An optical path device, an optical detection method, and a detection apparatus

Abstract

An optical path device, an optical detection method and a detection device, the optical path device comprising a side incidence optical path assembly and a lens assembly, the side incidence optical path assembly comprising a detection light source and an expander mirror set, the detection light source providing an incident light beam, the expander mirror set being configured to spread and shape the incident light beam in a first direction to form parallel first direction detection light beams and to spread and shape the incident light beam in a second direction to form non-parallel second direction detection light beams; the first direction detection light beams exiting the lens assembly to form a light spot on a surface to be detected of an object to be detected; the second direction detection light beams non-parallelly entering a surface of the lens assembly and having a beam size, the second direction detection light beams exiting the lens assembly to the surface to be detected and forming the light spot. The present application provides a detection optical path avoiding a central aperture of the lens assembly, which can effectively reduce the risk of lens damage and achieve more reliable and efficient wafer defect detection.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optical inspection technology, specifically to an optical path device, an optical inspection method, and an inspection equipment. Background Technology

[0002] Wafer defect inspection refers to the process of detecting and locating physical and chemical defects such as particles and scratches on the surface of a wafer. This step directly affects chip quality and yield, and is one of the key steps in semiconductor manufacturing. Wafer defect inspection involves specifically illuminating the area to be inspected on the wafer and collecting scattered light to determine the presence of defects, and then using a high-precision moving platform to perform a full-area scan of the wafer. This method has the advantages of high detection accuracy and high speed, and is widely used in the industry.

[0003] Currently, wafer defect inspection mostly employs point illumination and point detection methods, typically using a reflector or a large numerical aperture (NA) objective to maximize the collection of scattered light, combined with a high-precision motion platform to achieve point scanning inspection. This approach can only inspect a tiny area at a time.

[0004] However, large numerical aperture objectives have a short working distance, typically only a few millimeters. In normal incident illumination testing, high-power deep ultraviolet lasers need to pass through the inside of the objective, posing a risk of lens damage. To mitigate this problem, traditional methods often involve creating an opening in the center of the lens. However, this is difficult to manufacture, mechanically opening the lens can introduce stress, leading to a decrease in lens surface accuracy, and the aperture walls are prone to generating stray light, ultimately affecting the optical performance of the objective.

[0005] To solve the above technical problems, the traditional approach is to create an opening in the center of the front lens group. However, the opening process is difficult, and the stress caused by mechanical opening will degrade the lens surface accuracy. Stray light will also be introduced into the hole wall, which will seriously affect the optical performance of the objective lens. Summary of the Invention

[0006] This invention provides an optical path device, an optical detection method, and a detection equipment to solve the problems of mechanical damage and image quality degradation caused by mechanical opening of lenses, and to avoid lens damage. It also solves the problem that the spot size of the wafer detection spot cannot be adjusted in the first direction (tangential direction of the wafer) and / or the second direction (radial direction of the wafer), which affects the detection sensitivity and detection yield.

[0007] According to a first aspect, this embodiment provides an optical path device, comprising:

[0008] A side-incident optical path assembly includes a detection light source and a beam expander group. The detection light source is used to provide an incident beam, and the beam expander group is used to expand and shape the incident beam in a first direction to form a parallel first-direction detection beam and to expand and shape the incident beam in a second direction to form a non-parallel second-direction detection beam.

[0009] Lens assembly;

[0010] The first direction detection beam is emitted through the lens assembly onto the test surface of the object to be tested and forms a light spot on the test surface. The light spot has a first size related to the first direction. The second direction detection beam is incident on the surface of the lens assembly at a non-parallel incident beam angle and has a beam size. The second direction detection beam is emitted from the lens assembly onto the test surface and forms a light spot on the test surface. The light spot has a second size related to the second direction, which is perpendicular to the first direction.

[0011] The beam expander group includes cylindrical lenses, the curvature of which lies within the shaping section in the second direction;

[0012] The relationship between the second dimension and the incident beam angle is as follows:

[0013] ,in, The second dimension is f, where f is the focal length of the lens assembly and θ is the angle of the incident beam.

[0014] In one embodiment, the beam expander group is a beam expander cylindrical lens group, including a beam expander cylindrical lens for adjusting the incident beam angle of the first direction detection beam, and the beam expander cylindrical lens group further includes a beam expander cylindrical lens for adjusting the incident beam angle of the second direction detection beam.

[0015] In one embodiment, the beam expander assembly includes a second cylindrical lens and a third cylindrical lens, forming a Keplerian beam expander. The distance between the second cylindrical lens and the third cylindrical lens is adjustable to change the incident beam angle of the detection beam in the second direction. The lens curvature of the second cylindrical lens and the third cylindrical lens is located within the shaping section in the second direction, and the second dimension changes with the adjustment of the incident beam angle.

