Multistage capacitive coupling plasma exciter

Abstract

The invention relates to the technical field of plasma sources, and discloses a multistage capacitance coupling plasma exciter, which comprises an excitation tube, a discharge electrode and a ground electrode, the excitation tube comprises m discharge sections and m + 1 ground electrode sections, and m is an integer not less than 1; the discharge sections and the ground pole sections are sequentially and alternately distributed along a preset first direction, and the two ends of each discharge section in the first direction are respectively provided with one ground pole section; at least part of the outer wall of each discharge section is covered with a discharge electrode, at least part of the outer wall of each earth pole section is covered with an earth pole electrode, and a gap exists between the adjacent discharge electrode and earth pole electrode; and the adjacent discharge electrode and earth electrode form an excitation site for exciting plasma on the excitation tube. The excitation tube wall isolates internal plasma from being in contact with the discharge electrode and the earth electrode, and electrode loss is avoided; the workpiece is prevented from serving as a dielectric barrier layer to guarantee the stability of the material removal process; the multi-stage regional electric field improves the plasma excitation efficiency and the workpiece removal efficiency.

Description

Technical Field

[0001] This application relates to the technical field of plasma sources, and particularly to a multi-stage capacitively coupled plasma exciter. Background Art

[0002] Plasma chemical vaporization machining uses capacitively coupled plasma. The electrode above the workpiece is connected to a high-frequency alternating voltage source, and the workpiece stage below the workpiece is a grounding electrode. Under the action of the alternating electric field, plasma is excited on the surface of the workpiece. After introducing a fluorine-containing gas, active fluorine radicals are generated, which react with the silicon-based material to form a volatile product, silicon tetrafluoride, thereby forming material removal. However, for this type of plasma source, the workpiece serves as a dielectric barrier layer, and its thickness affects the excitation state of the plasma; moreover, when the workpiece is a semiconductor material, arcs are likely to occur, greatly reducing the stability of the material removal process.

[0003] Generally speaking, there are still some other defects in the prior art: in the atmospheric capacitively coupled plasma source in the field of plasma chemical vaporization machining, the plasma directly contacts the electrode, resulting in electrode loss and the excitation state being affected by the workpiece thickness; the atmospheric inductively coupled plasma source has low processing stability due to its high-temperature characteristics; for the electric field concentrated plasma jet source, the electrode does not contact the plasma, greatly increasing the service life of the electrode, but the gas ionization rate is low, and the removal efficiency still needs to be improved. Summary of the Invention

[0004] Aiming at the defects in the prior art, this application proposes a multi-stage capacitively coupled plasma exciter, which improves the ionization efficiency by setting a multi-stage ionization structure; avoids using the workpiece as a dielectric layer to improve stability; and the electrode does not contact the plasma beam to extend the service life.

[0005] To solve the above problems, an embodiment of this application provides a multi-stage capacitively coupled plasma exciter, which is characterized in that it includes an excitation tube, a discharge electrode, and a ground electrode: the excitation tube includes m discharge segments and m + 1 ground electrode segments, where m is an integer not less than 1; the discharge segments and the ground electrode segments are alternately distributed in sequence along a preset first direction, and each discharge segment is provided with a ground electrode segment at both ends in the first direction;

[0006] At least part of the outer wall of each discharge segment is covered with a discharge electrode, at least part of the outer wall of each ground electrode segment is covered with a ground electrode, and there is a gap between the adjacent discharge electrode and the ground electrode;

[0007] The adjacent discharge electrode and the ground electrode form an excitation site for exciting plasma on the excitation tube. The excitation tube has m excitation sites, and the plasma forms a plasma jet after being excited m times in the first direction.

[0008] In some specific embodiments, the excitation tube further includes an insulating section, which is disposed between the adjacent discharge section and the ground electrode section, and the outer diameter of the insulating section is greater than the outer diameters of the discharge section and the ground electrode section; the number of the insulating sections is m.

[0009] In some specific embodiments, the outer diameter of the discharge electrode decreases from the end far away from the ground electrode towards the end close to the ground electrode, and the outer diameter of the ground electrode decreases from the end far away from the discharge electrode towards the end close to the discharge electrode.

[0010] In some specific embodiments, m = 1, the distance between the ground electrode and the discharge electrode close to the connection section is the electrode distance, the electrode distance is D1 millimeters, and the length of the discharge electrode is D2 millimeters; wherein, the value range of D1 is [2, 8], and the value range of D2 is [4, 8].

[0011] In some specific embodiments, the discharge electrode includes a left discharge fan ring and a right discharge fan ring. A left connecting arm extends from the side wall of the left discharge fan ring, and a right connecting arm extends from the side wall of the right discharge fan ring. The left connecting arm and the right connecting arm are locked by fasteners so that the left discharge fan ring and the right discharge fan ring are tightly fitted together to form the discharge electrode.

[0012] In some specific embodiments, it further includes a connecting ring, which includes a left connecting fan ring and a right connecting fan ring. The left connecting fan ring is connected to the left discharge fan ring through the left connecting arm, and the right connecting fan ring is connected to the right discharge fan ring through the right connecting arm. The left connecting arm and the right connecting arm are locked by fasteners so that the left connecting fan ring and the right connecting fan ring are combined into one body to form the connecting ring.

[0013] In some specific embodiments, it further includes an electrode holder, an insulating gasket, a radio frequency connector and a radio frequency connecting member; the connecting ring is sleeved on the end of the radio frequency connecting member, the first end of the radio frequency connecting member is connected to the output end of the radio frequency connector, and the input end of the radio frequency connector can be externally connected to a voltage source; the radio frequency connector is disposed on the insulating gasket, and the insulating gasket is disposed on the electrode holder.

