A wafer alignment method and related device

Abstract

The present invention relates to a wafer alignment method and related devices, the alignment method comprising: selecting a suitable alignment mark in a chip of a wafer to establish a work menu, and recording the position of the alignment mark and the size of the chip; using a pre-aligner to perform pre-alignment on the wafer, placing the wafer on a chuck, and recording the target angle of the wafer; performing rough alignment of the wafer; and performing fine alignment of the wafer. The wafer alignment method and related devices provided by the present invention improve the search efficiency of the alignment mark in the subsequent precise alignment step by performing rough alignment on the wafer; and perform precise alignment through the alignment mark at the far end of the wafer to improve the alignment accuracy of the wafer.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor measurement technology, and in particular to a wafer alignment method and related devices. Background Art

[0002] Optical Critical Dimension (OCD) measurement technology is widely used in the field of semiconductor chip manufacturing measurement, and is of great significance to the quality monitoring, process optimization, cost control, and yield improvement of semiconductor products. In semiconductor OCD detection equipment, usually only a specific area of ​​each chip (about 40umx40um) is detected. The chip is called Die, such as Figure 1 Each small square in the wafer is a small chip, and the content of each Die is exactly the same. There are fixed notches or cutting marks on the wafer, such as Figure 1 As shown, the black dot in the middle below is a gap. Since wafer inspection has high requirements for position positioning, it usually requires a plane accuracy error of micron level and an angle accuracy error within 0.01 degree. When the wafer is taken out of the wafer box, it is pre-aligned by the pre-aligner and transported to the inspection table. Due to the limited accuracy of the pre-aligner, the plane error is usually at the level of fifty microns and the angle error is usually within plus or minus 0.1 degrees. This accuracy cannot meet the inspection requirements, so it is necessary to accurately position it on the inspection table.

[0003] As a production equipment, the production performance efficiency of semiconductor measurement equipment directly affects the company's production capacity. Therefore, it is particularly important to control the time consumption of precise positioning on the test bench. If the wafer can be accurately positioned in a short time, the throughput of the equipment will be improved.

[0004] Semiconductor measurement equipment usually measures wafers in two steps: creating a recipe (work menu) and executing the recipe to measure the wafer. When creating the menu, the appropriate alignment mark is selected in the Die and the position is recorded, and the measurement area is selected and the position is recorded; when executing the recipe to measure the wafer, the alignment mark is first found and the wafer position is determined based on the alignment mark. This step is usually called wafer alignment, and then the wafer is moved to the predetermined measurement position and measured.

[0005] In order to ensure the wafer positioning accuracy, the general measurement currently used is to select a mark in the die that is far away from the wafer center for search and correct the wafer through two points. Figure 1 As shown, the steps are: Die in the center Figure 1 Find a specific mark in Die 1 in the middle and record its position A; the Die adjacent to the center Die is Figure 1Find the mark in Die 2 and record its position B; roughly locate the wafer coordinates through position A / B; Figure 1 Die 3 and Die 4 in the process respectively search for the above marks and record positions C and D; through position C / D, the wafer coordinates are accurately located.

[0006] In the existing wafer positioning method, the camera field of view used by the machine is small. When the accuracy of the pre-aligner on the machine is insufficient, the initial placement position of the wafer will have a large deviation. Figure 1 The search efficiency of marks in Die 1 and Die 2 is low. Summary of the invention

[0007] In view of some or all of the problems in the prior art, the present invention provides a wafer alignment method, which comprises the following steps:

[0008] Selecting a suitable alignment mark in the chip of the wafer to establish a work menu, and recording the position of the alignment mark and the size of the chip, wherein the alignment mark is a pattern with a significant shape difference from the surroundings and has a significant boundary;

[0009] Performing pre-alignment on the wafer using a pre-aligner, placing the wafer on a chuck, and recording a target angle of the wafer, the target angle being the angle at which the wafer is placed on the chuck;

[0010] Executing rough alignment of the wafer, including: determining the positions of two alignment marks closest to the center point of the wafer when the wafer is ideally placed and recording them as the best first position and the best second position; determining the positions of two alignment marks closest to the best first position and the best second position when the wafer is actually placed and recording them as the real first position and the real second position; determining the actual center point of the wafer and recording it as the real first center, determining the actual wafer angle and recording it as the real first angle; calculating the difference between the real first angle and the target angle and recording it as the first angle correction; if the first angle correction is greater than a first set threshold, performing a rotation operation of the first angle correction on the chuck, determining the actual center point of the wafer after rotation and recording it as the real second center; if the first angle correction is less than the first set threshold, completing the rough alignment of the wafer;

