Optical detection apparatus and optical detection method

Abstract

An optical detection apparatus and an optical detection method. The optical detection apparatus comprises: an optical system (10), which is configured to transmit a detection light beam to an object to be tested and receive the detection light beam reflected by said object; a detector (20), which is configured to acquire a target image of said object on the basis of the detection light beam; a reference pattern (30), which is fixed on the optical system (10) and is located in an imaging field of view of the detector (20), wherein the detector (20) is further configured to acquire a reference image of the reference pattern (30); and a data processing module (40), which is configured to compensate for the target image on the basis of the reference image.

Description

Optical detection device and optical detection method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 25, 2023, with application number 202311796161.1, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of optical detection technology, for example, to an optical detection device and an optical detection method. Background Art

[0003] During semiconductor manufacturing, various measurement and inspection equipment is required to monitor and inspect the manufacturing process. However, for most measurement and inspection equipment, the movement of the actuators during the measurement process causes vibrations in the optical system or optical machine, resulting in blurred sample images, affecting the imaging quality of the measurement equipment and reducing the measurement accuracy.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide an optical detection device and an optical detection method to prevent the vibration of the optical system from affecting the image acquisition accuracy and improve the imaging quality of the detection equipment.

[0006] In a first aspect, an embodiment of the present application provides an optical detection device, the optical detection device comprising:

[0007] an optical system configured to transmit a detection beam to the object to be measured and receive the detection beam reflected by the object to be measured;

[0008] a detector, the detector being located on a side of the optical system facing away from the object to be measured, and being configured to obtain a target image of the object to be measured based on the detection light beam;

[0009] a reference pattern fixed to the optical system, wherein the reference pattern is located in the imaging field of the detector, and the detector is further configured to acquire a reference image of the reference pattern;

[0010] The data processing module is connected to the detector and is configured to compensate the target image according to the reference image.

[0011] In some embodiments, the optical detection device further includes a field stop, which is fixed to the optical system. The field stop includes a light-transmitting area and a non-light-transmitting area surrounding the light-transmitting area. The light-transmitting area defines the imaging field of view of the detector.

[0012] The reference pattern is arranged at the edge of the light-transmitting area.

[0013] In some embodiments, the reference pattern is integrated with the field stop, or the reference pattern is fixed to the field stop.

[0014] In some embodiments, there are multiple reference patterns, and the multiple reference patterns are distributed at different edges of the light-transmitting area, or the multiple reference patterns are distributed at the same edge of the light-transmitting area.

[0015] In some embodiments, the field stop is located between the optical system and the detector.

[0016] In some embodiments, the optical detection device further comprises a motion mechanism configured to drive the optical system to move;

[0017] The data processing module is configured to determine motion parameters of the optical system based on a plurality of reference images acquired by the detector during movement of the optical system, and to compensate the target image based on the motion parameters.

[0018] In a second aspect, the embodiments of the present application further provide an optical detection method, which is applicable to the optical detection device provided in the embodiments of the present application. The optical detection method includes:

[0019] Acquire a target image of the object to be measured and a reference image of the reference pattern;

[0020] Compensate the target image based on the reference image.

[0021] In some embodiments, acquiring a target image of the object to be measured and a reference image of a reference pattern includes:

[0022] During the movement of the optical system, a plurality of target images of the object to be measured and a plurality of reference images of the reference pattern are continuously acquired;

[0023] Compensate the target image based on the reference image, including:

[0024] determining motion parameters of the optical system based on the plurality of reference images;

[0025] The target image is compensated according to the motion parameters.

[0026] In some embodiments, determining a motion parameter of an optical system based on a plurality of reference images includes:

[0027] The motion parameter of the optical system is determined according to at least one of the edge blur change of the reference image and the position change of the feature point of the reference image acquired at different moments.

