Dark-field wafer inspection equipment, its optical calibration system and optical calibration method

Abstract

The present application discloses a dark-field wafer detection device, its optical calibration system and optical calibration method, which relates to the technical field of wafer detection devices. A pupil is provided on the light-emitting side of the imaging system, and the pupil is located on the pupil plane of the imaging system. The calibration detection module can obtain a calibration image based on the pupil plane and can perform imaging according to the detection light after passing through the scattering field. In the present application, at the position of the pupil plane of the imaging system, the scattered light will undergo spatial separation. The calibration detection module can image the system pupil plane, and then can obtain the intensity distribution map of the pupil plane. The present application can control the polarization analysis conditions through the polarization analysis module. Based on the obtained calibration image, the polarization transmittance of the illumination light path to be measured relative to the scattering field can be accurately measured and calibrated.

Description

Technical Field

[0001] The present application relates to the technical field of wafer inspection equipment, and in particular to a dark-field wafer inspection equipment, its optical calibration system and optical calibration method. Background Art

[0002] A dark-field wafer inspection equipment is a key equipment for defect inspection of wafers during the semiconductor manufacturing process. The main working principle of the dark-field wafer inspection equipment is: the illumination system emits light to irradiate the surface of the wafer, the imaging system collects the light scattered by the wafer surface and sends it to the detection camera for imaging, and defects in the wafer can be identified based on the image obtained by the detection camera.

[0003] The illumination system and the imaging system are important components of the dark-field wafer inspection equipment. During the actual inspection process, when facing different types of defects or wafer materials, it is first necessary to configure and switch the polarization state conditions of the illumination system relative to the object surface to be measured. After the illumination beam carrying polarization information is scattered by the object surface to be measured, it is processed by the imaging system and enters the detection camera for signal acquisition and analysis. In order to correspond this polarization information with the detection result, it is necessary to design an optical calibration system and an optical calibration method that can determine the polarization transmittance after passing through the scattering field. Summary of the Invention

[0004] In view of the above problems, the present application provides a dark-field wafer inspection equipment, its optical calibration system and optical calibration method to achieve the purpose of being able to determine the polarization transmittance after passing through the scattering field. The specific solutions are as follows:

[0005] In the first aspect of the present application, an optical calibration system is provided. The optical calibration system is used for a dark-field wafer inspection equipment, and the optical calibration system includes:

[0006] An illumination system for providing an initial illumination beam;

[0007] A polarization module for applying polarization modulation to the initial illumination beam to form a polarized illumination beam;

[0008] An imaging system for collecting the polarized illumination beam after being scattered by the target to form a detection light;

[0009] An analyzer module for performing polarization screening on the detection light;

[0010] A pupil located on the light output side of the analyzer module and on the pupil plane of the imaging system;

[0011] A calibration detection module for collecting the detection light passing through the pupil to form a calibration image; the calibration image can at least characterize the polarization transmittance of the polarized illumination beam after being scattered.

[0012] Optionally, in the above optical calibration system, the dark-field wafer inspection device has a wafer inspection mode and a polarization transmittance calibration mode;

[0013] The calibration detection module includes: an in-cut mirror, a pupil imaging mirror, and a first camera; wherein, the in-cut mirror is movably placed in the optical calibration system; the in-cut mirror is used to be placed on the light-emitting side of the pupil in the polarization transmittance calibration mode to reflect the detection light passing through the pupil to the pupil imaging mirror; the pupil imaging mirror is used to image the collected detection light to the target surface position of the first camera; the first camera is used to form a calibration image based on the incident detection light;

[0014] Wherein, in the wafer inspection mode, the target is the wafer to be inspected, and the in-cut mirror is used to be placed outside the irradiation area of the light emitted from the pupil, so that the detection light passing through the pupil can be incident on the wafer inspection module coaxial with the imaging system, and the wafer inspection module is used to form a defect detection image capable of characterizing the defect information of the wafer to be inspected based on the detection light.

[0015] Optionally, in the above optical calibration system, the in-cut mirror is installed on a movable member;

[0016] Wherein, the movable member can drive the in-cut mirror to move horizontally or rotate; the movable member is used to drive the in-cut mirror to be placed on the light-emitting side of the pupil, or drive the in-cut mirror to be placed outside the irradiation area of the light emitted from the pupil.

[0017] Optionally, in the above optical calibration system, it further includes a host computer connected to the calibration detection module, and the host computer is used to determine the polarization transmittance based on the calibration image.

[0018] Optionally, in the above optical calibration system, the host computer is used to determine the polarization transmittance corresponding to the overall area of the calibration image based on the overall gray data of the calibration image;

[0019] And / or, the host computer is used to divide the calibration image into multiple sub-regions, and determine the polarization transmittance corresponding to the sub-regions based on the gray data of the sub-regions.

[0020] The second aspect of the present application provides an optical calibration method for the above optical calibration system, including:

[0021] After calibrating the polarization state of the polarizing module, turn on the illumination system, and emit an initial illumination beam through the illumination system; wherein, the initial illumination beam forms a polarized illumination beam obliquely incident on the target after being subjected to polarization modulation by the polarizing module, and the target is a standard sheet with a set roughness; the polarized illumination beam after being scattered by the standard sheet forms detection light through the imaging system; the detection light passes through the pupil and is incident on the calibration detection module;

[0022] After forming a polarized illumination beam with a target polarization state through a polarizing module, the polarization state of the analyzer module is adjusted to match the target polarization state;

[0023] Obtain a calibration image corresponding to the target polarization state through a calibration detection module; the calibration image can at least characterize the polarization transmittance after the polarized illumination beam passes through scattering.

[0024] Optionally, in the above optical calibration method, the optical calibration system is used for a dark-field wafer inspection device, and the dark-field wafer inspection device has a wafer inspection mode and a polarization transmittance calibration mode;

[0025] The calibration detection module includes: an in-cut mirror, a pupil imaging mirror, and a first camera; the in-cut mirror is movably placed in the optical calibration system;

[0026] In the polarization transmittance calibration mode, place the in-cut mirror on the light output side of the pupil to reflect the detection light passing through the pupil to the pupil imaging mirror, image the collected detection light to the target surface position of the first camera through the pupil imaging mirror, and collect the detection light through the first camera to form a calibration image;

[0027] In the wafer inspection mode, place the in-cut mirror outside the illumination area of the light rays exiting the pupil, so that the detection light passing through the pupil can be incident on a wafer inspection module coaxial with the imaging system, and the wafer inspection module is used to form a defect detection image that can characterize the defect information of the wafer to be inspected based on the detection light.

