Device and method for regulating and controlling radial density of radio frequency capacitive coupling plasma

Abstract

The invention discloses a device and method for regulating and controlling the radial density of radio frequency capacitive coupling plasma, and relates to the technical field of semiconductor technologies, and the device comprises a capacitive coupling radio frequency discharge device and a coil. The coils comprise a first coil, a second coil and a third coil; for a non-high-frequency capacitive coupling plasma discharge working condition, the first coil is arranged above the plasma discharge chamber; for a high-frequency capacitive coupling plasma discharge working condition, the second coil is arranged above the plasma discharge chamber, and the third coil is arranged below the plasma discharge chamber; wherein the current on the second coil is opposite to the current on the third coil. And the radial density distribution uniformity of the plasma in the plasma discharge chamber can be optimized.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a device and method for regulating the radial density of radio frequency capacitively coupled plasma. Background Art

[0002] Low-pressure RF plasma applications include plasma etching, magnetron sputtering coating processes, etc., which widely use capacitively coupled plasma (CCP) sources. Under low-pressure, high-frequency capacitively coupled plasma discharge conditions, the existence of standing wave effects will lead to uneven radial distribution of plasma density, which is characterized by a significant density peak at the center of the reactor (plasma discharge chamber); while under high-pressure discharge conditions, due to edge effects, the plasma in the CCP chamber (plasma discharge chamber) usually shows an uneven distribution with lower center density and higher edge density. In recent years, semiconductor process technology has been developing towards small feature sizes, large-area wafers, and higher discharge frequencies and powers. The requirements for etching aspect ratios and process uniformity are constantly increasing. Uneven plasma density distribution will have an adverse effect on the product quality of the manufacturing process, bringing severe challenges to traditional CCP-based plasma technology.

[0003] In the process of low-temperature RF capacitively coupled plasma processing of wafers, the plasma density is concentrated in the center of the plasma discharge chamber or the edge of the wafer. Therefore, corresponding to different working conditions, there is often a problem of radial plasma density non-uniformity. The radial plasma density non-uniformity will cause a series of key problems, such as: the radial plasma density gradient will distort the sheath, thereby inducing a transverse electric field, resulting in an angle deflection of the plasma incident on the wafer, uneven process, etc. Therefore, the art urgently needs a method for regulating the radial density of RF capacitively coupled plasma, which is conducive to optimizing the uniformity of the radial density distribution of plasma. Summary of the invention

[0004] The purpose of the present invention is to provide a device and method for regulating the radial density of radio frequency capacitively coupled plasma, which is beneficial to optimizing the uniformity of the radial density distribution of plasma in a plasma discharge chamber.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] In a first aspect, a device for regulating radial density of radio frequency capacitively coupled plasma is provided, wherein the device comprises:

[0007] A capacitively coupled radio frequency discharge device and a coil; the coil comprises a first coil, a second coil and a third coil; the first coil is one or more groups of DC coils, and the second coil and the third coil are both a group of DC coils; the capacitively coupled radio frequency discharge device comprises a plasma discharge chamber;

[0008] For non-high-frequency capacitively coupled plasma discharge conditions, the first coil is arranged above the plasma discharge chamber;

[0009] For high-frequency capacitively coupled plasma discharge conditions, the second coil is arranged above the plasma discharge chamber, and the third coil is arranged above the plasma discharge chamber; wherein the current on the second coil and the current on the third coil are opposite currents.

[0010] In a second aspect, a method for regulating radial density of radio frequency capacitively coupled plasma is provided, which is applied to the device for regulating radial density of radio frequency capacitively coupled plasma according to any one of the first aspects, and the method comprises:

[0011] Obtaining plasma density distribution in the plasma discharge chamber;

[0012] According to the plasma density distribution, the setting position of the coil under different working conditions is determined, specifically including: wherein the different working conditions include non-high-frequency capacitively coupled plasma discharge conditions and high-frequency capacitively coupled plasma discharge conditions;

[0013] For non-high-frequency capacitively coupled plasma discharge conditions, the radial distribution of plasma density is adjusted by changing the current size of the first coil, the number of coil groups, the coil radius and the coil position to obtain the target plasma density distribution;

[0014] For high-frequency capacitively coupled plasma discharge conditions, the spatial magnetic field configuration is modulated by changing the current magnitude and coil radius of the second coil, as well as the current magnitude and coil radius of the third coil, to obtain the target plasma density distribution; the spatial magnetic field configuration includes the direction of the axial magnetic field component and the direction of the radial magnetic field component.

