Plasma treatment device

Abstract

This invention maintains the vacuum in a vacuum container, even if a dielectric plate has broken. A plasma treatment device (101) is provided with: a vacuum container (1) having an evacuated interior; an antenna (3) that is provided to the exterior of the vacuum container and causes plasma to be generated in the interior of the vacuum container (1) due to the flow of a high-frequency current; a dielectric plate (5) for blocking off an opening (1a) formed at a location facing the antenna (3) in the vacuum container (1); and an insulating sheet member (6) covering the dielectric plate (5) from the outside of the vacuum container (1). A peripheral edge part of the sheet member (6) is fixed to the periphery of a region in the vacuum container (1) where the dielectric plate (5) is arranged.

Description

Plasma processing equipment

[0001] The present disclosure relates to a plasma processing apparatus.

[0002] A plasma processing apparatus using an inductively coupled plasma is known, in which a high-frequency electric field generated by an antenna disposed outside a vacuum chamber is introduced through a dielectric window provided in the vacuum chamber. For example, Patent Document 1 describes a plasma processing apparatus that has a dielectric window formed by including a slit plate that closes an opening formed in the vacuum chamber at a position facing the antenna, and a dielectric plate that closes a slit formed in the slit plate from outside the vacuum chamber.

[0003] Japanese Patent Application Publication No. 2021-111595

[0004] However, in the plasma processing apparatus disclosed in Patent Document 1, if the dielectric plate is damaged, the vacuum in the vacuum chamber cannot be maintained depending on the extent of the damage.

[0005] An aspect of the present disclosure aims to maintain the vacuum in the vacuum vessel even if the dielectric plate is damaged.

[0006] In order to solve the above problems, a plasma processing apparatus according to one embodiment of the present disclosure comprises a vacuum container whose interior is evacuated to a vacuum, an antenna provided outside the vacuum container and configured to generate plasma inside the vacuum container when a high-frequency current flows through it, a dielectric plate that covers an opening formed in the vacuum container facing the antenna, and an insulating sheet member that covers the dielectric plate from the outside of the vacuum container, the peripheral portion of the sheet member being fixed around the area of ​​the vacuum container where the dielectric plate is located.

[0007] According to one aspect of the present disclosure, the vacuum in the vacuum container can be maintained even if the dielectric plate is damaged.

[0008] Fig. 5 is a longitudinal sectional view showing the configuration of a plasma processing apparatus according to an embodiment of the present disclosure; Fig. 6 is a plan view showing the configuration of the plasma processing apparatus; Fig. 7 is a longitudinal sectional view showing the configuration of a main part of the plasma processing apparatus; Fig. 8 is a plan view showing an enlarged view of a part of a sheet member provided in the plasma processing apparatus; Fig. 9 is a longitudinal sectional view showing the configuration of a plasma processing apparatus according to a modified example; Fig. 10 is a longitudinal sectional view showing the configuration of a main part of the plasma processing apparatus shown in Fig. 5;

[0009] First Embodiment A first embodiment of the present disclosure will be described in detail below.

[0010] <Configuration of Plasma Processing Apparatus> Fig. 1 is a vertical cross-sectional view showing the configuration of a plasma processing apparatus 101 according to this embodiment. Fig. 2 is a plan view showing the configuration of the plasma processing apparatus 101. Fig. 3 is a vertical cross-sectional view showing the configuration of a main part of the plasma processing apparatus 101.

[0011] 1 to 3, the plasma processing apparatus 101 is an apparatus that performs processes such as carburizing, nitriding, ashing, etching, and film formation on a workpiece 20 by using an inductively coupled plasma P. A bias voltage is applied to the workpiece 20.

[0012] The plasma processing apparatus 101 includes a vacuum vessel 1, a vacuum exhaust device 2, an antenna 3 (plasma generating unit), a high-frequency power supply 4, a dielectric plate 5, a sheet member 6, a holding frame 7, and a plurality of bolts 8. The plasma processing apparatus 101 also includes a gasket 9 (first sealing member) and an O-ring 10 (second sealing member) as sealing members.

