CN117723545A

CN117723545A - Lighting device, detection method, adjustment method and light source design method

Info

Publication number: CN117723545A
Application number: CN202311619934.9A
Authority: CN
Inventors: 黄鑫; 郑军
Original assignee: Matrixtime Robotics Shanghai Co ltd
Current assignee: Matrixtime Robotics Shanghai Co ltd
Priority date: 2023-11-29
Filing date: 2023-11-29
Publication date: 2024-03-19

Abstract

The embodiment of the application provides a lighting device, a detection device and a method for detecting, adjusting and designing a light source, and relates to the technical field of visual lighting, the device comprises one or more lighting branch structures, the lighting branch structures comprise a light source, a light homogenizing cavity, a lighting lens group and the like, the light homogenizing cavity consists of a cavity with one end being an incident light end face and the other end being an emergent light end face, the light source is arranged on one side of the incident light end face, and the lighting lens group is arranged on one side of the emergent light end face; the light source provides incident light, the incident light is obliquely irradiated to the surface of the sample through the light homogenizing cavity and the illumination lens group, and the azimuth angle of the illumination branch structure is configured, so that the emergent light end face is conjugated with the surface of the sample, namely the emergent light face of the light homogenizing cavity is effectively conjugated and projected on the surface of the sample after passing through the illumination lens group, so that the energy utilization rate of the light source is improved, the illumination uniformity is improved, and the illumination power density is improved.

Description

Lighting device, detection method, adjustment method and light source design method

Technical Field

The application relates to the technical field of visual illumination, in particular to an illumination device, a detection device and detection, adjustment and light source design methods.

Background

Dark field illumination techniques are widely used in the field of instrument vision, such as surface defect detection. Dark field illumination refers to the projection of an illumination beam onto the sample surface to be tested at a very large angle of incidence, and if there are defective features on the sample surface, some portion of the light diffusely reflected from the defective features may enter the objective lens for imaging, and these defective features are reflected as bright images in a dark field of view, which may ultimately be observed in the eyepiece. The illumination device of the annular dark field detection device provides uniform illumination light for detecting defect characteristics such as pits, protrusions and scratches on the surface of the sample, and therefore the uniformity of the illumination light of the illumination device determines the detection quality of the defects.

Currently, the existing dark field illumination device uses a conductive optical fiber as a light conduction medium to conduct the light emitted by a light source from an incident end to an emergent end and then emit the light, so as to perform dark field illumination on the surface of a sample. Because the energy difference of each optical fiber of the lighting device is large, the uniformity of the emergent light of the lighting device is reduced, and the defect detection quality is affected.

Disclosure of Invention

An object of the embodiment of the application is to provide a lighting device, a detection method, a regulation method and a light source design method, by arranging a lighting branch structure, the lighting branch structure comprises a light source, a light homogenizing cavity, a lighting lens group and other structures, wherein the light homogenizing cavity is composed of a cavity with one end being an incident light end face and the other end being an emergent light end face. The light source is arranged on one side of the incident light end face, the illumination lens group is arranged on one side of the emergent light end face, and the azimuth angle of the illumination branch structure is configured, so that the emergent light end face is conjugate with the sample surface, namely, the light emergent face of the light homogenizing cavity is effectively conjugate projected on the sample surface after passing through the illumination lens group, so that the energy utilization rate of the light source is improved, the illumination uniformity is improved, and the technical problem is solved.

An embodiment of the present application provides a lighting device, including: an illumination branching structure; the lighting branch structure comprises: a light source, a light homogenizing cavity and an illumination lens group; the dodging cavity comprises: an incident light end face, a cavity and an emergent light end face; the incident light end face and the emergent light end face are arranged at two ends of the cavity; the light source is arranged on one side of the incident light end face; the illumination lens group is arranged on one side of the emergent light end face, and the illumination lens group enables the emergent light end face to be conjugate with the surface of the sample; the light source in the illumination branch structure is used for providing incident light, the light homogenizing cavity is used for receiving the incident light and irradiating the incident light to the illumination lens group, and the illumination lens group is used for obliquely irradiating the sample based on the incident light; the azimuth angle of the illumination branch structure is configured to enable the emergent light end face to be conjugated and imaged to the surface of the sample through the lens of the illumination lens group.

In the above implementation manner, by setting the illumination branch structure, the illumination branch structure comprises a light source, a light homogenizing cavity, an illumination lens group and other structures, wherein the light homogenizing cavity is composed of a cavity with one end being an incident light end face and the other end being an emergent light end face, the light source is arranged on one side of the incident light end face, the illumination lens group is arranged on one side of the emergent light end face, and the azimuth angle of the illumination branch structure is configured, so that the emergent light end face is conjugated with the surface of a sample, namely, the light emergent face of the light homogenizing cavity is effectively conjugated and projected on the surface of the sample after passing through the illumination lens group, so that the energy utilization rate of the light source is improved, the illumination uniformity is improved, and the illumination power density is improved.

Optionally, the azimuth angle of the illumination branch structure includes: a first azimuth angle; the first azimuth angle is an included angle of an emergent light end face of the light homogenizing cavity relative to the surface of the sample; the first azimuth angle satisfies the relation: beta = δ×Μ; wherein, beta is the first azimuth angle, delta is the included angle between the light emitting direction of the light emitting end face of the light homogenizing cavity and the normal line of the sample surface, and M is the magnification of the projection lens of the illumination lens group.

In the implementation manner, through reasonable error range design of the first azimuth angle meeting the preset relational condition, a plurality of branch light paths can be more uniformly distributed to form annular illumination, and the uniformity of the annular illumination is improved; the light-emitting surface of the light-homogenizing cavity can be effectively projected on a sample in a conjugate mode, and the energy utilization rate is improved.

Optionally, the apparatus comprises: a plurality of illumination branch structures; the emergent light end face of the light homogenizing cavity is rectangular, the plurality of the illumination branch structures comprise a reference illumination branch structure, the incident light of the reference illumination branch structure has a reference incident surface relative to the sample, the image of the light spot extending direction on the light emergent end face of the light homogenizing cavity of the reference lighting branch structure has a reference extending direction, and the light emergent end face of the light homogenizing cavity is along the reference extending direction; the azimuth angle of the illumination branch structure further comprises: a second azimuth angle; the second azimuth angle is an included angle between the extending direction of the emergent light end face of the light homogenizing cavity and the reference extending direction; the second azimuth angle satisfies the relation: γ=θ/M; wherein, gamma is the second azimuth angle, M is the magnification of the projection lens of the illumination lens group, and θ is the included angle between the incident light of the illumination branch structure relative to the incident surface of the sample and the reference incident surface.

In the implementation manner, through reasonable error range design of the second azimuth angle meeting the preset relational condition, a plurality of branch light paths can be more uniformly distributed to form annular illumination, and the uniformity of the annular illumination is improved; the light beam splitter can ensure that emergent light spots of each branch illumination light path are perfectly overlapped in the center of the sample, improves the illumination uniformity and avoids the mechanism device with complex design to assist the eccentric adjustment.

Optionally, the reference incident plane coincides with or is perpendicular to the direction in which the light spot extends.

In the above implementation manner, the reference incident plane is coincident with or perpendicular to the extending direction of the light spot, so that the multiple imaging light spots generated by the multiple illumination branch structures can generate the effect of vertical overlapping or lateral overlapping.

Optionally, the illumination branch structures are uniformly distributed around the sample with the sample as a center.

In the implementation manner, the arrangement can meet the detection requirement of the surface defects of the sample and reduce the cost.

Optionally, the azimuth angle of the lighting branch structure further comprises: a third azimuth angle; the third azimuth angle is an included angle of projection of the optical axis of each adjacent two of the plurality of illumination branch structures on the surface of the sample; the third azimuth angle satisfies the relation: α=2pi/n; wherein n is the number of the plurality of illumination branch structures.

In the implementation manner, through reasonable error range design of the third azimuth angle meeting the preset relational expression condition, the relative spatial distribution positions of the plurality of illumination branch structures can be controlled, and the spatial uniformity of annular illumination is improved; the plurality of branch light paths can be more uniformly distributed to form annular illumination, and the uniformity of the annular illumination is improved.

Optionally, the lighting branch structure further comprises: and the turning mirror is positioned between the light homogenizing cavity and the sample and is used for changing the direction of light rays emitted from the emergent light end face of the light homogenizing cavity.

In the implementation manner, the refraction degree and direction of the light rays are controlled by adjusting the position and the angle of the turning mirror, so that good light spot uniformity can be realized.

Optionally, the turning mirror is arranged between the outgoing light end face of the light homogenizing cavity and the illumination lens group; or between the illumination lens group and the sample.

In the implementation manner, by arranging the turning mirror, more compact light path design and good light spot uniformity can be realized.

Optionally, the illumination lens group includes: a first lens and a second lens; the first lens is arranged on one side close to the emergent light end face of the light homogenizing cavity, and the second lens is arranged on one side close to the sample; the deflection mirror is arranged between the first lens and the second lens and is used for deflecting the emergent light rays passing through the first lens from the light homogenizing cavity from the vertical direction vertical to the sample surface to the oblique direction relative to the sample surface, so that the emergent light rays pass through the second lens and then obliquely irradiate the sample surface.

