Faraday shield structure and ion source

Abstract

The application relates to the technical field of ion sources, and provides a Faraday shielding structure and an ion source. The Faraday shielding structure is arranged close to a discharge chamber and is used for shielding plasma. The Faraday shielding structure comprises a plurality of same shielding units which are connected in a head-to-tail mode along the circumference of the inner wall of the discharge chamber. Any shielding unit comprises a plurality of continuous and connected curved side walls, so that a shielding channel is defined between adjacent shielding units based on the side walls and is used for gradually reducing the reflection angle of the plasma entering the shielding channel. The application has the advantages of improving sharp corner sputtering and ensuring the screen protection effect.

Description

Technical Field

[0001] This application relates to the field of ion source technology, and more specifically, to a Faraday shielding structure and an ion source. Background Technology

[0002] An ion source is a device that ionizes neutral atoms or molecules and extracts an ion beam from them. Ion sources are indispensable components of various types of ion accelerators, mass spectrometers, electromagnetic isotope separators, ion implanters, ion beam etching devices, and other equipment.

[0003] In existing technologies, to improve the coupling efficiency of ion sources, prevent plasma from bombarding the inner wall of the discharge chamber, and stabilize the plasma sheath and density distribution, a Faraday shielding structure is often installed on the inner wall of the discharge chamber near the ion source. Faraday shielding structures include: straight-cylinder slotted structures, inclined slotted structures, and polygonal structures. Straight-cylinder slotted structures are the easiest to manufacture, but their shielding capability is insufficient; inclined slotted structures improve the shielding effect through inclined slots, but require consideration of electromagnetic coupling and manufacturing feasibility; polygonal structures, because their polygonal channels can block the linear motion of plasma, theoretically have the best shielding effect, but they suffer from sharp corners, burrs, and surface defects, resulting in severe ion sputtering and easily inducing local electric field enhancement, leading to shield failure. Therefore, there is an urgent need in existing technologies for a Faraday shielding structure that can both improve sharp-corner sputtering and ensure shielding effectiveness. Summary of the Invention

[0004] This application addresses the shortcomings of existing methods by proposing a Faraday shielding structure and ion source to solve the technical problem that related technologies cannot simultaneously improve sharp-corner sputtering and ensure shielding effectiveness.

[0005] In the first aspect, embodiments of this application provide a Faraday shielding structure, disposed close to a discharge chamber, for shielding plasma, comprising: a plurality of identical shielding units arranged end to end along the circumference of the inner wall of the discharge chamber; Each of the shielding units includes a plurality of continuously connected curved sidewalls, such that a shielding channel is defined between adjacent shielding units based on the sidewalls, for gradually reducing the reflection angle of plasma entering the shielding channel.

[0006] Specifically, the main technical concept of this application embodiment lies in solving the technical problem of sharp corners on the surface of the shielding unit by using several continuously connected curved sidewalls, which greatly avoids sharp corner sputtering caused by plasma impacting the sharp corners of the shielding unit. Simultaneously, the shielding channels defined between the sidewalls of adjacent shielding units are used to gradually reduce the reflection angle of the incoming plasma, thereby increasing the number of reflections of the plasma between the shielding channels. Through multiple reflections of the plasma, the kinetic energy carried by the plasma is gradually reduced, thereby improving the shielding effect of this application embodiment. Therefore, this application embodiment has the advantages of both improving sharp corner sputtering and ensuring shielding effectiveness.

[0007] Furthermore, the shielding unit is configured to extend axially along the discharge chamber based on a customized cross-section.

[0008] Furthermore, the shielding channel is divided into a first channel segment, a second channel segment, and a third channel segment in sequence based on the direction of plasma propagation; The first channel segment is used to shield plasma with an incident angle smaller than a preset radial angle; The second channel segment is used to reflect the plasma at least once; The third channel segment is used to guide the plasma to exit in a direction away from the inner wall of the discharge chamber.

[0009] Specifically, another technical concept of this application embodiment is that, through the three-section design of the shielding channel, the plasma of the incident and outgoing shielding channels is screened, which greatly reduces the plasma throughput of the shielding channel, and makes the plasma that passes through the shielding channel undergo multiple reflections to greatly reduce the kinetic energy carried by the plasma, so that the outgoing plasma is difficult to effectively impact the inner wall of the discharge chamber, thereby further optimizing the shielding effect provided by this application embodiment.

[0010] Furthermore, the preset radial angle ranges from 60° to 90°.

[0011] Optionally, the curvature of the sidewall corresponding to the second channel segment is greater than the curvature of the sidewall corresponding to the first channel segment and the third channel segment, so that the shielding channel bends in the second channel segment.