[0011] Executing fine alignment of a wafer, including: determining the positions of two alignment marks farthest from a wafer center point in a first direction and a second direction when the wafer is ideally placed and recording them as an ideal first direction position and an ideal second direction position; performing correction on the ideal first direction position and the ideal second direction position to obtain a corrected first direction position and a corrected second direction position; determining the positions of two alignment marks closest to the corrected first direction position and the corrected second direction position when the wafer is actually placed and recording them as a real first direction position and a real second direction position; determining the actual wafer center point and recording it as a real third center, determining the actual wafer angle and recording it as a real second angle; calculating the difference between the real second angle and the target angle and recording it as a second angle correction; if the second angle correction is greater than the second set threshold, performing a rotation operation on the chuck for the second angle correction; if the second angle correction is less than the second set threshold or the number of times the fine alignment of the wafer is performed reaches a set upper limit, the fine alignment of the wafer is completed.

[0012] Further, determining the positions of two alignment marks closest to the best first position and the best second position when the wafer is actually placed and recording them as the real first position and the real second position includes:

[0013] Move the chuck so that the center of the camera is aligned with the best first position to identify and match the alignment mark. If the alignment mark is not found, search around to determine the position of the alignment mark closest to the best first position and record it as the real first position;

[0014] The chuck is moved so that the center of the camera is aligned with the optimal second position to identify and match the alignment mark. If the alignment mark is not found, a search is performed around to determine the position of the alignment mark closest to the optimal second position and record it as the true second position.

[0015] Further, according to the optimal first position, the optimal second position, the real first position and the real second position, the actual wafer center point is determined and recorded as the real first center, and the actual wafer angle is determined and recorded as the real first angle;

[0016] The real first angle It is expressed by the following formula:

[0017]

[0018] in, , ,

[0019] in, is the x-coordinate of the actual first position, is the x-coordinate of the real second position, is the y coordinate of the real first position, is the y coordinate of the real second position, is the x-coordinate of the optimal first position, is the x-coordinate of the optimal second position, is the y coordinate of the optimal first position, The y coordinate of the optimal second position;

[0020] set up ,

[0021] Will Rotate the real first angle to obtain the vector for,

[0022]

[0023]

[0024] The True First Center for,

[0025]

[0026] in, .

[0027] Further, if the first angle correction is greater than the first set threshold, performing the first angle correction operation on the chuck includes:

[0028] If the first angle correction is a positive value, performing a reverse rotation on the chuck; and / or

[0029] If the first angle correction is a negative value, the chuck is rotated in a positive direction.

[0030] Further, the ideal first direction position and the ideal second direction position are corrected according to the real second center and the first angle correction to obtain a corrected first direction position and a corrected second direction position;

[0031] The first direction position is corrected It is expressed by the following formula:

[0032]

[0033] The second direction position is corrected It is expressed by the following formula:

[0034]

[0035] in, is the ideal first direction position, is the ideal second direction position, is said real second center;

[0036] It is expressed by the following formula:

[0037]

[0038]

[0039] in, , This is the first angle correction.

[0040] Further, according to the corrected first direction position, the corrected second direction position, the real first direction position and the real second direction position, the actual wafer center point is determined and recorded as the real third center, and the actual wafer angle is determined and recorded as the real second angle;

[0041] The real second angle It is expressed by the following formula:

[0042]

[0043] in, , ,

[0044] in, is the x-coordinate of the actual first direction position, is the x-coordinate of the real second direction position, is the y coordinate of the actual first direction position, is the y coordinate of the real second direction position, is the x-coordinate of the corrected first direction position, is the x-coordinate of the corrected second direction position, is the y coordinate of the corrected first direction position, The y coordinate of the second direction position of the correction;

[0045] set up ,

[0046] Will Rotate the real second angle to obtain the vector for,

[0047]

[0048]

[0049] The True Third Center for,

[0050]

[0051] in, .

[0052] Further, the first direction and the second direction are two of the following directions: a positive transverse direction, a negative transverse direction, a positive longitudinal direction, and a negative longitudinal direction.

