Plasma processing equipment

Abstract

To maintain vacuum in a vacuum vessel even if a dielectric plate is damaged.SOLUTION: A plasma processing apparatus (101) includes a vacuum vessel (1) whose interior is evacuated, an antenna (3) provided outside the vacuum vessel, for generating plasma inside the vacuum vessel (1) by flowing high-frequency current, a dielectric plate (5) that blocks an opening (1a) formed at a position facing the antenna (3) within the vacuum vessel (1), and an insulating sheet member (6) that covers the dielectric plate (5) from the outside of the vacuum vessel (1). The peripheral edge of the sheet member (6) is fixed around the area where the dielectric plate (5) is positioned within the vacuum vessel (1).SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] There is known a plasma processing apparatus using inductively coupled plasma 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 in which a dielectric window is constituted by including a slit plate that closes an opening formed at a position facing the antenna of the vacuum chamber and a dielectric plate that closes a slit formed in the slit plate from the outside of the vacuum chamber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

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

[0005] One aspect of the present disclosure aims to maintain the vacuum in the vacuum chamber even when the dielectric plate is damaged.

Means for Solving the Problems

[0006] To solve the above problems, a plasma processing apparatus according to one aspect of the present disclosure comprises a vacuum vessel whose interior is evacuated; an antenna provided outside the vacuum vessel which generates plasma inside the vacuum vessel by passing a high-frequency current through it; a dielectric plate that closes an opening formed in the vacuum vessel at a position facing the antenna; and an insulating sheet member that covers the dielectric plate from the outside of the vacuum vessel, wherein the peripheral edge of the sheet member is fixed around the region in the vacuum vessel where the dielectric plate is arranged. [Effects of the Invention]

[0007] According to one aspect of this disclosure, the vacuum in the vacuum chamber can be maintained even if the dielectric plate is damaged. [Brief explanation of the drawing]

[0008] [Figure 1] This is a longitudinal cross-sectional view showing the configuration of a plasma processing apparatus according to one embodiment of the present disclosure. [Figure 2] This is a plan view showing the configuration of the plasma processing apparatus described above. [Figure 3] This is a longitudinal cross-sectional view showing the configuration of the main parts of the plasma processing apparatus described above. [Figure 4] This is a plan view showing an enlarged portion of the sheet member provided in the plasma processing apparatus described above. [Figure 5] This is a longitudinal cross-sectional view showing the configuration of a plasma processing apparatus according to a modified example. [Figure 6] Figure 5 is a longitudinal cross-sectional view showing the configuration of the main parts of the plasma processing apparatus described above. [Modes for carrying out the invention]

[0009] [Embodiment 1] Embodiment 1 of this disclosure will be described in detail below.

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

[0011] As shown in Figures 1 to 3, the plasma processing apparatus 101 is a device that uses inductively coupled plasma P to perform carburizing, nitriding, ashing, etching, and film deposition processes on a workpiece 20. A bias voltage is applied to the workpiece 20.

[0012] The plasma processing apparatus 101 comprises a vacuum vessel 1, a vacuum evacuation device 2, an antenna 3 (plasma generation unit), a high-frequency power supply 4, a dielectric plate 5, a sheet member 6, a retaining 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] The vacuum vessel 1 is a container into which the plasma source gas G is introduced. The inside of the vacuum vessel 1 is evacuated by the vacuum evacuation 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 positioned facing the antenna 3, which will be described later. Around the opening 1a, opening edges 1b are provided, each having a predetermined width in the short and long directions of the opening 1a. The opening edges 1b are formed 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 portion of the vacuum container 1. The exhaust pipe 1c is a pipe that connects the inside of the vacuum container 1 and 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 is a valve whose opening degree can be adjusted. By adjusting the opening degree of the gate valve, the exhaust volume by the vacuum exhaust device 2 is adjusted. By adjusting the exhaust volume, the degree of vacuum inside the vacuum container 1 is adjusted.

