Light and dark field detection device and method

Abstract

The invention relates to the technical field of optical detection, in particular to a bright and dark field detection device and method.First illumination light emitted by a bright field light source is modulated through an illumination modulation assembly, then the first illumination light and second illumination light emitted by a dark field light source are guided to irradiate the surface of a to-be-detected sample, and the first illumination light is reflected by the to-be-detected sample to form bright field signal light; the second illumination light is scattered by the sample to be detected to form dark field signal light, and the bright field signal light and the dark field signal light are transmitted along a common light path and are mutually separated in space; an objective lens matched with the illumination modulation assembly receives and microscopically amplifies the bright field signal light and the dark field signal light; the imaging assembly receives the bright-field signal light and the dark-field signal light and carries out bright-field imaging and dark-field imaging. Through a bright and dark field common-path sub-view-field design, simultaneous imaging detection of bright and dark fields is realized; in addition, by arranging the illumination modulation assembly, the reflection phenomenon of illumination light on the periphery of the exit pupil plane of the objective lens is inhibited, and interference of stray light on imaging is eliminated.

Description

Technical Field

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

[0002] The inevitable contamination and defects caused by manufacturing errors during the semiconductor chip processing are the main reasons for chip failure. 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 contactless, and is the most commonly used method for wafer detection.

[0003] Detection speed and detection accuracy are important parameters for wafer defect detection, where detection accuracy refers to the minimum size of a defect that can be detected. Increasing the magnification can obtain a smaller optical resolution and improve detection accuracy, but it also reduces the detection speed. 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-sized particles. As long as the scattering signal of small-sized 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 solution of simultaneous scanning of bright field and dark field can not only improve the detection accuracy, but also improve the detection speed.

[0004] In bright-field and dark-field detection devices, considering that there are many types of defects that may exist on the chip, bright-field imaging and dark-field imaging have different resolution capabilities for different types of defects. Therefore, the simultaneous use of bright-field imaging and dark-field imaging detection methods will improve the detection capability of these defects. At this time, when scanning the sample to be tested in the bright field and dark field at the same time, in addition to preventing crosstalk through reasonable field of view bias design, it is often accompanied by the influence of stray light, which leads to a technical problem of reduced optical imaging signal-to-noise ratio. Summary of the invention

[0005] In view of this, in order to reduce the interference of stray light on imaging in a bright and dark field detection device, the present invention provides a bright and dark field detection device and method, which adopts a common optical path design for bright field and dark field, realizes simultaneous imaging of bright and dark fields by setting different illumination areas for bright field and dark field, and then performs imaging through an imaging component, so that the bright field and dark field are scanned simultaneously; at the same time, an illumination modulation component is set to change the size of the illumination light beam to match the exit pupil diameter of the objective lens, significantly suppresses the reflection phenomenon of the illumination light on the periphery of the exit pupil surface of the objective lens, and avoids the interference of stray light on imaging by eliminating the stray light formed by the reflection phenomenon, thereby achieving a good dark field imaging effect and improving the defect detection capability under the dark field; in addition, the illumination modulation component can also adjust the angular spectrum frequency of the bright field illumination, realize illumination of multiple angular spectrum frequencies, reduce the brightness of the background pattern of the sample to be tested, minimize stray light, highlight defects, and improve the contrast of defects.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: A bright and dark field detection device comprises: a bright field light source, emitting a first illumination light; an illumination modulation component, modulating the first illumination light; a dark field light source, emitting a second illumination light; the first illumination light and the second illumination light are respectively guided to illuminate the surface of a sample to be tested, the first illumination light is reflected by the sample to be tested to form a bright field signal light, and the second illumination light is scattered by the sample to be tested 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, receiving the bright field signal light and the dark field signal light and performing microscopic imaging respectively, 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 at the periphery of the exit pupil surface of the objective lens; an imaging component, receiving the bright field signal light and the dark field signal light emitted by the objective lens, and performing bright field imaging and dark field imaging.