[0016] Optionally, the side-incident optical path assembly also includes a fourth cylindrical lens for compound focusing with the lens assembly, the curvature of the fourth cylindrical lens being located within the shaping section in the second direction.

[0017] Optionally, the lateral incident optical path assembly also includes a fifth cylindrical lens for compensating for astigmatism, the curvature of which is located within the shaping section in the first direction and is orthogonal to the curvatures of the second, third, and fourth cylindrical lenses.

[0018] In the standalone normal incidence embodiment, the side incidence optical path assembly further includes a beam splitter prism, and the detection light source passes through a second cylindrical lens, a third cylindrical lens, a fourth cylindrical lens, a fifth cylindrical lens, a beam splitter prism, and a lens assembly used as the normal incidence assembly, and forms a normal incidence light spot on the surface to be measured.

[0019] When combined with the oblique incident light path, the side incident light path assembly also includes a beam splitter and an optical shaping element. The detection light source passes through the beam splitter and optical shaping element used as the oblique incident assembly and forms an oblique incident light spot on the surface to be tested.

[0020] According to the second aspect, this embodiment provides an optical detection method, including a detection light source and a beam expander assembly:

[0021] The light source emits an incident beam;

[0022] The beam expander array expands and shapes the incident beam in the first direction to form a parallel detection beam in the first direction.

[0023] The beam expander assembly expands and shapes the incident beam in the second direction to form a non-parallel second-direction detection beam. The second-direction detection beam is adjusted by the incident beam angle of the lens assembly. When the incident beam angle increases or decreases, the beam size of the second-direction detection beam incident on the surface of the lens assembly increases or decreases synchronously.

[0024] On the surface of the object to be tested, a detection beam in the first direction is focused by a lens assembly and a light spot is formed on the surface of the object to be tested. The light spot has a first size related to the first direction.

[0025] On the surface of the object to be tested, a detection beam in a second direction is focused by a lens assembly and a light spot is formed on the surface of the object to be tested. The light spot has a second size related to the second direction. The second size changes positively with the adjustment of the incident beam angle. The second direction is perpendicular to the first direction.

[0026] The beam expander assembly includes cylindrical lenses, the curvature of which lies within the shaping section of the second direction;

[0027] The relationship between the second dimension and the incident beam angle is as follows:

[0028] ,in, The second dimension is the second dimension formed when the detection beam is incident on the surface to be measured in the second direction, f is the focal length of the lens assembly, and θ is the incident beam angle.

[0029] Optionally, the normal incidence component is configured to form a normal incidence spot on the test surface of the object under test; and / or

[0030] The oblique incidence component is set to form an oblique incidence spot on the surface of the object to be tested;

[0031] The normal incident light spot and the oblique incident light spot have the same spot size and position in the first and second directions, respectively.

[0032] Optionally, the normal incident light spot and the oblique incident light spot have the same spot size in the first direction and the second direction, but different positions;

[0033] The normally incident light spot and the obliquely incident light spot are staggered by a set distance along the rotational tangent of the object under test. In the rotational direction of the object under test, the normally incident light spot or the obliquely incident light spot that first illuminates the surface under test is the secondary light spot, and the normally incident light spot or the obliquely incident light spot that illuminates after passing through the set distance is the primary light spot, so as to avoid explosion.

[0034] According to a third aspect, this embodiment provides a detection device, including: the optical path device of the first aspect described above, the optical path device including a side-incident optical path assembly and a lens assembly.

[0035] The side-incident optical path assembly is used to provide an incident beam. The incident beam is expanded and shaped in a first direction to form a parallel first-direction detection beam, and simultaneously expanded and shaped in a second direction to form a non-parallel second-direction detection beam. The second direction is perpendicular to the first direction. The first-direction detection beam is emitted through a lens assembly onto the surface of the rotating test object, forming a detection spot of a defined size in the first rotation direction. The second-direction detection beam is emitted through the lens assembly onto the surface of the test object, making the second-direction size of the detection spot adjustable. The detection spot passes through the surface of the test object to form a signal light.

[0036] A detector is used to receive signal light and form detection information based on the signal light.

[0037] The optical path device, optical detection method, and detection equipment according to the above embodiments have the following technical effects:

[0038] A non-destructive positive incident illumination design for the objective lens system has been achieved. Through optimization of the optical path structure and adjustment mechanism, there is no need to make openings or special material treatments inside the lens assembly of the objective lens system, avoiding the mechanical damage and image quality degradation problems of optical elements caused by traditional methods. This significantly improves the reliability and lifespan of the system and enhances the overall effect of defect detection.