[0015] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0016] According to the present invention, a first coil is arranged above a plasma discharge chamber for non-high-frequency discharge conditions, and the local radial magnetic field distribution in the plasma discharge chamber is enhanced by changing the magnetic field strength and magnetic field direction of the position of the first coil, so that the plasma density near the first coil is increased, thereby improving the uniformity of the radial density distribution of the plasma as a whole; according to the present invention, a second coil is arranged above the plasma discharge chamber for high-frequency capacitively coupled plasma discharge conditions, and a third coil is arranged below the plasma discharge chamber, and reverse currents are set for the currents of the second coil and the third coil, and the magnetic field strength and magnetic field direction of the positions of the second coil and the third coil are changed, so that the radial magnetic field distribution in the plasma discharge chamber is enhanced, thereby suppressing the standing wave effect in the center of the plasma discharge chamber, reducing the plasma density in the central area of ​​the plasma discharge chamber, and greatly adjusting the uniformity of the radial density distribution of the plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A cross-sectional view of a device for regulating radial density of radio frequency capacitively coupled plasma under high frequency capacitively coupled plasma discharge conditions provided in Example 1 of the present invention;

[0019] Figure 2 A cross-sectional view of a device for controlling the radial density of radio frequency capacitively coupled plasma under non-high frequency capacitively coupled plasma discharge conditions provided in Example 1 of the present invention;

[0020] Figure 3 A schematic flow chart of a method for controlling the radial density of a radio frequency capacitively coupled plasma provided in Example 1 of the present invention;

[0021] Figure 4 It is a schematic diagram of plasma density under high-frequency capacitively coupled plasma discharge conditions; Figure 4 (a) is the plasma density distribution diagram of high-frequency capacitively coupled plasma without coil; Figure 4 (b) is the plasma density distribution diagram of the high-frequency capacitively coupled plasma working condition with a coil;

[0022] Figure 5 It is a schematic diagram of plasma density under non-high-frequency capacitively coupled plasma discharge conditions; Figure 5(a) is the plasma density distribution diagram of the non-high-frequency capacitively coupled plasma discharge condition without a coil; Figure 5 (b) is the plasma density distribution diagram of the non-high-frequency capacitively coupled plasma discharge condition with a coil. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The purpose of the present invention is to set a first coil above the plasma discharge chamber for non-high-frequency discharge conditions, and to enhance the local radial magnetic field distribution in the plasma discharge chamber by changing the magnetic field strength and magnetic field direction at the position of the first coil, so as to increase the plasma density near the first coil, thereby improving the uniformity of the radial density distribution of the plasma as a whole.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 As shown, the control device for the radial density of the radio frequency capacitively coupled plasma in this embodiment includes: a capacitively coupled radio frequency discharge device 1 and a coil; the coil includes a first coil 4, a second coil 2 and a third coil 3; the first coil 4 is one or more groups of DC coils, and the second coil 2 and the third coil 3 are both a group of DC coils; the capacitively coupled radio frequency discharge device 1 includes a plasma discharge chamber 5; for non-high-frequency capacitively coupled plasma discharge conditions, the first coil 4 is arranged above the plasma discharge chamber 5; for high-frequency capacitively coupled plasma discharge conditions, the second coil 2 is arranged above the plasma discharge chamber, and the third coil 3 is arranged below the plasma discharge chamber; wherein the current on the second coil 2 and the current on the third coil 3 are opposite currents.

[0027] In practical applications, the above-mentioned device does not need to change the complex chamber structure. It only needs to apply additional different DC coil combinations above and below the chamber to achieve a more uniform radial plasma density distribution and a more collimated incident ion angle distribution on the lower electrode surface for the plasma chamber or large-area plasma discharge chamber.

