Dark field wafer detection equipment and optical calibration system and optical calibration method thereof

Abstract

The invention discloses dark field wafer detection equipment and an optical calibration system and an optical calibration method thereof, and relates to the technical field of wafer detection equipment, a pupil is arranged on the light emitting side of an imaging system, the pupil is located on the pupil plane of the imaging system, and a calibration detection module can obtain a calibration image based on the pupil plane. Imaging can be performed according to the detection light passing through the scattered field. In the application, the scattered light is spatially separated at the pupil plane position of the imaging system, and the calibration detection module can image the pupil plane of the system, so that the intensity distribution diagram of the pupil plane can be obtained. The polarization detection condition can be controlled through the polarization detection module, and the polarization transmittance of the to-be-measured illumination light path relative to the scattered field can be accurately measured and calibrated based on the obtained calibration image.

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 and an optical calibration system and an optical calibration method thereof. Background Art

[0002] Dark field wafer inspection equipment is a key device used to detect defects in wafers during the semiconductor manufacturing process. The main working principle of dark field wafer inspection equipment is: the lighting system emits light to illuminate 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 the defects in the wafer can be identified based on the image obtained by the detection camera.

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

[0004] In view of the above problems, the present application provides a dark field wafer inspection device and an optical calibration system and an optical calibration method thereof, so as to achieve the purpose of determining the polarization transmittance after passing through the scattered field. The specific scheme is as follows:

[0005] The first aspect of the present application provides an optical calibration system, the optical calibration system is used for a dark field wafer inspection device, and the optical calibration system includes:

[0006] A lighting system, the lighting system is used to provide an initial lighting beam;

[0007] A polarizing module, the polarizing module is used to apply polarization modulation to the initial illumination beam to form a polarized illumination beam;

[0008] An imaging system, the imaging system is used to collect the polarized illumination light beam after being scattered by the target object to form a detection light;

[0009] Polarization analyzer module, which is used to perform polarization screening on the detection light;

[0010] A pupil, which is located at the light exit side of the analyzer module and at the pupil plane of the imaging system;

[0011] 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.

[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 incision reflector, a pupil imaging mirror and a first camera; wherein the incision reflector is movably placed in the optical calibration system; the incision reflector is used to be placed on the light exit 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] Among them, in the wafer inspection mode, the target part is the 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 the wafer inspection module that has the same optical axis as 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.

[0015] Optionally, in the above optical calibration system, the cut-in reflector is mounted on the movable member;

[0016] 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 to drive the cut-in reflector to be placed outside the illumination area of ​​the pupil exit light.

[0017] Optionally, the above optical calibration system 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 entire area of ​​the calibration image based on the overall grayscale 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-region based on the grayscale data of the sub-region.

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

[0021] After the polarization state of the polarization module is calibrated, 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 polarization module to form a polarized illumination beam obliquely incident on a target piece, and the target piece is a standard piece with a set roughness; the polarized illumination beam scattered by the standard piece is passed through an imaging system to form a detection light; and the detection light is incident on the calibration detection module through the pupil;

[0022] After a polarized illumination beam having a target polarization state is formed by a polarizing module, the polarization state of the polarization analyzing module is adjusted to be adapted to the target polarization state;

[0023] A calibration image corresponding to the target polarization state is obtained through the calibration detection module; the calibration image can at least characterize the polarization transmittance of the polarized illumination light beam after 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: a cutting-in reflector, a pupil imaging mirror and a first camera; the cutting-in reflector can be movably placed in the optical calibration system;

[0026] In the polarization transmittance calibration mode, a 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, the collected detection light is imaged to the target surface position of the first camera by the pupil imaging mirror, and the detection light is collected by the first camera to form a calibration image;

[0027] In 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 the wafer inspection module that has the same optical axis as 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.

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

[0029] After the polarization analyzer module is adjusted to a non-polarization analyzer state, a background image under the illumination condition without the initial illumination beam is collected by the calibration detection module;

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

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

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

[0033] 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 the second calibration image corresponding to the S polarization.

