Wafer position identification method and device in ion implanter
By using image acquisition and processing technology in the ion implanter, the position of the wafer on the electrostatic suction cup is solved, and the problem of lack of monitoring of the wafer placement position in the prior art is achieved, and the accurate identification of wafer position and improvement of product quality is achieved.
Patent Information
- Application Number
- CN202311776155.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-06-24
AI Technical Summary
During the chip transfer process of existing ion implantation machines, the relative position of the wafer on the electrostatic suction cup is lacking, resulting in abnormal placement of the wafer, insufficient electrostatic suction, falling and breaking, affecting product quality and equipment safety.
By using image acquisition and processing technology in the ion implanter, we define the judgment area based on the center point of the electrostatic suction cup, obtain the images of the electrostatic suction cup and the wafer, calculate whether the change in the characteristic data in the region exceeds the preset value, and then identify whether the position of the wafer is accurate.
Accurate identification of the position of the wafer on the electrostatic suction cup is achieved, production efficiency is improved, wafer scrapping rate is reduced, product quality and equipment reliability are improved.
Smart Images
Figure CN120199697A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor processing technology, and particularly to the positioning of semiconductor wafers. Background Art
[0002] Wafer position recognition technology refers to the technology of determining the position information of a wafer by scanning and analyzing the wafer. This technology is mainly applied in the semiconductor manufacturing process to ensure the accurate position and orientation of the wafer during processing, thereby ensuring the safety and stability of the product.
[0003] However, as Figure 12A shown, during the wafer transfer process in the cavity of a conventional ion implanter device, only a laser sensor is used to detect whether there is a wafer during the wafer transfer by the left vacuum arm and the right vacuum arm. After the wafer is placed on the electrostatic chuck, the electrostatic force is used to adsorb the wafer and start the implantation. There is no monitoring at all of the relative position where the wafer is placed on the electrostatic chuck. Due to the lack of effective monitoring means. If the wafer 80 is placed in the correct position on the electrostatic chuck 70, for example Figure 12B the position shown, the subsequent process can proceed accurately. When the wafer 80 is placed in an abnormal position on the electrostatic chuck 70, for example Figure 12C the position shown, during the running process, due to the abnormal position, there will be a situation where the electrostatic suction force of the electrostatic chuck 70 is insufficient, and the wafer 80 will fall and break, for example Figure 12D shown, thus damaging the product and contaminating the cavity. In addition, after the implantation process is completed, the electrostatic chuck 70 rotates from a vertical position to a horizontal position. When the ejector pin lifts the wafer 80, it will tilt, slide, or the vacuum arm 90 will knock off the wafer when picking up the wafer, as Figure 12E shown.
[0004] The current solution to the above problems is: Before implantation, the left or right vacuum arm 90 takes out the wafer 80 from the wafer cassette (left, right), and the vacuum arm 90 emits laser light from the side and irradiates the reflector 91 as Figure 13A shown, and the reflected light is received by the receiver on the vacuum arm. When there is a wafer, because diffuse reflection occurs on the surface of the wafer 80, the light intensity received by the receiver decreases significantly, that is, it is judged that there is a wafer. After the implantation is completed, the vacuum arm 90 transfers the wafer 80 from the electrostatic chuck 70 to the wafer cassette, and four laser sensors 61 on the wafer cassette detect the position of the wafer on the wafer cassette. A laser emitter is arranged at the top to emit laser light, and the four laser sensors 61 below detect. When the sensor reaches a threshold value, for example 100, it is considered that the position of the wafer 80 is normal; if the value is less than this threshold value, it is considered that the wafer position is offset, and the warning light will be highlighted.
[0005] The above technical solution does not evaluate the position when the robotic arm 90 transfers to the electrostatic chuck 70 and places on the electrostatic chuck 70. However, there are some mechanisms to respond to serious positioning deviations of the wafer. For example: in the mainstream ion implanter, the transfer accuracy of the vacuum arm is relatively high, and abnormal wafer placement occurs occasionally. And it is related to the relative position of the wafer with a missing corner in the wafer cassette after the previous process is completed.
