Plasma device

Abstract

This disclosure provides a plasma device, relating to the field of semiconductor equipment technology. The plasma device includes: a dielectric cylinder; a first end cap, disposed on the upper part of the dielectric cylinder, forming a plasma generation space with the dielectric cylinder; a coil, sleeved outside the dielectric cylinder, used to excite process gas entering the plasma generation space to generate plasma; and a cavity located below the dielectric cylinder, having a workpiece processing space for processing workpieces; wherein, sealing rings are respectively provided between the dielectric cylinder, the first end cap, and the cavity; along the radial direction of the dielectric cylinder, the wall thickness of the dielectric cylinder is 2 to 4 times the wall thickness of the sealing rings; a first groove is provided on the end face of the dielectric cylinder, a portion of the sealing rings is accommodated in the first groove, the surface area of ​​the first groove being less than or equal to half the surface area of ​​the sealing rings; the first end cap and the cavity are respectively provided with second grooves, a portion of the sealing rings is accommodated in the second grooves.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of semiconductor equipment, and in particular, to a plasma equipment. BACKGROUND

[0002] The plasma equipment is an important process equipment in semiconductor processes such as etching and desmear. The plasma equipment is usually configured with a plasma generation space and a workpiece processing space. The plasma generated in the plasma generation space can reach the surface of the workpiece in the workpiece processing space for processing. In the related art, since the distance between the workpiece and the plasma generation space is far, a large power is usually used to excite the process gas in the plasma generation space to generate plasma, so as to ensure that the concentration of the plasma reaching the surface of the workpiece meets the process requirement. However, this easily leads to sealing failure. SUMMARY

[0003] The present disclosure provides a plasma equipment.

[0004] As an aspect of the present disclosure, the present disclosure provides a plasma equipment, comprising: a dielectric cylinder; a first end cover, covering the upper part of the dielectric cylinder, and surrounding the dielectric cylinder to form a plasma generation space; a coil, sleeved outside the dielectric cylinder, for exciting the process gas in the plasma generation space to generate plasma; a cavity, located below the dielectric cylinder, and having a workpiece processing space for processing a workpiece; wherein, the dielectric cylinder, the first end cover and the cavity are respectively provided with a sealing ring; along the radial direction of the dielectric cylinder, the wall thickness of the dielectric cylinder is 2 to 4 times the wall thickness of the sealing ring; the end surface of the dielectric cylinder is provided with a first groove, part of the sealing ring is accommodated in the first groove, and the surface area of the first groove is less than or equal to half of the surface area of the sealing ring; the first end cover and the cavity are respectively provided with a second groove, part of the sealing ring is accommodated in the second groove.

[0005] In an embodiment, along the radial direction of the dielectric cylinder, the wall thickness of the dielectric cylinder is 3 times the wall thickness of the sealing ring.

[0006] In an embodiment, along the axial direction of the dielectric cylinder, the depth of the first groove is less than one third of the height of the sealing ring.

[0007] In an embodiment, along the axial direction of the dielectric cylinder, the ratio of the depth of the first groove to the height of the sealing ring is greater than or equal to 0.16 and less than or equal to 0.24.

[0008] In an embodiment, along the axial direction of the dielectric cylinder, the depth of the second groove is greater than half of the height of the sealing ring.

[0009] In an embodiment, the second groove has a depth of two-thirds of a height of the sealing ring along an axial direction of the medium cylinder.

[0010] In an embodiment, the first groove has a semicircular cross section parallel to an axial direction of the medium cylinder.

[0011] In an embodiment, the second groove has a dovetail cross section parallel to an axial direction of the medium cylinder, wherein a distance between opposite side walls of the second groove gradually decreases in a direction towards the medium cylinder.

[0012] In an embodiment, end faces of the medium cylinder are respectively provided with a gasket to separate the medium cylinder from the first end cover and the cavity by the gasket; the gasket is separated from the corresponding sealing ring and located outside the corresponding sealing ring.

[0013] In an embodiment, an upper portion of the cavity is provided with a first protective ring extending upwards, the first protective ring is located inside the medium cylinder; an outer diameter of the first protective ring is matched with an inner diameter of the medium cylinder.

[0014] In an embodiment, the first end cover is provided with a boss extending downwards, an outer diameter of the boss is matched with an inner diameter of the medium cylinder.

