Wafer inspection focusing method and apparatus, electronic device, and computer storage medium

Abstract

The present application discloses a wafer inspection focusing method and apparatus, an electronic device, and a computer storage medium. The method comprises: when a target inspection point of a wafer under inspection moves to an imaging center position of an inspection camera, acquiring wafer warpage, corresponding to the target inspection point, obtained by a distance meter performing distance measurement; and on the basis of the wafer warpage corresponding to the target inspection point and an initial focal length of the inspection camera, controlling the inspection camera to perform focusing, so that an image of the wafer under inspection captured by the inspection camera at the target inspection point satisfies a preset inspection requirement. The wafer inspection speed is increased and the wafer inspection precision is improved. In addition, the inspection camera and the distance meter are off-axis and the distance meter is always located ahead of the scanning path of the inspection camera, and an independent optical path is used for implementing focusing using the distance meter, thereby avoiding interference of irregular reflected or scattered light generated in a focusing and distance measurement optical path of the distance meter on an imaging optical path of the inspection camera, and thus improving the stability and reliability of wafer inspection.

Description

Wafer inspection focusing methods, apparatus, electronic equipment and computer storage media Technical Field

[0001] This application relates to the field of wafer inspection technology, and in particular to a wafer inspection focusing method, apparatus, electronic device and computer storage medium. Background Technology

[0002] With the continuous development of semiconductor technology, the precision requirements of semiconductor manufacturing processes are becoming increasingly stringent. The detection capability of wafer inspection equipment determines the stability of precision detection in semiconductor manufacturing processes. Only by accurately locating defects on wafers can the health of the entire production line be guaranteed, thereby improving production efficiency.

[0003] Because wafer surfaces are not perfectly flat, there may be minute height variations. During the scanning or rapid imaging process of wafer inspection equipment, the focus may deviate from the correct position. Defect detection and quality control of wafer surfaces require high-resolution images. If the focus is inaccurate, the image will become blurry, making it difficult to identify minute defects such as microcracks, particles, or other surface inhomogeneities. Summary of the Invention

[0004] This application provides a wafer inspection focusing method, apparatus, electronic device, and computer storage medium. It not only controls the inspection camera to automatically focus based on the wafer warpage corresponding to the target inspection point and the initial focal length of the inspection camera before scanning and photographing the wafer to be inspected at the target inspection point, reducing wafer inspection focusing time and error, and improving wafer inspection speed and accuracy, but also improves wafer inspection stability and reliability by using an independent optical path and focusing with the inspection camera and rangefinder off-axis and the rangefinder always positioned in front of the inspection camera's scanning path, avoiding interference from irregular reflections or scattered light generated by the rangefinder's focusing and ranging optical path on the inspection camera's imaging optical path. The technical solution is as follows:

[0005] In a first aspect, embodiments of this application provide a wafer inspection and focusing method, the method comprising:

[0006] When the target detection point of the wafer to be inspected moves to the imaging center of the inspection camera, the wafer warpage corresponding to the target detection point is obtained; the wafer warpage is obtained by the rangefinder measuring the distance of the target detection point of the wafer to be inspected.

[0007] Based on the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera, the detection camera is controlled to focus so that the wafer image captured by the detection camera at the target detection point meets the preset detection requirements.

[0008] The rangefinder and the detection camera are off-axis, and the rangefinder is always positioned in front of the scanning path of the detection camera.

[0009] In this embodiment, the wafer warpage at the target detection point of the wafer to be inspected is first measured using a rangefinder along the scanning path. Then, before scanning and photographing the wafer at the target detection point, the inspection camera is automatically focused based on the wafer warpage corresponding to the target detection point and the initial focal length of the inspection camera. This ensures that the image of the wafer to be inspected captured by the inspection camera at the target detection point meets preset inspection requirements. This guarantees that the inspection camera can always accurately focus on the surface of the wafer to be inspected, capturing a clear image of the wafer and improving wafer inspection accuracy. It also reduces the focusing time and error during wafer inspection, further improving inspection accuracy. Simultaneously, by positioning the inspection camera and rangefinder off-axis, with the rangefinder always positioned in front of the inspection camera's scanning path, and using an independent optical path and rangefinder focusing, interference from irregular reflections or scattered light generated by the rangefinder's focusing and measuring optical path on the inspection camera's imaging optical path is avoided, improving the stability and reliability of wafer inspection.

[0010] In one possible implementation, when the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera, obtaining the wafer warpage corresponding to the target detection point includes:

[0011] When the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera, the target ranging coordinates of the target detection point corresponding to the rangefinder are determined based on the positional deviation information between the inspection camera and the rangefinder and the current imaging coordinates of the inspection camera.

[0012] The wafer warpage corresponding to the target detection point is determined based on the target ranging coordinates and the focus position compensation relationship. The ranging compensation relationship is generated based on the ranging coordinates of each detection point and the wafer warpage measured at each ranging coordinate during the movement of the wafer to be detected by the ranging instrument.

[0013] In one possible implementation, the above method also includes:

[0014] During the process of moving each detection point of the wafer to be tested to the distance measurement center position of the distance measuring instrument, the distance measuring instrument is controlled to measure the distance of each detection point of the wafer to be tested in sequence to obtain the wafer warpage corresponding to each detection point.

[0015] The above-mentioned focus position compensation relationship is generated based on the wafer warpage corresponding to the measured detection point of the wafer to be tested and the ranging coordinates of the above-mentioned rangefinder corresponding to the measured detection point.

[0016] In one possible implementation, before scanning and photographing the wafer to be inspected at the target detection point, the detection camera is controlled to focus based on the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera, including:

[0017] The target focal length compensation value of the detection camera is determined based on the wafer warpage corresponding to the target detection points.