In the implementation mode, the light path is folded by arranging the folding mirror in the lens light path of the illumination lens group, so that the size of the transverse light path is reduced, the space volume of the illumination branch structure is saved, and the manufacturing cost is reduced.

Optionally, the lighting branch structure further comprises: and the dodging cavity adjusting mechanism is used for adjusting the light spot size and direction of the light at the incident light end surface of the dodging cavity and/or the light spot size and direction of the light at the emergent light end surface of the dodging cavity.

In the implementation manner, through the design of the uniform light cavity adjusting mechanism, the adjustment of the size and the direction of the light spot can be realized under the condition that the whole uniform light cavity structure is not changed, and the illumination requirement of a complex sample is improved.

Optionally, the dodging cavity adjusting mechanism is arranged outside the incident light end face and/or outside the emergent light end face of the dodging cavity.

In the implementation manner, the adjusting mechanism of the dodging cavity is arranged on any one side or multiple sides of the dodging cavity, so that flexible adjustment of the azimuth angle of the dodging cavity is realized, and the illumination requirement of a complex sample is improved.

Optionally, the dodging cavity is a reflecting cavity structure formed by splicing and enclosing reflecting mirrors, and the dodging cavity adjusting mechanism is specifically used for adjusting the size of an enclosing area enclosed by the reflecting mirrors so as to adjust the size and the direction of light spots on the incident light end face of the dodging cavity and/or the emergent light end face of the dodging cavity.

In the implementation mode, the size of the splicing area of the dodging cavity can be flexibly changed by depending on the dodging cavity adjusting mechanism, so that the direction and the size of the illumination light spots are correspondingly changed, the size and the direction of the illumination light spots are adjustable, and the illumination requirement of complex samples is improved.

Optionally, the apparatus comprises: the light spots formed by the plurality of the lighting branch structures coincide, and the plurality of the lighting branch structures are symmetrically arranged around the center of the light spot; the light source couples the emitted light to the incident light end face of the light homogenizing cavity in the plurality of illumination branch structures through a plurality of optical fiber output ends.

In the above implementation manner, by equally dividing the incident light provided by the light source to each illumination branch structure and through the light homogenizing effect of the light homogenizing cavity in each branch structure, the illumination uniformity reaching the sample surface can be improved from various angles.

In a second aspect, embodiments of the present application further provide a detection apparatus, where the apparatus includes: a detector and an illumination device as described in any one of the above; the illumination device is used for obliquely irradiating the sample, and the incident light of the obliquely irradiation has a non-zero included angle with the normal line of the sample; the detector is used for detecting signal light generated by the sample after oblique irradiation so as to detect the sample according to the signal light.

In the implementation manner, the uniformity of illumination light is improved by using the detector of the illumination device, so that the detection quality of the sample defects is improved.

Optionally, the apparatus further comprises: an objective table; the object stage is used for placing a sample to be detected, the detector is arranged opposite to the object stage, and the optical axis of the detector is perpendicular to the surface to be detected of the sample; the lighting device is used for: obliquely irradiating the sample placed on the object stage; the detector is also for: and collecting scattered light of the sample placed on the object stage after being obliquely irradiated by the illumination device, and carrying out imaging detection on the surface of the sample based on the scattered light.

In the implementation manner, the detection device of the dark field illumination device improves the uniformity of illumination light, so that the detection quality of the sample defects is improved.

Optionally, the first azimuth angle of the illumination branching structure is configured so that the outgoing light end face of the dodging cavity is conjugated with the sample surface.

In the implementation manner, the light emergent surface of the light homogenizing cavity of each lighting branch structure can be effectively projected on the sample in a conjugate manner by adjusting the first azimuth angle, so that the energy utilization rate is improved, a plurality of branch light paths can be more uniformly distributed to form annular lighting, and the uniformity of the annular lighting is improved.

Optionally, the second azimuth of the dodging cavity is configured such that the output light spot of each illumination branch structure received by the sample surface coincides.

In the above implementation manner, by adjusting the second azimuth angle, the emergent light spots of each branch illumination light path can be perfectly overlapped at the center of the sample, so that the illumination uniformity is improved, and the mechanism device with complex design is avoided to assist the eccentric adjustment.

In a third aspect, an embodiment of the present application further provides a detection method, where the method is applied to any one of the detection devices described above; the method comprises the following steps: illuminating a sample to be detected by adopting the illumination device; detecting signal light generated after the sample is irradiated so as to detect the sample.

In a fourth aspect, embodiments of the present application further provide an adjustment method, where the adjustment method is applied to any one of the detection devices described above; the method comprises the following steps: adjusting a first azimuth angle of an illumination branch structure in the illumination branch structure so as to enable an emergent light end face of the light homogenizing cavity to be conjugate with the surface of the sample; and adjusting a second azimuth angle of the light homogenizing cavity in the illumination branch structure so as to enable output light spots of each illumination branch structure received by the sample surface to coincide.

In a fifth aspect, an embodiment of the present application further provides a light source design method, where the method is applied to any one of the above-mentioned lighting devices, and the light source, the light homogenizing cavity, and the lighting lens group in the lighting branch structure are sequentially disposed along the light path; the method comprises the following steps: and acquiring the azimuth angle of the illumination branch structure so that the emergent light end face is subjected to conjugate imaging to the sample surface through the lens of the illumination lens group.

In the implementation mode, the azimuth angle of the illumination branch structure is adjusted, so that the design effect of light source illumination is achieved, and the design flexibility is improved.

Optionally, acquiring the azimuth angle of the dodging cavity includes: acquiring a first azimuth angle of the illumination branch structure so as to enable the emergent light end face of the light homogenizing cavity to be conjugate with the sample surface, wherein the first azimuth angle is an included angle of the emergent light end face of the light homogenizing cavity relative to the sample surface; wherein the first azimuth angle satisfies a relation: beta = δ×Μ; wherein, beta is the first azimuth angle, delta is the included angle between the light emitting direction of the light emitting end face of the light homogenizing cavity and the normal line of the sample surface, and M is the magnification of the projection lens of the illumination lens group.

Optionally, the light emergent end face of the light homogenizing cavity is rectangular, the plurality of lighting branch structures include a reference lighting branch structure, the incident light of the reference lighting branch structure has a reference incident face relative to the sample, and the image of the light spot extending direction on the light emergent end face of the light homogenizing cavity of the reference lighting branch structure has a reference extending direction; the design method further comprises the following steps: acquiring an image of the light spot extending direction on the light emitting end face of the light homogenizing cavity of the reference lighting branch structure to obtain a reference extending direction of the light emitting end face of the light homogenizing cavity; acquiring an azimuth angle of the illumination branch structure, wherein the azimuth angle comprises acquiring a second azimuth angle of the illumination branch structure, and the second azimuth angle is an included angle between an extending direction of an emergent light end surface of the light homogenizing cavity and the reference extending direction; acquiring a second azimuth angle of the illumination branch structure, comprising: acquiring an included angle between an incident surface of the illumination branch structure relative to a sample and the reference incident surface; and obtaining a second azimuth angle according to a formula gamma=theta/M, wherein gamma is the second azimuth angle, M is the magnification of the projection lens of the illumination lens group, and theta is the included angle between the incident light of the illumination branch structure relative to the incident surface of the sample and the reference incident surface.

Optionally, acquiring the second azimuth of the illumination branch structure further comprises: and acquiring the direction of the second azimuth angle of the illumination branch structure according to the principle of the Mr imaging.

In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a lighting device according to an embodiment of the present disclosure;

fig. 2 is a schematic view of an illumination device with multiple illumination branch structures according to an embodiment of the present application;

FIG. 3 is a schematic view of a first azimuth angle provided in an embodiment of the present application;

FIG. 4 is a schematic view of a second azimuth angle provided in an embodiment of the present application;

fig. 5 is a schematic view of a third azimuth angle provided in an embodiment of the present application;

Fig. 6 is a schematic adjustment diagram of a dodging cavity adjustment mechanism according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of a linking of a light source and four lighting branch structures according to an embodiment of the present disclosure;

fig. 8 is a schematic diagram of a detection device according to an embodiment of the present application;

fig. 9 is a light spot intensity distribution diagram of four illumination branch structures according to an embodiment of the present application;

fig. 10 is an imaging light spot diagram of four illumination branch structures provided in an embodiment of the present application.

Icon: 10-sample; 20-an illumination branch structure; 21-a light source; 22-a light homogenizing cavity; 23-illumination lens group; 24-turning mirrors; 25-a dodging cavity adjusting mechanism.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Also, in the description of the present application, the terms "first," "second," and the like are used merely to distinguish one from another and are not to be construed as indicating or implying any actual such relationship or order between such entities or operations. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

In the description of the present application, it should be noted that, the terms "upper," "lower," "inner," "outer," and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or an azimuth or a positional relationship commonly visited when the inventive product is used, only for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and therefore should not be interpreted as a limitation of the present application.

In the description of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; the connection may be direct or indirect via an intermediate medium, or may be internal communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.

Before describing the embodiments of the present application, a brief description will be first made of technical concepts related to the present application.