[0039] A cylindrical mirror control system with independent tangential and radial directions can be established, that is, a cylindrical mirror control system with independent first and second directions. By designing separate tangential and radial beam expander cylindrical mirror groups, independent control of the basic beam shape is achieved. In one embodiment, the stability of the tangential beam size and the adjustability of the radial beam size can also be achieved.

[0040] Furthermore, a defocus control mechanism with flexible adjustable second-direction spot size was implemented. With the first-direction cylindrical lens group fixed, the spot size on the wafer surface under test is defocused by adjusting the second-direction cylindrical lens group, thereby dynamically adjusting the second-direction spot size. A shorter second-direction spot size is used in high-sensitivity mode, and a longer second-direction spot size is used in high-yield mode to meet the detection requirements under different yield conditions. This significantly improves equipment applicability and production efficiency while ensuring sensitivity.

[0041] The beam expander assembly of this invention expands the beam in a second direction before it enters the front lens of the objective lens, increasing the size of the beam illuminating the lens assembly (D2 increases to D3). This avoids damage to optical components under high-power illumination and allows the size of the second-direction spot (radial spot) converging on the wafer surface to be dynamically adjusted (d3≥d2), thus ensuring higher production efficiency (i.e., high detection efficiency). At the same time, the beam remains parallel to the first direction of incidence before entering the front lens of the objective lens, and the size (d1) of the first-direction spot (tangential spot) remains unchanged, ensuring the stability of high sensitivity.

[0042] Furthermore, the overall optical path scheme for oblique incidence enables polarization control, autofocus, and spot overlap correction, improving the applicability and production efficiency of the detection system. It also allows for master / slave spot layout without wedges, avoiding the destruction of large-size defects on the wafer. Attached Figure Description

[0043] Figure 1 This is a schematic diagram showing the formation of light spots in the X and Y directions under existing normal incident illumination.

[0044] Figure 2 This is a schematic diagram of the optical detection of a detection device according to one embodiment;

[0045] Figure 3 This is a schematic diagram of adjustable spot sizes in the X and Y directions of normal incident illumination in one embodiment;

[0046] Figure 4 This is a side view schematic diagram of the second-direction shaping optical path in one embodiment;

[0047] Figure 5 This is a top view schematic diagram of the first direction shaping optical path in one embodiment;

[0048] Figure 6 This is a schematic diagram illustrating the relationship between the optical path for adjusting the spacing of the beam-expanding column lens group and the beam spot size in one embodiment;

[0049] Figure 7 This is a schematic diagram of the overall optical path structure for oblique incidence in one embodiment;

[0050] Figure 8This is a schematic diagram of the optical detection of a detection device according to another embodiment;

[0051] Figure 9 This is a schematic diagram of the overall optical path structure for oblique incidence in another embodiment;

[0052] Figure 10 This is a schematic diagram of the overall optical path structure for oblique incidence in another embodiment;

[0053] Figure 11 This is a schematic diagram of a master-slave spot anti-explosion wafer detection method in one embodiment;

[0054] Figure 12 This is a flowchart of an optical detection method in one embodiment. Detailed Implementation

[0055] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0056] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0057] The serial numbers assigned to components in this document, such as "first" and "second," are used solely to distinguish the described objects and have no sequential or technical meaning. "Multiple" means two or more. Unless otherwise specified, "connection" or "linkage" in this application includes both direct and indirect connections (linkages).

[0058] Please refer to Figure 1 The image shows an existing normal incident illumination method for wafer inspection. Figure 1 In the existing normal incident illumination method shown, a wafer is formed on the wafer surface 100. Figure 1The light spot 105' shown in the X and Y directions ( Figure 1 The light spot shown in (a3) ​​is an enlarged image for clearer display. This represents the size of the light spot in the 105'X direction. This refers to the size of the light spot in the 105'Y direction. The width of the incident beam in the X direction of the front lens 103'. Let X be the width of the incident beam in the Y direction of the front lens 103'. The Y-axis corresponds to the radial direction of the illumination spot on the wafer, and the X-axis corresponds to the tangential direction of the wafer.