[0018] The target detection focal length corresponding to the above target detection point is determined based on the above target focal length compensation value and the above detection camera initial focal length.

[0019] Before scanning and photographing the wafer to be inspected at the aforementioned target inspection point, the focal length of the inspection camera is adjusted to the aforementioned target inspection focal length.

[0020] In one possible implementation, the wafer to be tested comprises N layers; where N is a positive integer greater than 1; the method further includes:

[0021] Before scanning and capturing the i-th layer of the wafer to be inspected at the aforementioned target detection point, the detection camera is controlled to focus based on the wafer warpage corresponding to the aforementioned target detection point, the initial focal length of the detection camera, and the target distance between the surface of the first layer and the surface of the i-th layer of the wafer to be inspected, so that the image of the i-th layer of the wafer to be inspected captured by the detection camera at the aforementioned target detection point meets the preset detection requirements; i is a positive integer greater than 1 and less than or equal to N.

[0022] In one possible implementation, the different detection points of the wafer to be inspected correspond to different imaging coordinates of the detection camera and different ranging coordinates of the rangefinder; the positional deviations between the imaging coordinates of the detection camera and the ranging coordinates of the rangefinder for the different detection points of the wafer to be inspected are the same.

[0023] In one possible implementation, during the process of the wafer to be inspected moving along a preset detection path, the ranging center position of the ranging instrument is always located before the imaging center position of the detection camera. The distance between the ranging center position and the imaging center position is greater than a first threshold and less than a second threshold, and the second threshold is greater than the first threshold.

[0024] In this embodiment, during the movement of the wafer under inspection along a preset inspection path, the ranging center of the rangefinder is always positioned before the imaging center of the inspection camera. This ensures that the inspection camera has measured the warpage corresponding to each inspection point before scanning and capturing images, guaranteeing that the inspection camera can automatically focus at each inspection point based on the warpage, thus ensuring the success rate and effectiveness of wafer inspection focusing. To avoid interference from irregular reflections or scattered light generated by the rangefinder's focusing and ranging optical path on the inspection camera's imaging optical path, the distance between the ranging center and the imaging center should be set to be greater than a first threshold. This ensures that the rangefinder's focusing and ranging optical path and the inspection camera's corresponding imaging optical path are independent and do not interfere with each other. Simultaneously, to avoid an excessively large distance between the ranging center and the imaging center causing the inspection camera's actual scanning path to be too large and affecting the inspection speed, the distance between the ranging center and the imaging center should be set to be less than a second threshold. This ensures that while achieving automatic focusing during wafer inspection, it also guarantees a certain degree of efficiency in wafer inspection.

[0025] Secondly, embodiments of this application provide a wafer inspection focusing device, the wafer inspection focusing device comprising:

[0026] The acquisition module is used to acquire the wafer warpage corresponding to the target detection point when the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera; the wafer warpage is obtained by the rangefinder measuring the distance of the target detection point of the wafer to be inspected.

[0027] The first focusing module is used to control the detection camera to focus according to the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera before scanning and taking pictures of the wafer to be inspected at the target detection point, so that the image of the wafer to be inspected taken by the detection camera at the target detection point meets the preset detection requirements.

[0028] The rangefinder and the detection camera are off-axis, and the rangefinder is always positioned in front of the scanning path of the detection camera.

[0029] In one possible implementation, the above-mentioned acquisition module includes:

[0030] The first determining unit is used to determine the target ranging coordinates of the target detection point corresponding to the rangefinder based on the positional deviation information between the detection camera and the rangefinder and the current imaging coordinates of the detection camera when the target detection point of the wafer to be inspected moves to the imaging center position of the detection camera.

[0031] The second determining unit is used to determine the wafer warpage corresponding to the target detection point based on the target ranging coordinates and the focusing position compensation relationship. The ranging compensation relationship is generated based on the ranging coordinates corresponding to each detection point and the wafer warpage measured at each ranging coordinate during the movement of the wafer to be detected by the ranging instrument.

[0032] In one possible implementation, the wafer inspection focusing device further includes:

[0033] The ranging module is used to control the ranging instrument to measure the distance of each detection point of the wafer to be tested in sequence as the wafer to be tested moves to the ranging center position of the ranging instrument in sequence, so as to obtain the wafer warpage corresponding to each detection point.

[0034] The generation module is used to generate the focus position compensation relationship based on the wafer warpage corresponding to the measured detection point of the wafer to be tested and the ranging coordinates of the rangefinder corresponding to the measured detection point.

[0035] In one possible implementation, the first focusing module mentioned above includes:

[0036] The third determining unit is used to determine the target focal length compensation value corresponding to the detection camera based on the wafer warpage corresponding to the target detection point.

[0037] The fourth determining unit is used to determine the target detection focal length corresponding to the target detection point based on the target focal length compensation value and the initial focal length of the detection camera.

[0038] The adjustment unit is used to adjust the focal length of the inspection camera to the target inspection focal length before scanning and photographing the wafer to be inspected at the target inspection point.

[0039] In one possible implementation, the wafer to be inspected comprises N layers; N is a positive integer greater than 1; the wafer inspection focusing device further includes:

[0040] The second focusing module is used to control the detection camera to focus before scanning and capturing the i-th layer of the wafer to be inspected at the target detection point, based on the wafer warpage corresponding to the target detection point, the initial focal length of the detection camera, and the target distance between the surface of the first layer and the surface of the i-th layer of the wafer to be inspected, so that the image of the i-th layer of the wafer to be inspected captured by the detection camera at the target detection point meets the preset detection requirements; where i is a positive integer greater than 1 and less than or equal to N.