[0015] The plasma device provided by the embodiment reduces the temperature rise of the medium cylinder with a large wall thickness, and reduces the heat output from the heat source; by setting the surface area of the first groove to be less than or equal to half of the surface area of the sealing ring, the contact area of the sealing ring and the medium cylinder can be reduced, and the heat conduction from the medium cylinder to the sealing ring can be reduced, thereby effectively improving the problems of softening, loss of elasticity, and even melting of the sealing ring due to overheating.

[0016] The above summary is intended to illustrate only and is not intended to limit in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features will be readily apparent to those skilled in the art by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0017] In the drawings, like reference numerals refer to same or similar functionalities throughout the several views of the drawings. The drawings are not necessarily to scale. It is to be understood that the drawings only depict several embodiments of the disclosure and are not to be considered as limiting its scope.

[0018] Figure 1 A structural schematic diagram of a plasma device according to an embodiment of the disclosure is shown; Figure 2 A partial structure schematic diagram of a plasma device according to an embodiment of the present disclosure is shown.

[0019] Legend of reference signs: 10 - first end cover; 11 - second groove; 12 - third groove; 13 - boss; 20 - dielectric cylinder; 21 - plasma generation space; 22 - first groove; 30 - coil; 40 - cavity; 41 - workpiece processing space; 42 - second end cover; 421 - first guard ring; 43 - box; 50 - sealing ring; 60 - gasket; 70 - grid. DETAILED DESCRIPTION

[0020] Hereinafter, only certain exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present disclosure. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.

[0021] In the related art, a sealing ring is provided at the outer periphery of the dielectric cylinder to prevent gas in the plasma generation space from leaking. However, in a scenario where a larger power is used to excite the process gas in the plasma generation space to generate plasma, the temperature of the dielectric cylinder is high, the contact area between the dielectric cylinder and the sealing ring is usually large, and the temperature of the dielectric cylinder is extremely likely to cause the sealing ring to melt, resulting in sealing failure.

[0022] The present embodiment provides a plasma device, by increasing the thickness of the dielectric cylinder, reducing the temperature rise of the dielectric cylinder, and by reducing the contact area between the sealing ring and the dielectric cylinder, thereby reducing the heat conducted by the dielectric cylinder to the sealing ring, improving the melting phenomenon of the sealing ring, and prolonging the service life of the sealing ring.

[0023] The structure, function and implementation process of the plasma device provided by the present embodiment will be illustrated below in conjunction with the drawings.

[0024] As shown in Figure 1 and Figure 2 The plasma device provided by the present embodiment includes a dielectric cylinder 20, a first end cover 10 covering the upper part of the dielectric cylinder 20 and surrounding the dielectric cylinder 20 to form a plasma generation space 21, a coil 30 sleeved outside the dielectric cylinder 20 for exciting the process gas entering the plasma generation space 21 to generate plasma, and a cavity 40 located below the dielectric cylinder 20 and having a workpiece processing space 41 for processing workpieces.

[0025] The sealing ring 50 is arranged between the medium cylinder 20 and the first end cover 10 and the cavity 40 respectively. The wall thickness of the medium cylinder 20 is 2 to 4 times the wall thickness of the sealing ring 50 in the radial direction of the medium cylinder 20. The end surface of the medium cylinder 20 is provided with a first groove 22, and part of the sealing ring 50 is accommodated in the first groove 22. The surface area of the first groove 22 is less than or equal to half the surface area of the sealing ring 50. The first end cover 10 and the cavity 40 are respectively provided with a second groove 11, and part of the sealing ring 50 is accommodated in the second groove 11.

[0026] The medium cylinder 20 is usually made of a material with excellent dielectric properties and high temperature stability, such as high-purity quartz or alumina ceramic. These materials can efficiently couple radio frequency energy while withstanding the high temperature generated by the plasma. The medium cylinder 20 is usually cylindrical in shape.

[0027] The upper end cover of the medium cylinder 20 is provided with a first end cover 10, and the shape of the first end cover 10 can be adapted to the shape of the medium cylinder 20. For example, the first end cover 10 can be circular. The first end cover 10 and the medium cylinder 20 together enclose a circular plasma generation space 21, in which the process gas is excited to generate plasma. The material of the first end cover 10 can be selected according to actual needs. For example, the first end cover 10 can be made of a metal material, such as a surface-treated aluminum alloy plate or a stainless steel plate, to provide structural strength and better heat dissipation capability.