[0014] In some specific embodiments, it further includes a base, and an air inlet for externally connecting an air source is provided on the side wall of the base, and a communication hole communicated with the air inlet is provided at the bottom end of the base; the excitation tube includes a connecting section, and the connecting section is sleeved on the inner wall of the communication hole and is communicated with the air inlet through the communication hole.

[0015] In some specific embodiments, it further includes an electrode holder, a metal gasket, and a ground electrode connector; the electrode holder and the top end of the base are connected through the metal gasket, and the ground electrode closest to the connection section is fixedly connected to the bottom end of the base; the first end of the ground electrode connector is connected to the electrode holder, and a ground electrode arm is extended and provided on the side wall of the ground electrode that does not contact the base, and the ground electrode arm is connected to the ground electrode connector.

[0016] In some specific embodiments, when D2 is 6 mm, a relationship curve between the electrode spacing and the radio frequency power is obtained, and a constraint condition for a double-stage excited plasma jet is constructed according to the plasma excitation state and the relationship curve;

[0017] The expression of the relationship curve is:

[0018] P = 1.25D 1 2 + 0.5D 1 + 115

[0019] Wherein, P represents the radio frequency power, D 1 represents the electrode spacing, a is the quadratic coefficient, b is the linear coefficient, and c is the constant term;

[0020] The constraint condition specifically includes:

[0021] When the excitation power exceeds the relationship curve, the plasma excitation state is excitation;

[0022] When the excitation power is lower than the relationship curve, the plasma excitation state is non-excitation.

[0023] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0024] (1) By correspondingly installing discharge electrodes at each discharge section of the excitation tube and correspondingly installing ground electrodes at each ground electrode section of the excitation tube, an area electric field is formed between the discharge electrodes and the ground electrodes, and the gas flowing through this area electric field in the excitation tube is ionized and excited to obtain a plasma beam; the tube wall of the excitation tube naturally isolates the contact between the plasma and the discharge electrodes and the ground electrodes, and the plasma does not contact the discharge electrodes or the ground electrodes during the plasma excitation process, solving the problem of plasma contact causing loss to the electrodes in plasma chemical vaporization processing and extending the service life of the electrodes.

[0025] (2) By arranging the discharge sections between adjacent ground electrode sections, and ensuring that the number of ground electrode sections is always one more than that of the discharge sections, it is guaranteed that the electrode closest to the plasma beam output end of the excitation tube must be the ground electrode, avoiding using the workpiece as a dielectric barrier layer, preventing the excitation state of the plasma from being affected by the workpiece thickness; ensuring that the gas can excite a stable plasma beam and then spray it onto the workpiece for processing; even when removing materials from a workpiece made of semiconductor material, it can effectively avoid generating arcs, preventing the plasma beam from being heated and raised in temperature, and ensuring the stability during the material removal process.

[0026] (3) By setting the number of discharge sections to m and the number of ground electrode sections to m + 1, where m ≥ 1, a multi-stage regional electric field is formed to repeatedly excite the gas flowing through the excitation tube. The lower-level electric field excites the gas that was not excited in the upper-level regional electric field, and at the same time re-ionizes the ions that became inactivated after being excited in the upper-level regional electric field. Compared with single-stage excitation, it can effectively increase the gas ionization rate to improve the material removal efficiency of the workpiece. Brief Description of the Drawings

[0027] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0028] Figure 1 Isometric view of the multi-stage capacitive coupling plasma exciter provided by the present application;

[0029] Figure 2 Cross-sectional view of the multi-stage capacitive coupling plasma exciter provided by the present application passing through the central axis of the excitation tube;

[0030] Figure 3 Schematic cross-sectional structure diagram when the excitation tube is installed on the base;

[0031] Figure 4 Schematic cross-sectional structure diagram of the base;

[0032] Figure 5 Schematic cross-sectional structure diagram when the discharge electrode and the ground electrode are installed on the excitation tube;

[0033] Figure 6 Schematic structure diagram of the excitation tube;

[0034] Figure 7 Schematic structure diagram of the discharge electrode;

[0035] Figure 8 Schematic diagram of secondary excitation capacitive coupling plasma;

[0036] Figure 9 Classification of plasma excitation states based on different electrode spacings and power regulation.

[0037] Description of main component symbols:

[0038] 1. Excitation tube, 11. Connection section, 12. Excitation section, 121. Discharge section, 122. Ground electrode section, 123. Insulation section, 2. Discharge electrode, 21. Left discharge fan ring, 22. Left connecting arm, 23. Left connecting fan ring, 24. Right discharge fan ring, 25. Right connecting arm, 26. Right connecting fan ring, 3. Ground electrode, 31. Ground electrode arm, 4. Base, 41. Air inlet hole, 42. Communication hole, 5. RF connector, 6. Insulating gasket, 7. Electrode holder, 8. Metal gasket, 9. RF connector, 10. Ground electrode connector, 01. First outer side, 02. Second outer side. Detailed implementation manners

[0039] Hereinafter, various embodiments of the present disclosure will be described more fully. The present disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of the present disclosure to the specific embodiments disclosed herein, but the present disclosure should be understood to cover all adjustments, equivalents, and / or alternative solutions falling within the spirit and scope of the various embodiments of the present disclosure.

