Faraday structure and beam uniformity monitoring method

Abstract

The invention relates to the technical field of semiconductor manufacturing, and provides a Faraday structure and a beam uniformity monitoring method. The Faraday structure comprises a Faraday cylinder for scanning the ion concentration of the ion beam through motion sampling; the Faraday cup comprises at least two graphite layers, all the graphite layers extend in the first direction and are distributed at intervals in the second direction, each graphite layer is used for sampling the ion concentration of the scanning ion beam in the corresponding area, the first direction is the sampling movement direction of the Faraday cup, and the second direction is the sampling movement direction of the Faraday cup. The second direction is perpendicular to the first direction; and the insulating layer is arranged between the two adjacent graphite layers, so that the two adjacent graphite layers are insulated and isolated from each other. By adopting the Faraday structure provided by the invention, the beam uniformity in the horizontal direction and the vertical direction is accurately monitored, the abnormal ion implantation dose distribution of the wafer is avoided, the machine process capability of the ion implanter is improved, and the product yield is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a Faraday structure and a beam current uniformity monitoring method. Background Art

[0002] Ion implanters have two beam current modes, namely spot beam and scanned ion beam. The spot beam is a beam of ions compressed by a magnetic field into a cylindrical beam. The scanned ion beam is a parallel beam of individual ions formed by sweeping the cylindrical beam 11 of the spot beam through special electric field control, as Figure 1 shown. Monitoring the beam current uniformity of the scanned ion beam is very important, and the ion implanter itself has means for detecting the beam profile.

[0003] As Figure 2 shown, the cylindrical beam of the spot beam (Spot Beam) 21 is swept into a parallel beam of individual ions of the scanned ion beam 23 through special electric field control; the existing Faraday Cup 22 of the machine tool collects the ion concentration through the telescopic movement in the beam scanning direction of the spot beam 21 (the arrow in the figure is the sampling movement direction of the Faraday Cup 22), and then calculates the distribution of the beam profile of the implanted ions of the ion implanter through a specific algorithm to judge the beam current uniformity of the scanned ion beam 23. In an ideal state, the cross-section of the cylindrical beam with uniform ion concentration distribution (i.e., the spot beam 21) after being swept (i.e., the scanned ion beam 23) is also uniformly distributed. However, there may be problems with the compression of the spot beam by the magnetic field, resulting in uneven distribution in the horizontal or vertical direction of the spot beam. The existing Faraday Cup of the machine tool can accurately monitor the beam current uniformity in the horizontal direction, but cannot monitor the abnormal distribution in the vertical direction. The abnormal distribution of the beam current uniformity in the vertical direction that is not monitored will cause abnormal distribution of the ion implantation dose in the vertical direction of the wafer (Wafer). Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a Faraday structure and a beam current uniformity monitoring method, which can accurately monitor the beam current uniformity in the horizontal and vertical directions of the scanned ion beam of the ion implanter, so as to improve the process capability of the machine tool and the product yield.

[0005] To solve the above problems, the present invention provides a Faraday structure, including a Faraday cup for sampling the ion concentration of a scanning ion beam through motion sampling; the Faraday cup includes: at least two graphite layers, all the graphite layers extend along a first direction and are spaced apart along a second direction, and each graphite layer is used for sampling the ion concentration of the scanning ion beam in a corresponding area, wherein the first direction is the sampling motion direction of the Faraday cup, and the second direction is perpendicular to the first direction; an insulating layer is disposed between adjacent two graphite layers to insulate and isolate adjacent two graphite layers from each other.

[0006] To solve the above problems, the present invention also provides a beam current uniformity monitoring method, including the following steps: providing the Faraday structure of the present invention, and electrically connecting each graphite layer to an ammeter, the ammeter is used for detecting the current corresponding to the ion concentration sampled by the graphite layer; detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at each sampling point of a single graphite layer to monitor whether the ion concentration distribution of the scanning ion beam in the corresponding area of the graphite layer along the first direction is abnormal; and detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at the corresponding sampling points of multiple graphite layers to monitor whether the ion concentration of the scanning ion beam along the second direction is abnormal.