[0007] In some embodiments, the illumination modulation assembly includes a front relay mirror group, a spatial filter group, and a rear relay mirror group; wherein the spatial filter group is located at the Fourier plane between the front relay mirror group and the rear relay mirror group; the light exit aperture of the spatial filter group matches the exit pupil diameter of the objective lens, and the spatial filter group is conjugate with the exit pupil plane of the objective lens.

[0008] In some embodiments, the spatial filter group includes a spatial filter and an electric turntable arranged on the spatial filter, on which a plurality of light exit holes with different light exit apertures are provided, and the light exit holes can be switched so that the light exit aperture matches the exit pupil diameter of the objective lens.

[0009] In some embodiments, the spatial filter group includes a spatial filter and a motorized aperture arranged on the spatial filter, and the motorized aperture can be adjusted to match the exit pupil diameter of the objective lens.

[0010] In some embodiments, the illumination modulation component further includes a plurality of filters of different colors, and the color of the filters is different from the background color of the sample to be measured.

[0011] In some embodiments, the objective lens 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 through the sub-objective lens, and the bright field signal light and the dark field signal light are respectively incident on the imaging component through 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 the same optical path between the sub-objective lens and the imaging component participating in the optical path transmission, and are spatially separated from each other; the sub-objective lens participating in the optical path transmission is switchable, and the illumination modulation component is adapted to the exit pupil diameter of the sub-objective lens participating in the optical path transmission.

[0012] In some embodiments, a spectroscopic 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 spectroscopic element; the bright field signal light and the dark field signal light are sequentially passed through the objective lens and the spectroscopic element and are incident on 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 spectroscopic element, and between the spectroscopic element and the imaging component.

[0013] In some embodiments, an illumination lens group is further provided between the illumination modulation assembly and the objective lens, and the first illumination light emitted by the illumination modulation assembly is sequentially irradiated to the surface of the sample to be measured after passing through the illumination lens group and the objective lens; the light 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: D 瞳 / D 滤波 =F 照明 / F 中继 ; Among them, D 瞳 Indicates the exit pupil diameter of the objective lens, D 滤波 Represents the light output aperture of the spatial filter group, F 照明 Indicates the focal length of the lighting lens assembly, F 中继 Indicates the focal length of the front relay lens group or the rear relay lens group.

[0014] In some embodiments, an imaging lens group is further provided between the spectroscopic element and the imaging component; the bright field signal light and the dark field signal light emitted from the spectroscopic element are incident into the imaging component through the imaging lens group, and the bright field signal light and the dark field signal are transmitted along a common optical path between the spectroscopic element and the imaging lens group.

[0015] In some embodiments, a focusing detection assembly is further provided between the beam splitter and the objective lens; the focusing detection assembly includes: a dichroic mirror, disposed between the beam splitter and the objective lens; an automatic focusing detection module, for emitting detection light; the detection light is irradiated to the surface of the sample to be tested after passing through the dichroic mirror and the objective lens, and is reflected on the surface of the sample to be tested to form a focusing detection light, and the focusing detection light reaches the automatic focusing detection module along the original optical path, and the automatic focusing detection module is also used to use the focusing detection light to determine the position of the sample to be tested relative to the front focal plane of the objective lens.

[0016] 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 bright field signal light and dark field signal light and performs optical path separation, so that the dark field signal light and the bright field signal light enter the dark field camera and the bright field camera respectively, so as to perform dark field imaging and bright field imaging.

[0017] In some embodiments, the optical separation element includes a first reflective surface and a second reflective surface; the first reflective surface is used to receive bright field signal light and reflect the bright field signal light into the bright field camera; the second reflective surface is used to receive dark field signal light and reflect the dark field signal light into the dark field camera.