[0028] The first end cover 10 can be configured with an air-cooled channel or a liquid-cooled channel to reduce the temperature of the first end cover 10.

[0029] The coil 30 is sleeved outside the medium cylinder 20 and is usually wound into a spiral structure by a conductive material such as copper or copper alloy. The coil 30 is connected to an external radio frequency power source, and when current is passed, an alternating electromagnetic field is generated to excite the process gas entering the plasma generation space 21 to ionize and generate plasma.

[0030] A Faraday cage can be arranged between the coil 30 and the medium cylinder 20. The Faraday cage is made of a conductive material such as stainless steel or aluminum, which is a cylindrical cover with multiple axial gaps extending in the axial direction. These axial gaps are uniformly distributed in the circumferential direction of the medium cylinder 20. The main function of the Faraday cage is to shield electromagnetic interference.

[0031] A cavity 40 can be arranged below the medium cylinder 20, and the internal space of the cavity 40 serves as a workpiece processing space 41. A grid 70 can be arranged at the connection between the plasma generation space and the workpiece processing space 41. A carrying device can be arranged in the cavity 40, which is used to support the workpiece. For example, the carrying device can include a tray, or the carrying device can include an air floating structure.

[0032] The cavity 40 can include a box 43 and a second end cover 42 arranged at the upper end of the box 43. The material of the second end cover 42 and the box 43 can be selected according to actual needs. For example, the second end cover 42 can be made of a metal material, such as an aluminum alloy plate or a stainless steel plate, which has been surface treated to provide structural strength and better heat dissipation capability. The second end cover 42 can be provided with an air cooling channel or a liquid cooling channel to reduce the temperature of the second end cover 42.

[0033] A sealing ring 50 can be arranged between the upper end of the medium cylinder 20 and the first end cover 10. A sealing ring 50 can also be arranged between the lower end of the medium cylinder 20 and the second end cover 42. The sealing ring 50 has elasticity and heat resistance, for example, made of fluororubber or perfluoroether rubber.

[0034] In the radial direction (left-right direction in the figure) of the medium cylinder 20, the medium cylinder 20 has a large wall thickness to increase the heat capacity and thermal resistance of the medium cylinder 20 itself, which can effectively delay the temperature rise of the medium cylinder 20 and reduce the temperature of the wall of the medium cylinder 20. Specifically, the wall thickness of the medium cylinder 20 is 2 to 4 times the wall thickness of the sealing ring 50. For example, the wall thickness of the medium cylinder 20 is 2 times, 2.5 times, 3 times, 3.5 times, or 4 times the wall thickness of the sealing ring 50, or any multiple between any two of the above.

[0035] At least one first groove 22 is arranged at the upper end and the lower end of the medium cylinder 20. Correspondingly, a second groove 11 is arranged at the lower end of the first end cover 10 and at the upper end of the cavity 40. After assembly, the upper sealing ring 50 is arranged in the first groove 22 at the upper end of the medium cylinder 20 and the second groove 11 of the first end cover 10; the lower sealing ring 50 is arranged in the first groove 22 at the lower end of the medium cylinder 20 and the second groove 11 of the cavity 40.

[0036] The surface area of the first groove 22 is controlled to be less than or equal to half of the total surface area of the sealing ring 50. In this way, only half or less of the area of the sealing ring 50 is in direct contact with the medium cylinder 20, and more than half of the area is in contact with the second groove 11 of the first end cover 10 or the cavity 40, which has a relatively low temperature, thereby reducing the heat conducted from the medium cylinder 20 to the sealing ring 50. In the axial direction of the medium cylinder 20, the depth of the first groove 22 can be less than or equal to half of the size of the sealing ring 50.

[0037] The plasma device provided by the embodiment reduces the temperature rise of the medium cylinder 20 with a large wall thickness, and reduces the heat output from the heat source. By setting the surface area of the first groove 22 to be less than or equal to half of the surface area of the sealing ring 50, the contact area between the sealing ring 50 and the medium cylinder 20 can be reduced, and the heat conducted from the medium cylinder 20 to the sealing ring 50 can be reduced. The two work together to greatly reduce the temperature of the sealing ring 50 during operation, thereby effectively improving the problems of softening, loss of elasticity, and even melting of the sealing ring 50 due to overheating, greatly prolonging the service life and maintenance period of the sealing ring 50, and improving the sealing reliability of the plasma generation space 21 during operation of the device.