[0006] The position when transferring to the electrostatic chuck 70 may be abnormal, resulting in a decrease in the electrostatic chuck current and the machine tool alarming. In addition, when the software recognizes that the wafer position is offset, the process will be stopped. It will return to the wafer rack to reduce risks such as wafer dropping caused by continuous implantation. However, when the electrostatic chuck is in the vertical state, the wafer will directly drop and cannot be remedied; it cannot be normally transferred back, and the equipment needs to be powered off and the cavity opened for processing, resulting in the wafer dropping without adsorption force. Moreover, when the electrostatic chuck is placed horizontally and alarms, the equipment manually adjusts the position of the robotic arm to try to transfer the wafer back. If it is ineffective, the cavity needs to be opened to manually take out the wafer, but it may still cause the wafer to be scrapped. Summary of the Invention
[0007] The purpose of the present application is to provide an ion implanter machine tool that can identify and judge the relative position of the wafer placed on the electrostatic chuck, so as to accurately determine the position of the wafer.
[0008] Another purpose of the present application is to provide a method and device that can quickly and accurately identify the edge position of the wafer. Preferably, the method and device can be applicable to various wafer shapes and sizes, and / or can effectively avoid the influence of manual intervention on the recognition result.
[0009] To this end, some embodiments of the present application provide a method for identifying the position of a wafer in an ion implanter, which includes the steps of: defining a judgment area based on the center point of the electrostatic chuck; obtaining a second image including the electrostatic chuck and the wafer thereon; calculating whether the change of at least one feature data of the second image in the judgment area from the first radial dimension of the first boundary of the judgment area to the second radial dimension of the second boundary exceeds a preset value; and identifying whether the position of the wafer is accurate according to the judgment result.
[0010] In some embodiments, the defining a judgment area based on the center point of the electrostatic chuck specifically includes collecting a top view image of the electrostatic chuck as a first image; finding the center point of the electrostatic chuck in the first image; defining an annular area at a first distance from the center point with the position where the center point is located as the center, and taking a part or the whole of the annular area as the judgment area; wherein, the position of the annular area is determined based on the size of the wafer to ensure that when the wafer position is correct, the edge of the wafer falls within the annular area.
[0011] In some embodiments, obtaining a second image including the electrostatic chuck and the wafer thereon further includes preprocessing the second image.
[0012] Calculating whether a change of at least one feature data of the second image within the judgment region from a first radial dimension at a first boundary of the judgment region to a second radial dimension at a second boundary exceeds a preset value includes providing at least one judgment element within the judgment region; calculating an obvious change in the gray value of pixels from the smaller radial dimension to the larger radial dimension for each judgment element; and taking the judgment results of all judgment elements as the judgment result of the judgment region.
[0013] In some embodiments, the judgment element is a line, strip, section, or entire annular region formed by pixels between a first boundary with a smaller radial dimension and a second boundary with a larger radial dimension of the judgment region.
[0014] In some embodiments, the plurality of judgment elements are uniformly distributed in a plurality of circumferential directions of the judgment region.
[0015] In some embodiments, if the judgment results for all judgment elements are that there is an obvious change in the gray value of pixels, it is determined that the position of the wafer on the electrostatic chuck is correct, and if there is a judgment result for a judgment object that there is no obvious change in the gray value of pixels, it is determined that the position of the wafer on the electrostatic chuck is incorrect.
[0016] In some embodiments, a plurality of sections are respectively taken as judgment elements within the judgment region; each judgment element is further divided into a plurality of parallel strip-shaped sub-judgment elements, and each strip-shaped sub-judgment element is basically in the shape of a parallelogram.