[0040] Hereinafter, the term "comprise" or "may comprise" that may be used in various embodiments of the present disclosure indicates the presence of the disclosed functions, operations, or elements, and does not limit the addition of one or more functions, operations, or elements. Further, as used in various embodiments of the present disclosure, the terms "comprise", "have" and their cognates are only intended to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing items, and should not be construed as precluding the existence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing items first.

[0041] In various embodiments of the present disclosure, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the listed words. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0042] Expressions used in various embodiments of the present disclosure (such as "first", "second", etc.) may modify various components in the various embodiments, but do not limit the corresponding components. For example, the above expressions do not limit the order and / or importance of the components. The above expressions are only for the purpose of distinguishing one component from other components. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of the present disclosure, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

[0043] It should be noted that: if it is described that one component is "connected" to another component, the first component may be directly connected to the second component, and a third component may be "connected" between the first component and the second component. Conversely, when one component is "directly connected" to another component, it can be understood that there is no third component between the first component and the second component.

[0044] The term "user" used in various embodiments of the present disclosure may indicate a person using an electronic device or a device using an electronic device (for example, an artificial intelligence electronic device).

[0045] The terms used in various embodiments of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the various embodiments of the present disclosure. As used herein, the singular form is intended to also include the plural form unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the various embodiments of the present disclosure belong. The terms (such as those defined in a commonly used dictionary) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning unless clearly defined in the various embodiments of the present disclosure.

[0046] Embodiment 1:

[0047] This embodiment provides a multi-stage capacitive coupling plasma exciter, as Figures 1 to 7 shown, including: an excitation tube 1 as Figure 6 shown; the excitation tube 1 includes a connection section 11 and an excitation section 12 connected in sequence according to the gas flow direction. The connection section 11 is externally connected to a gas source, and the gas is excited into plasma in the excitation section 12. The excitation section 12 further includes a discharge section 121 and a ground electrode section 122. The number of discharge sections 121 is m, the number of ground electrode sections 122 is m + 1, and m ≥ 1. The discharge section 121 is disposed between adjacent ground electrode sections 122;

[0048] AsFigure 7 The discharge electrode 2 shown in the figure is sleeved on the outer wall of the discharge section 121 one by one, and the discharge electrode 2 is set to be connectable to an AC voltage source;

[0049] As Figure 5 shown in the figure, the ground electrode 3 is sleeved on the outer wall of the ground electrode section 122 one by one, and the ground electrode 3 is set to be connectable to a ground electrode;

[0050] The adjacent discharge electrodes 2 and ground electrodes 3 are arranged at intervals.

[0051] In this embodiment, the connection section 11 of the excitation tube 1 is set to be externally connectable to a gas source, and the gas output end of the connection section 11 is connected to the gas input end of the excitation section 12; on the excitation section 12, the ground electrode sections 122 and the discharge sections 121 are arranged in a staggered manner along the gas flow direction. The ground electrode 3 is sleeved on the outer wall of the ground electrode section 122, and the discharge electrode 2 is sleeved on the outer wall of the discharge section 121. An area electric field is formed between the powered discharge electrode 2 and the ground electrode 3 to ionize the substances flowing through the area electric field in the excitation section 12 correspondingly; there is always one more ground electrode section 122 than the discharge section 121, and the discharge section 121 is always arranged between adjacent ground electrode sections 122. This setting ensures that the ground electrode section 122 must be at the end of the excitation section 12, avoiding using the workpiece as a dielectric barrier layer, ensuring that the gas excitation process is completed in the excitation section 12 and then sprayed onto the workpiece surface in the form of a plasma beam. In this case, using the workpiece as a dielectric barrier layer is avoided, and the excitation state of the plasma is not affected by the uncontrollable workpiece thickness, ensuring that a stable plasma beam can be excited from the gas; even when removing materials from a workpiece made of semiconductor material, it can effectively avoid generating arcs and will not cause the plasma beam to be heated and temperature to rise, ensuring the stability during the material removal process.

[0052] In this application, at least a part of the outer wall of each discharge section 121 is covered with a discharge electrode 2, at least a part of the outer wall of each ground electrode section 122 is covered with a ground electrode 3, and there is a gap between the adjacent discharge electrodes 2 and the ground electrodes 3; the adjacent discharge electrodes 2 and the ground electrodes 3 form an excitation site for exciting plasma on the excitation tube. The excitation tube has m excitation sites, and the plasma forms a plasma jet after being excited m times in the first direction. The discharge electrode 22 and the ground electrode 33 are sleeved on the outer wall of the excitation section 12. The tube wall of the excitation tube 1 naturally isolates the contact between the plasma and the discharge electrode 22 and the ground electrode 33, solves the problem of plasma contact causing loss to the electrode in plasma chemical vaporization machining, and extends the service life of the electrode.

[0053] The excitation section 12 includes a discharge section 121 and a ground electrode section 122. The number of discharge sections 121 is m, and the number of ground electrode sections 122 is m + 1, where m ≥ 1. The discharge sections 121 are arranged between adjacent ground electrode sections 122, and the discharge electrodes 2 are sleeved outside the discharge sections 121 one by one, and the ground electrode electrodes 3 are sleeved outside the electrode sections one by one. A first-stage regional electric field for exciting plasma is formed between the discharge electrode 2 and the adjacent ground electrode 3; when m takes the minimum value of 1, there are two stages of regional electric fields for exciting plasma; when m takes 2, there are three stages of regional electric fields for exciting plasma; as the value of m increases, the number of stages of the regional electric field for exciting plasma is always correspondingly m + 1 levels; in the multi-stage regional electric fields, the lower-level regional electric field can excite the gas that has not been excited by the upper-level regional electric field and re-ionize the active ions that have been inactivated after being excited by the upper-level regional electric field; compared with single-stage excitation, it can effectively improve the gas ionization rate to improve the workpiece removal efficiency.