[0028] In some embodiments, compensating the target image according to the reference image includes:

[0029] Acquire an initial reference image corresponding to the reference pattern;

[0030] Compare the reference image with the initial reference image to obtain compensation parameters;

[0031] Compensate the target image according to the compensation parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic structural diagram of an optical detection device provided in an embodiment of the present application;

[0033] FIG2 is a schematic diagram of a partial structure of an optical detection device provided in an embodiment of the present application;

[0034] FIG3 is a schematic diagram of imaging of a reference pattern provided in an embodiment of the present application;

[0035] FIG4 is a flow chart of an optical detection method provided in an embodiment of the present application;

[0036] FIG5 is a flow chart of another optical detection method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] The present application is described below in conjunction with the accompanying drawings and embodiments. The embodiments described herein are used to explain the present application. For ease of description, the accompanying drawings show portions related to the present application.

[0038] The term "including" and its variations used in this application are open-ended, i.e., "including but not limited to." The term "based on" means "based at least in part on." The term "one embodiment" means "at least one embodiment." It should be noted that the concepts of "first" and "second" mentioned in this application are used to distinguish corresponding contents and are not used to limit the order or interdependence.

[0039] FIG1 is a schematic structural diagram of an optical detection device provided in an embodiment of the present application. The optical detection device can be used in semiconductor quantity detection equipment, which can be a wafer defect detection device, a morphology measurement device, etc. Referring to FIG1 , the optical detection device includes: an optical system 10, the optical system 10 is configured to transmit a detection beam to an object to be measured and receive a detection beam reflected by the object to be measured; a detector 20, the detector 20 is located on a side of the optical system 10 away from the object to be measured, and the detector 20 is configured to obtain a target image of the object to be measured based on the detection beam; a reference pattern 30, the reference pattern 30 is fixed to the optical system 10, and the reference pattern 30 is located in the imaging field of the detector 20, and the detector 20 is also configured to obtain a reference image of the reference pattern 30; and a data processing module 40, the data processing module 40 is connected to the detector 20, and the data processing module 40 is configured to compensate the target image based on the reference image.

[0040] For example, as shown in FIG1 , in an embodiment of the present application, the optical detection device includes a light source 50, an optical system 10, a stage 70, a detector 20, a reference pattern 30, and a data processing module 40. The light source 50 is configured to emit a detection beam, which passes through the optical system 10 and is directed toward the object to be measured on the stage 70. The detection beam is reflected by the surface of the object to be measured, and the reflected detection beam re-enters the optical system 10 and is transmitted to the detector 20 via the optical system 10. The optical system 10 may include a variety of optical components, such as lenses with transmissive and reflective functions, imaging objective lenses, etc. The detector 20 generates a target image of the object to be measured based on the received detection beam, and the data processing module 40 processes and analyzes the target image.

[0041] In the process of collecting the image of the object to be measured, the motion mechanism will drive the optical system 10 to move in order to adjust the focal plane of the optical system, etc. When the motion mechanism drives the optical system 10 to move, it may cause the optical system 10 to vibrate. In order to compensate for the influence of the vibration of the optical system 10 on the imaging quality, the embodiment of the present application proposes that a reference pattern 30 can be installed on the optical system 10, and the reference pattern 30 is fixed to the optical system 10 so as to vibrate synchronously with the optical system 10. In addition, the reference pattern 30 is arranged in the imaging field of view of the optical system 10, and the detector 20 can simultaneously generate the target image of the object to be measured and the reference image of the reference pattern 30. It can also be understood that the reference pattern 30 is located in the propagation path of the detection light beam, and the reference pattern 30 blocks part of the detection light beam, and then the detector 20 generates the target image of the object to be measured and the reference image of the reference pattern 30 according to the detection light beam.

[0042] Because the reference pattern 30 vibrates synchronously with the optical system 10, the effect of the vibration of the optical system 10 on the imaging quality of the reference image is the same as the effect of the vibration of the optical system 10 on the imaging quality of the target image. For example, if the vibration of the optical system 10 causes the edges of the target image to be blurred or distorted, the edge blur or distortion of the reference image will be the same as the edge blur or distortion of the target image. Therefore, the data processing module 40 can compensate the target image accordingly based on the changes in the reference image generated by the detector 20, thus providing the optical detection device with image stabilization and improving the acquisition accuracy of the image of the object to be measured.

[0043] The method of compensating the target image using the reference image can be configured by those skilled in the art according to actual needs.