[0053] Furthermore, the first set threshold is 0.01 degrees; and / or

[0054] The second set threshold is 0.01 degrees; and / or

[0055] The upper limit of the setting is 5 times.

[0056] The present invention also provides a wafer alignment device for use in the wafer alignment method, comprising:

[0057] Computers, configured to compute and store data;

[0058] a chuck configured to move or rotate the wafer;

[0059] a camera configured to identify matching alignment marks;

[0060] The pre-aligner is configured to perform pre-alignment on the wafer.

[0061] The present invention also provides a computer system, comprising:

[0062] a processor configured to execute machine-readable instructions;

[0063] a graphics card configured to train the wafer alignment method; and

[0064] The memory is configured to store machine-readable instructions, which, when executed by a processor and / or a graphics card, perform the steps of the wafer alignment method.

[0065] Compared with the prior art, the present invention has the following advantages:

[0066] 1. The wafer alignment method and related devices provided by the present invention improve the efficiency of searching for alignment marks in the subsequent precise alignment step by roughly aligning the wafer.

[0067] 2. The wafer alignment method and related device provided by the present invention can reduce the requirements for the accuracy of the pre-aligner by performing rough alignment near the center of the wafer, that is, when using a pre-aligner with slightly poor performance, rough alignment can also be quickly achieved.

[0068] 3. The wafer alignment method and related devices provided by the present invention perform precise alignment through alignment marks at the far end of the wafer, thereby improving the alignment accuracy of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] To further illustrate the above and other advantages and features of various embodiments of the present invention, a more specific description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings only depict typical embodiments of the present invention and are therefore not to be considered as limiting the scope thereof. In the accompanying drawings, for clarity, identical or corresponding parts will be represented by identical or similar reference numerals.

[0070] Figure 1 A schematic diagram of an existing wafer positioning method is shown;

[0071] Figure 2 A schematic diagram showing a process flow of a wafer alignment method according to an embodiment of the present invention is shown;

[0072] Figure 3 A schematic diagram showing the position of alignment marks on a wafer according to an embodiment of the present invention; and

[0073] Figure 4 A schematic diagram showing the actual placement of a wafer on a chuck according to an embodiment of the present invention. DETAILED DESCRIPTION

[0074] In the following description, the present invention is described with reference to various embodiments. However, those skilled in the art will recognize that various embodiments may be implemented without one or more specific details or with other replacement and / or additional methods or components. In other cases, well-known structures or operations are not shown or described in detail to avoid obscuring the inventive point of the present invention. Similarly, for the purpose of explanation, specific numbers and configurations are set forth to provide a comprehensive understanding of embodiments of the present invention. However, the present invention is not limited to these specific details.

[0075] In this specification, reference to "one embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. The phrase "in one embodiment" appearing in various places in this specification does not necessarily all refer to the same embodiment.

[0076] It should be noted that the embodiments of the present invention describe the method steps in a specific order, but this is only for the purpose of illustrating the specific embodiment, rather than limiting the order of the steps. On the contrary, in different embodiments of the present invention, the order of the steps can be adjusted according to actual needs.

[0077] The technical solutions in the embodiments of the present invention are described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0078] Figure 2 FIG. 1 is a schematic diagram showing a process flow of a wafer alignment method according to an embodiment of the present invention. Figure 2 As shown, the wafer alignment method includes the following steps:

[0079] First, select a suitable alignment mark in the chip (Die) of the wafer to establish a working menu, and record the position of the alignment mark and the size of the chip. The alignment mark (mark) is a pattern that has a significant shape difference from the surrounding area, and the alignment mark has a distinct boundary. In one embodiment of the present invention, there are multiple types of alignment marks, and different wafers may select different patterns as alignment marks. In one embodiment of the present invention, multiple alignment marks can be recorded at the same time. The more alignment marks there are, the higher the efficiency of searching for the alignment marks, but the higher the storage cost.

[0080] Next, use the pre-aligner to pre-align the wafer, place the wafer on the chuck, and record the target angle of the wafer. The target angle refers to the angle at which the wafer is placed on the chuck, because subsequent measurements of the wafer can only be performed at a specific angle. There are fixed notches or cutting marks on the wafer, such as Figure 1 As shown, the black dot in the middle below is the notch. The target angle generally refers to the notch direction. The production of wafers has specific rules. The distribution of chips in the wafer is generally distributed in the lateral direction or longitudinal direction downward from the wafer notch. The lateral direction is the horizontal direction, and the longitudinal direction is the vertical direction. The position of each alignment mark in each chip is fixed, so the wafer notch direction can be calculated by the alignment mark coordinates in the two chips in the horizontal or vertical direction.