[0028] Optionally, in the above optical calibration method, the method for calibrating the polarization state of the polarizing module includes:

[0029] After adjusting the analyzer module to a non-analyzing state, collect a background image under the condition of no initial illumination beam through the calibration detection module;

[0030] After turning on the illumination system, rotate the polarizing module to find the first polarization position, the second polarization position, and the third polarization position of the polarizing module; at the first polarization position, the first camera in the calibration detection module has the maximum photosensitive intensity, and the polarized illumination beam has P polarization; at the second polarization position, the first camera has the minimum photosensitive intensity, and the polarized illumination beam has S polarization; at the third polarization position, the photosensitive intensity of the first camera is between the maximum photosensitive intensity and the minimum photosensitive intensity.

[0031] Optionally, in the above optical calibration method, the method for adjusting the polarization state of the analyzer module to match the target polarization state at least includes:

[0032] If the target polarization state is P polarization, adjust the analyzer module to the P-polarization analyzing state so that the calibration detection module can obtain the first calibration image corresponding to P polarization;

[0033] If the target polarization state is the S polarization, adjust the analyzer module to the S polarization detection state so that the calibration detection module can obtain the second calibration image corresponding to the S polarization.

[0034] Optionally, in the above optical calibration method, the optical calibration method further includes:

[0035] Determine the polarization transmittance based on the calibration image.

[0036] Optionally, in the above optical calibration method, calculating the polarization transmittance based on the calibration image includes:

[0037] Determine the polarization transmittance corresponding to the overall region of the calibration image based on the overall gray data of the calibration image;

[0038] And / or, divide the calibration image into multiple sub-regions, and determine the polarization transmittance corresponding to the sub-regions based on the gray data of the sub-regions.

[0039] Optionally, in the above optical calibration method, when the analyzer module is in the non-analyzer state, if the polarizer module is in the P polarization, the corresponding calibration image has the initial P polarization image gray value P 0 , if the polarizer module is in the S polarization, the corresponding calibration image has the initial S polarization image gray value S 0 ;

[0040] When the analyzer module is in the analyzer state, if the polarizer module is in the P polarization and the analyzer module is in the P analyzer state, the corresponding calibration image has the first P analyzer image gray value P 1 , and the transmittance is T PP , or if the analyzer module is in the S analyzer state, the corresponding calibration image has the first S analyzer image gray value S 1 , and the transmittance is T PS ; if the polarizer module is in the S polarization and the analyzer module is in the S analyzer state, the corresponding calibration image has the second S analyzer image gray value S 2 , and the transmittance is T SS , or if the analyzer module is in the P analyzer state, the corresponding calibration image has the second P analyzer image gray value P 2 , and the transmittance is T SP ;

[0041] Set the background image gray value to A; the method for calculating the polarization transmittance includes:

[0042] ;

[0043] ;

[0044] ;

[0045] 。

[0046] The third aspect of the present application provides a dark-field wafer inspection device, including: a wafer inspection module and the above-mentioned optical calibration system;

[0047] The optical calibration system includes:

[0048] An illumination system for providing an initial illumination beam;

[0049] A polarization module for applying polarization modulation to the initial illumination beam to form a polarized illumination beam;

[0050] An imaging system for collecting the polarized illumination beam after being scattered by the target to form a detection light;

[0051] A polarization analysis module for performing polarization screening on the detection light;

[0052] A pupil located on the light output side of the polarization analysis module and on the pupil plane of the imaging system;

[0053] A calibration detection module, and the dark-field wafer inspection device has a wafer inspection mode and a polarization transmittance calibration mode; in the polarization transmittance calibration mode, the calibration detection module is used to collect the detection light passing through the pupil to form a calibration image; the calibration image can at least characterize the polarization transmittance of the polarized illumination beam after being scattered;

[0054] Wherein, in the wafer inspection mode, the wafer inspection module is used to form a defect detection image based on the detection light, which can characterize the defect information of the wafer to be inspected.

[0055] By means of the above technical solutions, in the dark-field wafer inspection device, its optical calibration system and optical calibration method provided by the present application, a pupil is provided on the light output side of the imaging system, and the pupil is located on the pupil plane of the imaging system. The calibration detection module can obtain a calibration image based on the pupil plane of the pupil, and can perform imaging according to the detection light after passing through the scattering field. In the present application, at the position of the pupil plane of the imaging system, the scattered light will undergo spatial separation, and the calibration detection module can image the system pupil plane, and then can obtain the intensity distribution map of the pupil plane. The present application can control the polarization analysis conditions through the polarization analysis module, and based on the obtained calibration image, can accurately measure and calibrate the polarization transmittance of the illumination optical path to be measured relative to the scattering field. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] To more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0057] The structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those who are familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present application. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that the present application can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present application.

[0058] Figure 1 An optical path diagram of an optical calibration system provided for an embodiment of the application;

[0059] Figure 2 Images with different intensities formed by the calibration detection module in the optical calibration system on the set pupil plane and in the same polarization state;

[0060] Figure 3 An optical path diagram of the optical calibration system in the wafer detection mode;

[0061] Figure 4 Another optical path diagram of an optical calibration system provided for an embodiment of the present application;

[0062] Figure 5 A schematic flowchart of an optical calibration method provided for an embodiment of the present application;

[0063] Figure 6 A schematic flowchart of a method for calibrating the polarization state of a polarization module provided for an embodiment of the present application;

[0064] Figure 7 Another schematic flowchart of an optical calibration method provided for an embodiment of the present application;

[0065] Figure 8 Images with different intensities formed by the calibration detection module in the optical calibration system on the set pupil plane and in different polarization states.

[0066] Reference numerals:

[0067] 11 - Lighting system; 12 - Polarizer module; 13 - Imaging system; 14 - Target; 15 - Analyzer module; 16 - Pupil; 17 - Calibration detection module; 171 - In - cut mirror; 172 - Pupil imaging lens; 173 - First camera; 18 - Wafer detection module; 19 - Host computer; L1 - First optical axis; L2 - Second optical axis. Detailed implementation

[0068] The following will clearly and completely describe the embodiments in the present application with reference to the accompanying drawings in the embodiments of the present application. Those of ordinary skill in the art will know that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are equally applicable to similar technical problems.

[0069] As described in the background art, in order to correspond the polarization information with the detection result, an optical calibration system and an optical calibration method capable of determining the polarization transmittance after passing through the scattering field need to be designed.