[0013] A vacuum vessel 1 is a vessel into which a plasma source gas G is introduced. The interior of the vacuum vessel 1 is evacuated by a vacuum exhaust device 2. The vacuum vessel 1 is made of, for example, metal and is electrically grounded.

[0014] A rectangular opening 1a is formed in the upper wall of the vacuum vessel 1, penetrating the upper wall in the thickness direction. The opening 1a is located facing an antenna 3, which will be described later. The opening 1a is surrounded by an opening edge 1b having a predetermined width in both the short and long side directions of the opening 1a. The opening edge 1b is located at a position lower than the outer surface of the upper wall of the vacuum vessel 1.

[0015] An exhaust pipe 1c is provided on the bottom wall of the vacuum vessel 1. The exhaust pipe 1c is a pipe that connects the inside of the vacuum vessel 1 with the vacuum exhaust device 2. A gate valve (not shown) is arranged between the vacuum exhaust device 2 and the exhaust pipe 1c. The gate valve has an adjustable opening. By adjusting the opening of the gate valve, the amount of exhaust by the vacuum exhaust device 2 is adjusted. By adjusting the amount of exhaust, the degree of vacuum inside the vacuum vessel 1 is adjusted.

[0016] A gas inlet 1d is provided on the side wall of the vacuum vessel 1 to introduce a gas G into the vacuum vessel 1. The gas G is oxygen (O ２ ) or nitrogen (N ２ ) is used.

[0017] The antenna 3 generates an induced electric field when a high-frequency current flows due to high-frequency power supplied from the high-frequency power source 4. This causes the antenna 3 to generate plasma inside the vacuum chamber 1. The antenna 3 has a linear main body and curved ends provided on both sides of the main body. The antenna 3 is disposed outside the vacuum chamber 1, close to the dielectric plate 5, with the main body facing the opening 1a. One end of the antenna 3, which serves as the power supply end, is connected to the high-frequency power source 4, and the other end, which serves as the termination end of the antenna 3, is grounded. The antenna 3 is formed from a material such as copper, aluminum, an alloy thereof, or stainless steel, but may be formed from other materials.

[0018] The number of antennas 3 is not limited to one, and may be multiple. When multiple antennas 3 are provided, they are arranged in parallel with each other at intervals.

[0019] The high frequency power supply 4 is a power supply that supplies high frequency power to the antenna 3. The frequency of the high frequency power is, for example, a general 13.56 MHz, but is not limited to this.

[0020] The dielectric plate 5 is disposed on the edge 1b of the opening 1a in a loose state so as to cover the opening 1a. The dielectric plate 5 is a plate-shaped member made entirely of a dielectric material, such as ceramics, inorganic material, or resin material.

[0021] The sheet member 6 is a sheet-like member that covers the dielectric plate 5 from the outside of the vacuum vessel 1 and has insulating properties. The sheet member 6 is formed from a polyimide film such as Kapton (registered trademark) or a resin such as Teflon (registered trademark). The material of the sheet member 6 preferably has a dielectric loss tangent of 0.01 or less, and more preferably has a dielectric loss tangent of 0.005 or less. By forming the sheet member 6 from a material with a dielectric loss tangent of 0.01 or less, excessive heat generation of the sheet member 6 can be suppressed.

[0022] A peripheral edge 6a of the sheet member 6 is fixed by bolts 8 around the periphery of the opening edge 1b, which is the area of ​​the vacuum vessel 1 where the dielectric plate 5 is placed, so as to press down on the dielectric plate 5. The sheet member 6 is also fixed to the vacuum vessel 1 by the bolts 8, thereby airtightly covering the dielectric plate 5. The sheet member 6 has bolt holes 6b for fixing with the bolts 8.

[0023] The holding frame 7 is a metal frame-like member with an opening 7a formed on the inside that is approximately the same size and shape as the outer peripheral edge of the opening edge 1b. The holding frame 7 is arranged around the opening edge 1b on the outer surface of the upper wall of the vacuum vessel 1 so that the opening 7a is approximately aligned with the opening 1a. The holding frame 7 is fixed to the vacuum vessel 1 with bolts 8, thereby pressing down on the peripheral edge 6a of the sheet member 6 from above.

