A bright and dark field detection device and method

Abstract

The present invention relates to the field of optical detection technologies, and particularly to a bright and dark field detection device and method. After the first illumination light emitted by the bright field light source is modulated by the illumination modulation component, it is respectively guided to irradiate the surface of the sample to be measured together with the second illumination light emitted by the dark field light source. The first illumination light is reflected by the sample to be measured to form bright field signal light, and the second illumination light is scattered by the sample to be measured to form dark field signal light. The bright field signal light and the dark field signal light are transmitted along a common optical path and are spatially separated from each other. The objective lens adapted to the illumination modulation component receives and microscopically magnifies the bright field signal light and the dark field signal light. The imaging component receives the bright field signal light and the dark field signal light and performs bright field imaging and dark field imaging. The present invention realizes simultaneous imaging detection of bright and dark fields through the bright and dark field common optical path and split field of view design. In addition, by setting the illumination modulation component, the reflection phenomenon of the illumination light occurring outside the exit pupil plane of the objective lens is suppressed, and the interference of stray light on imaging is eliminated.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and particularly relates to a bright and dark field detection device and method. Background Art

[0002] Pollution inevitably occurring during the semiconductor chip processing and defects caused by manufacturing errors are important reasons for chip failure. Conducting wafer defect detection during the semiconductor manufacturing process can improve the yield rate and obtain higher profits. Among the existing wafer defect detection methods, the method based on optical imaging has the advantages of being fast and non-contact, and is the most commonly used means for wafer detection.

[0003] The detection speed and detection accuracy are important parameters for wafer defect detection. The detection accuracy refers to the minimum size of defects that can be detected. Increasing the magnification can obtain a smaller optical resolution and improve the detection accuracy, but it also reduces the detection speed at the same time. Bright field detection is limited by the diffraction limit, and the minimum detectable defect is only the radius of the Airy disk; while dark field detection is based on Rayleigh scattering or Mie scattering of small particles. As long as the scattering signal of small size defects can be detected, the detection sensitivity can be improved. Therefore, in order to improve the detection sensitivity of the detection device, a dark field detection device is usually configured in the bright field detection device to construct a bright and dark field detection device. Therefore, the scheme of simultaneous scanning of bright field and dark field can improve both the detection accuracy and the detection speed.

[0004] In the bright and dark field detection device, considering that there are many types of possible defects on the chip, and the bright field imaging and dark field imaging have different resolution capabilities for different types of defects, then the detection method of simultaneously using bright field imaging and dark field imaging will improve the detection ability of these defects. At this time, when simultaneously scanning the sample to be measured in bright field and dark field, in addition to preventing crosstalk through reasonable field-of-view offset design, it is also often accompanied by the influence of stray light, resulting in the technical problem of reduced signal-to-noise ratio of optical imaging. Summary of the Invention

[0005] In view of this, in order to reduce the interference of stray light on imaging in the bright and dark field detection device, the present invention provides a bright and dark field detection device and method, which adopt a common optical path design for bright field and dark field, realize simultaneous imaging of bright field and dark field by setting different illumination areas for bright field and dark field, and then perform imaging through the imaging component, so that bright field and dark field are scanned simultaneously; at the same time, a lighting modulation component is set to change the size of the illumination beam to match the exit pupil diameter of the objective lens, significantly suppressing the reflection phenomenon of the illumination light outside the exit pupil plane of the objective lens, avoiding the interference of stray light on imaging by eliminating the stray light formed by the reflection phenomenon, thereby obtaining a good dark field imaging effect and improving the defect detection ability in dark field; in addition, the lighting modulation component can also adjust the angular spectrum frequency of bright field illumination, realize illumination with multiple angular spectrum frequencies, reduce the brightness of the background pattern of the sample to be measured, minimize stray light as much as possible, highlight defects, and improve the contrast of defects.

[0006] To achieve the above object, the technical solution of the present invention is implemented as follows:

[0007] A bright and dark field detection device includes: a bright field light source that emits a first illumination light; an illumination modulation component that modulates the first illumination light; a dark field light source that emits a second illumination light; the first illumination light and the second illumination light are respectively guided to irradiate the surface of a sample to be measured. The first illumination light is reflected by the sample to be measured to form a bright field signal light, and the second illumination light is scattered by the sample to be measured to form a dark field signal light; the bright field signal light and the dark field signal light are transmitted along a common optical path and are spatially separated from each other; an objective lens that receives the bright field signal light and the dark field signal light and respectively performs microscopic imaging, and the illumination modulation component is adapted to the exit pupil diameter of the objective lens and can suppress the reflection phenomenon of the first illumination light occurring outside the exit pupil plane of the objective lens; an imaging component that receives the bright field signal light and the dark field signal light emitted from the objective lens and performs bright field imaging and dark field imaging.

[0008] In some embodiments, the illumination modulation component includes a front relay lens group, a spatial filter group, and a rear relay lens group; wherein, the spatial filter group is located at the Fourier plane between the front relay lens group and the rear relay lens group; the exit aperture of the spatial filter group matches the exit pupil diameter of the objective lens, and the spatial filter group is conjugate to the exit pupil plane of the objective lens.

