Process chamber and control method
By introducing a magnetic field control component into the process chamber to detect and adjust the magnetic field strength, the problem of etching non-uniformity caused by plasma density bias in certain areas was solved, thereby improving the uniformity of plasma at the wafer edge and the etching yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-22
- Publication Date
- 2026-03-31
AI Technical Summary
During the etching process of semiconductor devices, the plasma density tends to be biased towards a certain area, leading to problems such as uneven etching and reduced etching yield.
A magnetic field control component, including a main region coil assembly and an edge coil assembly, is used to detect the magnetic field strength through a magnetic field detection element and adjust the current or voltage of the coil to achieve magnetic field compensation and improve the uniformity of the plasma.
This improved the uniformity of plasma at the wafer edge, enhanced etching uniformity and yield, and reduced labor costs.
Smart Images
Figure CN121768942A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, specifically to a process chamber and its control method. Background Technology
[0002] Currently, in the etching process of semiconductor devices, the wafer is usually placed on the upper surface of the lower electrode. An upper radio frequency power supply is applied to the upper electrode on top of the lower electrode, and a lower radio frequency power supply is applied to the lower electrode. Electrons are accelerated by the electric field and collide with gas molecules in the process chamber to generate plasma. During the process, the wafer undergoes physical and chemical reactions on the surface of the plasma to etch the desired shape.
[0003] During plasma etching, electrons randomly collide with gas molecules in the process chamber, causing uneven plasma distribution. On the one hand, this causes the incident angle of local ion bombardment of the wafer to deviate from the vertical direction, resulting in poor control of the size value of the pattern on the wafer and reducing the etching yield. On the other hand, it causes the plasma density to be biased to a certain area, thereby reducing the uniformity of etching. Summary of the Invention
[0004] To address the aforementioned technical problems, this application provides a process chamber and a control method that can improve the problem that the plasma density in existing process chambers tends to be biased towards a certain area, thus reducing the uniformity of etching.
[0005] To address the aforementioned technical problems, in a first aspect, embodiments of this application provide a process chamber and a control method, the process chamber comprising: Upper electrode assembly; The lower electrode assembly is disposed below the upper electrode assembly; Multiple magnetic field detection elements are spaced apart along the edge of the lower electrode assembly, and the magnetic field detection elements are used to detect the magnetic field strength. A magnetic field control unit is disposed above the upper electrode assembly. The magnetic field control unit includes a main region coil assembly and an edge coil assembly. The main region coil assembly includes one or more main coils, and the multiple main coils are sequentially nested along the radial direction of one of the main coils. The edge coil assembly includes multiple edge coils, each corresponding to one of the multiple magnetic field detection elements. The multiple edge coils are arranged at intervals around the main coil assembly in the circumferential direction of the main coil.
[0006] Optionally, the process chamber further includes: A controller is used to adjust the current or voltage of the main coil and the edge coil according to the magnetic field strength.
[0007] Optionally, the lower electrode assembly includes: Load-bearing structure; A focusing ring is disposed around the outer side of the load-bearing structure; The plurality of magnetic field detection elements are built into the focusing ring. The bottom of the focusing ring is provided with a first through hole corresponding to each of the plurality of magnetic field detection elements. The supporting structure is provided with a channel corresponding to each of the first through holes. The controller is connected to the magnetic field detection elements through the channel and the first through hole.
[0008] Optionally, the load-bearing structure includes: An electrostatic chuck has a boss on the top, and a focusing ring is arranged around the outside of the boss. The electrostatic chuck has a plurality of second through holes that are connected to the first through hole one by one. The first interface disk is disposed on the lower surface of the electrostatic chuck, and the first interface disk is provided with a plurality of third through holes that communicate with the second through holes one by one; A support ring is disposed on the lower surface of the first interface disk, and the support ring is provided with a plurality of fourth through holes corresponding to and communicating with the third through hole; The second interface plate is disposed on the lower surface of the support ring; The second through hole, the third through hole, and the fourth through hole constitute the channel.
[0009] Secondly, embodiments of this application also provide a control method for the process chamber described in the above embodiments, comprising: Main area coil assembly adjustment: Based on the first magnetic field strength measured by the plurality of magnetic field detection elements, adjust the current or voltage of the main area coil assembly so that the average value of the plurality of first magnetic field strengths falls within a first preset range; Edge coil assembly adjustment: Based on the first magnetic field strength measured by the plurality of magnetic field detection elements, adjust the current or voltage of the edge coil assembly so that the plurality of first magnetic field strengths all fall within the first preset range.
[0010] Optionally, the main coil assembly includes a first main coil and a second main coil arranged around the first main coil; The steps for adjusting the main region coil assembly include: Turn on the first main coil and the second main coil to obtain the multiple first magnetic field strengths measured by the multiple magnetic field detection elements; If the average value of the plurality of first magnetic field strengths exceeds the first preset range, the current or voltage of the first main coil and / or the second main coil is adjusted so that the average value of the plurality of first magnetic field strengths falls within the first preset range.
[0011] Optionally, the control method further includes: If the average value of the plurality of first magnetic field strengths is less than the lower limit of the first preset range, then increase the current or voltage of the first main coil and / or the second main coil. If the average value of the plurality of first magnetic field strengths is greater than the upper limit of the first preset range, then the current or voltage of the first main coil and / or the second main coil is reduced.
[0012] Optionally, if the average value of the plurality of first magnetic field strengths is less than the lower limit of the first preset range, the current or voltage of the first main coil and / or the second main coil is increased, specifically including: If the average value of the first magnetic field strength is less than the lower limit of the first preset range, then obtain the multiple second magnetic field strengths measured by the multiple magnetic field detection elements when only the first main coil is turned on. If the average value of the plurality of second magnetic field strengths is greater than the upper limit of the second preset range, then the current or voltage of the second main coil is increased.
[0013] Optionally, the control method further includes: If the average value of the plurality of second magnetic field strengths is less than or equal to the upper limit of the second preset range, then obtain the plurality of third magnetic field strengths measured when only the second main coil is turned on, and compare the relationship between the average value of the plurality of third magnetic field strengths and the third preset range. If the average value of the plurality of third magnetic field strengths is greater than the upper limit of the third preset range, the current or voltage of the first main coil is increased; if the average value of the plurality of third magnetic field strengths is less than or equal to the upper limit of the third preset range, the current or voltage of the first main coil and the second main coil are increased simultaneously.