[0012] Optionally, the width of the shielding channel narrows from the second channel segment toward the first channel segment and the third channel segment, respectively.

[0013] Optionally, the outer contour of the cross-section is configured as a Bézier curve, a B-spline curve, or a non-uniform B-spline, including: The transition point between the first channel segment, the second channel segment, and the third channel segment is defined as the first node and the second node; Based on the first node and the second node, the outer contour is divided into a first parameter curve, a second parameter curve, and a third parameter curve; Based on the plasma processing requirements of the first channel segment, the second channel segment, and the third channel segment, the first parameter curve, the second parameter curve, and the third parameter curve are confirmed.

[0014] Furthermore, the outer contour also includes: The first pass rate and the second pass rate of plasma escaping the shielding channel through one reflection and two reflections are obtained respectively for different combinations of the first parameter curve, the second parameter curve and the third parameter curve; The first pass rate and / or second pass rate are filtered to obtain a combination of the first parameter curve, the second parameter curve and the third parameter curve that meet the preset pass rate.

[0015] Specifically, another technical concept of this application embodiment is that by screening the plasma first pass rate and / or second pass rate, the final obtained outer contour can minimize the proportion of plasma passing through the emission shielding channel through a limited number of reflections, so that the plasma in the emission shielding channel is basically reflected twice or more, thereby significantly reducing the kinetic energy carried by the plasma in the emission shielding channel, avoiding high kinetic energy plasma from bombarding the inner wall of the discharge chamber, and improving the service life of the discharge chamber.

[0016] In some optional implementations, the circumferential angle of the shielding unit is determined based on the erosion peak value of the inner wall of the discharge chamber, including: Based on the circumferential arrangement angles of multiple consecutive values, obtain the corresponding multiple different shielding units; Based on the erosion peak values ​​of multiple different shielding units under the same operating conditions, obtain the relationship curve between the circumferential layout angle and the erosion peak value; Based on the relationship curve, obtain the circumferential layout angle corresponding to the minimum erosion peak value.

[0017] Secondly, embodiments of this application provide an ion source, including: a discharge chamber, a coil assembly disposed around the outer wall of the discharge chamber, and a Faraday shielding assembly disposed near the inner wall of the discharge chamber, wherein the Faraday shielding assembly adopts the Faraday shielding structure according to any one of the first aspects.

[0018] It is understood that the technical effects of any optional embodiment of the second aspect provided in this application can be understood by referring to the technical effects of any optional embodiment of the first aspect.

[0019] The beneficial technical effects of the technical solutions provided in this application include: During the operation of the ion source, a large amount of moving plasma exists in the center of the discharge chamber. When the plasma impacts the shielding unit, the impact point is a smooth, continuous curved surface due to the shielding unit's continuous sidewalls. This prevents sharp-angle sputtering from occurring when the plasma impacts the shielding unit, significantly improving the shielding performance and avoiding shielding failure caused by enhanced electric field due to plasma sputtering. This enhances the reliability and stability of the Faraday shielding structure provided in this embodiment. Furthermore, after entering the shielding channel, the plasma's reflection angle gradually decreases, ensuring multiple reflections within the channel, thus improving the shielding effect. Additionally, the multiple impacts and reflections within the shielding channel significantly reduce the kinetic energy carried by the plasma exiting the channel. Even if the plasma impacts the inner wall of the discharge chamber, the low kinetic energy prevents effective sputtering, further improving the shielding effect and extending the service life of the discharge chamber. Therefore, the Faraday shielding structure provided in this application has the advantages of improving plasma sharp-angle sputtering and ensuring shielding effect, thereby improving the service life of the discharge chamber and the stability of the ion source during long-term operation.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of an ion source provided in an embodiment of this application; Figure 2 The hidden features provided for the embodiments of this application Figure 1 Schematic diagram of the structure of the central grid; Figure 3 This is a schematic diagram of a Faraday shielding structure provided in an embodiment of this application; Figure 4 Provided for the embodiments of this application Figure 3 A schematic diagram of the structure of the shielding unit in the middle; Figure 5 Provided for the embodiments of this application Figure 3 A top-down view; Figure 6 A schematic diagram of the structure of the shielding channel defined by two adjacent shielding units provided in an embodiment of this application; Figure 7 A schematic diagram of the plasma incident shielding channel provided in the embodiments of this application; Figure 8 A schematic diagram illustrating the process of plasma impact and reflection in a shielded channel, provided in an embodiment of this application; Figure 9 This is a schematic diagram of the plasma emission shielding channel provided in the embodiments of this application; Figure label: 1. Grid; 2. Discharge chamber; 3. Coil assembly; 4. Base plate; 5. Air inlet; 6. Faraday shielding structure; 7. Plasma; 21. Inner wall; 22. Outer wall; 61. Shielding unit; 62. Shielding channel; 611. Outer contour; 621. First channel segment; 622. Second channel segment; 623. Third channel segment; 611a. First node; 611b. Second node. Detailed Implementation The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0022] Those skilled in the art will understand that, unless specifically stated otherwise, the terms "described" and "the" as used herein may also include plural forms. It should be further understood that the term "comprising" as used in the specification of this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude other features, information, data, steps, operations, elements, components, and / or combinations thereof supported by the art. The term "and / or" as used herein refers to at least one of the items defined by the term; for example, "A and / or B" can be implemented as "A," or as "B," or as "A and B."