[0041] In one possible implementation, the different detection points of the wafer to be inspected correspond to different imaging coordinates of the detection camera and different ranging coordinates of the rangefinder; the positional deviations between the imaging coordinates of the detection camera and the ranging coordinates of the rangefinder for the different detection points of the wafer to be inspected are the same.

[0042] In one possible implementation, during the process of the wafer to be inspected moving along a preset detection path, the ranging center position of the ranging instrument is always located before the imaging center position of the detection camera. The distance between the ranging center position and the imaging center position is greater than a first threshold and less than a second threshold, and the second threshold is greater than the first threshold.

[0043] Thirdly, embodiments of this application provide an electronic device, including: a processor and a memory; wherein the memory stores a computer program, the computer program being adapted to be loaded by the processor and execute the method steps provided by the first aspect of the embodiments of this application or any possible implementation thereof.

[0044] Fourthly, embodiments of this application provide a computer storage medium storing a plurality of instructions adapted for loading by a processor and executing the method steps provided by the first aspect of the embodiments of this application or any possible implementation thereof.

[0045] It is understood that the wafer inspection and focusing device provided in the second aspect, the electronic device provided in the third aspect, and the computer storage medium provided in the fourth aspect are all used to execute the wafer inspection and focusing method provided in the first aspect or any implementation of the first aspect. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the wafer inspection and focusing method provided in the first aspect or any implementation of the first aspect, and will not be repeated here.

[0046] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 is a schematic diagram of the architecture of a wafer inspection focusing system provided in an exemplary embodiment of this application;

[0049] Figure 2 is a schematic flowchart of a wafer inspection focusing method provided in an exemplary embodiment of this application;

[0050] Figure 3 is a schematic diagram of an imaging coordinate and a ranging coordinate provided in an exemplary embodiment of this application;

[0051] Figure 4 is a schematic diagram of the implementation process of controlling a detection camera to focus, provided by an exemplary embodiment of this application;

[0052] Figure 5 is a flowchart illustrating another wafer inspection and focusing method provided in an exemplary embodiment of this application;

[0053] Figure 6 is a schematic diagram of a wafer inspection focusing device provided in an exemplary embodiment of this application;

[0054] Figure 7 is a schematic diagram of the structure of an electronic device provided in an exemplary embodiment of this application. Detailed Implementation

[0055] To make the features and advantages of this application more apparent and understandable, the technical solutions in 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. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0056] The terms "first," "second," "third," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0057] Please refer to Figure 1 below, which is a schematic diagram of the architecture of a wafer inspection focusing system provided in an exemplary embodiment of this specification. As shown in Figure 1, the wafer inspection focusing system includes: a processor 110, an inspection camera 120, a rangefinder 130, and a wafer inspection stage 140. Wherein:

[0058] The wafer inspection stage 140 is used to carry the wafer 150 to be inspected and to move the wafer 150 to be inspected along a preset inspection path.

[0059] The inspection camera 120 may include, but is not limited to, a high-resolution image sensor for scanning and capturing images of the wafer 150 to be inspected on the wafer inspection stage 140, thereby obtaining images of the wafer 150 corresponding to each inspection point.

[0060] The rangefinder 130 can be, but is not limited to, a stationary laser rangefinder, ultrasonic rangefinder, or infrared rangefinder, used to measure the warpage of the surface of the wafer 150 to be inspected on the wafer inspection stage 140. The rangefinder 130 is off-axis from the inspection camera 120. By using an independent optical path and focusing with the rangefinder, the interference of irregular reflections or scattered light generated by the focusing and measuring optical path of the rangefinder on the imaging optical path of the inspection camera is avoided, thereby improving the stability and reliability of wafer inspection. Furthermore, the rangefinder 130 is always located in front of the scanning path of the inspection camera 120 to ensure that the inspection camera 120 obtains the wafer warpage corresponding to each inspection point before scanning and capturing images of each inspection point of the wafer 150 to achieve automatic focusing.

[0061] The processor 110 is connected to the inspection camera 120, the rangefinder 130, and the wafer inspection stage 140, respectively. It can be used to control the wafer 150 to be inspected to move along a preset inspection path. When the target inspection point of the wafer 150 is moved to the imaging center of the inspection camera 120, the processor 110 can obtain the wafer warpage corresponding to the target inspection point obtained by the rangefinder 130. Before scanning and taking pictures of the wafer 150 at the target inspection point, the processor 110 controls the inspection camera 120 to focus according to the wafer warpage corresponding to the target inspection point and the initial focal length of the inspection camera 120, so that the image of the wafer to be inspected taken by the inspection camera 120 at the target inspection point meets the preset inspection requirements.

[0062] Referring to Figure 1, and taking the wafer inspection and focusing process performed by the processor of the wafer inspection and focusing system as an example, we will now introduce a wafer inspection and focusing method provided by an exemplary embodiment of this application. Please refer to Figure 2 for details, which is a flowchart illustrating a wafer inspection and focusing method provided by an exemplary embodiment of this application. As shown in Figure 2, the wafer inspection and focusing method may include the following steps:

[0063] S201, when the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera, the wafer warpage corresponding to the target detection point is obtained. The wafer warpage is obtained by the rangefinder measuring the distance of the target detection point of the wafer to be inspected.

[0064] Specifically, the aforementioned wafer warpage is used to characterize the degree of bending or twisting of the wafer under test due to the accumulation of thermomechanical stress during processing or packaging.

