Plasma treatment apparatus

Abstract

To provide a plasma treatment apparatus which can efficiently modify a surface of a fluororesin substrate even when the fluororesin substrate has a three-dimensional shape.SOLUTION: A plasma treatment apparatus 10 generates plasma, modifies a surface of a substrate 1 which is a fluororesin substrate formed in a three dimensional shape and in which the cross-sectional shape of at least a part of the surface is changed depending on the position by the plasma, and includes a vacuum chamber 11 as a housing part for housing the substrate 1, a plasma generation part 12 for converting a gas in the vacuum chamber 11 into plasma and emitting the plasma from a plasma irradiation part 12a, and an electrode 13 which is arranged behind the substrate 1 arranged in an irradiation direction of the plasma emitted from the plasma irradiation part 12a and to which a predetermined voltage is to be applied, and the electrode 13 is formed in a three dimensional shape.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a plasma processing apparatus for generating plasma in a vacuum state to perform surface treatment on a fluororesin substrate. [Background technology]

[0002] Conventionally, there is a method in which a polytetrafluoroethylene (PTFE) substrate is irradiated with atmospheric plasma to activate the surface, fluorine in the PTFE substrate is replaced with hydroxyl groups derived from moisture in the air, and copper is adhered to the surface of the PTFE substrate to obtain a laminate of the PTFE substrate and copper (for example, see Patent Document 1).

[0003] 11(a) and (b), when the substrate 1 made of PTFE, which is the object to be processed, is formed into a three-dimensional cylindrical shape with a bottom, and the opening 1a is formed with a small diameter as shown in FIG. 11(b), the diameter of the electrode 13 placed inside the substrate becomes small. A DC voltage is applied to the electrode 13 from a holding side power source 14. A fine plasma gun (hereinafter referred to as "FPG") 12 as a plasma generating unit generates plasma of the processing gas, and this plasma is irradiated to the substrate 1 as directional ions and radicals from the plasma irradiation unit 12a. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-225099 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, when the diameter of the electrode 13 disposed in the substrate 1 having a three-dimensional shape becomes smaller, the surface area becomes smaller, and the region in which the ions can be repelled by the positive potential of the electrode 13 becomes smaller. This causes a problem that the substrate 1 cannot be efficiently irradiated with plasma, which may make it difficult to effectively modify the surface of the substrate 1.

[0006] The present application has been made in view of the above circumstances, and an object of the application is to provide a plasma processing apparatus capable of efficiently modifying the surface of a fluororesin substrate even if the fluororesin substrate has a three-dimensional shape. [Means for solving the problem]

[0007] In order to solve the above problem, the invention described in claim 1 is a plasma processing apparatus that generates plasma in a vacuum state and modifies the surface of a cylindrically formed fluororesin substrate, at least a portion of which has a cross-sectional shape that changes depending on the position, by using the plasma, the plasma processing apparatus comprising: a container that contains the fluororesin substrate; a plasma generating unit that converts a gas inside the container into plasma and irradiates the plasma from a plasma irradiation unit; and an electrode that is disposed behind the fluororesin substrate, which is disposed in the irradiation direction of the plasma irradiated from the plasma irradiation unit, and to which a predetermined voltage is applied, the electrode being formed in a three-dimensional shape.

[0008] The invention described in claim 2 has the configuration described in claim 1, and is characterized in that the electrode is formed into a shape that follows the outer shape of the fluororesin substrate, and the cylindrical cross-sectional shape of the fluororesin substrate is a shape rotated around a cylindrical axis of a tube.

[0009] The invention described in claim 3 has the same configuration as described in claim 1, and is characterized in that the electrode is arranged inside the fluororesin substrate with respect to an extension line of the fluororesin substrate in the plasma irradiation area.

[0010] The invention described in claim 4 has the configuration described in claim 1, and is characterized in that the fluororesin substrate is formed into a cylindrical body, the diameter of the cylinder is approximately equal to the distance from the plasma generating part to the tip of the fluororesin substrate, and the distance from the plasma generating part to the tip of the fluororesin substrate is approximately equal to the distance from the tip of the fluororesin substrate to the electrode.

[0011] The invention described in claim 4 is characterized in that, in addition to the configuration described in any one of claims 1 to 4, an introduction means is provided for introducing a hydroxyl group into the fluororesin substrate surface obtained by irradiating the surface of the fluororesin substrate with radicals to remove atoms. Effect of the Invention

[0012] According to the invention described in claim 1, a cylindrical fluororesin substrate, at least a part of which has a cross-sectional shape that changes depending on the position, is disposed in the direction of irradiation of plasma irradiated from a plasma irradiation unit, and an electrode is disposed behind the fluororesin substrate, and the electrode is formed into a three-dimensional shape, so that when the surface of the fluororesin substrate is modified by plasma, the plasma irradiation area is widened and radicals are introduced into a wide area of ​​the fluororesin substrate. This makes it possible to efficiently modify the surface of the fluororesin substrate even if the fluororesin substrate is cylindrical.

[0013] According to the invention described in claim 2, the electrode is formed into a shape that follows the outer shape of the fluororesin substrate, and the cylindrical cross-sectional shape of the fluororesin substrate is a shape rotated around a cylindrical axis, so that the entire potential is the same from the center of the electrode to the open end side, and the potential of the fluororesin substrate is also constant in the circumferential direction, making it possible to uniformly irradiate the fluororesin substrate with hydroxyl radicals. As a result, hydroxyl groups are uniformly introduced into the surface of the fluororesin substrate, and the surface of the fluororesin substrate can be uniformly modified.

[0014] According to the invention recited in claim 3, the electrode is disposed inside the fluororesin substrate with respect to an extension line of the fluororesin substrate in the plasma irradiation region. This prevents any part of the electrode from being exposed in the plasma irradiation region, thereby preventing ions and radicals from concentrating on the exposed part and also preventing the possibility of a ground fault.