[0054] Embodiment 2:

[0055] Embodiment 2 is further optimized and implemented on the basis of Embodiment 1, as Figure 6 shown, the excitation section 12 further includes an insulating section 123. The insulating section 123 is arranged between adjacent discharge sections 121 and ground electrode sections 122, and the outer diameter of the insulating section 123 is greater than the outer diameters of the discharge section 121 and the ground electrode section 122; the number of insulating sections 123 is 2m.

[0056] In this embodiment, the excitation tube 1 is made of a material with a dielectric constant greater than that of air. The insulating section 123, which is part of the excitation tube 1, is arranged between adjacent discharge sections 121 and ground electrode sections 122, and the outer diameter of the insulating section 123 is greater than those of the discharge section 121 and the ground electrode section 122, increasing the capacitance and avoiding the breakdown of the air between the discharge electrode 2 and the ground electrode 3, which would cause a reduction in the excitation efficiency.

[0057] The rest of this embodiment is the same as that of Embodiment 1, so it will not be elaborated here.

[0058] Embodiment 3:

[0059] Embodiment 3 is implemented on the basis of Embodiment 2, as Figure 5 shown, the outer diameter of the discharge electrode 2 decreases from the end far from the ground electrode 3 to the end close to the ground electrode 3, and the outer diameter of the ground electrode 3 decreases from the end far from the discharge electrode 2 to the end close to the discharge electrode 2.

[0060] In this embodiment, the first outer side surface 01 of the discharge electrode 2 and the second outer side surface 02 of the ground electrode 3 are inclined, avoiding the occurrence of tip discharge due to the presence of overly close sharp corners in the region where the insulating effect of the insulating section 123 becomes weak between the mutually approaching discharge electrode 2 and ground electrode 3.

[0061] When an insulating section 123 is provided between the discharge section 121 and the ground electrode section 122, the difficulty of arc breakdown between the ground electrode 3 and the discharge electrode 2 decreases in the direction outward along the outer wall of the excitation tube 1; the first outer side surface 01 and the second outer side surface 02, which are chamfered inclined surfaces, are provided at the ends of the discharge electrode 2 and the ground electrode 3 that are close to each other. That is, along the direction in which the difficulty of arc breakdown decreases, the distance between the discharge electrode 2 and the ground electrode 3 is gradually increased, increasing the difficulty of breakdown due to the generation of an arc bypassing the insulating section 123 between the discharge electrode 2 and the ground electrode 3, so that the breakdown limits at various parts of the discharge electrode 2 and the ground electrode 3 remain relatively consistent.

[0062] The remaining parts of this embodiment are the same as those of Embodiment 2, so they will not be described again.

[0063] Embodiment 4:

[0064] Embodiment 4 is implemented on the basis of Embodiment 3. As Figure 5 shown, the included angle formed between the extension lines of the first outer side surface 01 on the discharge electrode 2 and the second outer side surface 02 on the ground electrode 3 is an obtuse angle, and this included angle is represented by α in Figure 5 .

[0065] The remaining parts of this embodiment are the same as those of Embodiment 3, so they will not be described again.

[0066] Embodiment 5:

[0067] Embodiment 5 is implemented on the basis of any one of Embodiments 1 to 4. As Figure 7 shown, the discharge electrode 2 includes a left discharge fan ring 21 and a right discharge fan ring 24. A left connecting arm 22 is extended from the side wall of the left discharge fan ring 21, and a right connecting arm 25 is extended from the side wall of the right discharge fan ring 24. The left connecting arm 22 and the right connecting arm 25 are locked by fasteners so that the left discharge fan ring 21 and the right discharge fan ring 24 are fastened and fitted together to form the discharge electrode 2.

[0068] In this embodiment, compared with the closed-loop discharge electrode 2, the split structure enables it to adapt to more installation scenarios. For example, when there are structures with inner diameters larger than that of the discharge electrode 2 at both ends of the installation location of the discharge electrode 2, the split-structure discharge electrode 2 can have better scenario adaptability; at the same time, by extending the left connecting arm 22 and the right connecting arm 25 from the side walls of the left discharge fan ring 21 and the right discharge fan ring 24 to the distal ends and locking the left connecting arm 22 and the right connecting arm 25, the left discharge fan ring 21 and the right discharge fan ring 24 are fitted together, avoiding directly fastening the fasteners on the left discharge fan ring 21 and the right discharge fan ring 24, and preventing the extra fasteners from changing the distance between the discharge electrode 2 and the ground electrode 3 and increasing the breakdown risk.

[0069] The remaining parts of this embodiment are the same as any one of Embodiments 1-4, so they will not be described again.

[0070] Embodiment 6:

[0071] Embodiment 6 is implemented on the basis of Embodiment 5. As Figure 7 shown, it includes a connecting ring. The connecting ring includes a left connecting sector ring 23 and a right connecting sector ring 26. The left connecting sector ring 23 is connected to the left discharge sector ring 21 through a left connecting arm 22, and the right connecting sector ring 26 is connected to the right discharge sector ring 24 through a right connecting arm 25. The left connecting arm 22 and the right connecting arm 25 are locked by fasteners so that the left connecting sector ring 23 and the right connecting sector ring 26 are combined into one body to form a connecting ring.