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0024] The research and development approach of this application includes: based on the "channel-type" Faraday shielding unit, improving the Faraday shielding structure to enhance the shielding capability of the Faraday shielding unit without significantly affecting the ion source coupling efficiency and power loss. Specifically, the sidewalls of the Faraday shielding unit are designed such that each sidewall comprises several continuously connected curved surfaces. This ensures that any impact of plasma on any point of the shielding unit is a curved surface impact, greatly reducing the impact of plasma on sharp corners of the shielding unit and avoiding shielding failure caused by enhanced electric field due to secondary sputtering, thus improving the operational stability of the Faraday shielding structure. In another aspect, the structure of the sidewalls of the continuously connected curved surfaces in this application is optimized so that the reflection angle of the plasma after entering the shielding channel ("channel") gradually decreases, thereby increasing the number of reflections of the plasma in the shielding channel, improving the physical barrier effect of the shielding channel on the plasma, and even if the plasma exits from the shielding channel after multiple reflections, the kinetic energy carried by the plasma will be greatly reduced due to multiple impacts, making it difficult to form effective sputtering on the inner wall of the discharge chamber, thereby ensuring the shielding effect of this application embodiment and improving the service life of the discharge chamber.

[0025] Understandably, related technologies have investigated the performance of Faraday shielding structures with slotted structures (channels). Specifically, these technologies have tested the coupling efficiency, power loss ratio, and shielding effect of several different types of slotted Faraday shielding structures, primarily involving oblique slots and Z-shaped barriers. The experiments revealed that the coupling efficiency and power loss ratio of different types of slotted Faraday shielding structures are not significantly different, generally around 1%-2%. However, the shielding effect varies considerably depending on the angle, type, and construction of the slots. The technologies found that straight-through slotted structures have the worst shielding effect, while Z-shaped slotted structures, due to their barrier construction, offer the best shielding effect. The advantage of the Z-shaped slotted structure lies in the fact that the channels formed by the slots are mutually interlocking and barrier-like, thus improving the plasma shielding effect by completely preventing plasma from flowing straight through the channels. Meanwhile, based on experimental results from related technologies, this application embodiment found that although related technologies have verified that channel-type or slit-type Faraday shielding structures can ensure the coupling efficiency and power loss ratio of ion sources, and the shielding effect of Z-shaped slotted structures is indeed quite ideal, the shielding channels of Z-shaped slotted structures have multiple right-angle bends inside. Furthermore, repeated verification in this application embodiment revealed that the sharp corners and burrs inside the shielding channels make it extremely easy for plasma to generate secondary sputtering when impacting right-angle bends, thereby causing an enhancement of the electric field inside the shielding channel and inducing shielding failure. In particular, for ion sources operating at high voltage for extended periods, the electric field enhancement caused by sharp-corner sputtering is more pronounced. Therefore, although the Z-shaped slotted structure provided by related technologies has excellent shielding effects, its stability and high-voltage applicability are poor, making it difficult to apply to ion sources operating at high voltage for extended periods. Additionally, "channel-type" Faraday shielding structures (also known as "slit-type" Faraday shielding structures) are a general term for Faraday shielding structures with shielding channels, referring to Faraday shielding structures where plasma can pass through channels between shielding units.

[0026] This application provides a Faraday shielding structure and an ion source, which aims to solve the above-mentioned technical problems in related technologies.

[0027] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. It should be noted that the following embodiments can be referenced, learned from, or combined with each other, and the same terms, similar features, and similar implementation steps in different embodiments will not be described again.

[0028] To explain the application scenarios of the embodiments of this application, please refer to... Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of an ion source provided in an embodiment of this application. Figure 2The hidden features provided for the embodiments of this application Figure 1 A schematic diagram of the structure of the central grid 1.

[0029] This application provides an ion source, including: a discharge chamber 2, a coil assembly 3, a Faraday shielding structure 6, a grid 1, a base plate 4, and an air inlet 5.