[0014] Optionally, if the average value of the plurality of first magnetic field strengths is greater than the upper limit of the first preset range, then the current or voltage of the first main coil and / or the second main coil is reduced, specifically including: If the average value of the first magnetic field strength is greater than the upper limit of the first preset range, then obtain the multiple second magnetic field strengths measured by the multiple magnetic field detection elements when only the first main coil is turned on. If the average value of the plurality of second magnetic field strengths is less than or equal to the upper limit of the second preset range, then the current or voltage of the second main coil is reduced.
[0015] Optionally, the control method further includes: If the average value of the plurality of second magnetic field strengths is greater than the upper limit of the second preset range, then the relationship between the average value of the plurality of third magnetic field strengths and the third preset range is compared. If the average value of the plurality of third magnetic field strengths is less than or equal to the upper limit of the third preset range, then the current or voltage of the first main coil is reduced; if the average value of the plurality of third magnetic field strengths is greater than the upper limit of the third preset range, then the current or voltage of both the first main coil and the second main coil are reduced simultaneously.
[0016] Optionally, the step of adjusting the edge coil assembly includes: If the average of the plurality of first magnetic field strengths falls within the first preset range, then at least one round of calibration is performed until the requirement is met; wherein each round of calibration includes: Obtain the current magnetic field strength detected by each magnetic field detection element; If all the current magnetic field strengths are within the first preset range, then the requirement is met. If any of the current magnetic field strengths is outside the first preset range, the current or voltage of the edge coil corresponding to the magnetic field detection element is adjusted so that the current magnetic field strength detected by the magnetic field detection element falls within the first preset range.
[0017] Optionally, for the adjustment of current or voltage of the same magnetic field sensing element, the adjustment range in the next calibration is smaller than the adjustment range in the previous calibration.
[0018] Optionally, in the first round of calibration, the change in the first magnetic field strength Bi, ΔBi, caused by adjusting the current or voltage of any magnetic field detection element, satisfies the following relationship: ΔBi = {|Bi - B1min|, |Bi - B1max|}min, where B1min and B1max are the lower and upper limits of the first preset range, respectively; and / or, The change in the first magnetic field strength in the next calibration is half the change in the first magnetic field strength in the previous calibration.
[0019] Optionally, if any of the current magnetic field strengths is outside the first preset range, the current or voltage of the edge coil corresponding to the magnetic field detection element is adjusted so that the current magnetic field strength detected by the magnetic field detection element falls within the first preset range, specifically including: The magnetic field adjustment amplitude of each edge coil is determined based on the differences between the current magnetic field strength and the first preset range. For any of the aforementioned edge coils, based on the applied current or voltage and the magnetic field adjustment amplitude corresponding to the edge coil, a relationship is established between the magnetic field adjustment amplitude and the applied current or voltage of the edge coil. Based on all the relationships, determine the current or voltage supplied to each of the said edge coils; Apply a corresponding current or voltage to each of the edge coils.
[0020] Optionally, all the relations are: ΔB1= n1*f(C1)+ n2*f(C2)+ n3*f(C3)+……n i *f(C i ) ΔB2= n i *f(C1)+ n1*f(C2)+ n2*f(C3)+……n （i-1） *f(Ci); ΔB3= n （i-1） *f(C1)+ n i *f(C2)+ n1*f(C3)+……n （i-2） *f(Ci); ……, ΔBi= n2*f(C1)+ n3*f(C2)+……n i *f(C3)+n1*f(Ci); Wherein, ΔBi is the magnetic field adjustment amplitude of the edge coil Ci; n1 is the influence factor of the edge coil C1 on the detection result of the magnetic field detection element S1 corresponding to the edge coil C1; n2 is the influence factor of the edge coil C2, which is the first nearest neighbor on one side of the edge coil C1, on the detection result of the magnetic field detection element S1; n3 is the influence factor of the edge coil C3, which is the second nearest neighbor on one side of the edge coil C1, on the detection result of the magnetic field detection element S1; ..., n i f(C) is the influence factor of the (i-1)th nearest neighbor edge coil Ci on the detection result of the magnetic field detection element S1. i ) represents the current magnetic field strength of the edge coil Ci.
[0021] As described above, the process chamber of this application includes a magnetic field control unit comprising a main region coil assembly and an edge coil assembly. The main region coil assembly provides a magnetic field above the lower electrode assembly. Multiple magnetic field detection elements are spaced along the edge of the lower electrode assembly, each capable of detecting the magnetic field strength at a corresponding location. The edge coil assembly includes multiple edge coils spaced around the main region coil assembly in the circumferential direction. When the magnetic field strength detected by a certain magnetic field detection element is too high or too low, magnetic field compensation can be achieved by adjusting the current or voltage of the edge coil corresponding to that detection element. In other words, by adjusting the current or voltage of the edge coils, the unevenness of the magnetic field generated by the main coil at certain locations can be finely adjusted locally, thereby improving the uniformity of the plasma at the wafer edge and thus improving the etching uniformity of the wafer edge. The entire process allows for real-time testing and calibration of the magnetic field during the process, without opening the process chamber. Attached Figure Description
[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without any creative effort.
[0023] Figure 1 This is a schematic diagram of the structure of a process chamber provided in an embodiment of this application; Figure 2 This is a schematic diagram showing the distribution of multiple magnetic field detection elements at the edge of the lower electrode assembly, as provided in an embodiment of this application. Figure 3 This is a schematic diagram of the distribution of multiple edge coils provided in an embodiment of this application; Figure 4 yes Figure 1 A magnified structural diagram of part A in the middle; Figure 5 This is a schematic flowchart of a method for controlling a process chamber provided in an embodiment of this application; Figure 6 yes Figure 5 A control logic diagram of a control method; Figure 7 This is a schematic diagram of the control flow of a main area coil assembly provided in an embodiment of this application; Figure 8 This is a schematic diagram of the control flow of an edge coil assembly provided in an embodiment of this application; Figure 9 yes Figure 8 A schematic diagram of the first specific calibration process for the control method.
[0024] The realization of the objectives, functional features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation
[0025] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.
[0026] For ease of description, the following embodiments are all illustrated using an orthogonal space defined by a horizontal plane and a vertical direction. This premise should not be construed as a limitation of this application.
