High frequency antenna

Abstract

This invention provides a high-frequency antenna capable of efficiently carrying a large current even at high frequencies used for plasma generation, and a plasma processing apparatus using the high-frequency antenna. The high-frequency antenna 11 of this invention is constructed of a metal fiber sheet. The plasma processing apparatus of this invention includes: a vacuum container 21 having an opening 213 in its wall 211; a high-frequency antenna 11 disposed in the opening 213, constructed of a metal fiber sheet; and a dielectric protective plate 12 disposed on the inner side of the vacuum container 21, which hermetically seals the opening 213. The high-frequency antenna 11, constructed of a metal fiber sheet, has a larger surface area than a high-frequency antenna constructed of a metal plate of the same shape, and therefore has a lower impedance relative to the high-frequency current. Therefore, the high-frequency current commonly used for plasma generation (e.g., 13.56 MHz) can be carried out more efficiently in a large current form.

Description

[Technical Field]

[0001] The present invention relates to a high-frequency antenna and a plasma processing apparatus using the high-frequency antenna. [Previous Technology]

[0002] In an inductively coupled plasma processing device, in order to increase the density of plasma generated in the device, it is necessary to increase the intensity of the electromagnetic field by passing a large current through a high-frequency antenna.

[0003] As an example of a high-frequency antenna capable of carrying large currents, Patent Document 1 describes a planar high-frequency antenna constructed from a rectangular metal plate. In such a planar high-frequency antenna, by flowing current between the two opposite sides of the rectangle, the impedance is reduced compared to the case where a linear high-frequency antenna is wired in the same plane, allowing a larger current to flow.

[0004] In Patent Document 1, the planar high-frequency antenna is disposed at the opening of the vacuum container and also serves as a cover to block the opening. A dielectric protective plate is provided inside the vacuum container of the planar high-frequency antenna to protect it from the effects of plasma generated inside the vacuum container. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. WO2009 / 142016 [Summary of the Invention]

[0006] [Problem to be solved by the invention] In a conductor, the larger the cross-sectional area in the direction of current flow, the larger the current can flow. However, in the case of high-frequency current, due to the skin effect, the current only flows near the surface, and the effect of increasing the cross-sectional area to increase the current is very limited.

[0007] The problem this invention aims to solve is to provide a high-frequency antenna that can efficiently carry a large current even in the high frequencies used to generate plasma, and a plasma processing apparatus using the same high-frequency antenna. [Means for Solving the Problem]

[0008] The high-frequency antenna of the present invention, which is made to solve the above-mentioned problems, is composed of a metal fiber sheet.

[0009] The plasma processing apparatus of the present invention comprises: a) a vacuum container having an opening in its wall; b) a high-frequency antenna disposed in the opening and made of a metal fiber sheet; and c) a dielectric protective plate disposed on the inner side of the vacuum container, in a manner that hermetically seals the opening.

[0010] In this invention, a metal fiber sheet is used as a high-frequency antenna. The metal fiber sheet is a sheet-like material composed of metal fibers. As such a metal fiber sheet, a non-woven fabric with randomly arranged metal fibers can be used. Preferably, at least a portion of the metal fibers are bonded together. Furthermore, it is preferable that the metal fiber sheet has a porous structure.

[0011] A high-frequency antenna made of a metal fiber sheet has a larger surface area than a high-frequency antenna made of a metal plate of the same shape as the metal fiber sheet, and therefore has a lower impedance to the high-frequency current. Therefore, the high-frequency current (e.g., 13.56 MHz) commonly used for plasma generation can be flowed more efficiently in the form of a large current.

[0012] In a metal fiber sheet, the proportion of metal fibers in the overall volume is called the "duty cycle". If the duty cycle is too low, the surface area becomes smaller, and the high-frequency current that can flow also becomes smaller. On the other hand, if the duty cycle is too high, the surface area becomes smaller because the portion of the metal fiber in contact with other metal fibers becomes larger, and the high-frequency current that can flow also becomes smaller. Furthermore, since each metal fiber expands and contracts according to temperature changes, the duty cycle varies with temperature. Considering these points, it is preferable that the duty cycle of the metal fiber sheet used in this invention is 5% to 60% at a temperature of 25°C.