[0065] Optionally, when the target detection point of the wafer to be inspected moves to the imaging center of the inspection camera, the target ranging coordinates of the rangefinder corresponding to the target detection point can be determined first based on the positional deviation information between the inspection camera and the rangefinder and the current imaging coordinates of the inspection camera. The aforementioned positional deviation information may include, but is not limited to, the positional coordinate deviation value between the inspection camera and the rangefinder in the wafer scanning direction. When the target detection point of the wafer to be inspected moves to the imaging center of the inspection camera, the target ranging scanning coordinates of the rangefinder corresponding to the target detection point can be determined based on, but is not limited to, the positional coordinate deviation value between the inspection camera and the rangefinder in the wafer scanning direction and the current imaging scanning coordinates of the inspection camera in the wafer scanning direction. There is no positional coordinate deviation between the inspection camera and the rangefinder in the wafer turning direction; that is, the current imaging turning coordinates of the inspection camera in the wafer turning direction are equal to the target ranging turning coordinates of the rangefinder in the wafer turning direction. The aforementioned target ranging coordinates can be composed of the aforementioned target ranging scanning coordinates and target ranging turning coordinates.

[0066] Then, the wafer warpage corresponding to the target detection point is determined based on the target ranging coordinates and the focus position compensation relationship. The above ranging compensation relationship is generated based on the ranging coordinates of each detection point and the wafer warpage measured at each ranging coordinate during the movement of the rangefinder over the wafer to be inspected.

[0067] In some possible embodiments, multiple detection points for scanning and detection are pre-defined on the wafer to be inspected. As each detection point on the wafer to be inspected moves sequentially to the distance measurement center of the rangefinder, the rangefinder can be controlled to measure the distance to each detection point sequentially, obtaining the wafer warpage corresponding to each detection point. Then, a focus position compensation relationship is generated based on the wafer warpage corresponding to the measured detection points and the distance measurement coordinates of the rangefinder corresponding to the measured detection points, so that the inspection camera can be automatically focused subsequently based on this focus position compensation relationship.

[0068] For example, as shown in Figure 3, since the rangefinder 130 and the detection camera 120 are off-axis and the rangefinder 130 is always located in front of the scanning path of the detection camera 120, during the leftward movement of the wafer to be inspected 150, its detection point 310 will first move to the ranging center position of the rangefinder 130 (as shown in the left figure of Figure 3). The rangefinder 130 measures the distance on the surface of the detection point 310 of the wafer to be inspected to obtain the corresponding warpage d(x1,y1). At this time, the ranging scanning coordinates corresponding to the rangefinder 130 are (x1,y1), where x1 is the ranging scanning coordinate corresponding to the rangefinder 130 measuring the distance on the surface of the detection point 310 of the wafer to be inspected 150, and y1 is the ranging crossover coordinate corresponding to the rangefinder 130 measuring the distance on the surface of the detection point 310 of the wafer to be inspected 150. After the rangefinder 130 measures the warp d(x1,y1) corresponding to the detection point 310, it will also associate and store the ranging scan coordinates (x1,y1) corresponding to the detection point 310 with the warp d(x1,y1). For example, but not limited to, generating a focus position compensation relationship based on the ranging scan coordinates (x1,y1) corresponding to the detection point 310 and the warp d(x1,y1).

[0069] Then, the detection point 310 of the wafer 150 to be inspected will move to the imaging center position of the inspection camera 120 (as shown in the right figure of Figure 3). The inspection camera 120 needs to focus at the detection point 310 and scan and capture the wafer 150 to obtain the corresponding image of the wafer to be inspected. At this time, the current imaging coordinates of the inspection camera 120 are (x0, y1), where x0 is the current imaging scanning coordinate of the inspection camera 120 when scanning and capturing the wafer 150 to be inspected at the detection point 310, and y1 is the current imaging wrapping coordinate of the inspection camera 120 when scanning and capturing the wafer 150 to be inspected at the detection point 310. Furthermore, as shown in the right figure of Figure 3, when the detection point 310 of the wafer 150 to be inspected moves to the imaging center position of the inspection camera 120, the next detection point 320 of the wafer 150 to be inspected will move to the ranging center position of the rangefinder 130 to measure the distance, obtain the corresponding warpage d(x2,y1), and associate the ranging scanning coordinates (x2,y1) corresponding to the detection point 320 with the warpage d(x2,y1) and store them, that is, update the above-mentioned focus position compensation relationship. In other words, the focus position compensation relationship corresponding to the wafer 150 to be inspected will be updated as the number of detection points measured by the rangefinder 130 is updated.

[0070] Because there is a position coordinate deviation of 330 between the same detection camera 120 and rangefinder 130 in the wafer scanning direction, and because the current imaging coordinates of the detection camera 120 (x0, y1) and the ranging scanning coordinates of the rangefinder 130 (x1, y1) are different for the same detection point 310, in order to obtain the warpage at the detection point 310, it is necessary to first map the current imaging coordinates (x0, y1) of the detection camera 120. For example, but not limited to, based on the position coordinate deviation of 330 between the detection camera 120 and the rangefinder 130 in the wafer scanning direction (i.e., D = x2 - x0) and the current imaging scanning coordinate x0 of the detection camera 120 in the wafer scanning direction, the ranging scanning coordinates of the rangefinder 130 at the detection point 310 are determined to be x0 + D (i.e., x1), thereby determining the ranging coordinates of the rangefinder 130 at the detection point 310 as (x0 + D, y1), i.e. (x1, y1). Finally, the corresponding warp d(x1,y1) can be found in the above focus position compensation relationship based on (x1,y1) at the detection point 310.

[0071] For example, the focus position compensation relationship corresponding to the wafer to be inspected can be, but is not limited to, as shown in Table 1:

[0072] Table 1. Relationship between the ranging coordinates of each detection point and the wafer warpage during the movement of the wafer under test.