[0070] Currently, the general conventional technical solution is to directly use an analyzer device to calibrate the polarization state of the lighting system. At this time, since the illumination beam has not yet irradiated the surface of the object to be measured, the calibration result of this solution has a deviation from the polarization state of the lighting system relative to the surface of the object to be measured. At the same time, the influence of the imaging system on the polarization state of the scattering field cannot be accurately reflected and analyzed by this solution.

[0071] To solve the above problems, the embodiments of the present application provide an optical calibration system. The optical calibration system is used for a dark - field wafer detection device, and the optical calibration system includes:

[0072] A lighting system for providing an initial illumination beam;

[0073] A polarizer module for applying polarization modulation to the initial illumination beam to form a polarized illumination beam;

[0074] An imaging system for collecting the polarized illumination beam after scattering by the target to form a detection light;

[0075] An analyzer module for performing polarization screening on the detection light;

[0076] A pupil located on the light - emitting side of the analyzer module and on the pupil plane of the imaging system;

[0077] A calibration detection module for collecting the detection light passing through the pupil to form a calibration image; the calibration image can at least characterize the polarization transmittance of the polarized illumination beam after scattering.

[0078] In the embodiments of the present application, a pupil is provided on the light-emitting side of the imaging system. The pupil is located on the pupil plane of the imaging system. The calibration detection module can obtain a calibration image based on the pupil plane and can perform imaging according to the detection light after passing through the scattering field. In the present application, at the position of the pupil plane of the imaging system, the scattered light will undergo spatial separation. The calibration detection module can image the system pupil plane, and thus can obtain the intensity distribution map of the pupil plane. The present application can control the polarization condition through the polarization analysis module. Based on the obtained calibration image, the polarization transmittance of the illumination optical path to be measured relative to the scattering field can be accurately measured and calibrated.

[0079] Since the illumination spot is very small, if the energy is directly collected, it will be very concentrated. The present application can collect the detection light through the pupil plane to form a calibration image. The detection light will be spatially separated on the pupil plane, which can avoid the problem of local overexposure of the detection camera in the calibration detection module.

[0080] In addition, there are differences in the polarization distribution within the aperture of the optical system (including the illumination system and the imaging system) in the wafer inspection equipment. Especially, the polarization states in the middle and at the edge are not the same. By collecting the detection light through the pupil plane to form a calibration image, it is possible to measure the polarization transmittance at the pupil plane, which is convenient for selecting key areas of concern for polarization transmittance calibration and analysis during subsequent data processing.

[0081] Moreover, by collecting the detection light through the pupil plane to form a calibration image and performing measurements at the pupil plane, in addition to intensity information, intensity distribution information can also be collected. When the polarization transmittance changes, it is convenient to judge the cause of the change, such as a change in the overall transmittance or a change in the local transmittance.

[0082] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0083] Refer to Figure 1 , Figure 1 which is an optical path diagram of an optical calibration system provided for an embodiment of the application. The optical calibration system is used for a dark-field wafer inspection device. The optical calibration system includes:

[0084] An illumination system 11 for providing an initial illumination beam;

[0085] A polarization module 12 for applying polarization modulation to the initial illumination beam to form a polarized illumination beam;

[0086] An imaging system 13 for collecting the polarized illumination beam after scattering by the target 14 to form detection light;

[0087] A polarization analysis module 15 for performing polarization screening on the detection light;

[0088] The pupil 16 is located on the light-emitting side of the analyzer module 15 and at the pupil plane of the imaging system 13. Optionally, the pupil 16 can be a device such as a diaphragm or an aperture.

[0089] The calibration detection module 17 is configured to collect the detection light passing through the pupil 16 to form a calibration image. The calibration image can at least characterize the polarization transmittance of the polarized illumination beam after scattering.

[0090] In the embodiment of the present application, a pupil is provided on the light-emitting side of the imaging system. The pupil 16 is located at the pupil plane of the imaging system 13. The calibration detection module 17 can obtain a calibration image based on the pupil plane of the pupil and can perform imaging according to the detection light after passing through the scattering field. In the present application, at the position of the pupil plane of the imaging system 13, the scattered light will be spatially separated. The calibration detection module 17 can image the system pupil plane, and thus can obtain the intensity distribution map of the pupil plane. The present application can control the polarization condition through the analyzer module 15. Based on the obtained calibration image, the polarization transmittance of the illumination optical path to be measured relative to the scattering field can be accurately measured and calibrated.

[0091] Based on the above description, it can be seen that the technical solution of the embodiment of the present application forms a calibration image based on the detection light after the optical system (including the illumination system 11 and the imaging system 13) passes through the target 14. Therefore, the calibration image can calibrate the polarization transmittance of the light after passing through the scattering field. This solution can calibrate the polarization transmittance based on the detection light entering the detection camera in the calibration detection module 17. Therefore, the calibration of the polarization transmittance of the optical system of the wafer detection device is more accurate, and the polarization transmittance after passing through the scattering field can be calibrated more precisely.

[0092] Reference Figure 2 , Figure 2 is the different intensity images formed by the calibration detection module in the optical calibration system at the set pupil plane and the same polarization state. At the set pupil plane and the same polarization state, if there is no abnormality in the optical system in the wafer detection device, the image formed by the calibration detection module is as shown in Figure 2 Figure (a) therein, and the intensity distribution of the overall image area is relatively uniform.

[0093] In the embodiment of the present application, by collecting the detection light through the pupil plane to form a calibration image and using the pupil plane as the sampling intensity information of the detection camera in the calibration detection module 17, the following technical effects can be achieved:

[0094] Since the illumination spot of the illumination system 11 is very small, if the energy is directly collected, the energy will be very concentrated, which will cause the problem of overexposure of the detection camera. The present application can collect the detection light through the pupil plane to form a calibration image. As shown in Figure 2As shown in Figure (a), since the detection light is spatially separated on the pupil plane, the intensity distribution of the overall area of the calibration image can be made uniform, which can avoid the problem of local overexposure of the detection camera in the calibration detection module 17.

[0095] In addition, there are differences in the polarization distribution of the optical system in the wafer inspection equipment within the aperture range. Especially, the polarization states in the middle and at the edge are not the same. By collecting the detection light through the pupil plane to form a calibration image, it is possible to measure the polarization transmittance at the pupil plane, which is convenient for selecting the key areas of concern for polarization transmittance calibration and analysis during subsequent data processing. As Figure 2 shown in Figure (b), the calibration image can be partitioned by a dashed circle and / or a dashed line. It can be seen that there are differences in the gray values between the outer and inner regions of the dashed circle, which reflects the differences in polarization transmittance at different partition positions. In some scenarios, the differences in polarization transmittance at the pupil plane are also reflected in different orientations. At this time, the differences in polarization transmittance in different orientations can be reflected by multiple fan-shaped regions divided by the dashed lines passing through the center of the circle.

