Automatic focusing method, semiconductor detection method and detection equipment

Abstract

The invention discloses an automatic focusing method, a semiconductor detection method and detection equipment, and the method comprises the steps: obtaining the corresponding motion compensation amount of a scanning position in the optical axis direction of an objective lens, and determining the motion compensation amount based on pre-scanning information representing the surface height distribution of a to-be-detected sample; based on the motion compensation amount of the scanning position, controlling an objective table carrying the to-be-measured sample and an objective lens to move relatively along the optical axis direction so as to perform motion compensation on the distance between the to-be-measured sample and the objective lens along the optical axis direction; and after motion compensation is carried out on the scanning position, focusing is carried out on the to-be-detected sample at the scanning position based on a target focusing algorithm. According to the invention, the problem that the focus following sensitivity is reduced or even defocused due to the large surface height difference of the to-be-detected sample can be solved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor detection, and in particular to an automatic focusing method, a semiconductor detection method and a detection device. Background Art

[0002] In the field of semiconductor inspection, such as semiconductor wafers, inspection equipment has extremely high requirements for accuracy. As the magnification of the objective lens continues to increase and the depth of field gradually decreases, the impact of small changes in the distance between the objective lens and the sample to be tested (such as a wafer) can no longer be ignored. In order to ensure that the sample to be tested is always at the correct working distance, it is necessary to use an autofocus unit and algorithm to measure the distance change between the objective lens and the sample to be tested in real time, quickly and accurately.

[0003] Once the autofocus unit detects the defocus distance of the object, the stage carrying the sample to be tested needs to move quickly to the focal position according to the defocus amount. However, during the movement of the stage, the object is in a defocused state, and the image taken by the inspection equipment will be blurred.

[0004] Therefore, how to focus quickly and accurately when the detection equipment is performing detection is an issue worth studying. Summary of the invention

[0005] In view of the above problems, the present application provides an automatic focusing method, a semiconductor detection method and a detection device, which are described in detail below.

[0006] According to the first aspect, an embodiment provides an automatic focusing method, comprising: Controlling the stage carrying the sample to be tested and the objective lens to move relative to each other along the scanning direction so as to reach a plurality of scanning positions in sequence; Performing motion compensation on some or all of the multiple scanning positions, including: obtaining a motion compensation amount corresponding to the scanning position along the optical axis direction of the objective lens, wherein the motion compensation amount is determined based on pre-scanning information characterizing the surface height distribution of the sample to be measured; based on the motion compensation amount of the scanning position, controlling the relative movement of the stage carrying the sample to be measured and the objective lens along the optical axis direction to perform motion compensation on the distance between the sample to be measured and the objective lens along the optical axis direction; After motion compensation of the scanning position, the sample to be measured is focused at the scanning position based on the target focusing algorithm.

[0007] In one embodiment, the pre-scan information characterizing the surface height distribution of the sample to be tested includes any one of the following: Surface height distribution information of a processed original when it is carried on the stage, wherein the sample to be tested is obtained by processing the processed original; Surface height distribution information of a target sample when it is carried on the stage, wherein the target sample is of the same type as the sample to be tested.

[0008] In one embodiment, the motion compensation amount corresponding to each scanning position in the partial or all scanning positions is pre-stored for retrieval.

[0009] In one embodiment, the scanning position requiring the motion compensation is determined based on the pre-scanning information.

[0010] In one embodiment, the scanning position requiring the motion compensation is determined based on the pre-scanning information, including: For any two adjacent scanning positions, if the pre-scan information indicates that the height difference between the surfaces of the sample to be measured corresponding to the previous scanning position and the next scanning position is greater than the height threshold, the next scanning position needs to perform the motion compensation; otherwise, the next scanning position does not need to perform the motion compensation.

[0011] In one embodiment, the motion compensation amount based on the scanning position controls the relative movement of the stage carrying the sample to be measured and the objective lens along the optical axis direction to perform motion compensation on the distance between the sample to be measured and the objective lens along the optical axis direction, including: In the process that the stage and the objective lens move relative to each other along the scanning direction to reach the scanning position, the stage and the objective lens are synchronously controlled to move relative to each other along the optical axis direction so that the motion compensation is completed for the scanning position when the scanning position is reached; or After the stage and the objective lens move relatively along the scanning direction to reach the scanning position, the stage and the objective lens are controlled to move relatively along the optical axis direction to perform the motion compensation.