[0007] Through the above technical solutions, by optimizing and transforming the Faraday cup, at least two graphite layers insulated and spaced by an insulating layer are provided in the vertical direction to sample the ion concentrations of the scanning ion beam in different areas respectively, and by comparing the ion concentrations sampled by each graphite layer, it is possible to monitor whether the ion concentration of the scanning ion beam along the vertical direction is abnormal, and the accuracy in the horizontal direction is ensured. The beam current uniformity in both the horizontal direction and the vertical direction is accurately monitored, avoiding abnormal ion implantation dose distribution on the wafer, improving the machine process ability of the ion implanter, and enhancing the product yield. Description of the Drawings

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0009] Figure 1 Schematic diagram of the state of the scanning ion beam;

[0010] Figure 2 Schematic diagram of monitoring beam current uniformity using the Faraday structure in the prior art;

[0011] Figure 3 Schematic diagram of the Faraday structure provided by an embodiment of the present invention;

[0012] Figure 4 For adopting Figure 3 The schematic diagram for monitoring the beam uniformity by using the Faraday structure shown;

[0013] Figure 5 The flowchart of the beam uniformity monitoring method provided by an embodiment of the present invention.

[0014] Explanation of reference numerals:

[0015] 11 Cylindrical beam 12 Parallel beam

[0016] 21 Point beam 22 Faraday cup 23 Scanning ion beam

[0017] 30 Faraday structure

[0018] 31 First graphite layer 32 Second graphite layer 33 Insulating layer

[0019] 311 First protrusion 321 Second protrusion

[0020] 35 First ammeter 36 Second ammeter Specific implementation manner

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative efforts shall fall within the protection scope of the present invention.

[0022] An embodiment of the present invention provides a Faraday structure, including a Faraday cup for sampling the ion concentration of a scanning ion beam through motion sampling; the Faraday cup includes: at least two graphite layers, all the graphite layers extend along a first direction and are spaced apart along a second direction, and each graphite layer is used for sampling the ion concentration of the scanning ion beam in a corresponding area, wherein the first direction is the sampling motion direction of the Faraday cup, and the second direction is perpendicular to the first direction; an insulating layer is disposed between two adjacent graphite layers to insulate and isolate the two adjacent graphite layers from each other. By optimizing and transforming the Faraday cup, at least two graphite layers insulated and spaced apart by the insulating layer are provided in the vertical direction to sample the ion concentration of the scanning ion beam in different areas respectively, and by comparing the ion concentrations sampled by each graphite layer, it is possible to monitor whether the ion concentration of the scanning ion beam in the vertical direction is abnormal, and the accuracy in the horizontal direction is ensured. The beam uniformity in both the horizontal direction and the vertical direction is accurately monitored, avoiding the abnormal distribution of the ion implantation dose on the wafer, improving the machine process ability of the ion implanter, and enhancing the product yield.

[0023] Please refer to Figures 3 to 4 together, where Figure 3 is a schematic diagram of a Faraday structure provided by an embodiment of the present invention; Figure 4 is a schematic diagram of using the Figure 3 shown Faraday structure to monitor the beam uniformity.

[0024] As Figures 3 to 4 shown, the Faraday structure 30 described in this embodiment includes a Faraday cup for sampling the ion concentration of the ion beam by moving and sampling. The Faraday cup includes: a first graphite layer 31, a second graphite layer 32, and an insulating layer 33.

[0025] Specifically, both the first graphite layer 31 and the second graphite layer 32 extend along the first direction D1, and the first graphite layer 31 and the second graphite layer 32 are spaced apart along the second direction D2. The first graphite layer 31 and the second graphite layer 32 are used to sample the ion concentration of the scanned ion beam in the corresponding regions respectively. Wherein, the first direction D1 is the sampling movement direction of the Faraday cup, and the second direction D2 is perpendicular to the first direction D1. The insulating layer 33 is disposed between the first graphite layer 31 and the second graphite layer 32 to insulate and isolate the first graphite layer 31 and the second graphite layer 32 from each other.

[0026] In this embodiment, by optimizing and transforming the Faraday cup, the first graphite layer 31 and the second graphite layer 32 insulated and spaced apart by the insulating layer 33 are provided in the second direction D2 (i.e., the vertical direction) to sample the ion concentration of the scanned ion beam in different regions respectively, and compare the ion concentrations sampled by the first graphite layer 31 and the second graphite layer 32, so as to monitor whether the ion concentration of the scanned ion beam along the second direction D2 is abnormal, and ensure the accuracy in the first direction D1 (i.e., the horizontal direction). The beam uniformity in both the horizontal direction and the vertical direction is accurately monitored, avoiding abnormal ion implantation dose distribution on the wafer, improving the machine process ability of the ion implanter, and improving the product yield.