[0073] x yx1...xmy1d(1,1)...d(m,1)...ynd(1,n)...d(m,n)

[0074] Where xm represents the ranging scan coordinate of the m-th detection point in the wafer scanning direction, yn represents the ranging and traversing coordinate of the n-th detection point in the wafer traversing direction, and d(m,n) represents the warpage corresponding to the detection point with ranging coordinates (m,n).

[0075] Optionally, when the target detection point of the wafer to be inspected moves to the imaging center of the inspection camera, the wafer warpage corresponding to the target detection point can be directly found from the detection point compensation relationship based on the identifier of the target detection point. The aforementioned detection point compensation relationship is used to characterize the correspondence between the identifier of each detection point of the wafer to be inspected and the warpage obtained by measuring the surface of the wafer to be inspected at each detection point using a rangefinder.

[0076] Understandably, different detection points on the wafer under inspection correspond to different imaging coordinates of the detection camera and different ranging coordinates of the rangefinder. The positional deviation between the imaging coordinates of the detection camera and the ranging coordinates of the rangefinder is the same for different detection points on the wafer. The scanning frequency of the detection camera is the same as the focusing and ranging frequency of the rangefinder.

[0077] In some possible embodiments, during the movement of the wafer under inspection along a preset inspection path, the ranging center of the rangefinder is always positioned before the imaging center of the inspection camera. This ensures that the inspection camera has measured the warpage corresponding to each inspection point before scanning and capturing images, guaranteeing that the inspection camera can automatically focus based on the warpage at each inspection point, thus ensuring the success rate and effectiveness of wafer inspection focusing. To avoid interference from irregular reflections or scattered light generated by the rangefinder's focusing and ranging optical path on the inspection camera's imaging optical path, the distance between the ranging center and the imaging center should be set to be greater than a first threshold. This ensures that the rangefinder's focusing and ranging optical path and the corresponding imaging optical path of the inspection camera are independent and do not interfere with each other. Simultaneously, to avoid an excessively large distance between the ranging center and the imaging center causing the actual scanning path of the inspection camera to be too large and affecting the inspection speed, the distance between the ranging center and the imaging center should be set to be less than a second threshold. This ensures that while achieving automatic focusing during wafer inspection, it also guarantees a certain degree of efficiency in wafer inspection. The second threshold is greater than the first threshold.

[0078] Next, please refer to Figure 2. As shown in Figure 2, in step S201 above, after the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera and the wafer warpage corresponding to the target detection point is obtained, the wafer inspection focusing method further includes:

[0079] S202, the detection camera is controlled to focus according to the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera, so that the image of the wafer to be detected captured by the detection camera at the target detection point meets the preset detection requirements.

[0080] Specifically, the rangefinder and the detection camera are off-axis, and the rangefinder is always positioned in front of the scanning path of the detection camera. The preset detection requirements may include, but are not limited to, a sharpness greater than a threshold corresponding to the image of the wafer to be detected. As shown in Figure 4, the implementation process of S202, which controls the detection camera to focus based on the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera, may include, but is not limited to:

[0081] S401 determines the target focal length compensation value of the detection camera based on the wafer warpage corresponding to the target detection point.

[0082] Specifically, after obtaining the wafer warpage corresponding to the target detection point, the wafer warpage corresponding to the target detection point can be converted into a target focal length compensation value for the detection camera based on the pre-set correspondence between the focal length compensation value of the detection camera and the wafer warpage measured by the rangefinder (e.g., but not limited to conversion functions, conversion formulas, mapping tables, etc.). This target focal length compensation value is used to characterize the distance that the focal length of the detection camera needs to be adjusted at the target detection point of the wafer to be inspected.

[0083] S402 determines the target detection focal length corresponding to the target detection point based on the target focal length compensation value and the initial focal length of the detection camera.

[0084] Specifically, the initial focal length can be the focal length at which the detection camera can capture the clearest image when the distance between the detection camera and the surface of the wafer to be detected is at a preset standard distance, or it can be a focal length preset based on the distance between the detection camera and the wafer to be detected. This embodiment of the application does not limit this. After obtaining the target focal length compensation value at the target detection point, the target focal length compensation value can be directly summed with the initial focal length of the detection camera to obtain the target detection focal length corresponding to the target detection point.

[0085] S403: Before scanning and photographing the wafer to be inspected at the target inspection point, adjust the focus of the inspection camera to the target inspection focus.

[0086] Specifically, before scanning and photographing the wafer to be inspected at the target inspection point, the focus of the inspection camera needs to be adjusted to the target inspection focus so that the image of the wafer to be inspected captured by the inspection camera at the target inspection point meets the preset inspection requirements.

[0087] In this embodiment, the wafer warpage at the target detection point of the wafer to be inspected is first measured using a rangefinder along the scanning path. Then, before scanning and photographing the wafer at the target detection point, the inspection camera is automatically focused based on the wafer warpage corresponding to the target detection point and the initial focal length of the inspection camera. This ensures that the image of the wafer to be inspected captured by the inspection camera at the target detection point meets preset inspection requirements. This guarantees that the inspection camera can always accurately focus on the surface of the wafer to be inspected, capturing a clear image of the wafer and improving wafer inspection accuracy. It also reduces the focusing time and error during wafer inspection, further improving inspection accuracy. Simultaneously, by positioning the inspection camera and rangefinder off-axis, with the rangefinder always positioned in front of the inspection camera's scanning path, and using an independent optical path and rangefinder focusing, interference from irregular reflections or scattered light generated by the rangefinder's focusing and measuring optical path on the inspection camera's imaging optical path is avoided, improving the stability and reliability of wafer inspection.