[0028] In some embodiments, the coil is disposed outside the capacitively coupled discharge device 1 ; the diameter of the coil is less than or equal to the diameter of the plasma discharge chamber 5 .

[0029] like Figure 1 A set of DC coils, namely the second coil 2 and the third coil 3, are respectively arranged above and below the plasma discharge chamber to control the direction of the generated magnetic flux lines to point to the discharge chamber, which can effectively suppress the central standing wave effect of the high-frequency plasma discharge chamber.

[0030] In some embodiments, the group of DC coils is a plurality of turns of circular conductive wires connected to each other; the plurality of groups of DC coils include at least one group of DC coils.

[0031] like Figure 2 A first coil 4 is arranged above the plasma discharge chamber. The first coil 4 is one or more groups of DC coils (the number of groups can be flexibly adjusted). If there are multiple groups of DC coils, the coils need to be coaxially arranged. There is a significant radial component in the magnetic field in the plasma discharge chamber below the position of the first coil 4, which constrains the axial cyclotron motion of the plasma to reduce the loss on the electrode, significantly improves the plasma density near the coil radius, and can effectively suppress the edge plasma density peak under non-high-frequency capacitively coupled plasma discharge conditions.

[0032] By adjusting the position, number of groups, radius of the applied coils, number of turns and current of different groups of coils, the spatial distribution of the static magnetic field in the chamber can be modulated to produce a transport effect on the plasma, thereby improving the radial distribution of the plasma density, which is particularly beneficial for optimizing the uniformity of radial plasma distribution in large-area chamber discharges and improving the collimation of the incident ion angle above the wafer. This is crucial for plasma processing.

[0033] Specifically, the capacitively coupled radio frequency discharge device is used in chip etching or deposition processes, and the device also includes a wafer 6 , which is located directly below the plasma discharge chamber 5 .

[0034] The capacitively coupled radio frequency discharge device 1 further comprises a radio frequency source, which excites the plasma chamber in a capacitively coupled manner through a matching network to generate capacitively coupled plasma.

[0035] The capacitively coupled RF discharge device 1 further includes a focusing ring 7 , which is disposed on the outside of the wafer 6 . The focusing ring 7 can extend the wafer surface to converge the plasma, thereby improving the uniformity of etching of the wafer 6 .

[0036] In some embodiments, the frequency of the high-frequency capacitively coupled plasma in the non-high-frequency capacitively coupled plasma discharge condition is less than 60 MHz; the frequency of the high-frequency capacitively coupled plasma in the high-frequency capacitively coupled plasma discharge condition is greater than or equal to 60 MHz.

[0037] In practical applications, for high-frequency (≥60MHz) discharge, a group of coaxial reverse DC coils are applied on the upper and lower sides of the plasma chamber 5 respectively, and the axial magnetic field components generated are in opposite directions, thereby canceling or weakening the directions of the axial magnetic field components; while the radial magnetic field components are in the same direction to enhance the bound plasma, which not only enhances the plasma density at the edge of the plasma chamber 5, but also produces an effect of transporting the plasma at the center of the plasma chamber 5 outward, thereby suppressing the standing wave effect in the center of the plasma chamber 5 as a whole and improving the overall density uniformity.

[0038] Among them, for non-high frequency (<60MHz) capacitively coupled plasma discharge conditions, one or more groups of DC coils (coil diameter ≤ chamber diameter) are arranged above the plasma discharge chamber 5, and the diameter of the coil and the distance from the chamber can be flexibly adjusted. The radial distribution of the plasma density can be adjusted by changing the size of the DC current.

[0039] Among them, for high-frequency (≥60MHz) capacitively coupled plasma discharge conditions, a group of DC coils are respectively arranged above and below the plasma discharge chamber 5 (that is, the two groups of coils are respectively located above and below the chamber, and the diameters of the two groups of coils can be adjusted independently and flexibly, but the currents are reverse currents). Changing the current size will modulate the spatial magnetic field configuration, especially weakening the longitudinal magnetic field component and increasing the transverse magnetic field component, thereby flexibly improving the radial density distribution of the plasma and the angle of ion bombardment of the electrode plate.