[0059] The inventors discovered that both the X and Y directions are achieved by using parallel light incident on the front lens 103' and converging it onto the wafer surface. Without considering the aberrations of the front lens 103', the incident beam width of the front lens 103' is... With the converged beam width satisfy: Where λ is the incident laser wavelength, and n can be 1, 2, 3, ..., n. A narrow converging beam (typically on the order of several micrometers) in the X direction of spot 105' corresponds to a wide incident beam, while a wide converging beam (typically on the order of hundreds of micrometers) in the Y direction of spot 105' corresponds to a narrow incident beam. The spot illuminating the front lens group 103' is as follows: Figure 1 As shown; it can be seen from the formula that the incident beam width of the front lens 103' is... With the converged beam width (i.e., spot size) are inversely proportional. To improve detection yield, the size of the illumination spot in the Y direction (i.e., the width of the converged beam) is... It needs to be magnified several times to tens of times, in the incident beam width of the front lens 103' If the beam size shrinks, it can easily lead to excessively high energy density in the 103' region of the front lens, causing lens damage. The size of the illumination spot in the X direction needs to maintain a narrow, convergent beam (typically a few micrometers) to obtain an extremely high-precision spot with a small X-axis size to identify smaller defects and improve detection sensitivity. Therefore, ensuring high detection yield while avoiding damage to the front lens under high sensitivity presents a challenge. Please refer to... Figure 2 The figure shows a detection device according to an embodiment of the present invention (only vertical incidence is shown). The detection device includes an objective lens 102, an optical path device for forming a detection spot, and a detector 107.

[0060] Detector 107 is used to receive the signal light collected by the objective lens and to form detection information by imaging within detector 107. Detector 107 may include, but is not limited to, CCD detector, TDI detector, photomultiplier tube (PMT), avalanche photodiode (APD), etc.

[0061] The objective lens 102 of the detection device includes a front lens group for receiving signal light, which is a lens assembly 103. The optical path device is a side-incident optical path assembly 200. Figure 2 In the illustrated embodiment, the lateral incident optical path assembly 200 provides the incident beam through an opening in the outer wall of the objective lens 102. Alternatively, in... Figure 8 In the illustrated embodiment, the lateral incident optical path assembly 200 enters through the prism 104 above the objective lens 102, thus eliminating the need for drilling holes in the outer wall of the objective lens 102. This optical path device utilizes a portion of the lens group within the objective lens 102 itself, achieving a vertical illumination spot design through an external lens group added to the optical path device, without requiring an opening in the center of the objective lens. The lateral incident optical path assembly 200 enters through an opening in the side wall of the objective lens 102, forming a vertical illumination spot by arranging the optical path above the objective lens 102.

[0062] exist Figure 2 as well as Figure 8 In the illustrated embodiment, the lateral incident optical path assembly 200 includes a detection light source and a beam expander assembly 201. Figure 4 , Figure 7 , Figure 9 as well as Figure 10 In the embodiment shown, the lateral incident optical path assembly 200 is a beam expander lens group.

[0063] exist Figure 2 In this embodiment, the beam expander lens group expands and shapes the detection light source in the first direction (X-axis) to form a parallel first-direction detection beam, and simultaneously expands and shapes it in the second direction (Y-axis) to form a non-parallel second-direction detection beam.

[0064] Furthermore, the first direction detection beam exits through the lens assembly 103 and is projected onto the test surface W of the object under test, forming a light spot on the test surface. The light spot has a first size related to the first direction. The lens curvature of the beam expander determines the beam size of the second direction detection beam incident on the surface of the lens assembly. The second direction detection beam exits from the lens assembly and is projected onto the test surface, forming a light spot on the test surface. The light spot has a second size related to the second direction, which is perpendicular to the first direction.

[0065] Figure 3 This invention demonstrates the core concept of a detection technology that achieves both high detection yield and high sensitivity while avoiding lens damage. The incident beam of the detection light source is circular or elliptical. The incident beam is shaped into parallel light by the cylindrical lens group 201 in the first direction (X-axis) and then converged by the lens assembly 103 onto the surface of the wafer W, forming a light spot on the surface to be measured, such as... Figure 3 The light spot on the surface to be tested shown in (b3) has a first size related to a first direction. The incident beam is shaped into non-parallel light in the second direction (Y-axis) by the beam expander assembly 201 and then converged onto the surface of the wafer W by the lens assembly 103. A spot with a second dimension related to the second direction is further formed on the surface under test. The second direction is perpendicular to the first direction.

[0066] The angle between the edge ray of the non-parallel light in the second direction (Y-axis) and the horizontal line is θ, also known as the incident beam angle (θ), which is the angle between the edge ray of the second-direction detection beam and the optical axis of the lens assembly 103. After the incident beam is expanded by the beam expander group 201, the second-direction detection beam is incident on the second dimension of the wafer surface under test. The relationship with the incident beam angle (θ) is as follows:

[0067] ,in, The second dimension is the second dimension formed when the detection beam is incident on the surface to be measured in the second direction, f is the focal length of the lens assembly of the objective lens, and θ is the angle of the incident beam.

