Wafer position pre-alignment method, electronic device and wafer transfer system

Abstract

The application provides a wafer position pre-alignment method, an electronic device and a wafer transmission system. The method comprises the following steps: obtaining a first target image of a first mark of a wafer to be aligned, and determining a current position of the first mark; determining an expected current position of a second mark based on the current position of the first mark and a position relationship between the first mark and the second mark; controlling a wafer carrying platform to move based on the expected current position of the second mark, obtaining a second target image of the second mark of the wafer to be aligned, and determining a current position of the second mark; determining a centroid position of the wafer to be aligned and a wafer centroid offset based on the current position of the first mark and the current position of the second mark; and controlling the wafer carrying platform to move according to the wafer centroid offset, and moving the centroid position of the wafer to be aligned to a target position. By using the wafer position pre-alignment method, the electronic device and the wafer transmission system, the problem that the existing wafer position pre-alignment process is relatively complex is solved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically, to a wafer positioning pre-alignment method, electronic device, and wafer transport system. Background Technology

[0002] With the continuous development of semiconductor technology, the wafer processing process is becoming increasingly complex, and the requirements for wafer transfer accuracy during wafer processing are also becoming higher. Wafer transfer is accomplished through a wafer transfer system. Before the transfer is completed, the wafer needs to be pre-aligned so that its aligned position meets the accuracy requirements.

[0003] Currently, the wafer pre-alignment scheme involves placing the wafer on the pre-alignment stage of the wafer transport system and using line scan cameras and area scan cameras to position and align the wafer. This scheme not only requires setting up a pre-alignment stage with relatively complex mechanical and electrical mechanisms, but also requires using line scan cameras and area scan cameras to position and align the wafer, resulting in a complex wafer pre-alignment process and a large space occupied by the entire wafer transport system. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a wafer pre-alignment method, electronic device and wafer transfer system, which solves the problem of the relatively complex wafer pre-alignment process.

[0005] In a first aspect, embodiments of this application provide a wafer pre-alignment method applied to a wafer transport system. The wafer transport system includes a wafer carrier platform on which a wafer to be aligned is placed. The surface of the wafer to be aligned is provided with a first mark and a second mark. The method includes:

[0006] Acquire the first target image of the first mark on the wafer to be aligned, and determine the current position of the first mark;

[0007] Based on the current position of the first marker and the positional relationship between the first marker and the second marker, determine the expected current position of the second marker;

[0008] Based on the expected current position of the second mark, the wafer carrier platform is moved to acquire a second target image of the second mark on the wafer to be aligned, and the current position of the second mark is determined.

[0009] Based on the current position of the first mark and the current position of the second mark, the centroid position of the wafer to be aligned and the wafer centroid offset are determined by utilizing the positional relationship between the first mark, the second mark, and the centroid position of the wafer to be aligned. The wafer centroid offset is the offset between the centroid position of the wafer to be aligned and the target position.

[0010] The wafer carrier platform is moved according to the wafer center offset to move the centroid of the wafer to be aligned to the target position.

[0011] Optionally, the wafer transfer system further includes a camera device; acquiring a first target image of the first mark on the wafer to be aligned and determining the current position of the first mark, including: acquiring the size information of the wafer to be aligned; determining the reference position of the first mark on the wafer to be aligned based on the size information of the wafer to be aligned; determining the offset of the reference position of the first mark on the wafer to be aligned relative to the position of the camera device; controlling the wafer carrier platform to move based on the offset of the reference position of the first mark relative to the position of the camera device, so that the reference position of the first mark on the wafer to be aligned is within the field of view of the camera device; controlling the camera device to take a picture of the first mark on the wafer to be aligned to acquire a first target image; and using an image recognition algorithm to analyze the first target image to determine the current position of the first mark.

[0012] Optionally, controlling the wafer carrier platform to move based on the expected current position of the second mark, acquiring a second target image of the second mark on the wafer to be aligned, and determining the current position of the second mark includes: determining the offset between the expected current position of the second mark and the position of the camera device based on the expected current position of the second mark; controlling the wafer carrier platform to move according to the offset between the expected current position of the second mark and the position of the camera device, so that the expected current position of the second mark on the wafer to be aligned is within the field of view of the camera device; controlling the camera device to take a picture of the second mark on the wafer to be aligned to acquire a second target image; and using an image recognition algorithm to analyze the second target image to determine the current position of the second mark.