[0096] Moreover, by collecting the detection light through the pupil plane to form a calibration image and measuring at the pupil plane, in addition to intensity information, intensity distribution information can also be collected. When the polarization transmittance changes, it is convenient to judge the cause of the change, such as the change in overall polarization transmittance or local polarization transmittance.

[0097] When there is an abnormality in the optical system of the wafer inspection equipment, it will cause a change in the overall polarization transmittance or local polarization transmittance. The manifestation on the calibration image is that the gray value changes relative to Figure 2 Figure (a).

[0098] For example, relative to Figure 2 Figure (a), Figure 2 in Figure (c), the gray value in the middle region significantly decreases. This change in polarization transmittance may be due to damage or contamination of the film layer of the optical element in the optical system.

[0099] As Figure 2 shown in Figure (d), when the wafer inspection equipment works for a long time in a specific detection scenario, the scattered light generates diffraction orders at fixed positions in the imaging system. This diffraction order causes irreversible damage to the coatings of some optical elements in the optical system. This damage will be manifested as a decrease in polarization transmittance and will appear in the gray-scale image of the pupil plane.

[0100] In the embodiments of the present application, the dark-field wafer inspection device has a wafer inspection mode and a polarization transmittance calibration mode. In the wafer inspection mode, the target 14 is the wafer to be inspected, and the illumination system 11, the polarization module 12, the imaging system 13, the analyzer module 15, and the pupil 16 are used to test the wafer to be inspected to determine whether there are defects. In the polarization transmittance calibration mode, the target 14 is a standard wafer, and the illumination system 11, the polarization module 12, the imaging system 13, the analyzer module 15, and the pupil 16 are used to determine the polarization transmittance after passing through the scattering field based on the standard wafer. Figure 1 It is an optical path diagram in the polarization transmittance calibration mode.

[0101] As Figure 1 shown, the calibration detection module 17 includes: an in-cut mirror 171, a pupil imaging mirror 172, and a first camera 173. The in-cut mirror 171 is movably placed in the optical calibration system. As Figure 1 shown by the hollow arrow in, the in-cut mirror 171 is used to be placed on the light-emitting side of the pupil 16 in the polarization transmittance calibration mode to reflect the detection light passing through the pupil 16 to the pupil imaging mirror 172; the pupil imaging mirror 172 is used to image the collected detection light to the target position of the first camera 173; the first camera 173 serves as the detection camera of the calibration detection module 17 and is used to form a calibration image based on the incident detection light.

[0102] Refer to Figure 3 , Figure 3 It is an optical path diagram of the optical calibration system in the wafer inspection mode. In the wafer inspection mode, the target 14 is the wafer to be inspected. As Figure 3 shown by the hollow arrow in, the in-cut mirror 171 is used to be placed outside the irradiation area of the light emitted from the pupil 16 so that the detection light passing through the pupil 16 can be incident on the wafer inspection module 18 coaxial with the imaging system 13. The wafer inspection module 18 is used to form a defect detection image that can characterize the defect information of the wafer to be inspected based on the detection light.

[0103] Optionally, the in-cut mirror 171 is installed on a movable member, and the movable member is not shown in the optical path system provided in the present application. The movable member can drive the in-cut mirror 171 to move horizontally or rotate; the movable member is used to drive the in-cut mirror 171 to be placed on the light-emitting side of the pupil 16 or drive the in-cut mirror 171 to be placed outside the irradiation area of the light emitted from the pupil 16.

[0104] Since the insertable mirror 171 can be movably placed in the optical calibration system, during the calibration operation, it can be moved into the light irradiation area so that the calibration detection module 17 can collect light to form a calibration image, facilitating the calibration of the polarization transmittance. In the wafer detection mode, it is placed outside the light irradiation area, thus not blocking the transmission of the wafer detection light and not affecting the normal defect detection of the dark-field wafer detection device.

[0105] The imaging system 13 has a first optical axis L1, and the calibration detection module 17 has a second optical axis L2. For the insertable mirror 171 that can be movably adjusted, the error in its position may cause differences in the reflection effect. In the embodiment of the present application, the wafer detection module 18 is set to be coaxial with the imaging system 13, and the first optical axis L1 and the second optical axis L2 are perpendicular, so that the light collection of the wafer detection module 18 does not pass through the insertable mirror 171, avoiding the influence of the above reflection effect differences on the detection effect of wafer defects and ensuring the accuracy of wafer defect detection. The wafer detection module 18 includes a second camera for imaging based on the detection light.

[0106] In other embodiments, when the placement control of the insertable mirror 171 has a high precision, the calibration detection module 17 can also be set to be coaxial with the imaging system 13, that is, the first optical axis L1 and the second optical axis L2 coincide. At this time, the optical axis of the wafer detection module 18 is perpendicular to the first optical axis L1. In this mode, in the wafer detection mode, the insertable mirror 171 is placed on the light output side of the pupil 16 to reflect the detection light passing through the pupil 16 to the wafer detection module 18, so that the wafer detection module 18 forms a defect detection image based on the detection light that can characterize the defect information of the wafer to be detected. In the polarization transmittance calibration mode, the insertable mirror 171 is placed outside the irradiation area of the light emitted from the pupil 16, so that the detection light passing through the pupil 16 can be incident on the pupil imaging mirror 172 and the first camera 173 that are coaxial with the imaging system 13, so that the first camera forms a calibration image.

[0107] Reference Figure 4 , Figure 4 is the optical path diagram of another optical calibration system provided by the embodiment of the present application. Based on any of the above embodiments, Figure 4 the optical calibration machine system shown further includes: a host computer 19 connected to the calibration detection module 17. The host computer 19 is used to determine the polarization transmittance based on the calibration image. The host computer has an image processing system and can automatically calculate the polarization transmittance through the built-in image processing algorithm.

[0108] Optionally, the host computer 19 is configured to determine the polarization transmittance corresponding to the overall area of the calibration image based on the overall gray data of the calibration image; or, the host computer 19 is configured to divide the calibration image into multiple sub-regions, and determine the polarization transmittance corresponding to the sub-regions based on the gray data of the sub-regions, or the host computer 19 is configured to determine the polarization transmittance corresponding to the overall area of the calibration image based on the overall gray data of the calibration image, and is further configured to divide the calibration image into multiple sub-regions, and determine the polarization transmittance corresponding to the sub-regions based on the gray data of the sub-regions.