[0009] In some embodiments, the spatial filter group includes a spatial filter and a motorized turntable provided on the spatial filter. A plurality of light exit holes with different exit apertures are provided on the motorized turntable, and the light exit holes can be switched so that the exit aperture matches the exit pupil diameter of the objective lens.

[0010] In some embodiments, the spatial filter group includes a spatial filter and a motorized diaphragm provided on the spatial filter. The motorized diaphragm can be adjusted so that the exit aperture matches the exit pupil diameter of the objective lens.

[0011] In some embodiments, the illumination modulation component further includes a plurality of filter sheets with different colors, and the colors of the filter sheets are different from the background color of the sample to be measured.

[0012] In some embodiments, the objective lens includes a plurality of sub-objective lenses with different exit pupil diameters; the first illumination light is incident on the surface of the sample to be measured through the sub-objective lens, and the bright field signal light and the dark field signal light are respectively incident on the imaging component from both sides of the optical axis of the sub-objective lens; the bright field signal light and the dark field signal light are transmitted along a common optical path between the sub-objective lens participating in the optical path transmission and the imaging component and are spatially separated from each other; the sub-objective lens participating in the optical path transmission can be switched, and the illumination modulation component is adapted to the exit pupil diameter of the sub-objective lens participating in the optical path transmission.

[0013] In some embodiments, a beam splitter element is further provided between the illumination modulation component and the objective lens; the first illumination light enters the objective lens after passing through the beam splitter element; both the bright-field signal light and the dark-field signal light sequentially pass through the objective lens and the beam splitter element and are incident on the imaging component; the bright-field signal light and the dark-field signal light are transmitted in a common optical path between the objective lens and the beam splitter element and between the beam splitter element and the imaging component.

[0014] In some embodiments, an illumination lens group is further provided between the illumination modulation component and the objective lens; the first illumination light emitted by the illumination modulation component is irradiated onto the surface of the sample to be measured after sequentially passing through the illumination lens group and the objective lens; the exit aperture of the spatial filter group, the exit pupil diameter of the objective lens, the focal length of the illumination lens group, and the focal length of the front relay lens group or the rear relay lens group satisfy the following relationship:

[0015] D 瞳 / D 滤波 =F 照明 / F 中继 ;

[0016] wherein, D 瞳 represents the exit pupil diameter of the objective lens, D 滤波 represents the exit aperture of the spatial filter group, F 照明 represents the focal length of the illumination lens group, F 中继 represents the focal length of the front relay lens group or the rear relay lens group.

[0017] In some embodiments, an imaging lens group is further provided between the beam splitter element and the imaging component; the bright-field signal light and the dark-field signal light emitted from the beam splitter element are incident on the imaging component after passing through the imaging lens group, and the bright-field signal light and the dark-field signal are transmitted in a common optical path between the beam splitter element and the imaging lens group.

[0018] In some embodiments, a focus detection component is further provided between the beam splitter element and the objective lens; the focus detection component includes: a dichroic mirror disposed between the beam splitter element and the objective lens; an automatic focus detection module for emitting a detection light; the detection light is irradiated onto the surface of the sample to be measured after passing through the dichroic mirror and the objective lens and forms a focus detection light after being reflected on the surface of the sample to be measured, the focus detection light reaches the automatic focus detection module along the original optical path, and the automatic focus detection module is further used to determine the position of the sample to be measured relative to the front focal plane of the objective lens by using the focus detection light.

[0019] In some embodiments, the imaging component includes an optical separation element, a bright-field camera, and a dark-field camera; wherein, the optical separation element collects the bright-field signal light and the dark-field signal light and performs optical path separation, so that the dark-field signal light and the bright-field signal light respectively enter the dark-field camera and the bright-field camera to perform dark-field imaging and bright-field imaging.

[0020] In some embodiments, the optical separation element includes a first reflecting surface and a second reflecting surface; the first reflecting surface is configured to receive bright-field signal light and reflect the bright-field signal light into the bright-field camera; the second reflecting surface is configured to receive dark-field signal light and reflect the dark-field signal light into the dark-field camera.

[0021] A bright and dark field detection method includes:

[0022] Controlling a bright-field light source to emit first illumination light to an illumination modulation component;

[0023] According to the exit pupil diameter of the objective lens, controlling the illumination modulation component to modulate the first illumination light;

[0024] The modulated first illumination light is irradiated onto a sample to be measured through the objective lens, and controlling a dark-field light source to emit second illumination light to the sample to be measured;

[0025] The first illumination light is reflected by the sample to be measured to form bright-field signal light, and the second illumination light is scattered by the sample to be measured to form dark-field signal light;

[0026] The bright-field signal light and the dark-field signal light are transmitted along a common optical path through the objective lens and are spatially separated from each other, and the bright-field signal light and the dark-field signal light are transmitted to an imaging component to perform bright-field imaging and dark-field imaging respectively.