[0013] In the plasma processing apparatus of the present invention, a dielectric protective plate is provided on the inner side of the vacuum container, closer to the surface than the high-frequency antenna made of metal fiber sheets. The protective plate of the present invention serves to protect the high-frequency antenna from the effects of plasma generated inside the vacuum container and to hermetically seal the opening of the vacuum container. While the task of hermetically sealing the opening of the vacuum container is conventionally performed by a high-frequency antenna made of a metal plate, since a high-frequency antenna made of metal fiber sheets is not hermetically airtight, in the present invention, the protective plate replaces the high-frequency antenna in performing the task of hermetically sealing the opening.

[0014] Preferably, the plasma processing apparatus of the present invention further includes a strength reinforcing plate made of an insulating material on the side of the aforementioned high-frequency antenna opposite to the aforementioned internal side, wherein the aforementioned protective plate is in close contact with the high-frequency antenna, and the high-frequency antenna is in close contact with the strength reinforcing plate. Therefore, since the protective plate, the high-frequency antenna, and the strength reinforcing plate function as a single unit to airtightly seal the opening of the vacuum container, the mechanical strength is improved compared to the case where the opening is sealed only by the protective plate.

[0015] Preferably, in the configuration having the aforementioned strength reinforcing plate, the aforementioned protective plate is thinner than the strength reinforcing plate. According to this configuration, while ensuring the mechanical strength of the entire cover that blocks the opening of the vacuum container, the intensity of the high-frequency electromagnetic field generated by the high-frequency antenna inside the vacuum container through the protective plate can be increased by making the protective plate thinner, thereby increasing the plasma density.

[0016] Preferably, the plasma processing apparatus of the present invention further includes: a current measuring unit that measures the current value of the high-frequency current introduced into the aforementioned high-frequency antenna. Thus, the user of the plasma processing apparatus can monitor the current value of the high-frequency current introduced into the metal fiber sheet, which helps to prevent the metal fiber sheet constituting the high-frequency antenna from melting due to excessive current flowing into the high-frequency antenna.

[0017] Preferably, the aforementioned current measuring unit further includes a current stopping control unit that stops the high-frequency current introduced into the aforementioned high-frequency antenna when the current value measured by the aforementioned current measuring unit exceeds a predetermined value. This reliably prevents the metal fiber sheet from melting. [Effects of the Invention]

[0018] According to the present invention, by using a high-frequency antenna made of metal fiber sheets, a large current can be efficiently passed through the high-frequency antenna even in the high frequency used to generate plasma.

Implementation Method

[0020] Using Figures 1 to 4, embodiments of the plasma processing apparatus and high-frequency antenna of the present invention will be described.

[0021] (1) Configuration of Plasma Processing Apparatus and High-Frequency Antenna of This Embodiment FIG1 is a schematic diagram showing the configuration of an embodiment of the present invention, namely, plasma processing apparatus 1. The plasma processing apparatus 1 is a film forming apparatus of plasma CVD method, and includes a plasma source 10, a vacuum container 21, a vacuum pump 22, a gas supply unit 23, a substrate holding unit 24, a substrate loading and unloading outlet 25, a high-frequency power supply 26, an impedance matching device 27, a current measuring unit 28, and a current stopping control unit 29.

[0022] First, the constituent elements of the plasma processing apparatus 1 other than the plasma source 10 will be described. The vacuum container 21 has a metal (e.g., stainless steel) wall 211, and plasma is generated in the internal space 212 of the vacuum container 21, which is formed inside the wall 211. The vacuum pump 22 is a pump that evacuates the internal space 212. The gas supply unit 23 consists of a gas storage tank (not shown) and a gas inlet pipe, and supplies plasma-generating gas such as argon or hydrogen, as well as film-forming material gas, to the internal space 212. Furthermore, in cases such as cleaning the substrate S formed by sputtering or plasma, or in cases where the substrate S is processed without using film-forming material gas, only plasma-generating gas is supplied to the internal space 212 from the gas supply unit 23. The substrate holding unit 24 holds the substrate S. The substrate inlet / outlet 25 is located in the wall portion 211 and is used for the substrate S to pass through when it is transferred from outside the vacuum container 21 to the substrate holding portion 24 before film formation, and when it is transferred from the substrate holding portion 24 to outside the vacuum container 21 after film formation. The substrate inlet / outlet 25 is sealed by the cover 251 except when the substrate S is being transferred in or out.