[0068] It can be seen that the size of the beam incident on the surface of the lens assembly 103 can be changed by changing the incident beam angle θ (for example, by changing the incident beam angle by translating the lens). (Right now Increased to This significantly reduces the risk of damage to the lens assembly 103. Simultaneously, changing the incident beam angle θ also alters the second size of the light spot in the second direction. Increase the second dimension in the second direction. It can cover a large area at once, further improving the detection yield, and solves the problem of the incident beam width of the front lens. With the converged beam width The inverse relationship between light output and lens damage cannot be simultaneously addressed. To address different output requirements, the second size of the light spot is adjusted. The length is used to achieve this. Meanwhile, to ensure detection sensitivity, the first direction (X-axis) shaping remains parallel light incidence, and the beam size incident on the surface of the lens assembly 103 is... (i.e., still) ), focusing the illumination in the first direction (X-axis) to (On the micrometer scale) to increase the energy density of a single laser point, thereby enhancing the intensity of the scattered signal from the defect and improving detection sensitivity to identify even smaller defects. and Inversely proportional relationship, It can guarantee in a very small size This is to avoid damage to the lens assembly 103.

[0069] exist Figure 2 In the illustrated embodiment, the front lens group of the objective lens 102, i.e., the lens assembly 103, is utilized. A shorter second-direction spot size is achieved on the wafer in high-sensitivity mode, and a longer detection spot size in the second direction is obtained in high-yield mode by adjusting the divergence angle of the illumination beam. By flexibly adjusting the divergence angle of the illumination beam, the size of the spot in the second direction (Y-axis) can be effectively changed, allowing the long spot to cover a large area at once. Simultaneously, due to the size of the beam illuminating the surface of the lens assembly 103... The larger size results in a significantly lower energy density, thereby greatly reducing the risk of lens damage.

[0070] Combination Figure 1 , Figure 3 It can be seen that by using the beam expander assembly of the present invention to expand the beam in a second direction before it enters the objective lens group (i.e., the lens assembly 103), the size of the beam illuminating the lens assembly is increased. Increased to This avoids damage to optical components under high-power illumination and allows for dynamic adjustment of the size of the light spot converged on the wafer surface. ≥ This ensures higher production efficiency (i.e., high detection efficiency), while also reducing the spot size in the X-axis direction. Nothing has changed; it maintains high sensitivity and stability.

[0071] In addition, Figure 3 , Figure 7 , Figure 9 as well as Figure 10 In this embodiment, when using a beam expander lens group, the beam size is changed on the lens assembly 103 by adjusting the optical path of the beam expander lens group. While changing the incident beam angle θ, the size of the beam converging on the wafer in the second direction (Y-axis) is also adjusted (i.e., the spot size).

[0072] The lens curvature of the beam expander 201 lies within the shaping section in the second direction. The lens curvature of the beam expander 201 determines the beam size of the detection beam in the second direction incident on the surface of the lens assembly 103. .

[0073] Understandably, in terms of spot size adjustment, through reasonable optical path design, it is possible to simultaneously adjust the first size of the spot in the first direction and the second size in the second direction. For example, the beam-expanding cylindrical lens group includes a Galilean-type beam expander or a Keplerian-type beam expander for adjusting the divergence angle of the detection beam in the first direction, and / or the beam-expanding cylindrical lens group also includes a Galilean-type beam expander or a Keplerian-type beam expander for adjusting the divergence angle of the detection beam in the second direction.

[0074] The following describes the first embodiment of a beam expander using a beam expander cylindrical lens group.

[0075] Please refer to Figure 3 as well as Figure 4 In this embodiment, the beam expander is a beam-expanding cylindrical lens group. The positive incident light path formed by this beam-expanding cylindrical lens group includes a second cylindrical lens 202 and a third cylindrical lens 203.

[0076] The aforementioned lateral normal incidence optical path is arranged in the side-view direction of objective lens 102. The laterally incident beam A2 first enters the beam expander group composed of the second cylindrical lens 202 and the third cylindrical lens 203, the curvatures of which are both located within the second direction shaping section. This beam expander group is set to a magnification of 1x. When the beam is collimated after passing through the third cylindrical lens 203, a radial spot of the base magnification is formed.

[0077] The incident light beam, after being shaped into parallel light in the first direction (X-axis) by the second cylindrical lens 202 and the third cylindrical lens 203, is converged onto the wafer surface by the lens assembly 103 and forms a light spot on the surface under test. The light spot has a first size related to the first direction. The incident light beam, after being shaped into non-parallel light in the second direction (Y-axis) by the second cylindrical lens 202 and the third cylindrical lens 203, is converged onto the wafer surface by the lens assembly 103 and further forms the shape of the aforementioned light spot in another direction on the surface under test. This light spot has a second size related to the second direction, which is perpendicular to the first direction.