[0030] The discharge chamber 2, configured as a cylindrical structure, is typically made of insulating, high-temperature resistant, and sputter-resistant materials such as quartz and alumina. It serves to provide a sealed space for gas ionization, generating plasma 7. Understandably, the Faraday shielding structure 6 prevents the plasma 7 from sputtering onto the inner wall 21 of the discharge chamber 2 while ensuring the coupling efficiency of the coil assembly 3, thus improving the service life of the discharge chamber 2.

[0031] The coil assembly 3 is arranged around the outer wall 22 of the discharge chamber 2 to generate a coupling magnetic field to accelerate the ionization of the gas in the discharge chamber 2.

[0032] The Faraday shielding structure 6 is disposed close to the inner wall 21 of the discharge chamber 2, thereby isolating the inner wall 21 of the discharge chamber 2 from the plasma 7 generated within the discharge chamber 2, and shielding the inner wall 21 of the discharge chamber 2 from sputtering by the plasma 7. Simultaneously, the Faraday shielding structure 6 must also avoid affecting the coupling efficiency of the coil assembly 3. It is understood that related technologies indicate that structural variations of the "channel-type" Faraday shielding structure 6 have minimal impact on the coupling efficiency and power loss ratio of the coil assembly 3; that is, the Faraday shielding structure 6 provided in this embodiment has good coupling efficiency and power loss ratio.

[0033] The grid 1 refers to the extraction grid structure of plasma 7, which is set at the extraction end of the discharge chamber 2 and configured as a porous plate structure for controlling the state of plasma 7 extracted from the discharge chamber 2.

[0034] The base plate 4 is located at the air inlet end of the discharge chamber 2, relative to the grid 1, and is used to seal the discharge chamber 2.

[0035] The air inlet 5 is located in the middle of the base plate 4 and is used to introduce ionized working gas, such as Ar, He, Ne, N2, etc.

[0036] It is understood that, although the embodiments of this application refer to Figure 1 and Figure 2 Taking a radio frequency ion source as an example, the structural composition of the ion source provided in this application embodiment and the installation position of the Faraday shielding structure 6 are shown. However, the Faraday shielding structure 6 provided in this application embodiment can also be applied to other application scenarios that require shielding.

[0037] Further, please refer to Figures 3 to 5 , Figure 3 This is a schematic diagram of a Faraday shielding structure 6 provided in an embodiment of this application. Figure 4 Provided for the embodiments of this application Figure 3 A schematic diagram of the structure of the shielding unit 61. Figure 5 Provided for the embodiments of this application Figure 3 A top-down view.

[0038] The Faraday shielding structure 6 provided in this embodiment includes multiple identical shielding units 61 arranged end-to-end along the circumference of the inner wall 21 of the discharge chamber 2. The multiple shielding units are arranged in a ring shape in space. The number of shielding units 61 is determined by the circumferential arrangement angle α indicated by the dotted line in the figure. For example, the number of shielding units 61 in a cylindrical discharge chamber 2 is 360° / α. Assuming α = 8°, the number of shielding units 61 is 360° / 8° = 45. Please refer to [reference needed]. Figure 5 It is understood that the number of shielding units 61 in the Faraday shielding structure 6 provided in this application embodiment can also be 30, 60, 90, 100, etc. Meanwhile, the Faraday shielding structure 6 provided in this application embodiment can also be used for irregularly shaped discharge chambers 2 by adapting the shielding units 61 to the inner wall of the discharge chamber 2.

[0039] The shielding unit 61 includes a plurality of continuously connected curved sidewalls, such that a shielding channel 62 is defined between adjacent shielding units based on the sidewalls. The plurality of continuously connected curved sidewalls refer to the sidewalls being configured with continuously transitioning curved surfaces in the circumferential direction, that is, any point on the sidewall is a transition point. Regardless of whether the plasma 7 impacts the sidewall from the center of the discharge chamber 2 or from inside the shielding channel 62, the impact relationship between the plasma 7 and the sidewall is a curved surface impact. That is, the shielding unit 61 provided in this application embodiment can effectively improve the sharp-corner sputtering of plasma 7, reduce the risk of shielding failure caused by the enhanced electric field of the Faraday shielding structure 6 due to sharp-corner sputtering, and improve the stability and reliability of the ion source's high-voltage long-term operation.