[0072] In this embodiment, the connecting ring is a split structure, and is locked by the left connecting arm 22, the right connecting arm 25 and the fasteners thereon to combine the left connecting sector ring 23 and the right connecting sector ring 26 into one body; in addition to being able to adapt to the installation scenario where there are structures larger than the inner diameter of the connecting ring at both ends of the connecting ring, only by locking the left connecting arm 22 and the right connecting arm 25 once, the synchronous locking of the discharge electrode 2 and the connecting ring can be realized. In the case of installing multiple discharge electrodes 2, the installation efficiency can be greatly improved.

[0073] The remaining parts of this embodiment are the same as those of Embodiment 5, so they will not be described again.

[0074] Embodiment 7:

[0075] The embodiment is implemented on the basis of Embodiment 6. As Figure 1 shown, it further includes an electrode holder 7, an insulating gasket 6, a radio frequency connector 5 and a radio frequency connecting member 9; the connecting ring is sleeved on the end of the radio frequency connecting member 9, the head end of the radio frequency connecting member 9 is connected to the output end of the radio frequency connector 5, and the input end of the radio frequency connector 5 can be externally connected to an AC voltage source; the radio frequency connector 5 is arranged on the insulating gasket 6, and the insulating gasket 6 is arranged on the electrode holder 7.

[0076] In this embodiment, the electrode holder 7 and the radio frequency connector 5 are isolated by the insulating gasket 6 to prevent the leakage of the AC voltage source and the short circuit with the electrode holder 7. The output end of the radio frequency connector 5 is connected through the radio frequency connecting member 9, and the rod-shaped radio frequency connecting member 9 can be conveniently connected to the discharge; it provides the possibility of connecting multiple discharge electrodes 2 through one radio frequency connecting member 9.

[0077] The remaining parts of this embodiment are the same as those of Embodiment 6, so they will not be described again.

[0078] Embodiment 8:

[0079] Embodiment 8 is implemented on the basis of any one of Embodiments 1 to 7. As Figure 3 、 Figure 4As shown in the figure, it further includes a base 4. An air inlet hole 91 for connecting an external air source is provided on the side wall of the base 4, and a communication hole 92 communicating with the air inlet hole 91 is provided at the bottom end of the base 4; the excitation tube 1 includes a connection section 11, and the connection section 11 is sleeved on the inner wall of the communication hole 92 and communicates with the air inlet hole 91 through the communication hole 92.

[0080] An external air source is connected through the air inlet hole 91 on the base 4, and the outer wall of the connection section 11 of the excitation tube 1 is sleeved and installed through the communication hole 92 of the base 4. While fixing the excitation tube 1, the air inlet hole 91 and the excitation tube 1 are communicated, so that gas can enter the excitation tube 1 through the communication hole 92.

[0081] The rest of this embodiment is the same as any one of Embodiments 1 to 7, so it will not be described in detail.

[0082] Embodiment 9:

[0083] Embodiment 9 is implemented on the basis of Embodiment 8. As Figure 2 shown in the figure, it further includes an electrode holder 7, a metal gasket 8, and a ground electrode connector; the electrode holder 7 and the top end of the base 4 are connected through the metal gasket 8, and the ground electrode 3 closest to the connection section 11 is fixedly connected to the bottom end of the base 4; the head end of the ground electrode connector 10 is connected to the electrode holder 7, and a ground electrode arm 31 is extended and provided on the side wall of the ground electrode 3 that does not contact the base 4, and the ground electrode arm 31 is connected to the ground electrode connector 10.

[0084] There is a base 4 with a conductive function, and its bottom end is connected to the first-stage ground electrode 3. A metal gasket 8 is arranged between the top end of the base 4 and the electrode holder 7 to increase the fitting area between the base 4 and the electrode holder 7, so that the first-stage ground electrode 3 can be grounded through the base 4 and the metal gasket 8 to the electrode holder 7 in sequence.

[0085] The rest of this embodiment is the same as Embodiment 8, so it will not be described in detail.

[0086] Embodiment 10:

[0087] Embodiment 10 is implemented on the basis of any one of Embodiments 1 to 9. As Figure 5 shown in the figure, m = 1, the distance between the ground electrode 3 close to the connection section 11 and the discharge electrode 2 is D1 millimeters, and the length of the discharge electrode 2 is D2 millimeters; among them, the value range of D1 is [2, 8], and the value range of D2 is [4, 8].

[0088] The rest of this embodiment is the same as any one of Embodiments 1 to 9, so it will not be described in detail.

[0089] Embodiment 11:

[0090] Embodiment 11 is implemented on the basis of Embodiment 10. The specific scheme includes:

[0091] When D2 is 6 mm, obtain the relationship curve between the electrode spacing and the radio frequency power, and construct the constraint conditions for the double-stage excited plasma jet according to the plasma excitation state and the relationship curve;

[0092] The expression of the relationship curve is:

[0093] P = 1.25D 1 2 + 0.5D 1 + 115

[0094] where P represents the radio frequency power, D 1 represents the electrode spacing, a is the quadratic coefficient, b is the linear coefficient, and c is the constant term;

[0095] The constraint conditions specifically include:

[0096] When the excitation power exceeds the relationship curve, the plasma excitation state is excitation;

[0097] When the excitation power is lower than the relationship curve, the plasma excitation state is non-excitation.