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

[0035] Based on the calibration image, the polarization transmittance is determined.

[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 entire area of ​​the calibration image based on the overall grayscale data of the calibration image;

[0038] And / or, the calibration image is divided into a plurality of sub-regions, and the polarization transmittance corresponding to the sub-region is determined based on the grayscale data of the sub-region.

[0039] Optionally, in the above optical calibration method, when the polarization analyzing module is in a non-polarization analyzing state, if the polarizing module is in P polarization, the corresponding calibration image has an initial P polarization image grayscale value P0, and if the polarizing module is in S polarization, the corresponding calibration image has an initial S polarization image grayscale value S0;

[0040] When the polarization module is in the polarization state, if the polarization module is in P polarization, the polarization module is in P polarization state, and the corresponding calibration image has a first P polarization image gray value P1, and the transmittance is T PP , or the polarization module is in the S polarization state, the corresponding calibration image has the first S polarization image gray value S1, and the transmittance is T PS If the polarizing module is in S polarization and the analyzing module is in S analyzing state, the corresponding calibration image has a second S analyzing image gray value S2 and a transmittance of T SS , or the polarization module is in the P polarization state, the corresponding calibration image has a second P polarization image gray value P2, and the transmittance is T SP ;

[0041] The gray value of the background image is set to A; the method for calculating the polarization transmittance includes:

[0042] ;

[0043] ;

[0044] ;

[0045] .

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

[0047] The optical calibration system includes:

[0048] A lighting system, the lighting system is used to provide an initial lighting beam;

[0049] A polarizing module, the polarizing module is used to apply polarization modulation to the initial illumination beam to form a polarized illumination beam;

[0050] An imaging system, the imaging system is used to collect the polarized illumination light beam after being scattered by the target object to form a detection light;

[0051] Polarization analyzer module, which is used to perform polarization screening on the detection light;

[0052] A pupil, which is located at the light exit side of the analyzer module and at the pupil plane of the imaging system;

[0053] Calibration detection module, the dark field wafer detection equipment 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 beam after scattering;

[0054] Among them, in the wafer inspection mode, the wafer inspection module is used to form a defect inspection image that can represent the defect information of the wafer to be inspected based on the inspection light.

[0055] By means of the above technical scheme, in the dark-field wafer inspection equipment and its optical calibration system and optical calibration method provided by the present application, a pupil is arranged on the light-exiting side of the imaging system, and the pupil is located at 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 based on the detection light after passing through the scattered field. In the present application, at the position of the pupil plane of the imaging system, the scattered light will be spatially separated, and the calibration detection module can image the pupil plane of the system, and then obtain the intensity distribution diagram of the pupil plane. The present application can control the polarization condition through the polarization analysis module, and based on the obtained calibration image, the polarization transmittance of the illumination light path to be measured relative to the scattered field can be accurately measured and calibrated. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0057] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which this application can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by this application, should still fall within the scope of the technical contents disclosed in this application.

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

[0059] Figure 2 Different intensity images formed by the calibration detection module in the optical calibration system under the set pupil plane and the same polarization state;

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

[0061] Figure 4 A light path diagram of another optical calibration system provided in an embodiment of the present application;

[0062] Figure 5 A schematic diagram of a flow chart of an optical calibration method provided in an embodiment of the present application;

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

[0064] Figure 7 A schematic diagram of a flow chart of another optical calibration method provided in an embodiment of the present application;

[0065] Figure 8 It is an image of different intensities formed by the calibration detection module in the optical calibration system under the set pupil plane and different polarization states.

[0066] Reference numerals:

[0067] 11-illumination system; 12-polarizing module; 13-imaging system; 14-target part; 15-polarizing module; 16-pupil; 17-calibration detection module; 171-cut-in reflector; 172-pupil imaging mirror; 173-first camera; 18-wafer detection module; 19-host computer; L1-first optical axis; L2-second optical axis. DETAILED DESCRIPTION

[0068] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the embodiments of the present application. It is known to those skilled in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0069] As described in the background art, in order to match the polarization information with the detection results, it is necessary to design an optical calibration system and an optical calibration method that can determine the polarization transmittance after passing through the scattered field.