Machine vision illumination: the illumination condition has key influence on actual imaging, is subject to the size, material and characteristic difference of product detection, is difficult to adapt to various detection scenes by a single light source, most of light sources of a machine vision system are non-standard and customized, and the light source is selected to take a polishing mode into consideration except the most basic shape, color and other properties. The light source incident angle is distinguished, and common lighting modes are bright field lighting, dark field lighting and backlight. The backlight is a means of illumination from the bottom of the object, which is very effective for edge detection. Under the lighting mode of bright field illumination, the light source directly irradiates the surface of an object, the incident angle is 45-90 degrees, namely high-angle irradiation, and a large amount of reflected light can be received in a lens after the light source directly irradiates the surface of the object, so that the common bright field illumination is not suitable for the object with a mirror surface. Dark field illumination is a mode of illuminating an object from a low angle by a light source, and the illumination direction is smaller than 45 degrees, so that reflected light of a smooth surface can be illuminated to the periphery and cannot reach a lens, thereby forming darker imaging in the lens, and the angle of the reflected light is larger at a place with a concave or convex part, and more reflected light can enter the lens, so that brighter imaging is generated.

Conjugation: in the physical extremum problem, when one physical quantity (y) can take a maximum value or a minimum value and the other physical quantity (x) related to the maximum value is increased, y is a non-monotonic function (physical meaning) of x. When the physical quantity y is equal to a certain value other than the extremum, the physical quantity x may take two different values corresponding thereto, and when the sum or product of the two different values is a constant value, this phenomenon is called a conjugate phenomenon. There is also a concept of a conjugate physical quantity in physics-a physical quantity having an indefinite relationship is called a conjugate physical quantity, such as: angular momentum and angle are a pair of conjugate physical quantities in quantum mechanics.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an illumination device according to an embodiment of the present disclosure. The device comprises: an illumination branching structure 20; the lighting branch structure 20 includes: a light source 21, a light homogenizing cavity 22 and an illumination lens group 23;

the dodging chamber 22 includes: an incident light end face, a cavity and an emergent light end face; the incident light end face and the emergent light end face are arranged at two ends of the cavity; the light source 21 is arranged on one side of the incident light end face; the illumination lens group 23 is arranged on one side of the emergent light end surface, and the illumination lens group 23 enables the emergent light end surface to be conjugate with the surface of the sample 10; wherein, the light source 21 in the illumination branch structure 20 is used for providing incident light, the light homogenizing cavity 22 is used for receiving the incident light and irradiating the incident light to the illumination lens group 23, and the illumination lens group 23 is used for obliquely irradiating the sample 10 based on the incident light; the azimuth angle of the illumination branch structure 20 is configured such that the outgoing light end face is conjugated imaged to the surface of the sample 10 via the lens of the illumination lens group 23.

Illustratively, the lighting branching structure 20 may be: a plurality of branch light paths for lighting and illuminating the sample 10 (such as a wafer or a wafer) to be tested, if a plurality of lighting branch structures 20 exist, each branch light path can illuminate the sample 10 at a certain incident angle, and the plurality of branch light paths can further form annular illumination; each of the branched optical paths may include a light source 21 for providing illumination light, a dodging cavity 22 for adjusting illumination direction and brightness, and an illumination lens group 23 for direct illumination, and the illumination light provided by the light source 21 is sequentially irradiated onto the sample 10 through the dodging cavity 22 structure and the illumination lens group 23 (e.g., critical illumination structure). The light homogenizing chamber 22 may be: the reflective cavity structure consisting of the incident light end face, the light homogenizing cavity 22 and the emergent light end face can be formed by a plurality of (for example, four) reflecting mirror surfaces, or can be a reflecting cavity formed by integral processing.

Alternatively, the sample 10 is described by way of example as a wafer. An exemplary view of the light emitted by a single illumination branch structure 20 illuminating the wafer surface is shown in fig. 1, as shown in fig. 2, two illumination branch structures Z1, Z2 obliquely illuminate the wafer surface placed on a motion platform (motion module), and the light scattered by the wafer is collected and processed by a data processing center in a detection module C1 directly above, and the illumination branch structure 20 of fig. 1 can be regarded as the illumination branch structure Z1 on the left side in fig. 2. Each of the illumination branch structures 20 includes: the light source 21, the dodging cavity 22 and the critical illumination structure (the illumination lens group 23) can be circumferentially distributed around the center of the wafer by the plurality of illumination branch structures 20, so that multi-angle and omnibearing illumination of the wafer in a dark field is realized. The light source 21 may be a broadband light source 21, a laser light source 21, or the like, the light source 21 may be disposed at any position on the incident light end surface side of the light homogenizing chamber 22, the illumination lens group 23 may be disposed at any position on the emergent light end surface side of the light homogenizing chamber 22, the illumination lens group 23 may conjugate the emergent light end surface with the surface of the sample 10, and the emergent light end surface may be conjugated and imaged onto the surface of the sample 10 through the lens of the illumination lens group 23 by configuring the azimuth angle of the illumination branch structure 20. Specifically, the position of the light homogenizing cavity 22 and the azimuth angle related to the light emitting surface can be configured, so that the irradiation light provided by the light source 21 is homogenized in a targeted manner, the light beam is incident to the entrance of the light homogenizing cavity 22, and the light emitting surface of the light homogenizing cavity 22 is conjugated with the surface of the sample 10 through the illumination lens group 23. The light source 21 emits light, and after entering the light homogenizing cavity 22, the light is uniformly diffused to the emergent light end face of the illumination lens group 23 through the actions of multiple reflection, refraction, scattering and the like in the light homogenizing cavity 22, so that uniform illumination of a wafer is realized, meanwhile, the illumination power density can be improved, and stray light is well inhibited.

The light on the surface of the wafer is conjugate light, namely the angle of incidence of the light on the surface of the wafer is equal to the angle of reflection of the light from the surface of the wafer; the conjugation principle based on the method is the principle of imaging the poloxamer, namely: the object plane (wafer), the film plane (rear group part) and the lens plane (front group part) are converged at an imaginary point below the camera, and the three planes intersect at one point, so that the wafer can obtain the maximum clear range. Meanwhile, the light homogenizing cavity 22 can separate the light source 21 from the illumination lens group 23, so that the illumination direction and the illumination brightness can be conveniently adjusted.

Through setting up illumination branch structure 20, this illumination branch structure 20 includes structures such as light source 21, even optical cavity 22 and illumination mirror group 23, even optical cavity 22 comprises the cavity that one end is the incident light terminal surface, the other end is the emergent light terminal surface, light source 21 sets up in incident light terminal surface one side, illumination mirror group 23 sets up in emergent light terminal surface one side, dispose the azimuth of illumination branch structure 20, make emergent light terminal surface and sample 10 surface conjugation, even make even optical cavity 22 play plain noodles through illumination mirror group 23 after effectively conjugate projection on sample 10 surface, and then make the energy utilization of light source 21 obtain improving, the homogeneity of illumination has been improved, illumination power density has been improved.

In one embodiment, the azimuth angle of the illuminating branched structure 20 includes: a first azimuth angle; the first azimuth angle is the included angle of the emergent light end surface of the light homogenizing cavity 22 relative to the surface of the sample 10; the first azimuth angle satisfies the relation: beta = δ×Μ; where β is a first azimuth angle, δ is an angle between the light emitting direction of the light emitting end face of the light homogenizing cavity 22 and the normal line of the surface of the sample 10, and M is the magnification of the projection lens of the illumination lens group 23.

Illustratively, as shown in fig. 3, the position of the light homogenizing cavity 22 in the illumination branching structure 20 and the azimuth angle related to the light exit surface are configured such that the light exit of the light homogenizing cavity 22 is conjugated to the wafer surface. The azimuth angle of the configuration may include a first azimuth angle, that is, an angle between the outgoing light end surface of the dodging cavity 22 and the wafer surface. For example, a coordinate system may be established for specific explanation, in the three-dimensional coordinate system of the XYZ axis established on the light-emitting surface of the light-homogenizing cavity 22 with the center of the wafer surface as the origin of the coordinate axis, the wafer surface as the XY plane, and the direction of the light-homogenizing cavity 22 as the Z axis, then the first azimuth angle may be considered as an included angle between the light-emitting end surface of the light-homogenizing cavity 22 and the XY plane in the coordinate system, and may represent an inclination angle of the spatial distribution position of the light-emitting end surface of the light-homogenizing cavity 22 of each of the plurality of lighting branch structures 20.

The first azimuth angle may be denoted as β, and the specific configuration may satisfy the following relation: beta = δ×Μ; wherein delta is the included angle between the light emitting direction of the light emitting end face of the light homogenizing cavity 22 and the normal line of the surface of the sample 10, and M is the magnification of the projection lens of the illumination lens group 23. Since the principle of the imaging of the Moire refers to that when light is reflected from one plane to another, if the normal directions of the two planes are the same, the reflected light is conjugated with the incident light. When the first azimuth design of the illumination branch structure 20 satisfies the above relation, the light outlet of the light homogenizing cavity 22 is conjugated with the wafer surface, and the light is directly irradiated from the light outlet of the light homogenizing cavity 22 to the wafer surface, and the incident light is conjugated with the reflected light. In a certain error range, the spatial inclination angle (first azimuth angle) of the light emitting surface of the light homogenizing cavity 22 is reasonably set, so that the included angle between the spatial distribution position of the light emitting end surface of the light homogenizing cavity 22 and the plane of the sample 10 can be kept in a reasonable range for improving illumination uniformity, the light emitting surface of the light homogenizing cavity 22 can be effectively and conjugate projected on the surface of the sample 10, the energy utilization rate is improved, and the illumination uniformity of the annular illumination branch structure 20 is improved.