[0023] The high-frequency power supply 26 generates a high-frequency current with a frequency of 13.56 MHz and supplies the high-frequency current to the high-frequency antenna 11 described later. The impedance matching device 27 adjusts the impedance so that the high-frequency current from the high-frequency power supply 26 is efficiently introduced into the high-frequency antenna 11. The current measuring unit 28 is a galvanometer that measures the current value of the high-frequency current flowing to the power supply line 163 connected to the high-frequency antenna 11, and thereby measures the current value of the high-frequency current introduced into the high-frequency antenna 11. The current stop control unit 29 controls the high-frequency power supply 26 to stop the high-frequency current introduced into the high-frequency antenna 11 when the current value measured by the current measuring unit 28 exceeds a predetermined value.

[0024] In this embodiment, two plasma sources 10 are provided in one plasma processing apparatus 1. However, the number of plasma sources 10 is not limited to this; there may be only one or more. Each plasma source 10 has a high-frequency antenna 11, a protection plate 12, a strength reinforcing plate 13, an antenna fixing frame 14, an airtight retaining part 15, and two high-frequency current supply rods 16.

[0025] In this embodiment, a metal fiber sheet is used as the high-frequency antenna 11. The metal fiber sheet can be any sheet-like material composed of metal fibers. The sheet-like material composed of metal fibers can also be a nonwoven fabric with randomly arranged metal fibers, or a woven fabric or mesh fabric composed of metal fibers. Furthermore, the metal fiber sheet can also have a porous structure. Moreover, the metal fiber sheet can also contain constituent elements other than metal fibers. Preferably, at least a portion of the metal fibers constituting the metal fiber sheet are bonded together. The term "at least a portion of the metal fibers are bonded together" means that the metal fibers are physically fixed together. The metal fibers can also be directly fixed together, or they can be fixed by a component other than the metal component of the metal fibers (a second metal component). Among the various forms of metal fiber sheets described so far, a nonwoven fabric in which at least a portion of the metal fibers are bonded together is particularly preferred.

[0026] The high-frequency antenna 11, which is thus composed of a metal fiber sheet made of multiple metal fibers, has a larger surface area than a high-frequency antenna composed of a metal plate of the same shape as the metal fiber sheet, and therefore has a lower impedance to the high-frequency current. Therefore, the high-frequency current (e.g., 13.56 MHz) commonly used for plasma generation can be flowed more efficiently in the form of a large current.

[0027] Although the metal composition of the metal fiber and the second metal composition in the metal fiber sheet used in this embodiment are not particularly limited, copper is the primary metal used, and stainless steel, iron, copper, aluminum, bronze, brass, nickel, chromium, alloys of multiple metals, or any other metal can be used.

[0028] Although the average fiber diameter of the metal fibers in the metal fiber sheet used in this embodiment can be arbitrarily set, it is preferably 1 mm to 30 mm, and more preferably 2 mm to 20 mm. The "average fiber diameter" is the average area diameter derived by calculating the cross-sectional area of ​​the metal fibers based on a vertical cross-section of any part of the metal fiber sheet taken by a microscope (e.g., using known software), and then calculating the diameter of a circle with the same area as the aforementioned cross-sectional area (e.g., the average of 20 fibers). Furthermore, the average fiber length of the metal fibers in the metal fiber sheet used in this embodiment is preferably 1 mm to 10 mm, and more preferably 3 mm to 6 mm. The "average fiber length" is the value obtained by averaging multiple measurements (e.g., 20 samples) taken by a microscope. If the average fiber diameter and average fiber length of the metal fibers are within the ranges described above, it is easier to increase the surface area of ​​the metal fiber sheet and to reduce the impedance relative to high-frequency currents.

[0029] Preferably, the duty cycle of the metal fiber sheet used in this embodiment is 5-60% at a temperature of 25°C. If the duty cycle is too low, the surface area becomes smaller, and the high-frequency current flowing to the high-frequency antenna 11 also decreases. On the other hand, if the duty cycle is too high, the surface area becomes smaller because the portion of the metal fiber in contact with other metal fibers becomes larger, and the high-frequency current flowing to the high-frequency antenna 11 also decreases. The duty cycle can be measured based on the volume of the entire metal fiber sheet (including the perforated portion) at a temperature of 25°C and the volume of the metal fibers constituting the metal fiber sheet. The volume of the metal fiber sheet can be determined by measuring the thickness and area of ​​the metal fiber sheet using known methods.