[0070] At present, the conventional technical solution is generally to directly use a polarization analyzer to calibrate the polarization state of the illumination system. At this time, since the illumination beam has not yet irradiated the object surface to be measured, there is a deviation between the calibration result of this solution and the polarization state of the illumination system relative to the object surface to be measured. At the same time, the influence of the imaging system on the polarization state of the scattered field cannot be accurately reflected and analyzed through this solution method.

[0071] In order to solve the above problems, an embodiment of the present application provides an optical calibration system, which is used for dark field wafer inspection equipment. The optical calibration system includes:

[0072] A lighting system, the lighting system is used to provide an initial lighting beam;

[0073] A polarizing module, the polarizing module is used to apply polarization modulation to the initial illumination beam to form a polarized illumination beam;

[0074] An imaging system, the imaging system is used to collect the polarized illumination light beam after being scattered by the target object to form a detection light;

[0075] Polarization analyzer module, which is used to perform polarization screening on the detection light;

[0076] A pupil, which is located at the light exit side of the analyzer module and at the pupil plane of the imaging system;

[0077] 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.

[0078] In an embodiment of the present application, a pupil is provided on the light exit side of the imaging system, and the pupil is located at 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 based on the detection light after passing through the scattered field. In the present application, at the position of the pupil plane of the imaging system, the scattered light will be spatially separated, and the calibration detection module can image the pupil plane of the system, and then obtain the intensity distribution diagram of the pupil plane. The present application can control the polarization condition through the polarization analysis module, and based on the obtained calibration image, the polarization transmittance of the illumination light path to be measured relative to the scattered field can be accurately measured and calibrated.

[0079] Since the illumination spot is very small, if the energy is collected directly, 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 of the optical system (including the lighting system and the imaging 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 inspection light on the pupil plane to form a calibration image, the polarization transmittance can be measured at the pupil plane, which facilitates the selection of key areas for polarization transmittance calibration and analysis in 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 the intensity information, the intensity distribution information can also be collected. When the polarization transmittance changes, it is convenient to determine the cause of the change, such as the overall transmittance change or the local transmittance change.

[0082] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0083] refer to Figure 1 , Figure 1 An optical path diagram of an optical calibration system provided in an embodiment of the application, the optical calibration system is used for a dark field wafer detection device, and the optical calibration system includes:

[0084] The lighting system 11 is used to provide an initial lighting beam;

[0085] A polarizing module 12, the polarizing module 12 is used to apply polarization modulation to the initial illumination beam to form a polarized illumination beam;

[0086] An imaging system 13, the imaging system 13 is used to collect the polarized illumination light beam after being scattered by the target part 14 to form a detection light;

[0087] A polarization analyzer module 15, which is used to perform polarization screening on the detection light;

[0088] A pupil 16, which is located at the light exit side of the polarization analyzer module 15 and at the pupil plane of the imaging system 13; optionally, the pupil 16 may be a device such as a stop or an aperture;

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

[0090] In the embodiment of the present application, a pupil is provided on the light exit side of the imaging system, and 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 based on the detection light after passing through the scattered field. In the present application, at the position of the pupil plane of the imaging system 13, the scattered light will be spatially separated, and the calibration detection module 17 can image the system pupil plane, and then obtain the intensity distribution diagram of the pupil plane. The present application can control the polarization condition through the polarization analysis module 15, and based on the obtained calibration image, the polarization transmittance of the illumination light path to be measured relative to the scattered field can be accurately measured and calibrated.

[0091] Based on the above description, it can be known that the technical solution of the embodiment of the present application is based on the formation of a calibration image by the detection light of the optical system (including the lighting system 11 and the imaging system 13) after being scattered by the target part 14. Therefore, the calibration image can calibrate the polarization transmittance of the light after passing through the scattered field. This solution can calibrate the polarization transmittance based on the detection light of the detection camera entering the calibration detection module 17. Therefore, the calibration of the polarization transmittance of the optical system as a wafer detection equipment is more accurate, and the polarization transmittance after passing through the scattered field can be calibrated more precisely.