Through reasonable error range design of the first azimuth angle meeting the preset relational condition, a plurality of branch light paths can be more uniformly distributed and surrounded into annular illumination, and the uniformity of the annular illumination is improved; the light-emitting surface of the light homogenizing cavity 22 can be effectively projected on the sample 10 in a conjugate manner, so that the energy utilization rate is improved.

In one embodiment, the apparatus comprises: a plurality of illumination branch structures 20; the light emergent end face of the light homogenizing cavity 22 is rectangular, the plurality of illumination branch structures 20 comprise reference illumination branch structures 20, incident light of the reference illumination branch structures 20 has a reference incident surface relative to the sample 10, an image of the light emergent end face of the light homogenizing cavity 22 of the reference illumination branch structures 20 in the light spot extending direction has a reference extending direction, and the light emergent end face of the light homogenizing cavity 22 is along the reference extending direction; the azimuth angle of the illuminating branched structure 20 further includes: a second azimuth angle; the second azimuth angle is an included angle between the extending direction of the emergent light end face of the light homogenizing cavity 22 and the reference extending direction; the second azimuth satisfies the relationship: γ=θ/M; where γ is the second azimuth angle, M is the magnification of the projection lens of the illumination lens group 23, and θ is the angle between the incident light illuminating the branching structure 20 and the reference incident plane with respect to the incident plane of the sample 10.

Illustratively, as shown in FIG. 4, a schematic view of an imaging spot illuminated on the surface of the sample 10 by two illumination branching structures 20 (the dodging chamber 22 is represented by a small rectangular box and the illumination optics 23 is represented by a large rectangular box) is shown. The reference illumination branch structure 20 may be the illumination branch structure 20 in fig. 4 in which the outgoing light end surface of the dodging cavity 22 is perpendicular to the optical axis direction of the illumination lens group 23, that is, the illumination branch structure 20 positioned in line with the upper optical axis, and since the outgoing light end surface of the dodging cavity 22 is rectangular, the reference incident surface may be regarded as: when the rectangular long side of the light emitting end surface of the light homogenizing cavity 22 is perpendicular to the optical axis direction of the illumination lens group 23, the light is projected onto the imaging surface of the sample 10, as a in fig. 4, and at this time, the light emitted from the light emitting end surface of the light homogenizing cavity 22 is regarded as being transmitted along the reference extending direction, and the imaging light spot on the surface of the sample 10 is a. The azimuth angle related to the light emitting surface of the light homogenizing cavity 22 in the illumination branch structure 20 is configured so that the light emitting opening of the light homogenizing cavity 22 is conjugated with the surface of the sample 10. Wherein the configured azimuth may include a second azimuth, which may be: the angle between the extending direction of the outgoing light end surface of the light equalizing cavity 22 and the reference extending direction, that is, the angle at which the rectangular long side of the outgoing light end surface rotates with respect to the optical axis direction of the perpendicular illumination mirror group 23.

The second azimuth may be denoted as γ, and its specific configuration may satisfy the following relation: γ=θ/M; where M is the magnification of the projection lens of the illumination lens group 23, and θ is the angle between the incident light of the illumination branch structure 20 and the reference incident plane with respect to the incident plane of the sample 10. As shown in fig. 4, when the rectangular long side of the light exit surface of the light homogenizing cavity 22 in the illumination branching structure 20 is rotated by an angle γ with respect to the direction perpendicular to the optical axis of the illumination lens group 23, that is, the illumination branching structure 20 located at the lower position, the imaging spot on the surface of the sample 10 is correspondingly rotated by an angle θ with respect to the reference imaging plane a (or the imaging spot a), that is, the imaging spot b.

For example, a coordinate system may be established for specific explanation, in the light-emitting surface of the light-homogenizing cavity 22, an XY two-dimensional coordinate system is established with the center of the light-emitting end surface of the light-homogenizing cavity 22 as an origin and the direction perpendicular to the light-emitting end surface as the X-axis direction, and the second azimuth angle is an angle between the long side of the light-homogenizing cavity 22 and the X-axis, which may represent a spatial inclination angle of the long side of the light-emitting end surface of the light-homogenizing cavity 22 of each of the plurality of lighting branch structures 20. In a certain error range, the long-side space inclination angle (second azimuth angle) of the light emergent surface of the light homogenizing cavity 22 is reasonably set, and the light emergent surface light spots of the light emergent end surface of the light homogenizing cavity 22 can be effectively conjugate projected on the surface of the sample 10 by matching with the design of the first azimuth angle, so that the energy utilization rate is improved, and the illumination uniformity of the annular illumination branch structure 20 is improved.

Through reasonable error range design of the second azimuth angle meeting the preset relation condition, a plurality of branch light paths can be more uniformly distributed to form annular illumination, and the uniformity of the annular illumination is improved; the perfect overlapping of the emergent light spots of each branch illumination light path in the center of the sample 10 can be realized, the illumination uniformity is improved, and the mechanism device with complex design is avoided to assist the eccentric adjustment.

In one embodiment, the reference plane of incidence coincides with or is perpendicular to the direction of the spot extension.

Illustratively, the reference incidence plane may be: the rectangular long side of the light emitting end face of the light homogenizing cavity 22 is projected on the imaging surface of the sample 10 when being perpendicular to the optical axis direction of the illumination mirror group 23, as shown in a in fig. 4, the emitted light of the light emitting end face of the light homogenizing cavity 22 is transmitted along the reference extending direction, the imaging light spot on the surface of the sample 10 is a, the imaging light spot is just at the center of the sample 10, if the emitted light of all the illumination branch structures 20 is projected along the reference extending direction, the light spot extending direction coincides with the reference incident surface, and the effect that a plurality of light spots vertically overlap at the center of the sample 10 can be achieved by the light homogenizing cavity 22 without adjusting the second azimuth angle. If the outgoing light of the illumination branch structure 20 does not project along the reference extending direction, but projects along the direction perpendicular to the reference extending direction, the light spot extending direction is perpendicular to the reference incident plane, and the second azimuth angle corresponding to the light homogenizing cavity 22 at this time is just 90 °, so that the effect that a plurality of light spots transversely overlap at the center of the sample 10 can be achieved.

In one embodiment, the illumination branch structures 20 are uniformly distributed around the sample 10 centered on the sample 10.

For example, if the illumination device includes a plurality of illumination branch structures 20, the illumination branch structures 20 may be centered on the sample 10 and symmetrically disposed around the sample 10, so as to form a symmetrical and uniform annular illumination when the sample 10 is illuminated. The number of the branch structures can be more than 2, 3, 6, 8, 12, 16 and the like, and the branch light paths can be uniformly distributed along the circumferential direction of the sample 10, so that the arrangement can meet the detection requirement of the surface defects of the sample 10 and reduce the cost.

In one embodiment, the azimuth angle of the illumination branch structure 20 further comprises: a third azimuth angle; the third azimuth angle is an included angle of projection of the optical axis of the adjacent two illumination branch structures 20 in the plurality of illumination branch structures 20 on the surface of the sample 10; the third azimuth angle satisfies the relation: α=2pi/n; where n is the number of the plurality of illumination branch structures 20.

Illustratively, as shown in fig. 5, the third azimuth angle may be an included angle α of projection of the optical axes of each adjacent two of the four illumination branch structures 20 on the surface of the sample 10 in a top view of the wafer surface (indicated by the circular area) of the four illumination branch structures Z1, Z2, Z3, Z4 (indicated by the four black columns). The azimuth angle related to the position of the dodging cavity 22 in the illumination branch structure 20 is configured, so that the light outlet of the dodging cavity 22 is further conjugated with the surface of the wafer, wherein the configured azimuth angle can include a third azimuth angle, that is, an included angle of projection of the optical axes of two adjacent illumination branch structures 20 on the surface of the sample 10. For a specific explanation, a coordinate system may be established, in the three-dimensional coordinate system of the light-emitting surface of the light-homogenizing cavity 22, which is established by taking the center of the surface of the wafer as the origin of the coordinate axis, the surface of the wafer as the XY plane, and the direction of the light-homogenizing cavity 22 as the direction of the Z axis, the third azimuth angle may be an included angle between a line formed by connecting the center of the light-homogenizing cavity 22 and the center of the coordinate axis and the X axis in the coordinate system, which may represent an included angle of the spatial distribution position of the whole cavity of the light-homogenizing cavity 22 of each two adjacent lighting branch structures 20.

The third azimuth angle may be denoted as α, and its specific configuration may satisfy the following relation: α=2pi/n; where n is the number of the plurality of illumination branch structures 20. Within a certain error range, the included angle (third azimuth angle) of the spatial distribution position of the cavity of the light homogenizing cavity 22 is reasonably set, so that the spatial distribution position of the cavity of the light homogenizing cavity 22 and the surface of the sample 10 are kept in a reasonable range for improving illumination uniformity, and the light emergent surface of the light homogenizing cavity 22 can be effectively conjugated and projected on the surface of the sample 10 by further matching with other azimuth designs, so that the energy utilization rate is improved, and the illumination uniformity of the annular illumination branch structure 20 is improved.