[0078] The distance between the second cylindrical lens 202 and the third cylindrical lens 203 is adjustable, which can change the incident beam angle θ of the second-direction detection beam. Similarly, in this embodiment, when the incident beam angle θ increases, the size of the beam illuminating the lens assembly increases. It also increases due to the second size of the light spot. There is a tangent function relationship between the incident beam angle θ and the incident beam angle θ. The second size of the light spot As the angle of the incident beam is adjusted, the beam angle increases accordingly, thus achieving both avoidance of lens damage and high detection yield. Simultaneously, the lens curvature is located in the second direction section, having virtually no impact on the spot parameters in the first direction, thus achieving high-sensitivity detection.

[0079] The fourth cylindrical lens 204 is used in conjunction with the lens assembly 103 for compound focusing, together forming a compound focusing system. The curvature of the fourth cylindrical lens 204 lies within the shaping section in the second direction. This compound focusing system has a specific radial focal length, ultimately forming a standard radial focused spot on the wafer surface.

[0080] The curvature of the fifth cylindrical lens 205 lies within the shaping section in the first direction and is orthogonal to the curvatures of the second cylindrical lens 202, the third cylindrical lens 203, and the fourth cylindrical lens 204. Specifically, the curvature of the fifth cylindrical lens 205 lies in the XOZ plane, where Z is the optical axis. The curvatures of the second cylindrical lens 202, the third cylindrical lens 203, and the fourth cylindrical lens 204 lie in the YOZ plane. The XOZ plane is the shaping section in the first direction, and the YOZ plane is the shaping section in the second direction. The XOZ plane and the YOZ plane are orthogonal to each other.

[0081] like Figure 5 As shown, the optical path shaping in the first direction is located in the top-view direction of the objective lens 102. The top-view incident laser beam A1 passes successively through the second cylindrical lens 202, the third cylindrical lens 203, and the fourth cylindrical lens 204. Since the lens curvatures of the second cylindrical lens 202, the third cylindrical lens 203, and the fourth cylindrical lens 204 are all located in the second direction section, they have virtually no effect on the parameters of the light spot in the first direction, and the parameters of the light spot emitted in the first direction are basically consistent with those of the original laser beam 201. In this embodiment, the lens curvatures of the second cylindrical lens 202 and the third cylindrical lens 203 work together in the second direction, having virtually no effect on the optical path in the first direction, thus enabling adjustment in both directions. However, this optical path introduces astigmatism between the light spots in the first and second directions, resulting in non-coincidence of focal points. The fifth cylindrical lens 205 is provided to compensate for astigmatism; its curvature acts on the first direction section and is orthogonal to the second cylindrical lens 202, the third cylindrical lens 203, and the fourth cylindrical lens 204. The fifth cylindrical lens 205 is translated along the optical axis to generate the collimated output light spot in the first direction. The light spot is reflected by prism 104 to lens assembly 103, and tangential focusing is achieved based on the tangential focal length of the lens assembly. The size of the light spot is typically controlled within the range of 3–5 micrometers.

[0082] Figure 6 This demonstrates a design that achieves a change in the size of the light spot in the second direction by adjusting the distance between the second cylindrical lens 202 and the third cylindrical lens 203. Figure 6 In the process, when the distance between the second cylindrical lens 202 and the third cylindrical lens 203 is P1, the output beam is collimated, forming a standard radial spot. When the distance is increased to P2, the output beam slightly converges, the focal point deviates from the wafer surface, and the spot size increases. Further increasing the distance between the second cylindrical lens 202 and the third cylindrical lens 203 to P3 or P4 can further enlarge the spot size to adapt to different yield detection requirements. Figure 6 In the embodiment shown, the size and focal length of the first direction light spot remain unchanged during the adjustment of the second direction light spot.

[0083] Please refer to Figure 4The side-directed incident light path shown can be further combined with the oblique incident light path 300, which uses an optical shaping element 301 to form an overall layout of forward and oblique incident light.

[0084] Please refer to Figure 7 As shown Figure 4 The specific implementation optical path of the overall layout with oblique incidence.

[0085] The positive incident light path of the lateral incident light path assembly forms a vertically incident beam through the beam splitter 104 inside the objective lens 102. The detection light source passes through the second cylindrical lens 202, the third cylindrical lens 203, the fourth cylindrical lens 204, the fifth cylindrical lens 205, the beam splitter 104, and the lens assembly 103, which mainly constitute the positive incident light path assembly, and forms a positive incident light spot on the wafer surface.