[0024] The bolts 8 are arranged at intervals on the holding frame 7. The shafts 8a of the bolts 8 are inserted into through holes 7b provided in the holding frame 7 and bolt holes 6b in the sheet member 6. The bolts 8 are fastened to the upper wall of the vacuum vessel 1, thereby fixing the sheet member 6 and the holding frame 7 to the upper wall of the vacuum vessel 1.

[0025] The gasket 9 has a frame shape and is approximately the same size as the lower surface of the holding frame 7. The gasket 9 is disposed between the peripheral edge 6a of the sheet member 6 and the upper wall of the vacuum vessel 1. The gasket 9 seals the gap between the sheet member 6 and the vacuum vessel 1. To improve the sealing performance, two gaskets 9 may be stacked on top of each other with a spacer between them, or a thicker gasket 9 may be used.

[0026] The O-ring 10 is disposed between the lower surface of the peripheral edge of the dielectric plate 5 and the opening edge 1b of the vacuum vessel 1. The O-ring 10 seals the gap between the dielectric plate 5 and the vacuum vessel 1.

[0027] <Effects of Sheet Member> FIG. 4 is an enlarged plan view showing a part of the sheet member 6 provided in the plasma processing apparatus 101. As shown in FIG.

[0028] In the plasma processing apparatus 101 configured as described above, the dielectric plate 5 is covered with the sheet member 6. As a result, even if the dielectric plate 5 is damaged, such as cracked, the damaged area is also covered with the sheet member 6. Therefore, even if the dielectric plate 5 is damaged, the vacuum inside the vacuum chamber 1 can be maintained by the sheet member 6.

[0029] The sheet member 6 airtightly covers the dielectric plate 5. The sheet member 6 is held by the holding frame 7 by fastening bolts 8, and tension is applied to the sheet member 6, allowing it to airtightly cover the dielectric plate 5. As a result, when the dielectric plate 5 is damaged and air can pass through the damaged area, the sheet member 6 can adhere to the damaged area and seal it.

[0030] In addition, if the sheet member 6 covers the dielectric plate 5 relatively loosely while being held down by the holding frame 7 without fastening the bolts 8, if the dielectric plate 5 is damaged and air is able to pass through the damaged area, the sheet member 6 may have difficulty adhering to the damaged area. Therefore, it is preferable that the sheet member 6 airtightly covers the dielectric plate 5 by fastening the bolts 8. However, if the holding frame 7 applies an external pressure above a certain level to the sheet member 6, the sheet member 6 will adhere to the damaged area. Therefore, in such a case, it is not necessary to cover the dielectric plate 5 airtightly.

[0031] The sheet member 6 is fixed to the vacuum vessel 1 so as to press down on the dielectric plate 5. This allows the dielectric plate 5 to be held in the vacuum vessel 1 even when it is simply placed thereon without being fixed to the vacuum vessel 1. This ensures sealing at the peripheral edge 6a of the sheet member 6. It also ensures sufficient fixing strength for the dielectric plate 5. Furthermore, even if the internal pressure of the vacuum vessel 1 increases due to replacement of the gas G inside the vacuum vessel 1, causing the dielectric plate 5 to rise, this can be prevented. Therefore, it is possible to prevent the dielectric plate 5 from rising or becoming detached.

[0032] The peripheral edge 6a of the sheet member 6 is fixed to the vacuum vessel 1 by bolts 8. A gasket 9 seals the gap between the peripheral edge 6a of the sheet member 6 and the vacuum vessel 1. An O-ring 10 seals the gap between the dielectric plate 5 and the opening edge 1b of the vacuum vessel 1. This improves the sealing performance between the peripheral edge 6a of the sheet member 6 and the vacuum vessel 1. It also improves the sealing performance between the dielectric plate 5 and the opening edge 1b. It also helps to suppress an increase in pressure inside the vacuum vessel 1, which is likely to occur when the dielectric plate 5 is damaged.