[0027] In some embodiments, an illumination lens group is further provided between the illumination modulation component and the objective lens; the illumination modulation component includes a front relay lens group and a rear relay lens group, and a spatial filtering group located at the Fourier plane between the front relay lens group and the rear relay lens group;

[0028] In the process of controlling the illumination modulation component to modulate the first illumination light according to the exit pupil diameter of the objective lens:

[0029] Adjust the light output aperture of the spatial filtering group according to the exit pupil diameter of the objective lens, so that the light output aperture of the spatial filtering group, the exit pupil diameter of the objective lens, the focal length of the illumination lens group, and the focal length of the front relay lens group or the rear relay lens group satisfy the following corresponding relationship:

[0030] D 瞳 / D 滤波 =F 照明 / F 中继 ;

[0031] Wherein, D_pupil represents the exit pupil diameter of the objective lens, D_filter represents the light output aperture of the spatial filtering group, F_illumination represents the focal length of the illumination lens group, and F_relay represents the focal length of the front relay lens group or the rear relay lens group.

[0032] In some embodiments, the spatial filtering group includes a spatial filter and an electric turntable provided on the spatial filter, and a plurality of light output holes with different light output apertures are provided on the electric turntable;

[0033] In the process of adjusting the light output aperture of the spatial filter group according to the exit pupil diameter of the objective lens, control the rotation of the electric turntable so that the light output aperture of the light output hole and the exit pupil diameter of the objective lens satisfy the corresponding relationship.

[0034] In some embodiments, the spatial filter group includes a spatial filter and an electric diaphragm arranged on the spatial filter;

[0035] In the process of adjusting the light output aperture of the spatial filter group according to the exit pupil diameter of the objective lens, control the size of the light output aperture of the electric diaphragm so that the light output aperture of the electric diaphragm and the exit pupil diameter of the objective lens satisfy the corresponding relationship.

[0036] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0037] (1) In the bright and dark field detection device and method of the present invention, through the common optical path design of the bright field and the dark field, the illumination areas of the bright field and the dark field are different to achieve simultaneous imaging of the bright and dark fields, and then imaging is performed through the imaging component, so that the bright field and the dark field are scanned simultaneously; setting the illumination modulation component can change the size of the illumination beam to match the exit pupil diameter of the objective lens, significantly suppressing the reflection phenomenon of the illumination light on the periphery of the exit pupil plane of the objective lens, avoiding the interference of the imaging by the stray light formed by eliminating the reflection phenomenon, thereby obtaining a good dark field imaging effect and improving the defect detection ability in the dark field; in addition, the set illumination modulation component can adjust the angular spectrum frequency of the bright field illumination, realize illumination with multiple angular spectrum frequencies, reduce the brightness of the background pattern of the sample to be measured, minimize the stray light as much as possible, highlight the defects, and improve the contrast of the defects;

[0038] (2) In the bright and dark field detection device and method of the present invention, the illumination modulation component includes one or more of an illumination optical path relay lens group, a spatial filter, and a filter; the spatial filter is conjugate to the exit pupil plane of the objective lens, and an electric turntable or an electric diaphragm that can change the light output hole is arranged on the spatial filter, so that the size of the illumination beam passing through the light output hole matches the exit pupil diameter of the objective lens, thereby eliminating the stray light formed by the reflection phenomenon on the periphery of the exit pupil plane of the objective lens, avoiding the interference of the imaging by the stray light, and thus obtaining a good dark field imaging effect and improving the defect detection ability in the dark field. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0040] Figure 1 is a schematic structural diagram of the bright and dark field detection device described in the embodiment of the present invention;

[0041] Figure 2Schematic diagram of stray light generation according to the embodiments of the present invention;

[0042] Figure 3 Schematic diagram of the electric turntable and the electric diaphragm according to the embodiments of the present invention;

[0043] Figure 4 Schematic flow chart of the bright and dark field detection method according to the embodiments of the present invention.

[0044] Explanation of reference numerals:

[0045] 1. Bright field light source; 2. Dark field light source; 3. Objective lens; 4. Sample to be measured; 5. Front relay lens group; 6. Spatial filtering group; 7. Rear relay lens group; 8. Field stop; 9. Illumination lens group; 10. Light exit hole; 11. Beam splitter element; 12. Reflecting mirror; 13. Imaging lens group; 14. Dichroic mirror; 15. Automatic focusing module; 16. Bright field camera; 17. Dark field camera; 18. First reflecting surface; 19. Second reflecting surface; 31. Exit pupil plane; 32. Periphery of the exit pupil plane. Detailed implementation manners

[0046] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention.