[0098] The solution of this embodiment is developed for the case of m = 2. When m = 2, secondary excitation capacitive coupling is formed, the excitation tube has two excitation sites, and the plasma forms a plasma jet after being excited twice in the first direction. Moreover, the interval D2 between the two excitation points is 6 mm. When D2 is 6 mm, it is the optimal size. When the D2 parameter changes, there will be different rules for the influence of D1 regulation on the plasma jet characteristics. If D2 is too small, the excitation points are too close to each other and will affect each other, resulting in a weaker plasma; if D2 is too large, the plasma deactivation behavior is enhanced, making the concentration of active particles smaller.

[0099] Figure 8 The figure shows a schematic diagram of secondary excitation capacitive coupling plasma. The secondary excitation plasma jet adopts the arrangement of ground electrode - excitation electrode - ground electrode from top to bottom, and two plasma excitation sites can be obtained. After the plasma is excited at the upper excitation site, it is excited again at the lower site, and a plasma jet is formed through two excitations.

[0100] In the design of a multi-stage excited capacitive coupling plasma jet source, the more the number of stages, the more the excitation sites, but the smaller the electric field energy of each excitation site. Therefore, an experimental demonstration was carried out on whether the design idea of double-stage excitation can improve the actual processing efficiency. A single-stage excitation and a double-stage excitation capacitive coupling plasma jet source were built, and their jet characteristics and actual processing effects were compared. In order to more clearly display the plasma morphology, the beam nozzle material used in the experiment is glass. However, in the actual processing process, the glass will react with the etching radicals of the plasma and be corroded. Therefore, ceramic nozzles are used in actual processing.

[0101] In the experiment, only helium gas was introduced for excitation. It can be seen that there is only one excitation site for single-stage excitation, while there are two excitation sites for double-stage excitation. Since the excitation gas first passes through the upper excitation site and then through the lower excitation site, the gas will be excited at the upper excitation point first. The ionized active groups and gas molecules are transported together to the lower excitation site for secondary ionization. At the same time, the free electrons in the plasma are accelerated again and collide with the carbon tetrafluoride gas molecules. The temperature at the position corresponding to the excitation point on the ceramic tube was measured by an infrared thermal imager to characterize the excitation intensity of the plasma, and the temperatures of different excitation points in single-stage excitation and double-stage excitation were compared. From the temperature measurement results, it can be seen that the temperature of the upper excitation point in double-stage excitation is lower than that of the excitation point in single-stage excitation, which means that the free electron density in double-stage excitation is lower during the first excitation, and the collision frequency with other particles is relatively weaker. This is because under the condition of the same power input, the energy fed into the double-stage excitation plasma is distributed to the two excitation points, so the energy obtained by each excitation point is smaller than that of the single excitation point in single-stage excitation. However, after the second excitation, in the power range of 120W to 150W, the temperature of the lower excitation point in double-stage excitation is 20 to 30 °C higher than that of the single excitation point. This indicates that after the gas is pre-ionized during the first excitation process, the active radicals and un-ionized gas can generate more secondary electrons during the second excitation process, thereby enhancing the collision frequency between the secondary electrons and other particles and promoting the dissociation of more active particles.

[0102] In addition, the active particle components of the single-stage excitation plasma and the double-stage excitation plasma were analyzed to obtain the optical emission spectrum (OES) under different gas species mixtures. When pure helium gas was introduced, the plasma showed a purple color, and strong He peaks and N2 peaks from the external environment were detected. After adding CF 4 , the plasma jet turned green, and multiple obvious fluorine radical peaks were detected in the wavelength range of 620nm - 760nm. In addition, peaks corresponding to CFx (x = 1, 2, 3) and C2 groups were also detected. In this case, deposition is likely to occur on the processed workpiece. After introducing O 2 , it can effectively inhibit the dissociation of carbon fluoride groups and C2 groups, thereby promoting the generation of fluorine radicals and increasing the etching rate. The plasma jet also turned orange. In the removal process based on chemical etching reaction, the material removal is mainly based on active fluorine radicals, which mainly come from the dissociation of CF4:

[0103] CF 4 +e → CF 3 +F+e

[0104] CF 4 +e → CF 2 +2F+e

[0105] The CFx group dissociates into fluorine radicals and a new CFx group accordingly. The spectral intensities of the CFx peak at 387.2 nm and the F peak at 739.9 nm are extracted from the plasma jet outside the ceramic tube. According to the measurement results, the intensity ratio of F to CFx in the DIPJ (average value of 2.06) is greater than that in the SIPJ (average value of 1.37), indicating that more active F radicals are dissociated from the CFx group in the plasma jet after secondary excitation. To reveal the difference in the composition of active radicals after single-stage excitation and double-stage excitation, the spectra at the excitation positions are further measured. The measurement results show that the excitation point of single-stage excitation and the upper excitation point of double-stage excitation exhibit the same I F / I CFx , because the first excitation is performed at these positions. After the second ignition, I F / I CFx increases significantly compared with the first ignition. At different powers, the measurement results show the same change, which can be explained by the bond energies of different reactants. Assuming that active F radicals dissociate from CF4 molecules, the theoretical bond energy of CF3-F is 546.9 kJ / mol, which is the energy required to break the chemical bond. For the CFx groups, they all have relatively low bond energies (CF2-F: 359 kJ / mol, CF-F: 506 kJ / mol, C-F: 513.8 kJ / mol). This means that F radicals are more easily dissociated by the CFx group rather than by CF4 dissociation. On the one hand, as described above, the plasma ignition intensity is enhanced by the double-stage excitation strategy. On the other hand, after the first ignition at the upper ignition position, the substances flowing through the lower ignition position include non-ionized CF4 and CFx groups, which are more likely to dissociate into more active fluorine radicals by colliding with high-energy electrons. Therefore, temperature and OES analyses show that the electron collision and fluorine radical dissociation are effectively enhanced by the double-stage excitation strategy, thereby increasing the generation of active radicals.