[0109] In the optical calibration system provided by the embodiments of the present application, an initial illumination beam is provided by the illumination system 11. After the polarization modulation is applied to the initial illumination beam by the polarization module 12, a polarized illumination beam can be formed. The polarized illumination beam is obliquely incident on the surface of the target 14 based on a set inclination angle. As described above, when used to calibrate the polarization transmittance, the target 14 is a standard sheet with a set roughness (generally in the order of a few nanometers to more than a dozen nanometers), so that the scattering intensity after passing through the standard sheet meets the system detection requirements. The detection light formed by the scattering of the standard sheet passes through the imaging system 13, and then through the polarization screening of the analyzer module 15, and the light rays that meet the analyzer conditions are reflected by a cut-in mirror 171 to the pupil imaging mirror 172, and the pupil plane is imaged to the first camera 173 through the pupil imaging mirror 172. The first camera 173 can collect the intensity information of the detection light at the pupil plane, and the collected intensity information can be characterized by the calibration image formed by the first camera 173, and can be used to calibrate the polarization transmittance of the light rays after scattering by the standard sheet.

[0110] Based on the optical calibration system provided by the above embodiments, another embodiment of the present application further provides an optical calibration method for an optical calibration system, and this method can be as Figure 5 shown.

[0111] Refer to Figure 5 , Figure 5 which is a schematic flow chart of an optical calibration method provided by an embodiment of the present application. This optical calibration method includes:

[0112] Step S11: After calibrating the polarization state of the polarization module 12, turn on the illumination system 11, and emit an initial illumination beam through the illumination system 11; wherein, the initial illumination beam forms a polarized illumination beam obliquely incident on the target 14 after the polarization modulation is applied by the polarization module 12, and the target 14 is a standard sheet with a set roughness; the polarized illumination beam after scattering by the standard sheet forms detection light through the imaging system 13; the detection light is incident on the calibration detection module 17 through the pupil 16.

[0113] Step S12: After forming a polarized illumination beam with a target polarization state through the polarizing module 12, adjust the polarization state of the analyzer module 15 to match the target polarization state.

[0114] Step S13: Obtain a calibration image corresponding to the target polarization state through the calibration detection module 17; the calibration image can at least characterize the polarization transmittance after the polarized illumination beam passes through scattering.

[0115] Based on the optical calibration system provided by the above embodiments, the optical calibration method as shown in Figure 5 can be realized, and the polarization transmittance after passing through the scattering field can be accurately calibrated.

[0116] As described above, based on the optical calibration system provided by the embodiments of the present application, the optical calibration method directly collects and images the scattered light entering the detection camera, and the collected light already contains the influence of the entire optical system (illumination system 11 and imaging system 13) in the dark field pattern detection device on the polarization state. Therefore, the calibration of the polarization transmittance of the optical system is more accurate.

[0117] In addition, in the optical calibration method, after the polarized illumination beam is scattered by the object surface of the target 14, the imaging system 13 receives the scattered light (the detection light formed by scattering through the target 14), samples the intensity information of the scattered light at a set position using the first camera 173 in the calibration detection module 17, and the intensity information is characterized by the gray value of the first camera 173. By controlling the polarization conditions in front of the pupil plane, the polarization transmittance of the entire optical system relative to the scattering object surface can be measured more accurately.

[0118] As described above, the optical calibration system is used for a dark field wafer detection device, and the dark field wafer detection device has a wafer detection mode and a polarization transmittance calibration mode; the calibration detection module 17 includes: a cut-in mirror 171, a pupil imaging mirror 172, and a first camera 173.

[0119] When performing polarization transmittance calibration based on the optical calibration method, in the polarization transmittance calibration mode, as shown in Figure 1 , place the cut-in mirror 171 on the light output side of the pupil 16 to reflect the detection light passing through the pupil 16 to the pupil imaging mirror 172, image the collected detection light to the target surface position of the first camera 173 through the pupil imaging mirror 172, and collect the detection light through the first camera 173 to form a calibration image.

[0120] When performing polarization transmittance calibration based on the optical calibration method, in the wafer detection mode, as shown in Figure 3As shown, the cutting-in mirror 171 is placed outside the illumination area of the light rays emitted from the pupil 16, so that the detection light passing through the pupil 16 can be incident on the wafer detection module 18 coaxial with the imaging system 13, and the wafer detection module 18 forms a defect detection image capable of characterizing the defect information of the wafer to be detected based on the detection light.

[0121] Reference Figure 6 , Figure 6 FIG. is a schematic flowchart of a method for calibrating the polarization state of a polarization module provided by an embodiment of the present application. The method for calibrating the polarization state of the polarization module 12 includes:

[0122] Step S21: After adjusting the analyzer module 15 to a non-analyzing state, the calibration detection module 17 collects a background image under the condition of no initial illumination beam illumination.

[0123] Step S22: After turning on the illumination system, rotate the polarization module 12 to find the first polarization position, the second polarization position, and the third polarization position of the polarization module 12; at the first polarization position, the first camera 173 in the calibration detection module 17 has the maximum photosensitive intensity, and the polarization illumination beam has P polarization; at the second polarization position, the first camera 173 has the minimum photosensitive intensity, and the polarization illumination beam has S polarization; at the third polarization position, the photosensitive intensity of the first camera 173 is between the maximum photosensitive intensity and the minimum photosensitive intensity, and the polarization illumination beam has circular polarization.

[0124] Based on Figure 6 the method shown, the polarization state of the polarization module 12 can be calibrated. When actually detecting a wafer using an optical system, if wafers of different materials and roughnesses are replaced, the wafer defect detection results can be corrected based on the calibration result to improve the accuracy and precision of wafer defect detection.

[0125] In the optical calibration method provided by the embodiment of the present application, the method for adjusting the polarization state of the analyzer module 15 to match the target polarization state at least includes: if the target polarization state is P polarization, adjust the analyzer module 15 to the P polarization analyzing state so that the calibration detection module 17 can obtain the first calibration image corresponding to P polarization; if the target polarization state is S polarization, adjust the analyzer module 15 to the S polarization detection state so that the calibration detection module 17 can obtain the second calibration image corresponding to S polarization.

[0126] Reference Figure 7 , Figure 7 FIG. is a schematic flowchart of another optical calibration method provided by an embodiment of the present application. On the basis of the above embodiment, Figure 7 the optical calibration method shown further includes:

[0127] Step S14: Calculate the polarization transmittance based on the calibration image.