[0012] In one embodiment, focusing the sample to be measured based on a target focusing algorithm at the scanning position includes: Real-time acquisition of the distance between the object plane where the sample to be tested is located and the focal plane of the objective lens; The stage and the objective lens are controlled to move relative to each other along the optical axis so that the distance between the object plane and the focal plane is less than a distance threshold.

[0013] In one embodiment, the position of the focal plane in the direction of the optical axis is predetermined, and the position of the focal plane in the direction of the optical axis is compensated for the overfocus plane based on the imaging clear plane.

[0014] According to a second aspect, an embodiment provides a semiconductor detection method, comprising: By using the automatic focusing method as described in any embodiment of the present invention, the automatic focusing of the sample to be tested is sequentially controlled at multiple scanning positions, and the sample to be tested is a semiconductor sample; After automatically focusing the sample to be tested at each scanning position, imaging the sample to be tested is performed to obtain a test image of the test area of ​​the sample to be tested corresponding to the current scanning position; The area to be tested is detected based on the image to be tested.

[0015] According to a third aspect, an embodiment provides a detection device, including: A stage, used for carrying the sample to be tested; An imaging optical path component, comprising a detection sensor and an objective lens; the imaging optical path component is used to perform optical imaging of the sample to be tested carried by the stage through the objective lens, and transmit the optical signal obtained by imaging to the detection sensor, and the detection sensor is used to convert the optical signal into an electrical signal; A driving assembly, used for driving the stage and the objective lens to move relative to each other; A processor is used to execute to implement the method as described in any embodiment of this document.

[0016] According to a fourth aspect, an embodiment provides a computer-readable storage medium, comprising a program, wherein the program can be executed by a processor to implement a method as described in any embodiment herein.

[0017] According to the automatic focusing method, semiconductor detection method, detection equipment and computer-readable storage medium of the above-mentioned embodiments, relevant information that can characterize the height facets of the surface of the sample to be tested is obtained in advance, and based on the relevant information, motion compensation of the focusing distance of the sample to be tested is performed during the actual detection or scanning process, so that the distance between the object plane of the sample to be tested and the focal plane of the objective lens is controlled within a preset range, thereby overcoming the problem of decreased focus sensitivity or even defocusing due to the large height difference on the surface of the sample to be tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a detection device according to an embodiment; Figure 2 is a flow chart of an automatic focusing method according to an embodiment; Figure 3 A flowchart of performing motion compensation for a scanning position in one embodiment; Figure 4 A flowchart of focusing a sample to be measured based on a target focusing algorithm at a scanning position in an embodiment; Figure 5 The present invention is a flow chart of a semiconductor detection method according to an embodiment. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0020] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0021] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0022] When the testing equipment is testing, how to focus quickly and accurately is a problem worth studying. Let's take the wafer as an example. With the continuous advancement of semiconductor technology, the graphic structure of the wafer has become more and more complex, especially for wafers with more step structures such as 3D NAND wafers (three-dimensional flash memory wafers). The testing equipment needs to continuously follow the step structure on its surface at a high frequency and a large extent, which makes it very easy to produce out-of-focus blur when taking pictures during the focus following process. In addition, some wafers have special areas with significant height differences. For example, there is a large height difference between the cutting road and the graphic area, and in some scenes, when the stage carries the sample to be tested by means such as clamping, the wafer warping is more serious and cannot be ignored; therefore, when the height difference between adjacent areas of the wafer surface is far beyond the focal depth range of the testing equipment, due to the limitation of the stage response, the object surface cannot be moved to the focal plane in time, resulting in out-of-focus blur in the picture, which in turn causes false detection.

[0023] In order to solve the problem that the large height difference of the surface of the sample to be tested leads to slow focus response or even failure to focus successfully, thus causing blurred imaging, the applicant proposes: pre-acquire relevant information that can characterize the height facets of the surface of the sample to be tested, and based on the relevant information, perform motion compensation for the focusing distance of the sample to be tested during the actual detection or scanning process, so that the distance between the object plane of the sample to be tested and the focal plane of the objective lens is controlled within a preset range, thereby overcoming the problem that the large height difference of the surface of the sample to be tested easily leads to decreased focus sensitivity or even defocusing. The following is a detailed description.