[0092] refer to Figure 2 , Figure 2 It is the different intensity images formed by the calibration detection module in the optical calibration system under the set pupil plane and the same polarization state. Under the set pupil plane and the same polarization state, if there is no abnormality in the optical system of the wafer detection equipment, the image formed by the calibration detection module is as follows: Figure 2 As shown in Figure (a), the intensity distribution of the entire image area is relatively uniform.

[0093] In the embodiment of the present application, the calibration image is formed by collecting the detection light through the pupil plane, and the pupil plane is used as the sampling intensity information of the detection camera in the calibration detection module 17, so as to achieve the following technical effects:

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

[0095] In addition, the polarization distribution of the optical system in the wafer inspection equipment is different within the aperture range, especially the polarization states in the middle and at the edge are different. By collecting the inspection light through the pupil plane to form a calibration image, the polarization transmittance can be measured at the pupil plane, which is convenient for selecting key areas for polarization transmittance calibration and analysis during subsequent data processing. Figure 2 As shown in Figure (b), the calibration image can be partitioned by dashed circles and / or dashed lines. It can be seen that there is a difference in grayscale values ​​between the outer and inner areas of the dashed circle, reflecting the difference in polarization transmittance at different partition positions. In some scenarios, the difference in polarization transmittance at the pupil plane will also be reflected in different directions. At this time, the difference in polarization transmittance at different directions can be reflected by multiple fan-shaped areas divided by the dashed line passing through the center of the circle.

[0096] Moreover, by collecting 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 determine 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 changes in the overall polarization transmittance or local polarization transmittance, which is reflected in the calibration image as a change in the grayscale value relative to Figure 2 Figure (a) in the figure has changed.

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

[0099] like Figure 2 As shown in Figure (d), when the wafer inspection equipment works for a long time in a specific inspection scenario, the scattered light produces diffraction orders at fixed positions in the imaging system. This diffraction order causes irreversible damage to the coating of some optical elements in the optical system. This damage will manifest as a decrease in polarization transmittance and will be visible in the grayscale image of the pupil plane.

[0100] In the example 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 part 14 is a wafer to be inspected, and the lighting system 11, the polarizing module 12, the imaging system 13, the polarizing module 15 and the pupil 16 are used to test the wafer to be inspected to determine whether it has defects. In the polarization transmittance calibration mode, the target part 14 is a standard film, and the lighting system 11, the polarizing module 12, the imaging system 13, the polarizing module 15 and the pupil 16 are used to determine the polarization transmittance after passing through the scattered field based on the standard film. Figure 1 This is the optical path diagram in polarization transmittance calibration mode.

[0101] like Figure 1 As shown, the calibration detection module 17 includes: a cut-in reflector 171, a pupil imaging mirror 172 and a first camera 173. The cut-in reflector 171 can be movably placed in the optical calibration system. Figure 1 As shown by the hollow arrow, the cut-in reflector 171 is used to be placed on the light exit 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 surface position of the first camera 173; the first camera 173 serves as a detection camera for 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 is a light path diagram of the optical calibration system in wafer detection mode. In wafer detection mode, the target part 14 is a wafer to be detected. Figure 3 As shown by the hollow arrow, the cut-in reflector 171 is used to be placed outside the illumination 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 detection module 18 which has the same optical axis as the imaging system 13. The wafer detection module 18 is used to form a defect detection image based on the detection light that can characterize the defect information of the wafer to be detected.

[0103] Optionally, the cut-in reflector 171 is mounted on a movable part, which is not shown in the optical path system provided in this application. The movable part can drive the cut-in reflector 171 to move horizontally or to rotate; the movable part is used to drive the cut-in reflector 171 to be placed on the light exit side of the pupil 16, or to drive the cut-in reflector 171 to be placed outside the illumination area of ​​the light exiting the pupil 16.