[0017] In some embodiments, judging whether there is an obvious change in the gray value includes judging whether there is a mutation by taking the derivative of the gray value of pixels in the judgment element with respect to its position.
[0018] In some embodiments, a binarization operation is performed on the gray value of the second image within the judgment region to judge whether there is an obvious change in the gray value.
[0019] In some embodiments, a judgment region gradient is set, that is, a plurality of judgment regions with different radial dimensions; when it is judged that there is a mutation in the gray value in the second image with a first judgment region of a certain radial dimension, then a judgment region with a smaller radial dimension is used to continue to judge whether there is a mutation in the gray value in the second image, so as to determine whether there is a small amount of wafer offset.
[0020] In some embodiments, the judgment region is defined based on the center point or outer contour of the electrostatic chuck.
[0021] Some embodiments of the present application also provide a wafer position recognition device in an ion implanter, which includes an image acquisition unit and a processing unit. The image acquisition unit is configured to acquire the first image and / or the second image. The processing unit includes a processor and a memory. The memory stores a computer program, and the processor is configured to run the computer program to execute the wafer position recognition method in any one of the above claims.
[0022] Some embodiments of the present application also provide a wafer position recognition device in an ion implanter, which includes a processor and a memory. The memory stores a computer program, and the processor is configured to run the computer program to execute the wafer position recognition method in any one of the above claims.
[0023] The beneficial effects of the present application are as follows: In some embodiments, the wafer position recognition technology analyzes the wafer surface image obtained, and determines whether there is an obvious offset of the wafer on the electrostatic chuck, thereby improving production efficiency, reducing production costs, reducing the scrapping of wafers caused by relative position problems in the cavity, and improving product quality and reliability. In some embodiments, by providing the gradient of the judgment area, the position of the wafer on the electrostatic chuck can be more accurately determined, so as to accurately locate the wafer position, ensure the uniformity of the ion implanter beam current within ±160 mm, improve the consistency between the center and the boundary of the wafer, and the performance between chips on one wafer. Description of the Drawings
[0024] Figure 1 is a flowchart of a wafer position recognition method in an ion implanter according to an embodiment of the present application;
[0025] Figure 2 is a flowchart of a method for recognizing a judgment area in an ion implanter according to an embodiment of the present application;
[0026] Figure 3 is a flowchart of a contour judgment step in a wafer position recognition method in an ion implanter according to an embodiment of the present application;
[0027] Figure 4 is a diagram showing the positional relationship between the wafer and the electrostatic chuck when it is determined that the wafer position is normal in a wafer position recognition method in an ion implanter according to an embodiment of the present application;
[0028] Figure 5 is a diagram showing the positional relationship between the wafer and the electrostatic chuck when it is determined that the wafer position is abnormal in a wafer position recognition method in an ion implanter according to an embodiment of the present application;
[0029] Figure 6Schematic diagram of the positional relationship between the image acquisition unit and the electrostatic chuck adopted by the wafer position recognition method in the ion implanter according to an embodiment of the present application;
[0030] Figure 7 Top view of the electrostatic chuck involved in the wafer position recognition method in the ion implanter according to an embodiment of the present application;
[0031] Figure 8 Schematic diagram of the positional relationship between the image acquisition unit, the wafer, and the electrostatic chuck adopted by the wafer position recognition method in the ion implanter according to an embodiment of the present application;
[0032] Figure 9 Schematic diagram of taking four orthogonal sections as judgment elements in the wafer position recognition method in the ion implanter according to an embodiment of the present application;
[0033] Figure 10 Is Figure 9 Schematic diagram of dividing one of the sections into strip-shaped sub-judgment elements;
[0034] Figure 11 Comparison diagram of calculation results of the edge of the wafer image existing and not existing in the same judgment element in the wafer position recognition method in the ion implanter according to an embodiment of the present application;
[0035] Figure 12A Schematic diagram of the transfer path of the wafer in the ion implanter in the prior art;
[0036] Figure 12B Schematic diagram of the normal state of the wafer at the electrostatic chuck position in the ion implanter in the prior art;
[0037] Figure 12C Schematic diagram of the abnormal state of the wafer at the electrostatic chuck position in the ion implanter in the prior art;
[0038] Figure 12D Schematic diagram of the state where the wafer slides off after the electrostatic chuck stands upright in the ion implanter in the prior art;
[0039] Figure 12E Schematic diagram of the inclined state of the wafer on the electrostatic chuck in the ion implanter in the prior art;
[0040] Figure 13A Schematic diagram of the structural principle of detecting the existence of the wafer by laser during the transfer of the vacuum arm in the prior art;
[0041] Figure 13B Schematic diagram of the principle of detecting the wafer position by the wafer holder in the prior art;
[0042] Figure 13CSchematic diagram of the state when the relative positions of the chamfers between wafers are normal in the prior art;
[0043] Figure 13D Schematic diagram of the state when the relative positions of the chamfers between wafers are abnormal in the prior art. Detailed implementation manners
[0044] The technical solutions in the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.