[0024] Please refer to Figure 1 In some embodiments, a detection device 100 is provided, and the detection device 100 is used to scan the sample to be tested and form an image to detect the sample to be tested; in some embodiments, the detection device 100 includes a stage 10, an imaging optical path component 20, a driving component 30 and a processor 40, wherein the imaging optical path component 20 includes a detection sensor 21 and an objective lens 22; the following is a detailed description.

[0025] In some embodiments, the stage 10 is used to carry the sample 01 to be tested.

[0026] In some embodiments, the stage 10 is movable, and the movement of the stage 10 can drive the sample 01 to be tested thereon to move.

[0027] In some examples, the stage 10 can move along the scanning direction, thereby driving the carried sample 01 to move along the scanning direction, so that the detection device 100 can scan the entire surface of the sample 01. In some examples, the scanning direction can be the X-axis direction, the Y-axis direction, or the plane direction defined by the X-axis and the Y-axis (for example, the horizontal direction or the horizontal plane direction).

[0028] In some embodiments, the stage 10 can move along the optical axis of the objective lens 22, thereby driving the carried sample 01 to move along the optical axis of the objective lens 22. In some examples, the optical axis of the objective lens 22 can be the Z axis direction (eg, vertical direction).

[0029] Therefore, in some embodiments, the stage 10 can move along the Z-axis direction (eg, vertical direction), thereby driving the carried sample 01 to move along the Z-axis direction (eg, vertical direction).

[0030] It should be noted that the sample to be tested 01 in this article can be a semiconductor product such as a wafer or a chip. Since there may be defects such as flaws on its surface, it is necessary to perform optical inspection on its surface in order to control the quality of the product.

[0031] In some embodiments, the imaging optical path component 20 is used to image the sample 01 to be tested carried by the stage 10. In some specific embodiments, the imaging optical path component 20 is used to perform optical imaging on the sample 01 to be tested carried by the stage 10 through the objective lens 22, and transmit the optical signal obtained by imaging to the detection sensor 21, and the detection sensor 21 is used to convert the optical signal into an electrical signal.

[0032] It can be understood that the imaging optical path component 20 may include other components in addition to the detection sensor 21 and the objective lens 22, such as other optical devices arranged in the optical path between the detection sensor 21 and the objective lens 22, such as a collimating lens or even a filter, a spectrometer, etc.; in addition, the imaging optical path component 20 may also include a light source, and the illumination light emitted by the light source is projected onto the sample 01 to be tested carried by the stage 10 after passing through the objective lens 22, and the light formed by the surface reflection and scattering of the sample 01 to be tested is collected by the objective lens 22 and then incident on the detection sensor 21. The light source may be any one of LED, xenon lamp, mercury lamp, halogen lamp, laser lamp, laser plasma lamp, and laser-driven white light source lamp, so the illumination light may be white light, colored light or laser.

[0033] In some embodiments, the driving assembly 30 is used to drive the stage 10 and the objective lens 22 to move relative to each other. In specific implementation, the driving assembly 30 may drive the stage 10 to move while the objective lens 22 remains stationary, or the driving assembly 30 may drive the objective lens 22 to move while the stage 10 remains stationary, or the driving assembly 30 may drive the stage 10 to move and drive the objective lens 22 to move.

[0034] For example, the driving component 30 drives the stage 10 and the objective lens 22 to move relative to each other along the scanning direction. The driving component 30 may drive the stage 10 to move along the scanning direction while the objective lens 22 remains stationary. The driving component 30 may drive the objective lens 22 to move along the scanning direction while the stage 10 remains stationary. The driving component 30 may also drive the stage 10 to move and drive the objective lens 22 to move so as to achieve relative movement of the two along the scanning direction.

[0035] For another example, the drive component 30 drives the stage 10 and the objective lens 22 to move relative to each other along the optical axis direction of the objective lens 22. The drive component 30 may drive the stage 10 to move along the optical axis direction while the objective lens 22 remains stationary. The drive component 30 may drive the objective lens 22 to move along the optical axis direction while the stage 10 remains stationary. The drive component 30 may also drive the stage 10 to move and drive the objective lens 22 to move so as to achieve relative movement of the two along the optical axis direction.