[0047] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0048] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "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 invention 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 limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0049] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0051] As Figure 1 shown, the bright and dark field detection device described in the embodiment of the present invention includes a bright field light source 1, a dark field light source 2, an illumination modulation component, an objective lens 3, and an imaging component. The bright field light source 1 emits a first illumination light, the dark field light source 2 emits a second illumination light, the illumination modulation component modulates the first illumination light, and the modulated first illumination light is reflected by the sample to be measured 4 to form a bright field signal light, and the second illumination light is scattered by the sample to be measured 4 to form a dark field signal light. The bright field signal light and the dark field signal are transmitted along a common optical path and are spatially separated during the propagation process. The objective lens 3 receives the bright field signal light and the dark field signal light and performs microscopic imaging respectively, and the imaging component receives the bright field signal light and the dark field signal light emitted by the objective lens 3, and performs bright field imaging and dark field imaging.

[0052] It should be noted that the illumination modulation component has an adjustable light passing aperture, and the light passing aperture can be adapted to the exit pupil diameter of the objective lens 3. This is because different magnifications of the objective lens 3 result in different pupil plane positions and exit pupil diameters of the objective lens 3. In order to ensure sufficient illumination, the illumination spot should match the exit pupil diameter of the objective lens 3. Without the illumination modulation component, when the objective lens 3 changes (i.e., the exit pupil diameter of the objective lens 3 changes), the beam size of the first illumination light may be larger than the exit pupil diameter of the objective lens 3, resulting in a situation where a part of the light irradiates on the exit pupil plane of the objective lens 3, and another part of the light irradiates on the periphery of the exit pupil plane of the objective lens 3, causing the light irradiating on the periphery of the exit pupil plane of the objective lens 3 to be reflected, thereby forming stray light, specifically as Figure 2 shown.

[0053] Since the bright field and the dark field are detected simultaneously and the bright field and the dark field share the same optical path, stray light will enter the imaging regions of the bright field and the dark field, resulting in an increase in detection noise, a decrease in the signal-to-noise ratio, and a reduction in detection accuracy; since the dark field imaging is particularly sensitive to the input amount of light, a small amount of stray light may cause distortion in the dark field imaging. Therefore, it is necessary to strictly limit the stray light from entering the imaging optical path of the dark field. Therefore, it is necessary to set an illumination modulation component for modulating the first illumination light before the objective lens 3 in the light propagation path, and it is necessary to ensure that the illumination modulation component is adapted to the exit pupil diameter of the objective lens 3.

[0054] It should be noted that the objective lens 3 has an entrance pupil plane and an exit pupil plane. Generally, the side facing the sample 4 to be measured is the entrance pupil plane, and the side opposite to the sample 4 to be measured is the exit pupil plane. In Figure 2 , 31 is the exit pupil plane of the objective lens 3. The first illumination light is allowed to enter the exit pupil plane 31 and exit from the entrance pupil plane of the objective lens 3 to the surface of the sample 4 to be measured. It can be understood that the exit pupil diameter of the objective lens 3 is the diameter of the exit pupil plane 31 of the objective lens 3. Figure 2 The periphery 32 of the exit pupil plane of the objective lens 3 in can be understood as a structural member for fixing the lens, which can reflect the light irradiated on the surface of the structural member. The reflected light is mixed into the transmission optical paths of the bright-field signal light and the dark-field signal light to form stray light. It can be understood that since the objective lens 3 uses a common optical path and split field-of-view transmission method for the bright-field signal light and the dark-field signal light, the first illumination light does not enter the entire exit pupil plane of the objective lens 3, but enters a partial exit pupil plane of the objective lens 3 and is located in the area on one side of the optical axis. This side area also allows the bright-field illumination light to exit; the other partial exit pupil plane of the objective lens 3 is located in the area on the other side of the optical axis, and this side area allows the dark-field illumination light to exit.

[0055] In a certain embodiment, it is preferable that the bright-field light source 1 and the dark-field light source 2 respectively emit continuous first illumination light and second illumination light. For example, a high-brightness LED light source is used to emit continuous illumination light.

[0056] In some embodiments, the illumination modulation component includes a front relay lens group 5, a spatial filtering group 6, and a rear relay lens group 7. The spatial filtering group 6 is located at the Fourier plane (i.e., the central focal plane of the front relay lens group 5 and the rear relay lens group 7) between the front relay lens group 5 and the rear relay lens group 7. The exit aperture of the spatial filtering group 6 matches the exit pupil diameter of the objective lens 3, and the spatial filtering group 6 is conjugate to the exit pupil plane of the objective lens 3.

[0057] In a certain embodiment, a field stop 8 is provided on the light-emitting side of the rear relay lens group 7. After the first illumination light completes the modulation of the beam size (or beam diameter) in the illumination modulation component, it is then subjected to field modulation by the field stop 8; the front relay lens group 5 and the rear relay lens group 7 are symmetrically placed with the same lenses, and the focal lengths of the two relay lens groups range from 50 to 150 mm. The exit surfaces of the front relay lens group 5, the spatial filtering group 6, the rear relay lens group 7, the field stop 8, and the bright-field light source 1 form a 4F system.