[0027] Please see Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of a process chamber provided in an embodiment of this application. Figure 2 This is a schematic diagram of the distribution of multiple magnetic field detection elements on the edge of the lower electrode assembly according to an embodiment of this application. The process chamber 100 may include: an upper electrode assembly 10, a lower electrode assembly 20, multiple magnetic field detection elements 30, and a magnetic field control unit 40.
[0028] The lower electrode assembly 20 is disposed below the upper electrode assembly 10. All magnetic field detection elements 30 are spaced apart along the edge of the lower electrode assembly 20. The magnetic field detection elements 30 are used to detect magnetic field strength. For example, the magnetic field detection elements 30 can be Hall effect devices. The magnetic field control unit 40 is disposed above the upper electrode assembly 10. The magnetic field control unit 40 includes a main region coil assembly 41 and an edge coil assembly 42. The main region coil assembly 41 includes at least one main coil, for example, one main coil or multiple main coils. When the main region coil assembly 41 includes multiple main coils, the multiple main coils are sequentially nested along the radial direction of one of the main coils. The multiple main coils can be coaxially arranged. The figure only shows two main coils 411 and 412 as examples. The edge coil assembly 42 includes multiple edge coils, each corresponding to one of the multiple magnetic field detection elements 30. The multiple edge coils are spaced apart around the main region coil assembly 41 in the circumferential direction of the main coils, that is, the multiple edge coils are arranged in a circle in the circumferential direction and surround the outermost main coil, such as... Figure 3 As shown, Figure 3 This is a schematic diagram of the distribution of multiple edge coils provided in an embodiment of this application. The diagram shows 18 edge coils Ci (i=1,2,3,...,18), which are evenly spaced along the circumference of the main coil 412. 18 field detection elements 30 are correspondingly provided. For example, each field detection element 30 can be located directly below the corresponding edge coil.
[0029] In this embodiment, the main area coil assembly 41 of the magnetic field control unit 40 in the process chamber is used to provide a magnetic field above the lower electrode assembly 20. Since multiple magnetic field detection elements 30 are spaced along the edge of the lower electrode assembly 20, each magnetic field detection element 30 can detect the magnetic field strength at the corresponding position. Furthermore, since the magnetic field control unit 40 also includes multiple edge coils, which are spaced around the main area coil assembly 41 in the circumferential direction of the main coil, when the magnetic field strength detected by a certain magnetic field detection element 30 is too large or too small, magnetic field compensation can be performed by adjusting the current or voltage of the edge coil corresponding to the magnetic field detection element 30. This can improve the uniformity of the plasma at the wafer edge, thereby improving the etching uniformity of the wafer edge.
[0030] In practical applications, the magnetic field strength data detected by the magnetic field detection element 30 can be directly read, and the unevenness of the magnetic field generated by the main coil at certain locations can be finely adjusted by adjusting the current or voltage of the edge coil. The entire process can be performed in real time during the process to test and calibrate the magnetic field without opening the process chamber.
[0031] In one embodiment, the process chamber may further include a controller 50, which can adjust the current or voltage of the main coil and the edge coil according to the detected magnetic field strength to perform magnetic field compensation, thereby realizing the automated adjustment of the magnetic field control unit 40.
[0032] In one embodiment, see Figure 2 and Figure 4 , Figure 4 yes Figure 1 The enlarged structural diagram of section A shows that the lower electrode assembly 20 may include a support structure 21 and a focusing ring 22, with the focusing ring 22 surrounding the outside of the support structure 21. All magnetic field detection elements 30 can be built into the focusing ring 22, or they can be placed inside the support structure 21; this is not limited here.
[0033] Optionally, when all magnetic field detection elements 30 are built into the focusing ring 22, the bottom of the focusing ring 22 is provided with multiple first through holes 221 corresponding to the multiple magnetic field detection elements 30. The supporting structure 21 is provided with channels 201 corresponding to each of the first through holes 221. The controller 50 is connected to the magnetic field detection elements 30 through the channels 201 and the first through holes 221. The first through holes 221 and the channels 201 can be used for cable 51 routing, such as... Figure 1 The dashed line indicates the connection between the magnetic field detection element 30 and the controller. For example, the focusing ring 22 may also integrate a heating structure to heat the edge region of the wafer; for instance, the focusing ring 22 may include, from top to bottom, a ceramic layer, a heating layer, and an aluminum substrate layer.
[0034] As an example of a load-bearing structure 21, please continue reading. Figure 1 and Figure 4 The supporting structure 21 may include: an electrostatic chuck 211, a first interface disk 212, a support ring 213, and a second interface disk 214. All magnetic field detection elements 30 can be built into the edge of the electrostatic chuck 211. The top of the electrostatic chuck 211 is provided with a boss, forming a convex structure, and a focusing ring 22 is arranged around the outside of the boss. The electrostatic chuck 211 has multiple second through holes 2111 that communicate with the first through hole 221 one by one. The first interface disk 212 is disposed on the lower surface of the electrostatic chuck 211, and the first interface disk 212 has multiple third through holes 2121 that communicate with the second through holes 2111 one by one. The first interface disk 212 can be made of insulating materials such as ceramic. The support ring 213 is disposed on the lower surface of the first interface disk 212, and the support ring 213 has multiple fourth through holes 2131 that communicate with the third through holes 2121 respectively. The support ring 213 can also be made of insulating materials such as ceramic. The second interface plate 214 is disposed on the lower surface of the support ring 213, and the second interface plate 214 can be made of metal materials such as aluminum.
[0035] The electrostatic chuck 211, the first interface disk 212, the support ring 213, and the second interface disk 214 are stacked sequentially. The second through hole 2111, the third through hole 2121, and the fourth through hole 2131 form a channel 201, each channel 201 corresponding to and connected to the first through hole 221 of the focusing ring 22. For improved sealing between different layers, please refer to [further details needed]. Figure 4 Furthermore, sealing rings 202 can be provided between the focusing ring 22 and the electrostatic chuck 211, between the electrostatic chuck 211 and the first interface disk 212, and between the first interface disk 212 and the support ring 213 to seal the channel 201.
[0036] By embedding the magnetic field detection element 30 into the focusing ring 22 and setting a sealing ring 202 between each layer of components, it is possible to prevent plasma from entering the channel 201 and causing corrosion to each component.