[0040] Optionally, the shielding unit is configured to extend along the axis of discharge chamber 2 based on a customized cross-section, please refer to Figure 4Specifically, the shielding unit 61 is configured as a columnar structure with several continuously connected curved sidewalls, oriented in a direction coinciding with the axis of the discharge chamber 2. Based on the structure of the shielding unit 61, the Faraday shielding structure 6 provided in this application can be integrally formed on the base plate 4 by 3D printing, and the sidewalls of each shielding unit 61 are polished to improve the smoothness of the sidewalls, thereby further suppressing sharp-angle sputtering when plasma 7 impacts the sidewalls. It is understood that the shielding channel provided in this application embodiment serves to gradually reduce the reflection angle of plasma 7. Theoretically, a twisted columnar structure can also achieve the technical effect provided in this application embodiment, but the processing of a twisted columnar structure is more difficult, while a straight columnar structure is easier to process by 3D printing.

[0041] In some alternative embodiments, please refer to Figure 6 This is a schematic diagram of the structure of a shielding channel 62 defined by two adjacent shielding units 61 provided in an embodiment of this application. The shielding channel 62 is sequentially divided into a first channel segment 621, a second channel segment 622, and a third channel segment 623 based on the direction of plasma 7. Please refer to [reference needed]. Figure 6 The dashed line indicates the division of the interval.

[0042] The first channel segment 621 is used to shield plasma 7 with an incident angle smaller than a preset radial angle. Please refer to... Figure 7 This is a schematic diagram of the plasma 7 incident shielding channel 62 provided in this application embodiment. The first channel segment 621 provided in this application embodiment is the entrance for plasma 7 defined between the outer wall 22 of one shielding unit 61 and the outer wall 22 of another adjacent shielding unit 61, and the incident angle of plasma 7 is limited by a preset radial angle. Specifically, the sidewalls of one shielding unit 61, depending on their relative states with the discharge chamber 2, plasma 7, and another shielding unit 61, include: an exposed sidewall facing the middle of the discharge chamber 2, a shielding channel 62 sidewall facing the other shielding unit 61, and a chamber sidewall facing the inner wall 21 of the discharge chamber 2. After contacting the exposed sidewall, the plasma 7 in the discharge chamber 2 is basically reflected back to the middle of the discharge chamber 2 by the exposed sidewall. After contacting the shielding channel 62 sidewall, some of the plasma 7 will enter the shielding channel 62 by reflection from the shielding channel 62 sidewall. Therefore, the lower the proportion of plasma 7 entering the shielding channel 62 through the shielding channel 62 sidewall, the better the shielding effect of the Faraday shielding structure 6 provided in this application embodiment. That is, the preset radial angle provided in this application embodiment is used to reduce the proportion of plasma 7 entering the shielding channel 62, for example: Figure 7 The angle between the tangent of the curved surface at a point on the entrance sidewall of the shielding channel 62 of the lower shielding unit 61 and the radius of that point and the radius of the annular distribution center of the shielding unit 61 (usually coinciding with the axial center of the discharge chamber 2) is a radial angle β1. Similarly, Figure 7 The angle between the tangent of a point on the inlet sidewall of the shielding channel 62 of the upper shielding unit 61 and the radius of that point and the center of the annular distribution circle of the shielding unit 61 is another radial angle β2. Therefore, the preset radial angle provided in this embodiment ranges from β1 to β2. When the incident radial angle of the plasma 7 is less than β1 or greater than β2, it will be reflected back to the center of the discharge chamber 2 by the exposed sidewall of the shielding unit 61. Only when the incident angle of the plasma 7 is between β1 and β2 can it enter the shielding channel 62. Please refer to... Figure 7 The solid arrow in the middle illustrates that, in this embodiment of the application, by setting a preset radial angle at the entrance of the first channel segment 621, only plasma 7 that meets the preset radial angle can enter the shielding channel 62. This achieves the screening of the proportion of plasma 7 focused in the middle of the discharge chamber 2 entering the shielding channel 62, thereby improving the shielding effect of this application.

[0043] Optionally, the preset radial angle is configured to be greater than 60° and less than 90°. On the one hand, the preset radial angle in this embodiment can reduce the proportion of plasma 7 entering the shielding channel 62; on the other hand, by setting a larger preset radial angle, this embodiment ensures that plasma 7 can only enter the shielding channel 62 through high incidence, that is, the entrance direction of the shielding channel 62 converges towards the tangential direction of the discharge chamber 2, so that plasma 7 cannot reach the inner wall 21 of the discharge chamber 2 along a straight path in the radial direction, but can only exit to the inner wall 21 of the discharge chamber 2 after multiple reflections through the shielding channel 62. Thus, by setting a larger preset radial angle, the straight propagation of plasma 7 in the radial direction is blocked, improving the shielding effect of this embodiment.