[0015] According to the invention recited in claim 4, the fluororesin substrate is formed into a cylinder, the diameter of this cylinder is approximately equal to the distance from the plasma generating unit to the tip of the fluororesin substrate, and the distance from the plasma generating unit to the tip of the fluororesin substrate is approximately equal to the distance from the tip of the fluororesin substrate to the electrode. As a result, when the surface of the fluororesin substrate is modified with plasma, plasma irradiation can be optimized and the range for repelling positive ions in the plasma becomes wider.

[0016] According to the invention recited in claim 5, there is provided an introduction means for introducing hydroxyl groups into the surface of the fluororesin substrate obtained by irradiating the surface of the fluororesin substrate with radicals to eliminate atoms, so that the surface of the fluororesin substrate is made hydrophilic, making it possible to significantly increase the adhesion of the modified surface of the fluororesin substrate. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram illustrating a schematic diagram of a substrate manufacturing system that constitutes the substrate processing apparatus according to the first embodiment. [Diagram 2] 3(a) and 3(b) are perspective views showing a specific shape of a fluororesin substrate in the substrate production system. FIG. [Diagram 3] 4 is a flowchart of processing steps in the above substrate manufacturing system. [Figure 4] FIG. 2 is a diagram showing a processing process in the substrate manufacturing system. [Diagram 5] FIG. 13 is a diagram illustrating a plasma generating unit, a fluororesin substrate, and electrodes that constitute the substrate processing apparatus of the second embodiment. [Figure 6]FIG. 13 is a diagram illustrating a plasma generating unit, a fluororesin substrate, and electrodes that compose the substrate processing apparatus of this embodiment 3. [Figure 7] 1(a) and 1(b) are images showing the surface of the substrate before the surface modification treatment. [Figure 8] 1 is an image showing a substrate surface after a surface modification treatment according to an embodiment of the present invention. [Figure 9] FIG. 2 is an enlarged view of the state in which the surface-modified PTFE and resin (urethane) have been tightly bonded together according to the above embodiment. [Figure 10] FIG. 2 is an enlarged view of the peeled interface in a state where a resin (urethane) that has been tightly bonded to PTFE that has been surface-modified according to the above embodiment has been peeled partway from the PTFE. [Figure 11] 1A and 1B are diagrams illustrating a plasma generating unit, a fluororesin substrate, and electrodes that constitute a conventional substrate processing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] [First embodiment of the invention] FIG. 1 shows the first embodiment.

[0019] As shown in FIG. 1, a substrate processing apparatus 1A according to the first embodiment includes a plasma processing apparatus 10.

[0020] The substrate processing apparatus 1A may be provided with a conveyor-type or robot arm-type transport device (not shown) for transporting the substrate 1 between the plasma processing apparatus 10 and another device.

[0021] [Configuration of plasma processing device] FIG. 1 is a diagram showing a schematic diagram of a plasma processing apparatus according to the first embodiment.

[0022] The plasma processing apparatus 10 shown in FIG. 1 is an apparatus for modifying the surface of a resin substrate. The processing target of the plasma processing apparatus 10 is, for example, the substrate 1 shown in FIG. 1 as a "fluorinated resin substrate". The substrate 1 is a structure made of fluororesin such as PTFE, perfluoroalkoxyalkane (PFA), polychlorotrifluoroethylene resin (PCTFE), etc., and used for various applications. The plasma processing apparatus 10 irradiates the surface of the substrate 1 with plasma to remove at least a part of the atoms of the fluororesin constituting the substrate 1, and then improves the wettability of the surface of the fluororesin by adding hydroxyl groups to the fluororesin. This makes it possible to strengthen the bonding state when bonding another object, for example, a resin layer, to the surface of the substrate 1. Note that, in addition to the resin layer, the object to be bonded to the surface of the substrate 1 may be a metal layer, an adhesive layer, a ceramic layer, or a semiconductor element layer such as Si. Details of the substrate 1 will be described in the section on [Substrate] below.

[0023] The plasma processing apparatus 10 of this embodiment 1 shown in FIG. 1 includes a vacuum chamber 11 as a "container", an FPG 12 as a "plasma generating section", an electrode 13, a holding side power supply 14 as a "first power supply", and a plasma side power supply 15 as a "second power supply".

[0024] The holding-side power supply 14, the electrode 13, and the vacuum chamber 11 form a holding-side circuit 18. Furthermore, the plasma-side power supply 15, the FPG 12, and the vacuum chamber 11 form a plasma-side circuit 19.

[0025] The plasma processing apparatus 10 also includes a first gas introduction section 20 and a second gas introduction section 21 for introducing gas into the vacuum chamber 11, as well as a vacuum pump (not shown) as a "pressure control section" for evacuating the inside of the vacuum chamber 11 to reduce the pressure below atmospheric pressure to create a vacuum state.

[0026] In FIG. 1, some of the scattering directions of ions 22 and radicals 23 inside vacuum chamber 11 are diagrammatically shown by arrows.

[0027] In addition, the vacuum chamber 11 is connected to a ground 24. The ground 24 sets a reference potential for the holding side circuit 18 and the plasma side circuit 19.

[0028] The vacuum chamber 11 is a chamber that can house the fluororesin substrate 1 to be treated, has its interior sealed, and can be evacuated by a vacuum pump (not shown) to reduce the internal pressure below atmospheric pressure to create a vacuum. The vacuum chamber 11 is made of a material, such as steel, that has high rigidity and can withstand the difference in pressure between the inside and outside when the inside is reduced to a vacuum state.