[0036] Therefore, the driving component 30 drives the objective lens 22 to move relative to each other along the Z-axis direction (e.g., the vertical direction). The driving component 30 may drive the objective lens 22 to move along the Z-axis direction (e.g., the vertical direction) while the objective lens 22 remains stationary. The driving component 30 may drive the objective lens 22 to move along the Z-axis direction (e.g., the vertical direction) while the stage 10 remains stationary. The driving component 30 may also drive the stage 10 to move and drive the objective lens 22 to move so as to achieve relative movement of the two along the Z-axis direction (e.g., the vertical direction).

[0037] The driving assembly 30 can be implemented based on driving components such as piezoelectric, servo motor, DD motor, etc.

[0038] In some embodiments, the processor 40 includes but is not limited to a central processing unit (CPU), a micro controller unit (MCU), a field-programmable gate array (FPGA), a digital signal processing (DSP), and other devices for interpreting computer instructions and processing data in computer software.

[0039] In some embodiments, the processor 40 is capable of executing each computer application in the non-transitory computer-readable storage medium, thereby executing the corresponding steps and methods. For example, the processor 40 can be implemented by software, hardware, firmware, or a combination thereof, and can use a circuit, a single or multiple application-specific integrated circuits (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a central processing unit (CPU), a controller, a microcontroller, a microprocessor, at least one of which can enable the processor 40 to execute some or all steps of the autofocus method in various embodiments of the present application, or any combination of the steps, or so that the processor 40 can execute some or all steps of the semiconductor detection method in various embodiments of the present application, or any combination of the steps.

[0040] The above is some description of the detection device 100.

[0041] Please refer to Figure 2 Some embodiments disclose an automatic focusing method 101; in some examples, the automatic focusing method 101 of the present application can be applied to the detection device 100 disclosed herein, for example, the processor 40 in the detection device 100 can execute some steps or all steps of the automatic focusing method 101 or any combination of the steps; in some embodiments, the automatic focusing method 101 includes the following steps: Step 110: Control the stage 10 carrying the sample 01 to be tested and the objective lens 22 to move relative to each other along the scanning direction to sequentially reach a plurality of scanning positions.

[0042] In step 110 , the stage 10 carrying the sample 01 to be tested and the objective lens 22 are controlled to move relative to each other along the scanning direction. The stage 10 and the objective lens 22 may move together, or one of them may move while the other remains stationary.

[0043] In some examples, the scanning direction may be an X-axis direction, a Y-axis direction, or a plane direction defined by the X-axis and the Y-axis (eg, a horizontal direction or a horizontal plane direction).

[0044] Therefore, in one example, the objective lens 22 may remain stationary in the scanning direction, while the stage 10 carrying the sample to be tested 01 moves along the scanning direction (e.g., horizontal / horizontal plane direction) to sequentially reach multiple scanning positions. In this way, the detection device 100 can scan the entire surface of the sample to be tested 01.

[0045] It can be understood that the scanning position is a position defined by the scanning direction, which is a position relative to the scanning direction. Taking the scanning direction as the horizontal plane as an example, the scanning position is a position defined by the X-axis and the Y-axis, and the coordinate in the Z-axis direction has no effect. For example, (x1, y1, z1) and (x1, y1, z2) refer to the same scanning position. At the same scanning position, the coordinate in the Z-axis direction will affect the focusing effect, which is further explained below.

[0046] Step 120: Perform motion compensation on part or all of the multiple scanning positions.

[0047] In some examples, the motion compensation refers to motion compensation in a direction perpendicular to the scanning direction, such as motion compensation along the optical axis direction of the objective lens 22 , the Z-axis direction, or the vertical direction.

[0048] By performing motion compensation on the scanning position in step 120, it is possible to overcome the problem that the focus sensitivity is reduced or even defocused due to the large height difference on the surface of the sample to be measured, which is explained in detail below.

[0049] Please refer to Figure 3In some embodiments, step 120 of performing motion compensation on some or all of the plurality of scanning positions comprises the following steps: Step 121: Obtain the motion compensation amount corresponding to the scanning position along the focusing direction. In some embodiments, the focusing direction is perpendicular to the scanning direction, for example, along the optical axis direction of the objective lens 22, the Z-axis direction or the vertical direction.