[0037] This application also provides a method for controlling a process chamber as described in the above embodiments, such as... Figure 5 As shown, the control method may include: S10. Adjustment of the main coil assembly 41: Based on the first magnetic field strength B1 measured by the multiple magnetic field detection elements 30, adjust the current or voltage of the main coil assembly 41 to make the average value of the multiple first magnetic field strengths equal. 1. It falls within the first preset range.
[0038] To improve plasma uniformity, a magnetic field control unit 40 is provided in the process chamber of this application. The size and density of plasma in the wafer edge area are adjusted by the magnetic field control unit 40 to make the etching rate of the wafer edge uniform.
[0039] For example, the main coil assembly 41 of the magnetic field control unit 40 can be turned on first, and each magnetic field detection element 30 can then measure the first magnetic field strength B1 at the location of that magnetic field detection element 30. i (B1) i B1 represents the first magnetic field strength detected by the i-th magnetic field detection element 30. i For example, in the embodiments of this application (i=1,2,3,...,18), then all first magnetic field strengths B1 can be calculated. i mean 1. Preset a first preset range [B1min, B1max], where B1min represents the lower limit of the first preset range, and B1max represents the upper limit of the first preset range. The first preset range can be the range of magnetic field strength required during the process. If all first magnetic field strengths B1 i mean If the magnetic field strength B1 exceeds the first preset range, the current or voltage of the main coil assembly 41 is adjusted to ultimately make all the first magnetic field strengths B1 equal. i mean 1 falls within the first preset range, i.e., B1min ≤ 1 ≤ B1max. Wherein, all first magnetic field strengths B1 i mean 1 equals all first magnetic field strengths B1 i The sum divided by the total number of magnetic field detection elements, for example, in the embodiments of this application, i=1,2,3,...,18, all first magnetic field strengths B1 i mean 1 = (B11 + B12 + ... + B1) 18 ) / 18. S20, Edge coil assembly 42 adjustment: Based on the first magnetic field strength B1 measured by multiple magnetic field detection elements 30 i Adjust the current or voltage of the edge coil assembly 42 to make the multiple first magnetic field strengths B1 i All fall within the first preset range.
[0040] By adjusting the main region coil assembly 41, the average magnetic field strength of the main region coil assembly 41 can be increased. 1. Adjusting to the first preset range does not guarantee that all first magnetic field strengths B1 i The plasma is uniform among themselves, thus making it impossible to guarantee the circumferential uniformity of the plasma at the wafer edge. At this point, the first magnetic field strength B1 measured by each magnetic field detection element 30 can be used as a reference.i And within a first preset range, adjust the current or voltage of each edge coil Ci to make each first magnetic field strength B1 i All fall within the first preset range, i.e., B1min≤B1≤B1max.
[0041] This embodiment allows adjustment of the current or voltage of the main coil assembly 41, so that the first magnetic field strength B1 measured by all magnetic field detection elements 30 can be adjusted. i mean If the magnetic field strength falls within the first preset range, the average magnetic field strength at the wafer edge will conform to the first preset range. However, there may be problems such as local magnetic fields being too large or too small and uneven. In this embodiment, the current or voltage of each edge coil can be adjusted to ensure that the first magnetic field strength B1 measured by all magnetic field detection elements 30 is within the first preset range. i All values fall within the first preset range, enabling precise local adjustment of the magnetic field generated by the main coil at certain locations by regulating the current or voltage of the edge coils. The entire process allows for real-time testing and calibration of the magnetic field during manufacturing, eliminating the need to open the process chamber and reducing labor costs.
[0042] Please see Figure 6 , Figure 6 yes Figure 5 A control logic diagram of the control method first adjusts the main region coil assembly 41, when all the first magnetic field strengths B1 i mean When 1 < B1min, the current or voltage of the main coil assembly 41 is increased. When 1 > B1max, the current or voltage of the main coil assembly 41 is reduced to eventually reduce the average value. 1 falls within the first preset range, i.e., B1min ≤ 1≤B1max.
[0043] After the main coil assembly 41 is adjusted, the first magnetic field strength B1 detected by each magnetic field detection element at the current moment is used as the basis for the adjustment. i Then adjust the edge coil assembly 42 to any first magnetic field strength B1 i When B1 i When B1 < B1min, the current or voltage of the edge coil corresponding to the magnetic field detection element 30 is increased; when B1 > B1max, the current or voltage of the edge coil corresponding to the magnetic field detection element 30 is decreased. This is achieved by adjusting the first magnetic field strength B1 for all... i The compensation ultimately makes all the first magnetic field strengths B1 i All fall within the first preset range, i.e., B1min < B1 i <B1max, thus the magnetic field adjustment is complete.
[0044] It should be noted that in the process chamber of each embodiment of this application, the main area coil assembly 41 may include one, two or more main coils arranged in sequence. The specific number is not particularly limited. According to the inventive concept of this application, the magnetic field uniformity at the edge of the wafer can be improved by adjusting the current or voltage, thereby improving the uniformity of plasma distribution.
[0045] The following description uses the example of the main coil assembly 41 having two main coils to further illustrate the specific adjustment method. The two main coils are: a first main coil 411 and a second main coil 412 surrounding the first main coil 411. In the above embodiment, when... When 1 < B1min, the current or voltage of the first main coil 411 can be increased, the current or voltage of the second main coil 412 can be increased, or both the current or voltage of the first main coil 411 and the second main coil 412 can be increased simultaneously. Similarly, when... When 1 > B1max, the current or voltage of the first main coil 411 and / or the second main coil 412 can be reduced.
[0046] Please see Figure 7 , Figure 7 This is a schematic diagram of the control flow of a main region coil assembly provided in an embodiment of this application. The control flow may include: S111. Turn on the first and second main coils to acquire multiple first magnetic field strengths B1 measured by all current magnetic field detection elements. i And calculate all first magnetic field strengths B1 i mean 1. [The following appears to be a separate, unrelated sentence:] Will 1. Compare with the preset first preset range [B1min, B1max]; like If 1 < B1min, it indicates that the actual magnetic field strength is too small, and S112 can be executed in this case.
[0047] like If 1 > B1 max, it indicates that the actual magnetic field strength is too large, and S117 can be executed at this time.
[0048] If B1min≤ If 1 ≤ B1max, then the adjustment of the main coil assembly ends.