[0045] As used herein, the terms "about", "substantially", "essentially" are used to describe and account for small variations. When used in connection with an event or circumstance, the terms can refer to instances where the event or circumstance occurs precisely and instances where the event or circumstance occurs very nearly. For example, when used in connection with a numerical value, the terms can refer to a range of variation of plus or minus 10% of the numerical value, such as plus or minus 5%, plus or minus 0.5%, or plus or minus 0.05%. For example, if the difference between two numerical values is less than or equal to plus or minus 10% of the average value of the values, then the two numerical values can be considered to be "substantially" the same.
[0046] For ease of description, "first", "second", "third", etc. may be used herein to distinguish different components of a figure or a series of figures. "First", "second", "third", etc. are not intended to describe corresponding components.
[0047] In the present application, unless specifically specified or limited otherwise, the terms "arranged", "connected", "coupled", "fixed" and similar terms are used widely, and those skilled in the art can understand the above terms according to specific circumstances. For example, it can be a fixed connection, a detachable connection or an integrated connection; it can also be a mechanical connection or an electrical connection; it can also be a direct connection or an indirect connection through an intermediate structure; it can also be internal communication between two components.
[0048] The purpose of the present application is to identify whether the position of the wafer 80 on the electrostatic chuck 70 is accurate. For example, as Figure 4 shown, the wafer is in an accurate position on the electrostatic chuck, while Figure 5 shown, the position of the wafer on the electrostatic chuck is offset.
[0049] Figure 1 is a flowchart of a wafer position identification method according to an embodiment of the present application. Referring to Figure 1 , the method includes the steps:
[0050] Step S100, define a judgment area based on the center point of the electrostatic chuck. Specifically, it may be as follows Figure 2 shown, including step S101, collect a top view image of the electrostatic chuck as the first image. For example, use Figure 6 the device shown, that is, use a high-resolution camera, such as a 2K, 2K high-definition camera, to capture the original top view image of the electrostatic chuck 80 as the first image. The appearance of the first image is as Figure 7 shown; step S102, preprocess the first image: perform operations such as noise reduction, filtering, and enhancement on the collected original image of the electrostatic chuck to better identify the electrostatic chuck image features including the ejector pin positioning holes and the edge of the electrostatic chuck in the image; step S103, find the center point of the electrostatic chuck in the first image. For example, determine the position of the center point 704 of the electrostatic chuck through three ejector pin positioning holes 701, 702, and 703 in the identified first image features; step S104, define an annular area D1 at a first distance from the center point 704 with the position of the center point 704 as the center, and use a part or the whole of this annular area as the judgment area. It should be understood that the preprocessing is not necessary, but the image after preprocessing is more conducive to the identification of feature data.
[0051] Among them, the position of the annular area D1 is determined based on the size of the wafer, ensuring that when the position of the wafer is correct, the edge of the wafer falls within the annular area D1.