[0106] Therefore, under the same parameters, the etching rate of the double-stage excitation plasma source is higher than that of the single-stage excitation plasma source, verifying the superiority of double-stage excitation over single-stage excitation in processing ability, and it can be extended to the design of plasma sources with higher excitation levels to further improve the processing efficiency of the plasma source.

[0107] Moreover, the double-stage excitation strategy optimization based on the regulation of the electric field intensity in this embodiment is as follows:

[0108] At the electrode spacing D 1Under the condition that the length is 2 mm, the electric field strengths of the two excitation points are the same, and the gas flows vertically downward. The mixed gas is first ionized at the upper excitation point, and then the remaining gas is ionized when passing through the lower excitation point. Therefore, the excitation intensity of the upper excitation point will be stronger than that of the lower excitation point. For the free electrons ionized at the upper excitation point, after being inactivated over a certain distance, the remaining electrons will be accelerated again at the lower excitation point. They collide with the reaction gas to dissociate active F atoms, and then diffuse downward. Therefore, this part of the electrons experiences two inactivation processes. However, for the free electrons ionized at the lower excitation point, they only experience one inactivation process, and the inactivation distance from the lower excitation point to the sample is shorter than that from the upper excitation point to the sample. Here, adjust D 1 Length, that is, the electrode spacing of the upper excitation point. By changing this structural parameter, the electric field strengths of the two excitation points can be adjusted, thereby changing the excitation states of the two excitation points.

[0109] At a radio frequency power of 140 W, D 1 Under the condition that the length is 8 mm, the electric field strength of the upper excitation point is not sufficient to excite the plasma, and only shows the function of single-stage excitation. However, when the radio frequency power increases to 200 W, the increase in the electric field strength enables the plasma to exhibit normal two-stage excitation characteristics. According to the plasma brightness, it can be judged that the plasma excitation intensity of the upper excitation point decreases with the increase of D 1 Length, while the excitation intensity of the lower excitation point increases. This is because the gas ionized at the upper excitation point decreases, while the gas ionized at the lower excitation point increases. The experimental results show that in the radio frequency power range of 140 W - 180 W, the material removal rate first increases and then decreases with the increase of D 1 Length. Under the condition that the plasma jet source has dual excitation characteristics, the removal rate continuously increases with the increase of D 1 Length, and the plasma state corresponding to the condition of the decreasing removal rate is exactly the condition where the upper excitation point cannot excite the plasma. When the excitation power is set to 200 W, the material removal rate shows a continuous upward trend. The reason is that when D 1 Length is in the range of 2 mm - 8 mm, the plasma jet source can exhibit normal two-stage excitation characteristics. Based on the observation of the plasma excitation state and the statistical processing efficiency obtained from the experiment, the following conclusions can be drawn: Increasing D 1 Length can significantly improve the processing efficiency of the two-stage excitation plasma jet source, but the prerequisite for improving the efficiency is to provide sufficient excitation power to ionize the gas at the upper excitation point and exhibit two-stage excitation characteristics.

[0110] To verify the increase of D 1The effect of length on improving processing efficiency was studied by optical emission spectroscopy to analyze the active particle components under different conditions. According to the measurement results, multiple peaks of active fluorine radicals could be clearly detected in the wavelength range of 620 nm - 760 nm. In addition, peaks corresponding to helium, CFx, C2 deposition, and nitrogen in the surrounding environment were also detected. The peak intensity of fluorine radicals at a wavelength of 739.9 nm was extracted to analyze the change in the concentration of fluorine radicals under different D 1 length conditions. When the excitation power was 140 W - 180 W, the peak intensity of fluorine radicals first increased and then decreased with the increase in D 1 length. However, when the excitation power was adjusted to 200 W, the peak intensity of fluorine radicals showed a continuous upward trend with the increase in D 1 length, which was consistent with the change rule of processing efficiency, strongly verifying the significant effect of increasing D 1 length on increasing the concentration of etching radicals and processing efficiency. In previous studies, in the range where the full width at half maximum of the removal function was about 2 - 5 mm, the range of the removal rate was usually 0.05 - 0.25 mm 3 / min. Therefore, based on the analysis results of the removal rate, the experimental conditions with a removal rate greater than 0.25 mm 3 / min were defined as the strong excitation state, corresponding to a peak intensity greater than 6000. For the plasma excitation states under different conditions, we further divided the conditions with a peak intensity less than 6000. When the dual excitation characteristics were exhibited, the plasma jet source showed a weak excitation state, and when the upper excitation point could not be excited, we defined it as the non-excitation state. Based on the above classification criteria, Figure 9 the excitation states under different conditions were revealed. When D 1 was 2 mm and 4 mm, the plasma showed a weak excitation state. When D 1 continued to increase, the plasma gradually changed into two extreme states: strong excitation and non-excitation. When the power was insufficient, the upper excitation point could not be excited, and when the power was high enough, a strong plasma jet with a high concentration of active particles could be formed.

[0111] Those skilled in the art can understand that the drawings are only schematic diagrams of a preferred implementation scenario, and the modules or processes in the drawings are not necessarily essential for implementing the present invention.