[0029] The FPG 12 is disposed at an upper portion within the vacuum chamber 11, and converts a process gas (not shown) introduced into the vacuum chamber 11 into plasma. For example, the FPG 12 described in International Publication No. 2014 / 175702 can be used. The plasma generated from the FPG 12 preferably contains at least one of nitrogen and argon. The holding-side power supply 14 is a DC power supply, connected to the positive electrode 13 side and ground connected to the vacuum chamber 11 side, and applies a DC voltage (first DC voltage) as a "first voltage" to the holding-side circuit 18. The plasma-side power supply 15 is a DC power supply, connected to the positive electrode to the FPG 12 side and ground connected to the vacuum chamber 11 side, and applies a DC voltage (second DC voltage) as a "second voltage" to the plasma-side circuit 19. The holding-side circuit 18 and the plasma-side circuit 19 are each provided with a switch (not shown) for switching the energized state of the circuit between ON and OFF.

[0030] The gas introduction units 20 and 21 start and stop the introduction of gas into the vacuum chamber 11 and adjust the amount of gas introduced by opening and closing an on-off valve (not shown) and the opening amount. The first gas introduction unit 20 is used to introduce gases used in the "desorption process" described later, such as argon (Ar) gas and nitrogen (N2) gas, into the vacuum chamber 11. The second gas introduction unit 21 is used to introduce gases used in the "introduction process" described later, such as water vapor, into the vacuum chamber 11. Here, the substrate 1 is provided with a rotation shaft 2, and the substrate 1 is configured to be rotatable around the rotation shaft 2. During irradiation of plasma by the FPG 12, the substrate 1 rotates around the rotation shaft 2 so that the surface of the substrate 1 is uniformly treated.

[0031] [Base material] In this embodiment 1, the resin constituting the substrate 1 is not particularly limited as long as it has a hydrophobic surface, and examples thereof include fluororesins such as PTFE, PFA, and PCTFE, polyimide, and LCP. Specifically, in the case of fluororesins, the resin as the material of the substrate 1 contains fluorine and carbon, and the atoms that are detached from the hydrophobic surface of the resin are mainly fluorine and carbon. By providing hydroxyl groups to the activated surface after the molecular bonds are broken, the hydrophobic surface of the fluororesin can be significantly hydrophilized. Moreover, this phenomenon occurs only on the resin surface, and the base material of the resin containing fluorine underneath has high insulation properties and excellent chemical resistance.

[0032] Furthermore, as shown in FIG. 1, the substrate 1 is formed in a cylindrical shape. Specifically, the shape of the substrate 1 is a shape rotated around a rotation axis 2 as a "cylinder axis". The length direction of the substrate 1 is arranged in a direction perpendicular to the irradiation direction of the FPG 12. The cylindrical substrate 1 may be a shape that is reduced in diameter from one end side (left side of the figure) to the other end side (right side of the figure) as shown in FIG. 82(a), or may be a shape in which a small diameter cylinder is provided in a protruding manner on one end side of a large diameter approximately cylindrical shape as shown in FIG. 2(b). In this case, the substrate 1 may be formed in a bottomed cylindrical shape with a bottom surface formed on one end or the other end.

[0033] Furthermore, although not shown, the base material 1 may have a barrel shape that bulges from both ends toward the center, or a shape that tapers from both ends toward the center and is narrowed at the center. In other words, the base material 1 may have a shape in which the cross-sectional shape changes along the axial direction and the size of the inner cross section changes depending on the position in the axial direction.

[0034] In this embodiment 1, the base material 1 is formed in a cylindrical shape, but it is not limited to this and may be formed in a rectangular tubular shape, and it is also applicable to base material 1 in which at least a portion is formed in a three-dimensional shape.

[0035] [Electrode configuration] 1, the electrode 13 in the first embodiment is formed in a semi-cylindrical shape from a conductive member. A holding-side voltage (described later) is applied from a holding-side power source 14 to at least a portion of the electrode 13, which portion depends on the position where the substrate 1 is present.

[0036] The substrate 1 and the electrode 13 are disposed at a position on the rear side of the vacuum chamber 11 (a lower position in FIG. 1) facing the FPG 12 disposed at a position on the front side of the vacuum chamber 11 (an upper position in FIG. 1).

[0037] The electrode 13 is formed in a substantially semi-cylindrical recessed shape corresponding to the cylindrical shape of the outside of the substrate 1, and is formed so that the lower side of the substrate 1 is accommodated in this recessed shape. The electrode 13 is disposed with a certain gap G from the peripheral surface of the substrate 1 when the lower half of the substrate 1 is accommodated. The electrode 13 is disposed behind the substrate 1 disposed in the irradiation direction of the plasma irradiated from the plasma irradiation unit 12a of the FPG 12 as shown in FIG. 5. In the configuration of FIG. 1, the open end 13a of the electrode 13 extends outward beyond the extension line of the substrate 1 in the irradiation area of ​​the FPG 12.

[0038] The electrode 13 is connected to a holding power source 14 and ground 24, and is configured to be switchable between a positive voltage and ground.

[0039] [Processing process] Fig. 3 is a flow chart showing an example of processing steps in the plasma processing apparatus 10 of this embodiment 1. Fig. 4 is a diagram showing a schematic diagram of some of the processing steps in the plasma processing apparatus 10 of this embodiment 1. The processing steps of the plasma processing apparatus 10 of this embodiment 1 will be described with reference to Figs. 3 and 4.

[0040] [Step S1: Desorption process] In the plasma processing device 10 of the substrate processing device 1A, the surface of the substrate 1 is irradiated with plasma from the FPG 12 to desorb at least a portion of the resin atoms on the surface of the substrate 1 (Step S1 in FIG. 2: desorption step).