[0040] Reference Figure 3 , a method for regulating the radial density of radio frequency capacitively coupled plasma is provided, using the above-mentioned device for regulating the radial density of radio frequency capacitively coupled plasma, characterized in that the method comprises:

[0041] Step 11: Obtain the plasma density distribution in the plasma discharge chamber.

[0042] The plasma density distribution is obtained to determine the specific location where the plasma density is sparse or uneven.

[0043] Step 12: Determine the setting position of the coil under different working conditions according to the plasma density distribution, specifically including: wherein the different working conditions include non-high-frequency capacitively coupled plasma discharge conditions and high-frequency capacitively coupled plasma discharge conditions.

[0044] Step 13: For non-high-frequency capacitively coupled plasma discharge conditions, the radial distribution of plasma density is adjusted by changing the current of the first coil, the number of coil groups, the coil radius and the coil position to obtain the target plasma density distribution.

[0045] Among them, the target plasma density distribution is that the density in the horizontal direction of the plasma chamber is almost equal (fluctuation within 20%). The specific process is that the magnetic field below the coil is stronger, which will enhance local discharge. Therefore, placing the coil near the position with lower density can improve the overall uniformity.

[0046] In practical applications, refer to Figure 5 In (a), it can be seen that when there is no coil, there is a significant plasma density peak at the edge of the plasma discharge chamber; Figure 5 In (b), the first coil 4 applied above the chamber includes three groups of DC coils, so that the plasma density in the plasma discharge chamber 4 below the position of the first coil 4 is increased, and the overall radial plasma density uniformity is significantly improved.

[0047] In some embodiments, for non-high-frequency capacitively coupled plasma discharge conditions, the radial distribution of plasma density is adjusted by changing the current size, the number of coil groups, the coil radius and the coil position of the first coil to obtain a first plasma density distribution, specifically including: determining the correspondence between the direction of the axial magnetic field component and the direction of the radial magnetic field component by changing the current size, the number of coil groups, the coil radius and the coil position of the first coil; according to the correspondence between the direction of the axial magnetic field component and the direction of the radial magnetic field component, adjusting the radial distribution of plasma density to obtain a target plasma density distribution.

[0048] In some embodiments, under non-high-frequency capacitively coupled plasma discharge conditions, based on the right-hand screw rule and the current direction of the first coil, the radial magnetic field components in the spatial magnetic field excited by the first coil are made to have the same direction.

[0049] In practical applications, under non-high-frequency capacitively coupled plasma discharge conditions, when one or more groups of DC coils are arranged at different positions above the plasma chamber, the magnetic field distribution in the plasma discharge chamber below the radial position of each group of DC coils produces a significant radial component, thereby constraining the axial cyclotron motion of the plasma to reduce the loss on the electrode and significantly increase the plasma density near the coil.

[0050] It is worth noting that the magnetic field strength at the positions corresponding to different DC coil radii in the plasma discharge chamber 5 is regulated according to different combinations of the number of groups, radius, current, number of turns and quantity of the DC coils to obtain a more uniform radial plasma density distribution, thereby achieving a more collimated angle distribution of incident ions on the wafer surface.

[0051] Step 14: For high-frequency capacitively coupled plasma discharge conditions, the spatial magnetic field configuration is modulated by changing the current magnitude and coil radius of the second coil 2, as well as the current magnitude and coil radius of the third coil 3, to obtain the target plasma density distribution; the spatial magnetic field configuration includes the direction of the axial magnetic field component and the direction of the radial magnetic field component.

[0052] Among them, high-frequency discharge usually leads to a higher density at the center of the plasma chamber. By setting the second coil 2 and the third coil 3, the magnetic field configuration can be modulated so that the plasma diffuses and migrates from the high-density area to the low-density area in the horizontal direction, so as to improve the overall uniformity.

[0053] In practical applications, such as Figure 4 In (a), it can be seen that when there is no coil, under the high-frequency capacitively coupled plasma discharge condition, the plasma density is concentrated at the center due to the standing wave effect; Figure 4 In (b), it can be seen that by applying a group of DC coils above the plasma extraction chamber 5 and a group of DC coils below, the standing wave effect in the center of the chamber is suppressed, the plasma density at the center is reduced, the plasma density at the edge is increased, and the radial uniformity of the plasma density distribution can be greatly adjusted.