The relative spatial distribution positions of the plurality of lighting branch structures 20 can be controlled through reasonable error range design of the third azimuth angle meeting the preset relational expression condition, so that the spatial uniformity of annular lighting is improved; the plurality of branch light paths can be more uniformly distributed to form annular illumination, and the uniformity of the annular illumination is improved.

In one embodiment, the lighting branching structure 20 further comprises: and a turning mirror 24 located between the light homogenizing cavity 22 and the sample 10, for changing the direction of the light rays emitted from the light emitting end face of the light homogenizing cavity 22.

Illustratively, the turning mirror 24 may be an optical element for changing the propagation direction of light, and may generally consist of a reflective surface and a curved transparent base; the light is deflected by the reflecting surface so that the light changes its propagation direction without changing its wavefront shape. Optionally, a turning mirror 24 disposed on the light exit end face side of the light homogenizing cavity 22 is used to change the propagation direction of the light reflected to the illumination lens group 23, so as to reduce the volume of the whole device. By configuring the azimuth angle of the light homogenizing chamber 22, adjusting the position and angle of the turning mirror 24, and matching with the proper magnification of the illumination lens group 23, a large working distance can be realized and the conjugated relation between the surface of the sample 10 and the chamber of the light homogenizing chamber 22 can be maintained. When the incident light passes through the outgoing light end face of the light homogenizing cavity 22 and is reflected by the turning mirror 24, the propagation direction of the light can be changed, and the refraction degree and direction of the light can be controlled by adjusting the position and angle of the turning mirror 24, so that good spot uniformity during illumination is realized.

In one embodiment, the turning mirror 24 is disposed between the outgoing light end surface of the dodging cavity 22 and the illumination lens group 23; or between the illumination lens group 23 and the sample 10.

Illustratively, a turning mirror 24 may be disposed between the light-emitting end surface of the light-homogenizing cavity 22 and the illumination lens group 23, so as to turn the light outputted from the light-homogenizing cavity 22 to the entrance of the illumination lens group 23, so that the light from the light source 21 can be emitted and turned by the turning mirror 24 through the light-homogenizing cavity 22 to be guided to the illumination lens group 23, and the light transmitted by the illumination lens group 23 irradiates the surface of the sample 10, thereby realizing a more compact light path design. The turning mirror 24 may also be disposed between the illumination lens set 23 and the sample 10, so as to turn the light emitted from the illumination lens set 23 to the surface of the sample 10, so that the light from the light source 21 may be emitted from the light homogenizing cavity 22 through the turning mirror 24, transmitted by the illumination lens set 23, and redirected to the surface of the sample 10, thereby realizing a more compact light path design.

In one embodiment, the illumination lens group 23 includes: a first lens and a second lens; the first lens is arranged on one side close to the emergent light end face of the light homogenizing cavity 22, and the second lens is arranged on one side close to the sample 10; the turning mirror 24 is disposed between the first lens and the second lens, and is used for deflecting the outgoing light beam passing through the first lens from the light homogenizing chamber 22 from a vertical direction perpendicular to the surface of the sample 10 to an oblique direction relative to the surface of the sample 10, so that the outgoing light beam passes through the second lens and then is obliquely irradiated on the surface of the sample 10.

For example, with continued reference to fig. 1 or 2, the first and second lenses (two cylinders in the illumination lens group 23 of fig. 1 or 2) may be: a condenser lens or an objective lens in the critical illumination structure (the illumination lens group 23) can image the light source 21 onto the observed object plane, has high brightness and concentrated illumination effect, and the objective lens can amplify the image on the object plane and transmit the image to the microscope system (the detection module in fig. 2) for observation, and if other illumination structures are used in the illumination lens group 23, the structures of the two lenses can be adaptively adjusted. Therefore, the first lens disposed near the light exit end face of the light homogenizing chamber 22 may be regarded as a condenser lens, the second lens disposed near the sample 10 side may be regarded as an objective lens, and the turning mirror 24 is disposed between the condenser lens and the objective lens, and since the turning mirror 24 has an effect of changing the transmission direction of the light, the light is not transmitted in the original transmission direction (vertical direction in fig. 1 or 2) after exiting through the light homogenizing chamber 22, is purposefully deflected to the entrance of the objective lens in the lateral direction by the turning mirror 24, and is irradiated onto the surface of the sample 10 through the objective lens. If the turning mirror 24 is not provided, the light rays are transmitted along the original transmission direction after exiting from the light homogenizing cavity 22, and then the objective lens must be disposed at a linear position along the original transmission direction, so that the lateral dimension of the illumination branch structure 20 is increased, the whole space is increased, the use is inconvenient, and the manufacturing cost is also increased.

By arranging the turning mirror 24 in the lens light path of the illumination lens group 23, the light path is turned, the size of the transverse light path is reduced, the space volume of the illumination branching structure 20 is saved, and the manufacturing cost is reduced.

In one embodiment, the lighting branching structure 20 further comprises: and the dodging cavity adjusting mechanism 25 is used for adjusting the light spot size and direction of the light at the incident light end surface of the dodging cavity 22 and/or the light spot size and direction of the light at the emergent light end surface of the dodging cavity 22.

Illustratively, the dodging cavity adjustment mechanism 25 may be: and an optical element for adjusting the light distribution and intensity in the light homogenizing cavity 22 to realize the control of the optical characteristics such as the intensity, uniformity, beam quality and the like of the emergent light end face. The dodging cavity adjusting mechanism 25 may comprise an adjuster, a driving device and a control unit, wherein the adjuster may be composed of a series of lenses, a reflecting mirror, an adjustable diaphragm and the like, and may change the propagation path of the light in the dodging cavity 22 so as to realize adjustment of light distribution and light intensity; the driving device can be composed of a motor, a manual adjusting knob or other driving sources, and can push the regulator to move along the optical axis direction or change the inclination angle of the regulator in the optical axis direction; the control unit can be composed of a microprocessor, a controller, a sensor and the like, and the position and the posture of the regulator are regulated by the driving device according to a preset regulation program and optical information fed back by the sensor so as to realize accurate control of optical characteristics. When light enters the light homogenizing cavity 22, the regulator can reflect, refract, scatter and the like the light to realize the regulation of light distribution and light intensity. The actuator is movable along the optical axis direction or the inclination angle in the optical axis direction is changed by the driving means. The control unit precisely controls the position and the posture of the regulator according to a preset regulating program and optical information fed back by the sensor so as to realize the control of the optical characteristics such as the light intensity, the uniformity, the light beam quality and the like of the incident light end face and/or the emergent light end face.

Through the design of the dodging cavity adjusting mechanism 25, the adjustment of the size and the direction of the light spot can be realized under the condition that the structure of the whole dodging cavity 22 is not changed, and the illumination requirement of a complex sample is improved.

In one embodiment, the dodging cavity adjustment mechanism 25 is disposed outside the incident light end face and/or outside the exit light end face of the dodging cavity 22.

For example, with continued reference to fig. 1 or 2, a dodging cavity adjustment mechanism 25 may be provided on either side or sides of the dodging cavity 22 to enable flexible adjustment of the azimuth angle of the dodging cavity 22. An adjuster, which may be one or more optical elements such as lenses, mirrors, etc., is provided outside the light-incident and/or light-exiting end surfaces of the cavity of the light-homogenizing cavity 22. The regulator can regulate the direction of the incident light and/or the emergent light, the size and shape of the light beam and the like so as to realize the control of the optical characteristics of the emergent light end face, such as the light intensity, the uniformity, the light beam quality and the like. The actuator may be moved by a driving means, such as a motor drive, a manual adjustment knob, etc., to achieve precise control of the optical properties. The control unit may detect characteristics of the incident light and/or the outgoing light by means of a sensor and feed back the detected signals to the regulator for an adaptive adjustment of the optical characteristics. By arranging the dodging cavity adjusting mechanism 25 on any one side or multiple sides of the dodging cavity 22, flexible adjustment of the azimuth angle of the dodging cavity 22 is realized, and the illumination requirement of a complex sample is improved.

In one embodiment, the dodging cavity 22 is a reflective cavity structure formed by splicing and enclosing mirrors, and the dodging cavity adjusting mechanism 25 is specifically configured to adjust the size of an enclosing area enclosed by the mirrors, so as to adjust the size and direction of a light spot on an incident light end surface of the dodging cavity 22 and/or an emergent light end surface of the dodging cavity 22.

Illustratively, the structure of the light homogenizing chamber 22, which is a reflective light homogenizing chamber 22 formed by an incident light end face, a light homogenizing chamber 22 body and an emergent light end face, may be specifically a reflective chamber body formed by splicing a plurality of reflective mirror surfaces (for example, four reflective mirror surfaces), as shown in fig. 6, which is a cross-sectional view of the light homogenizing chamber 22 formed by four reflective mirror surfaces. The splice area may be: a closed area surrounded by a plurality of reflecting mirrors, such as an inner area surrounded by four rectangular blocks in fig. 6. The dodging cavity adjusting mechanism 25 can be arranged on the side edge of one or two reflecting mirrors of the dodging cavity 22, and the size of the spliced area can be adjusted by changing the interval distance or the relative position between the two reflecting mirrors which are oppositely arranged, so that the size of the light spot can be changed by changing the size of the spliced area of the dodging cavity 22, and the direction of the light spot can be changed. According to the actual illumination requirement, the size of the splicing area can be flexibly changed by depending on the light homogenizing cavity adjusting mechanism 25 under the condition that the structure of the whole light homogenizing cavity 22 is not changed, so that the direction and the size of the illumination light spots are correspondingly changed, the size and the direction of the illumination light spots are adjustable, and the illumination requirement of complex samples is improved more favorably.