[0018] A bright and dark field detection method, comprising: Controlling the bright field light source to emit a first illumination light to the illumination modulation component; According to the exit pupil diameter of the objective lens, controlling the illumination modulation component to modulate the first illumination light; The modulated first illumination light irradiates the sample to be tested through the objective lens, and the dark field light source is controlled to emit the second illumination light to the sample to be tested; The first illumination light is reflected by the sample to be tested to form a bright field signal light, and the second illumination light is scattered by the sample to be tested 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. The bright field signal light and the dark field signal light are transmitted to the imaging component to perform bright field imaging and dark field imaging respectively.

[0019] In some embodiments, an illumination lens group is further provided between the illumination modulation assembly and the objective lens; the illumination modulation assembly includes a front relay lens group and a rear relay lens group, and a spatial filter group located at a Fourier plane between the front relay lens group and the rear relay lens group; 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: The light exit aperture of the spatial filter group is adjusted 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 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: D 瞳 / D 滤波 =F 照明 / F 中继 ; Among them, D pupil represents the exit pupil diameter of the objective lens, D filter represents the light output aperture of the spatial filter group, F illumination represents the focal length of the illumination mirror group, and F relay represents the focal length of the front relay mirror group or the rear relay mirror group.

[0020] In some embodiments, the spatial filter group includes a spatial filter and an electric turntable disposed on the spatial filter, wherein a plurality of light exit holes with different light exit apertures are disposed on the electric turntable; In the process of adjusting the light exit aperture of the spatial filter group according to the exit pupil diameter of the objective lens, the electric turntable is controlled to rotate so that the light exit aperture of the light exit hole satisfies the corresponding relationship with the exit pupil diameter of the objective lens.

[0021] In some embodiments, the spatial filter group includes a spatial filter, and a motorized aperture disposed on the spatial filter; In the process of adjusting the light exit aperture of the spatial filter group according to the exit pupil diameter of the objective lens, the light exit aperture of the electric diaphragm is controlled so that the light exit aperture of the electric diaphragm satisfies a corresponding relationship with the exit pupil diameter of the objective lens.

[0022] Compared with the prior art, the invention can achieve the following beneficial effects: (1) In the bright and dark field detection device and method created by the present invention, a common optical path design is adopted for the bright field and the dark field, and the illumination areas of the bright field and the dark field are different to realize simultaneous imaging of the bright field and the dark field, and then imaging is performed through the imaging component, so that the bright field and the dark field are scanned simultaneously; the illumination 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 at the periphery of the exit pupil surface of the objective lens, and avoiding the interference of the stray light on the imaging by eliminating the stray light formed by the reflection phenomenon, thereby achieving a good dark field imaging effect and improving the defect detection capability under the dark field; in addition, the illumination modulation component is set to adjust the angular spectrum frequency of the bright field illumination, realize illumination of multiple angular spectrum frequencies, reduce the brightness of the background pattern of the sample to be tested, minimize stray light, highlight defects, and improve the contrast of defects; (2) In the bright and dark field detection device and method created by the present invention, the illumination modulation component includes one or more of an illumination light path relay lens group, a spatial filter and a filter; the spatial filter is conjugate with the exit pupil surface of the objective lens, and an electric turntable or electric diaphragm that can change the light exit hole is provided on the spatial filter, so that the size of the illumination light beam passing through the light exit hole matches the exit pupil diameter of the objective lens, thereby eliminating stray light formed by the peripheral reflection phenomenon of the exit pupil surface of the objective lens, avoiding the interference of stray light on imaging, thereby achieving a good dark field imaging effect and improving the defect detection capability under dark field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 A schematic diagram of the structure of the bright and dark field detection device according to an embodiment of the present invention; Figure 2 A schematic diagram of the stray light generation principle described in an embodiment of the present invention; Figure 3 A schematic diagram of an electric turntable and an electric diaphragm according to an embodiment of the present invention; Figure 4 A schematic flow chart of the bright and dark field detection method described in an embodiment of the present invention.