[0049] S112. Obtain multiple second magnetic field strengths B2 measured by all magnetic field detection elements when only the first main coil is turned on. i Calculate the strength of all second magnetic fields B2 i mean 2.
[0050] Will 2. Compare with the preset second preset range [B2min, B2max], which is the range set for the first main coil.
[0051] like If 2 > B2max, then execute S113.
[0052] like If 2 ≤ B2max, then execute S114.
[0053] S113. Increase the current or voltage of the second main coil.
[0054] It should be noted that each first magnetic field strength B1 i This can be viewed as the superposition of the magnetic fields generated by the first and second main coils at corresponding positions, when all the first magnetic field strengths B1 i The mean of the total magnetic field (abbreviated as the mean of the total magnetic field). 1 is too small, while the second magnetic field strength B2 generated by the first main coil at all positions is too small. i mean If the value of 2 is too large, the strength of the first magnetic field B1 can be increased by increasing the current or voltage of the second main coil. i mean 1 is more reasonable, avoiding increasing the strength of the second magnetic field. B2 i lead to 2. It exceeds the second preset range by more.
[0055] S114. Obtain multiple third magnetic field strengths B3 measured when only the second main coil is turned on. i Calculate all third magnetic field strengths B3 i mean 3.
[0056] exist 1 < B1min, and 2 < B2max, 3. Compare with the preset third preset range [B3min, B3max], which is the range set for the second main coil.
[0057] like If 3 > B3max, it indicates that the average magnetic field of the second main coil is... 3 has exceeded the upper limit and is too large. At this point, the average total magnetic field value needs to be increased. 1, and Since 2 ≤ B2max, it is more reasonable to increase the current or voltage of the first main coil, so S115 is executed.
[0058] Otherwise, execute S116, that is... 3. The upper limit B3max was not exceeded. 3≤B3max), 2. If the upper limit B2max is not exceeded, the current or voltage of the first main coil and the second main coil can be increased at the same time to avoid exceeding the upper limit by adjusting only one of them too much.
[0059] S115. Increase the current or voltage of the first main coil.
[0060] S116. Simultaneously increase the current or voltage of the first main coil and the second main coil.
[0061] S117, if If 2 < B2max, then reduce the current or voltage of the second main coil.
[0062] Continuing from S111, when When 1 > B1 max, if 2≤B2max, meaning that the mean of the total magnetic field is... 1. If the value exceeds the upper limit, it needs to be reduced, and the average magnetic field of the first main coil needs to be adjusted. When the voltage is below the lower limit, it is more reasonable to reduce the current or voltage of the second main coil to avoid reducing the average magnetic field of the first main coil. 2. Make it too small.
[0063] S118, if 2 > B2max, and If 3 ≤ B3max, then reduce the current or voltage of the first main coil.
[0064] like 1 > B1 max, 2 > B2max, and 3≤B3max, meaning the mean of the total magnetic field 1. If the value exceeds the upper limit, it needs to be reduced, and the average magnetic field of the first main coil needs to be adjusted. 2. Exceeding the upper limit, the average magnetic field of the second main coil 3. When the voltage is below the lower limit, the current or voltage of the first main coil should be reduced.
[0065] S119, if 3 > B3max, simultaneously reducing the current or voltage of the first and second main coils.
[0066] Continuing from S118, if 1 > B1 max, 2 > B2max, and 3 > B3max, meaning the mean of the total magnetic field. 1. If the value exceeds the upper limit, it needs to be reduced, and the average magnetic field of the first main coil needs to be adjusted. 2. Exceeding the upper limit, the average magnetic field of the second main coil When 3 also exceeds the upper limit, the current or voltage of the first main coil and the second main coil can be reduced simultaneously.
[0067] The above control methods can be summarized in Table 1 below.
[0068] Table 1 Control methods for the main coil assembly under different operating conditions
[0069] Please see Figure 8 , Figure 8 This is a schematic diagram of the control flow of an edge coil assembly provided in an embodiment of this application. The control flow may include, if the average value of multiple first magnetic field strengths If the value falls within the first preset range, at least one round of calibration will be performed until the requirements are met; each round of calibration includes: S211. Obtain the current magnetic field strength B1 detected by each magnetic field detection element 30. i .
[0070] After the main coil assembly 41 is calibrated, all current magnetic field strengths B1 i mean 1. Satisfies B1min≤ 1 i ≤B1max, needs to be based on the current magnetic field strength B1 detected by each magnetic field detection element 30. i This further confirms the uniformity of the magnetic field strength at the wafer edge in the circumferential direction.
[0071] S212, If the magnetic field strength B1 detected by each magnetic field detection element is currently... i If all values are within the first preset range, then the requirement is met.
[0072] S213, If any current magnetic field strength B1 i If the magnetic field strength is not within the first preset range, the current or voltage of the edge coil corresponding to the magnetic field detection element 30 is adjusted so that the current magnetic field strength B1 detected by the magnetic field detection element 30 is adjusted. i It falls within the first preset range.
[0073] If B1min≤B1 i When ≤B1max, it means that all magnetic field strengths B1 i The requirements are met. If any current magnetic field strength B1 i If the magnetic field strength is not within the first preset range, the current or voltage of the edge coil corresponding to the magnetic field detection element 30 is adjusted so that the current magnetic field strength B1 detected by the magnetic field detection element 30 is adjusted. i It falls within the first preset range.
[0074] For example, for a certain edge coil Ci, when the current magnetic field strength B1 detected by the magnetic field detection element 30 corresponding to the edge coil Ci is... i If the current magnetic field strength B1 is less than B1min, then the current magnetic field strength B1 needs to be adjusted. i To perform positive compensation, the edge coil Ci can be turned on and a current in the same direction as the main coil can be applied. When B1 i When the value is greater than B1max, then the current magnetic field strength B1 needs to be adjusted. i To perform negative compensation, the edge coil can be turned on and a current in the opposite direction to that of the main coil can be applied.
[0075] Since the magnetic field generated by the post-adjusted edge coil affects the magnetic field strength detected by the magnetic field detection element 30 corresponding to the edge coil that has been adjusted previously, after iterating through the adjustments of the current or voltage of all edge coils, it is necessary to further determine the current magnetic field strength B1 detected by all magnetic field detection elements 30. i Check if it is still within the first preset range. If not, repeat the above steps for a second round of calibration until the requirements are met.