[0054] In some embodiments, based on the right-hand screw rule and opposite currents on the second coil and the third coil, the direction of the axial magnetic field component in the spatial magnetic field excited by the second coil is modulated to be opposite to the direction of the axial magnetic field component in the spatial magnetic field excited by the third coil, and the direction of the radial magnetic field component in the spatial magnetic field excited by the second coil is the same as the direction of the radial magnetic field component in the spatial magnetic field excited by the third coil.

[0055] In practical applications, based on the right-hand screw rule, the opposite currents on the second coil 2 and the third coil 3 make the directions of the axial magnetic field components opposite, so that the axial magnetic field components cancel each other out or weaken each other, while the directions of the radial magnetic field components are the same, so that the radial magnetic field components are superimposed and enhanced. That is, the longitudinal magnetic field component is weakened, and the transverse magnetic field component is increased, thereby flexibly improving the radial density distribution of the plasma and the angle of ion bombardment of the plate. In this way, on the one hand, the magnetic lines of force can transport the higher plasma density at the center of the plasma discharge chamber outward, which can effectively weaken the plasma density peak caused by the standing wave effect in the center of the chamber; on the other hand, the direction of the radial magnetic field component can reduce the loss of plasma on the electrode, especially at the edge of the plasma chamber where the radial magnetic field component is the strongest, which can significantly increase the plasma density at the edge.

[0056] In practical applications, the number of DC coil groups can be flexibly adjusted. According to different combinations of the number of coil groups, number of turns, radius, and current size, the axial and radial components of the magnetic field applied to the plasma chamber can be flexibly controlled to obtain a better plasma discharge effect without changing other conditions.

[0057] It is worth mentioning that the present invention proposes to induce a radially symmetric static magnetic field inside the chamber to reduce the electron trajectory by arranging coaxial coils above and below the plasma chamber and adjusting the number of coil groups, number of turns, radius, current, etc., thereby flexibly controlling the radial uniformity of the plasma and a more collimated angle distribution of incident ions, which will play a very critical role in the application of low-pressure RF plasma and the development of semiconductor process technology.

[0058] The present invention is aimed at high-frequency capacitively coupled plasma discharge conditions. A group of DC coils are respectively arranged above and below the plasma discharge chamber 5. The diameters of the two groups of DC coils can be adjusted independently and flexibly. However, the current is a reverse current. Changing the current size will modulate the spatial magnetic field configuration, especially weakening the longitudinal magnetic field component and increasing the transverse magnetic field component, thereby enhancing the radial magnetic field distribution in the plasma discharge chamber, thereby suppressing the standing wave effect in the center of the plasma discharge chamber, reducing the plasma density in the central area, and greatly adjusting the uniformity of the radial density distribution of the plasma.

[0059] For non-high-frequency capacitively coupled plasma discharge conditions, one or more groups of DC coils are arranged above the plasma discharge chamber 5. By flexibly adjusting the number of coil groups, radius, current, number of turns and quantity, as well as the distance from the chamber, etc., the plasma density near the radial position of the applied DC coil is increased, thereby solving the problem of uneven radial density distribution of plasma caused by edge effect.

[0060] It should be noted that the object information (including but not limited to object device information, object personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in the present invention are all information and data authorized by the object or fully authorized by all parties.

[0061] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magneto resistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided by the present invention may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited thereto. The processor involved in each embodiment provided by the present invention may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited thereto.

[0062] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A device for controlling radial density of radio frequency capacitively coupled plasma, characterized in that: The device comprises: A capacitively coupled radio frequency discharge device and a coil; the coil comprises a first coil, a second coil and a third coil; the first coil is one or more groups of DC coils, and the second coil and the third coil are both a group of DC coils; the capacitively coupled radio frequency discharge device comprises a plasma discharge chamber; For non-high-frequency capacitively coupled plasma discharge conditions, the first coil is arranged above the plasma discharge chamber; For high-frequency capacitively coupled plasma discharge conditions, the second coil is arranged above the plasma discharge chamber, and the third coil is arranged below the plasma discharge chamber; wherein the current on the second coil and the current on the third coil are opposite currents.