[0088] Next, please refer to Figure 5, which is a flowchart illustrating another wafer inspection and focusing method provided in an exemplary embodiment of this application. As shown in Figure 5, the wafer inspection and focusing method may include the following steps:

[0089] S501, when the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera, the wafer warpage corresponding to the target detection point is obtained. The wafer warpage is obtained by the rangefinder measuring the distance of the target detection point of the wafer to be inspected.

[0090] Specifically, S501 is the same as S201, and will not be repeated here.

[0091] S502, before scanning and capturing the i-th layer of the wafer to be inspected at the target inspection point, the inspection camera is controlled to focus according to the wafer warpage corresponding to the target inspection point, the initial focal length of the inspection camera, and the target distance between the surface of the first layer and the surface of the i-th layer of the wafer to be inspected, so that the image of the i-th layer of the wafer to be inspected captured by the inspection camera at the target inspection point meets the preset inspection requirements.

[0092] Specifically, the wafer to be inspected comprises N layers, where N is a positive integer greater than 1. When it is necessary to inspect the i-th layer below the first layer of the wafer, before scanning and capturing the i-th layer of the wafer at the target inspection point, the target inspection focal length corresponding to the i-th layer at the target inspection point can be directly determined based on the wafer warpage corresponding to the target inspection point, the initial focal length of the inspection camera, and the target distance between the surface of the first layer and the surface of the i-th layer of the wafer. This eliminates the need to readjust the rangefinder for distance measurement and the need for manual refocusing of the inspection camera. The camera can be directly controlled to focus based on the target inspection focal length corresponding to the i-th layer at the target inspection point, ensuring that the image of the i-th layer of the wafer captured by the inspection camera at the target inspection point meets the preset inspection requirements, thus improving the flexibility, efficiency, and convenience of wafer inspection focusing. Here, i is a positive integer greater than 1 and less than or equal to N.

[0093] Next, please refer to Figure 6, which is a schematic diagram of a wafer inspection focusing device provided in an exemplary embodiment of this application. As shown in Figure 6, the wafer inspection focusing device 600 includes:

[0094] The acquisition module 610 is used to acquire the wafer warpage corresponding to the target detection point when the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera; the wafer warpage is obtained by the rangefinder measuring the distance of the target detection point of the wafer to be inspected.

[0095] The first focusing module 620 is used to control the detection camera to focus according to the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera, so that the wafer image to be detected captured by the detection camera at the target detection point meets the preset detection requirements.

[0096] The rangefinder and the detection camera are off-axis, and the rangefinder is always positioned in front of the scanning path of the detection camera.

[0097] In one possible implementation, the acquisition module 610 includes:

[0098] The first determining unit is used to determine the target ranging coordinates of the target detection point corresponding to the rangefinder based on the positional deviation information between the detection camera and the rangefinder and the current imaging coordinates of the detection camera when the target detection point of the wafer to be inspected moves to the imaging center position of the detection camera.

[0099] The second determining unit is used to determine the wafer warpage corresponding to the target detection point based on the target ranging coordinates and the focusing position compensation relationship. The ranging compensation relationship is generated based on the ranging coordinates corresponding to each detection point and the wafer warpage measured at each ranging coordinate during the movement of the wafer to be detected by the ranging instrument.

[0100] In one possible implementation, the wafer inspection focusing device 600 further includes:

[0101] The ranging module is used to control the ranging instrument to measure the distance of each detection point of the wafer to be tested in sequence as the wafer to be tested moves to the ranging center position of the ranging instrument in sequence, so as to obtain the wafer warpage corresponding to each detection point.

[0102] The generation module is used to generate the focus position compensation relationship based on the wafer warpage corresponding to the measured detection point of the wafer to be tested and the ranging coordinates of the rangefinder corresponding to the measured detection point.

[0103] In one possible implementation, the first focusing module 620 described above includes:

[0104] The third determining unit is used to determine the target focal length compensation value corresponding to the detection camera based on the wafer warpage corresponding to the target detection point.

[0105] The fourth determining unit is used to determine the target detection focal length corresponding to the target detection point based on the target focal length compensation value and the initial focal length of the detection camera.

[0106] The adjustment unit is used to adjust the focal length of the inspection camera to the target inspection focal length before scanning and photographing the wafer to be inspected at the target inspection point.

[0107] In one possible implementation, the wafer to be inspected comprises N layers; N is a positive integer greater than 1; the wafer inspection focusing device 600 further includes:

[0108] The second focusing module is used to control the detection camera to focus before scanning and capturing the i-th layer of the wafer to be inspected at the target detection point, based on the wafer warpage corresponding to the target detection point, the initial focal length of the detection camera, and the target distance between the surface of the first layer and the surface of the i-th layer of the wafer to be inspected, so that the image of the i-th layer of the wafer to be inspected captured by the detection camera at the target detection point meets the preset detection requirements; where i is a positive integer greater than 1 and less than or equal to N.

[0109] In one possible implementation, the different detection points of the wafer to be inspected correspond to different imaging coordinates of the detection camera and different ranging coordinates of the rangefinder; the positional deviations between the imaging coordinates of the detection camera and the ranging coordinates of the rangefinder for the different detection points of the wafer to be inspected are the same.

[0110] In one possible implementation, during the process of the wafer to be inspected moving along a preset detection path, the ranging center position of the ranging instrument is always located before the imaging center position of the detection camera. The distance between the ranging center position and the imaging center position is greater than a first threshold and less than a second threshold, and the second threshold is greater than the first threshold.