[0013] Optionally, based on the current position of the first marker and the current position of the second marker, the centroid position of the wafer to be aligned and the wafer centroid offset are determined using the positional relationship between the first marker, the second marker, and the centroid position of the wafer to be aligned, including: obtaining the target position of the wafer centroid; based on the current position of the first marker and the current position of the second marker, the centroid position of the wafer to be aligned is determined using the positional relationship between the first marker, the second marker, and the centroid position of the wafer to be aligned; and based on the centroid position of the wafer to be aligned and the target position, the wafer centroid offset is determined.

[0014] Optionally, the wafer center offset includes an angular offset and a distance offset, and the wafer carrier platform includes a rotating platform; controlling the wafer carrier platform to move according to the wafer center offset to move the centroid position of the wafer to be aligned to the target position includes: controlling the rotating platform on the wafer carrier platform to rotate according to the angular offset to eliminate the angular offset; and controlling the wafer carrier platform to move according to the distance offset to eliminate the distance offset and move the centroid position of the wafer to be aligned to the target position.

[0015] Optionally, after controlling the movement of the wafer carrier platform according to the wafer center offset to move the centroid position of the wafer to be aligned to the target position, the method further includes: re-determining the current position of the second mark of the wafer to be aligned; obtaining the second mark offset between the re-determined current position of the second mark of the wafer to be aligned and the reference position of the second mark; and using the second mark offset to determine whether the pre-alignment of the wafer to be aligned is completed.

[0016] Optionally, the current position of the second mark on the wafer to be aligned is determined again, including: acquiring a third target image of the second mark on the wafer to be aligned; and using an image recognition algorithm to analyze the third target image to determine the current position of the second mark on the wafer to be aligned again.

[0017] Optionally, the pre-alignment of the wafer to be aligned is determined using the second mark offset, including: determining whether the second mark offset is less than an offset threshold; if it is less than the offset threshold, the pre-alignment of the wafer to be aligned is completed; if it is not less than the offset threshold, the process returns to the step of obtaining the first target image of the first mark of the wafer to be aligned and determining the current position of the first mark.

[0018] Secondly, embodiments of this application also provide a wafer transport system, the system comprising:

[0019] Control unit, wafer carrier platform, camera equipment;

[0020] The control unit performs steps such as wafer position pre-alignment methods;

[0021] The control unit is connected to the wafer carrier platform to control the movement of the wafer carrier platform;

[0022] The control unit is connected to the camera device to control the camera device to take pictures of the first mark and the second mark on the wafer to be aligned;

[0023] The camera equipment is located above the wafer carrier platform.

[0024] Thirdly, embodiments of this application also provide an electronic device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, the steps of the wafer position pre-alignment method described above are performed.

[0025] The embodiments of this application bring the following beneficial effects:

[0026] This application provides a wafer pre-alignment method, electronic device, and wafer transfer system. It can determine the current position of a first marker through a first target image, determine the current position of a second marker through the current position of the first marker and the positional relationship between the first and second markers, determine the wafer center offset based on the current positions of the first and second markers, and control the wafer carrier platform to move so that the centroid of the wafer to be aligned moves to the target position. Wafer pre-alignment can be completed solely through the wafer carrier platform, eliminating the need for a pre-alignment platform. Compared with existing wafer pre-alignment methods, this solves the problem of a complex wafer pre-alignment process.

[0027] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A flowchart of the wafer position pre-alignment method provided in an embodiment of this application is shown;

[0030] Figure 2 A schematic diagram of the wafer carrier platform provided in an embodiment of this application is shown;

[0031] Figure 3 A schematic diagram of the first and second markings provided in an embodiment of this application is shown;

[0032] Figure 4 A schematic diagram of the wafer transmission system provided in an embodiment of this application is shown;

[0033] Figure 5 A schematic diagram of the control unit provided in an embodiment of this application is shown;

[0034] Figure 6 A schematic diagram of the structure of the electronic device provided in the embodiments of this application is shown. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.

[0036] It is worth noting that prior to this application, with the continuous development of semiconductor technology, the wafer fabrication process has become increasingly complex, and the requirements for wafer transfer accuracy during wafer fabrication have become increasingly stringent. Wafer transfer is accomplished through a wafer transfer system. Before transfer, the wafer needs to be pre-aligned to ensure that its position meets the accuracy requirements. Currently, the wafer pre-alignment scheme involves placing the wafer on the pre-alignment stage of the wafer transfer system and using line scan and area scan cameras to position and align the wafer. This scheme not only requires a pre-alignment stage with relatively complex mechanical and electrical mechanisms but also requires the use of line scan and area scan cameras for wafer positioning and alignment, resulting in a complex wafer pre-alignment process and a large space requirement for the entire wafer transfer system.