[0038] In some embodiments, along the radial direction of the medium cylinder 20, the wall thickness of the medium cylinder 20 is 3 times the wall thickness of the sealing ring 50. On the one hand, while ensuring that the thermal resistance meets the requirements, the medium cylinder 20 is also given a higher mechanical strength, which can better resist the risk of deformation caused by thermal stress due to temperature gradient and vacuum pressure difference; on the other hand, it is also beneficial to reduce the self-weight of the medium cylinder 20 and reduce the material cost.

[0039] In some examples, the ratio of the inner diameter to the outer diameter of the medium cylinder 20 is greater than or equal to 0.64 and less than or equal to 0.80. It can be understood that, in the case that the cross-sectional area of the plasma generation space 21 is unchanged, the smaller the ratio of the inner diameter to the outer diameter of the medium cylinder 20, the greater the wall thickness of the medium cylinder 20, and the greater the thermal resistance of the medium cylinder 20, which is more conducive to reducing the temperature of the wall of the medium cylinder 20.

[0040] In some embodiments, along the axial direction of the medium cylinder 20, the depth of the first groove 22 is less than one third of the height of the sealing ring 50. The first groove 22 is an annular groove. The height of the sealing ring 50 refers to the axial dimension of the sealing ring 50 in a free and uncompressed state.

[0041] The shallow first groove 22 makes the surface area of the first groove 22 small, and makes the contact area between the first groove 22 and the sealing ring 50 small, thereby reducing the heat conducted from the medium cylinder 20 to the sealing ring 50.

[0042] In some examples, along the axial direction of the medium cylinder 20, the ratio of the depth of the first groove 22 to the height of the sealing ring 50 is greater than or equal to 0.16 and less than or equal to 0.24.

[0043] Through the above setting, the depth of the first groove 22 can effectively accommodate and position the sealing ring 50, prevent the sealing ring 50 from slipping or falling off in the installation process or vibration scenarios, and make the contact area between the first groove 22 and the sealing ring 50 small, thereby reducing heat conducted from the medium cylinder 20 to the sealing ring 50.

[0044] In some embodiments, the depth of the second groove 11 is greater than half of the height of the sealing ring 50 along the axial direction of the medium cylinder 20.

[0045] The deeper second groove 11 forms a larger contact interface between the sealing ring 50 and the first end cover 10 and the cavity 40, which has good heat capacity and usually has a cooling circuit, to provide a dissipation path for the heat conducted from the sealing ring 50, thereby reducing the temperature of the sealing ring 50.

[0046] In some examples, the depth of the second groove 11 is two-thirds of the height of the sealing ring 50 along the axial direction of the medium cylinder 20. In this way, most of the sealing ring 50 is located in the second groove 11, so that the sealing ring 50 has a larger heat exchange area with the second groove 11, thereby efficiently dissipating the heat conducted from the sealing ring 50.

[0047] Optionally, the sum of the depth of the first groove 22 and the depth of the second groove 11 is less than the height of the sealing ring 50 to ensure the sealing effect of the sealing ring 50.

[0048] In some embodiments, the cross section of the first groove 22 is semicircular, wherein the cross section is parallel to the axial direction of the medium cylinder 20.

[0049] In this way, the side wall and the bottom of the first groove 22 are continuous and smooth circular arc surfaces. With the same depth, the surface area of the first groove 22 is smaller, which helps to ensure that the contact area between the first groove 22 and the sealing ring 50 is smaller. Moreover, the radius of curvature of the first groove 22 can be adapted to the sealing ring 50, thereby improving the positioning effect of the sealing ring 50.

[0050] In some embodiments, the cross section of the second groove 11 is dovetail-shaped, wherein the cross section is parallel to the axial direction of the medium cylinder 20. In this way, the distance between the opposite side walls of the second groove 11 gradually decreases in the direction towards the medium cylinder 20.

[0051] For the second groove 11 on the first end cover 10, the second groove 11 is wide at the top and narrow at the bottom. For the second groove 11 on the cavity 40, the second groove 11 is narrow at the top and wide at the bottom.