[0111] The division of modules in the above-described wafer inspection and focusing device is for illustrative purposes only. In other embodiments, the wafer inspection and focusing device can be divided into different modules as needed to complete all or part of the functions of the wafer inspection and focusing device. The implementation of each module in the wafer inspection and focusing device provided in this application embodiment can be in the form of a computer program. This computer program can run on an electronic device. The program modules constituted by this computer program can be stored in the memory of the electronic device. When the computer program is executed by a processor, it implements all or part of the steps of the wafer inspection and focusing method described in this application embodiment.

[0112] Please refer to Figure 7, which is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. As shown in Figure 7, the electronic device 700 includes: at least one processor 710, at least one communication bus 720, user interface 730, at least one network interface 740, memory 750, detection camera 760, and rangefinder 770.

[0113] The communication bus 720 can be used to realize the connection and communication of the above components.

[0114] The user interface 730 may include a display screen and a camera. Optionally, the user interface 730 may also include a standard wired interface and a wireless interface.

[0115] The network interface 740 may include a Bluetooth module, a Near Field Communication (NFC) module, a Wireless Fidelity (Wi-Fi) module, etc.

[0116] The inspection camera 760 may include, but is not limited to, a high-resolution image sensor, for scanning and capturing images of the wafer to be inspected, thereby obtaining images of the wafer to be inspected corresponding to each inspection point.

[0117] Among them, the rangefinder 770 can be, but is not limited to, a laser rangefinder, an ultrasonic rangefinder, an infrared rangefinder, etc., and is used to measure the warpage of the surface of the wafer to be inspected;

[0118] The processor 710 may include one or more processing cores. The processor 710 connects to various parts within the electronic device 700 using various interfaces and lines, and performs various functions and processes data by running or executing instructions, programs, code sets, or instruction sets stored in the memory 750, and by calling data stored in the memory 750. Optionally, the processor 710 may be implemented using at least one hardware form of Digital Signal Processing (DSP), Field-Programmable Gate Array (FPGA), or Programmable Logic Array (PLA). The processor 710 may integrate one or a combination of several of the following: a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), and a modem. The CPU primarily handles the operating system, user interface, and applications; the GPU is responsible for rendering and drawing the content required for display; and the modem handles wireless communication. It is understood that the modem may also not be integrated into the processor 710 and may be implemented as a separate chip.

[0119] The memory 750 may include random access memory (RAM) or read-only memory (ROM). Optionally, the memory 750 may include a non-transitory computer-readable medium. The memory 750 may be used to store instructions, programs, code, code sets, or instruction sets. The memory 750 may include a program storage area and a data storage area. The program storage area may store instructions for implementing an operating system, instructions for at least one function (such as wafer inspection focusing function, ranging function, acquisition function, etc.), instructions for implementing the above-described method embodiments, etc.; the data storage area may store data involved in the above-described method embodiments, etc. The memory 750 may also be at least one storage device located remotely from the aforementioned processor 710. As shown in FIG7, the memory 750, as a computer storage medium, may include an operating system, a network communication module, a user interface module, and program instructions.

[0120] Specifically, the processor 710 can be used to call program instructions stored in the memory 750 and perform the following operations:

[0121] When the target detection point of the wafer to be inspected moves to the imaging center of the inspection camera, the wafer warpage corresponding to the target detection point is obtained; the wafer warpage is obtained by the rangefinder measuring the distance of the target detection point of the wafer to be inspected.

[0122] The detection camera is controlled to focus based on the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera, so that the wafer image captured by the detection camera at the target detection point meets the preset detection requirements; wherein, the rangefinder and the detection camera are off-axis and the rangefinder is always located in front of the scanning path of the detection camera.

[0123] In some possible embodiments, when the processor 710 executes the above-described method of obtaining the wafer warpage corresponding to the target detection point when the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera, it is specifically used to perform the following:

[0124] When the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera, the target ranging coordinates of the target detection point corresponding to the rangefinder are determined based on the positional deviation information between the inspection camera and the rangefinder and the current imaging coordinates of the inspection camera.

[0125] The wafer warpage corresponding to the target detection point is determined based on the target ranging coordinates and the focus position compensation relationship. The ranging compensation relationship is generated based on the ranging coordinates of each detection point and the wafer warpage measured at each ranging coordinate during the movement of the wafer to be detected by the ranging instrument.

[0126] In some possible embodiments, the processor 710 described above is also used to perform:

[0127] During the process of moving each detection point of the wafer to be tested sequentially to the distance measurement center position of the distance measuring instrument, the distance measuring instrument is controlled to measure the distance of each detection point of the wafer to be tested sequentially to obtain the wafer warpage corresponding to each detection point.

[0128] The above-mentioned focus position compensation relationship is generated based on the wafer warpage corresponding to the measured detection point of the wafer to be tested and the ranging coordinates of the above-mentioned rangefinder corresponding to the measured detection point.

[0129] In some possible embodiments, when the processor 710 executes the above-described control of the detection camera to focus based on the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera, it is specifically used to perform the following:

[0130] The target focal length compensation value corresponding to the detection camera is determined based on the wafer warpage corresponding to the target detection points.

[0131] The target detection focal length corresponding to the above target detection point is determined based on the above target focal length compensation value and the above detection camera initial focal length.

[0132] Before scanning and photographing the wafer to be inspected at the aforementioned target inspection point, the focal length of the inspection camera is adjusted to the aforementioned target inspection focal length.

[0133] In some possible embodiments, the wafer to be tested comprises N layers; N is a positive integer greater than 1; the processor 710 is further configured to perform:

[0134] Before scanning and capturing the i-th layer of the wafer to be inspected at the aforementioned target detection point, the detection camera is controlled to focus based on the wafer warpage corresponding to the aforementioned target detection point, the initial focal length of the detection camera, and the target distance between the surface of the first layer and the surface of the i-th layer of the wafer to be inspected, so that the image of the i-th layer of the wafer to be inspected captured by the detection camera at the aforementioned target detection point meets the preset detection requirements; i is a positive integer greater than 1 and less than or equal to N.