[0037] Based on this, embodiments of this application provide a wafer position pre-alignment method to simplify the pre-alignment process and reduce the space occupied by the wafer transport system.

[0038] Please see Figure 1 , Figure 1 This is a flowchart illustrating a wafer positioning pre-alignment method provided in an embodiment of this application. Figure 1 As shown in the embodiments of this application, the wafer positioning pre-alignment method is applied to a wafer transport system. The wafer transport system includes a wafer carrier platform, on which a wafer to be aligned is placed. A first mark and a second mark are provided on the surface of the wafer to be aligned. The method includes:

[0039] Step S101: Obtain the first target image of the first mark on the wafer to be aligned, and determine the current position of the first mark.

[0040] In this step, the first target image can refer to the image obtained by taking a picture of the first mark on the wafer to be aligned. The first target image is used to determine the position of the first mark.

[0041] A wafer carrier platform refers to a platform on which a wafer to be aligned is placed. A wafer carrier platform is square.

[0042] The following reference Figure 2 Let's introduce the wafer carrier platform.

[0043] Figure 2 A schematic diagram of the structure of the wafer carrier platform provided in an embodiment of this application is shown.

[0044] like Figure 2 As shown, the wafer carrier platform 201 includes a rotating platform 202, which rotates around a rotation center 203. The rotating platform 202 has multiple wafer slots of different types, including a first wafer slot 204, a second wafer slot 205, and a third wafer slot 206.

[0045] A wafer bay refers to a bay where wafers are placed. Wafer bays are used to determine the approximate placement of different types of wafers.

[0046] The wafer to be aligned can refer to the wafer to be pre-aligned. The wafer to be aligned is placed in the corresponding wafer slot of the rotating platform of the wafer carrier platform according to the wafer type.

[0047] The wafer surface to be aligned has a first mark and a second mark.

[0048] The first mark and the second mark are marks with the same shape but different positions. For example, the shape of the first mark and the second mark can be a cross, a star, or a rectangle.

[0049] The following reference Figure 3 Let's introduce the first and second markers.

[0050] Figure 3 A schematic diagram of the first and second markings provided in the embodiments of this application is shown.

[0051] like Figure 3 As shown, the wafer surface of the wafer to be aligned 300 has a first mark 301 and a second mark 302. The first mark 301 and the second mark 302 are two marks with the same shape but different positions.

[0052] In this embodiment of the application, an image coordinate system and a measurement coordinate system are first constructed. The image coordinate system is a Cartesian coordinate system, with the plane captured by the camera as the coordinate plane. The origin of the image coordinate system is the upper left corner of the photosensitive unit of the camera. The unit of the horizontal and vertical coordinates of the image coordinate system is pixels.

[0053] The measurement coordinate system is a plane rectangular coordinate system, with the upper surface of the wafer carrier platform as the coordinate plane. The units of the abscissa and ordinate of the measurement coordinate system are millimeters. The origin of the measurement coordinate system is the center of rotation. The abscissa axis of the measurement coordinate system is parallel to the lateral movement direction of the wafer carrier platform, and the ordinate axis of the measurement coordinate system is parallel to the longitudinal movement direction of the wafer carrier platform.

[0054] Specifically, a camera device can be controlled to capture an image of the first mark on the wafer carrier platform to be aligned. Based on the captured image, the position of the first mark in the image coordinate system is determined. Then, according to the transformation relationship between the image coordinate system and the measurement coordinate system, the position of the first mark in the measurement coordinate system is determined, and this position is defined as the current position of the first mark. The transformation relationship between the image coordinate system and the measurement coordinate system is known and can be stored in a database.

[0055] In an optional embodiment, the wafer transfer system further includes a camera device; the execution step S101 includes: acquiring the size information of the wafer to be aligned; determining the reference position of the first mark of the wafer to be aligned based on the size information of the wafer to be aligned; determining the offset of the reference position of the first mark of the wafer to be aligned relative to the position of the camera device; controlling the wafer carrier platform to move based on the offset of the reference position of the first mark relative to the position of the camera device, so that the reference position of the first mark of the wafer to be aligned is within the field of view of the camera device; controlling the camera device to take a picture of the first mark of the wafer to be aligned to acquire a first target image; and using an image recognition algorithm to analyze the first target image to determine the current position of the first mark.