[0027] In this embodiment, the structures of the first graphite layer 31 and the second graphite layer 32 are the same, which is convenient for the production of the Faraday cup, and eliminates the interference items of ion concentration sampling and improves the sampling accuracy.

[0028] In this embodiment, the cross-sectional shape of the Faraday cup is rectangular; it should be noted that the cross-sectional shape of the Faraday cup is not limited and can use a suitable shape according to the needs of the machine.

[0029] In this embodiment, the material of the insulating layer 33 includes graphite microcrystalline ceramics. The insulation and high-temperature resistance of the graphite microcrystalline ceramics meet the requirements.

[0030] In some embodiments, the Faraday cylinder may also include multiple graphite layers spaced along the second direction D2. All the graphite layers have the same structure (as shown by the first graphite layer 31 / second graphite layer 32 in Figure 3 . Accordingly, an insulating layer 33 is provided between any two adjacent graphite layers. That is, the Faraday cylinder is modified. By adding an insulating layer, the original entire graphite layer of the Faraday cylinder is divided into multiple parts in the vertical direction, and multiple sampling values are obtained when sampling and scanning the ion concentration of the moving ion beam, so that the beam current uniformity in the horizontal and vertical directions can be accurately monitored. By refining the distribution of the division of the Faraday cylinder, increasing the number of insulating layers, and increasing the number of divided graphite layer stratifications, more accurate beam profile sampling data can be obtained.

[0031] Please refer to Figures 3 to 4 again. In this embodiment, the first graphite layer 31 has a first protrusion 311 facing the second graphite layer 32, and the insulating layer 33 has a first recess corresponding to the first protrusion 311 (the first protrusion 311 coincides with the first recess in the figure). The second graphite layer 32 has a second protrusion 321 facing the first graphite layer 31, and the insulating layer 33 has a second recess corresponding to the second protrusion 321 (the second protrusion 321 coincides with the second recess in the figure). By providing corresponding protrusions and recesses, it is convenient to set the insulating layer and can improve the sampling accuracy.

[0032] In this embodiment, the first protrusion 311 and the second protrusion 321 are diagonally arranged.

[0033] In other embodiments, only the first graphite layer 31 may have a first protrusion 311 facing the second graphite layer 32, and the insulating layer 33 has a first recess corresponding to the first protrusion 311. Alternatively, only the second graphite layer 32 may have a second protrusion 321 facing the first graphite layer 31, and the insulating layer 33 has a second recess corresponding to the second protrusion 321. The number of the first protrusion 311 and the second protrusion 321 may each be one or more. Whether to provide protrusions and the number of protrusions can be reasonably selected according to manufacturing and accuracy requirements.

[0034] Please refer to Figures 3 to 4, in this embodiment, the Faraday structure further includes: a first ammeter 35 and a second ammeter 36. The first ammeter 35 is electrically connected to the first graphite layer 31 for detecting the current corresponding to the ion concentration sampled by the first graphite layer 31; the second ammeter 36 is electrically connected to the second graphite layer 32 for detecting the current corresponding to the ion concentration sampled by the second graphite layer 32.

[0035] By detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at each sampling point of the first graphite layer 31, it is possible to monitor whether the ion concentration distribution of the scanning ion beam along the first direction D1 in the corresponding area of the first graphite layer 31 is abnormal; by detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at each sampling point of the second graphite layer 32, it is possible to monitor whether the ion concentration distribution of the scanning ion beam along the first direction D1 in the corresponding area of the second graphite layer 32 is abnormal. The monitoring of the beam uniformity in the horizontal direction can refer to the existing monitoring methods for the beam uniformity in the horizontal direction. Further, a graph can be drawn based on the magnitudes of the currents at each sampling point to visually observe the beam uniformity.

[0036] By detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at the corresponding sampling points of the first graphite layer 31 and the second graphite layer 32, it is possible to monitor whether the ion concentration of the scanning ion beam along the second direction D2 is abnormal. The corresponding sampling points are the sampling points with the same coordinates in the first direction D1 on the first graphite layer 31 and the second graphite layer 32, that is, at the same sampling time, the coordinates of the sampling points on the first graphite layer 31 in the first direction are the same as the coordinates of the sampling points on the second graphite layer 32 in the first direction. By comparing the magnitudes of the currents corresponding to the ion concentrations of the sampling points with the same horizontal coordinates, it is possible to monitor whether the ion concentration in the vertical direction is abnormal. The closer the two compared values are, the better the beam uniformity. Further, a graph can be drawn based on the current ratios of each corresponding sampling point to visually observe the beam uniformity.