In one embodiment, the apparatus comprises: the light spots formed by the plurality of illumination branch structures 20 coincide, and the plurality of illumination branch structures 20 are symmetrically arranged around the center of the light spot; the light source 21 couples the emitted light through a plurality of fiber outputs to the incident light end face of the light homogenizing cavity 22 in the plurality of illumination branching structures 20.

Illustratively, the plurality of illumination branch structures 20 may be centered on the sample 10 and symmetrically disposed around the center of the sample 10, so as to form a symmetrical and uniform annular illumination when the sample 10 is illuminated, and the azimuth angle of the light homogenizing cavity 22 is adjusted when the sample 10 is illuminated, so that the imaging light spots formed by the plurality of illumination branch structures 20 on the surface of the sample 10 coincide. As shown in fig. 7, the connection structure between the light source 21 input end of the four illumination branch structures 20 and the xenon lamp light source 21 is shown, the xenon lamp light source 21 is coupled by the 1-split 4-beam-combining optical fibers and equally divided into 4 branch optical fibers, and the output ends Z11, Z21, Z31, Z41 of the branch optical fibers can be directly coupled with the incident light end surfaces of the light homogenizing cavities 22 of the four illumination branch structures Z1, Z2, Z3, Z4, so as to equally divide the incident light generated by the light source 21 into the four illumination branch structures 20.

By equally dividing the incident light provided by the light source 21 to each of the illumination branch structures 20, the uniformity of illumination reaching the surface of the sample 10 can be improved from various angles by the light homogenizing action of the light homogenizing cavities 22 in each branch structure.

In addition, the embodiment of the application also provides a detection device, which comprises: a detector and an illumination device of any of the embodiments described above; the illumination device is used for obliquely irradiating the sample 10, and incident light of the obliquely irradiation has a non-zero included angle with the normal line of the sample 10; the detector is used for detecting signal light generated by the sample 10 after oblique irradiation so as to detect the sample 10 according to the signal light.

Illustratively, the detector may be: the optical signal is converted into an electrical signal for detection, such as a photoelectric detector and a dark field detection device such as a microscope, a telescope, a video camera, a scanning tunnel microscope, etc., wherein the photoelectric detector can utilize radiation to cause the conductivity of the material of the irradiated sample 10 to change, and the photoelectric detector can be divided into: photon detectors and heat detectors. Electrons in the photon detector directly absorb photon energy, and change the motion state to generate an electrical signal for detecting infrared radiation or visible light generated by non-perpendicular irradiation of the surface of the sample 10 by the illumination device. The thermal detector is an infrared detector working by using thermal effect, and can be composed of a thermosensitive element and a measuring circuit, wherein the measuring circuit can be used for measuring the resistance value or voltage value of the thermosensitive element and converting the resistance value or voltage value into a readable electric signal by using the thermal property of the surface material of the sample 10 after being irradiated by the illumination device in a non-vertical mode. By using the detector of the illumination device, the uniformity of illumination light is improved, thereby improving the detection quality of defects of the sample 10.

In one embodiment, the apparatus further comprises: an objective table; the objective table is used for placing a sample 10 to be detected, the detector is arranged opposite to the objective table, and the optical axis of the detector is perpendicular to the surface to be detected of the sample 10; the lighting device is used for: obliquely irradiating the sample 10 placed on the object stage; the detector is also for: and collecting scattered light after the sample 10 placed on the object stage is obliquely irradiated by the lighting device, and carrying out imaging detection on the surface of the sample 10 based on the scattered light.

The device may be, for example, a microscope, a telescope, a camera, a scanning tunnel microscope, or the like, for generating a dark field detection image of the surface of the sample 10, and the device generates a detection image corresponding to the dark field detection in a dark field illumination lighting manner. Referring to fig. 2, the dark field detection apparatus may include: an imaging detection assembly (detection module or detector) and a dark field illumination device. The dark field illumination device may be any of the illumination devices in the foregoing embodiments, where the illumination branch structure 20 in the illumination device provides uniform illumination light, and a plurality of illumination branch structures 20 may be disposed to annularly illuminate the sample 10 placed in the central area, and the imaging detection assembly may specifically be composed of an imaging objective lens and an imaging CCD sensor, and disposed opposite to the sample 10, for detecting defect features such as depressions, protrusions, scratches, and the like on the surface of the sample 10. If there are defective features on the surface of the sample 10, some of the light diffusely reflected from the defective features may enter the objective lens for imaging, and these defective features are reflected in bright images in dark fields of view, which may ultimately be present in a CCD.

Alternatively, as shown in fig. 8, a detection module of a dark field detection device is shown, which may be composed of a light source 21 module, a movement module, a lighting device, a detection module, and a data processing center. The light source 21 module consists of xenon lamp light sources 21+1 split 4 combined optical fibers, and provides an input light source 21 for the light homogenizing cavities 22 of each branch; the motion module consists of an XYZ motion platform which comprises a platform for adsorbing wafers; the lighting device (e.g. consisting of four lighting branch structures Z1, Z2, Z3, Z4) comprises: the four optical fiber incidence ends (Z11, Z21, Z31 and Z41) corresponding to the light source 21 modules, the dodging cavity 22, the dodging cavity adjusting mechanism 25, the front illumination lens group, the reflecting mirror and the rear illumination lens group; the detection module is used for collecting dark field scattering signals, guiding the dark field scattering signals to a camera for imaging to acquire physical information of a measured object, and uploading the physical information to the data processing center, wherein the main components can comprise a nose wheel objective lens system (C13), a tube lens (C12) and a camera; the data processing center (C11) is used for collecting signals of the detected object, judging the detected object through analysis of a later algorithm and acquiring defect characteristics.

By using the detection device of the dark field illumination device, the uniformity of illumination light is improved, thereby improving the detection quality of the defects of the sample 10.

In one embodiment, the first azimuthal angle of the illumination branching structure 20 is configured such that the exit light end face of the light homogenizing chamber 22 is conjugated to the surface of the sample 10.

Illustratively, as shown in fig. 9, the light intensity distribution diagram of the light spots generated by the four illumination branch structures 20 illuminating the surface of the sample 10 before and after conjugation is shown, and the first azimuth angle β, that is, the included angle of the outgoing light end surface of the light homogenizing cavity 22 with respect to the wafer surface, is configured, and the inclination angle of the spatially distributed position of the outgoing light end surface of the light homogenizing cavity 22 of each illumination branch structure 20. Since the first azimuth angle β can satisfy the following relation when the illumination branch structure 20 is provided: beta = δ×Μ; wherein delta is the included angle between the light emitting direction of the light emitting end face of the light homogenizing cavity 22 and the normal line of the surface of the sample 10, and M is the magnification of the projection lens of the illumination lens group 23. In a certain light difference range, the included angle beta of the emergent light end surface of the light homogenizing cavity 22 relative to the surface of the wafer is slowly adjusted, namely, the space inclination angle of the emergent light surface of the light homogenizing cavity 22 is adjusted, so that the first azimuth angle of the illumination branch structure 20 can be adjusted to be approximately or just to meet the above relation, the light outlet of the light homogenizing cavity 22 is approximately conjugated or just conjugated with the surface of the wafer, light directly irradiates the surface of the wafer from the light outlet of the light homogenizing cavity 22, the incident light is conjugated with the reflected light, the light spot intensity generated by the irradiation of the sample 10 by the four illumination branch structures 20 gradually approaches average, the energy utilization rate is improved, and the illumination uniformity of the annular illumination branch structure 20 is further improved.

By adjusting the first azimuth angle, the light-emitting surface of the light homogenizing cavity 22 of each lighting branch structure 20 can be effectively projected on the sample 10 in a conjugate manner, so that the energy utilization rate is improved, a plurality of branch light paths can be more uniformly distributed to form annular lighting, and the uniformity of the annular lighting is improved.

In one embodiment, the second azimuthal angle of the light homogenizing chamber 22 is configured such that the output spot of each illumination branching structure 20 received by the surface of the sample 10 coincides.

Illustratively, as shown in fig. 10, the imaging distribution diagram of the light spot generated by the four illumination branch structures 20 illuminating the surface of the sample 10 before and after adjustment is shown, and the second azimuth angle γ, that is, the angle between the extending direction of the outgoing light end surface of the dodging cavity 22 and the reference extending direction, that is, the angle at which the rectangular long side of the outgoing light end surface rotates with respect to the optical axis direction of the perpendicular illumination lens group 23 is configured. Since the second azimuth angle γ can satisfy the following relation when the illumination branched structure 20 is provided: γ=θ/M; where M is the magnification of the projection lens of the illumination lens group 23, and θ is the angle between the incident light of the illumination branch structure 20 and the reference incident plane with respect to the incident plane of the sample 10. In a certain light difference range, the rotation angle gamma of the rectangular long side of the light emitting end surface of the light homogenizing cavity 22 in the illumination branch structure 20 relative to the direction perpendicular to the optical axis of the illumination lens group 23, that is, the long side space inclination angle of the light emitting surface of the light homogenizing cavity 22 is slowly adjusted, so that the second azimuth angle of the light homogenizing cavity 22 can be adjusted to be approximate to or just meet the above relation, and then the imaging light spot on the surface of the sample 10 corresponds to the slow rotation angle theta relative to the reference imaging light spot. By matching with the adjustment of the first azimuth angle, the light outlet light spots of the emergent light end surface of the light homogenizing cavity 22 are effectively conjugate projected on the surface of the sample 10, and simultaneously, the imaging light spots generated by the irradiation of the four illumination branch structures 20 on the surface of the sample 10 are gradually and slowly overlapped, so that the energy utilization rate is improved, and the illumination uniformity of the annular illumination branch structures 20 is improved.