[0050] The motion compensation amount of the scanning position may be a relative motion amount in the above-mentioned focusing direction. For example, for any scanning position, its motion compensation amount may be the motion amount or distance between the scanning position and its previous scanning position in the above-mentioned focusing direction. For example, the previous scanning position is (x1, y1, z1), and the next scanning position is (x2, y2, z1+d), wherein at least one of x1 and x2, y1 and y2 is different; (x1, y1, z1) may be the coordinate position of the previous scanning position before focusing based on the target focusing algorithm described below. It can also be the coordinate position after focusing based on the target focusing algorithm below, and (x2, y2, z1+d) is the coordinate position of the next scanning position before focusing based on the target focusing algorithm below. It can be seen that in the scanning direction, it moves from the previous scanning position (x1, y1) to the next scanning position (x2, y2), and in the Z-axis direction, it changes from z1 to z1+d, d is the motion compensation amount of the scanning position (x2, y2). It can be understood that d can be a positive number or a negative number. If it is a positive number, it means upward movement, and if it is a negative number, it means downward movement.

[0051] The motion compensation amount of the scanning position can also be an absolute motion amount in the above-mentioned focusing direction. For example, the previous scanning position is (x1, y1, z1), and the next scanning position is (x2, y2, z2), among which, at least one of x1 and x2, y1 and y2 is different; (x1, y1, z1) is the coordinate position of the previous scanning position before focusing based on the target focusing algorithm below, and (x2, y2, z2) is the coordinate position of the next scanning position before focusing based on the target focusing algorithm below. It can be seen that in the scanning direction, it moves from the previous scanning position (x1, y1) to the next scanning position (x2, y2), and in the Z-axis direction, it moves to z2. z2 is the motion compensation amount of the scanning position (x2, y2), which is a quantity relative to the origin of the Z-axis coordinate.

[0052] In some embodiments, the amount of motion compensation is determined based on pre-scan information characterizing the height distribution of the surface of the sample to be measured.

[0053] In some examples, the pre-scan information characterizing the surface height distribution of the sample to be tested includes: surface height distribution information when the processed original is carried on the stage 10, wherein the sample to be tested 01 is processed by the processed original. For example, if the sample to be tested 01 is a semiconductor product such as a wafer or a chip, the processed original can be a bare silicon wafer; due to factors such as slight bending of the structure of the stage 10 itself and structural deformation caused by temperature changes, the surface height difference of the sample to be tested 01 will be caused, and this height difference is actually the plane warping information of the stage 10.

[0054] In some examples, the pre-scan information characterizing the surface height distribution of the sample to be tested includes: surface height distribution information of the target sample when it is carried on the stage 10, wherein the target sample is of the same category as the sample to be tested 01. The same category may mean that from a product perspective, the product models are the same. In the actual detection or scanning process, the first sample to be tested 01 of the same batch of products can be used as the target sample.

[0055] Using the surface height distribution information of the target sample when it is carried on the stage 10 as a pre-scan signal to characterize the surface height distribution of the sample to be tested is more accurate and can better characterize the surface height distribution of the sample to be tested than using the surface height distribution information of the processed original when it is carried on the stage 10 as a pre-scan signal to characterize the surface height distribution of the sample to be tested.

[0056] The pre-scan information can be obtained in advance before scanning or testing the sample to be tested 01. For example, after placing the corresponding object (such as the processed original or target sample mentioned above) on the stage 10, an additional altimeter or the height measurement function of the detection equipment 100 itself (if any) is used to mark the points and record the Z-axis height of the above-mentioned object at each scanning position defined by the horizontal X-axis and / or Y-axis, thereby obtaining pre-scan information characterizing the height distribution of the surface of the sample to be tested.

[0057] In some embodiments, the corresponding motion compensation amount of each scanning position that needs motion compensation is pre-stored for retrieval. Therefore, after scanning or testing the sample 01 to be tested, before automatically focusing on a certain scanning position, the motion compensation amount corresponding to the scanning position is obtained to perform motion compensation on the scanning position in the focusing direction.

[0058] In some embodiments, all scan positions need to be motion compensated.

[0059] In some embodiments, some scanning positions require motion compensation, while the remaining scanning positions do not require motion compensation.

[0060] In some embodiments, the scanning position that needs to perform the motion compensation is determined based on the pre-scan information. For example, for any two adjacent scanning positions, if the pre-scan information indicates that the height difference between the surface of the sample to be tested corresponding to the previous scanning position and the next scanning position is greater than the height threshold, then the next scanning position needs to perform motion compensation, otherwise, the next scanning position does not need to perform the motion compensation. It should be noted that two scanning positions are adjacent in time sequence. For example, if the previous scanning position is reached first and then the next scanning position is reached, these two scanning positions are adjacent scanning positions.