[0044] The second channel segment 622 is used to reflect the plasma 7 at least once. Please refer to... Figure 8 This is a schematic diagram of the process of plasma 7 impacting and reflecting in the shielding channel 62 according to an embodiment of this application. The shielding channel 62 provided in this embodiment of the application is used for the gradual reduction of the reflection angle, which can be referred to... Figure 8The diagram illustrates γ1 and γ2. Two perpendicular dashed lines represent the tangent to the curved surface of the sidewall of the shielding unit 61 where the incident plasma 7 impacts, and the perpendicular line to that tangent. If the plasma 7 is a planar reflection, the reflection direction is symmetrical to the incident direction along the perpendicular line, i.e., the direction indicated by the dashed arrow, and the reflection angle is γ2. However, in this embodiment, the shielding channel 62 is configured with a curved sidewall, causing the reflection angle of the plasma 7 after impacting the sidewall to move closer to the perpendicular direction. That is, the actual reflection direction of the plasma 7 is the direction indicated by the solid arrow, and the actual reflection angle is γ1, where γ1 < γ2. This reduces the reflection angle of the plasma 7 after impacting the sidewall, and further, during multiple impacts and reflections of the plasma 7 along the shielding channel 62, the reflection angle gradually decreases. It can be understood that a gradual decrease in the reflection angle of the plasma 7 increases the number of reflections of the plasma 7 in the second channel segment 622, and an increase in the number of reflections reduces the kinetic energy carried by the plasma 7, thereby improving the shielding effect.

[0045] Optionally, the curvature of the sidewall corresponding to the second channel segment 622 is greater than the curvature of the sidewalls corresponding to the first channel segment 621 and the third channel segment 623, causing the shielding channel 62 to bend in the second channel segment 622. Since the reduction in the reflection angle of the plasma 7 is related to the curvature of the surface, when the incident point is a concave surface, the reflection angle of the plasma 7 tends to decrease, and the greater the concavity of the surface, the greater the reduction in the reflection angle of the plasma 7. This embodiment provides a setting where the curvature of the sidewall corresponding to the second channel segment 622 is greater than the curvature of the sidewalls corresponding to the first channel segment 621 and the third channel segment 623, so that the second channel segment 622 is configured with a concave surface whose concavity gradually increases from both sides towards the center. This results in a greater reduction in the reflection angle of the plasma 7 as the incident or exit position deepens, making it difficult for the plasma 7 to pass through the shielding channel 62 through one or two reflections, thereby improving the shielding effect of the shielding channel 62.

[0046] Optionally, the width of the shielding channel 62 narrows from the second channel segment 622 toward the first channel segment 621 and the third channel segment 623, respectively. It is understood that, through the design of the channel width, the inlet and outlet of the shielding channel 62 are configured as narrow openings, thereby reducing the proportion of plasma 7 entering the shielding channel 62 from the center of the discharge chamber 2 by narrowing the plasma 7 incident channel opening.

[0047] The third channel section 623 is used to guide the plasma 7 outwards from the inner wall 21 of the discharge chamber 2. Please refer to... Figure 9This is a schematic diagram of the plasma 7 emission shielding channel 62 provided in this embodiment. After multiple reflections within the shielding channel 62, a portion of the plasma 7 will be emitted from the shielding channel 62. To prevent the plasma 7 from directly impacting the inner wall 21 of the discharge chamber 2, this embodiment guides the plasma 7 exiting the shielding channel 62 through a third channel segment 623, causing the plasma 7 to exit in a direction away from the inner wall 21 of the discharge chamber 2. It can be understood that the exit of the third channel segment 623 can be configured to converge to the tangent of the inner wall 21 of the discharge chamber 2, thereby controlling the emission direction of the plasma 7 and preventing effective sputtering caused by the plasma 7 directly impacting the inner wall 21 in the radial direction. Simultaneously, when the plasma 7 impacts the inner wall 21 of the discharge chamber 2 at a large incident angle, such as 50° or more, the sputtering effect of the plasma 7 will be significantly weakened due to the enhanced reflection effect, thereby reducing the effective sputtering of the inner wall 21 of the discharge chamber 2 and further improving the shielding effect.

[0048] In some optional embodiments, the outer contour 611 of the cross-section of the shielding unit 1 is configured as a Bézier curve, a B-spline curve, or a non-uniform B-spline, including: defining the transition points between the first channel segment 621, the second channel segment 622, and the third channel segment 623 as the first node 611a and the second node 611b; dividing the outer contour 611 into a first parameter curve, a second parameter curve, and a third parameter curve according to the first node 611a and the second node 611b; and confirming the first parameter curve, the second parameter curve, and the third parameter curve according to the processing requirements of the first channel segment 621, the second channel segment 622, and the third channel segment 623 for the plasma 7.