[0058] In some embodiments, an illumination lens group 9 is further provided between the illumination modulation component and the objective lens 3. The first illumination light emitted by the illumination modulation component is sequentially irradiated onto the surface of the sample 4 to be measured after passing through the illumination lens group 9 and the objective lens 3. The exit aperture of the spatial filtering group 6, the exit pupil diameter of the objective lens 3, the focal length of the illumination lens group 9, and the focal length of the front relay lens group 5 or the rear relay lens group 7 satisfy the following relationship:

[0059] D 瞳 / D滤波 = F 照明 / F 中继 。

[0060] Among them, D 瞳 represents the exit pupil diameter of the objective lens 3, and D 滤波 represents the light output aperture of the spatial filter group 6, and F 照明 represents the focal length of the illumination lens group 9, and F 中继 represents the focal length of the front relay lens group 5 or the rear relay lens group 7. The exit pupil diameter D 瞳 is related to the focal length f and numerical aperture NA of the objective lens 3, that is:

[0061] D 瞳 = 2 × f × NA.

[0062] In actual use, the focal lengths of the illumination lens group 9, the front relay lens group 5 or the rear relay lens group 7 can be adjusted as needed, and the objective lens 3 with different exit pupil diameters can be selected, and the light output aperture of the spatial filter group 6 can be changed after calculation according to the above relationship.

[0063] In a certain embodiment, after comprehensively considering factors such as the space limitation of the entire bright and dark field detection device, the field of view limitation of the illumination system, and the aperture limitation of the illumination system, the preferred range of the focal length of the illumination lens group 9 is 150 - 250 mm. Taking the case where the focal length of the illumination lens group 9 is selected as 200 mm as an example, at this time, the focal lengths of the front relay lens group 5 and the rear relay lens group 7 are selected as 100 mm, then:

[0064] D 瞳 / D 滤波 = F 照明 / F 中继 = 200 / 100 = 2.

[0065] That is, it is determined that the exit pupil diameter D 瞳 of the objective lens 3 is twice the light output aperture D 滤波 of the spatial filter group 6.

[0066] In some embodiments, the objective lens 3 includes multiple sub-objective lenses with different exit pupil diameters. The first illumination light is incident on the surface of the sample to be measured 4 through the sub-objective lens, and the bright field signal light and the dark field signal light are incident on the imaging assembly on both sides of the optical axis of the sub-objective lens respectively. The bright field signal light and the dark field signal light are transmitted in a common optical path between the sub-objective lens and the imaging assembly participating in the optical path transmission, and are spatially separated from each other. The sub-objective lens participating in the optical path transmission can be switched, and the illumination modulation assembly is adapted to the exit pupil diameter of the sub-objective lens participating in the optical path transmission.

[0067] In one embodiment, the objective lens 3 includes sub-objective lenses with five magnifications of 1.5×, 2.5×, 5×, 10×, and 20×, and the corresponding exit pupil diameters are 16 mm, 24 mm, 20 mm, 18 mm, and 11 mm respectively. According to the above relationships, the magnification of the objective lens 3, the NA of the objective lens 3, and the exit pupil diameter D of the objective lens 3 can be obtained. 瞳 and the exit aperture D of the spatial filter group 6 滤波 As shown in Table 1:

[0068] Table 1 Related numerical table of the objective lens and the spatial filter group

[0069]

[0070] It can be understood that the exit pupil diameters of the objective lenses 3 with different magnifications are 16 mm, 24 mm, 20 mm, 18 mm, and 11 mm respectively. According to the ratio of the exit pupil diameter of the objective lens to the exit aperture of the spatial filter group 6 being 2, the exit apertures of the spatial filter group 6 can be calculated to be 8 mm, 12 mm, 10 mm, 9 mm, and 5.5 mm respectively. In actual use, according to the needs, the focal lengths of the front relay lens group 5, the rear relay lens group 7, and the illumination lens group 9 are adjusted, and the objective lens 3 with different exit pupil diameters is selected. Only by calculating according to the above formula and then changing the exit aperture of the spatial filter group 6 can it be achieved.

[0071] If there is no spatial filter group 6, in order to ensure illumination at each magnification, the diameter of the light spot illuminating on the exit pupil plane of the objective lens 3 should be at least 24 mm (taking the maximum case of 2.5×), and the exit aperture of the spatial filter group 6 is 12 mm; at this time, when the magnification of the objective lens 3 is switched to 20× (i.e., the exit pupil diameter is 11 mm), the illumination light spot diameter is larger than the exit pupil diameter of the objective lens (24 mm > 11 mm), resulting in stray light. When the spatial filter group 6 is used, referring to Table 1, by adjusting the exit aperture of the spatial filter group 6 to 5.5 mm, the light spot illuminating on the exit pupil plane of the objective lens 3 becomes 11 mm, just matching the exit pupil diameter of 20×, reducing stray light.

[0072] In some embodiments, the spatial filter group 6 includes a spatial filter, and an electric turntable or an electric diaphragm provided on the spatial filter. Since the aperture size of the spatial filter is related to the angular spectrum frequency of light propagation, and at the same time, it is necessary to achieve the matching between the spatial filter and the exit pupil diameter of the objective lens 3. Therefore, by providing an electric turntable or an electric diaphragm with an adjustable exit aperture on the spatial filter, the aperture size of the spatial filter is changed, and the exit pupil diameter of the objective lens 3 is matched by changing the beam size, avoiding the generation of stray light due to reflection of the beam outside the exit pupil plane of the objective lens.