Optionally, the manner of adjusting the first azimuth angle and the second azimuth angle may be specifically as follows: firstly, a Mark plate, which can be a ceramic diffuse reflection plate, is placed on a workpiece table, all branch input light sources 21 are sequentially turned on, then focused light spots are sequentially imaged by a camera of a detection module, and an A1 light spot imaging image, an A2 light spot imaging image, an A3 light spot imaging image and an A4 light spot imaging image of four illumination branch structures Z1, Z2, Z3 and Z4 are respectively recorded. If the gray level difference of the images A1-A4 is large, the beta angle of the light homogenizing cavity 22 with large difference is adjusted to ensure that the end face of the light homogenizing cavity 22 is conjugated with the surface of the wafer, so that the light intensity of the branch is consistent with the average value; if the rotation of the light spots of the images A1 to A4 are not coincident, the gamma angle is adjusted by the dodging cavity adjusting mechanism 25 to enable the light spots A1 to A4 to be rotationally coincident, or the XY axes of the illumination branch structure 20 can be integrally matched and adjusted to enable the light spots A1 to A4 to be coincident; and (5) starting to detect the detected sample 10, finally obtaining a signal scattered by a dark field of the detected sample 10, and finishing detection by processing a later-stage image algorithm.

By adjusting the second azimuth angle, the emergent light spots of each branch illumination light path can be perfectly overlapped at the center of the sample 10, so that the illumination uniformity is improved, and the mechanism device with complex design is avoided to assist the eccentric adjustment.

In addition, the embodiment of the application also provides a detection method, which is applied to the detection device in any embodiment; the method comprises the following steps: step 100 and step 110.

Step 100: illuminating the sample 10 to be detected by adopting an illuminating device;

step 110: signal light generated after irradiation of the sample 10 is detected to detect the sample 10.

For example, since the principle of the detection method according to the embodiment of the present application for solving the problem is similar to that of the foregoing embodiment of the detection device, the implementation of the detection method according to the embodiment of the present application may refer to the description of the foregoing embodiment of the detection device, and the repetition is omitted.

In addition, the embodiment of the application also provides an adjusting method which is applied to adjusting the detection device in any embodiment; the method comprises the following steps: step 120 and step 130.

Step 120: adjusting a first azimuth angle of the illumination branch structure 20 in the illumination branch structure 20 so that an emergent light end surface of the dodging cavity 22 is conjugated with the surface of the sample 10;

step 130: the second azimuth angle of the light homogenizing chamber 22 in the illumination branch structure 20 is adjusted so that the output light spot of each illumination branch structure 20 received by the surface of the sample 10 coincides.

For example, since the principle of the adjusting method in the embodiment of the present application for solving the problem is similar to the foregoing embodiment of the detecting device in which the first azimuth angle and the second azimuth angle of the illumination branch structure 20 are configured, the implementation of the adjusting method in the embodiment of the present application may refer to the description of the foregoing embodiment of the detecting device in which the first azimuth angle and the second azimuth angle of the illumination branch structure 20 are configured, and the repetition is omitted.

In addition, the embodiment of the application also provides a method for designing the light source 21, which is applied to the lighting device in any of the above embodiments, and the light source 21, the light homogenizing cavity 22 and the lighting lens group 23 in the lighting branch structure 20 are sequentially arranged along the light path; the method comprises the following steps: step 150.

Step 150: the azimuth angle of the illumination branch structure 20 is acquired so that the outgoing light end face is conjugated and imaged to the surface of the sample 10 through the lens of the illumination lens group 23.

Illustratively, the azimuth angle of the obtained illumination branching structure 20 may be an azimuth angle that enables the outgoing light end surface of the dodging cavity 22 to be conjugated and imaged to the surface of the sample 10 through the lens of the illumination lens group 23, specifically may be: the position of the light homogenizing chamber 22 and the azimuth angle related to the light exit surface, for example: the first azimuth angle and the second azimuth angle of the illumination branch structure 20 further carry out targeted dodging on the illumination light provided by the light source 21, the light beam is incident to the entrance of the dodging cavity 22, and the light outlet surface of the dodging cavity 22 is conjugated with the surface of the sample 10 through the illumination lens group 23. The light source 21 emits light, and after entering the light homogenizing cavity 22, the light is uniformly diffused to the emergent light end face of the illumination lens group 23 through the actions of multiple reflection, refraction, scattering and the like in the light homogenizing cavity 22, so that uniform illumination of a wafer is realized, meanwhile, the illumination power density can be improved, and stray light is well inhibited.

By adjusting the azimuth angle of the illumination branch structure 20, the design effect of the light source 21 for illuminating light is further achieved, and the flexibility of design is improved.

In one embodiment, step 150 may include: step 151.

Step 151: acquiring a first azimuth angle of the illumination branch structure 20 so as to enable the emergent light end surface of the light homogenizing cavity 22 to be conjugate with the surface of the sample 10, wherein the first azimuth angle is an included angle of the emergent light end surface of the light homogenizing cavity 22 relative to the surface of the sample 10; wherein the first azimuth angle satisfies a relation: beta = δ×Μ; where β is a first azimuth angle, δ is an angle between the light emitting direction of the light emitting end face of the light homogenizing cavity 22 and the normal line of the surface of the sample 10, and M is the magnification of the projection lens of the illumination lens group 23.

Illustratively, since the principle of the design method in the embodiment of the present application for solving the problem is similar to the foregoing embodiment of the detection device in which the first azimuth angle of the illumination branch structure 20 is configured, the implementation of the design method in the embodiment of the present application may refer to the description of the foregoing embodiment of the detection device in which the first azimuth angle of the illumination branch structure 20 is configured, and the repetition is omitted.

In one embodiment, the light emergent end surface of the light homogenizing cavity 22 is rectangular, the plurality of illumination branch structures 20 comprise reference illumination branch structures 20, the incident light of the reference illumination branch structures 20 has a reference incident surface relative to the sample 10, and the image of the light emergent end surface of the light homogenizing cavity 22 of the reference illumination branch structures 20 has a reference extending direction; the design method also comprises the following steps: acquiring an image of the light spot extending direction on the light emitting end face of the light homogenizing cavity 22 of the reference lighting branch structure 20 to obtain a reference extending direction of the light emitting end face of the light homogenizing cavity 22; step 150 may further include: step 152.

Step 152: acquiring a second azimuth angle of the illumination branch structure 20, wherein the second azimuth angle is an included angle between the extending direction of the emergent light end face of the light homogenizing cavity 22 and the reference extending direction; acquiring a second azimuth angle of the illuminating branched structure 20 includes: acquiring an included angle between an incident light of the illumination branch structure 20 relative to an incident surface of the sample 10 and a reference incident surface; the second azimuth angle is obtained according to the formula γ=θ/M, where γ is the second azimuth angle, M is the magnification of the projection lens of the illumination lens group 23, and θ is the angle between the incident light illuminating the branching structure 20 with respect to the incident plane of the sample 10 and the reference incident plane.

For example, since the principle of the design method in the embodiment of the present application for solving the problem is similar to the aforementioned embodiment of the detection device in which the second azimuth angle of the light homogenizing chamber 22 is configured, the implementation of the design method in the embodiment of the present application may refer to the description of the embodiment of the detection device in which the second azimuth angle of the light homogenizing chamber 22 is configured, and the repetition is omitted.

In one embodiment, step 152 may further comprise: step 153.

Step 153: the direction of the second azimuth angle of the illumination branch structure 20 is acquired according to the principles of the poloxamer imaging.

Illustratively, the principles of the imaging of the poloxamer achieve different focusing effects by changing the propagation direction of the light, based on the snell's law, i.e. there is a fixed relationship between the angle of incidence and the angle of refraction as the light propagates between two different media, and the light can be focused in a specific direction due to the deviating effect of refraction as it passes through a convex lens. At the same time of acquiring the second azimuth angle, the light spot extending direction of the second azimuth angle of each light homogenizing cavity 22 in the multiple illumination branch structures 20 can be acquired respectively according to the principle, and the light spot extending direction is adjusted, so that the light spots can be distributed at any position on the surface of the sample 10, and the design capability of the light source 21 is improved.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The above-described apparatus embodiments are merely illustrative, and the division of the modules is merely a logical function division, and there may be additional divisions when actually implemented, and for example, multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some communication interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form. The functional modules in the embodiments of the present application may be integrated together to form a single part, or each module may exist alone, or two or more modules may be integrated to form a single part.