[0024] Description of reference numerals: 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 filter group; 7. Rear relay lens group; 8. Field diaphragm; 9. Illumination lens group; 10. Light exit hole; 11. Beam splitter; 12. Reflector; 13. Imaging lens group; 14. Dichroic mirror; 15. Autofocus module; 16. Bright field camera; 17. Dark field camera; 18. First reflection surface; 19. Second reflection surface; 31. Exit pupil surface; 32. Exit pupil surface periphery. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0026] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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 therefore cannot be understood as a limitation on 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 technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0028] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0029] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0030] like Figure 1 As shown, the bright and dark field detection device described in the embodiment of the 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, the modulated first illumination light is reflected by the sample to be tested 4 to form a bright field signal light, and the second illumination light is scattered by the sample to be tested 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 during the propagation process and are spatially separated from each other. 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.

[0031] It should be noted that the illumination modulation component has an adjustable light port, and the light port can be adapted to the exit pupil diameter of the objective lens 3. This is because the 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. If there is no illumination modulation component, when the objective lens 3 changes (that is, the exit pupil diameter of the objective lens 3 changes), the beam size of the first illumination light will be larger than the exit pupil diameter of the objective lens 3, causing part of the light to irradiate the exit pupil plane of the objective lens 3, and the other part of the light to irradiate the periphery of the exit pupil plane of the objective lens, resulting in reflection of the light irradiated on the periphery of the exit pupil plane of the objective lens 3, thereby forming stray light, as shown in the following figure. Figure 2 shown.

[0032] Since the bright field and dark field are detected at the same time and the bright field and dark field share the same optical path, stray light will enter the imaging area of ​​the bright field and dark field, making the detection noise larger, the signal-to-noise ratio lower, and the detection accuracy lowered; since dark field imaging is particularly sensitive to the input amount of light, a small amount of stray light may cause distortion of dark field imaging, so 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.

[0033] It should be noted that the objective lens 3 has an entrance pupil surface and an exit pupil surface. Usually, the side facing the sample 4 to be measured is the entrance pupil surface, and the side facing away from the sample 4 to be measured is the exit pupil surface. Figure 2 Reference numeral 31 is the exit pupil surface of the objective lens 3 , which allows the first illumination light to enter the exit pupil surface 31 and be emitted from the entrance pupil surface 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 surface 31 of the objective lens 3 . Figure 2The periphery 32 of the exit pupil surface of the objective lens 3 can be understood as a structural component of a fixed lens, which can reflect the light irradiated on the surface of the structural component, and the reflected light is mixed into the transmission optical path 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 transmits the bright field signal light and the dark field signal light in a common optical path and divided field of view, the first illumination light is not incident on the entire exit pupil surface of the objective lens 3, but is incident on a part of the exit pupil surface of the objective lens 3 and is located in an area on one side of the optical axis, and the side area also allows the bright field illumination light to be emitted; the other part of the exit pupil surface of the objective lens 3 is located in an area on the other side of the optical axis, and the side area allows the dark field illumination light to be emitted.

[0034] In one embodiment, it is preferred that the bright field light source 1 and the dark field light source 2 emit continuous first illumination light and second illumination light respectively. For example, a high brightness LED light source is used to emit continuous illumination light.

[0035] In some embodiments, the illumination modulation assembly includes a front relay lens group 5, a spatial filter group 6, and a rear relay lens group 7. The spatial filter group 6 is located at the Fourier plane between the front relay lens group 5 and the rear relay lens group 7 (i.e., the central focal plane of the front relay lens group 5 and the rear relay lens group 7), the light exit aperture of the spatial filter group 6 matches the exit pupil diameter of the objective lens 3, and the spatial filter group 6 is conjugate with the exit pupil plane of the objective lens 3.

[0036] In one embodiment, a field stop 8 is provided on the light exit 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, the field of view is modulated by the field stop 8. The front relay lens group 5 and the rear relay lens group 7 are symmetrically placed using the same lenses, and the focal lengths of the two relay lens groups range from 50 to 150 mm. The front relay lens group 5, the spatial filter group 6, the rear relay lens group 7, the field stop 8, and the light exit surface of the bright field light source 1 form a 4F system.