[0073] In one embodiment, the electric turntable and the electric diaphragm are as Figure 3As shown. There are multiple light-emitting holes 10 with different light-emitting apertures on the electric turntable. The light-emitting holes 10 can be switched so that the light-emitting aperture matches the exit pupil diameter of the objective lens 3. Specifically, 5 light-emitting holes 10 with different light-emitting apertures can be arranged on the electric turntable, and the 5 light-emitting holes 10 are circumferentially and evenly arranged on the electric turntable. As shown in (a) of Figure 3 , when switching the objective lens 3, the motor drives the electric turntable to rotate to complete the switching of the light-emitting holes 10, and then complete the adjustment of the light-emitting aperture of the spatial filter. The electric diaphragm is as shown in (b) of Figure 3 . By electrically controlling the diameter of the light-emitting hole 10 on the electric diaphragm to change the size of the aperture, the light-emitting aperture of the spatial filter is made to match the exit pupil diameter of the objective lens 3.

[0074] In some embodiments, the illumination modulation component further includes multiple color filters of different colors, and the color of the color filter is different from the background color of the sample 4 to be measured. In a certain embodiment, when the background color is red, the color of the color filter is preferably blue, green or yellow, etc.

[0075] In some embodiments, a beam splitting element 11 is further provided between the illumination modulation component and the objective lens 3. The first illumination light enters the objective lens 3 after passing through the beam splitting element 11, and both the bright field signal light and the dark field signal light sequentially pass through the objective lens 3 and the beam splitting element 11 and are incident on the imaging component. The bright field signal light and the dark field signal light are transmitted in a common optical path between the objective lens 3 and the beam splitting element 11 and between the beam splitting element 11 and the imaging component.

[0076] In a certain embodiment, the beam splitting element 11 is a beam splitting prism and is arranged between the illumination lens group 9 and the objective lens 3. At this time, it can be obtained that the first illumination light emitted by the bright field light source 1 enters the illumination lens group 9 after being modulated by the illumination modulation component. The illumination lens group 9 projects the modulated first illumination light into the beam splitting element 11, and the beam splitting element 10 projects the first illumination light into the objective lens 3. To fold the optical path and reduce the volume of the device provided by the present invention, a reflecting mirror 12 for reflecting the first illumination light is provided between the beam splitting element 11 and the illumination lens group 9.

[0077] In some embodiments, an imaging lens group 13 is further provided between the beam splitting element 11 and the imaging component. The bright field signal light and the dark field signal light emitted from the beam splitting element 11 enter the imaging component after passing through the imaging lens group 13, and the bright field signal light and the dark field signal are transmitted in a common optical path between the beam splitting element 11 and the imaging lens group 13.

[0078] In some embodiments, a focus detection component is further disposed between the beam splitting element 11 and the objective lens 3. The focus detection component includes a dichroic mirror 14 and an automatic focus detection module 15. The dichroic mirror 14 is disposed between the beam splitting element 11 and the objective lens 3. The automatic focus detection module 15 is configured to emit a detection light, which is irradiated onto the surface of the sample 4 to be measured after passing through the dichroic mirror 14 and the objective lens 3, and a focus detection light is formed by reflection on the surface of the sample 4 to be measured. The focus detection light reaches the automatic focus detection module 15 along the original optical path, and the automatic focus detection module 15 is further configured to determine the position of the sample 4 to be measured relative to the front focal plane of the objective lens 3 by using the focus detection light.

[0079] In some embodiments, the imaging component includes an optical separation element, a bright field camera 16, and a dark field camera 17. Among them, the optical separation element collects the bright field signal light and the dark field signal light and performs optical path separation, so that the dark field signal light and the bright field signal light respectively enter the dark field camera 17 and the bright field camera 16 to perform dark field imaging and bright field imaging.

[0080] In some embodiments, the optical separation element includes a first reflection surface 18 and a second reflection surface 19. The first reflection surface 18 is configured to receive the bright field signal light and reflect the bright field signal light into the bright field camera 16; the second reflection surface 19 is configured to receive the dark field signal light and reflect the dark field signal light into the dark field camera 17.

[0081] Based on the provided bright and dark field detection device, the present invention further provides a bright and dark field detection method, which combines Figures 1 to 4 , and the method includes:

[0082] S1: Controlling the bright field light source to emit a first illumination light to the illumination modulation component.

[0083] S2: Controlling the illumination modulation component to modulate the first illumination light according to the exit pupil diameter of the objective lens.

[0084] In some embodiments, the light output aperture of the spatial filter group 6 in the illumination modulation component is adjusted according to the exit pupil diameter of the objective lens 3, so that the light output aperture of the spatial filter group 6, the exit pupil diameter of the objective lens 3, the focal length of the illumination lens group 9, and the focal lengths of the front relay lens group 5 and the rear relay lens group 7 satisfy the following corresponding relationship:

[0085] D 瞳 / D 滤波 =F 照明 / F 中继 .