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

[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 movable and adjustable cut-in reflector 171, the error in its position may cause a difference in reflection effect. In the embodiment of the present application, the wafer detection module 18 is set to share the same optical axis with the imaging system 13, and the first optical axis L1 and the second optical axis L2 are perpendicular, so that the lighting of the wafer detection module 18 does not pass through the cut-in reflector 171, so as to avoid the above-mentioned difference in reflection effect affecting the detection effect of wafer defects, so as to ensure the accuracy of wafer defect detection. The wafer detection module 18 includes a second camera for imaging based on detection light.

[0106] In other embodiments, when the placement of the cut-in reflector 171 is controlled with high precision, the calibration detection module 17 can also be set to share the same optical axis with the imaging system 13, that is, the first optical axis L1 and the second optical axis L2 coincide, and the optical axis of the wafer detection module 18 is perpendicular to the first optical axis L1. In this way, in the wafer detection mode, the cut-in reflector 171 is placed on the light exit 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 that can characterize the defect information of the wafer to be detected based on the detection light. In the polarization transmittance calibration mode, the cut-in reflector 171 is placed outside the irradiation area of ​​the exit light of 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 share the same optical axis with the imaging system 13, so that the first camera forms a calibration image.

[0107] refer to Figure 4 , Figure 4 Another optical path diagram of an optical calibration system provided in an embodiment of the present application, based on any of the above implementations, Figure 4 The optical calibration system shown also includes: a host computer 19 connected to the calibration detection module 17, and 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 a built-in image processing algorithm.

[0108] Optionally, the host computer 19 is used to determine the polarization transmittance corresponding to the overall area of ​​the calibration image based on the overall grayscale data of the calibration image; or, the host computer 19 is used to divide the calibration image into multiple sub-areas, and determine the polarization transmittance corresponding to the sub-area based on the grayscale data of the sub-area, or the host computer 19 is used to determine the polarization transmittance corresponding to the overall area of ​​the calibration image based on the overall grayscale data of the calibration image, and is also used to divide the calibration image into multiple sub-areas, and determine the polarization transmittance corresponding to the sub-area based on the grayscale data of the sub-area.

[0109] In the optical calibration system provided in the embodiment of the present application, an initial illumination beam is provided by the illumination system 11, and a polarized illumination beam can be formed after polarization modulation is applied to the initial illumination beam by the polarizing module 12. The polarized illumination beam is obliquely incident on the surface of the target part 14 based on the set inclination angle. As described above, when used to calibrate the polarization transmittance, the target part 14 is a standard piece with a set roughness (generally in the order of a few nanometers to more than ten nanometers) so that the scattering intensity passing through the standard piece meets the system detection requirements. After the detection light formed by the scattering of the standard piece passes through the imaging system 13, it is then screened by the polarization of the polarization analyzer module 15, and the light that meets the polarization analyzer condition is reflected to the pupil imaging mirror 172 through a cut-in reflector 171, 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, which can be used to calibrate the polarization transmittance of the light after scattering by the standard piece.

[0110] Based on the optical calibration system provided in the above embodiment, another embodiment of the present application further provides an optical calibration method for the optical calibration system. The method can be as follows: Figure 5 shown.

[0111] refer to Figure 5 , Figure 5 A schematic diagram of a flow chart of an optical calibration method provided in an embodiment of the present application, the optical calibration method comprising:

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

[0113] Step S12: After the polarized illumination light beam having the target polarization state is formed by the polarizing module 12, the polarization state of the polarizing module 15 is adjusted to match the target polarization state.

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

[0115] Based on the optical calibration system provided in the above embodiment, the following can be achieved: Figure 5 The optical calibration method shown can accurately calibrate the polarization transmittance after passing through the scattered field.