[0044] Optionally, the optical system 10, motion mechanism, and detector can be mounted on a marble frame. Marble has excellent shock absorption properties, effectively isolating the components within the optical detection device (such as the optical system 10, motion mechanism, and detector) from external environmental vibrations. Furthermore, due to the marble's shock absorption properties, vibrations generated by the motion mechanism are not transferred to the detector via the marble frame, ensuring image stabilization.

[0045] FIG1 shows that the light source 50 is located on the left side of the optical system 10 . Those skilled in the art can set the relative position relationship of each component in the optical detection device according to actual conditions.

[0046] The optical detection device provided by the embodiment of the present application includes: an optical system, the optical system is configured to transmit a detection beam to the object to be measured and receive the detection beam reflected by the object to be measured; a detector, the detector is located on the side of the optical system away from the object to be measured, and the detector is configured to obtain a target image of the object to be measured based on the detection beam; a reference pattern, the reference pattern is fixed on the optical system, and the reference pattern is located in the imaging field of view of the detector, and the detector is also configured to obtain a reference image of the reference pattern; a data processing module, the data processing module is connected to the detector, and the data processing module is configured to compensate the target image based on the reference image. Since the reference pattern vibrates synchronously with the optical system, the effect of the optical system vibration on the imaging effect of the reference image is the same as the effect of the optical system vibration on the imaging effect of the target image. The data processing module can compensate the target image accordingly according to the changes in the reference image generated by the detector, correct the target image of the object to be measured, and enable the optical detection device to have an image stabilization function, improve the acquisition accuracy of the image of the object to be measured, improve the imaging quality of the quantity detection equipment, and improve the quantity detection accuracy.

[0047] Optionally, Figure 2 is a partial structural schematic diagram of an optical detection device provided in an embodiment of the present application, which can be combined with reference to Figures 1 and 2. In a possible embodiment, the optical detection device may also include a field of view aperture 60, which is fixed on the optical system 10. The field of view aperture 60 includes a light-transmitting area 601 and a non-light-transmitting area 602 surrounding the light-transmitting area 601. The light-transmitting area 601 defines the imaging field of view of the detector 20; the reference pattern 30 is arranged at the edge of the light-transmitting area 601.

[0048] Figure 2 shows a schematic diagram of the structure of the field of view aperture 60. As shown in Figures 1 and 2, the light-transmitting area 601 of the field of view aperture 60 allows light to pass through, and the non-light-transmitting area 602 at the edge does not allow light to pass through, thereby limiting the range of light that is transmitted through the optical system 10 to the detector 20. The imaging range of the detection light that can pass through the light-transmitting area 601 at the detector 20 can be regarded as the imaging field of view of the detector 20. In this embodiment, the reference pattern 30 is set at the edge of the light-transmitting area 601 and fixed to the non-light-transmitting area 602 of the field of view aperture 60. Generally, the object to be measured is imaged at the center of the field of view. Setting the non-light-transmitting reference pattern 30 at the edge of the light-transmitting area 601 can avoid the reference image from affecting the target image. Figure 3 is a schematic diagram of the imaging of a reference pattern provided in an embodiment of the present application. As shown in Figure 3, the reference image 30' is located at the edge of the imaging field of view 601'.

[0049] 2 , the field stop 60 is located between the optical system 10 and the detector 20. In other embodiments not shown, the field stop 60 may also be disposed between the optical system 10 and the stage 70. Those skilled in the art may adjust the position of the field stop 60 according to actual conditions.

[0050] In some embodiments, the field stop 60 may be a rectangular stop, a fan-shaped stop, or a triangular stop. FIG2 takes a rectangular stop as an example.

[0051] Optionally, the fixing method of the reference pattern 30 and the field stop 60 in the embodiments of the present application can be set according to actual needs. In some embodiments, the reference pattern 30 and the field stop 60 are set integrally, or, in other embodiments, the reference pattern 30 is fixed on the field stop 60.