[0086] In one embodiment, the spatial filtering group 6 includes a spatial filter and a motorized turntable disposed on the spatial filter. A plurality of light exit holes 10 with different light exit apertures are provided on the motorized turntable. At this time, the process of adjusting the light exit aperture of the spatial filtering group according to the exit pupil diameter of the objective lens 3 includes: controlling the rotation of the motorized turntable so that the light exit aperture of the light exit hole 10 satisfies a corresponding relationship with the exit pupil diameter of the objective lens 3.

[0087] In one embodiment, the spatial filtering group 6 includes a spatial filter and a motorized diaphragm. At this time, the process of adjusting the light exit aperture of the spatial filtering group according to the exit pupil diameter of the objective lens includes: controlling the aperture size of the light exit hole 10 of the motorized diaphragm so that the aperture of the light exit hole 10 of the motorized diaphragm satisfies a corresponding relationship with the exit pupil diameter of the objective lens 3.

[0088] S3: The modulated first illumination light is irradiated onto the sample 4 to be measured through the objective lens 3, and the dark field light source is controlled to emit second illumination light to the sample 4 to be measured.

[0089] S4: The first illumination light is reflected by the sample 4 to be measured to form a bright field signal light, and the second illumination light is scattered by the sample 4 to be measured to form a dark field signal light.

[0090] S5: The bright field signal light and the dark field signal light are transmitted along a common optical path through the objective lens 3 and are spatially separated from each other. The bright field signal light and the dark field signal light are transmitted to the imaging assembly to perform bright field imaging and dark field imaging respectively.

[0091] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added, or deleted. For example, the steps recited in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved. No limitation is made herein.

[0092] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A light and dark field detection device, characterized in that, Comprising: A bright-field light source that emits a first illumination light; An illumination modulation component that modulates the first illumination light; the illumination modulation component includes a spatial filtering group, a front relay lens group, and a rear relay lens group; A dark-field light source that emits a second illumination light; The first illumination light and the second illumination light are respectively guided to irradiate the surface of the sample to be measured. The first illumination light is reflected by the sample to be measured to form a bright-field signal light, and the second illumination light is scattered by the sample to be measured to form a dark-field signal light; The bright-field signal light and the dark-field signal light are transmitted along a common optical path and are spatially separated from each other; An objective lens that receives the bright-field signal light and the dark-field signal light and performs microscopic imaging respectively; the illumination modulation component is adapted to the exit pupil diameter of the objective lens and can suppress the reflection phenomenon that occurs around the exit pupil plane of the objective lens for the first illumination light; there is also an illumination lens group between the illumination modulation component and the objective lens. The first illumination light emitted by the illumination modulation component is sequentially irradiated onto the surface of the sample to be measured after passing through the illumination lens group and the objective lens; the exit aperture of the spatial filtering group, the exit pupil diameter of the objective lens, the focal length of the illumination lens group, and the focal length of the front relay lens group or the rear relay lens group satisfy the following relationship: D 瞳 / D 滤波 =F 照明 / F 中继 ; Among them, D 瞳 represents the exit pupil diameter of the objective lens, D 滤波 represents the light output aperture of the spatial filter group, F 照明 represents the focal length of the illumination lens group, F 中继 represents the focal length of the front relay lens group or the rear relay lens group; An imaging component that receives the bright-field signal light and the dark-field signal light exiting from the objective lens and performs bright-field imaging and dark-field imaging.

2. The bright and dark field detection device according to claim 1, wherein The spatial filtering group is located at the Fourier plane between the front relay lens group and the rear relay lens group.

3. The bright and dark field detection device according to claim 2, wherein The spatial filtering group includes a spatial filter and an electric turntable provided on the spatial filter. A plurality of light exit holes with different exit apertures are provided on the electric turntable, and the light exit holes can be switched so that the exit aperture matches the exit pupil diameter of the objective lens.

4. The bright-dark field detection device according to claim 2, characterized in that The spatial filtering group includes a spatial filter and an electric aperture stop provided on the spatial filter. The electric aperture stop can be adjusted so that the exit aperture matches the exit pupil diameter of the objective lens.

5. The bright and dark field detection device according to claim 2, characterized in that The illumination modulation component further includes a plurality of filter plates with different colors, and the colors of the filter plates are different from the background color of the sample to be measured.

6. The bright and dark field detection device according to claim 1, wherein, The objective lens includes a plurality of sub-objective lenses with different exit pupil diameters; the first illumination light enters the surface of the sample to be measured through the sub-objective lens, and the bright-field signal light and the dark-field signal light enter the imaging component respectively from both sides of the optical axis of the sub-objective lens; the bright-field signal light and the dark-field signal light are transmitted along a common optical path between the sub-objective lens participating in the optical path transmission and the imaging component and are spatially separated from each other; the sub-objective lens participating in the optical path transmission can be switched, and the illumination modulation component is adapted to the exit pupil diameter of the sub-objective lens participating in the optical path transmission.