[0041] Specifically, as shown in [Step 1] of FIG. 4, a vacuum pump (not shown) is operated to create a vacuum environment inside the vacuum chamber 11 at at least 1 / 10 of the pressure achieved when the first gas is introduced, and then an on-off valve (not shown) of the first gas introduction part 20 is opened to introduce a processing gas such as nitrogen or argon into the vacuum chamber 11, thereby bringing the inside of the vacuum chamber 11 to a predetermined pressure (for example, 0.05 Pa or more and 0.3 Pa or less, preferably about 0.3 Pa).

[0042] After the processing gas is introduced into the vacuum chamber 11, a switch (not shown) of the plasma side circuit 19 is turned ON to turn on the FPG 12, and as shown in [Step 2] of Fig. 4, plasma of the processing gas of nitrogen or argon introduced into the vacuum chamber 11 is generated by the action of the FPG 12. As shown in Fig. 1, the generated ions 22 and radicals 23 collide with the substrate 1, and resin atoms are desorbed from the surface of the substrate 1 mainly due to the impact of the collision of the ions 22. Then, the switch (not shown) of the plasma side circuit 19 is turned OFF to turn off the FPG 12, and the desorption process is completed.

[0043] In the detachment step, the holding side power supply 14 is turned off, and the electrode 13 is switched so as to be connected to the ground 24 (not shown).

[0044] When resin atoms are detached from the surface of the substrate 1, the atoms cause the pressure inside the vacuum chamber 11 to rise, and even if the pressure is set to, for example, 0.3 Pa, it becomes greater than 0.3 Pa. If the pressure exceeds 0.3 Pa, the state of the plasma irradiated from the FPG 12 changes from dark discharge to glow discharge, making it impossible to achieve stable processing. Therefore, an aperture diaphragm (not shown) installed between the vacuum pump and the vacuum chamber 11 is opened to increase the amount of vacuum drawn, thereby maintaining 0.3 Pa.

[0045] [Step S2: Introduction process] In the plasma processing apparatus 10, after the desorption step, a hydroxyl group is added to the resin constituting the base material 1, thereby improving the wettability of the surface of the base material 1 (Step S2 in FIG. 3, introduction step).

[0046] Before the introduction step begins, a vacuum pump (not shown) is operated to create a vacuum environment inside the vacuum chamber 11 at at least 1 / 10 of the pressure realized when the second gas is introduced. At this time, atoms of the resin are discharged from the nitrogen or argon processing gas used in the desorption step and from the surface of the substrate 1. Neither the retention side circuit 18 nor the plasma side circuit 19 is energized.

[0047] Next, the holding circuit 18 is energized, and a positive voltage is applied to the electrode 13 as a holding voltage, thereby starting the introduction step.

[0048] In the introduction step, the holding side circuit 18 is turned ON, and the voltage of the holding side power supply 14 is applied to the electrode 13, and the opening and closing valve (not shown) of the second gas introduction part 21 is opened as shown in [Step 3] of FIG. 4 to introduce water vapor of the processing gas into the vacuum chamber 11. In this way, the inside of the vacuum chamber 11 is made to have a predetermined pressure (a pressure that allows radicals to be suitably attached to the surface of the substrate 1, for example, a pressure of 30% to 75% of the pressure in the desorption step of step S1). When the water vapor of the processing gas is filled in the vacuum chamber 11 and the pressure becomes suitable for processing, the plasma side circuit 19 is turned ON and the plasma side power supply 15 is energized to the FPG 12, whereby plasma of the processing gas filled in the vacuum chamber 11 is generated. The timing of introducing the processing gas may be before energizing the holding side circuit 18.

[0049] At this time, it is desirable that the voltage of the holding side circuit 18 is smaller than the voltage of the plasma side circuit 19. Specifically, it is more desirable that the first DC voltage from the holding side power supply 14 is 40% or more of the second DC voltage applied from the plasma side power supply 15 to the FPG 12, and is smaller than the second DC voltage.

[0050] The holding side circuit 18 and the plasma side circuit 19 may be controlled by the amount of current instead of or in addition to the magnitude of the voltage. Specifically, it is preferable that the amount of current as the "first current" supplied from the holding side power supply 14 to the holding side circuit 18 is equal to or greater than the amount of current as the "second current" supplied from the plasma side power supply 15 to the plasma side circuit 19.

[0051] In this state, when plasma is generated in the process gas in the vacuum chamber 11 by the FPG 12, most of the positive ions 22 in the plasma move in the direction of the vacuum chamber 11 where the potential difference is large. Here, the electrode 13 is formed in a semi-cylindrical shape and is arranged to surround the circumferential surface of the substrate 1 with a certain gap G therebetween, so that the range in which the positive ions 22 in the plasma are repelled is wide, and most of the ions 22 can be efficiently moved in the direction of the vacuum chamber 11.

[0052] On the other hand, radicals 23 (hydroxyl radicals) having no polarity in the plasma are irradiated to the substrate 1. By irradiating the substrate 1 with the radicals 23 (hydroxyl radicals), hydroxyl groups (-OH) are introduced to the surface of the substrate 1. Then, the retention side circuit 18 and the plasma side circuit 19 are disconnected, thereby completing the introduction process.

[0053] It is desirable that the surface of the base material 1 into which the hydroxyl groups have been introduced in the introduction step has a contact angle with water of 10° or less, more desirably 6° or less. In this way, in the bonding step (step S3) described below, a resin or the like will adhere firmly to the surface of the base material 1. If an electronic circuit is manufactured using this base material 1, a metal film or metal plating will adhere firmly to the surface of the base material 1.