[0061] Step 123: Based on the motion compensation amount of the scanning position, the scanning position is motion compensated in the focusing direction. For example, in step 123, based on the motion compensation amount of the scanning position, the stage 10 carrying the sample 01 to be tested and the objective lens 22 are controlled to move relative to each other along the above-mentioned focusing direction to perform motion compensation on the distance between the sample 01 to be tested and the objective lens 22 along the above-mentioned focusing direction.

[0062] When performing motion compensation on the scanning position in step 123, motion compensation in the focus direction may be performed simultaneously in the process of reaching the scanning position along the scanning direction, or may be performed after reaching the scanning position.

[0063] In some examples, during the process of relative movement of the stage 10 and the objective lens 22 along the scanning direction to reach the scanning position A, step 123 synchronously controls the relative movement of the stage 10 and the objective lens 22 along the focusing direction so that when the scanning position A is reached, the motion compensation for the scanning position A has been completed. For example, after the scanning position previous to the scanning position A is scanned, the stage 10 and the objective lens 22 will continue to move relative to each other along the scanning direction so as to reach the scanning position A from the previous scanning position. During this process, the stage 10 and the objective lens 22 move relative to each other along the focusing direction so that when the scanning position A is reached, the motion compensation for the scanning position A has been completed.

[0064] In some examples, after the stage 10 and the objective lens 22 move relative to each other along the scanning direction to reach the scanning position A, step 123 controls the stage 10 and the objective lens 22 to move relative to each other along the focusing direction to perform motion compensation for the scanning position A.

[0065] Step 130: After performing motion compensation on the scanning position, focusing the sample to be measured is performed at the scanning position based on a target focusing algorithm.

[0066] In addition, in some examples where some scanning positions require motion compensation and some scanning positions do not require motion compensation, step 130 also includes: for the scanning positions that do not require motion compensation, after reaching such scanning positions, the sample to be measured can also be focused based on the target focusing algorithm.

[0067] The target focusing algorithm may adopt an existing focusing algorithm or a focusing algorithm to be developed in the future.

[0068] Please refer to Figure 4 In some embodiments, step 130 of focusing the sample to be tested at the scanning position based on the target focusing algorithm may include: Step 131: Acquire the distance between the object plane where the sample 01 to be tested is located and the focal plane of the objective lens 22 in real time.

[0069] Step 133: Control the relative movement of the stage 10 and the objective lens 22 along the focusing direction so that the distance between the object plane and the focal plane is less than a distance threshold, for example, so that the object plane is within the depth of field range.

[0070] In some embodiments, the position of the focal plane of the objective lens 22 in the focusing direction is predetermined, and the position of the focal plane in the focusing direction is compensated for the over-focus plane based on the imaging clear plane.

[0071] Taking the focusing direction as the Z-axis direction as an example, the detection device 100 can traverse the Z-axis of the stage 10 to determine the position of the focal plane of the objective lens 22 on the Z-axis, which may be recorded as Z-fp, and then obtain the focal plane compensation value based on the coordinate difference between the focal plane of the objective lens 22 and the imaging clear surface on the Z-axis; wherein the imaging clear surface can be observed and determined by the human eye, or the imaging clear surface can be determined using a clarity algorithm; the focal plane compensation is performed on the position of the focal plane in the focusing direction, that is, the Z-axis direction according to the focal plane compensation value. For example, the detection device 100 adjusts the internal optical device so that the position of the focal plane of the objective lens 22 on the Z-axis coincides with the position of the imaging clear surface on the Z-axis. For another example, although the position of the focal plane on the Z-axis is Z-fp, when the target focusing algorithm involves the position of the focal plane on the Z-axis, the position of the focal plane on the Z-axis is corrected within the algorithm through the focal plane compensation value.

[0072] After the focusing is successfully performed in step 130, the detection device 100 can take pictures to obtain an image corresponding to the current scanning position. Based on the taken image, the detection device 100 can detect whether there is a defect in the area corresponding to the current scanning position of the sample 01 to be tested.

[0073] The automatic focusing method 101 of the present invention can overcome the problem that the large height difference on the surface of the sample to be measured easily leads to a decrease in the focus sensitivity or even defocusing.

[0074] In addition, in the automatic focusing method 101 of this article, after the focusing is successfully performed in step 130, the detection device 100 can take pictures to obtain an image corresponding to the current scanning position. Based on the taken image, the detection device 100 can detect whether there are defects in the area corresponding to the current scanning position of the sample 01 to be tested.