[0037] When the Faraday cylinder includes multiple graphite layers spaced apart along the second direction D2, each graphite layer is electrically connected to an ammeter correspondingly, and each ammeter is used to detect the current corresponding to the ion concentration sampled by the corresponding graphite layer. By detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at each sampling point of a single graphite layer, it is possible to monitor whether the ion concentration distribution of the scanning ion beam along the first direction is abnormal; by detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at the corresponding sampling points of multiple graphite layers, it is possible to monitor whether the ion concentration of the scanning ion beam along the second direction is abnormal.

[0038] The working principle of the Faraday structure provided in this embodiment is further explained below. In this embodiment, the original Faraday cylinder is modified by adding an insulating layer in the middle of the original Faraday cylinder, dividing the entire Faraday cylinder into two parts with the same area in the upper and lower directions. Through special electric field control, the cylindrical beam current of the spot beam 41 is swept into a parallel beam current of single ions, i.e., the scanning ion beam 43. When sampling the ion concentration during movement, two values are obtained for the upper and lower parts. After monitoring the ratio of the values of the upper and lower parts and analyzing the graph, more accurate beam current uniformity is obtained, thereby monitoring the abnormal distribution of ion concentration in the vertical direction and ensuring the accuracy in the horizontal direction.

[0039] Specifically, define the value obtained when sampling the ion concentration during movement for the upper part (the first graphite layer 31) as I1, and the value obtained when sampling the ion concentration during movement for the lower part (the second graphite layer 32) as I2.

[0040] As Figure 4 shown in the second row of [reference], in the ideal state, the cross-section of the cylindrical beam current (i.e., the spot beam 41) with uniform ion concentration distribution after being swept (i.e., the scanning ion beam 43) is also uniformly distributed. Due to the uniform ion concentration distribution, when sampling the ion concentration during movement for the upper part (the first graphite layer 31), the values I1 obtained at each sampling point are the same. In this embodiment, they are all 2, indicating that the corresponding area of the first graphite layer 31 in the horizontal direction satisfies the beam current uniformity; when sampling the ion concentration during movement for the lower part (the second graphite layer 32), the values I2 obtained at each sampling point are the same. In this embodiment, they are all 2, indicating that the corresponding area of the second graphite layer 32 in the horizontal direction satisfies the beam current uniformity. When drawing the graph, since the graphs corresponding to the values I1 and I2 overlap, Figure 4 only the graph corresponding to the value I2 is shown in the second row of [reference]. Correspondingly, due to the uniform ion concentration distribution, the ratio of the values I1 and I2 is 1 (the closer the I1 / I2 ratio is to 1, the better the uniformity in the vertical direction), indicating that the beam current uniformity is satisfied in the vertical direction. Therefore, the monitoring result is normal (Pass).

[0041] As Figure 4As shown in the third line of [reference], when there is a problem with the compression of the magnetic field on the point beam, it causes the distribution of the ion concentration of the point beam to be uneven in the horizontal direction. Due to the uneven distribution of the ion concentration in the horizontal direction, when the upper part (the first graphite layer 31) moves to sample the ion concentration, the values I1 obtained at each sampling point are different (as shown in the figure, the values change from 1 to 3), indicating that the corresponding area of the first graphite layer 31 in the horizontal direction does not meet the beam current uniformity; when the lower part (the second graphite layer 32) moves to sample the ion concentration, the values I2 obtained at each sampling point are different (as shown in the figure, the values change from 1 to 3), indicating that the corresponding area of the second graphite layer 32 in the horizontal direction does not meet the beam current uniformity. When drawing, since the graphs corresponding to the values I1 and I2 coincide, Figure 4 only the graph corresponding to the value I2 is shown in the third line of [reference]. Correspondingly, since the ion concentration is evenly distributed in the vertical direction, the ratio of the value I1 to the value I2 is 1, indicating that the beam current uniformity is met in the vertical direction. Therefore, the monitoring result is abnormal (Fail).