[0052] The reference pattern 30 and the field stop 60 are integrated together, meaning that during the manufacture of the field stop 60, the reference pattern 30 is fabricated directly on the edge of the light-transmitting region 601 of the field stop 60. The reference pattern 30 is thus a portion of the non-light-transmitting region 602. The reference pattern 30 is fixed to the field stop 60 by attaching a separately fabricated reference pattern 30 to the edge of the field stop 60. The two can be secured together using glue or a fixing assembly (e.g., screws). The integrated design of the reference pattern 30 and the field stop 60 prevents damage to the field stop 60 during installation. Separately manufacturing the reference pattern 30 and subsequently fixing them to the field stop 60 eliminates the need to modify the structure of the field stop 60, allowing the existing field stop 60 to be used.

[0053] The materials of the field stop 60 and the reference pattern 30 can be set by those skilled in the art according to actual needs.

[0054] In some embodiments, referring to FIG. 2 , there are multiple reference patterns 30 , and the multiple reference patterns 30 are distributed at different edges of the light-transmitting area 601 , or the multiple reference patterns 30 are distributed at the same edge of the light-transmitting area 601 .

[0055] Exemplarily, when there is only one reference pattern 30, the target image can be compensated based on the reference image of the reference pattern 30; when there are multiple reference patterns 30, the target image can be compensated in combination with the reference images corresponding to the multiple reference patterns 30 to improve the compensation accuracy.

[0056] When there are multiple reference patterns 30, the multiple reference patterns 30 can be located at different edges or the same edge of the field stop 60. FIG2 shows multiple reference patterns 30 located at the same edge of the light-transmitting region 601 of the field stop 60. Furthermore, the shape, number, and spacing between adjacent reference patterns 30 can be configured according to actual needs.

[0057] In other embodiments, the reference pattern 30 can be directly fixed to the optical components in the optical system 10 without providing the field stop 60 . The fixing method of the reference pattern 30 can be designed according to actual conditions.

[0058] In some embodiments, the data processing module may be configured to: obtain an initial reference image corresponding to the reference pattern, compare the reference image with the initial reference image, obtain compensation parameters, and compensate the target image according to the compensation parameters.

[0059] For example, the initial reference image refers to the image of the reference pattern generated by the detector when the optical system is not vibrating, i.e., the actual image of the reference pattern. For a single image generated by the detector, the data processing module can derive compensation parameters based on the difference between the captured reference image of the reference pattern and the actual initial reference image of the reference pattern. The compensation parameters are then used to correct the target image of the object under test.

[0060] Exemplarily, a compensation parameter may be determined based on at least one of an edge image difference and a feature point position difference between the reference image and the actual reference image, and then the target image of the object to be measured may be corrected according to the compensation parameter.

[0061] Optionally, as described in the above embodiment, the optical detection device further includes a motion mechanism configured to drive the movement of the optical system. The data processing module may also be configured to determine motion parameters of the optical system based on multiple reference images acquired by the detector during movement of the optical system, and to compensate the target image based on the motion parameters.

[0062] The configuration of the motion mechanism can be referenced in related art. During the process of acquiring images of the object to be measured, the detector may capture multiple images continuously. For these images, the data processing module can determine the motion parameters of the optical system based on the changes in the reference image within the multiple images. Motion parameters refer to the vibration and / or motion information of the optical system relative to the object to be measured within the time span of the multiple image captures. Vibration information includes amplitude and frequency, while motion information includes velocity, acceleration, and jerk. Motion parameters can be parameters of the optical system's motion in any direction, such as the horizontal direction.

[0063] Exemplarily, the motion parameters of the optical system may be determined based on at least one of edge blur changes of the reference image acquired at different moments and position changes of feature points of the reference image.

[0064] Edge blur variation refers to the change in the edge blur of a reference image across multiple consecutively captured images, specifically, the change in the edge blur of the reference image over a period of time. The data processing module can determine vibration and / or motion information of the optical system relative to the object under test based on this edge blur variation.

[0065] The change in feature point position refers to the change in the position of feature points in the reference image across multiple consecutively captured images, specifically, the change in the position of feature points in the reference image over a period of time. The data processing module can also determine vibration and / or motion information of the optical system relative to the object under test based on the change in feature point position. The method for selecting feature points can be customized based on actual needs. For example, when the reference pattern is rectangular, the feature points can be the vertices of the rectangle.