[0128] In Figure 7 the manner shown, image processing can be automatically performed based on the host computer 19 to automatically determine the polarization transmittance according to the calibration image obtained by the calibration detection module 17.

[0129] Optionally, in step S14, determining the polarization transmittance based on the calibration image includes: determining the polarization transmittance corresponding to the overall area of the calibration image based on the overall gray data of the calibration image; and / or dividing the calibration image into multiple sub-regions, and determining the polarization transmittance corresponding to the sub-regions based on the gray data of the sub-regions.

[0130] Reference Figure 8 , Figure 8 is the different intensity images formed by the calibration detection module in the optical calibration system at the set pupil plane and different polarization states. During the process of calibrating the polarization transmittance by the optical calibration method provided by the embodiments of the present application, the analyzer module 15 is in a non-analyzing state. The calibration image corresponding to P polarization is as shown in Figure 8 Figure (a) in; the calibration image corresponding to circular polarization is as shown in Figure 8 Figure (b) in; the calibration image corresponding to S polarization is as shown in Figure 8 Figure (c) in; the background image is as shown in Figure 8 Figure (d) in.

[0131] Next, in combination with the optical calibration system provided by the above embodiments, the optical calibration method provided by the embodiments of the present application will be further described. The optical calibration method includes:

[0132] First step, the illumination system 11 can use a deep ultraviolet coherent light source for illumination, adopt an oblique incident dark field illumination method, and illuminate the spot of the polarized illumination beam formed by the polarization module 12 on a standard sheet with a set roughness so that the scattering intensity meets the detection requirements.

[0133] Second step, as shown in Figure 1 , place the cut-in mirror 171 at a set position on the light output side of the pupil 16. The cut-in mirror 171 is located in the optical path between the pupil plane and the pupil imaging mirror 172. The analyzer module 15 is adjusted to be empty so that it is in a non-analyzing state. At this time, the first camera 173 can collect the detection light intensity distribution of the pupil plane.

[0134] Then, based on the following third step and fourth step, the polarization state of the polarization module 12 can be calibrated.

[0135] In the third step, close the shutter in the illumination system 11 so that the illumination system 11 does not emit the initial illumination beam. At this time, the first camera 173 can collect the background image under the condition of no illumination to obtain the background intensity. Among them, the background image is as shown in Figure 8 Figure (d) in

[0136] In the fourth step, open the shutter in the illumination system so that the illumination system emits the initial illumination beam, so that the calibration detection module 17 can use the detection light intensity under normal illumination conditions. In this step, rotate the polarization module 12 to find the first polarization position corresponding to the maximum photosensitive intensity of the first camera 173. Based on the polarized incident condition, the initial illumination light is polarized light. At the first polarization position, due to the maximum photosensitive intensity, the light intensity of the scattering field is the largest at this time, and the gray value in the calibration image is the largest. Therefore, at this position, the polarization module 12 is consistent with the polarization of the initial illumination beam. It is calibrated that the polarization module 12 has P polarization at this time, and the emitted polarized illumination beam has P polarization. Among them, the calibration image corresponding to P polarization is as shown in Figure 8 Figure (a) in Figure 8 After the P polarization calibration of the polarization module 12 is completed, the first polarization position corresponding to the polarization module 12 is confirmed. On this basis, other polarization states can be adjusted according to the quantitative angular position. Then, the pupil plane gray value is collected by the first camera 173 in other polarization states to achieve the purpose of calibrating the polarization transmittance of these polarization states. For example, when the polarization module 12 is rotated to the second polarization position, the calibration image of S polarization as shown in Figure 8 Figure (c) in can be obtained. When the polarization module 12 is rotated to the third polarization position, the calibration image of circular polarization as shown in Figure (b) in

[0137]

[0138] can be obtained. Among them, relative to P polarization, the light intensity of the scattering field is the smallest in S polarization, and the image gray value in the calibration image is the smallest. The scattering field intensity of circular polarization is between the scattering field intensities corresponding to P polarization and S polarization, so the gray value of its corresponding calibration image is also between the maximum image gray value and the minimum image gray value. The difference between the image gray value of P polarization and the background image gray value can be used as the relative gray value of P polarization, and the relative gray value of P polarization is set to 1. Based on the relative gray value of P polarization, the corresponding relative gray values under circular polarization and S polarization can be obtained. Calculate the ratio of the relative gray value of circular polarization to P polarization and the ratio of the relative gray value of S polarization to P polarization. These two ratios are generally determined by the roughness of the scattering surface and the material. After the polarization state calibration of the polarization module 12 is completed, when actually monitoring the surface defects of the wafer, for wafers of different materials and roughnesses, the defect detection results need to be corrected based on the above ratios to improve the defect detection accuracy and accuracy.Step 6: After calibrating the polarization state of the polarizer module 12, it is necessary to further calibrate the polarization transmittance of the analyzer module 15 in different analyzer states. In this step, when the polarizer module 12 is in the target polarization state, the analyzer state of the analyzer module 15 is correspondingly switched to be corresponding to the target polarization state. The analyzer module 15 is in the analyzer state adapted to the polarizer module 12, and the calibration images in different target polarization states are respectively captured by the first camera 173. The target polarization states include but are not limited to P polarization and S polarization. If the polarizer module 12 is in P polarization and the target polarization state is P polarization, correspondingly, the analyzer module 15 is in the P analyzer state. If the polarizer module 12 is in S polarization and the target polarization state is S polarization, the corresponding analyzer module 15 is in the S analyzer state. During the process of calibrating the polarization transmittance of the analyzer module 15 in different analyzer states, the first camera 173 is used to respectively obtain the calibration images corresponding to the analyzer module 15 in different analyzer states to record the determined gray values.