[0081] Next, perform a rough alignment of the wafer. The rough alignment of the wafer includes the following steps:

[0082] According to the position of the alignment mark in the working menu and the size of the chip, a first position set of alignment marks in multiple chips located near the coordinate origin is determined, and the first position set includes multiple first positions, each of which is the position of the alignment mark relative to the coordinate origin. The coordinate origin is the ideal center point of the wafer. When establishing a working menu, three points that identify the edge of the wafer are recorded to calculate the ideal center point of the wafer. The first position set is a position set when the actual center point of the wafer coincides with the coordinate origin. The position of the alignment mark can include multiple positions, such as Figure 3 The coordinate axes are as shown in the A1 / A2 / A3 / A4 positions. Figure 4As shown, the center point of the ideal wafer placement position is the coordinate origin, the right side in the horizontal direction is the positive direction of the x-axis, and the upper side in the vertical direction is the positive direction of the y-axis.

[0083] A first position corresponding to an alignment mark closest to the coordinate origin in the first position set is determined and recorded as an optimal first position.

[0084] The chuck is moved so that the center of the camera is aligned with the optimal first position to identify and match the alignment mark. If the alignment mark is not found, a search is performed around to determine the position of the alignment mark closest to the optimal first position and record it as the true first position. The position of the camera is fixed, located above the origin of the chuck coordinates, and the camera field of view is small, and only a small local image on the wafer can be seen. By moving the chuck, the specified area on the wafer is displayed in the camera field of view. In one embodiment of the present invention, the camera identifies and matches the alignment mark, and the position of the alignment mark in the field of view can be found by the GMF algorithm. The size of the surrounding range is determined according to the maximum distance that the alignment mark may exceed the camera field of view due to the maximum error of the pre-aligner.

[0085] The difference between the real first position and the optimal first position is calculated and recorded as the real zeroth center. The coordinates of the real zeroth center are the coordinates of the real first position minus the coordinates of the optimal first position.

[0086] The position of the alignment mark closest to the true zeroth center is determined and recorded as the best second position.

[0087] The chuck is moved so that the center of the camera is aligned with the optimal second position to identify and match the alignment mark. If the alignment mark is not found, the alignment mark is searched around to determine the position of the alignment mark closest to the optimal second position and record it as the real second position. In one embodiment of the present invention, the camera identifies and matches the alignment mark, and the position of the alignment mark in the field of view can be found by the GMF algorithm. The size of the surrounding range is determined according to the maximum distance that the alignment mark may exceed the camera field of view due to the maximum error of the pre-aligner.

[0088] According to the optimal first position, the optimal second position, the real first position and the real second position, the actual wafer center point is determined and recorded as the real first center, and the actual wafer angle is determined and recorded as the real first angle.

[0089] like Figure 4As shown, the right side in the horizontal direction is the positive direction of the x-axis, and the upper side in the vertical direction is the positive direction of the y-axis. The center point of the ideal placement position of the wafer is the coordinate origin, and the optimal first position and the optimal second position are the positions of the alignment marks in the ideal placement position of the wafer. The actual placement position of the wafer deviates from the ideal placement position of the wafer, and the real first position and the real second position are the positions of the alignment marks in the actual placement position of the wafer.

[0090] The real first angle It is expressed by the following formula:

[0091]

[0092] in, ,

[0093] ,

[0094] in, is the x-coordinate of the actual first position, is the x-coordinate of the real second position, is the y coordinate of the real first position, is the y coordinate of the real second position, is the x-coordinate of the optimal first position, is the x-coordinate of the optimal second position, is the y coordinate of the optimal first position, The y coordinate of the optimal second position;

[0095] set up ,

[0096] Will Rotate the real first angle to obtain the vector for,

[0097]

[0098]

[0099] The True First Center for,

[0100]

[0101] in, .

[0102] The difference between the real first angle and the target angle is calculated and recorded as the first angle correction. The first angle correction AngleOffset1 is, AngleOffset1=RealAngle1-TargetAngle.

[0103] If the first angle correction is less than a first set threshold, the rough alignment of the wafer is completed. In one embodiment of the present invention, the first set threshold is 0.01 degrees.