[0075] Therefore, please refer to Figure 5 Some embodiments further disclose a semiconductor detection method 201; in some examples, the semiconductor detection method 201 of the present application can be applied to the detection device 100 disclosed herein, for example, the processor 40 in the detection device 100 can execute some steps or all steps of the semiconductor detection method 201 or any combination of the steps; in some embodiments, the semiconductor detection method 201 includes the following steps: Step 210: sequentially controlling automatic focusing of the sample 01 to be tested at multiple scanning positions; wherein the sample 01 to be tested is a semiconductor sample, for example, the sample 01 to be tested can be a semiconductor sample or product such as a wafer or a chip.

[0076] In some embodiments, the automatic focusing method 101 of any embodiment of the present invention can be used to implement step 210 of sequentially controlling automatic focusing of the sample 01 to be tested at multiple scanning positions; for example, the stage 10 and the objective lens 22 carrying the sample 01 to be tested are controlled to move relative to each other along the scanning direction to reach multiple scanning positions in sequence, motion compensation is performed on part or all of the multiple scanning positions, and after motion compensation is performed on the scanning positions, the sample 01 to be tested is focused or automatically focused at the scanning positions based on the target focusing algorithm.

[0077] Step 220: After automatically focusing the sample 01 at each scanning position, imaging the sample 01 is performed to obtain an image of the sample 01 at the test area corresponding to the current scanning position.

[0078] It can be understood that the sample to be tested 01 corresponds to different test areas at different scanning positions, and the scanning and imaging of the surface of the sample to be tested 01 can be completed by imaging the different test areas of the sample to be tested 01 at multiple different scanning positions.

[0079] Step 230: perform detection, such as defect detection, on the test area of ​​the test sample 01 based on the test image. It can be understood that step 230 can be based on existing or future detection algorithms to perform detection of the corresponding test area based on the test image.

[0080] This document is described with reference to various exemplary embodiments. However, those skilled in the art will recognize that changes and modifications may be made to the exemplary embodiments without departing from the scope of this document. For example, various operating steps and components for performing the operating steps may be implemented in different ways (e.g., one or more steps may be deleted, modified, or combined into other steps) depending on the specific application or considering any number of cost functions associated with the operation of the system.

[0081] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. In addition, as understood by those skilled in the art, the principles of this article can be reflected in a computer program product on a computer-readable storage medium, which is pre-installed with a computer-readable program code. Any tangible, non-temporary computer-readable storage medium can be used, including magnetic storage devices (hard disks, floppy disks, etc.), optical storage devices (CD to ROM, DVD, Blue Ray disks, etc.), flash memory and / or the like. These computer program instructions can be loaded onto a general-purpose computer, a special-purpose computer, or other programmable data processing device to form a machine, so that these instructions executed on a computer or other programmable data processing device can generate a device that implements a specified function. These computer program instructions can also be stored in a computer-readable memory, which can instruct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory can form a manufactured product, including an implementation device that implements a specified function. Computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operating steps are performed on a computer or other programmable device to generate a computer-implemented process, so that the instructions executed on a computer or other programmable device can provide steps for implementing a specified function.

[0082] Although the principles of this invention have been shown in various embodiments, many modifications of structures, arrangements, proportions, elements, materials and components particularly suitable for specific environments and operational requirements can be used without departing from the principles and scope of this invention. The above modifications and other changes or amendments will be included in the scope of this invention.

[0083] The foregoing specific description has been described with reference to various embodiments. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of the present disclosure. Therefore, the consideration of the present disclosure will be illustrative rather than restrictive, and all these modifications will be included in its scope. Similarly, the advantages, other advantages and solutions to the problems of various embodiments have been described above. However, the benefits, advantages, solutions to the problems and any elements that can produce these, or make them more clear, should not be interpreted as critical, necessary or necessary. The term "include" and any other variants used in this article are all non-exclusive inclusions, so that the process, method, article or device including the list of elements not only includes these elements, but also includes other elements that are not explicitly listed or do not belong to the process, method, system, article or device. In addition, the term "coupled" and any other variants used in this article refer to physical connections, electrical connections, magnetic connections, optical connections, communication connections, functional connections and / or any other connections.