[0116] As described above, based on the optical calibration system provided in the embodiment of the present application, the optical calibration method is to directly collect and image the scattered light entering the detection camera. The collected light already includes the influence of the entire optical system (illumination system 11 and imaging system 13) in the dark field image detection device on the polarization state, so the calibration of the polarization transmittance of the optical system is more accurate.

[0117] In addition, the optical calibration method is that after the polarized illumination light beam is scattered by the object surface of the target part 14, the scattered light (the detection light formed by the scattering of the target part 14) is received by the imaging system 13, and the intensity information of the scattered light is sampled at a set position using the first camera 173 in the calibration detection module 17. The intensity information is represented by the grayscale value of the first camera 173. By controlling the polarization analysis conditions in front of the pupil, 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 inspection device, which has a wafer inspection mode and a polarization transmittance calibration mode; the calibration inspection module 17 includes: a cutting-in reflector 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, such as Figure 1 As shown, the cut-in reflector 171 is placed on the light exit side of the pupil 16 to reflect the detection light passing through the pupil 16 to the pupil imaging mirror 172, and the collected detection light is imaged to the target surface position of the first camera 173 by the pupil imaging mirror 172, and the detection light is collected by the first camera 173 to form a calibration image.

[0120] When performing polarization transmittance calibration based on the optical calibration method, in wafer inspection mode, such as Figure 3 As shown, the cut-in reflector 171 is placed outside the illumination 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 detection module 18 which has the same optical axis as the imaging system 13, so that the wafer detection module 18 forms a defect detection image which can characterize the defect information of the wafer to be detected based on the detection light.

[0121] refer to Figure 6 , Figure 6 A flow chart of a method for calibrating the polarization state of a polarizing module provided in an embodiment of the present application is provided. The method for calibrating the polarization state of the polarizing module 12 includes:

[0122] Step S21: after adjusting the polarization analyzer module 15 to the non-polarization analyzer state, the background image under the condition of no initial illumination beam illumination is collected by the calibration detection module 17;

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

[0124] based on Figure 6 The method shown can calibrate the polarization state of the polarization module 12. When the optical system is used to perform actual inspection on the wafer, if the wafer of different material and roughness is replaced, the wafer defect inspection result can be corrected based on the calibration result to improve the accuracy and precision of wafer defect inspection.

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

[0126] refer to Figure 7 , Figure 7 A schematic flow chart of another optical calibration method provided in an embodiment of the present application, based on the above implementation, Figure 7 The optical calibration method also includes:

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

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

[0129] Optionally, in step S14, the polarization transmittance is determined based on the calibration image, including: 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 dividing the calibration image into multiple sub-areas, and determining the polarization transmittance corresponding to the sub-area based on the grayscale data of the sub-area.

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

[0131] The optical calibration method provided in the embodiment of the present application is further described below in combination with the optical calibration system provided in the above embodiment. The optical calibration method includes:

[0132] In the first step, the illumination system 11 can use a deep ultraviolet coherent light source for illumination, and adopts an oblique-incident dark-field illumination method. The light spot of the polarized illumination beam formed by the polarizing module 12 is illuminated on a standard sheet with a set roughness, so that the scattering intensity meets the detection requirements.

[0133] The second step is, Figure 1 As shown, the cut-in reflector 171 is placed at a set position on the light exit side of the pupil 16, and the cut-in reflector 171 is located in the light path between the pupil plane and the pupil imaging mirror 172. The polarization analyzer module 15 is adjusted to empty so that it is in a non-polarization analyzer 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 and fourth steps, the polarization state of the polarization module 12 can be calibrated.

[0135] The third step is to close the shutter in the lighting system 11 so that the lighting system 11 does not emit the initial lighting beam. At this time, the first camera 173 can capture the background image under the no-lighting condition to obtain the background intensity. Figure 8 As shown in Figure (d).