[0104] If the first angle correction is greater than the first set threshold, the chuck is rotated by the first angle correction, and after the rotation, the first angle correction is assigned to 0, and the actual wafer center point is determined and recorded as the real second center. In one embodiment of the present invention, if the first angle correction is a positive value, the chuck is rotated in the reverse direction; and / or if the first angle correction is a negative value, the chuck is rotated in the forward direction.

[0105] Finally, fine alignment of the wafer is performed. Fine alignment of the wafer includes the following steps:

[0106] According to the position of the alignment mark in the working menu and the size of the chip, the position of the alignment mark in the chip farthest from the coordinate origin in the first direction is determined and recorded as the ideal first direction position.

[0107] The ideal first direction position is corrected according to the real second center and the first angle correction to obtain a corrected first direction position.

[0108] The first direction position is corrected It is expressed by the following formula:

[0109]

[0110] in, is the ideal first direction position, is said real second center;

[0111] It is expressed by the following formula:

[0112]

[0113]

[0114] in, , This is the first angle correction.

[0115] According to the position of the alignment mark in the working menu and the size of the chip, the position of the alignment mark in the chip farthest from the coordinate origin in the second direction is determined and recorded as the ideal second direction position. In one embodiment of the present invention, the first direction and the second direction are two of the following directions: a positive lateral direction, a negative lateral direction, a positive longitudinal direction, and a negative longitudinal direction. Figure 3As shown, the farthest distance from the coordinate origin in the positive horizontal direction, i.e. Xmax, is position E in the figure, the farthest distance from the coordinate origin in the negative horizontal direction, i.e. Xmin, is position D in the figure, the farthest distance from the coordinate origin in the positive longitudinal direction, i.e. Ymax, is position B in the figure, and the farthest distance from the coordinate origin in the negative longitudinal direction, i.e. Ymin, is position C in the figure.

[0116] The ideal second direction position is corrected according to the real second center and the first angle correction to obtain a corrected second direction position.

[0117] The second direction position is corrected It is expressed by the following formula:

[0118]

[0119] in, is the ideal second direction position, is said real second center;

[0120] It is expressed by the following formula:

[0121]

[0122]

[0123] in, , This is the first angle correction.

[0124] The chuck is moved so that the center of the camera is aligned with the corrected first direction position to identify and match the alignment mark. If the alignment mark is not found, the alignment mark is searched around to determine the position of the alignment mark closest to the corrected first direction position and recorded as the true first direction position. In one embodiment of the present invention, the camera identifies and matches the alignment mark, and the position of the alignment mark in the field of view can be found by the GMF algorithm. The size of the surrounding range is determined according to the maximum distance that the alignment mark may exceed the camera field of view due to the maximum error of the pre-aligner.

[0125] The chuck is moved so that the center of the camera is aligned with the corrected second direction position to identify and match the alignment mark. If the alignment mark is not found, the alignment mark is searched around to determine the position of the alignment mark closest to the corrected second direction position and recorded as the true second direction position. In one embodiment of the present invention, the camera identifies and matches the alignment mark, and the position of the alignment mark in the field of view can be found by the GMF algorithm. The size of the surrounding range is determined according to the maximum distance that the alignment mark may exceed the camera field of view due to the maximum error of the pre-aligner.

[0126] According to the corrected first direction position, the corrected second direction position, the real first direction position and the real second direction position, the actual wafer center point is determined and recorded as the real third center, and the actual wafer angle is determined and recorded as the real second angle.

[0127] The real second angle It is expressed by the following formula:

[0128]

[0129] in, ,

[0130] ,

[0131] in, is the x-coordinate of the actual first direction position, is the x-coordinate of the real second direction position, is the y coordinate of the actual first direction position, is the y coordinate of the real second direction position, is the x-coordinate of the corrected first direction position, is the x-coordinate of the corrected second direction position, is the y coordinate of the corrected first direction position, The y coordinate of the second direction position of the correction;

[0132] set up ,

[0133] Will Rotate the real second angle to obtain the vector for,

[0134]

[0135]

[0136] The True Third Center for,

[0137]

[0138] in, .

[0139] The difference between the real second angle and the target angle is calculated and recorded as the second angle correction. The second angle correction AngleOffset2 is, AngleOffset2=RealAngle2-TargetAngle.