[0052] It should be understood that the judgment area is not limited to the above annular area. As long as the outer contour of the wafer in the correct position state is included in this judgment area, then it can be used as the judgment area for subsequent judgments.
[0053] Step S200, when the wafer exists on the electrostatic chuck, obtain a second image including the electrostatic chuck and the wafer thereon. The image acquisition scenario is as Figure 8 shown, and it can use Figure 6 the device shown; for example, this step may specifically include using a high-resolution camera to capture the original top view image of the electrostatic chuck and the wafer thereon as the second image; and preprocess the second image, including performing operations such as noise reduction, filtering, and enhancement on the collected second image to better identify the feature data of the image. The feature data is, for example, the gray value of each pixel in the image. It should be understood that the preprocessing is not necessary, but the image after preprocessing is more conducive to the identification of feature data.
[0054] Step S300, calculate whether the change of at least one feature data of the second image in the judgment area from the first radial dimension of the first boundary of the judgment area to the second radial dimension of the second boundary exceeds a preset value; for example, this step is as follows Figure 3 shown, and specifically may include: Step S301, provide at least one, preferably multiple judgment elements in the judgment area. The judgment elements may be, for example, a line, strip, or section formed by pixels between the first boundary with a smaller radial dimension and the second boundary with a larger radial dimension of the judgment area, or the entire annular area; for example, the judgment element may be a line connecting the first position P1 on the first boundary with a smaller radial dimension of the judgment area and the second position P2 on the second boundary with a larger radial dimension of the judgment area, such as a straight line; for another example, the entire annular area may be used as the judgment element; for another example, four mutually orthogonal sections within the annular area may be used as judgment elements respectively; then perform Step S302, that is, calculate the change in the gray value of the pixels from the smaller radial dimension to the larger radial dimension within the judgment element, such as whether there is an obvious change in the gray value of the pixels as the judgment result; here, an obvious change may be, for example, a gray value difference of 30% to 100%, such as a gray value difference of 50% to 100%.
[0055] Preferably, a plurality of judgment elements are evenly distributed in a plurality of circumferential directions of the judgment area, such as judgment elements evenly distributed in 32 circumferential directions, 16 circumferential directions, 8 circumferential directions, 4 circumferential directions, or 2 circumferential directions.
[0056] Step S400, determine whether the position of the wafer is accurate according to the judgment result. For example, if the judgment result for all judgment elements is that there is an obvious change in the gray value of the pixels, it can be judged that the position of the wafer on the electrostatic chuck is correct; if there is a judgment result for a judgment object that there is no obvious change in the gray value of the pixels, it is judged that the position of the wafer on the electrostatic chuck is incorrect and there is an offset. For another example, when three section judgment elements in the upper, lower, and right directions of the second image judge that there is an obvious change in the gray value of the pixels, while the section judgment element in the left direction judges that there is no obvious change in the gray value of the pixels, it is considered that the position of the wafer is incorrect and there is an offset.
[0057] In a preferred embodiment, an annular area at a certain distance from the center point 704 of the electrostatic chuck 70 is used as the first judgment area. For example, for a 150 mm wafer, the judgment area defined by the annular area D1 between the circles with diameters at positions 147 to 157 mm from the center position, and the circles with diameters of 147 mm and 157 mm are Figure 9 the two dashed circles.
[0058] To reduce the amount of graphic calculation, in the annular region D1, four sections with a length of 10 mm and a width of 50 mm are respectively taken as the first judgment element D11, the second judgment element D12, the third judgment element D13, and the fourth judgment element D14, that is Figure 9 the four shaded areas in the schematic diagram of
[0059] Each judgment element can be further divided to reduce the amount of graphic calculation. For example, the first judgment element D11 is divided into fifteen bar-shaped sub-judgment elements with a length of 10 mm and a width of 1.6 mm. For example, as Figure 10 shown by the dotted lines, the exemplary bar-shaped sub-judgment elements D111, D112, and D113. Each bar-shaped sub-judgment element is basically in the shape of a parallelogram. It can be noted that the bar-shaped sub-judgment elements are arranged at intervals, and the judgment results of these bar-shaped sub-judgment elements determine the judgment result of the first judgment element D11. For example, if several adjacent bar-shaped sub-judgment elements are judged to have no obvious change in gray value, it is considered that the first judgment element D11 has no obvious change, and thus the wafer position offset can be determined.