[0056] Here, the camera device can refer to a photographing device. The camera device is used to acquire a first target image and a second target image. For example, the camera device can be a Mark Sensor (area scan camera).

[0057] Size information can refer to the external dimensions of a wafer. For example, for a round wafer, the size information can refer to the radius of the wafer. For a square wafer, the size information can refer to the length and width of the wafer.

[0058] The reference position of the first mark can refer to the position of the first mark in the measurement coordinate system when no positional deviation occurs during the wafer transfer process.

[0059] Specifically, based on the size information of the wafer to be aligned, the wafer slot corresponding to the wafer to be aligned can be determined. Assuming that the wafer slot corresponding to the wafer to be aligned is the first wafer slot, the reference position of the first mark corresponding to the first wafer slot can be obtained from the database. Based on the reference position of the first mark and the position of the camera device, the offset of the reference position of the first mark of the wafer to be aligned relative to the position of the camera device can be determined. Based on this offset, the wafer carrier platform is controlled to move so that the camera device is aligned with the reference position of the first mark of the wafer to be aligned. Then, the camera device is controlled to take a picture of the first mark of the wafer to be aligned to obtain the first target image.

[0060] It should be noted that since the camera is aimed at the reference position of the first mark on the wafer to be aligned, and there may be a slight deviation between the reference position of the first mark and the current position of the first mark, the first mark may not be in the first target image. If this happens, the wafer transfer system will issue a position error prompt, indicating to the staff that the first mark is not in the field of view of the camera, and at the same time stop the pre-alignment process. After the above error is corrected, the wafer position pre-alignment can be performed again.

[0061] Step S102: Based on the current position of the first marker and the positional relationship between the first marker and the second marker, determine the expected current position of the second marker.

[0062] In this step, the positional relationship between the first and second markers can refer to the pre-determined distance between the center points of the first and second markers. This positional relationship is used to determine the expected current position of the second marker using the current position of the first marker. The positional relationship between the first and second markers can be stored in a database or obtained from externally received data.

[0063] In this embodiment of the application, taking a horizontal distance of 20 mm between the first mark and the second mark as an example, and the coordinates of the current position of the first mark as [10, 10], the expected coordinates of the current position of the second mark can be determined as [30, 10].

[0064] Step S103: Based on the expected current position of the second mark, control the wafer carrier platform to move, acquire a second target image of the second mark on the wafer to be aligned, and determine the current position of the second mark.

[0065] In this step, the second target image can refer to the image obtained by taking a picture of the second mark on the wafer to be aligned. The second target image is used to determine the position of the second mark.

[0066] In this embodiment, since the expected current position of the second mark is known, the wafer carrier platform can be moved so that the expected current position of the second mark is within the field of view of the camera device. The camera device can then be controlled to take a picture of the second mark to obtain a second target image. The position of the second mark in the image coordinate system can be obtained by analyzing the second target image. Then, by using the transformation relationship between the image coordinate system and the measurement coordinate system, the position of the second mark in the measurement coordinate system can be determined, and the position of the second mark in the measurement coordinate system can be determined as the current position of the second mark.

[0067] In an optional embodiment, step S103 includes: determining the offset between the expected current position of the second mark and the position of the camera device based on the expected current position of the second mark; controlling the wafer carrier platform to move according to the offset between the expected current position of the second mark and the position of the camera device, so that the expected current position of the second mark of the wafer to be aligned is within the field of view of the camera device; controlling the camera device to take a picture of the second mark of the wafer to be aligned to obtain a second target image; and using an image recognition algorithm to analyze the second target image to determine the current position of the second mark.

[0068] Here, since the expected current position of the second marker and the position of the camera device are known, the offset between the expected current position of the second marker and the position of the camera device can be determined. Taking the example above, the expected current position of the second marker is [30, 10], and the position of the camera device is [10.2, 10]. Therefore, the offset between the expected current position of the second marker and the position of the camera device is [19.8, 0]. After controlling the wafer carrier platform to move 19.8 mm horizontally along the measurement coordinate system, the expected current position of the second marker on the wafer to be aligned is placed within the field of view of the camera device. Then, the camera device is controlled to take a picture of the second marker on the wafer to be aligned to obtain a second target image. An image recognition algorithm is used to analyze the second target image to obtain the position of the second marker in the image coordinate system. Then, using the transformation relationship between the image coordinate system and the measurement coordinate system, the position of the second marker in the measurement coordinate system is determined, and this position is defined as the current position of the second marker. The image recognition algorithm is existing technology and will not be elaborated upon here.