2. The device for controlling the radial density of radio frequency capacitively coupled plasma according to claim 1, characterized in that: The coil is arranged outside the capacitive coupling discharge device; the diameter of the coil is smaller than or equal to the diameter of the plasma discharge chamber.

3. The device for controlling the radial density of radio frequency capacitively coupled plasma according to claim 1, characterized in that: The group of DC coils is a plurality of turns of circular conductive wires connected to each other; the plurality of groups of DC coils at least include the group of DC coils.

4. The method for controlling the radial density of radio frequency plasma according to claim 1, characterized in that: The capacitively coupled radio frequency discharge device further includes a wafer, and the wafer is located directly below the plasma discharge chamber.

5. The method for controlling the radial density of radio frequency plasma according to claim 1, characterized in that: The frequency of the high-frequency capacitively coupled plasma in the non-high-frequency capacitively coupled plasma discharge condition is less than 60 MHz; the frequency of the high-frequency capacitively coupled plasma in the high-frequency capacitively coupled plasma discharge condition is greater than or equal to 60 MHz.

6. A method for controlling the radial density of a radio frequency capacitively coupled plasma, applied to the device for controlling the radial density of a radio frequency capacitively coupled plasma according to any one of claims 1 to 5, characterized in that: The method comprises: Obtaining plasma density distribution in the plasma discharge chamber; According to the plasma density distribution, the setting position of the coil under different working conditions is determined, specifically including: wherein the different working conditions include non-high-frequency capacitively coupled plasma discharge conditions and high-frequency capacitively coupled plasma discharge conditions; For non-high-frequency capacitively coupled plasma discharge conditions, the radial distribution of plasma density is adjusted by changing the current size, coil group number, coil radius and coil position of the first coil to obtain the target plasma density distribution; For high-frequency capacitively coupled plasma discharge conditions, the spatial magnetic field configuration is modulated by changing the current magnitude and coil radius of the second coil, as well as the current magnitude and coil radius of the third coil, to obtain the target plasma density distribution; the spatial magnetic field configuration includes the direction of the axial magnetic field component and the direction of the radial magnetic field component.

7. The method for controlling the radial density of radio frequency plasma according to claim 6, characterized in that: For non-high-frequency capacitively coupled plasma discharge conditions, the radial distribution of plasma density is adjusted by changing the current size, coil group number, coil radius and coil position of the first coil to obtain the target plasma density distribution, specifically including: By changing the current magnitude, the number of coil groups, the coil radius and the coil position of the first coil, the corresponding relationship between the direction of the axial magnetic field component and the direction of the radial magnetic field component is determined; According to the corresponding relationship between the direction of the axial magnetic field component and the direction of the radial magnetic field component, the radial distribution of the plasma density is adjusted to obtain the target plasma density distribution.

8. The method for controlling the radial density of radio frequency plasma according to claim 6, characterized in that: For high-frequency capacitively coupled plasma discharge conditions, the spatial magnetic field configuration is modulated by changing the current magnitude and coil radius of the second coil, and the current magnitude and coil radius of the third coil, specifically including: Based on the right-hand screw rule and opposite currents on the second coil and the third coil, the direction of the axial magnetic field component in the spatial magnetic field excited by the second coil is modulated to be opposite to the direction of the axial magnetic field component in the spatial magnetic field excited by the third coil, and the direction of the radial magnetic field component in the spatial magnetic field excited by the second coil is the same as the direction of the radial magnetic field component in the spatial magnetic field excited by the third coil.

9. The method for controlling the radial density of radio frequency plasma according to claim 6, characterized in that: include: Under non-high-frequency capacitively coupled plasma discharge conditions, based on the right-hand screw rule and the current direction of the first coil, the radial magnetic field components in the spatial magnetic field excited by the first coil are made to have the same direction.

10. The method for controlling the radial density of radio frequency plasma according to claim 1, characterized in that: The coil is coaxially arranged with the plasma discharge chamber.

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