[0033] The sheet member 6 is flat when the vacuum vessel 1 is evacuated by the vacuum exhaust device 2. However, the peripheral edge 6a of the sheet member 6 is displaced due to the expansion and contraction of the gasket 9 and the O-ring 10. For this reason, as shown in Fig. 4, the bolt hole 6b of the sheet member 6 is formed as an elongated hole that is long in the direction in which the peripheral edge 6a displaces relative to the shank 8a of the bolt 8 in response to the expansion and contraction of the gasket 9 and the O-ring 10. The bolt hole 6b is also formed to be longer (larger) than the range W of displacement of the peripheral edge 6a relative to the shank 8a in response to the expansion and contraction.

[0034] As a result, even if the peripheral edge 6 a of the sheet member 6 is displaced as a result of expansion and contraction of the gasket 9 and the O-ring 10, the peripheral edge 6 a can be displaced without being hindered by the bolt 8. Therefore, the sheet member 6 is less likely to be deformed or damaged due to the expansion and contraction of the gasket 9 and the O-ring 10.

[0035] Modifications Modifications of the present embodiment will be described below. For ease of explanation, components having the same functions as those described in the present embodiment will be denoted by the same reference numerals, and the description thereof will not be repeated.

[0036] 5 is a vertical cross-sectional view showing the configuration of a plasma processing apparatus 102 according to this modification, and FIG. 6 is a vertical cross-sectional view showing the configuration of a main part of the plasma processing apparatus 102.

[0037] 5 and 6, in the plasma processing apparatus 102, the opening 1a of the vacuum vessel 1 in the above-described plasma processing apparatus 101 is replaced with two openings 1e. The dielectric plate 5 in the plasma processing apparatus 102 is formed by joining two basic dielectric plates 5A together.

[0038] Furthermore, the plasma processing apparatus 102 is provided with two O-rings 11 instead of the O-ring 10 in the plasma processing apparatus 101. The O-rings 11 are arranged so as to be interposed between the lower surface of the peripheral edge of the basic dielectric plate 5A and the opening edge 1b of the vacuum vessel 1. The O-rings 11 provide a seal between the basic dielectric plate 5A and the vacuum vessel 1.

[0039] The number of openings 1e, basic dielectric plates 5A and O-rings 11 is not limited to two, but may be any number as long as they are plural.

[0040] In the plasma processing apparatus 102 configured as described above, the dielectric plate 5 is formed by joining basic dielectric plates 5A together, which allows the dielectric plate 5 to be formed large. Furthermore, if dielectric breakdown occurs at the joints of the basic dielectric plates 5A in the dielectric plate 5, the joints become creeping surfaces, making it easy for discharge (creeping discharge) to occur between the antenna 3 and the opening edge 1b via the creeping surfaces. In contrast, by covering the dielectric plate 5 formed from multiple basic dielectric plates 5A with a sheet member 6, the above-mentioned dielectric breakdown can be prevented. Furthermore, in the plasma processing apparatus 102, even if the dielectric plate 5 is damaged, the sheet member 6 can maintain the vacuum inside the vacuum chamber 1, just like the plasma processing apparatus 101.

[0041] [Summary] A plasma processing apparatus according to a first aspect of the present disclosure comprises a vacuum vessel whose interior is evacuated to a vacuum, an antenna provided outside the vacuum vessel and configured to generate plasma inside the vacuum vessel when a high-frequency current flows through it, a dielectric plate that covers an opening formed in the vacuum vessel facing the antenna, and an insulating sheet member that covers the dielectric plate from the outside of the vacuum vessel, the peripheral portion of the sheet member being fixed around the area of ​​the vacuum vessel where the dielectric plate is located.

[0042] In the above configuration, since the dielectric plate is covered with the sheet member, even if the dielectric plate is damaged, the damaged area is also covered with the sheet member, and therefore, even if the dielectric plate is damaged, the sheet member can maintain the vacuum in the vacuum vessel.

[0043] A plasma processing apparatus according to a second aspect of the present disclosure is the plasma processing apparatus of the first aspect, wherein the sheet member airtightly covers the dielectric plate.

[0044] According to the above configuration, when the dielectric plate is damaged and air can pass through the damaged area, the sheet member can adhere to and seal the damaged area.