[0069] It should be noted that since the expected current position of the second marker is determined based on the current position of the first marker, the current position of the second marker may deviate from the expected position due to angular tilt, resulting in the second marker not appearing in the second target image. If this occurs, the wafer transfer system will issue a position error prompt, indicating to the staff that the second marker is not in the field of view of the camera equipment, and at the same time stop the pre-alignment process. After the above error is corrected, the wafer position pre-alignment can be performed again.

[0070] Step S104: Based on the current position of the first mark and the current position of the second mark, the centroid position of the wafer to be aligned and the wafer centroid offset are determined by utilizing the positional relationship between the first mark, the second mark, and the centroid position of the wafer to be aligned.

[0071] In this step, the centroid of the wafer to be aligned can refer to the center point of the wafer. For example, the centroid of a circular wafer is the center of the wafer, and the centroid of a square wafer is the intersection of the two diagonals of the wafer.

[0072] The centroid position of the wafer to be aligned can refer to the current position of the center point of the wafer to be aligned.

[0073] The target position can refer to the centroid position of the wafer when there is no positional deviation during wafer transfer. The target position is used to compare with the current centroid position of the wafer to be aligned in order to determine the alignment distance and angle.

[0074] The wafer center offset is the offset between the centroid position of the wafer to be aligned and the target position. The wafer center offset includes angular offset and distance offset.

[0075] In this embodiment, the positional relationship between the first marker, the second marker, and the center of the wafer to be aligned is stored in a database in advance. Based on the positional relationship of the three, the current position of the first marker, and the current position of the second marker, the centroid position of the wafer to be aligned, the wafer center angle offset, and the wafer center distance offset can be calculated.

[0076] In an optional embodiment, step S104 includes: obtaining the target position of the center of the wafer to be aligned; determining the centroid position of the wafer to be aligned based on the current position of the first marker and the current position of the second marker, using the positional relationship between the first marker, the second marker, and the centroid position of the wafer to be aligned; and determining the wafer center offset based on the centroid position of the wafer to be aligned and the target position.

[0077] Here, the target position is stored in the database. First, the target position and target angle of the wafer center to be aligned can be obtained from the database. Then, based on the current position of the first marker, the current position of the second marker, and the positional relationship between the first marker, the second marker, and the centroid position of the wafer to be aligned, the centroid position of the wafer to be aligned is calculated. Then, based on the centroid position of the wafer to be aligned and the obtained target position, the wafer center distance offset is determined.

[0078] Simultaneously, the midpoint of the line connecting the current position of the first mark and the current position of the second mark is taken as the mark midpoint, the line connecting the mark midpoint and the centroid position of the wafer to be aligned is taken as the current axis of the wafer to be aligned, the angle between the current axis of the wafer to be aligned and the horizontal direction of the measurement coordinate system is taken as the current angle of the wafer to be aligned, and the difference between the current angle of the wafer to be aligned and the target angle is taken as the wafer centroid angle offset.

[0079] The target angle is determined as follows: the midpoint of the line connecting the reference position of the first mark and the reference position of the second mark is taken as the midpoint of the reference mark, the line connecting the midpoint of the reference mark and the target position is taken as the reference axis, and the angle between the reference axis and the horizontal direction of the measurement coordinate system is taken as the target angle.

[0080] Step S105: Control the movement of the wafer carrier platform according to the wafer center offset to move the centroid position of the wafer to be aligned to the target position.

[0081] In this embodiment of the application, the offset between the centroid position of the wafer to be aligned and the target position has been determined. The centroid position of the wafer to be aligned can be moved to the target position by controlling the wafer carrier platform.

[0082] In an optional embodiment, the wafer center offset includes an angular offset and a distance offset, and the wafer carrier platform includes a rotating platform; the execution step S105 includes: controlling the rotating platform on the wafer carrier platform to rotate according to the angular offset to eliminate the angular offset; controlling the wafer carrier platform to move according to the distance offset to eliminate the distance offset, and moving the centroid position of the wafer to be aligned to the target position.