[0140] If the second angle correction is less than a second set threshold, the fine alignment of the wafer is completed. In one embodiment of the present invention, the second set threshold is 0.01 degrees.

[0141] If the second angle correction is greater than the second set threshold, the chuck is rotated by the second angle correction, and after the rotation, the second angle correction is assigned a value of 0, and the fine alignment of the wafer is repeated.

[0142] If the number of times the wafer fine alignment is performed reaches a set upper limit, the wafer fine alignment is stopped. In one embodiment of the present invention, the set upper limit is 5 times. Generally, repeating the wafer fine alignment twice can meet the requirement that the second angle correction is less than the second set threshold.

[0143] The wafer alignment method provided by the present invention improves the efficiency of searching for alignment marks in a subsequent precise alignment step by roughly aligning the wafer; reduces the requirements on the accuracy of the pre-aligner by performing rough alignment near the center of the wafer; and improves the alignment accuracy of the wafer by performing precise alignment through the alignment marks at the far end of the wafer.

[0144] In one embodiment of the present invention, the present invention also provides a wafer alignment device, which is used to implement the wafer alignment method. The wafer alignment device includes: a computer, configured to calculate and store data generated in the wafer alignment method; a chuck, configured to move or rotate the wafer so that the camera center is aligned with the alignment mark that needs to be identified and matched; a camera, configured to identify the matching alignment mark; and a pre-aligner, configured to perform pre-alignment on the wafer.

[0145] In one embodiment of the present invention, the present invention also provides a computer system, which includes a processor, a graphics card and a memory, wherein the memory is configured to store machine-readable instructions, the graphics card is configured to train the wafer alignment method, and the processor is configured to execute the machine-readable instructions. When the processor and / or the graphics card execute the machine-readable instructions, the following processing steps are implemented: selecting a suitable alignment mark in the chip of the wafer to establish a work menu, and recording the position of the alignment mark and the size of the chip; performing pre-alignment on the wafer using a pre-aligner, placing the wafer on a chuck, and recording the target angle of the wafer; performing rough alignment of the wafer; and performing fine alignment of the wafer.

[0146] The graphics card may preferably have a GPU computing power higher than 5.0. Since the amount of data to be trained is large, providing a graphics card configuration can significantly increase the training speed.

[0147] The memory includes: a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk, and other media that can store machine-readable instructions.

[0148] It can be understood that in addition to the memory and processor mentioned above, the above-mentioned computer system also includes other software and hardware components not listed in this specification. The specific components can be determined according to the model of specific data processing equipment in different application scenarios, and this specification will not list them one by one in detail.

[0149] Although various embodiments of the present invention are described above, it should be understood that they are presented as examples only and not as limitations. It is obvious to those skilled in the relevant art that various combinations, modifications and changes can be made thereto without departing from the spirit and scope of the present invention. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should only be defined according to the technical solutions of the present invention and their equivalents.

Claims

1. A wafer alignment method, characterized in that: The steps include: Selecting a suitable alignment mark in the chip of the wafer to establish a work menu, and recording the position of the alignment mark and the size of the chip, wherein the alignment mark is a pattern with a significant shape difference from the surroundings and has a significant boundary; Performing pre-alignment on the wafer using a pre-aligner, placing the wafer on a chuck, and recording a target angle of the wafer, the target angle being the angle at which the wafer is placed on the chuck; Executing rough alignment of the wafer, including: determining the positions of two alignment marks closest to the center point of the wafer when the wafer is ideally placed and recording them as the best first position and the best second position; determining the positions of two alignment marks closest to the best first position and the best second position when the wafer is actually placed and recording them as the real first position and the real second position; determining the actual center point of the wafer and recording it as the real first center, determining the actual wafer angle and recording it as the real first angle; calculating the difference between the real first angle and the target angle and recording it as the first angle correction; if the first angle correction is greater than a first set threshold, performing a rotation operation of the first angle correction on the chuck, determining the actual center point of the wafer after rotation and recording it as the real second center; if the first angle correction is less than the first set threshold, completing the rough alignment of the wafer; Executing fine alignment of a wafer, including: determining the positions of two alignment marks farthest from a wafer center point in a first direction and a second direction when the wafer is ideally placed and recording them as an ideal first direction position and an ideal second direction position; performing correction on the ideal first direction position and the ideal second direction position to obtain a corrected first direction position and a corrected second direction position; determining the positions of two alignment marks closest to the corrected first direction position and the corrected second direction position when the wafer is actually placed and recording them as a real first direction position and a real second direction position; determining the actual wafer center point and recording it as a real third center, determining the actual wafer angle and recording it as a real second angle; calculating the difference between the real second angle and the target angle and recording it as a second angle correction; if the second angle correction is greater than a second set threshold, performing a rotation operation of the second angle correction on the chuck; if the second angle correction is less than a second set threshold or the number of times the fine alignment of the wafer is performed reaches a set upper limit, the fine alignment of the wafer is completed.