[0139] When the analyzer module 15 is in the non-analyzer state, if the polarizer module 12 is in P polarization, it is set that the calibration image has the initial P-polarized image gray value P 0 , if the polarizer module 12 is in S polarization, it is set that the calibration image has the initial S-polarized image gray value S 0 . When the analyzer module 15 is in the analyzer state, if the polarizer module 12 is in P polarization and the analyzer module 15 is in the P analyzer state, it is set that the calibration image has the first P-analyzer image gray value P 1 , and the transmittance is T PP , or when the analyzer module is in the S analyzer state, the corresponding calibration image has the first S-analyzer image gray value S 1 , and the transmittance is T PS ; if the polarizer module 12 is in S polarization and the analyzer module 15 is in the S analyzer state, it is set that the calibration image has the second S-analyzer image gray value S 2 , and the transmittance is T SS , or when the analyzer module is in the P analyzer state, the corresponding calibration image has the second P-analyzer image gray value P 2 , and the transmittance is T SP . The background image gray value is set to A, and the methods for calculating the polarization transmittance include calculating T PP , T PS , T SS and T SP , T PP , T PS , T SS and T SP . The calculation methods of T

[0140] ;

[0141] ;

[0142] ;

[0143] 。

[0144] By calibrating the polarization transmittance of the analyzer module 15 in different polarization states, T can be calculated and obtained. PP 、T PS 、T SS and T SP . Based on T PP 、T PS 、T SS and T SP , the transmittance and extinction ratio of the analyzer module 15 can be confirmed, which can be used to assist in judging the depolarization information of the scattering surface, etc. If the analyzer module 15 is in the P polarization state, the extinction ratio is T PP / T SP . If the analyzer module 15 is in the S polarization state, the extinction ratio is T SS / T PS . For an ideal optical device, T PS and T SP are equal to 0. In an actual optical device, both are non-zero values.

[0145] In the above calibration, the overall gray-scale data of the calibration image is collected as the calibration parameter. In some scenarios, it is necessary to pay attention to the change of the transmittance in the local area. Based on this, in the embodiments of the present application, the calibration image can also be divided into multiple sub-regions, and based on the division of the sub-regions, the polarization transmittance of the local area to be concerned about is calibrated. It can be as shown in Figure 2 Figure (b) for sub-region division. Based on the dashed circle, the calibration image is divided into a circular sub-region inside the dashed circle and an annular sub-region outside the dashed circle. Based on the perpendicular and intersecting dashed lines, the calibration image is divided into four sector sub-regions corresponding to four different orientations. Based on the divided sub-regions, the image gray-scale values corresponding to the set sub-regions in the polarization state and non-polarization state can be obtained in the same way as in the fifth and sixth steps above, and TP and TS are calculated respectively based on the same calculation principle to achieve the calibration of the polarization transmittance of the set sub-region.

[0146] Based on the optical calibration system and optical calibration method provided in the above embodiments, another embodiment of the present application also provides a dark-field pattern detection device. Combining the optical path diagram of the above embodiments, the dark-field wafer detection device includes: a wafer detection module 18 and the optical calibration system provided in the above embodiments;

[0147] The optical calibration system includes:

[0148] An illumination system 11, and the illumination system 11 is used to provide an initial illumination beam;

[0149] A polarizing module 12, which is configured to apply polarization modulation to an initial illumination beam to form a polarized illumination beam;

[0150] An imaging system 13, which is configured to collect the polarized illumination beam after being scattered by a target 14 to form a detection light;

[0151] An analyzer module 15, which is configured to perform polarization screening on the detection light;

[0152] A pupil 16, which is located on the light output side of the analyzer module 15 and is configured to provide a set pupil plane;

[0153] A calibration detection module 17, and the dark-field wafer detection device has a wafer detection mode and a polarization transmittance calibration mode; in the polarization transmittance calibration mode, the calibration detection module 17 is configured to collect the detection light passing through the pupil 16 to form a calibration image; the calibration image can at least characterize the polarization transmittance of the polarized illumination beam after being scattered;

[0154] Wherein, in the wafer detection mode, a wafer detection module 18 is configured to form a defect detection image capable of characterizing the defect information of the wafer to be detected based on the detection light.

[0155] Optionally, the wafer can be a patterned wafer or a non-patterned wafer, and the embodiments of the present application do not limit the type of wafer as the object to be detected.

[0156] The dark-field wafer detection device provided by the embodiments of the present application includes the above-mentioned optical calibration system, and has two working modes, which can not only be used for wafer defect detection, but also be used for calibrating the polarization transmittance of its own optical system.

[0157] In the description of the present application, each embodiment is described in a progressive, or parallel, or a combination of progressive and parallel manners. The key points of each embodiment are the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. The embodiments provided by the embodiments of the present application can be combined with each other without conflict.

[0158] It should be noted that in the description of the present application, it should be understood that the descriptions of the drawings and embodiments are illustrative rather than restrictive. The same reference numerals throughout the embodiments of the specification identify the same structures. Additionally, for the sake of understanding and ease of description, some layers, films, panels, regions, etc. may be exaggerated in thickness in the drawings. At the same time, it can be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, the element can be directly on the other element or there may be intermediate elements. Additionally, "on" means positioning the element on or below another element, but does not inherently mean positioning on the upper side of another element according to the direction of gravity.

[0159] The orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be intermediate components present at the same time.

[0160] It should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including", or any other variation thereof is intended to cover non-exclusive inclusion, such that an article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements that are inherent to such article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the article or device comprising the above elements.

[0161] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optical calibration system, characterized in that: The optical calibration system is used for dark field wafer detection equipment, and the optical calibration system includes: an illumination system, the illumination system being used to provide an initial illumination beam; A polarizing module, the polarizing module is used to apply polarization modulation to the initial illumination light beam to form a polarized illumination light beam; An imaging system, the imaging system is used to collect the polarized illumination light beam after being scattered by the target component to form a detection light; A polarization analyzer module, the polarization analyzer module is used to perform polarization screening on the detection light; A pupil, the pupil is located at the light exit side of the polarization analyzer module and at the pupil plane of the imaging system; A calibration detection module, the calibration detection module is used to collect detection light passing through the pupil to form a calibration image; the calibration image can at least characterize the polarization transmittance of the polarized illumination light beam after scattering; The dark field wafer inspection equipment has a wafer inspection mode and a polarization transmittance calibration mode; the calibration inspection module includes: a cut-in reflector, a pupil imaging mirror and a first camera; wherein the cut-in reflector can be movably placed in the optical calibration system; the cut-in reflector is used to be placed on the light exit side of the pupil in the polarization transmittance calibration mode to reflect the inspection light passing through the pupil to the pupil imaging mirror; the pupil imaging mirror is used to image the collected inspection light to the target surface position of the first camera; the first camera is used to form the calibration image based on the incident inspection light.

2. The optical calibration system according to claim 1, characterized in that: in, In the wafer inspection mode, the target part is a wafer to be inspected, and the cut-in reflector is used to be placed outside the irradiation area of ​​the pupil exit light, so that the detection light passing through the pupil can be incident on a wafer inspection module that has a common optical axis with the imaging system. The wafer inspection module is used to form a defect detection image that can characterize the defect information of the wafer to be inspected based on the detection light.