[0083] Here, the angular offset refers to the angle between the current axis of the wafer to be aligned and the reference axis. The angular offset is used to calibrate the placement angle of the wafer to be aligned.

[0084] Distance offset refers to the offset distance between the centroid of the wafer to be aligned and the target position. Distance offset is used to calibrate the placement of the wafer to be aligned.

[0085] Specifically, the placement angle of the wafer to be aligned can be calibrated first by controlling the rotating platform to rotate according to the angular offset, and then the placement position of the wafer to be aligned can be calibrated by controlling the wafer carrier platform to move according to the distance offset. It should be noted that the sign of the angular offset determines whether the rotating platform rotates clockwise or counterclockwise.

[0086] In one optional embodiment, after controlling the movement of the wafer carrier platform according to the wafer center offset to move the centroid position of the wafer to be aligned to the target position, the method further includes: re-determining the current position of the second mark of the wafer to be aligned; obtaining the second mark offset between the re-determined current position of the second mark of the wafer to be aligned and the reference position of the second mark; and using the second mark offset to determine whether the pre-alignment of the wafer to be aligned is completed.

[0087] Here, the second mark offset can refer to the distance offset, which is the distance offset between the second mark after the first alignment and the reference position of the second mark.

[0088] Specifically, after moving the centroid of the wafer to be aligned to the target position, there may still be a certain offset between the centroid and the target position, requiring re-alignment of the wafer. At this point, a second marker can be used to determine whether the wafer has completed pre-alignment. The offset between the current position of the second marker after the first alignment and its reference position is used to determine whether the wafer's position meets the alignment accuracy requirements after the first alignment.

[0089] In one optional embodiment, determining the current position of the second mark on the wafer to be aligned again includes: acquiring a third target image of the second mark on the wafer to be aligned; and using an image recognition algorithm to analyze the third target image to determine the current position of the second mark on the wafer to be aligned again.

[0090] Here, the offset between the centroid of the wafer to be aligned and the target position before the first alignment is not large. Therefore, after the first alignment, the current position of the second mark is still within the field of view of the camera device. The second mark can be photographed again to obtain the third target image. Then, the image recognition algorithm is used to analyze the third target image to determine the current position of the second mark of the wafer to be aligned after the first alignment.

[0091] In one optional embodiment, determining whether the pre-alignment of the wafer to be aligned is completed using the second mark offset includes: determining whether the second mark offset is less than an offset threshold; if it is less than the offset threshold, then the pre-alignment of the wafer to be aligned is completed; if it is not less than the offset threshold, then returning to the step of using a camera device to acquire a first target image of the first mark of the wafer to be aligned on the wafer carrier platform and determining the current position of the first mark.

[0092] Here, the pre-alignment of the wafer to be aligned can be determined by comparing the second mark offset with an offset threshold. If it is less than the offset threshold, the alignment accuracy requirement is met, and the pre-alignment of the wafer to be aligned is complete. If it is not less than the offset threshold, the alignment accuracy requirement is not met, and the pre-alignment of the wafer to be aligned is not complete. In this case, it is necessary to return to step S101 to perform multiple pre-alignment processes on the wafer to be aligned until, after the Nth alignment, the second mark offset of the wafer to be aligned is less than the offset threshold, which means the alignment accuracy requirement is met.

[0093] It should be noted that, in order to avoid infinite loops or improve alignment efficiency, the maximum value of the alignment number N can be limited. For example, if the offset of the second mark on the wafer to be aligned is still not less than the offset threshold after the third alignment, the pre-alignment will stop and a pre-alignment failure message will be displayed.

[0094] Compared with existing wafer pre-alignment methods, this application can determine the current position of the first mark through the first target image, determine the current position of the second mark through the current position of the first mark and the positional relationship between the first mark and the second mark, determine the wafer center offset based on the current positions of the first mark and the second mark, and control the wafer carrier platform to move so that the centroid of the wafer to be aligned moves to the target position. Wafer pre-alignment can be completed using only the wafer carrier platform and a camera device, without having to move the wafer to be aligned from the wafer carrier platform to the pre-alignment platform and then perform pre-alignment through the pre-alignment platform which has a relatively complex mechanical and electrical structure. This reduces the complexity of the pre-alignment process and solves the problem of the complex wafer pre-alignment process. At the same time, it can also use the current position of the second mark to perform multiple pre-alignment processes on the wafer to be aligned, thereby improving the pre-alignment accuracy of the wafer position.