[0030] Although the thickness of the metal fiber sheet is not particularly limited, it is preferably 100 mm to 1 mm. By setting the thickness of the metal fiber sheet within this range, it is easy to ensure the amount of high-frequency current that can flow to the high-frequency antenna. The thickness of the metal fiber sheet can be measured, for example, using a digital indicator ID-C112X manufactured by Mitutoyo Corporation.

[0031] The protective plate 12 is made of a dielectric material and is positioned to contact one of the surfaces of the high-frequency antenna 11. The strength reinforcing plate 13 is made of a dielectric material that is thicker than the protective plate 12 and is positioned to contact the surface of the high-frequency antenna 11 opposite to the aforementioned surface. Therefore, the high-frequency antenna 11 is sandwiched between the protective plate 12 and the strength reinforcing plate 13. In other words, a laminate 110 is formed by stacking the strength reinforcing plate 13, the high-frequency antenna 11, and the protective plate 12 in that order. The laminate 110 is configured such that one side of the protective plate 12 faces the opening 213 of the wall (upper wall) 211 of the vacuum container 21. The materials of the protective plate 12 and the strength reinforcing plate 13 can be alumina, zirconium dioxide, silicon nitride, aluminum nitride, etc. The protective plate 12 and the strength reinforcing plate 13 can also be made of the same material or different materials. In this embodiment, in order to facilitate the dissipation of heat generated from the high-frequency antenna 11 or plasma during use, aluminum nitride, which has high thermal conductivity in dielectric, is used in both the protection plate 12 and the strength reinforcement plate 13.

[0032] The antenna mounting frame 14 has a frame body portion 141 surrounding the sides of the high-frequency antenna 11, the protective plate 12, and the strength reinforcing plate 13, and a protrusion portion 142 protruding from the frame body portion 141 to the surface of the strength reinforcing plate 13 opposite to the high-frequency antenna 11 and covering a portion of that surface. If the strength reinforcing plate 13 side is set as the upper side, the antenna mounting frame 14 has an inverted L-shaped shape in a cross section perpendicular to the strength reinforcing plate 13. A hole is provided in the frame body portion 141 from top to bottom, and the antenna mounting frame 14 is fixed to the wall portion (upper wall) 211 of the vacuum container 21 located around the opening 213 by means of a bolt inserted through the hole. An airtight retaining portion 15 is provided on the upper part of the wall portion (upper wall) 211, which is further inside the frame body portion 141, and the laminate 110 is fixed to the protrusion portion 142 and the airtight retaining portion 15 in a state of being clamped from above and below. The airtight retaining part 15 has a sealing member (O-ring) 152 on the top of the frame member 151 and a sealing member (O-ring) 153 on the bottom. The upper sealing member 152 is pressed against the protective plate 12, and the lower sealing member 153 is pressed against the wall (upper wall) 211.

[0033] With this configuration, the high-frequency antenna 11 and the protective plate 12, as well as the high-frequency antenna 11 and the strength reinforcing plate 13, are tightly integrated into the laminate 110, and the laminate 110 functions as a cover to hermetically seal the opening 213. Since the high-frequency antenna 11 is separated from the internal space 212 of the vacuum container 21 by the protective plate 12, the protective plate 12 protects the high-frequency antenna 11 from the influence of plasma generated in the internal space 212.

[0034] In the strength reinforcing plate 13, there are two cubically shaped holes, each longer in one direction, arranged in a generally parallel manner. These holes accommodate high-frequency current supply rods 16 made of cubic metal rods. Metal power supply blocks 161, each disposed on the top of a high-frequency current supply rod 16, are fixed to the rod by bolts. The power supply blocks 161 are in integral contact with the top of the high-frequency current supply rod 16, extending from the top to the top of the strength reinforcing plate 13. Power supply terminals 162 are installed on each power supply block 161, and power supply lines 163 are connected to each power supply terminal 162. One power supply line 163 is connected to one terminal of the high-frequency power supply 26, and the other power supply line 163 is connected to the other terminal of the high-frequency power supply 26 via an impedance matching device 27. The length of each high-frequency current supply rod 16 is 30 mm, and the interval between two high-frequency current supply rods 16 is 150 mm.