[0136] The fourth step is to open the shutter in the lighting system so that the lighting system emits an initial lighting beam, so that the calibration detection module 17 can use the detection light intensity under normal lighting conditions. In this step, the polarizing module 12 is rotated to find the first polarization position corresponding to the first camera 173 with the maximum photosensitivity. Based on the polarization incidence condition, the initial illumination light is polarized light. At the first polarization position, since it has the maximum photosensitivity, the light intensity of the scattered field is the largest at this time, and the grayscale value in the calibration image is the largest. Therefore, at this position, the polarization of the polarizing module 12 is consistent with that of the initial illumination beam. The calibration polarizing module 12 now has P polarization, and the emitted polarized illumination beam has P polarization. Among them, the calibration image corresponding to P polarization is as follows: Figure 8 As shown in Figure (a) in the figure. In the fifth step, after the P polarization calibration of the polarizing module 12 is completed, the first polarization position corresponding to the polarizing module 12 is confirmed. On this basis, other polarization states can be adjusted according to the quantitative angle position. Then, the pupil plane grayscale value is collected by the first camera 173 under other polarization states to achieve the purpose of calibrating the polarization transmittance of these polarization states. For example, when the polarizing module 12 is rotated to the second polarization position, the following can be obtained: Figure 8 The S-polarized calibration image shown in FIG. (c) is rotated to the third polarization position by rotating the polarizing module 12 to obtain the following Figure 8 (b) shows the calibration image of circular polarization. Compared with P polarization, the light intensity of the scattered field under S polarization is the smallest, and the image grayscale value in the calibration image is the smallest, while the scattering field intensity of circular polarization is between the scattering field intensities corresponding to P polarization and S polarization, so the grayscale value of the corresponding calibration image is also between the maximum image grayscale value and the minimum image grayscale value.

[0137] The difference between the grayscale value of the P-polarized image and the grayscale value of the background image can be used as the relative grayscale value of the P-polarized image, and the relative grayscale value of the P-polarized image is set to 1. Based on the relative grayscale value of the P-polarized image, the corresponding relative grayscale values ​​under the circular polarization and S-polarized image can be obtained. The ratio of the relative grayscale values ​​of the circular polarization and the P-polarized image, and the ratio of the relative grayscale values ​​of the S-polarized image and the P-polarized image are calculated. The two ratios are generally determined by the roughness and material of the scattering surface. After the calibration of the polarization state of the polarizing module 12 is completed, when the surface defects of the wafer are actually monitored, the defect detection results of wafers of different materials and roughness need to be corrected based on the above ratios to improve the defect detection precision and accuracy.

[0138] The sixth step is to further calibrate the polarization transmittance of the analyzer module 15 in different analyzer states after completing the calibration of the polarization state of the polarizing module 12. In this step, when the polarizing module 12 is in the target polarization state, the analyzer state of the analyzer module 15 is switched to correspond to the target polarization state, and the analyzer module 15 is in the analyzer state adapted to the polarizing module 12, and the calibration images under different target polarization states are respectively adopted by the first camera 173. The target polarization state includes but is not limited to P polarization and S polarization. If the polarizing module 12 is in P polarization, the target polarization state is P polarization, and correspondingly, the analyzer module 15 is in the P analyzer state, and if the polarizing module 12 is in S polarization, the target polarization state is S polarization, and correspondingly, the analyzer module 15 is in the S analyzer state. In the process of calibrating the polarization transmittance of the analyzer module 15 in different analyzer states, the first camera 173 is used to obtain the calibration images corresponding to the analyzer module 15 in different analyzer states to record the grayscale value.

[0139] When the polarization analyzer module 15 is in the non-polarization analyzer state, if the polarization module 12 is in the P polarization state, the calibration image is set to have an initial P polarization image grayscale value P0, and if the polarization module 12 is in the S polarization state, the calibration image is set to have an initial S polarization image grayscale value S0. When the polarization analyzer module 15 is in the polarization analyzer state, if the polarization module 12 is in the P polarization state, the polarization analyzer module 15 is in the P polarization analyzer state, the calibration image is set to have 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, the corresponding calibration image has the first S polarization image gray value S1, and the transmittance is T PS If the polarizing module 12 is in S polarization, the polarization analyzing module 15 is in S polarization state, the calibration image is set to have a second S polarization image gray value S2, the transmittance is T SS , or the polarization module is in the P polarization state, the corresponding calibration image has a second P polarization image gray value P2, and the transmittance is T SP . Assuming the gray value of the background image is A, the method for calculating the polarization transmittance includes calculating T PP , T PS , T SS and T SP , T PP , T PS , T SS and T SP The calculation method is as follows:

[0140] ;

[0141] ;

[0142] ;

[0143] .