[0076] Specifically, this application provides a first specific calibration method, such as... Figure 9 As shown, the current magnetic field strength B1 detected by the magnetic field detection element 30 corresponding to all edge coils Ci (i=1,2,3,...) is first obtained. i Then, for each current magnetic field strength B1 i Compare with the first preset range. If B1 i If the magnetic field exceeds the first preset range, the edge coil corresponding to the magnetic field detection element 30 is activated for compensation. Specifically, a positive current can be applied for positive compensation, or a negative current can be applied for negative compensation, until the current or voltage of all edge coils is adjusted. Then, the current magnetic field strength B1 detected by all magnetic field detection elements 30 is further determined. i Check if it is still within the first preset range. If not, repeat the above steps for the next round of calibration.
[0077] In one embodiment, for the adjustment of the current or voltage of the same magnetic field detection element 30, the adjustment range in the next calibration round is smaller than the adjustment range in the previous calibration round. By gradually reducing the adjustment range, rapid convergence can be achieved, reducing the number of calibration rounds.
[0078] In one embodiment, during the first round of calibration, the change in the first magnetic field strength Bi, ΔBi, caused by adjusting the current or voltage of any magnetic field detection element 30, satisfies the following relationship: ΔBi = {|Bi - B1min|, |Bi - B1max|}min, where B1min and B1max are the lower and upper limits of the first preset range, respectively. That is, the adjustment is made towards the endpoint closer to which the first magnetic field strength Bi is closer to the upper or lower limit of the first preset range. In the next round of calibration, the first magnetic field strength B1... i The change value is the first magnetic field strength B1 in the previous calibration. i By continuously fine-tuning the current of all edge coils, half of the change value can eventually be made to detect the current magnetic field strength B1 of all magnetic field detection elements 30. i All fall within the first preset range, thereby calibrating the magnetic field at the edge of the wafer uniformly.
[0079] The following example uses a main coil assembly with only one main coil and an edge coil assembly with 18 edge coils (Ci~C18, see reference). Figure 3 Taking 1A current as an example, the first preset range of magnetic field strength corresponding to the main coil is [2.5, 2.6], unit: GS.
[0080] The main coil is turned on and a current of 1A is applied. The magnetic field strength B1 is detected in real time by 18 magnetic field detection elements. i As shown in Table 1.
[0081] Table 1 Magnetic field strength at a current of 1A
[0082] All first magnetic field strengths B1 i average 1 represents 2.3GS, which is compared with the first preset range [2.5, 2.6]. The current is less than the lower limit of the first preset range, therefore the main coil current is increased. When the main coil current increases to 1.1A, the magnetic field strength detected in real time by the 18 magnetic field detection elements 30 is shown in Table 2. Table 2 Magnetic field strength at a current of 1.1 A
[0083] After adjusting the main coil, the average magnetic field strength detected by the 18 magnetic field detection elements 30 is 2.5GS, which meets the first preset range (2.5, 2.6). At this point, the main coil calibration is stopped, and the edge coils are started for calibration.
[0084] First, determine if the magnetic field strength detected by the magnetic field detection element 30 corresponding to edge coil C1 is within the first preset range. If it is, skip C1 and proceed to the judgment of C2, and so on. In this example, we can see that C1 to C3 all meet the requirements. The magnetic field strength at C4 is less than 2.5GS. At this point, C4 can be turned on to apply a current to positively compensate for the magnetic field, increasing the current or voltage of edge coil C4 until the magnetic field strength detected by the magnetic field detection element 30 corresponding to C4 equals 2.5GS. Then, proceed to the judgment and calibration of the next edge coil. This process continues until all 18 edge coils in the first round have been calibrated. The magnetic field strengths detected by the 18 magnetic field detection elements after the first round of edge coil calibration are shown in Table 3.
[0085] Table 3. Magnetic field strength detected by 18 magnetic field detection elements after the first round of edge coil calibration.
[0086] After the first round of edge coil calibration, the second, third, ..., Nth rounds of edge coil calibration are performed according to the above method. The adjustment range of the current or voltage of the edge coil in the next round of calibration can be set to not exceed 0.5 times that of the previous round. After N rounds of calibration, until all 18 measured magnetic field strengths are within the first preset range, the magnetic field strengths detected by the 18 magnetic field detection elements after the Nth round of edge coil calibration are shown in Table 4.
[0087] Table 4 shows the magnetic field strength detected by the 18 magnetic field detection elements after the Nth round of edge coil calibration.
[0088]
[0089] This application provides a second specific calibration method for the edge coil, if any current magnetic field strength B1 i If the magnetic field strength is not within the first preset range, the current or voltage of the edge coil corresponding to the magnetic field detection element 30 is adjusted so that the current magnetic field strength B1 detected by the magnetic field detection element 30 is adjusted. i Falling into the first preset range, specifically including: S221, Based on all current magnetic field strengths B1 i The difference from the first preset range determines the magnetic field adjustment amplitude of each edge coil.
[0090] It is understandable that for any current magnetic field strength B1 i If B1 i If it is not within the first preset range, it is considered that there is a difference from the first preset range. At this time, it is necessary to determine its magnetic field adjustment amplitude in order to calibrate it into the first preset range.
[0091] The magnitude of the magnetic field adjustment is not limited, as long as the current magnetic field strength B1 is adjusted accordingly.i The convergence to the first preset range is sufficient. As an example, for any edge coil Ci, its magnetic field adjustment amplitude ΔB... i It can be defined as: ΔB i =B1 i -(B1max- B1min) / 2, B1 i The current magnetic field strength B1 generated by the edge coil Ci at the corresponding position. i .
[0092] S222. For any edge coil, based on the applied current or voltage and the magnetic field adjustment amplitude corresponding to the edge coil, establish a relationship between the magnetic field adjustment amplitude and the applied current or voltage of the edge coil.
[0093] It is understandable that for any edge coil Ci, adjusting it will cause a change in the detection value of the magnetic field detection element 30 corresponding to edge coil Ci. Adjusting other edge coils (such as Ci-1, Ci+1, etc.) will also cause a change in the magnetic field strength detected by the magnetic field detection element 30. With the distance remaining constant (after the arrangement of all edge coils is determined), it can be approximately assumed that the influence of the magnetic field generated by other edge coils on the detection value of the magnetic field detection element 30 corresponding to that edge coil is proportional. This fixed proportion can be determined in advance through experiments.