[0086] When combining the oblique incident light path, the side incident light path assembly includes a beam splitter 401 on the normal incident light path. The oblique incident light path includes a fifth reflecting mirror 408 and an optical shaping element 301. The detection light source passes through the beam splitter 401, the fifth reflecting mirror 408, and the optical shaping element 301, which mainly constitute the oblique incident assembly, and forms an oblique incident light spot on the wafer surface. This normal incident light spot and the oblique incident light spot together shape the shape of the light spot.

[0087] The light source emits a detection beam towards the wafer under test. After the beam is split by the beam splitter 401, part of the beam enters the normal incidence assembly to form a vertically incident beam. The other part enters the oblique incidence optical path to form an oblique incidence beam. In the oblique incidence optical path, the optical shaping element 301 is a beam expanding and shaping module, which can be a diffractive optical element (DOE), a freeform mirror, a microlens array, a cylindrical mirror, or any other suitable shaping module known in the art.

[0088] The following is a detailed introduction Figure 9 as well as Figure 10 The beam expander column lens group shown.

[0089] In this embodiment, the beam-expanding cylindrical lens group includes a first optical component and a second optical component. The first optical component is a cylindrical beam expander or a cylindrical beam expander group in a first direction, and the second optical component is a cylindrical beam expander or a cylindrical beam expander group in a second direction. The beam expander group can be Galilean or Keplerian.

[0090] A first optical component expands and shapes the incident beam in a first direction to form a parallel detection beam in the first direction. This beam is incident on lens assembly 36 and converged onto the wafer surface, forming a spot on the surface under test. The spot has a first size related to the first direction. A second optical component expands and shapes the incident beam to form a non-parallel detection beam in a second direction. This beam is incident on lens assembly 36 and converged onto the wafer surface, further forming the shape of the aforementioned spot in another direction on the surface under test. This spot has a second size related to the second direction, which is perpendicular to the first direction.

[0091] The following is an introduction Figure 9 The diagram shows the first orthogonal oblique incidence overall layout using a beam expander column lens group.

[0092] The incident beam 201 can be a circular or elliptical Gaussian collimated beam. The incident beam 201 passes through the second optical component 2, the first optical component 13, the first reflector 14, the second reflector 16, and the third optical component 17 to form an obliquely incident illumination beam, which forms an obliquely incident spot on the wafer surface 100. The incident beam 201 also passes through the second optical component 2, the first optical component 13, the first reflector 14, the third reflector 15, the internal reflecting element 31, and the lens assembly 36 of the objective lens 3 to form a normally incident illumination beam, which also forms a normally incident spot on the wafer surface 100. Both the normally and obliquely incident spots are the same size and in the same position.

[0093] Among them, the first optical component 13 and the second optical component 2 are cylindrical beam expanders or cylindrical beam expander groups.

[0094] In the standalone normal incidence embodiment, the incident beam 201 passes through the second optical component 2, the first optical component 13, the first reflector 14, the third reflector 15, the internal reflective element 31, and the lens assembly 36 constituting the normal incidence assembly, and forms a normal incidence spot on the surface to be tested. The position of the second optical component 2 can be changed, and it can be switched to the position of the second optical component 2'. This method enables independent adjustment of the radial spot size for normal and oblique incidence. After the position is switched, the detection light source passes through the first optical component 13, the first reflector 14, the third reflector 15, the second optical component 2', and the lens assembly 36 constituting the normal incidence assembly, and forms a normal incidence spot on the surface to be tested. During wafer inspection, the first optical component 13, in conjunction with the lens assembly 36, forms the normal incidence radial spot size, and the second optical component 2, in conjunction with the lens assembly 36, forms the normal incidence tangential spot size.

[0095] In the single oblique incidence embodiment, the detection light source passes through the second optical component 2, the first optical component 13, the first reflector 14, the second reflector 16, and the third optical component 17 that constitute the oblique incidence assembly, and forms an oblique incidence light spot on the surface to be tested.

[0096] The third optical component can be a spherical or aspherical lens group, which works with the first optical component 13 to form a light spot size in the oblique incidence direction and works with the second optical component 2 to form a light spot size in the oblique incidence direction.

[0097] The detection device in this embodiment includes a switching device. The switching device includes a motion mechanism, and a third reflector 15 is disposed on the motion mechanism. The third reflector 15 is used to switch between normal incident and oblique incident light paths. If a single oblique incident light path is frequently used, the movable third reflector 15 may not be necessary, which easily ensures the stability of the light path.