[0054] In addition, in the introduction step, a process gas other than water vapor is introduced into the vacuum chamber 11 (for example, a process gas such as nitrogen gas or argon gas is introduced again), and current is passed through the FPG 12 to generate plasma of the process gas filled in the vacuum chamber 11, and non-polar radicals 23 in the plasma (such as nitrogen radicals generated by nitrogen gas and argon radicals generated by argon gas) are irradiated onto the substrate 1 to generate chemical bonds of elements on the surface of the substrate 1 (for example, carbon-nitrogen bonds (CN bonds) by nitrogen radicals, and carbon-carbon bonds (CC bonds) by argon radicals), and the time during which the contact angle of the surface of the substrate 1 with water becomes small can be extended as shown in [Step 4] of Figure 4.

[0055] Then, as shown in [Step 5] of Figure 4, outside air is introduced into the vacuum chamber 11 to make the inside of the vacuum chamber 11 atmospheric pressure. When bonding, the resin is heated to a temperature where it becomes soft, and pressure is applied to bond them together. An example of bonding is shown in Figure 9.

[0056] [Step S3: Bonding process] In the plasma processing apparatus 10, the base material 1 that has completed the introduction step is transferred to a bonding device (not shown) or the like, where a step of bonding another member to the base material 1 is performed (a bonding step).

[0057] For example, in the bonding step, a bonding device (not shown) bonds the base material 1 with a predetermined resin.

[0058] Also, for example, in the bonding process, the base material 1 is transported to various bonding devices (not shown) and a process of bonding other resins to the surface of the base material 1 is performed as necessary. Bonding of other resins to the base material 1 is performed by various methods as necessary, such as bonding with an adhesive, thermal welding, bonding by chemical modification of the base material 1 with a chemical, etc.

[0059] After the above steps S1 to S3, various necessary steps are further carried out on the base material 1, and a substrate (not shown) using the base material 1 is manufactured.

[0060] [Effects] As described above, in this embodiment 1, the cylindrical substrate 1 is disposed in the direction of the plasma emitted from the FPG 12, and the electrode 13 is disposed behind the substrate 1. The electrode 13 is formed in a three-dimensional shape, and is disposed so as to surround a part of the circumferential surface of the substrate 1. This makes it possible to broaden the region irradiated with the plasma when modifying the surface of the substrate 1 with the plasma, and to broaden the range in which the positive ions 22 in the plasma are repelled. As a result, the radicals 23 (hydroxyl radicals) are introduced into the substrate 1 over a wide area, and it becomes possible to efficiently modify the surface of the substrate 1 even if the substrate 1 has a three-dimensional shape.

[0061] In this embodiment 1, the electrode 13 is formed in a shape that follows the outer shape of the substrate 1, so that the potential from the center of the electrode 13 to the opening end 13a side is the same, and the potential of the substrate 1 is also constant in the circumferential direction, so that it is possible to uniformly irradiate the substrate 1 with the radicals 23 (hydroxyl radicals). This allows the hydroxyl groups to be uniformly introduced into the surface of the substrate 1, and the surface of the substrate 1 can be uniformly modified.

[0062] [Embodiment 2 of the invention] FIG. 4 shows a second embodiment of the present invention.

[0063] 4 is a schematic diagram showing an FPG 12, a substrate 1, and an electrode 13 that constitute a plasma processing device 10 of a substrate processing device 1A according to embodiment 2. Note that in the following embodiments, parts that are the same as or correspond to those in embodiment 1 are given the same reference numerals, and different configurations and effects will be described.

[0064] [Electrode configuration] As shown in FIG. 5, the base material 1 is formed in a cylindrical shape as in the first embodiment, and is disposed so that its length direction is perpendicular to the FPG 12 .

[0065] The electrode 13 of the second embodiment is formed to have an arc-shaped longitudinal section, and is formed to have a curvature with a certain gap G along the outer shape of the substrate 1, similar to the electrode 13 of the first embodiment. The electrode 13 is disposed inside the substrate 1 from an extension line of the substrate 1 in the region irradiated with plasma by the FPG 12. Specifically, the electrode 13 is formed to have an angle range narrower than that of the electrode 13 of the first embodiment so that the opening end 13a is not exposed to the outside from the region irradiated with plasma on the substrate 1.

[0066] [Effects] In this embodiment 2, the electrode 13 is positioned inside the substrate 1, further inward than the extension line of the substrate 1, in the plasma irradiation area by the FPG 12, so that the opening end 13a of the electrode 13 is not exposed within the plasma irradiation area.

[0067] 3, the ions 22 do not concentrate on the open end 13a of the electrode 13, and the ions 22 can be reliably concentrated on the substrate 1. Furthermore, the substrate 1 is rotated about the rotation axis 2. As a result, the resin atoms can be uniformly and effectively released from the surface of the substrate 1 as a whole, and the possibility of a ground fault can also be prevented.

[0068] Furthermore, in the introduction process, the radicals 23 are prevented from concentrating at the opening end 13a of the electrode 13, and hydroxyl groups are reliably imparted to the resin constituting the substrate 1, thereby significantly improving the effect of improving the wettability of the surface of the substrate 1.

[0069] Furthermore, in this embodiment 2, the electrode 13 is formed in an arc-shaped longitudinal section and has a curvature with a certain gap G along the outer shape of the substrate 1, so that the range in which the positive ions 22 in the plasma are repelled becomes wide, and most of the ions 22 can be efficiently moved toward the vacuum chamber 11. As a result, the radicals 23 (hydroxyl radicals) are introduced into the substrate 1 over a wide range, and even if the substrate 1 has a three-dimensional shape, the surface of the substrate 1 can be efficiently modified.

[0070] [Embodiment 3 of the invention] FIG. 6 shows a third embodiment of the present invention.

[0071] FIG. 6 is a diagram showing a schematic diagram of an FPG 12, a substrate 1, and an electrode 13 that constitute a plasma processing apparatus 10 of a substrate processing apparatus 1A according to the third embodiment.