2. The wafer alignment method according to claim 1, characterized in that: Determining the positions of two alignment marks closest to the best first position and the best second position when the wafer is actually placed and recording them as the real first position and the real second position includes: Move the chuck so that the center of the camera is aligned with the best first position to identify and match the alignment mark. If the alignment mark is not found, search around to determine the position of the alignment mark closest to the best first position and record it as the real first position; The chuck is moved so that the center of the camera is aligned with the optimal second position to identify and match the alignment mark. If the alignment mark is not found, a search is performed around to determine the position of the alignment mark closest to the optimal second position and record it as the true second position.

3. The wafer alignment method according to claim 1, characterized in that: According to the optimal first position, the optimal second position, the real first position and the real second position, determining the actual wafer center point and recording it as the real first center, determining the actual wafer angle and recording it as the real first angle; The real first angle It is expressed by the following formula: ， in, , , in, is the x-coordinate of the actual first position, is the x-coordinate of the real second position, is the y coordinate of the real first position, is the y coordinate of the real second position, is the x-coordinate of the optimal first position, is the x-coordinate of the optimal second position, is the y coordinate of the optimal first position, The y coordinate of the optimal second position; set up , Will Rotate the real first angle to obtain the vector for, ， ， The True First Center for, ， in, .

4. The wafer alignment method according to claim 1, characterized in that: If the first angle correction is greater than the first set threshold, performing the first angle correction operation on the chuck includes: If the first angle correction is a positive value, performing a reverse rotation on the chuck; and / or If the first angle correction is a negative value, the chuck is rotated in a positive direction.

5. The wafer alignment method according to claim 1, characterized in that: Correcting the ideal first direction position and the ideal second direction position according to the real second center and the first angle correction to obtain a corrected first direction position and a corrected second direction position; The first direction position is corrected It is expressed by the following formula: ， The second direction position is corrected It is expressed by the following formula: ， in, is the ideal first direction position, is the ideal second direction position, is said real second center; It is expressed by the following formula: ， ， in, , This is the first angle correction.

6. The wafer alignment method according to claim 1, characterized in that: According to the corrected first direction position, the corrected second direction position, the real first direction position and the real second direction position, the actual wafer center point is determined and recorded as the real third center, and the actual wafer angle is determined and recorded as the real second angle; The real second angle It is expressed by the following formula: ， in, , , in, is the x-coordinate of the actual first direction position, is the x-coordinate of the real second direction position, is the y coordinate of the actual first direction position, is the y coordinate of the real second direction position, is the x-coordinate of the corrected first direction position, is the x-coordinate of the corrected second direction position, is the y coordinate of the corrected first direction position, The y coordinate of the second direction position of the correction; set up , Will Rotate the real second angle to obtain the vector for, ， ， The True Third Center for, ， in, .

7. The wafer alignment method according to claim 1, characterized in that: The first direction and the second direction are two of the following directions: a positive transverse direction, a negative transverse direction, a positive longitudinal direction, and a negative longitudinal direction.

8. The wafer alignment method according to claim 1, characterized in that: The first set threshold is 0.01 degrees; and / or The second set threshold is 0.01 degrees; and / or The upper limit of the setting is 5 times.

9. A wafer alignment device used in the wafer alignment method according to any one of claims 1 to 8, characterized in that: include: Computers, configured to compute and store data; a chuck configured to move or rotate the wafer; a camera configured to identify matching alignment marks; The pre-aligner is configured to perform pre-alignment on the wafer.

10. A computer system, characterized in that: include: a processor configured to execute machine-readable instructions; a graphics card configured to train the wafer alignment method; as well as A memory configured to store machine-readable instructions, wherein the machine-readable instructions, when executed by a processor and / or a graphics card, perform the steps of the wafer alignment method according to any one of claims 1 to 8.

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