[0049] For example, this application embodiment provides a method for obtaining the outer contour 611 of the cross-section of a shielding channel 62, including: The outer contour 611 of the shielding channel 62 is represented by parameters, and based on the first node 611a between the first channel segment 621 and the second channel segment 622, and the second node 611b between the second channel segment 622 and the third channel segment 623, the outer contour 611 is divided into a first parameter curve, a second parameter curve, and a third parameter curve. The overall parameter t of the outer contour 611 is [0,1], the first node 611a is configured as t1, the second node 611b is configured as t2, the parameter t of the first parameter curve is [0,t1], the parameter t of the second parameter curve is [t1,t2], and the parameter t of the third parameter curve is [t2,1]. Based on the design requirements of the first channel segment 621 for the preset radial angle, the design requirements of the second channel segment 622 for the number of reflections, and the design requirements of the third channel segment 623 for the emission angle, control points of t=[x,y] are obtained. Where x refers to the x-axis coordinate of the cross section corresponding to the outer contour 611, and y refers to the y-axis coordinate of the cross section corresponding to the outer contour 611. The origin of the xy-axis coordinate system can be configured as the center of the discharge chamber 2 or the design center of the cross section of the shielding unit 61. Thus, the coordinate values ​​of each control point of the outer contour 611 can be obtained through the above parameter design. The closed curve formed by the coordinate values ​​of each control point is the outer contour 611 of the cross section of this application.

[0050] For example, taking t1=0.25 and t2=0.75 as examples, please refer to Table 1 for a summary of the coordinate values ​​of each control point: Table 1. List of coordinate values ​​for each control point x y 6 78 -3 78.08 -0.5 80 -4.5 84 -6 84.63 0.5 85.5 8.5 79 6 78 According to Table 1, the outer contour 611 of the corresponding cross section can be obtained through each control point in the embodiments of this application.

[0051] Furthermore, the outer contour 611 also includes: acquiring the first pass rate and second pass rate of plasma 7 escaping the shielding channel 62 through one reflection and two reflections, respectively, corresponding to different combinations of the first parameter curve, the second parameter curve, and the third parameter curve; filtering the first pass rate and / or the second pass rate to obtain combinations of the first parameter curve, the second parameter curve, and the third parameter curve that meet the preset pass rate. For example, setting the preset pass rate as 1% for the first pass rate and 5% for the second pass rate, excluding combinations of the first parameter curve, the second parameter curve, and the third parameter curve with a first pass rate greater than 1% and / or a second pass rate greater than 5%, thereby retaining the outer contour 611 that meets the preset pass rate. Therefore, this application can optimize the outer contour 611 through simulation detection of the first pass rate and the second pass rate, so that the first pass rate and the second pass rate of plasma entering the shielding channel 62 of the Faraday shielding structure 6 provided in this application embodiment are controllable, thereby reducing the proportion of plasma 7 exiting the shielding channel 62 after a limited number of reflections, and improving the shielding effect of this application embodiment.

[0052] In some optional embodiments, the circumferential arrangement angle of the shielding unit 61 is determined based on the erosion peak value of the inner wall 21 of the discharge chamber 2. This includes: obtaining multiple different shielding units 61 corresponding to multiple consecutive circumferential arrangement angles; obtaining a relationship curve between the circumferential arrangement angle and the erosion peak value based on the erosion peak value of multiple different shielding units 61 under the same operating condition; and obtaining the circumferential arrangement angle corresponding to the smallest erosion peak value based on the relationship curve. For example, based on the already obtained outer contour 611 of the cross-section, the circumferential arrangement angle of adjacent shielding units 61 is adjusted, for example: α=2°, α=5°, α=8°, α=10°, α=15°, corresponding to the number of shielding units 61 being 180, 72, 45, 36, and 24, respectively. The shielding effect of the Faraday shielding structure 6 with all circumferential angles is tested, and the erosion peak value of the Faraday shielding structure 6 corresponding to any circumferential angle is obtained. This allows for the plotting of the relationship curve between the circumferential angle and the erosion peak value. Based on the curve, the circumferential angle corresponding to the minimum erosion peak value can be determined. It can be understood that the erosion peak value refers to the erosion value at the point of most severe sputtering erosion on the inner wall 21 of the discharge chamber 2. Simultaneously, the relationship curve can also be used to balance the erosion peak value with the manufacturing cost of the Faraday shielding structure 6. For example, when α=2°, the erosion peak value is the smallest, but the number of shielding units 61 is large, requiring higher processing precision and more advanced materials. In this case, a compromise can be made, or the erosion peak value can meet the usage requirements, but the number of shielding units 61 can be minimized.