[0052] In this way, the second groove 11 can provide axial and radial constraints to the sealing ring 50, especially when the system pressure fluctuates or there is vibration, to prevent the sealing ring 50 from being extruded or even detached from the second groove 11. Moreover, the second groove 11 can have a larger surface area, so that the sealing ring 50 has a larger heat exchange area with the second groove 1 1, thereby improving the heat dissipation effect of the sealing ring 50.

[0053] In some embodiments, the end face of the medium cylinder 20 is provided with a gasket 60, so as to separate the medium cylinder 20 from the first end cover 10 and the cavity 40 by the gasket 60. The gasket 60 can be made of PTFE (polytetrafluoroethylene).

[0054] Exemplarily, the first end cover 10 and the second end cover 42 are respectively provided with a third groove 12 at the end face facing the medium cylinder 20, and a part of the gasket 60 is accommodated in the third groove 12, so as to keep the gasket 60 in the installed position. The depth of the third groove 12 can be the same as the depth of the second groove 11.

[0055] The third groove 12 can be spaced apart from the second groove 11, and the third groove 12 is located outside the second groove 11. In this way, the gasket 60 is located outside the sealing ring 50, which can reduce the material requirement for the gasket 60, and can further enhance the sealing effect.

[0056] In the axial direction of the medium cylinder 20, the difference between the thickness of the gasket 60 and the depth of the third groove 12 is slightly greater than or equal to the size increase of the medium cylinder 20 in this direction caused by thermal expansion under the maximum temperature difference of the medium cylinder 20.

[0057] The gasket 60 serves as a physical spacer, which ensures that the end face of the medium cylinder 20 does not directly contact the first end cover 10 and the second end cover 42, thereby creating a small gap between them, reserving space for the expansion of the medium cylinder 20, and preventing the medium cylinder 20 from being broken due to thermal expansion. Moreover, it can avoid the generation of abrasive particles caused by the direct contact between the medium cylinder 20 and the first end cover 10 and the second end cover 42.

[0058] In some embodiments, the upper part of the cavity 40 is provided with a first protective ring 421 extending upward, and the first protective ring 421 is located inside the medium cylinder 20, so as to prevent the plasma from eroding the sealing ring 50 located at the lower end of the medium cylinder 20. The outer diameter of the first protective ring 421 can be matched with the inner diameter of the medium cylinder 20.

[0059] Exemplarily, the second end cover 42 is provided with an opening through which the plasma can pass, and the inner diameter of the opening is smaller than the inner diameter of the medium cylinder 20, which facilitates the formation of the first protective ring 421 on the second end cover 42. In the radial direction of the medium cylinder 20, the wall thickness of the first protective ring 421 is the difference between the radius of the opening and the radius of the inner wall of the medium cylinder 20.

[0060] In the axial direction of the medium cylinder 20, the height of the first protective ring 421 can be greater than or equal to 5 mm and less than or equal to 10 mm. Exemplarily, the height of the first protective ring 421 can be 5 mm or 6 mm or 7 mm or 8 mm or 9 mm or 10 mm, which can not only meet the protection effect on the sealing ring 50 located at the lower end of the medium cylinder 20, but also facilitate the simplification of the structure of the second end cover 42 and the saving of the material of the second end cover 42.

[0061] In some embodiments, the first end cover 10 is provided with a downwardly extending boss 13, which is located inside the medium cylinder 20 and has an outer diameter matching the inner diameter of the medium cylinder 20, so as to prevent plasma from eroding the sealing ring 50 at the upper end of the medium cylinder 20.

[0062] In the axial direction of the medium cylinder 20, the boss 13 can have a height greater than or equal to 5 mm and less than or equal to 10 mm. For example, the boss 13 can have a height of 5 mm or 6 mm or 7 mm or 8 mm or 9 mm or 10 mm, so as to achieve the protection effect on the sealing ring 50 at the upper end of the medium cylinder 20 and facilitate the saving of the material of the first end cover 10.

[0063] In other embodiments, the lower part of the first end cover 10 is provided with a second protection ring extending downwardly, which is located inside the medium cylinder 20 and prevents plasma from eroding the sealing ring 50 at the upper end of the medium cylinder 20. The outer diameter of the second protection ring can match the inner diameter of the medium cylinder 20. The inner diameter of the second protection ring can be equal to the inner diameter of the first protection ring 421. The height of the second protection ring can be the same as the height of the first protection ring 421.