[0042] As Figure 4 shown in the fourth line of [reference], when there is a problem with the compression of the magnetic field on the point beam, it causes the distribution of the ion concentration of the point beam to be uneven in the vertical direction. Since the ion concentration is evenly distributed in the horizontal direction, when the upper part (the first graphite layer 31) moves to sample the ion concentration, the values I1 obtained at each sampling point are the same (all 1 in this embodiment), indicating that the corresponding area of the first graphite layer 31 in the horizontal direction meets the beam current uniformity; when the lower part (the second graphite layer 32) moves to sample the ion concentration, the values I2 obtained at each sampling point are the same (all 2 in this embodiment), indicating that the corresponding area of the second graphite layer 32 in the horizontal direction meets the beam current uniformity. Since the ion concentration is unevenly distributed in the vertical direction, the ratio of the value I1 to the value I2 is 0.5, indicating that the beam current uniformity is not met in the vertical direction. Therefore, the monitoring result is abnormal (Fail).

[0043] It can be seen from the above that the Faraday structure provided in this embodiment can monitor whether the ion concentration of the scanned ion beam in the vertical direction is abnormal and ensure the accuracy in the horizontal direction; the beam current uniformity in both the horizontal direction and the vertical direction is accurately monitored, avoiding abnormal distribution of the ion implantation dose on the wafer, improving the machine process ability of the ion implanter, and improving the product yield.

[0044] Based on the same inventive concept, the present invention also provides a method for monitoring beam current uniformity, which can monitor whether the ion concentration of the scanned ion beam in the vertical direction is abnormal and ensure the accuracy in the horizontal direction by implementing beam current uniformity monitoring using the Faraday structure described in the present invention.

[0045] Please refer to Figure 5, which is a flowchart of the beam uniformity monitoring method provided by an embodiment of the present invention. As Figure 5 shown, the beam uniformity monitoring method provided in this embodiment includes the following steps: S1, providing the Faraday structure of the present invention, and electrically connecting each layer of the graphite layer to an ammeter, where the ammeter is used to detect the current corresponding to the ion concentration sampled by the graphite layer; S2, detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at each sampling point of a single layer of the graphite layer to monitor whether the ion concentration distribution of the scanned ion beam in the corresponding area of the graphite layer along the first direction is abnormal; and S3, detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at the corresponding sampling points of multiple layers of the graphite layer to monitor whether the ion concentration of the scanned ion beam along the second direction is abnormal. It should be noted that the examples and application scenarios implemented by the above steps are the same as those Figures 3 - 4 implemented, but are not limited to the content disclosed in the above embodiments.

[0046] In this embodiment, the step of detecting and comparing the magnitudes of the currents corresponding to the ion concentrations sampled at the corresponding sampling points of multiple layers of the graphite layer to monitor whether the ion concentration of the scanned ion beam along the second direction is abnormal specifically includes: (31) respectively obtaining a first current value of a graphite layer in two adjacent graphite layers and a second current value of the other graphite layer; (32) respectively obtaining a first current value of a graphite layer in two adjacent graphite layers and a second current value of the other graphite layer; (33) synchronously (SYNC) converting the first current value and the second current value into corresponding first digital signals and second digital signals through analog-to-digital conversion; and (34) monitoring the ratio of the first digital signal to the second digital signal, and determining that the ion concentration of the scanned ion beam along the second direction is normal when the ratio is within a preset threshold range. Specifically, the preset threshold range is 0.9 to 1.1. The closer the ratio is to 1, the better the uniformity in the vertical direction.

[0047] In this embodiment, the corresponding sampling points are the sampling points with the same coordinates in the first direction D1 on the first graphite layer 31 and the second graphite layer 32. That is, at the same sampling time, the coordinates of the sampling points on the first graphite layer 31 in the first direction are the same as the coordinates of the sampling points on the second graphite layer 32 in the first direction. At the same sampling time, the first current value and the second current value have the same coordinates in the first direction.

[0048] In some embodiments, any one of the average value, median value, maximum value, and minimum value of all sampling values of the same sampling point can be obtained as the corresponding current value.

[0049] It should be noted that in the above embodiments, each embodiment focuses on the differences from other embodiments. For the same / similar parts among the embodiments, reference can be made to each other.

[0050] The terms "including" and "having" and their variants involved in the documents of the present invention are intended to cover non-exclusive inclusion. The terms "first", "second", etc. are used to distinguish similar objects and do not necessarily need to be used to describe a specific order or sequence. Unless the context clearly indicates, it should be understood that the data used in this way can be interchanged under appropriate circumstances. The term "one or more" depends at least in part on the context and can be used to describe a feature, structure or property in a singular sense, or can be used to describe a combination of features, structures or features in a plural sense. The term "based on" can be understood as not necessarily aiming to express a set of exclusive factors, but alternatively, also at least in part depending on the context, allowing for the existence of other factors that are not necessarily explicitly described. Additionally, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. Furthermore, in the above description, the description of well-known components and technologies is omitted to avoid unnecessarily confusing the concepts of the present invention.