In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

The foregoing is merely exemplary embodiments of the present application and is not intended to limit the scope of the present application, and various modifications and variations may be suggested to one skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A lighting device, the device comprising: an illumination branching structure; the lighting branch structure comprises: a light source, a light homogenizing cavity and an illumination lens group;

the dodging cavity comprises: an incident light end face, a cavity and an emergent light end face; the incident light end face and the emergent light end face are arranged at two ends of the cavity; the light source is arranged on one side of the incident light end face; the illumination lens group is arranged on one side of the emergent light end face, and the illumination lens group enables the emergent light end face to be conjugate with the surface of the sample;

The light source in the illumination branch structure is used for providing incident light, the light homogenizing cavity is used for receiving the incident light and irradiating the incident light to the illumination lens group, and the illumination lens group is used for obliquely irradiating the sample based on the incident light; the azimuth angle of the illumination branch structure is configured to enable the emergent light end face to be conjugated and imaged to the surface of the sample through the lens of the illumination lens group.

2. A lighting device as recited in claim 1, wherein an azimuth angle of said lighting branch structure comprises: a first azimuth angle;

the first azimuth angle is an included angle of an emergent light end face of the light homogenizing cavity relative to the surface of the sample; the first azimuth angle satisfies the relation: beta = δ×Μ;

wherein, beta is the first azimuth angle, delta is the included angle between the light emitting direction of the light emitting end face of the light homogenizing cavity and the normal line of the sample surface, and M is the magnification of the projection lens of the illumination lens group.

3. A lighting device as recited in claim 1, wherein said device comprises: a plurality of illumination branch structures; the light source comprises a plurality of light distribution cavities, a plurality of light distribution cavities and a plurality of light distribution cavities, wherein the light distribution cavities are arranged in the light distribution cavities; the azimuth angle of the illumination branch structure further comprises: a second azimuth angle;

The second azimuth angle is an included angle between the extending direction of the emergent light end face of the light homogenizing cavity and the reference extending direction; the second azimuth angle satisfies the relation: γ=θ/M;

wherein, gamma is the second azimuth angle, M is the magnification of the projection lens of the illumination lens group, and θ is the included angle between the incident light of the illumination branch structure relative to the incident surface of the sample and the reference incident surface.

4. A lighting device as recited in claim 3, wherein said reference plane of incidence is coincident with or perpendicular to the direction of elongation of the spot.

5. A lighting device as recited in any one of claims 1-4, wherein said lighting branch structures are uniformly distributed around said sample centered on said sample.

6. A lighting device as recited in claim 5, wherein an azimuth angle of said lighting branch structure further comprises: a third azimuth angle;

the third azimuth angle is an included angle of projection of the optical axis of each adjacent two of the plurality of illumination branch structures on the surface of the sample; the third azimuth angle satisfies the relation: α=2pi/n; wherein n is the number of the plurality of illumination branch structures.

7. A lighting device as recited in any one of claims 1-4, wherein said lighting branch structure further comprises: and the turning mirror is positioned between the light homogenizing cavity and the sample and is used for changing the direction of light rays emitted from the emergent light end face of the light homogenizing cavity.

8. A lighting device as recited in claim 7, wherein said turning mirror is disposed between an outgoing light end surface of said light homogenizing chamber and said illumination lens group; or between the illumination lens group and the sample.

9. A lighting device as recited in claim 7, wherein said illumination lens group comprises: a first lens and a second lens; the first lens is arranged on one side close to the emergent light end face of the light homogenizing cavity, and the second lens is arranged on one side close to the sample;

the deflection mirror is arranged between the first lens and the second lens and is used for deflecting the emergent light rays passing through the first lens from the light homogenizing cavity from the vertical direction vertical to the sample surface to the oblique direction relative to the sample surface, so that the emergent light rays pass through the second lens and then obliquely irradiate the sample surface.

10. A lighting device as recited in any one of claims 1-4, wherein said lighting branch structure further comprises: and the dodging cavity adjusting mechanism is used for adjusting the light spot size and direction of the light at the incident light end surface of the dodging cavity and/or the light spot size and direction of the light at the emergent light end surface of the dodging cavity.

11. A lighting device as recited in claim 10, wherein said dodging cavity adjustment mechanism is disposed outside an incident light end face and/or outside an exit light end face of said dodging cavity.

12. A lighting device as recited in claim 10, wherein said light homogenizing chamber is a reflective chamber structure defined by a plurality of reflective mirrors, and said light homogenizing chamber adjusting mechanism is configured to adjust a size of an enclosed area defined by said reflective mirrors, so as to adjust a spot size and a direction of light at an incident light end surface of said light homogenizing chamber and/or an exit light end surface of said light homogenizing chamber.

13. A lighting device as recited in claim 1, wherein said device comprises: the light spots formed by the plurality of the lighting branch structures coincide, and the plurality of the lighting branch structures are symmetrically arranged around the center of the light spot; the light source couples the emitted light to the incident light end face of the light homogenizing cavity in the plurality of illumination branch structures through a plurality of optical fiber output ends.

14. A detection device, the device comprising: a detector and the illumination device of any one of claims 1-13;

the illumination device is used for obliquely irradiating the sample, and the incident light of the obliquely irradiation has a non-zero included angle with the normal line of the sample;

The detector is used for detecting signal light generated by the sample after oblique irradiation so as to detect the sample according to the signal light.

15. The detection apparatus according to claim 14, characterized in that the apparatus further comprises: an objective table; the object stage is used for placing a sample to be detected, the detector is arranged opposite to the object stage, and the optical axis of the detector is perpendicular to the surface to be detected of the sample;

the lighting device is used for: obliquely irradiating the sample placed on the object stage;

the detector is also for: and collecting scattered light of the sample placed on the object stage after being obliquely irradiated by the illumination device, and carrying out imaging detection on the surface of the sample based on the scattered light.

16. The apparatus of claim 14, wherein the first azimuthal angle of the illumination branching structure is configured to conjugate the light exit end surface of the light distribution chamber with the sample surface.

17. The detection apparatus according to claim 14, wherein the second azimuth angle of the dodging cavity is configured such that the output spot of each illumination branch structure received by the sample surface coincides.

18. A method of detection, characterized in that the method is applied to the detection device of any one of claims 14-17; the method comprises the following steps:

Illuminating a sample to be detected by adopting an illumination device;

detecting signal light generated after the sample is irradiated so as to detect the sample.

19. A method of adjustment, characterized in that it is applied to the adjustment of the detection device according to any one of claims 14-17; the method comprises the following steps:

adjusting a first azimuth angle of an illumination branch structure in the illumination branch structure so as to enable an emergent light end face of the light homogenizing cavity to be conjugate with the surface of the sample;

and adjusting a second azimuth angle of the light homogenizing cavity in the illumination branch structure so as to enable output light spots of each illumination branch structure received by the sample surface to coincide.

20. A light source design method, which is characterized in that the method is applied to the lighting device of any one of claims 1-13, and is characterized in that a light source, a light homogenizing cavity and a lighting lens group in the lighting branch structure are sequentially arranged along a light path; the method comprises the following steps:

and acquiring the azimuth angle of the illumination branch structure so that the emergent light end face is subjected to conjugate imaging to the sample surface through the lens of the illumination lens group.

21. The method of claim 20, wherein obtaining the azimuth angle of the illumination branch structure comprises:

Acquiring a first azimuth angle of the illumination branch structure so as to enable the emergent light end face of the light homogenizing cavity to be conjugate with the sample surface, wherein the first azimuth angle is an included angle of the emergent light end face of the light homogenizing cavity relative to the sample surface; wherein the first azimuth angle satisfies a relation: beta = δ×Μ; wherein, beta is the first azimuth angle, delta is the included angle between the light emitting direction of the light emitting end face of the light homogenizing cavity and the normal line of the sample surface, and M is the magnification of the projection lens of the illumination lens group.

22. The method of claim 20, wherein the light-exit end face of the light-homogenizing chamber is rectangular, the plurality of illumination branch structures include reference illumination branch structures, the incident light of the reference illumination branch structures has a reference incident plane with respect to the sample, and the image of the light-spot extending direction on the light-exit end face of the light-homogenizing chamber of the reference illumination branch structures has a reference extending direction;

the design method further comprises the following steps: acquiring an image of the light spot extending direction on the light emitting end face of the light homogenizing cavity of the reference lighting branch structure to obtain a reference extending direction of the light emitting end face of the light homogenizing cavity;

acquiring an azimuth angle of the illumination branch structure, wherein the azimuth angle comprises acquiring a second azimuth angle of the illumination branch structure, and the second azimuth angle is an included angle between an extending direction of an emergent light end surface of the light homogenizing cavity and the reference extending direction; acquiring a second azimuth angle of the illumination branch structure, comprising: acquiring an included angle between an incident surface of the illumination branch structure relative to a sample and the reference incident surface; and obtaining a second azimuth angle according to a formula gamma=theta/M, wherein gamma is the second azimuth angle, M is the magnification of the projection lens of the illumination lens group, and theta is the included angle between the incident light of the illumination branch structure relative to the incident surface of the sample and the reference incident surface.

23. The method of claim 20, wherein obtaining the second azimuth angle of the illumination branch structure further comprises: and acquiring the direction of the second azimuth angle of the illumination branch structure according to the principle of the Mr imaging.