[0016] A gas inlet 1d for introducing the gas G into the inside of the vacuum container 1 is provided on the side wall portion of the vacuum container 1. As the gas G, oxygen (O2) or nitrogen (N2) is used.

[0017] The antenna 3 generates an induced electric field when a high-frequency current flows due to the high-frequency power supplied from the high-frequency power supply 4. Thereby, the antenna 3 generates plasma inside the vacuum container 1. The antenna 3 has a linear main body portion and curved end portions provided on both sides of the main body portion. The antenna 3 is arranged outside the vacuum container 1 at a position close to the dielectric plate 5 such that the main body portion faces the opening 1a. A high-frequency power supply 4 is connected to one end portion that serves as the power supply end of the antenna 3, and the other end portion that serves as the terminal of the antenna 3 is grounded. The antenna 3 is formed of a material such as copper, aluminum, their alloys, stainless steel, etc., but may also be formed of other materials.

[0018] Note that the antenna 3 is not limited to one, and a plurality of antennas may be provided. When a plurality of antennas 3 are provided, they are arranged in parallel at intervals from each other.

[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 arranged in a state of not being fixed on the opening edge 1b so as to close the opening 1a. The dielectric plate 11b is a plate-shaped member entirely composed of a dielectric material, and is formed of ceramics, inorganic materials, resin materials, etc.

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

[0022] The peripheral edge 6a of the sheet member 6 is fixed around the opening edge 1b in the region where the dielectric plate 5 is arranged in the vacuum vessel 1 by bolts 8 so as to press the dielectric plate 5. Also, the sheet member 6 is fixed to the vacuum vessel 1 by bolts 8, thereby covering the dielectric plate 5 airtightly. The sheet member 6 has bolt holes 6b for fixing by bolts 8.

[0023] The holding frame 7 is a metal frame-shaped member in which an opening 7a having substantially the same size and the same shape as the outer peripheral end of the opening edge 1b is formed inside. The holding frame 7 is arranged around the opening edge 1b on the outer surface of the upper wall portion of the vacuum vessel 1 so that the opening 7a substantially coincides with the opening 1a. The holding frame 7 is fixed to the vacuum vessel 1 by bolts 8, thereby holding the peripheral edge 6a of the sheet member 6 so as to press it from above.

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

[0025] The gasket 9 is frame-shaped and approximately the same size as the lower surface of the retaining frame 7. The gasket 9 is positioned between the peripheral edge 6a of the sheet member 6 and the upper wall of the vacuum container 1. The gasket 9 seals the space between the sheet member 6 and the vacuum container 1. To improve sealing performance, two gaskets 9 may be stacked with a spacer in between, or a thicker gasket 9 may be used.

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

[0027] <Effects of sheet material> Figure 4 is a plan view showing an enlarged portion of the sheet member 6 provided in the plasma processing apparatus 101.

[0028] In the plasma processing apparatus 101 configured as described above, the dielectric plate 5 is covered by a sheet member 6. As a result, even if damage such as cracks occurs in the dielectric plate 5, the damaged area is also covered by 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 in place by the retaining frame 7 by fastening bolts 8, which applies tension and allows 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 seal the damaged area by suction.

[0030] Furthermore, if the sheet member 6 is held in place by the retaining frame 7 without fastening the bolts 8 and covers the dielectric plate 5 relatively loosely, if the dielectric plate 5 is damaged and air can pass through the damaged area, the sheet member 6 may not adhere well to the damaged area. Therefore, it is preferable for the sheet member 6 to cover the dielectric plate 5 airtightly by fastening the bolts 8. However, if the retaining 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 cases, it is not always necessary to cover the dielectric plate 5 airtightly.

[0031] The sheet member 6 is fixed to the vacuum vessel 1 so as to hold down the dielectric plate 5. This allows the dielectric plate 5 to be held in place by the vacuum vessel 1 even if it is simply placed in the vacuum vessel 1 without being fixed to it. This ensures a seal at the peripheral edge 6a of the sheet member 6. It also ensures sufficient fixing strength for the dielectric plate 5. Moreover, even if the internal pressure of the vacuum vessel 1 increases due to gas G replacement or other reasons, and the dielectric plate 5 tries to float up, this can be prevented. Therefore, it is possible to prevent the dielectric plate 5 from floating up or coming loose.