[0060] As Figure 11 shown. To determine whether there is an obvious change in the gray value, it can be judged whether there is a mutation by taking the derivative of the gray value of the pixels in the judgment element with respect to the position. If there is a mutation in the graph after derivation, it is considered that the wafer edge is detected in the judgment element and the wafer position is normal. If there is no mutation in the graph after derivation, it is considered that the wafer edge is not detected in the judgment element and the wafer position is abnormal.
[0061] As described above, it should be understood that the size of the bar-shaped sub-judgment elements in a section can be determined arbitrarily. In addition to using bar-shaped sub-judgment elements for judgment, linear sub-judgment elements can also be used for judgment.
[0062] To detect whether there is an obvious change in the gray value as described above, for example, the Canny algorithm can be used to search radially from the inside out for places where the threshold changes greatly in the judgment area. The binary operation can be performed on the image gray value in the judgment area, and the binary operation is performed with a preset threshold. For example, the binary value of the gray value in the above-mentioned 10-mm judgment area is used to qualitatively judge whether there is a mutation in the gray value.
[0063] It should be understood that the radial size of the judgment area can determine the judgment accuracy. For example, when the radial size of the judgment area is large, the judgment accuracy is low and small offsets of the wafer cannot be detected; while when the radial size of the judgment area is small, the judgment accuracy is high and small offsets of the wafer can be judged, but if it is too small, it may not be possible to quickly obtain a meaningful judgment result.
[0064] To this end, a judgment region gradient can be set, that is, multiple judgment regions with different radial dimensions, so as to increase the judgment accuracy. For example, when it is judged that there is a mutation in the gray value in the wafer image in the first judgment region with a certain radial dimension, then the second judgment region with a smaller radial dimension is used to judge whether there is a mutation in the gray value in the wafer image, so as to determine whether there is a small amount of wafer offset. The second judgment region with a smaller radial dimension and the first judgment region can share a boundary, and the radial dimension of the other boundary is larger or smaller. It is also possible to form a second region with a smaller radial dimension by changing the two boundaries of the first judgment region simultaneously.
[0065] It should be understood that the center point of the above-mentioned electrostatic chuck and the position of the judgment region based on this center point may need to be re-identified and set each time the ion implanter is debugged.
[0066] It should be understood that in addition to using the center point, the outer contour of the electrostatic chuck can also be used as a reference to define the judgment region.
[0067] The first image and / or the second image in the present application can be collected by any image acquisition unit, such as the high-definition cameras or cameras such as 2K and 4K described above. The method can be implemented by a computer program, and the computer program is stored in a memory, for example, and the processor runs the computer program to execute any one of the wafer position recognition methods in the ion implanter.
[0068] The technical content and technical features of the present application have been disclosed above. However, those skilled in the art may still make various substitutions and modifications that do not depart from the spirit of the present application based on the teachings and disclosures of the present application. Therefore, the protection scope of the present application should not be limited to the content disclosed in the embodiments, but should include various substitutions and modifications that do not depart from the present application and are covered by the claims of the present application.
Claims
1. A method for identifying the position of a wafer in an ion implanter, characterized in that: Including the steps: Step S100, defining a judgment area based on the center point of the electrostatic chuck; Step S200, obtaining a second image including the electrostatic chuck and the wafer thereon; Step S300, calculating whether the change of at least one feature data of the second image in the judgment area from the first radial dimension of the first boundary of the judgment area to the second radial dimension of the second boundary exceeds a preset value; Step S400, identifying whether the position of the wafer is accurate according to the judgment result.