[0112] Those skilled in the art can understand that the modules in the device in the implementation scenario can be distributed in the device of the implementation scenario according to the description of the implementation scenario, or can be correspondingly changed and located in one or more devices different from the present implementation scenario. The modules of the above implementation scenario can be combined into one module, or can be further split into multiple sub-modules.

[0113] The serial numbers of the present invention above are only for description and do not represent the advantages or disadvantages of the implementation scenarios.

[0114] The above are only several specific implementation scenarios of the present invention. However, the present invention is not limited thereto, and any changes that can be conceived by those skilled in the art shall fall within the protection scope of the present invention.

Claims

1. A multi-stage capacitively coupled plasma exciter, characterized in that: The device comprises an excitation tube, a discharge electrode and a ground electrode: the excitation tube comprises m discharge segments and m+1 ground segments, where m is an integer not less than 1; the discharge segments and the ground segments are alternately distributed in sequence along a preset first direction, and each discharge segment is provided with a ground segment at both ends of the first direction; At least part of the outer wall of each of the discharge segments is covered with a discharge electrode, at least part of the outer wall of each of the ground electrode segments is covered with a ground electrode, and there is a gap between adjacent discharge electrodes and ground electrodes; The adjacent discharge electrodes and the ground electrodes form an excitation site for exciting plasma on the excitation tube. The excitation tube has m excitation sites. The plasma forms a plasma jet after being excited m times in the first direction.

2. The multi-stage capacitively coupled plasma excitation device according to claim 1, characterized in that: The excitation tube further includes an insulating segment, which is arranged between the adjacent discharge segment and the ground segment, and the outer diameter of the insulating segment is larger than the outer diameter of the discharge segment and the outer diameter of the ground segment; the number of the insulating segments is m.

3. The multi-stage capacitively coupled plasma excitation device according to claim 2, characterized in that: The outer diameter of the discharge electrode decreases from an end away from the ground electrode to an end close to the ground electrode, and the outer diameter of the ground electrode decreases from an end away from the discharge electrode to an end close to the discharge electrode.

4. The multi-stage capacitively coupled plasma exciter according to claim 1 or 2, characterized in that: m=1, the distance between the ground electrode close to the connecting segment and the discharge electrode is the electrode distance, the electrode distance is D1 mm, and the length of the discharge electrode is D2 mm; wherein the value interval of D1 is [2, 8], and the value interval of D2 is [4, 8].

5. The multi-stage capacitively coupled plasma exciter according to claim 1 or 2, characterized in that: The discharge electrode comprises a left discharge fan ring and a right discharge fan ring, wherein a left connecting arm is extended from the side wall of the left discharge fan ring, and a right connecting arm is extended from the side wall of the right discharge fan ring, and the left connecting arm and the right connecting arm are locked by fasteners so that the left discharge fan ring and the right discharge fan ring are fastened and fitted together to form the discharge electrode as a whole.

6. The multi-stage capacitively coupled plasma excitation device according to claim 5, characterized in that: It also includes a connecting ring, which includes a left connecting fan ring and a right connecting fan ring. The left connecting fan ring is connected to the left discharge fan ring through the left connecting arm, and the right connecting fan ring is connected to the right discharge fan ring through the right connecting arm. The left connecting arm and the right connecting arm are locked by fasteners to integrate the left connecting fan ring and the right connecting fan ring into one to form the connecting ring.

7. The multi-stage capacitively coupled plasma igniter according to claim 6, characterized in that: It also includes an electrode frame, an insulating gasket, a radio frequency connector and a radio frequency connector; the connecting ring is sleeved on the end of the radio frequency connector, the head end of the radio frequency connector is connected to the output end of the radio frequency connector, and the input end of the radio frequency connector can be externally connected to a voltage source; the radio frequency connector is arranged on the insulating gasket, and the insulating gasket is arranged on the electrode frame.

8. The multi-stage capacitively coupled plasma exciter according to claim 1 or 2, characterized in that: It also includes a base, the side wall of the base is provided with an air inlet for an external air source, and the bottom end of the base is provided with a connecting hole connected to the air inlet; the excitation tube includes a connecting section, the connecting section is sleeved on the inner wall of the connecting hole, and is connected to the air inlet through the connecting hole.

9. The multi-stage capacitively coupled plasma igniter according to claim 8, characterized in that: It also includes an electrode frame, a metal gasket, and a ground electrode connector; the electrode frame and the top end of the base are connected via the metal gasket, and the ground electrode closest to the connecting section is fixedly connected to the bottom end of the base; the head end of the ground electrode connector is connected to the electrode frame, and a ground electrode arm is extended from the side wall of the ground electrode that is not in contact with the base, and the ground electrode arm is connected to the ground electrode connector.

10. The multi-stage capacitively coupled plasma igniter according to claim 4, characterized in that: When D2 is 6 mm, a relationship curve between the electrode spacing and the radio frequency power is obtained, and a constraint condition for a dual-stage excitation plasma jet is constructed according to the plasma excitation state and the relationship curve; The expression of the relationship curve is: P=1.25D1 2 +0.5D1+115 Wherein, P represents the radio frequency power, D1 represents the electrode spacing, a is the coefficient of the quadratic term, b is the coefficient of the linear term, and c is the constant term; The constraints specifically include: When the excitation power exceeds the relationship curve, the plasma excitation state is excitation; When the excitation power is lower than the relationship curve, the plasma excitation state is not excited.

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