[0135] In some possible embodiments, the different detection points of the wafer to be inspected correspond to different imaging coordinates of the detection camera and different ranging coordinates of the rangefinder; the positional deviations between the imaging coordinates of the detection camera and the ranging coordinates of the rangefinder are the same for the different detection points of the wafer to be inspected.

[0136] In some possible embodiments, during the process of the wafer to be tested moving along the preset detection path, the ranging center position of the ranging instrument is always located before the imaging center position of the detection camera, and the distance between the ranging center position and the imaging center position is greater than a first threshold and less than a second threshold, wherein the second threshold is greater than the first threshold.

[0137] This application embodiment also provides a computer storage medium storing instructions that, when run on a computer or processor, cause the computer or processor to perform one or more steps of any of the above methods. If the constituent modules of the above-described wafer inspection and focusing device are implemented as software functional units and sold or used as independent products, they can be stored in the storage medium.

[0138] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0139] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks. Unless otherwise specified, the technical features of this embodiment and its implementation can be combined arbitrarily.

[0140] The embodiments described above are merely preferred embodiments of this application and are not intended to limit the scope of this application. Any modifications and improvements made by those skilled in the art to the technical solutions of this application without departing from the spirit of this application should fall within the protection scope defined by the claims of this application.

Claims

1. A wafer inspection focusing method, characterized in that, The method includes: When the target detection point of the wafer to be inspected moves to the imaging center of the inspection camera, the wafer warpage corresponding to the target detection point is obtained; the wafer warpage is obtained by measuring the distance of the target detection point of the wafer to be inspected by a rangefinder. The detection camera is controlled to focus based on the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera, so that the wafer image captured by the detection camera at the target detection point meets the preset detection requirements. The rangefinder is off-axis from the detection camera, and the rangefinder is always positioned in front of the scanning path of the detection camera.

2. The method of claim 1, wherein, When the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera, the wafer warpage corresponding to the target detection point is obtained, including: When the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera, the target ranging coordinates of the target detection point corresponding to the ranging instrument are determined according to the positional deviation information between the inspection camera and the rangefinder and the current imaging coordinates of the inspection camera. The wafer warpage corresponding to the target detection point is determined based on the target ranging coordinates and the focus position compensation relationship; the ranging compensation relationship is generated based on the ranging coordinates of each detection point and the wafer warpage measured at each ranging coordinate during the movement of the wafer to be detected by the rangefinder.

3. The method of claim 2, wherein, The method further includes: During the process of each detection point of the wafer to be inspected moving sequentially to the distance measurement center position of the distance measuring instrument, the distance measuring instrument is controlled to measure the distance of each detection point of the wafer to be inspected sequentially to obtain the wafer warpage corresponding to each detection point. The focus position compensation relationship is generated based on the wafer warpage corresponding to the measured detection point of the wafer to be tested and the ranging coordinates of the rangefinder corresponding to the measured detection point.

4. The method of claim 1, wherein, The step of controlling the detection camera to focus based on the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera includes: The target focal length compensation value of the detection camera is determined based on the wafer warpage corresponding to the target detection point. The target detection focal length corresponding to the target detection point is determined based on the target focal length compensation value and the initial focal length of the detection camera; Before scanning and photographing the wafer to be inspected at the target detection point, the focal length of the inspection camera is adjusted to the target detection focal length.

5. The method of claim 1, wherein, The wafer to be tested comprises N layers; N is a positive integer greater than 1; the method further includes: Before scanning and capturing the i-th layer of the wafer to be inspected at the target detection point, the detection camera is controlled to focus according to the wafer warpage corresponding to the target detection point, the initial focal length of the detection camera, and the target distance between the surface of the first layer and the surface of the i-th layer of the wafer to be inspected, so that the image of the i-th layer of the wafer to be inspected captured by the detection camera at the target detection point meets the preset detection requirements; where i is a positive integer greater than 1 and less than or equal to N.

6. The method according to any one of claims 1 to 5, wherein, The different detection points of the wafer under test correspond to different imaging coordinates of the detection camera and different ranging coordinates of the rangefinder; the positional deviations between the imaging coordinates of the detection camera and the ranging coordinates of the rangefinder are the same for the different detection points of the wafer under test.

7. The method of claim 1, wherein, During the process of the wafer to be tested moving along the preset detection path, the distance measuring center of the distance measuring instrument is always located in front of the imaging center of the detection camera. The distance between the distance measuring center and the imaging center is greater than a first threshold and less than a second threshold, and the second threshold is greater than the first threshold.

8. A wafer inspection focusing device, characterized in that, include: The acquisition module is used to acquire the wafer warpage corresponding to the target detection point when the target detection point of the wafer to be inspected moves to the imaging center position of the inspection camera. The wafer warpage is obtained by measuring the distance of the target detection point of the wafer to be inspected using a rangefinder; The first focusing module is used to control the detection camera to focus according to the wafer warpage corresponding to the target detection point and the initial focal length of the detection camera, so that the wafer image to be detected captured by the detection camera at the target detection point meets the preset detection requirements. The rangefinder is off-axis from the detection camera, and the rangefinder is always positioned in front of the scanning path of the detection camera.

9. An electronic device, comprising: include: A processor and a memory; wherein the memory stores executable program code, and the processor runs a program corresponding to the executable program code by reading the executable program code stored in the memory, for performing the method as described in any one of claims 1-7.

10. A computer storage medium, characterized in that, The computer storage medium stores a plurality of instructions adapted for loading by a processor and executing the steps of the method as described in any one of claims 1-7.

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