[0084] Those skilled in the art will appreciate that many changes may be made to the details of the above-described embodiments without departing from the basic principles of the invention. Therefore, the scope of the present invention should be determined solely by the claims.

Claims

1. An automatic focusing method, characterized in that: include: Controlling the stage carrying the sample to be tested and the objective lens to move relative to each other along the scanning direction so as to reach a plurality of scanning positions in sequence; Performing motion compensation on some or all of the multiple scanning positions, including: obtaining a motion compensation amount corresponding to the scanning position along the optical axis direction of the objective lens, wherein the motion compensation amount is determined based on pre-scanning information characterizing the surface height distribution of the sample to be measured; based on the motion compensation amount of the scanning position, controlling the relative movement of the stage carrying the sample to be measured and the objective lens along the optical axis direction to perform motion compensation on the distance between the sample to be measured and the objective lens along the optical axis direction; After motion compensation of the scanning position, the sample to be measured is focused at the scanning position based on the target focusing algorithm.

2. The automatic focusing method according to claim 1, wherein: The pre-scan information characterizing the surface height distribution of the sample to be tested includes any one of the following: Surface height distribution information of a processed original when it is carried on the stage, wherein the sample to be tested is obtained by processing the processed original; Surface height distribution information of a target sample when it is carried on the stage, wherein the target sample is of the same type as the sample to be tested.

3. The automatic focusing method according to claim 1, wherein: The motion compensation amount corresponding to each scanning position in the partial or all scanning positions is pre-stored for recall.

4. The automatic focusing method according to any one of claims 1 to 3, characterized in that: The scanning position where the motion compensation needs to be performed is determined based on the pre-scanning information.

5. The automatic focusing method according to claim 4, characterized in that: The scanning position requiring the motion compensation is determined based on the pre-scanning information, including: For any two adjacent scanning positions, if the pre-scan information indicates that the height difference between the surfaces of the sample to be measured corresponding to the previous scanning position and the next scanning position is greater than the height threshold, the next scanning position needs to perform the motion compensation; otherwise, the next scanning position does not need to perform the motion compensation.

6. The automatic focusing method according to claim 1, wherein: The motion compensation amount based on the scanning position controls the relative movement of the stage carrying the sample to be measured and the objective lens along the optical axis direction to perform motion compensation on the distance between the sample to be measured and the objective lens along the optical axis direction, including: In the process that the stage and the objective lens move relative to each other along the scanning direction to reach the scanning position, the stage and the objective lens are synchronously controlled to move relative to each other along the optical axis direction so that the motion compensation is completed for the scanning position when the scanning position is reached; or After the stage and the objective lens move relatively along the scanning direction to reach the scanning position, the stage and the objective lens are controlled to move relatively along the optical axis direction to perform the motion compensation.

7. The automatic focusing method according to claim 1, wherein: The focusing of the sample to be measured based on the target focusing algorithm at the scanning position includes: Real-time acquisition of the distance between the object plane where the sample to be tested is located and the focal plane of the objective lens; The stage and the objective lens are controlled to move relative to each other along the optical axis so that the distance between the object plane and the focal plane is less than a distance threshold.

8. The automatic focusing method according to claim 7, wherein: The position of the focal plane in the direction of the optical axis is predetermined, and the position of the focal plane in the direction of the optical axis is compensated for the overfocus plane based on the imaging clear plane.

9. A semiconductor detection method, characterized in that: include: According to the method according to any one of claims 1 to 8, automatically focusing the sample to be tested at multiple scanning positions is controlled in sequence, and the sample to be tested is a semiconductor sample; After automatically focusing the sample to be tested at each scanning position, imaging the sample to be tested is performed to obtain a test image of the test area of ​​the sample to be tested corresponding to the current scanning position; The area to be tested is detected based on the image to be tested.

10. A detection device, characterized in that: include: A stage, used for carrying the sample to be tested; Imaging optical path components, including detection sensors and objective lenses; The imaging optical path component is used to perform optical imaging of the sample to be tested carried by the stage through the objective lens, and transmit the optical signal obtained by imaging to the detection sensor, and the detection sensor is used to convert the optical signal into an electrical signal; A driving assembly, used for driving the stage and the objective lens to move relative to each other; A processor, configured to execute the method according to any one of claims 1 to 9.

11. A computer-readable storage medium, characterized in that: The method comprises a program which can be executed by a processor to implement the method according to any one of claims 1 to 9.

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