[0064] The other configurations of the plasma equipment of the above embodiments can adopt various technical solutions known to those skilled in the art at present and in the future, which will not be described in detail here.

[0065] In the description of the present specification, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0066] In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0067] In the present disclosure, unless specifically defined otherwise, the terms "mounting", "connection", "connecting", "fixed", and like terms should be construed broadly and, for example, can be a fixed connection, or detachable connection, or integral; can be a mechanical connection, or electrical connection, or communication; can be direct connection, or indirect connection through an intermediate medium; can be internal connection of two elements, or interaction relationship between two elements. The specific meanings of the above terms in the present disclosure can be understood by those skilled in the art according to the specific circumstances.

[0068] In the present disclosure, unless specifically defined otherwise, "on" or "under" of a first feature to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "over" of a first feature to a second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher than the second feature in horizontal height. "Under", "below" and "underneath" of a first feature to a second feature includes that the first feature is directly above and oblique above the second feature, or only indicates that the first feature is lower than the second feature in horizontal height.

[0069] The above disclosure provides many different embodiments or examples for implementing different structures of the present disclosure. In order to simplify the disclosure of the present disclosure, the components and settings of specific examples are described above. Of course, they are only examples, and the purpose is not to limit the present disclosure. In addition, the present disclosure can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0070] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto, and any skilled person in the art can easily think of various changes or replacements within the technical scope disclosed by the present disclosure, which should be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A plasma device, characterized by, The application relates to a plasma processing device, comprising: a dielectric cylinder; a first end cover, which covers an upper portion of the dielectric cylinder and forms a plasma generating space with the dielectric cylinder; a coil, which is sleeved outside the dielectric cylinder and is used for exciting a process gas into the plasma generating space to generate plasma; a cavity, which is located below the dielectric cylinder and has a workpiece processing space for processing a workpiece; wherein the dielectric cylinder, the first end cover and the cavity are respectively provided with a sealing ring; along the radial direction of the dielectric cylinder, the wall thickness of the dielectric cylinder is 2-4 times the wall thickness of the sealing ring; an end surface of the dielectric cylinder is provided with a first groove, and part of the sealing ring is accommodated in the first groove, and the surface area of the first groove is less than or equal to half the surface area of the sealing ring; the first end cover and the cavity are respectively provided with a second groove, and part of the sealing ring is accommodated in the second groove.

2. The plasma device of claim 1, wherein, along the radial direction of the dielectric cylinder, the wall thickness of the dielectric cylinder is 3 times the wall thickness of the sealing ring.

3. The plasma device of claim 1, wherein, along the axial direction of the dielectric cylinder, the depth of the first groove is less than one third of the height of the sealing ring.

4. The plasma device of claim 3, wherein, along the axial direction of the dielectric cylinder, the ratio of the depth of the first groove to the height of the sealing ring is greater than or equal to 0.16 and less than or equal to 0.

24.

5. The plasma device of claim 1, wherein, along the axial direction of the dielectric cylinder, the depth of the second groove is greater than one half of the height of the sealing ring.

6. The plasma device of claim 5, wherein, along the axial direction of the dielectric cylinder, the depth of the second groove is two thirds of the height of the sealing ring.

7. The plasma device of claim 1, wherein, the cross section of the first groove is semicircular, wherein the cross section is parallel to the axial direction of the dielectric cylinder.

8. The plasma device of claim 1, wherein, the cross section of the second groove is dovetail-shaped, wherein the cross section is parallel to the axial direction of the dielectric cylinder; wherein the distance between the opposite side walls of the second groove gradually decreases in the direction towards the dielectric cylinder.

9. The plasma device of claim 1, wherein, the end surface of the dielectric cylinder is respectively provided with a gasket, so that the dielectric cylinder is spaced apart from the first end cover and the cavity through the gasket; the gasket is spaced apart from the corresponding sealing ring and is located outside the corresponding sealing ring.

10. The plasma device of claim 1, wherein, an upper portion of the cavity is provided with a first protective ring extending upwards, and the first protective ring is located inside the dielectric cylinder; the outer diameter of the first protective ring is matched with the inner diameter of the dielectric cylinder; and / or, the first end cover is provided with a downwardly extending boss, and the outer diameter of the boss is matched with the inner diameter of the dielectric cylinder.

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