[0066] By analyzing at least one of the changes in edge blur and the changes in the positions of feature points in the reference image, the motion parameters of the optical system can be accurately obtained. The captured target image of the object to be measured is processed to remove the influence of the motion parameters, thereby obtaining the actual image of the object to be measured.

[0067] In the embodiments of the present application, determining the motion parameters of the optical system based on at least one of the change in edge blur and the change in the position of feature points in the reference image can be achieved using any relevant technology. For example, the position coordinates of feature points in reference images obtained at two adjacent moments can be compared to determine the displacement of the reference image between those moments. The displacement of the reference image can reflect the displacement of the optical system, and the ratio of the displacement to the time interval is the velocity of the optical system.

[0068] The optical detection device provided in the embodiments of the present application may also include any structure known to those skilled in the art.

[0069] The present application also provides an optical detection method, which is applicable to the optical detection device provided in any embodiment of the present application. The optical detection method can be executed by a data processing module in the optical detection device. FIG4 is a flow chart of an optical detection method provided in an embodiment of the present application. Referring to FIG4, the optical detection method includes the following steps:

[0070] S110 , obtaining a target image of the object to be measured and a reference image of a reference pattern.

[0071] S120: Compensate the target image according to the reference image.

[0072] In the process of collecting the image of the object to be measured, the motion mechanism will drive the optical system to move in order to adjust the focal plane of the optical system, etc. When the motion mechanism drives the optical system to move, it may cause the optical system to vibrate. In order to compensate for the influence of the vibration of the optical system on the imaging quality, the embodiment of the present application proposes that a reference pattern can be installed on the optical system, and the reference pattern is fixed to the optical system so as to vibrate synchronously with the optical system. And the reference pattern is set in the imaging field of view of the optical system, and the detector can simultaneously generate the target image of the object to be measured and the reference image of the reference pattern. It can also be understood that the reference pattern is located in the propagation path of the detection beam, and the reference pattern blocks part of the detection beam, and then the detector generates the target image of the object to be measured and the reference image of the reference pattern according to the detection beam.

[0073] Because the reference pattern vibrates synchronously with the optical system, the effects of optical system vibration on the reference image are the same as those on the target image. Therefore, the data processing module can compensate for the target image based on changes in the reference image generated by the detector, providing the optical inspection device with image stabilization and improving the accuracy of the image acquisition of the object under test.

[0074] Optionally, Figure 5 is a flow chart of another optical detection method provided in an embodiment of the present application. The embodiment shown in Figure 5 is improved on the basis of the above embodiment. S110 in the above embodiment can be: S210, during the movement of the optical system, continuously acquire multiple target images of the object to be measured and multiple reference images of the reference pattern; S120 can be: S221, determine the motion parameters of the optical system based on multiple reference images; S222, compensate the target image according to the motion parameters.

[0075] Referring to FIG5 , the optical detection method includes the following steps:

[0076] S210 , continuously acquiring a plurality of target images of the object to be measured and a plurality of reference images of the reference pattern during the movement of the optical system.

[0077] S221 . Determine motion parameters of the optical system according to a plurality of reference images.

[0078] S222: Compensate the target image according to the motion parameters.

[0079] In the process of acquiring the image of the object to be measured, the detector may capture multiple images continuously. For the multiple images captured continuously, the data processing module can determine the motion parameters of the optical system according to the changes of the reference image in the multiple images, and compensate the target image according to the motion parameters.

[0080] Exemplarily, S221 may be: determining the motion parameters of the optical system according to at least one of edge blur changes of the reference image and position changes of feature points of the reference image acquired at different moments.

[0081] The change in edge blur refers to the change in the degree of edge blur of a reference image across multiple consecutively captured images, that is, the change in the degree of edge blur of the reference image within this time period. The data processing module can determine the vibration information and / or motion information of the optical system relative to the object to be measured based on the change in edge blur. The change in the position of a feature point refers to the change in the position of a feature point of a reference image across multiple consecutively captured images, that is, the change in the position of a feature point of the reference image within this time period. The data processing module can also determine the vibration information and / or motion information of the optical system relative to the object to be measured based on the change in the position of the feature point.