[0032] The peripheral edge 6a of the sheet member 6 is fixed to the vacuum container 1 by bolts 8. The space between the peripheral edge 6a of the sheet member 6 and the vacuum container 1 is sealed by a gasket 9. The space between the dielectric plate 5 and the opening edge 1b of the vacuum container 1 is sealed by an O-ring 10. This improves the sealing performance between the peripheral edge 6a of the sheet member 6 and the vacuum container 1. It also improves the sealing performance between the dielectric plate 5 and the opening edge 1b. Furthermore, it suppresses the increase in pressure inside the vacuum container 1 that is likely to occur when the dielectric plate 5 is damaged.

[0033] Incidentally, the sheet member 6 becomes flat when the vacuum container 1 is being evacuated by the vacuum exhaust device 2. However, the peripheral portion 6a of the sheet member 6 is displaced due to the expansion and contraction of the gasket 9 and O-ring 10. For this reason, as shown in Figure 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 portion 6a is displaced relative to the shaft portion 8a of the bolt 8 in accordance with the expansion and contraction of the gasket 9 and O-ring 10. Furthermore, the bolt hole 6b is formed to be longer (larger) than the range W in which the peripheral portion 6a is displaced relative to the shaft portion 8a in accordance with the above-mentioned expansion and contraction.

[0034] As a result, even if the peripheral edge 6a of the seat member 6 is displaced due to expansion and contraction of the gasket 9 and O-ring 10, the peripheral edge 6a can be displaced without being obstructed by the bolt 8. Therefore, deformation and damage to the seat member 6 due to the expansion and contraction of the gasket 9 and O-ring 10 can be made less likely.

[0035] <Variations> Modifications of this embodiment are described below. For the sake of clarity, components having the same function as those described in this embodiment are denoted by the same reference numerals, and their descriptions are not repeated.

[0036] Figure 5 is a longitudinal cross-sectional view showing the configuration of the plasma processing apparatus 102 according to this modified example. Figure 6 is a longitudinal cross-sectional view showing the configuration of the main part of the plasma processing apparatus 102.

[0037] As shown in Figures 5 and 6, in the plasma processing apparatus 102, the opening 1a of the vacuum vessel 1 in the plasma processing apparatus 101 described above 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 equipped with two O-rings 11 instead of the O-ring 10 in the plasma processing apparatus 101. The O-rings 11 are positioned 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 seal the space between the basic dielectric plate 5A and the vacuum vessel 1.

[0039] Note that the opening 1e, the basic dielectric plate 5A, and the O-ring 11 are not limited to two; there may be multiple of each.

[0040] In the plasma processing apparatus 102 configured as described above, the dielectric plate 5 can be made larger by joining together basic dielectric plates 5A. Furthermore, if dielectric breakdown occurs at the joint of the basic dielectric plates 5A in the dielectric plate 5, the joint becomes a creepage surface, making it easier for discharge (creepage discharge) to occur between the antenna 3 and the opening edge 1b via the creepage surface. 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. Also, in the plasma processing apparatus 102, even if the dielectric plate 5 is damaged, the vacuum inside the vacuum container 1 can be maintained by the sheet member 6, just as in 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 which generates plasma inside the vacuum vessel by passing a high-frequency current through it, a dielectric plate that closes an opening formed in the vacuum vessel at a position facing the antenna, and an insulating sheet member that covers the dielectric plate from the outside of the vacuum vessel, wherein the peripheral edge of the sheet member is fixed around the region in the vacuum vessel where the dielectric plate is arranged.

[0042] In the above configuration, since the dielectric plate is covered by the sheet member, even if the dielectric plate is damaged, the damaged area is also covered by the sheet member. Therefore, even if the dielectric plate is damaged, the vacuum in the vacuum chamber can be maintained by the sheet member.