3. The optical calibration system according to claim 2, characterized in that: The cut-in reflector is mounted on a movable part; Among them, the movable part can drive the cut-in reflector to move horizontally or rotationally; the movable part is used to drive the cut-in reflector to be placed on the light exit side of the pupil, or drive the cut-in reflector to be placed outside the illumination area of ​​the pupil exit light.

4. The optical calibration system according to claim 1, characterized in that: It also includes a host computer connected to the calibration detection module, and the host computer is used to determine the polarization transmittance based on the calibration image.

5. The optical calibration system according to claim 4, characterized in that: The host computer is used to determine the polarization transmittance corresponding to the entire area of ​​the calibration image based on the overall grayscale data of the calibration image; And / or, the host computer is used to divide the calibration image into multiple sub-regions, and determine the polarization transmittance corresponding to the sub-region based on the grayscale data of the sub-region.

6. An optical calibration method for an optical calibration system according to any one of claims 1 to 5, characterized in that: include: After calibrating the polarization state of the polarizing module, the illumination system is turned on, and an initial illumination beam is emitted through the illumination system; wherein the initial illumination beam is subjected to polarization modulation by the polarizing module to form a polarized illumination beam obliquely incident on the target part, and the target part is a standard film with a set roughness; the polarized illumination beam scattered by the standard film passes through the imaging system to form detection light; the detection light is incident on the calibration detection module through the pupil; After the polarized illumination light beam having a target polarization state is formed by the polarizing module, the analyzing state of the analyzing module is adjusted to be adapted to the target polarization state; Acquiring a calibration image corresponding to the target polarization state through the calibration detection module; the calibration image can at least characterize the polarization transmittance of the polarized illumination light beam after scattering; The optical calibration system is used for dark-field wafer inspection equipment, and the dark-field wafer inspection equipment has a wafer inspection mode and a polarization transmittance calibration mode; the calibration inspection module includes: a cut-in reflector, a pupil imaging mirror and a first camera; the cut-in reflector is movably placed in the optical calibration system; in the polarization transmittance calibration mode, the cut-in reflector is placed on the light exit side of the pupil to reflect the detection light passing through the pupil to the pupil imaging mirror, and the collected detection light is imaged to the target surface position of the first camera through the pupil imaging mirror, and the detection light is collected by the first camera to form the calibration image.

7. The optical calibration method according to claim 6, characterized in that: In the wafer inspection mode, the cut-in reflector is placed outside the illumination area of ​​the pupil exit light, so that the detection light passing through the pupil can be incident on a wafer inspection module that has a common optical axis with the imaging system, so that the wafer inspection module forms a defect detection image that can characterize the defect information of the wafer to be inspected based on the detection light.

8. The optical calibration method according to claim 6, characterized in that: The method for calibrating the polarization state of the polarization module includes: After adjusting the polarization analyzer module to a non-polarization analyzer state, collecting a background image under the illumination condition without the initial illumination beam through the calibration detection module; After turning on the illumination system, the polarizing module is rotated to find a first polarization position, a second polarization position, and a third polarization position of the polarizing module; at the first polarization position, the first camera in the calibration detection module has a maximum photosensitivity, and the polarized illumination beam has a P polarization; at the second polarization position, the first camera has a minimum photosensitivity, and the polarized illumination beam has an S polarization; at the third polarization position, the photosensitivity of the first camera is between the maximum photosensitivity and the minimum photosensitivity, and the polarized illumination beam has a circular polarization.

9. The optical calibration method according to claim 6, characterized in that: The method of adjusting the polarization state of the polarization analyzer module to adapt to the target polarization state at least includes: If the target polarization state is P polarization, adjusting the polarization analyzer module to a P polarization polarization analyzer state, so that the calibration detection module can obtain a first calibration image corresponding to the P polarization; If the target polarization state is S polarization, the polarization analyzer module is adjusted to the S polarization detection state, so that the calibration detection module can obtain a second calibration image corresponding to the S polarization.

10. The optical calibration method according to any one of claims 6 to 9, characterized in that: The optical calibration method further comprises: The polarization transmittance is calculated based on the calibration image.

11. The optical calibration method according to claim 10, characterized in that: Calculating the polarization transmittance based on the calibration image includes: Determining the polarization transmittance corresponding to the entire area of ​​the calibration image based on the overall grayscale data of the calibration image; And / or, the calibration image is divided into a plurality of sub-regions, and based on the grayscale data of the sub-regions, the polarization transmittance corresponding to the sub-regions is determined.

12. The optical calibration method according to claim 10, characterized in that: When the polarization analyzer module is in a non-polarization analyzer state, if the polarization module is in P polarization, the corresponding calibration image has an initial P polarization image grayscale value P0, and if the polarization module is in S polarization, the corresponding calibration image has an initial S polarization image grayscale value S0; When the polarization analyzer module is in the polarization analyzer state, if the polarization module is in the P polarization state, the polarization analyzer module is in the P polarization analyzer state, and the corresponding calibration image has a first P polarization analyzer image grayscale value P1, and the transmittance is T PP , or the polarization module is in the S polarization state, and the corresponding calibration image has a first S polarization image grayscale value S1, and the transmittance is T PS If the polarizing module is in S polarization, the polarization analyzing module is in S polarization state, the corresponding calibration image has a second S polarization image gray value S2, and the transmittance is T SS , or the polarization module is in the P polarization state, and the corresponding calibration image has a second P polarization image grayscale value P2, and the transmittance is T SP ; Set the gray value of the background image to A; The method for calculating the polarization transmittance includes: 。 13. A dark field wafer inspection device, characterized in that: include: A wafer inspection module and an optical calibration system as claimed in any one of claims 1 to 5; The optical calibration system comprises: an illumination system, the illumination system being used to provide an initial illumination beam; A polarizing module, the polarizing module is used to apply polarization modulation to the initial illumination light beam to form a polarized illumination light beam; An imaging system, the imaging system is used to collect the polarized illumination light beam after being scattered by the target component to form a detection light; A polarization analyzer module, the polarization analyzer module is used to perform polarization screening on the detection light; A pupil, the pupil is located at the light exit side of the polarization analyzer module and at the pupil plane of the imaging system; A calibration detection module, wherein the dark field wafer detection device has a wafer detection mode and a polarization transmittance calibration mode; in the polarization transmittance calibration mode, the calibration detection module is used to collect the detection light passing through the pupil to form a calibration image; the calibration image can at least characterize the polarization transmittance of the polarized illumination light beam after scattering; Wherein, in the wafer inspection mode, the wafer inspection module is used to form a defect inspection image capable of representing defect information of the wafer to be inspected based on the inspection light.

Images