[0072] As shown in Figure 6, this embodiment 3 specifies the distance L1 from the FPG 12 to the tip 1b of the substrate 1, the diameter D of the substrate 1, and the distance L2 from the tip 1b of the substrate 1 to the part of the electrode 13 that is farthest from the FPG 12.

[0073] Specifically, the distance L1 from the FPG 12 to the tip 1b of the substrate 1 is approximately equal to the diameter D of the substrate 1, and the distance L1 from the FPG 12 to the tip 1b of the substrate 1 is approximately equal to the distance L2 from the tip 1b of the substrate 1 to the part of the electrode 13 that is farthest from the FPG 12.

[0074] [Effects] In this embodiment 3, the distance L1 from the FPG 12 to the tip 1b of the substrate 1 is approximately equal to the diameter D of the substrate 1, and the distance L1 from the FPG 12 to the tip 1b of the substrate 1 is approximately equal to the distance L2 from the tip 1b of the substrate 1 to the part of the electrode 13 that is farthest from the FPG 12. Therefore, when the surface of the substrate 1 is modified by plasma, the irradiation of the plasma can be optimized, and the range in which the positive ions 22 in the plasma are repelled becomes wider. As a result, the radicals 23 (hydroxyl radicals) are introduced into the substrate 1 over a wider range, and the surface of the substrate 1 can be modified efficiently even if the substrate 1 has a three-dimensional shape.

[0075] [Example] Next, an example of the plasma processing apparatus 10 will be described. In this example, the substrate 1 according to the present embodiment is used as a sample and surface-modified in the plasma processing apparatus 10 according to the present embodiment, and bonding of other resin to the substrate 1 and peeling of the resin are verified.

[0076] 7(a) and (b) are images showing the substrate surface before the surface modification treatment, and Fig. 8 is an image showing the substrate surface after the surface modification treatment by the embodiment of the plasma processing apparatus 10.

[0077] In this embodiment, the material of the substrate 1 as the object to be modified is polytetrafluoroethylene (PTFE), and the shape is a cylinder (see Fig. 2(a) and (b)). The surface to be modified using this embodiment is the outer surface.

[0078] Here, PTFE, which is a fluororesin, is chemically stable. When the thickness of the substrate 1 is made small, the substrate 1 made of sheet-like PTFE can be molded into various three-dimensional shapes. However, since the substrate 1 made of such a small thickness is very soft, it becomes difficult to maintain the three-dimensional shape.

[0079] For example, when a cylindrical substrate 1 is molded from thin PTFE, the substrate 1 is often too soft to stand on its own while maintaining the molded three-dimensional shape.

[0080] Therefore, in this embodiment, as described later, a verification was carried out as to whether it is possible to bond another resin to the surface of the PTFE substrate 1 in a laminated state, increase the rigidity of the substrate 1, and maintain a three-dimensional shape in a self-supporting state. In this embodiment, the verification was carried out in a state where the PTFE constituting the substrate 1 was surface-modified in order to increase the adhesion with the other resin that maintains the shape when it is self-supporting. Also, as shown in FIG. 8, a plurality of thin, substantially rectangular PTFE plates 32 are attached to the side of a cylindrical base 31 to form a substrate 1 having a substantially cylindrical shape.

[0081] The plasma processing apparatus 10 of this embodiment employs a cluster processing method as a processing method, for example, in which desorption processing and introduction processing are performed in the same chamber. When transporting the substrate 1, the opening of the cylindrical substrate 1 is held and transported at high speed. When performing a modification process using the plasma processing apparatus 10, the opening of the cylindrical substrate 1 is held and rotated, and the outer surface is uniformly irradiated with plasma.

[0082] Moreover, the electrode 13 is formed to have an arc-shaped vertical cross section (120 to 240 degrees) along the outer circumferential shape of the cylindrical substrate 1, and is disposed so that the gap G from the substrate 1 is in the range of 2 to 20 mm. Note that the range of this gap G can be changed as appropriate.

[0083] 7(a) and (b) show scanning electron microscope (SEM) images of a cylindrical sample before modification processing is performed using the above-described plasma processing apparatus 10. Fig. 7(b) shows an image of the surface of the substrate 1 in (a) photographed at a higher magnification (see the scale at the lower right of the images in Fig. 7(a)-(b)).

[0084] As shown in the images in Figure 7, in the image before the modification treatment, traces 37 like those made by cutting were observed on the surface. As shown in Figure 7(b), when the surface of the part without traces 37 is enlarged, it is smooth. Traces 37 are generated in the processing and introduction processes, and therefore it is difficult to impart stable hydrophilicity when hydroxyl groups (-OH) are introduced to the surface of the sample, and the wettability of the resin surface is poor. Therefore, although such traces 37 can be expected to have an anchor effect due to the unevenness, they are disadvantageous for firmly bonding other resins. It is desirable for the surface to be modified to be smooth.

[0085] 8 to 10 show images of a cylindrical sample after modification processing using the plasma processing apparatus 10 of this embodiment. As shown in Fig. 8, the state of the substrate 1 as a sample and the bonding and peeling states between the substrate 1 and urethane 35, which is another resin, were photographed at measurement position 34, which is the middle part of the sample in the height direction. Although not shown, the bonding and peeling states between the substrate 1 as a sample and the copper film, which were similarly surface modified, were also verified for comparison.

[0086] After the resin atoms are desorbed from the surface of the sample through the desorption step as described above, a hydroxyl group (-OH) is introduced to the surface of the sample in the introduction step to impart stable hydrophilicity.