[0043] In the plasma processing apparatus according to a second aspect of the present disclosure, in the first aspect, the sheet member may hermetically cover the dielectric plate.

[0044] With the above configuration, when the dielectric plate is damaged and air can pass through the damaged area, the sheet member can seal the damaged area by suction.

[0045] In the plasma processing apparatus according to a third aspect of the present disclosure, in the first aspect, the sheet member may be fixed to the vacuum vessel so as to hold down the dielectric plate.

[0046] In the above configuration, the sheet member holds the dielectric plate in place, thus preventing the dielectric plate from being fixed to the vacuum vessel. Therefore, it is possible to ensure sealing performance at the periphery of the sheet member while also ensuring 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] In the fourth aspect of the present disclosure, the plasma processing apparatus may, in the first aspect, be formed by joining together a plurality of basic dielectric plates.

[0048] In the above configuration, a large dielectric plate can be formed. Furthermore, dielectric breakdown, which is likely to occur at the points where multiple basic dielectric plates are joined together, can be prevented by the sheet member.

[0049] A plasma processing apparatus according to a fifth aspect of the present disclosure may further include, in any of the first to fourth aspects, a periphery of the sheet member fixed to the vacuum vessel by bolts, a dielectric plate positioned on the opening edge surrounding the opening in the vacuum vessel, and the plasma processing apparatus further comprising a first sealing member interposed between the periphery of the sheet member and the vacuum vessel, and a second sealing member interposed between the dielectric plate and the opening edge.

[0050] According to the above configuration, the sealing performance between the peripheral edge of the sheet member and the vacuum vessel, and between the dielectric plate and the opening edge can be improved. In addition, the increase in pressure inside the vacuum vessel when the dielectric plate is damaged can be suppressed.

[0051] In any of the first to fourth embodiments, the plasma processing apparatus according to the sixth aspect of this disclosure has a bolt hole through which the shaft of the bolt is inserted at the peripheral edge of the sheet member. The bolt hole may be formed to be larger than the range in which the peripheral edge is displaced relative to the bolt in accordance with the expansion and contraction of the first and second sealing members.

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

[0053] [Additional Notes] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in each embodiment are also included within the technical scope of this disclosure. [Explanation of Symbols]

[0054] 1 Vacuum container 1a,1e opening 3 Antennas 4 High frequency power supply 5 Dielectric Plate 5A basic dielectric board 6 Sheet members 6a Peripheral area 6b Bolt hole 8 volts 8a Shaft 9. Gasket (first sealing member) 10,11 O-ring (second sealing member) 101,102 Plasma processing equipment

Claims

1. A vacuum vessel whose interior is evacuated, An antenna provided on the outside of the vacuum vessel, which generates plasma inside the vacuum vessel when a high-frequency current flows through it, A dielectric plate that closes an opening formed in the upper wall portion of the vacuum container at a position facing the antenna, so as to penetrate the upper wall portion in the thickness direction, The dielectric plate is covered by an insulating sheet member that covers the outside of the vacuum container, The dielectric plate is placed on the opening edge formed at a position lower than the outer surface of the upper wall portion around the opening. The peripheral edge of the sheet member is fixed to the outer surface of the upper wall of the vacuum vessel in a region higher than the opening edge surrounding the opening edge.

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

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

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

5. The peripheral edge of the sheet member is fixed to the vacuum container by bolts. The dielectric plate is placed on the opening edge surrounding the opening in the vacuum container, The aforementioned plasma processing apparatus is A first sealing member interposed between the peripheral edge of the sheet member and the vacuum container, The plasma processing apparatus according to any one of claims 1 to 4, further comprising a second sealing member interposed between the dielectric plate and the opening edge.

6. The peripheral edge of the sheet member has a bolt hole through which the shaft of the bolt is inserted. The plasma processing apparatus according to claim 5, wherein the bolt hole is formed to be larger than the range in which the peripheral portion is displaced relative to the bolt in accordance with the expansion and contraction of the first sealing member and the second sealing member.

Images