[0045] A plasma processing apparatus according to a third aspect of the present disclosure is the plasma processing apparatus of the first aspect, wherein the sheet member is fixed to the vacuum chamber so as to press the dielectric plate.

[0046] In the above configuration, the sheet member presses the dielectric plate, thereby holding the dielectric plate without fixing it to the vacuum vessel. This ensures sealing at the peripheral edge of the sheet member and also ensures sufficient fixing strength for the dielectric plate. Furthermore, it is possible to prevent the dielectric plate from floating up when the internal pressure of the vacuum vessel increases.

[0047] A fourth aspect of the present disclosure provides the plasma processing apparatus of the first aspect, wherein the dielectric plate is formed by joining a plurality of base dielectric plates together.

[0048] In the above configuration, the dielectric plate can be formed large, and the sheet member can prevent dielectric breakdown that tends to occur at the joints between a plurality of base dielectric plates.

[0049] A plasma processing apparatus according to a fifth aspect of the present disclosure may be any of the first to fourth aspects, wherein the peripheral portion of the sheet member is fixed to the vacuum vessel with bolts, the dielectric plate is positioned on the opening edge portion around the opening in the vacuum vessel, and the plasma processing apparatus further comprises a first sealing member interposed between the peripheral portion of the sheet member and the vacuum vessel, and a second sealing member interposed between the dielectric plate and the opening edge portion.

[0050] According to the above configuration, it is possible to improve the sealing performance between the peripheral edge of the sheet member and the vacuum vessel, and between the dielectric plate and the opening edge, and also to suppress an increase in pressure inside the vacuum vessel when the dielectric plate is damaged.

[0051] A plasma processing apparatus according to a sixth aspect of the present disclosure may be any of the first to fourth aspects, wherein the peripheral portion of the sheet member has a bolt hole through which the shank of the bolt is inserted, and the bolt hole is formed larger than the range over which the peripheral portion displaces relative to the bolt in response to expansion and contraction of the first seal member and the second seal member.

[0052] According to the above configuration, when the peripheral edge of the seat member is displaced due to expansion and contraction of the first seal member and the second seal member, the peripheral edge can be displaced without being hindered by the bolt.

[0053] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. In addition, embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present disclosure.

[0054] REFERENCE SIGNS LIST 1 vacuum vessel 1a, 1e opening 3 antenna 4 high frequency power supply 5 dielectric plate 5A basic dielectric plate 6 sheet member 6a peripheral portion 6b bolt hole 8 bolt 8a shaft portion 9 gasket (first sealing member) 10, 11 O-ring (second sealing member) 101, 102 plasma processing apparatus

Claims

1. A plasma processing apparatus comprising: a vacuum vessel whose interior is evacuated; an antenna provided outside the vacuum vessel for generating plasma inside the vacuum vessel when a high-frequency current flows through it; a dielectric plate for covering an opening formed in the vacuum vessel at a position facing the antenna; and an insulating sheet member for covering the dielectric plate from the outside of the vacuum vessel, the peripheral portion of the sheet member being fixed around the area of ​​the vacuum vessel where the dielectric plate is located.

2. The plasma processing apparatus according to claim 1, wherein said sheet member covers said dielectric plate airtightly.

3. The plasma processing apparatus according to claim 1, wherein said sheet member is fixed to said vacuum vessel so as to press said dielectric plate.

4. The plasma processing apparatus according to claim 1, wherein said dielectric plate is formed by joining a plurality of basic dielectric plates together.

5. A plasma processing apparatus according to any one of claims 1 to 4, wherein the peripheral portion of the sheet member is fixed to the vacuum vessel by bolts, the dielectric plate is positioned on the opening edge portion around the opening in the vacuum vessel, and the plasma processing apparatus further comprises: a first sealing member interposed between the peripheral portion of the sheet member and the vacuum vessel; and a second sealing member interposed between the dielectric plate and the opening edge portion.

6. A plasma processing apparatus as described in claim 5, wherein the peripheral portion of the sheet member has a bolt hole through which the shank of the bolt is inserted, and the bolt hole is formed larger than the range of displacement of the peripheral portion relative to the bolt in response to expansion and contraction of the first seal member and the second seal member.

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