[0087] FIG. 7 shows an enlarged photograph of the surface of the substrate 1 before such surface modification, and FIG. 8 shows an enlarged view of the surface of the substrate 1 after the surface modification. As shown in FIG. 8, the surface of the substrate 1 after the surface modification has folds 33 formed on the surface by the plasma, which was smooth before the modification. The folds 33 form many small irregular shapes on the surface of the substrate 1. Large cracks and steps are traces 37, and cannot be removed by surface modification. It can be understood that the surface modification of the present invention is a phenomenon occurring near the surface. It can be seen that the surface modification has been achieved within the range where the ion beam reaches, even with the traces 37. It was found that when the folds 33 are formed on the surface of the substrate 1, the adhesion of the resin to the surface of the substrate 1 is further improved compared to the substrate 1 whose surface is in the state shown in FIG.

[0088] Next, the PTFE substrate 1 surface-modified as described above was bonded to a resin. Urethane was selected as the resin. The urethane 35 and the PTFE substrate 1 were bonded together by applying pressure while heating. The PTFE substrate 1 surface-modified and the urethane 35 were directly stacked on top of each other and bonded together without applying any adhesive or primer to the surface of the PTFE substrate 1. The heating temperature was near the temperature at which the urethane softens. It is desirable to set this heating temperature to a lower temperature than that of the PTFE substrate 1. Resins other than the urethane 35 can also be bonded together if they have a lower melting point than the PTFE substrate 1.

[0089] The principle behind the tight bonding is that when the PTFE base material 1 and the urethane 35 are directly stacked and heated and pressurized, the urethane 35, which has a low melting point, softens as shown in Fig. 9, and the urethane penetrates into every nook and cranny between the folds 33 of the PTFE base material 1 generated by surface modification. The resin of the present invention is not limited to urethane, and may be, for example, polyvinyl chloride (PVC), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS) or polypropylene (PP), which are commonly used for resin containers.

[0090] When the closely bonded urethane 35 and PTFE substrate 1 were peeled off, the surface was observed to have broken at the brittle layer of PTFE, with the PTFE substrate 1 adhering to the surface of the urethane 35. The PTFE adhering to the urethane 35 had no visible folds 33, and was uneven. Meanwhile, on the PTFE substrate 1 side, the base of the folds 33 of the PTFE substrate 1 was torn off, and there were traces of PTFE fiberization. This condition spread over the entire surface, and was uniform with no difference no matter which part was observed, so it can be said that the adhesion was stable over the entire surface. The peel strength was 1.2 N / mm.

[0091] When the experiment was conducted under conditions of lower heating temperature and reduced pressure, there were areas where the urethane 35 and PTFE base material 1 were not in contact. The folds 33 from the surface modification remain on the PTFE base material 1 side of the non-contact areas. There is also no unevenness on the surface of the urethane 35 side in the non-contact areas. Insufficient heating and pressure results in partial poor adhesion and reduced adhesion. It was found that when heating and pressure are applied, the softening of the urethane 35 contributes to adhesion, and that the effect of heating is large.

[0092] The cross section of the bonded surface between the urethane 35 and the PTFE substrate 1, which had a peel strength of 1.2 N / mm, was observed. As shown in FIG. 9, the interface between the urethane 35 and the PTFE substrate 1 is comb-shaped. Contrary to the expectation that the folds 33 of the PTFE substrate 1 generated by the surface modification would be crushed by pressure, the folds 33 remained. The shape of the folds 33 is not a sharp mountain shape like when PTFE is copper plated, but an uneven shape with vertical walls. It is believed that the folds 33 generated by the surface modification were somewhat crushed by pressure. These vertical folds 33 also have no gaps at the interface, and the height of the folds 33 is the same as in the case of copper plating, so it is believed that a high adhesive force was generated. It is believed that the height of the folds 33 after the resin adhesion has not changed significantly from the folds 33 at the time of generation by the surface modification.

[0093] When the peel strength was measured after bonding the copper film to the substrate 1 as a surface-modified sample, the peel strength of the copper film was only slightly lower than that of the urethane 35. The reason why the peel strength of the urethane 35 was only slightly higher than that of the copper film is because the fracture occurred not at the interface between the urethane 35 and the PTFE substrate 1, but at the base of the folds 33 of the PTFE substrate 1, just as in the case of the copper film. It can be said that improving the fragility of the base of the folds 33 is the key to adhesion. Although the PTFE substrate 1 is heated in the case of the urethane 35, the effect on fragility is thought to be small.

[0094] The peeling of the adhered urethane 35 was stopped midway and the peeling interface between the urethane 35 side and the PTFE substrate 1 side was observed. As shown in FIG. 10, the pleats 33 of the PTFE substrate 1 were pulled toward the urethane 35 side, and fibrous PTFE 36 was observed. This fibrous PTFE 36 seemed to have a greater amount of fiberization than the copper film. The pleats 33 were stretched and fiberized, and the pieces that were torn off beyond the limit were attached to the urethane 35, and the amount of the attached pieces was larger than that of the copper film and formed a mass. Since a large amount of fibrous PTFE substrate 1 was generated, it indicates that strong adhesion was generated. The fiberization phenomenon is not related to surface modification, and it also occurs on the fracture surface when PTFE is simply tensile tested. When PTFE is torn off microscopically, thread-like things are generated, which looks like fiberization. However, when the evaluation was performed by stopping the peeling midway, there is a correlation between the number of remaining fibrous PTFE 36 and the peel strength (adhesion).

[0095] In the above-described examples, it has been demonstrated that the substrate 1 made of surface-modified PTFE and the urethane 35 as a resin strongly adhere to each other.

[0096] It goes without saying that the above-mentioned embodiments are merely examples of the present invention, and do not mean that the present invention is limited to only the above-mentioned embodiments. In other words, various modifications and applications of the above-mentioned embodiments are possible as long as they are suitable for solving the problems of the present invention.