[0037] In some embodiments, an illumination lens group 9 is further provided between the illumination modulation assembly and the objective lens 3, and the first illumination light emitted by the illumination modulation assembly is sequentially irradiated to the surface of the sample 4 through the illumination lens group 9 and the objective lens 3. The light exit 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 length of the front relay lens group 5 or the rear relay lens group 7 satisfy the following relationship: D 瞳 / D 滤波 =F 照明 / F 中继 .

[0038] Among them, D 瞳 Denotes the exit pupil diameter of objective lens 3, D 滤波 represents the light output aperture of spatial filter group 6, F 照明 Indicates the focal length of the lighting lens group 9, F 中继Indicates the focal length of the front relay lens group 5 or the rear relay lens group 7. Exit pupil diameter D 瞳 It is related to the focal length f and numerical aperture NA of the objective lens 3, namely: D 瞳 =2×f×NA.

[0039] In actual use, the focal length 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 based on the above relationship.

[0040] In a certain embodiment, after comprehensively considering the space limitation of the entire bright and dark field detection device, the field limitation of the illumination system, and the aperture limitation of the illumination system, the focal length of the illumination lens group 9 is preferably in the range of 150-250 mm. For example, when the focal length of the illumination lens group 9 is selected to be 200 mm, and the focal lengths of the front relay lens group 5 and the rear relay lens group 7 are selected to be 100 mm, then: D 瞳 / D 滤波 =F 照明 / F 中继 =200 / 100=2.

[0041] That is, determine the exit pupil diameter D of the objective lens 3 瞳 is the light output aperture D of spatial filter group 6 滤波 twice as much.

[0042] In some embodiments, the objective lens 3 includes a plurality of sub-objective lenses with different exit pupil diameters, the first illumination light is incident on the surface of the sample 4 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 through 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 the same optical path between the sub-objective lens and the imaging component 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 component is adapted to the exit pupil diameter of the sub-objective lens participating in the optical path transmission.

[0043] In one embodiment, the objective lens 3 includes five sub-objective lenses with 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 relationship, 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 light output aperture D of the spatial filter group 6 滤波 As shown in Table 1: Table 1. Correlation between objective lens and spatial filter group

[0044] 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 light exit aperture of the spatial filter group 6 being 2, it can be calculated that the light exit apertures of the spatial filter group 6 are 8 mm, 12 mm, 10 mm, 9 mm and 5.5 mm respectively. In actual use, the focal lengths of the front relay lens group 5, the rear relay lens group 7 and the illumination lens group 9 are adjusted as needed, and the objective lenses 3 with different exit pupil diameters are selected. It is only necessary to change the light exit aperture of the spatial filter group 6 after calculating according to the above formula.

[0045] If there is no spatial filter group 6, in order to ensure the illumination of each magnification, the diameter of the light spot illuminated on the exit pupil surface of the objective lens 3 should be at least 24mm (taking 2.5× as the maximum case), and the light exit aperture of the spatial filter group 6 is 12mm; at this time, when the magnification of the objective lens 3 is switched to 20× (that is, the exit pupil diameter is 11mm), the diameter of the illumination light spot is larger than the exit pupil diameter of the objective lens (24mm>11mm), generating stray light. When the spatial filter group 6 is used, combined with Table 1, by adjusting the light exit aperture of the spatial filter group 6 to 5.5mm, the light spot illuminated on the exit pupil surface of the objective lens 3 becomes 11mm, which just matches the exit pupil diameter of 20×, reducing stray light.

[0046] In some embodiments, the spatial filter group 6 includes a spatial filter, and an electric turntable or electric diaphragm arranged on the spatial filter. Since the aperture size of the spatial filter is related to the angular spectrum frequency of light propagation, and it is necessary to achieve matching between the spatial filter and the exit pupil diameter of the objective lens 3, the aperture size of the spatial filter is changed by arranging an electric turntable or electric diaphragm with an adjustable light exit aperture on the spatial filter, and the exit pupil diameter of the objective lens 3 is matched by changing the light beam size, so as to avoid the light beam generating stray light due to reflection at the periphery of the exit pupil surface of the objective lens.