7. The bright and dark field detection device according to claim 1, wherein There is also a beam splitting element between the illumination modulation component and the objective lens; the first illumination light enters the objective lens after passing through the beam splitting element; both the bright-field signal light and the dark-field signal light sequentially pass through the objective lens and the beam splitting element and enter the imaging component; the bright-field signal light and the dark-field signal light are transmitted along a common optical path between the objective lens and the beam splitting element and between the beam splitting element and the imaging component.

8. The bright and dark field detection device according to claim 7, characterized in that An imaging lens group is further provided between the spectroscopic element and the imaging assembly; the bright-field signal light and the dark-field signal light emitted from the spectroscopic element enter the imaging assembly through the imaging lens group, and the bright-field signal light and the dark-field signal are transmitted in a common optical path between the spectroscopic element and the imaging lens group.

9. The bright and dark field detection device according to claim 7, wherein A focus detection assembly is further provided between the spectroscopic element and the objective lens; the focus detection assembly includes: A dichroic mirror disposed between the spectroscopic element and the objective lens; An autofocus module for emitting a detection light; the detection light is irradiated onto the surface of the sample to be measured after passing through the dichroic mirror and the objective lens, and a focus detection light is formed by reflection on the surface of the sample to be measured, and the focus detection light reaches the autofocus module along the original optical path, and the autofocus module is further used to determine the position of the front focal plane of the sample to be measured relative to the objective lens by using the focus detection light.

10. The bright and dark field detection device according to claim 1, characterized in that, The imaging assembly includes an optical separation element, a bright-field camera and a dark-field camera; wherein, the optical separation element collects the bright-field signal light and the dark-field signal light and performs optical path separation, so that the dark-field signal light and the bright-field signal light respectively enter the dark-field camera and the bright-field camera to perform dark-field imaging and bright-field imaging.

11. The bright and dark field detection device according to claim 10, wherein The optical separation element includes a first reflecting surface and a second reflecting surface; The first reflecting surface is used for receiving the bright-field signal light and reflecting the bright-field signal light into the bright-field camera; The second reflecting surface is used for receiving the dark-field signal light and reflecting the dark-field signal light into the dark-field camera.

12. A light and dark field detection method, applied to the light and dark field detection device according to any one of claims 1 to 11, characterized in that, The bright-field and dark-field detection method includes: Controlling a bright-field light source to emit a first illumination light to an illumination modulation assembly, the illumination modulation assembly including a spatial filter group, a front relay lens group and a rear relay lens group; According to the exit pupil diameter of the objective lens, controlling the illumination modulation assembly to modulate the first illumination light, including: adjusting the light exit aperture of the spatial filter group according to the exit pupil diameter of the objective lens, so that the light exit aperture of the spatial filter group, the exit pupil diameter of the objective lens, the focal length of an illumination lens group disposed between the illumination modulation assembly and the objective lens, and the focal length of the front relay lens group or the rear relay lens group satisfy the following corresponding relationship: D 瞳 / D 滤波 =F 照明 / F 中继 ; Among them, D 瞳 represents the exit pupil diameter of the objective lens, D 滤波 represents the light output aperture of the spatial filter group, F 照明 represents the focal length of the illumination lens group, F 中继 represents the focal length of the front relay lens group or the rear relay lens group; The modulated first illumination light is irradiated onto the sample to be measured through the objective lens, and controlling a dark-field light source to emit a second illumination light to the sample to be measured; The first illumination light is reflected by the sample to be measured to form a bright-field signal light, and the second illumination light is scattered by the sample to be measured to form a dark-field signal light; The bright-field signal light and the dark-field signal light are transmitted along a common optical path through the objective lens and are spatially separated from each other, and the bright-field signal light and the dark-field signal light are transmitted to the imaging assembly to perform bright-field imaging and dark-field imaging respectively.

13. The bright and dark field detection method according to claim 12, characterized in that The spatial filter group is located at the Fourier plane between the front relay lens group and the rear relay lens group.

14. The bright and dark field detection method according to claim 13, wherein The spatial filter group includes a spatial filter and an electric turntable disposed on the spatial filter, and a plurality of light exit holes with different light exit apertures are provided on the electric turntable; In the process of adjusting the light output aperture of the spatial filtering group according to the exit pupil diameter of the objective lens, control the rotation of the electric turntable so that the light output aperture of the light output hole and the exit pupil diameter of the objective lens satisfy the corresponding relationship.

15. The bright and dark field detection method according to claim 13, wherein The spatial filtering group includes a spatial filter and an electric diaphragm provided on the spatial filter; In the process of adjusting the light output aperture of the spatial filtering group according to the exit pupil diameter of the objective lens, control the size of the light output aperture of the electric diaphragm so that the light output aperture of the electric diaphragm and the exit pupil diameter of the objective lens satisfy the corresponding relationship.

Images