[0095] Based on the same inventive concept, this application also provides a wafer transfer system corresponding to the wafer position pre-alignment method. Since the principle of the system in this application is similar to the wafer position pre-alignment method described above in this application, the implementation of the system can refer to the implementation of the method, and the repeated parts will not be described again.

[0096] Please see Figure 4 , Figure 4 This is a schematic diagram of a wafer transmission system provided in an embodiment of this application. Figure 4 As shown, the wafer transport system 400 includes:

[0097] Control unit 410, wafer carrier platform 420, camera equipment 430;

[0098] The control unit 410 performs steps such as those in a wafer position pre-alignment method;

[0099] The control unit 410 is connected to the wafer carrier platform 420 to control the movement of the wafer carrier platform 420;

[0100] The control unit 410 is connected to the camera device 430 to control the camera device 430 to take pictures of the first mark and the second mark on the wafer to be aligned;

[0101] The camera device 430 is located above the wafer carrier platform 420.

[0102] Optionally, the wafer transfer system 400 also includes a light source (not shown in the figure), which is a high-brightness point light source that can be directly embedded in the light source interface of the camera lens.

[0103] The following reference Figure 5 The control unit will be introduced.

[0104] Figure 5 A schematic diagram of the control unit provided in an embodiment of this application is shown.

[0105] like Figure 5 As shown, the control unit 410 includes a camera equipment control subunit 411, a database subunit 412, a light source control subunit 413, an image algorithm subunit 414, and a wafer carrier platform control subunit 415.

[0106] The camera equipment control subunit 411 may refer to a camera equipment control software library, which is used to set camera equipment parameters, control the camera equipment to take pictures and transmit images. Setting camera equipment parameters includes setting the camera equipment exposure time and camera equipment gain.

[0107] Database subunit 412 is used to maintain various pre-alignment information, including at least: the size information and type of the wafer to be aligned, image coordinate system description, measurement coordinate system description, and extraction parameters from the image recognition algorithm. The image coordinate system description includes the units and origin of the image coordinate system, and the measurement coordinate system description includes the units and origin of the measurement coordinate system.

[0108] The light source control subunit 413 refers to the light source control software library, which can communicate with the light source through the RS232 interface to control the light source switch and set the light source brightness, providing illumination for the camera equipment to take pictures.

[0109] Image algorithm subunit 414 may refer to an image algorithm software library, which includes at least the transformation relationship between the image coordinate system and the measurement coordinate system.

[0110] The wafer carrier platform control subunit 415 can refer to the wafer carrier platform control software library, which is used to control the high-precision wafer carrier platform to move in the X and Y directions and rotate in the Rz direction, that is, to rotate around the rotation center.

[0111] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 6 As shown, the electronic device 500 includes a processor 510, a memory 520, and a bus 530.

[0112] The memory 520 stores machine-readable instructions executable by the processor 510. When the electronic device 500 is running, the processor 510 and the memory 520 communicate via the bus 530. When the machine-readable instructions are executed by the processor 510, they can perform the operations described above. Figure 1 The specific implementation of the wafer position pre-alignment method in the method embodiment shown can be found in the method embodiment, and will not be repeated here.

[0113] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0114] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0115] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0116] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0117] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0118] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wafer position pre-alignment method, characterized by, The method is applied to a wafer transmission system, the wafer transmission system comprising a wafer carrying platform and a camera device, the wafer carrying platform being provided with a wafer to be aligned, the wafer to be aligned being provided with a first mark and a second mark on a surface thereof, the method comprising: acquiring a first target image of the first mark of the wafer to be aligned, and determining a current position of the first mark; determining an expected current position of the second mark based on the current position of the first mark and a positional relationship between the first mark and the second mark, the positional relationship being a distance between a center point of the first mark and a center point of the second mark; controlling the wafer carrying platform to move based on the expected current position of the second mark, acquiring a second target image of the second mark of the wafer to be aligned, and determining a current position of the second mark; determining a centroid position of the wafer to be aligned and a wafer centroid offset based on the current position of the first mark and the current position of the second mark, and a positional relationship among the first mark, the second mark, and the centroid position of the wafer to be aligned, the wafer centroid offset being an offset between the centroid position of the wafer to be aligned and a target position; controlling the wafer carrying platform to move according to the wafer centroid offset, and moving the centroid position of the wafer to be aligned to the target position; the acquiring of the first target image of the first mark of the wafer to be aligned and the determining of the current position of the first mark comprising: determining an offset of a reference position of the first mark of the wafer to be aligned relative to a position of the camera device based on size information of the wafer to be aligned; controlling the wafer carrying platform to move based on the offset of the reference position of the first mark relative to the position of the camera device, so that the reference position of the first mark of the wafer to be aligned is within a field of view of the camera device; controlling the camera device to take a photo of the first mark of the wafer to be aligned, and acquiring the first target image, so as to analyze the first target image by using an image recognition algorithm, and determine the current position of the first mark; after the controlling of the wafer carrying platform to move according to the wafer centroid offset and the moving of the centroid position of the wafer to be aligned to the target position, the method further comprises: determining the current position of the second mark of the wafer to be aligned again; acquiring a second mark offset between the current position of the second mark of the wafer to be aligned determined again and a reference position of the second mark; comparing the second mark offset with an offset threshold, and determining whether the pre-alignment of the wafer to be aligned is completed.