[0051] The above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A Faraday structure comprising a Faraday cage for scanning the ion concentration of an ion beam by motion sampling; It is characterized in that The Faraday cage comprises: At least two graphite layers, all of which extend along a first direction and are spaced apart along a second direction, and each of the graphite layers is used to sample the ion concentration of the scanning ion beam in a corresponding area, wherein the first direction is the sampling movement direction of the Faraday cage, and the second direction is perpendicular to the first direction; The insulating layer is arranged between two adjacent graphite layers so as to insulate and isolate the two adjacent graphite layers from each other.

2. The Faraday structure according to claim 1, characterized in that: The material of the insulating layer includes graphite microcrystalline ceramics.

3. The Faraday structure according to claim 1, characterized in that: The Faraday cage includes multiple graphite layers spaced apart along the second direction, and all the graphite layers have the same structure; the insulating layer is disposed between any two adjacent graphite layers.

4. The Faraday structure according to claim 1, characterized in that: One of the two adjacent graphite layers has at least one first protrusion facing the other graphite layer, and the insulating layer between the two adjacent graphite layers has a first recessed portion corresponding to the first protrusion; and / or The other graphite layer of the two adjacent graphite layers has at least one second protrusion facing the one graphite layer, and the insulating layer between the two adjacent graphite layers has a second recessed portion corresponding to the second protrusion.

5. The Faraday structure according to claim 4, characterized in that: When one of the two adjacent graphite layers has at least one first protrusion facing the other graphite layer, and the other of the two adjacent graphite layers has at least one second protrusion facing the one graphite layer, the first protrusion and the second protrusion are arranged diagonally.

6. The Faraday structure according to claim 1, characterized in that: The Faraday structure further includes: a plurality of ammeters electrically connected to the graphite layer in a one-to-one correspondence, for detecting the current corresponding to the ion concentration sampled by the graphite layer; By detecting and comparing the current corresponding to the ion concentration sampled at each sampling point of the single-layer graphite layer, it is possible to monitor whether the ion concentration distribution of the scanning ion beam along the first direction in the corresponding area of ​​the graphite layer is abnormal; By detecting and comparing the current magnitudes corresponding to the ion concentrations sampled at the corresponding sampling points of the multiple graphite layers, it is possible to monitor whether the ion concentration of the scanning ion beam along the second direction is abnormal.

7. A beam uniformity monitoring method, characterized in that: The steps include: Providing a Faraday structure as claimed in any one of claims 1 to 5, and electrically connecting each of the graphite layers to an ammeter, wherein the ammeter is used to detect the current corresponding to the ion concentration sampled by the graphite layer; Detecting and comparing the current corresponding to the ion concentration sampled at each sampling point of the single-layer graphite layer to monitor whether the ion concentration distribution of the scanning ion beam along the first direction in the corresponding area of ​​the graphite layer is abnormal; as well as The current magnitudes corresponding to the ion concentrations sampled at the corresponding sampling points of the multiple graphite layers are detected and compared to monitor whether the ion concentration of the scanning ion beam along the second direction is abnormal.

8. The method according to claim 7, characterized in that The step of detecting and comparing the current magnitudes corresponding to the ion concentrations sampled at the corresponding sampling points of the multiple graphite layers to monitor whether the ion concentration of the scanning ion beam along the second direction is abnormal specifically includes: Respectively obtaining a first current value of one graphite layer and a second current value of the other graphite layer in two adjacent graphite layers; Synchronously converting the first current value and the second current value into corresponding first digital signals and second digital signals through analog-to-digital conversion; The ratio of the first digital signal to the second digital signal is monitored, and when the ratio is within a preset threshold range, it is determined that the ion concentration of the scanning ion beam along the second direction is normal.

9. The method according to claim 8, characterized in that The average value, median value, maximum value, and minimum value of all sampled values ​​at the same sampling point are obtained as the corresponding current value.

10. The method according to claim 8, characterized in that At the same sampling time, the first current value and the second current value have the same coordinate in the first direction.

11. The method according to claim 8, characterized in that The preset threshold range is 0.9 to 1.1.

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