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

[0145] In the above calibration, the overall grayscale data of the calibration image is collected as the calibration parameter. In some scenarios, it is necessary to pay attention to the transmittance change of the local area. Based on this, the calibration image can also be divided into multiple sub-areas in the embodiment of the present application. Based on the division of the sub-areas, the polarization transmittance of the local area that needs attention is calibrated. Figure 2 In the middle (b) figure, the sub-region is divided. Based on the dotted circle, the calibration image is divided into a circular sub-region located inside the dotted circle and a circular ring sub-region located outside the dotted circle. Based on the vertically intersecting dotted straight lines, the calibration image is divided into four sector-shaped sub-regions corresponding to four different orientations. Based on the divided sub-regions, the image grayscale values ​​corresponding to the set sub-region in the polarization detection state and the non-detection state can be obtained in the same way as in the fifth and sixth steps above. Based on the same calculation principle, TP and TS are calculated respectively to realize 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 further provides a dark field pattern detection device. In combination with 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] The lighting system 11 is used to provide an initial lighting beam;

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

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

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

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

[0153] The calibration detection module 17, 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 used 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;

[0154] In the wafer inspection mode, the wafer inspection module 18 is used to form a defect inspection image capable of representing defect information of the wafer to be inspected based on the inspection light.

[0155] Optionally, the wafer may be a patterned wafer or a non-patterned wafer, and the embodiment of the present application does not limit the type of wafer to be inspected.

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

[0157] In the specification of this application, each embodiment is described in a progressive, parallel, or progressive and parallel manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. The embodiments provided in the embodiments of this application can be combined with each other if there is no contradiction.

[0158] It should be noted that in the description of the present application, it should be understood that the description of the drawings and embodiments is illustrative rather than restrictive. The same reference numerals throughout the embodiments of the specification identify the same structure. In addition, for the sake of understanding and ease of description, the drawings may exaggerate the thickness of some layers, films, panels, regions, etc. It is also understood that when an element such as a layer, film, region, or substrate is referred to as "on" another element, the element may be directly on the other element or there may be an intermediate element. In addition, "on" refers to positioning an element on or below another element, but does not essentially refer to positioning on the upper side of another element according to the direction of gravity.

[0159] The terms "upper", "lower", "top", "bottom", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are 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 therefore cannot be understood as limiting the present application. When a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0160] It should also be noted that, in this article, relational terms such as first and second, etc. 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 terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the article or device including 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 may 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 the embodiments shown herein, but will conform to 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 beam to form a polarized illumination 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 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.

2. The optical calibration system according to claim 1, characterized in that: The dark field wafer inspection device has a wafer inspection mode and a polarization transmittance calibration mode; The calibration detection module comprises: an incision reflector, a pupil imaging mirror and a first camera; wherein the incision reflector is movably placed in the optical calibration system; the incision reflector is used to be placed on the light exit 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 the calibration image based on the incident detection light; Among them, in the wafer detection 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 detection module that has a common optical axis with the imaging system, and the wafer detection 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; A calibration image corresponding to the target polarization state is acquired through the calibration detection module; the calibration image can at least characterize the polarization transmittance of the polarized illumination light beam after scattering.

7. The optical calibration method according to claim 6, characterized in that: 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; The calibration detection module includes: a cut-in reflector, a pupil imaging mirror and a first camera; the cut-in reflector can be 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, the collected detection light is imaged to the target surface position of the first camera by the pupil imaging mirror, and the detection light is collected by the first camera to form the calibration image; 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 beam to form a polarized illumination 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