[0047] In one embodiment, the motorized turntable and the motorized iris are as follows: Figure 3 A plurality of light exit holes 10 with different light exit apertures are provided on the electric turntable, and the light exit holes 10 can be switched so that the light exit apertures match the exit pupil diameter of the objective lens 3. Specifically, the electric turntable can be provided with 5 light exit holes 10 with different light exit apertures, and the 5 light exit holes 10 are evenly arranged on the electric turntable in the circumferential direction, as shown in FIG. Figure 3 As shown in (a) in FIG. 1 , when the objective lens 3 is switched, the motor drives the electric turntable to rotate to complete the switching of the light exit hole 10, thereby completing the adjustment of the light exit aperture of the spatial filter. Figure 3 As shown in (b) in FIG. 1 , the size of the aperture is changed by electrically controlling the diameter of the light exit hole 10 on the electric diaphragm, so that the light exit aperture of the spatial filter matches the exit pupil diameter of the objective lens 3 .

[0048] In some embodiments, the illumination modulation assembly further includes a plurality of filters of different colors, and the color of the filters is different from the background color of the sample 4 to be tested. In one embodiment, when the background color is red, the color of the filters is preferably blue, green or yellow.

[0049] In some embodiments, a beam splitter 10 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 splitter 11, and the bright field signal light and the dark field signal light are incident on the imaging component through the objective lens 3 and the beam splitter 11 in sequence. 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 splitter 11, and between the beam splitter 11 and the imaging component.

[0050] In one embodiment, the beam splitter 11 is a beam splitter prism and is disposed between the illumination lens group 9 and the objective lens 3. In this case, 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, and the illumination lens group 9 injects the modulated first illumination light into the beam splitter 11, and the beam splitter 10 injects the first illumination light into the objective lens 3. In order to fold the optical path and reduce the volume of the device provided by the present invention, a reflector 12 for reflecting the first illumination light is provided between the beam splitter 11 and the illumination lens group 9.

[0051] In some embodiments, an imaging lens group 13 is further provided between the beam splitter element 11 and the imaging component. The bright field signal light and the dark field signal light emitted from the beam splitter element 11 are incident into the imaging component through the imaging lens group 13, and the bright field signal light and the dark field signal light are transmitted in a common optical path between the beam splitter element 11 and the imaging lens group 13.

[0052] In some embodiments, a focus detection assembly is further provided between the beam splitter 11 and the objective lens 3. The focus detection assembly includes a dichroic mirror 14 and an automatic focus detection module 15. The dichroic mirror 14 is provided between the beam splitter 11 and the objective lens 3, and the automatic focus detection module 15 is used to emit a detection light, which is irradiated to the surface of the sample 4 to be tested after passing through the dichroic mirror 14 and the objective lens 3, and is reflected on the surface of the sample 4 to be tested to form a focus detection light, and the focus detection light arrives at the automatic focus detection module 15 along the original optical path, and the automatic focus detection module 15 is also used to determine the position of the sample 4 to be tested relative to the front focal plane of the objective lens 3 using the focus detection light.

[0053] In some embodiments, the imaging assembly includes an optical separation element, a bright field camera 16, and a dark field camera 17. 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 enter the dark field camera 17 and the bright field camera 16 respectively, so as to perform dark field imaging and bright field imaging.

[0054] In some embodiments, the optical separation element includes a first reflective surface 18 and a second reflective surface 19. The first reflective surface 18 is used to receive the bright field signal light and reflect the bright field signal light into the bright field camera 16; the second reflective surface 19 is used to receive the dark field signal light and reflect the dark field signal light into the dark field camera 17.

[0055] Based on the light and dark field detection device provided by the present invention, a light and dark field detection method is also provided. Figure 1~Figure 4 , methods include: S1: Control the bright field light source to emit a first illumination light to the illumination modulation component.