[0094] Therefore, for any edge coil Ci, based on the current or voltage applied to all edge coils and the magnetic field adjustment amplitude corresponding to that edge coil, a relationship can be established between the magnetic field adjustment amplitude and the current or voltage applied to all edge coils, resulting in i relationships. These i relationships include i unknowns, namely the magnitude of the current or voltage applied to each edge coil.
[0095] S223. Based on all the relationships, determine the current or voltage applied to each edge coil.
[0096] S224. Apply the corresponding current or voltage to each edge coil.
[0097] Based on the i relationships, the i unknowns can be solved, allowing us to calculate the magnitude of the current or voltage that should be applied to each edge coil. Then, based on the calculation results, the corresponding current or voltage is applied to each edge coil.
[0098] This calibration method can complete the calibration in one go, making the calibration more efficient.
[0099] For example, the above i relations are shown below: ΔB1= n1*f(C1)+ n2*f(C2)+ n3*f(C3)+……ni *f(C i ) ΔB2= n i *f(C1)+ n1*f(C2)+ n2*f(C3)+……n （i-1） *f(Ci); ΔB3= n （i-1） *f(C1)+ n i *f(C2)+ n1*f(C3)+……n （i-2） *f(Ci); ……, ΔBi= n2*f(C1)+ n3*f(C2)+……n i *f(C3)+n1*f(Ci); Wherein, ΔBi is the magnetic field adjustment amplitude of the edge coil Ci; n1 is the influence factor of the edge coil C1 on the detection result of the magnetic field detection element S1 corresponding to the edge coil C1; n2 is the influence factor of the edge coil C2, which is the first nearest neighbor on one side of the edge coil C1, on the detection result of the magnetic field detection element S1; n3 is the influence factor of the edge coil C3, which is the second nearest neighbor on one side of the edge coil C1, on the detection result of the magnetic field detection element S1; ..., n i The influence factor of the (i-1)th nearest neighbor edge coil Ci on the side of edge coil C1 on the detection result of the magnetic field detection element S1, where n1~ni are all known constants that can be determined in advance through experiments; f(C i ) represents the current magnetic field strength of the edge coil Ci.
[0100] f(C) can be calculated from the above i equations. i Then, deduce the current or voltage that should be applied to the edge coil Ci.
[0101] For other working principles and processes of the process chamber in this embodiment, please refer to the description of the control method in the foregoing embodiments of the present invention, which will not be repeated here.
[0102] The foregoing has provided a detailed description of a process chamber and control method provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. It should be noted that the descriptions of each embodiment in this application have different focuses; parts not described in detail in a particular embodiment can be referred to in the relevant descriptions of other embodiments.
[0103] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, components, features, and elements with the same names in different embodiments of this application may have the same meaning or different meanings, the specific meaning of which must be determined by its interpretation in that specific embodiment or further in conjunction with the context of that specific embodiment.
[0104] It should be further understood that the terms "comprising" or "including" indicate the presence of the stated features, steps, operations, elements, components, items, types, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, types, and / or groups. The terms "or," "and / or," and "comprising at least one of the following," as used in this application, can be interpreted as inclusive, or mean any one or any combination thereof. For example, "comprising at least one of the following: A, B, C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C," and similarly, "A, B, or C" or "A, B, and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C." Exceptions to this definition only occur when the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.
[0105] It should be understood that although the terms first, second, third, etc., may be used in this document to describe various types of information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this document, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the singular forms “a,” “an,” and “the” used in this document are intended to also include the plural forms, unless the context indicates otherwise.
[0106] It should be understood that the terms "top", "bottom", "upper", "lower", "vertical", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application.
[0107] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. The technical features of the technical solution of this application can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are also included within the patent protection scope of this application, as long as the combination of these technical features does not contradict each other.
Claims
1. A process chamber, characterized in that, include: Upper electrode assembly; The lower electrode assembly is disposed below the upper electrode assembly; Multiple magnetic field detection elements are spaced apart along the edge of the lower electrode assembly, and the magnetic field detection elements are used to detect the magnetic field strength. A magnetic field control unit is disposed above the upper electrode assembly. The magnetic field control unit includes a main region coil assembly and an edge coil assembly. The main region coil assembly includes one or more main coils, and the multiple main coils are sequentially nested along the radial direction of one of the main coils. The edge coil assembly includes multiple edge coils, each corresponding to one of the multiple magnetic field detection elements. The multiple edge coils are arranged at intervals around the main coil assembly in the circumferential direction of the main coil.
2. The process chamber according to claim 1, characterized in that, Also includes: A controller is used to adjust the current or voltage of the main coil and the edge coil according to the magnetic field strength.
3. The process chamber according to claim 2, characterized in that, The lower electrode assembly includes: Load-bearing structure; A focusing ring is disposed around the outer side of the load-bearing structure; The plurality of magnetic field detection elements are built into the focusing ring. The bottom of the focusing ring is provided with a first through hole corresponding to each of the plurality of magnetic field detection elements. The supporting structure is provided with a channel corresponding to each of the first through holes. The controller is connected to the magnetic field detection elements through the channel and the first through hole.
4. The process chamber according to claim 3, characterized in that, The load-bearing structure includes: An electrostatic chuck has a boss on the top, and a focusing ring is arranged around the outside of the boss. The electrostatic chuck has a plurality of second through holes that are connected to the first through hole one by one. The first interface disk is disposed on the lower surface of the electrostatic chuck, and the first interface disk is provided with a plurality of third through holes that communicate with the second through holes one by one; A support ring is disposed on the lower surface of the first interface disk, and the support ring is provided with a plurality of fourth through holes corresponding to and communicating with the third through hole; The second interface plate is disposed on the lower surface of the support ring; The second through hole, the third through hole, and the fourth through hole constitute the channel.
5. A control method for a process chamber as described in any one of claims 1-4, characterized in that, include: Main area coil assembly adjustment: Based on the first magnetic field strength measured by the plurality of magnetic field detection elements, adjust the current or voltage of the main area coil assembly so that the average value of the plurality of first magnetic field strengths falls within a first preset range; Edge coil assembly adjustment: Based on the first magnetic field strength measured by the plurality of magnetic field detection elements, adjust the current or voltage of the edge coil assembly so that the plurality of first magnetic field strengths all fall within the first preset range.