[0035] To improve the high-frequency electromagnetic field generated in the internal space 212 of the vacuum container 21, the protective plate 12 is preferably thinner. On the other hand, since the laminate 110 is in contact with the internal space 212 of the vacuum container 21 on the protective plate 12 side and in contact with the atmosphere on the strength reinforcing plate 13 side, it is subjected to the force caused by the pressure difference between vacuum and atmospheric pressure. Therefore, in a way that can withstand this pressure difference, the strength reinforcing plate 13 is preferably thicker. However, if the strength reinforcing plate 13 is too thick, the heat generated in the high-frequency antenna 11 becomes difficult to dissipate. Furthermore, the necessary mechanical strength also depends on the size of the opening 213 of the vacuum container 21. It is preferable to consider the above points when determining the thickness of the protective plate 12 and the strength reinforcing plate 13. In this embodiment, the opening 213 is a rectangle with a long side of 210 mm and a short side of 160 mm, the thickness of the protective plate 12 is set to 3 mm, and the thickness of the strength reinforcing plate 13 is set to 20 mm. Of course, their thicknesses can be appropriately changed. For example, the thickness of the protective plate 12 can be set to a range of 1 to 5 mm, and the thickness of the strength reinforcing plate 13 can be set to a range of 5 to 30 mm. The thicknesses of the protective plate 12 and the strength reinforcing plate 13 can also be outside the ranges mentioned here.

[0036] (2) Operation of the Plasma Processing Apparatus of this Embodiment The operation of the plasma processing apparatus 1 of this embodiment will be described. First, the cover 251 of the substrate loading and unloading outlet 25 is opened, and the substrate S is loaded into the internal space 212 of the vacuum container 21. On this basis, the substrate S is held by placing it on the substrate holding part 24. Then, the cover 251 is closed, and the internal space 212 of the vacuum container 21 is evacuated by the vacuum pump 22. Then, the plasma generating gas and the film forming raw material gas are supplied to the internal space 212 from the gas supply part 23. Moreover, high-frequency current is introduced into the high-frequency antenna 11 from the high-frequency power supply 26 through the impedance matching device 27, the power supply line 163, the power supply terminal 162, the power supply block 161 and the high-frequency current supply rod 16. By introducing high-frequency current into the high-frequency antenna 11 in this way, a high-frequency electromagnetic field is generated in the internal space 212, and plasma is generated by ionizing the molecules of the plasma generating gas. Using this plasma, the molecules of the film-forming raw material gas are decomposed and deposited on the substrate S, thus achieving film formation.

[0037] If we observe the high-frequency antenna 11 as a whole, the high-frequency current, as indicated by the arrows in Figure 2, diffuses in a planar manner between the two high-frequency current supply rods 16 arranged in a generally parallel manner. If we focus on a part of the high-frequency antenna 11, the high-frequency current flows on the surface of each metal fiber constituting the high-frequency antenna 11.

[0038] In the plasma processing apparatus 1 of this embodiment, since the high-frequency antenna 11 is made of metal fiber sheets, the surface area of ​​the metal body (metal fiber) through which the high-frequency current flows is larger than that of a high-frequency antenna made of a metal plate having the same planar shape. Therefore, the high-frequency current can flow more efficiently in the form of a large current. As a result, the intensity of the high-frequency electromagnetic field introduced into the internal space 212 of the vacuum container 21 can be increased, and the density of the plasma generated in the internal space 212 can be increased.

[0039] The following shows the results of an experiment measuring the electron density of the plasma generated in the internal space 212 of the plasma processing apparatus 1 in this embodiment. In this experiment, the high-frequency antenna 11 was made of a metal fiber sheet with a 13% occupancy, formed by wet forming of copper fibers with an average fiber length of 3 mm and an average fiber diameter of 9 mm, dried, and then bonded together in an inert gas. As a comparative example, the same experiment was performed using a high-frequency antenna made of a conventional metal plate having the same planar shape as the high-frequency antenna 11. In both this embodiment and the comparative example, only one high-frequency antenna was used, and nitrogen gas was introduced into the internal space 212 of the vacuum container 21 at a pressure of 1.0 Pa and a flow rate of 100 sccm as the plasma generating gas. Based on this, high-frequency power was applied to the high-frequency antenna in the range of 100 to 1000 W, and the electron density of the plasma was measured using a Langmuir probe at a position 120 mm away from the antenna.