[0056] S2: According to the exit pupil diameter of the objective lens, control the illumination modulation component to modulate the first illumination light.

[0057] In some embodiments, the light exit aperture of the spatial filter group 6 in the illumination modulation assembly is adjusted according to the exit pupil diameter of the objective lens 3, so that the light exit 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: D 瞳 / D 滤波 =F 照明 / F 中继 .

[0058] In one embodiment, the spatial filter group 6 includes a spatial filter and an electric turntable disposed on the spatial filter, and a plurality of light exit holes 10 with different light exit apertures are disposed on the electric turntable. At this time, the process of adjusting the light exit aperture of the spatial filter group according to the exit pupil diameter of the objective lens 3 includes: controlling the electric turntable to rotate so that the light exit aperture of the light exit hole 10 satisfies the corresponding relationship with the exit pupil diameter of the objective lens 3.

[0059] In one embodiment, the spatial filter group 6 includes a spatial filter and an electric diaphragm arranged on the spatial filter. At this time, the process of adjusting the light exit aperture of the spatial filter group according to the exit pupil diameter of the objective lens includes: controlling the aperture size of the light exit hole 10 of the electric diaphragm so that the aperture of the light exit hole 10 of the electric diaphragm satisfies the corresponding relationship with the exit pupil diameter of the objective lens 3.

[0060] S3: The modulated first illumination light irradiates the sample 4 to be tested via the objective lens 3 , and the dark field light source is controlled to emit the second illumination light to the sample 4 to be tested.

[0061] S4: The first illumination light is reflected by the sample to be tested 4 to form a bright field signal light, and the second illumination light is scattered by the sample to be tested 4 to form a dark field signal light.

[0062] 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 component to perform bright field imaging and dark field imaging respectively.

[0063] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0064] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A bright and dark field detection device, characterized in that: include: A bright field light source, emitting a first illumination light; an illumination modulation component, modulating the first illumination light; A dark field light source, emitting a second illumination light; The first illumination light and the second illumination light are respectively guided to illuminate the surface of the sample to be tested, the first illumination light is reflected by the sample to be tested to form a bright field signal light, and the second illumination light is scattered by the sample to be tested 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, receiving the bright field signal light and the dark field signal light and performing microscopic imaging respectively; 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 at the periphery of the exit pupil surface of the objective lens; An imaging component receives the bright field signal light and the dark field signal light emitted by the objective lens, and performs bright field imaging and dark field imaging.

2. The bright and dark field detection device according to claim 1, characterized in that: The illumination modulation component comprises a front relay mirror group, a spatial filter group and a rear relay mirror group; wherein the spatial filter group is located at the Fourier plane between the front relay mirror group and the rear relay mirror group; the light exit aperture of the spatial filter group matches the exit pupil diameter of the objective lens, and the spatial filter group is conjugate with the exit pupil plane of the objective lens.

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

4. The bright and dark field detection device according to claim 2, characterized in that: The spatial filter group includes a spatial filter and an electric diaphragm arranged on the spatial filter, and the electric diaphragm can be adjusted to make the resulting light aperture match 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 filters of different colors, and the colors of the filters are different from the background color of the sample to be tested.

6. The bright and dark field detection device according to claim 1, characterized in that: 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 through 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 the same 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 is switchable, 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, characterized in that: A spectroscopic element is also provided between the illumination modulation component and the objective lens; the first illumination light enters the objective lens after passing through the spectroscopic element; the bright field signal light and the dark field signal light are sequentially passed through the objective lens and the spectroscopic element and are incident on 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 spectroscopic element, and between the spectroscopic element and the imaging component.

8. The bright and dark field detection device according to claim 2, characterized in that: An illumination lens group is also provided between the illumination modulation component and the objective lens, and the first illumination light emitted by the illumination modulation component is sequentially irradiated to the surface of the sample to be tested after passing through the illumination lens group and the objective lens; The light 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: D 瞳 / D 滤波 =F 照明 / F 中继 ; Among them, D 瞳 Denotes the exit pupil diameter of the objective lens, D 滤波 represents the light output aperture of the spatial filter group, F 照明 Indicates the focal length of the illumination lens assembly, F 中继 Indicates the focal length of the front relay lens group or the rear relay lens group.