[0082] By analyzing at least one of the changes in edge blur and the changes in the positions of feature points in the reference image, the motion parameters of the optical system can be accurately obtained. The captured target image of the object to be measured is processed to remove the influence of the motion parameters, thereby obtaining the actual image of the object to be measured.

[0083] In some other possible embodiments, S120 may include: acquiring an initial reference image corresponding to the reference pattern; comparing the reference image with the initial reference image to obtain compensation parameters; and compensating the target image according to the compensation parameters.

[0084] The initial reference image is the image of the reference pattern generated by the detector when the optical system is not vibrating. This is also the actual image of the reference pattern. For a single detector image, the data processing module derives compensation parameters based on the difference between the captured reference image of the reference pattern and the actual initial reference image of the reference pattern. This compensation parameter is then used to correct the target image of the object being measured.

[0085] Exemplarily, a compensation parameter may be determined based on at least one of an edge image difference and a feature point position difference between the reference image and the actual reference image, and then the target image of the object to be measured may be corrected according to the compensation parameter.

[0086] The optical detection method provided in the embodiments of the present application includes all technical features and corresponding beneficial effects of the optical detection device provided in any embodiment of the present application. Any content not fully described in the embodiments of the optical detection method can refer to the corresponding embodiments of the optical detection device.

Claims

1. An optical detection device, comprising: An optical system configured to transmit a detection beam to an object to be measured and receive a detection beam reflected by the object to be measured; A detector located on a side of the optical system away from the object to be measured, the detector being configured to obtain a target image of the object to be measured according to the detection beam; A reference pattern fixed on the optical system, and the reference pattern is located in an imaging field of view of the detector, and the detector is further configured to obtain a reference image of the reference pattern; A data processing module connected to the detector, the data processing module being configured to compensate the target image according to the reference image.

2. The optical detection device according to claim 1 further includes a field stop, wherein, The field stop is fixed on the optical system, the field stop includes a light-transmitting area and a non-light-transmitting area surrounding the light-transmitting area, and the light-transmitting area defines the imaging field of view of the detector; The reference pattern is disposed at an edge of the light-transmitting area.

3. The optical detection device according to claim 2, wherein, The reference pattern is integrally provided with the field stop, or the reference pattern is fixed on the field stop.

4. The optical detection device according to claim 3, wherein, The number of the reference patterns is multiple, and the multiple reference patterns are distributed on different edges of the light-transmitting area, or the multiple reference patterns are distributed on the same edge of the light-transmitting area.

5. The optical detection device according to claim 2, wherein, The field stop is located between the optical system and the detector.

6. The optical detection device according to claim 1 further includes a motion mechanism, wherein, The motion mechanism is configured to drive the optical system to move; The data processing module is configured to determine a motion parameter of the optical system according to a plurality of the reference images obtained by the detector during the movement of the optical system, and compensate the target image according to the motion parameter.

7. An optical detection method applicable to the optical detection device according to any one of claims 1 to 6, the optical detection method comprising: Obtaining a target image of an object to be measured and a reference image of a reference pattern; Compensating the target image according to the reference image.

8. The optical detection method according to claim 7, wherein, The obtaining the target image of the object to be measured and the reference image of the reference pattern includes: During the movement of the optical system, continuously obtaining a plurality of the target images of the object to be measured and a plurality of the reference images of the reference pattern; The compensating the target image according to the reference image includes: Determining a motion parameter of the optical system according to a plurality of the reference images; Compensating the target image according to the motion parameter.

9. The optical detection method according to claim 7, wherein, The determining the motion parameter of the optical system according to a plurality of the reference images includes: Determining the motion parameter of the optical system according to at least one of an edge blur change condition of the reference images obtained at different times and a change condition of feature point positions of the reference images.

10. The optical detection method according to claim 7, wherein, The compensating the target image according to the reference image includes: Obtaining an initial reference image corresponding to the reference pattern; Comparing the reference image with the initial reference image to obtain a compensation parameter; Compensating the target image according to the compensation parameter.

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