of protrusion of the lower end of the device body relative to the lower end of the cover member. The plasma irradiation distance from the discharge section (the distance between the sample surface and the electrode surface of the discharge section) was appropriately varied to 1 mm, 2 mm, 3 mm, and 4 mm to test whether plasma treatment was applied to the sample surface. The plasma irradiation time for each sample was 3 seconds. The results are shown in the lower part of Figure 8. Furthermore, if the sample surface was sufficiently treated with plasma, it could be visually confirmed by the oxidation and discoloration of the silver.

[0085] (4) Test Results As shown in the upper part of Figure 8, in the comparative example without a cover member, plasma treatment was applied to the sample surface only when the plasma irradiation distance from the discharge unit was 1 mm, but it was confirmed that plasma treatment was not applied to the sample surface when the plasma irradiation distance from the discharge unit was 2 mm, 3 mm, or 4 mm.

[0086] On the other hand, as shown in the lower part of Figure 8, in the embodiment with a cover member, it was confirmed that plasma treatment was applied to the sample surface regardless of whether the plasma irradiation distance from the discharge unit was 1 mm, 2 mm, 3 mm, or 4 mm. Therefore, it was found that the cover member and adjustment mechanism have an effect, namely that the protruding portion of the cover member can form and maintain a plasma treatment space, and the volume of the plasma treatment space can be appropriately changed according to the surface to be treated, making it possible to apply high-quality plasma treatment to the surface of the object to be treated.

[0087] (5) Spectral analysis by XPS The well-known XPS spectral analysis was performed on the samples of the comparative example and the example, and the O1sXPS spectra of each sample were waveform-separated. The results are shown in Figures 9 and 10(a) and (b). Figure 9 is the case without a cover member, Figure 10(a) is the case with a cover member and a plasma irradiation distance of 1 mm from the discharge part, and Figure 10(b) is the case with a cover member and a plasma irradiation distance of 3 mm from the discharge part.

[0088] In the case shown in Figure 9, only peaks originating from graphite oxide are observed, whereas in the case shown in Figure 10(a), after plasma treatment, Ag is produced due to the oxidation of silver. ２ A peak originating from oxygen was observed. Furthermore, in the case shown in Figure 10(b), it was clear that the silver was effectively oxidized even when magnified to 3 mm after plasma irradiation.

[0089] It should be noted that the present invention is not limited to the embodiments described above, and various modified embodiments are possible within the scope of the gist of the present invention, and such embodiments are also included in the scope of the present invention.

[0090] 1...work to be processed, 3...surface to be processed, 5...fixing device, 10...plasma processing device (processing device), 20...device body, 21...lower end, 30...body part, 31...gas inlet hole, 33...first gas flow passage, 41...fixing hole, 60, 61...side part, 63...second gas flow passage, 64...gas ejection hole, 65...gas ejection part, 66...lower end, 67...inclined surface, 71...fixing hole, 80...cover member, 81...lower end, 86...insertion hole.

Claims

1. A plasma processing apparatus for generating plasma by introducing a process gas and applying a voltage to process the surface of an object to be processed, comprising: an apparatus body having a gas inlet hole for introducing the process gas and a gas flow passage for circulating the process gas; a discharge unit provided at the lower part of the apparatus body for generating the plasma; a plurality of gas ejection holes located at the lower part of the apparatus body and arranged around the discharge unit, communicating with the gas flow passage and ejecting the process gas; a cover member having a frame shape that surrounds the entire circumference of the apparatus body in the circumferential direction and protrudes in a direction closer to the object to be processed than the lower end of the apparatus body, and covering the outer circumference of all of the plurality of gas ejection holes; and an adjustment mechanism that allows adjustment of the amount of protrusion of the lower end of the apparatus body relative to the lower end of the cover member.

2. The plasma processing apparatus according to claim 1, wherein the discharge section extends in a predetermined direction, a plurality of gas ejection holes are arranged at predetermined intervals along the extension direction of the discharge section to constitute a gas ejection section, the gas ejection section is arranged on the outside of both sides in the width direction perpendicular to the extension direction of the discharge section, and the opening direction of each gas ejection hole constituting the gas ejection section is inclined to face inward in the width direction perpendicular to the extension direction of the discharge section.

3. The plasma processing apparatus according to claim 2, wherein the apparatus body comprises a main body portion extending in a predetermined direction and forming part of the gas inlet hole and the gas flow passage, and a pair of side portions separate from the main body portion and fixed to both sides in the width direction perpendicular to the extension direction of the main body portion, forming the remaining part of the gas flow passage and provided with the gas ejection portion, and an inclined surface is formed on the lower end of each side portion facing the main body portion, with the side of the lower end of the side portion facing the main body portion becoming progressively thinner toward the main body portion, and the gas ejection portion is formed on the inclined surface.

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