9. The bright and dark field detection device according to claim 7, characterized in that: An imaging lens group is also provided between the spectroscopic element and the imaging component; the bright field signal light and the dark field signal light emitted from the spectroscopic element are incident on the imaging component through the imaging lens group, and the bright field signal light and the dark field signal are transmitted along a common optical path between the spectroscopic element and the imaging lens group.

10. The bright and dark field detection device according to claim 7, characterized in that: A focus detection assembly is also provided between the light splitting element and the objective lens; the focus detection assembly comprises: A dichroic mirror, disposed between the beam splitting element and the objective lens; The automatic focusing module is used to emit detection light; the detection light is irradiated to the surface of the sample to be tested after passing through the dichroic mirror and the objective lens, and is reflected on the surface of the sample to be tested to form a focus detection light, and the focus detection light reaches the automatic focusing module along the original optical path. The automatic focusing module is also used to use the focus detection light to determine the position of the sample to be tested relative to the front focal plane of the objective lens.

11. The bright and dark field detection device according to claim 1, characterized in that: 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 enter the dark field camera and the bright field camera respectively, so as to perform dark field imaging and bright field imaging.

12. The bright and dark field detection device according to claim 11, characterized in that: The optical separation element comprises a first reflective surface and a second reflective surface; The first reflective surface is used to receive the bright field signal light and reflect the bright field signal light into the bright field camera; The second reflective surface is used to receive the dark field signal light and reflect the dark field signal light into the dark field camera.

13. A bright and dark field detection method, applied to the bright and dark field detection device according to any one of claims 1 to 12, characterized in that: The bright and dark field detection method comprises: Controlling the bright field light source to emit a first illumination light to the illumination modulation component; According to the exit pupil diameter of the objective lens, controlling the illumination modulation component to modulate the first illumination light; The modulated first illumination light irradiates the sample to be tested through the objective lens, and controls the dark field light source to emit the second illumination light to the sample to be tested; The first illumination light is reflected by the sample to be tested to form a bright field signal light, and the second illumination light is scattered by the sample to be tested 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. 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.

14. The bright and dark field detection method according to claim 13, characterized in that: An illumination lens group is also provided between the illumination modulation assembly and the objective lens; the illumination modulation assembly comprises a front relay lens group and a rear relay lens group, and a spatial filter group located at a Fourier plane between the front relay lens group and the rear relay lens group; 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: The light exit aperture of the spatial filter group is adjusted 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 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: D 瞳 / D 滤波 =F 照明 / F 中继 ; Among them, D 瞳 Denotes the exit pupil diameter of the objective lens, D 滤波 represents the light output aperture of the spatial filter group, F 照明 Indicates the focal length of the illumination lens assembly, F 中继 Indicates the focal length of the front relay lens group or the rear relay lens group.

15. The bright and dark field detection method according to claim 14, characterized in that: The spatial filter group includes a spatial filter and an electric turntable arranged on the spatial filter, wherein the electric turntable is provided with a plurality of light exit holes with different light exit apertures; In the process of adjusting the light exit aperture of the spatial filter group according to the exit pupil diameter of the objective lens, the electric turntable is controlled to rotate so that the light exit aperture of the light exit hole and the exit pupil diameter of the objective lens satisfy the corresponding relationship.

16. The bright and dark field detection method according to claim 14, characterized in that: The spatial filter group includes a spatial filter and a motorized aperture arranged on the spatial filter; In the process of adjusting the light exit aperture of the spatial filter group according to the exit pupil diameter of the objective lens, the size of the light exit aperture of the electric aperture is controlled so that the light exit aperture of the electric aperture and the exit pupil diameter of the objective lens satisfy the corresponding relationship.

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