[0097] For example, in each of the above embodiments, since the substrate 1 is cylindrical, the electrode 13 is also formed in an arc-shaped longitudinal section and is formed with a curvature having a certain gap G along the outer shape of the substrate 1, but without being limited thereto, for example, if the substrate 1 is formed in a rectangular tube shape, the electrode 13 may also be formed in a rectangular tube shape longitudinal section so as to have a certain gap G along the outer shape of the substrate 1. Even when formed in this way, it is preferable to dispose the electrode 13 on the inside of the substrate 1 relative to the extension line of the substrate 1 in the region irradiated with plasma by the FPG 12 as described above.

[0098] In addition, the substrate processing apparatus 1A in each of the above embodiments may also be equipped with various devices (such as a sputtering device) for forming metal foil on the substrate 1, a plating device for plating the substrate 1, a developing device for forming a circuit pattern on the substrate 1, and a pattern etching device.

[0099] Furthermore, in the above-mentioned embodiments and examples, the substrate 1 is formed into a cylindrical shape with a bottom, but the present invention can also be applied to a substrate 1 formed into a flat plate shape as long as the material of the substrate 1 is PTFE, and the PTFE is surface-modified as described above and bonded closely to another resin, for example, urethane. In this case, the substrate processing device used is substrate processing device 1A shown in FIG. 1.

[0100] In the examples, PTFE, a representative fluororesin, is used, but the present invention is not limited to PTFE. For example, the present invention can also be applied to PFA, FEP, and PCTFE, although the time required for surface modification differs. [Industrial Applicability]

[0101] The plasma processing apparatus of each embodiment is used for a high-performance container in which, for example, a bottomed cylindrical bottle shape is formed of a three-dimensional base material made of fluorine, and the inside and outside of the bottle are made of different resin materials. The inside has excellent chemical resistance because of the fluorine, and has a function that could not be realized by the outer resin alone. If PFA is used as the material, a permeable bottle that allows the contents to be confirmed can be realized. Even PTFE can be used as a permeable high-performance bottle if it is made 50 μm or less. Furthermore, if PCTEF is used, a high-performance bottle with excellent gas permeability can be obtained. It can be used not only in resin bottles, but also in circuit boards with three-dimensional shapes by copper plating the surface of fluororesin, and can also be used in circuit boards with complex shapes for use on the human body. PTFE is a stable resin that does not affect the human body, so it is not only suitable for use on the human body, but also as a small circuit board that communicates high-speed and large-capacity information. Since the relative dielectric constant of fluororesin is second only to air, fluororesin boards are particularly suitable as a material for high-frequency boards. Compared to circuit boards made of other general materials, circuit boards made of fluororesin have a low relative dielectric constant and dielectric tangent, and have small dielectric loss, even when high-frequency current is passed through them.

[0102] When the plasma processing apparatus of each embodiment is applied to the manufacture of fluororesin substrates, it is possible to provide circuit substrates with complex shapes that can withstand use in high frequency bands. This technology applicable to use in high frequency bands can also be applied to communication substrates in homes, factories, and transportation equipment such as automobiles and drones.

[0103] The plasma processing apparatus of each embodiment can also be used to manufacture substrates in various fields other than those mentioned above. Furthermore, the plasma processing apparatus of each embodiment can also be applied to manufacture various members and base materials that require surface modification other than the base materials of electronic components, such as medical instruments such as endoscopes and packages for medicines, machine parts, optical instrument parts such as cameras and microscopes, parts for automobiles, ships and aerospace industry equipment, furniture, tableware and decorative items. [Explanation of symbols]

[0104] 1...Base material (fluorinated resin base material) 1A···Substrate processing equipment 1a...Opening 1b...Tip 2. Rotating shaft 10. Plasma treatment device 11 Vacuum chamber (container) 12 FPG (plasma generating unit) 12a Plasma irradiation section 13...electrode 13a...Open end 14... Holding side power supply 15 Plasma side power supply 18... Holding side circuit 19 Plasma side circuit 20... First gas inlet 21...Second gas inlet 22. Ion 23 Radical 24 Grand

Claims

1. A plasma processing apparatus that generates plasma in a vacuum state and modifies a surface of a cylindrical fluororesin substrate, at least a portion of which has a cross-sectional shape that varies depending on the position, using the plasma, comprising: a housing portion for housing the fluororesin substrate; a plasma generating unit that converts the gas inside the container into plasma and irradiates the plasma from a plasma irradiating unit; an electrode to which a predetermined voltage is applied, the electrode being disposed behind the fluororesin substrate disposed in a direction in which the plasma is irradiated from the plasma irradiation unit; 4. The plasma processing apparatus according to claim 1, wherein the electrode is formed in a three-dimensional shape.

2. 2. The plasma processing apparatus according to claim 1, wherein the electrode is formed into a shape that conforms to an outer shape of the fluororesin substrate, and the cylindrical shape as the cross-sectional shape of the fluororesin substrate is a shape rotated around a cylindrical axis of a tube.

3. 2 . The plasma processing apparatus according to claim 1 , wherein the electrode is disposed inside the fluororesin substrate with respect to an extension line of the fluororesin substrate in the plasma irradiation area.

4. 2. The plasma processing apparatus according to claim 1, wherein the fluororesin substrate is formed into a cylindrical body, a diameter of the cylinder is approximately equal to a distance from the plasma generating unit to a tip end of the fluororesin substrate, and a distance from the plasma generating unit to the tip end of the fluororesin substrate is approximately equal to a distance from the tip end of the fluororesin substrate to the electrode.

5. 5. The plasma processing apparatus according to claim 1, further comprising an introduction means for introducing hydroxyl groups into the surface of the fluororesin substrate from which atoms have been removed by irradiating the surface of the fluororesin substrate with radicals.

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