[0040] The experimental results are shown in Figure 3. In both the present embodiment and the comparative example, the electron density increases proportionally to the magnitude of the high-frequency power. When comparing the present embodiment and the comparative example with the same high-frequency power, it can be seen that the electron density of the present embodiment is about 15-20% higher than that of the comparative example across all the high-frequency power ranges measured. This is believed to be due to the fact that, in the present embodiment, the impedance of the high-frequency antenna 11 decreases due to the flow of high-frequency current on the surface of each metal fiber, thereby increasing the high-frequency current and thus increasing the intensity of the high-frequency electromagnetic field in the internal space 212 of the vacuum container 21.

[0041] As described above, the plasma processing apparatus 1 of this embodiment can achieve the following effects of the present invention: by using a high-frequency antenna 11 made of metal fiber sheets, the surface area through which the high-frequency current flows can be increased, thereby efficiently achieving the effect of passing a large current through the high-frequency antenna, and other effects described below can also be achieved.

[0042] In the plasma processing apparatus 1 of this embodiment, in addition to the high-frequency antenna 11 and the protective plate 12, a strength reinforcing plate 13 is also used. By integrating the high-frequency antenna 11 with the protective plate 12 and the high-frequency antenna 11 with the strength reinforcing plate 13, the mechanical strength of the cover that hermetically seals the opening 213 can be improved. Furthermore, since the strength of the protective plate 12 can be made weaker compared to the case without the strength reinforcing plate 13, the protective plate 12 can be made thinner (for example, thinner than the strength reinforcing plate 13). This increases the intensity of the high-frequency electromagnetic field generated by the high-frequency antenna 11 through the protective plate 12 within the internal space 212 of the vacuum container 21.

[0043] Generally, in cases where a planar high-frequency antenna is tightly sealed to a protective plate, the thermal expansion due to heating and the thermal contraction due to cooling are greater for a metal high-frequency antenna compared to a dielectric protective plate. This results in friction between the high-frequency antenna and the protective plate, causing wear on the high-frequency antenna and / or the protective plate. In contrast, in the plasma processing apparatus 1 of this embodiment, since the high-frequency antenna 11 is made of a metal fiber sheet, the metal fibers expand by narrowing the gaps between them when heated and contract by widening the gaps when cooled. Therefore, the overall thermal expansion / contraction of the high-frequency antenna 11 is smaller compared to that of a conventional metal plate high-frequency antenna. Consequently, the difference in thermal expansion / contraction between the metal fiber sheet high-frequency antenna 11 and the protective plate 12 is smaller than that of a conventional metal plate high-frequency antenna, reducing friction between the high-frequency antenna 11 and the protective plate 12. This suppresses wear on the high-frequency antenna 11 and / or the protective plate 12 caused by friction.

[0044] Furthermore, in the plasma processing apparatus 1 of this embodiment, the current value of the high-frequency current flowing through the high-frequency antenna 11 is measured by the current measuring unit 28. When the current value exceeds a predetermined value, the high-frequency power supply 26 is controlled by stopping the supply of high-frequency current to the high-frequency antenna 11 by the current stop control unit 29. This prevents the high-frequency antenna 11 from melting due to excessive current flowing to it.

[0045] (3)Modifications The present invention is not limited to the above-described embodiments and can be modified in various ways.

[0046] For example, in the plasma processing apparatus 1 of the present invention, instead of the plasma source 10 described above, the plasma source 10A shown in FIG4 can be used. This plasma source 10A includes a high-frequency antenna 11A, a protective plate 12, a first strength reinforcing plate 131A, a second strength reinforcing plate 132A, an antenna mounting frame 14, an airtight retaining portion 15, and two power supply blocks 161A. Since the configuration of the protective plate 12 and the airtight retaining portion 15 is the same as that in the above embodiment, description is omitted.