6. The control method according to claim 5, characterized in that, The main coil assembly includes a first main coil and a second main coil arranged around the first main coil; The steps for adjusting the main region coil assembly include: Turn on the first main coil and the second main coil to obtain the multiple first magnetic field strengths measured by the multiple magnetic field detection elements; If the average value of the plurality of first magnetic field strengths exceeds the first preset range, the current or voltage of the first main coil and / or the second main coil is adjusted so that the average value of the plurality of first magnetic field strengths falls within the first preset range.
7. The control method according to claim 6, characterized in that, Also includes: If the average value of the plurality of first magnetic field strengths is less than the lower limit of the first preset range, then increase the current or voltage of the first main coil and / or the second main coil. If the average value of the plurality of first magnetic field strengths is greater than the upper limit of the first preset range, then the current or voltage of the first main coil and / or the second main coil is reduced.
8. The control method according to claim 7, characterized in that, If the average value of the plurality of first magnetic field strengths is less than the lower limit of the first preset range, then the current or voltage of the first main coil and / or the second main coil is increased, specifically including: If the average value of the first magnetic field strength is less than the lower limit of the first preset range, then obtain the multiple second magnetic field strengths measured by the multiple magnetic field detection elements when only the first main coil is turned on. If the average value of the plurality of second magnetic field strengths is greater than the upper limit of the second preset range, then the current or voltage of the second main coil is increased.
9. The control method according to claim 8, characterized in that, Also includes: If the average value of the plurality of second magnetic field strengths is less than or equal to the upper limit of the second preset range, then obtain the plurality of third magnetic field strengths measured when only the second main coil is turned on, and compare the relationship between the average value of the plurality of third magnetic field strengths and the third preset range. If the average value of the plurality of third magnetic field strengths is greater than the upper limit of the third preset range, the current or voltage of the first main coil is increased; if the average value of the plurality of third magnetic field strengths is less than or equal to the upper limit of the third preset range, the current or voltage of the first main coil and the second main coil are increased simultaneously.
10. The control method according to claim 7, characterized in that, If the average value of the plurality of first magnetic field strengths is greater than the upper limit of the first preset range, then the current or voltage of the first main coil and / or the second main coil is reduced, specifically including: If the average value of the first magnetic field strength is greater than the upper limit of the first preset range, then obtain the multiple second magnetic field strengths measured by the multiple magnetic field detection elements when only the first main coil is turned on. If the average value of the plurality of second magnetic field strengths is less than or equal to the upper limit of the second preset range, then the current or voltage of the second main coil is reduced.
11. The control method according to claim 10, characterized in that, Also includes: If the average value of the plurality of second magnetic field strengths is greater than the upper limit of the second preset range, then the relationship between the average value of the plurality of third magnetic field strengths and the third preset range is compared. If the average value of the plurality of third magnetic field strengths is less than or equal to the upper limit of the third preset range, then the current or voltage of the first main coil is reduced; if the average value of the plurality of third magnetic field strengths is greater than the upper limit of the third preset range, then the current or voltage of both the first main coil and the second main coil are reduced simultaneously.
12. The control method according to any one of claims 5-11, characterized in that, The adjustment steps for the edge coil assembly include: If the average of the plurality of first magnetic field strengths falls within the first preset range, then at least one round of calibration is performed until the requirement is met; wherein each round of calibration includes: Obtain the current magnetic field strength detected by each magnetic field detection element; If all the current magnetic field strengths are within the first preset range, then the requirement is met. If any of the current magnetic field strengths is outside the first preset range, the current or voltage of the edge coil corresponding to the magnetic field detection element is adjusted so that the current magnetic field strength detected by the magnetic field detection element falls within the first preset range.
13. The control method according to claim 12, characterized in that, When adjusting the current or voltage of the same magnetic field detection element, the adjustment range in the next calibration is smaller than that in the previous calibration.
14. The control method according to claim 13, characterized in that, In the first round of calibration, the change in the first magnetic field strength Bi, ΔBi, caused by adjusting the current or voltage of any magnetic field detection element satisfies the following relationship: ΔBi = {|Bi - B1min|, |Bi - B1max|}min, where B1min and B1max are the lower and upper limits of the first preset range, respectively; and / or, The change in the first magnetic field strength in the next calibration is half the change in the first magnetic field strength in the previous calibration.
15. The control method according to claim 12, characterized in that, If any of the current magnetic field strengths is outside the first preset range, the current or voltage of the edge coil corresponding to the magnetic field detection element is adjusted so that the current magnetic field strength detected by the magnetic field detection element falls within the first preset range, specifically including: The magnetic field adjustment amplitude of each edge coil is determined based on the differences between the current magnetic field strength and the first preset range. For any of the aforementioned edge coils, based on the applied current or voltage and the magnetic field adjustment amplitude corresponding to the edge coil, a relationship is established between the magnetic field adjustment amplitude and the applied current or voltage of the edge coil. Based on all the relationships, determine the current or voltage supplied to each of the said edge coils; Apply a corresponding current or voltage to each of the edge coils.
16. The magnetic field calibration method according to claim 15, characterized in that, All the relations are: ΔB1= n1*f(C1)+ n2*f(C2)+ n3*f(C3)+……n i *f(C i ) ΔB2= n i *f(C1)+ n1*f(C2)+ n2*f(C3)+……n （i-1） *f(Ci); ΔB3= n （i-1） *f(C1)+ n i *f(C2)+ n1 *f(C3)+……n （i-2） *f(Ci); ……， ΔBi= n2*f(C1)+ n3*f(C2)+……n i *f(C3)+n1*f(Ci); Wherein, ΔBi is the magnetic field adjustment amplitude of the edge coil Ci; n1 is the influence factor of the edge coil C1 on the detection result of the magnetic field detection element S1 corresponding to the edge coil C1; n2 is the influence factor of the edge coil C2, which is the first nearest neighbor on one side of the edge coil C1, on the detection result of the magnetic field detection element S1; n3 is the influence factor of the edge coil C3, which is the second nearest neighbor on one side of the edge coil C1, on the detection result of the magnetic field detection element S1; ..., n i f(C) is the influence factor of the (i-1)th nearest neighbor edge coil Ci on the detection result of the magnetic field detection element S1. i ) represents the current magnetic field strength of the edge coil Ci.