[0053] By applying the embodiments of this application, at least the following beneficial effects can be achieved: This embodiment of the application, by including several continuously connected curved surfaces on the sidewall of any shielding unit 61, ensures that any impact of plasma 7 on any point of the shielding unit 61 is a curved surface impact. This greatly improves the sharp-corner impact of plasma 7 on the shielding unit, avoids shielding failure caused by electric field enhancement due to secondary sputtering of plasma 7, and improves the working stability of the Faraday shielding structure 6. Another aspect of this embodiment is the optimization of the structure of the continuously connected curved sidewalls, which gradually reduces the reflection angle of plasma 7 after entering the shielding channel 62. This increases the number of reflections of plasma 7 within the shielding channel 62, improving the physical barrier effect of the shielding channel 62 on plasma 7. Even after multiple reflections, the kinetic energy carried by plasma 7 is significantly reduced due to multiple impacts, making it difficult to effectively sputter onto the inner wall 21 of the discharge chamber 2. This ensures the shielding effect of this embodiment and improves the service life of the discharge chamber 2.

[0054] In the description of this application, the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate directions or positional relationships based on the exemplary directions or positional relationships shown in the accompanying drawings. They are used to facilitate the description or simplification of the embodiments of this application and are not intended to indicate or imply that the device or component referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0055] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0056] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0057] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application, without departing from the technical concept of this application, also fall within the protection scope of the embodiments of this application.

Claims

1. A Faraday shielding structure, disposed near a discharge chamber, for shielding plasma, characterized in that, include: Multiple identical shielding units are arranged in a circumferential pattern along the inner wall of the discharge chamber. Each of the shielding units includes a plurality of continuously connected curved sidewalls, such that a shielding channel is defined between adjacent shielding units based on the sidewalls, for gradually reducing the reflection angle of plasma entering the shielding channel.

2. The Faraday shielding structure according to claim 1, characterized in that, The shielding unit is configured to extend axially along the discharge chamber based on a customized cross-section.

3. The Faraday shielding structure according to claim 2, characterized in that, The shielding channel is divided into a first channel segment, a second channel segment, and a third channel segment based on the direction of plasma propagation. The first channel segment is used to shield plasma with an incident angle smaller than a preset radial angle; The second channel segment is used to reflect the plasma at least once; The third channel segment is used to guide the plasma to exit in a direction away from the inner wall of the discharge chamber.

4. The Faraday shielding structure according to claim 3, characterized in that, The preset radial angle ranges from 60° to 90°.

5. The Faraday shielding structure according to claim 3, characterized in that, The curvature of the sidewall corresponding to the second channel segment is greater than the curvature of the sidewall corresponding to the first channel segment and the third channel segment, causing the shielding channel to bend in the second channel segment.

6. The Faraday shielding structure according to claim 5, characterized in that, The width of the shielding channel narrows from the second channel segment toward the first channel segment and the third channel segment, respectively.

7. The Faraday shielding structure according to claim 5, characterized in that, The outer contour of the cross-section is configured as a Bézier curve, a B-spline curve, or a non-uniform B-spline, including: The transition point between the first channel segment, the second channel segment, and the third channel segment is defined as the first node and the second node; Based on the first node and the second node, the outer contour is divided into a first parameter curve, a second parameter curve, and a third parameter curve; Based on the plasma processing requirements of the first channel segment, the second channel segment, and the third channel segment, the first parameter curve, the second parameter curve, and the third parameter curve are confirmed.

8. The Faraday shielding structure according to claim 7, characterized in that, The outer contour also includes: The first pass rate and the second pass rate of plasma escaping the shielding channel through one reflection and two reflections are obtained respectively for different combinations of the first parameter curve, the second parameter curve and the third parameter curve; The first pass rate and / or second pass rate are filtered to obtain a combination of the first parameter curve, the second parameter curve and the third parameter curve that meet the preset pass rate.

9. The Faraday shielding structure according to claim 3, characterized in that, Based on the erosion peak value of the inner wall of the discharge chamber, the circumferential arrangement angle of the shielding unit is determined, including: Based on the circumferential arrangement angles of multiple consecutive values, obtain the corresponding multiple different shielding units; Based on the erosion peak values ​​of multiple different shielding units under the same operating conditions, obtain the relationship curve between the circumferential layout angle and the erosion peak value; Based on the relationship curve, obtain the circumferential layout angle corresponding to the minimum erosion peak value.

10. An ion source, comprising: The discharge chamber, the coil assembly disposed around the outer wall of the discharge chamber, and the Faraday shielding assembly disposed near the inner wall of the discharge chamber, characterized in that the Faraday shielding assembly adopts the Faraday shielding structure according to any one of claims 1-9.

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