[0047] The first strength reinforcing plate 131A has a frame-like shape with a central cutout in the insulating material, and the second strength reinforcing plate 132A is housed within the frame. Although the high-frequency antenna 11A is made of the same metal fiber sheet as in the above embodiment, the mounting method to the plasma source 10A differs from that in the above embodiment. Specifically, the second strength reinforcing plate 132A is wound around a portion of the upper surface 1321 that contacts one side 1322 of the second strength reinforcing plate 132A, and then around the side 1322, the bottom surface 1323, the side 1324 opposite to the side 1322, and a portion of the upper surface 1325 that contacts the side 1324. Since the metal fiber sheet is flexible, the high-frequency antenna 11A can be wound around the second strength reinforcing plate 132A as described above.

[0048] Power supply blocks 161A are respectively mounted on regions 1321 and 1325. Each power supply block 161A is fixed to the second strength reinforcing plate 132A by a plurality of bolts. Thus, the high-frequency antenna 11A is pressed against the second strength reinforcing plate 132A by the power supply blocks 161A, thereby fixing the high-frequency antenna 11A to the second strength reinforcing plate 132A. Power supply terminals 162A are installed on each power supply block 161A, and power supply lines 163 are connected to each power supply terminal 162A. Similar to the embodiment described above, one power supply line 163 is connected to one terminal of the high-frequency power supply 26, and the other power supply line 163 is connected to the other terminal of the high-frequency power supply 26 via an impedance matching device 27.

[0049] Gaps are provided between the first strength reinforcing plate 131A and the high-frequency antenna 11A, and between the high-frequency antenna 11A and the protective plate, and these gaps are filled with an adhesive 135 composed of a dielectric and a resin, i.e., silicone resin grease. Because of the adhesive 135, the thermal contact between the first strength reinforcing plate 131A and the high-frequency antenna 11A, and between the high-frequency antenna 11A and the protective plate becomes good, so the heat generated by the high-frequency antenna 11A, or the heat generated with plasma generation, can be easily discharged to the outside of the plasma processing device.

[0050] The operation of the plasma source 10A and the plasma processing device having the plasma source 10A in this modified example is the same as the operation of the plasma source 10 and the plasma processing device 1 in the above embodiment.

[0051] The present invention can also be further modified. For example, although a strength reinforcing plate 13 is provided in the plasma processing apparatus 1 of the above embodiment, the strength reinforcing plate 13 may be omitted. In this case, a protective plate 12 with mechanical strength capable of withstanding the pressure difference between the inside and outside of the vacuum container is used.

[0052] Although the plasma processing apparatus 1 in the above embodiment uses a current measuring unit 28 and a current stopping control unit 29, it is also possible to provide only the current measuring unit 28 and omit the current stopping control unit 29. Since approximately the same current flows to the high-frequency antenna 11 when plasma processing is performed under the same conditions, when only the current measuring unit 28 is provided in the plasma processing apparatus, the current measuring unit 28 can be used in such a way that, during the preparatory experiment to determine the conditions for plasma processing, the user determines the conditions by observing the current value measured by the current measuring unit 28 while conducting the preparatory experiment (thereafter, it is not necessary to monitor the current value). Alternatively, both the current measuring unit 28 and the current stopping control unit 29 can be omitted. [Simplified Explanation of the Diagram]

[0019] [Fig. 1] Fig. 1(a) is a schematic configuration diagram showing an embodiment of the plasma processing apparatus of the present invention, and Fig. 1(b) is an enlarged view of the area near the high-frequency antenna. [Fig. 2] Fig. 2 is a diagram showing the flow of high-frequency current in the high-frequency antenna of the plasma processing apparatus of the present embodiment, indicated by arrows. [Fig. 3] Fig. 3 is a graph showing the electron density of plasma generated in the plasma processing apparatus of the present embodiment and in a plasma processing apparatus using an antenna made of a conventional metal plate. [Fig. 4] Fig. 4 is a schematic configuration diagram showing a modified example of the plasma source of the present invention.

Claims

1. A high-frequency antenna, characterized in that: it comprises a sheet made solely of metal fibers connected to a high-frequency power source; the duty cycle of the metal fibers in the sheet at a temperature of 25°C is 10-60%; the sheet has a porous structure, wherein the metal fibers expand by narrowing the gaps between them when heated, and contract by expanding the gaps when cooled, thereby reducing the thermal expansion or contraction of the high-frequency antenna as a whole compared to a high-frequency antenna made of a metal plate having the same planar shape; and the sheet is at least a portion of the metal fibers bonded together.

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