2. The method of claim 1, wherein, the determining of the offset of the reference position of the first mark of the wafer to be aligned relative to the position of the camera device based on the size information of the wafer to be aligned comprising: determining a first wafer slot corresponding to the wafer to be aligned based on the size information of the wafer to be aligned; acquiring a reference position of the first mark corresponding to the first wafer slot from a database; determining the offset of the reference position of the first mark of the wafer to be aligned relative to the position of the camera device according to the reference position of the first mark and the position of the camera device.

3. The method of claim 1, wherein, the controlling of the wafer carrying platform to move based on the expected current position of the second mark, the acquiring of the second target image of the second mark of the wafer to be aligned, and the determining of the current position of the second mark comprising: determine an offset between the expected current position of the second mark and the camera position based on the expected current position of the second mark; control the wafer carrying platform to move according to the offset between the expected current position of the second mark and the camera position, so that the expected current position of the second mark of the wafer to be aligned is within the field of view of the camera; control the camera to take a second target image of the second mark of the wafer to be aligned; determine the current position of the second mark by analyzing the second target image using an image recognition algorithm.

4. The method according to any one of claims 1 to 3, characterized in that, determine the center position of the wafer to be aligned and the wafer center offset based on the current position of the first mark and the current position of the second mark, and the positional relationship among the first mark, the second mark and the center position of the wafer to be aligned, including: obtain a target position of the center of the wafer to be aligned; determine the center position of the wafer to be aligned based on the current position of the first mark and the current position of the second mark, and the positional relationship among the first mark, the second mark and the center position of the wafer to be aligned; determine the wafer center offset based on the center position of the wafer to be aligned and the target position.

5. The method of claim 1, wherein, The wafer center offset includes an angle offset and a distance offset, and the wafer carrying platform includes a rotating platform. controlling the rotating platform on the wafer carrying platform to rotate according to the angle offset to eliminate the angle offset; controlling the wafer carrying platform to move according to the distance offset to eliminate the distance offset and move the center position of the wafer to be aligned to the target position. The method further includes:

6. The method of claim 1, wherein, obtaining a third target image of the second mark of the wafer to be aligned; determining the current position of the second mark of the wafer to be aligned again by analyzing the third target image using an image recognition algorithm. The method further includes:

7. The method of claim 1, wherein, determining whether the second mark offset is less than the offset threshold; if the second mark offset is less than the offset threshold, completing the pre-alignment of the wafer to be aligned; if the second mark offset is not less than the offset threshold, returning to the step of obtaining the first target image of the first mark of the wafer to be aligned and determining the current position of the first mark. The system includes a control unit, a wafer carrying platform and a camera.

8. A wafer transport system, characterized by, The control unit performs the steps of the wafer position pre-alignment method according to any one of claims 1 to 7. The control unit is connected to the wafer carrying platform to control the movement of the wafer carrying platform. The control unit is connected to the camera to control the camera to take pictures of the first mark and the second mark of the wafer to be aligned. The camera is located above the wafer carrying platform. The method further includes:

9. An electronic device, comprising: ​ A processor, a storage medium storing machine readable instructions executable by the processor, and a bus for communication between the processor and the storage medium when the electronic device is running, the processor executing the machine readable instructions to perform the steps of the wafer position pre-alignment method of any one of claims 1 to 7.

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