2. The method for identifying the wafer position in the ion implanter according to claim 1, wherein: The specific steps of step S100 include Step S101, collecting a top view image of the electrostatic chuck as the first image; Step S103, finding the center point of the electrostatic chuck in the first image; Step S104, defining an annular area at a first distance from the center point with the position where the center point is located as the center, and taking a part or the whole of the annular area as the judgment area; wherein, the position of the annular area is determined based on the size of the wafer to ensure that when the position of the wafer is correct, the edge of the wafer falls within the annular area.
3. The method for identifying the position of a wafer in an ion implanter according to claim 1, characterized in that: The step S200 further includes preprocessing the second image.
4. The method for identifying the position of a wafer in an ion implanter according to claim 1, characterized in that: The specific steps of step S300 include Step S301, providing at least one judgment element in the judgment area; And Step S302, calculating the obvious change of the gray value of the pixels from the smaller radial dimension to the larger radial dimension for each judgment element; Step S303, taking the judgment results of all judgment elements as the judgment result of the judgment area.
5. The method for identifying the position of a wafer in an ion implanter according to claim 4, characterized in that: The judgment element is a line, strip, section or the entire annular area formed by the pixels between the first boundary with a smaller radial dimension and the second boundary with a larger radial dimension of the judgment area.
6. The method for identifying the position of a wafer in an ion implanter according to claim 4, wherein: The multiple judgment elements are evenly distributed in multiple circumferential directions of the judgment area.
7. The method for identifying the wafer position in the ion implanter according to claim 4, wherein: If the judgment results for all judgment elements are that there is an obvious change in the gray value of the pixels, it is judged that the position of the wafer on the electrostatic chuck is correct. If there is a judgment result of a judgment object that there is no obvious change in the gray value of the pixels, it is judged that the position of the wafer on the electrostatic chuck is incorrect.
8. The method for identifying the position of a wafer in an ion implanter according to claim 4, wherein: Taking multiple sections in the judgment area as judgment elements respectively; each judgment element is further divided into multiple parallel strip-shaped sub-judgment elements, and each strip-shaped sub-judgment element is basically in the shape of a parallelogram.
9. The method for identifying the position of a wafer in an ion implanter according to claim 4, wherein: Judging whether there is an obvious change in the gray value includes judging whether there is a mutation by taking the derivative of the gray value of the pixels in the judgment element with respect to its position.
10. The method for identifying the position of a wafer in an ion implanter according to claim 4, characterized in that: Performing a binarization operation on the gray value of the second image in the judgment area to judge whether there is an obvious change in the gray value.
11. The method for identifying the position of a wafer in an ion implanter according to claim 4, wherein: Setting judgment area gradients, that is, multiple judgment areas with different radial dimensions; when it is judged that there is a mutation in the gray value in the second image by a first judgment area with a certain radial dimension, then continue to use a judgment area with a smaller radial dimension to judge whether there is a mutation in the gray value in the second image, so as to determine whether there is a small amount of wafer offset.
12. The method for identifying the position of a wafer in an ion implanter according to claim 4, wherein: Defining the judgment area based on the center point or the outer contour of the electrostatic chuck.
13. Wafer position recognition device in an ion implanter, characterized in that: It includes an image acquisition unit and a processing unit. The image acquisition unit is configured to acquire the first image and / or the second image. The processing unit includes a processor and a memory. The memory stores a computer program. The processor is configured to run the computer program to execute the wafer position recognition method in the ion implanter according to any one of the above claims.
14. Wafer position recognition device in an ion implanter, characterized in that: It includes a processor and a memory. The memory stores a computer program. The processor is configured to run the computer program to execute the wafer position recognition method in the ion implanter according to any one of the above claims.