[0098] The first and second direction detection beams are incident on the internal reflecting element from above the lens assembly. The internal reflecting element 31 inside the objective lens 3 can be implemented in various ways, such as a reflecting prism or a right-angled triangular prism. For example, it can be... Figure 9 The reflecting prism 311 shown is made of two right-angled triangular prisms bonded together. Alternatively, a right-angled triangular prism, i.e., reflecting prism 312, can be used directly. Since the light beam is not incident perpendicularly to the surface of the internal reflecting element 31, the angle at which the incident light beam with a certain angle hits the bonded surface after being refracted by the reflecting prism 311 is smaller than the angle at which it hits the reflecting prism 312 directly, which is more conducive to maintaining the incident polarization state.

[0099] The first reflecting mirror 14 is positioned on the common optical path of the side-incident optical path assembly, and is driven by a first piezoelectric ceramic device 141 for autofocus. Because the spot light is small in the illumination area of ​​the wafer under test, the high-precision motion platform needs to maintain extremely high rotational speeds to ensure overall equipment throughput. To prevent instability in the defect signal caused by surface undulations during inspection, an autofocus device for rapid real-time adjustment of the spot position needs to be designed in the illumination optical path. Figure 9 In this design, a high-response-frequency piezoelectric ceramic device 141 (PZT) connected to a detection device is mounted on the first reflecting mirror 14 in the common optical path section for both oblique and orthogonal incidence. When the height undulations on the wafer surface cause the obliquely incident light spot to strike the non-optical axis of the objective lens, the high voltage drives the piezoelectric ceramic device 141 to correct the light spot back to the optical axis of the objective lens. By placing the first reflecting mirror 14 in the common optical path for both oblique and orthogonal incidence, and prioritizing ensuring that the oblique incident optical path adjustment meets the requirements, if the orthogonal incident optical path has a certain offset, the first reflecting mirror 14 can be finely adjusted to make the oblique and orthogonal incident light spots coincide, making optical path adjustment simpler and more efficient.

[0100] Furthermore, in embodiments where both normal and oblique incidence coexist, the third reflecting mirror 15 can be configured as a beam splitter. The first optical component 13 and the second optical component 2 are arranged in a common optical path. The detection light source passes through the second optical component 2, the first optical component 13, the first reflecting mirror 14, the third reflecting mirror 15, the internal reflecting element 31, and the lens assembly 36, which constitute the normal incidence component, and forms a normal incidence spot on the surface to be measured. Simultaneously, the detection light source passes through the second optical component 2, the first optical component 13, the first reflecting mirror 14, the third reflecting mirror 15, the second reflecting mirror 16, and the third optical component 17, which mainly constitute the oblique incidence component, and forms an oblique incidence spot on the surface to be measured. Alternatively, after the second optical component 2 is moved to the third reflector 15, the first optical component 13 is placed in the common optical path. The detection light source passes through the first optical component 13, the first reflector 14, the third reflector 15, the second optical component 2, the internal reflective element 31, and the lens assembly 36 that constitute the normal incidence component, forming a normal incidence light spot on the surface to be tested. At the same time, the detection light source passes through the first optical component 13, the first reflector 14, the third reflector 15, the second reflector 16, and the third optical component 17 that constitute the oblique incidence component, forming an oblique incidence light spot on the surface to be tested. The normal incidence light spot and the oblique incidence light spot are the same size.

[0101] Figure 9 The embodiment also includes a detector 107, which receives the signal light collected by the objective lens and forms an image within the detector to generate detection information. The detector may include, but is not limited to, a CCD detector, a TDI detector, a photomultiplier tube (PMT), an avalanche photodiode (APD), etc.

[0102] The following is an introduction Figure 10 The second oblique incidence overall layout is shown.

[0103] Figure 10 In the illustrated embodiment, the incident beam 201 can be a circular or elliptical Gaussian collimated beam. It passes through the second optical component 2, the first optical component 13, the polarizing beam splitter 34 (PBS), and the lens assembly to form a normally incident illumination beam, which then forms a normally incident spot on the wafer surface 100. Alternatively, the incident beam 201 passes through the second optical component 2, the first optical component 13, the polarizing beam splitter 34, the seventh cylindrical lens 54, the fourth reflecting mirror 55, and the sixth cylindrical lens 56 to form an obliquely incident illumination beam, which also forms an obliquely incident spot on the wafer surface 100. Both the normally and obliquely incident spots are of the same size and at the same position.

[0104] The first optical component 13 and the second optical component 2 can be beam expanders composed of cylindrical beam expanders or groups of cylindrical beam expanders. The beam expander can be Galilean or Keplerian, and its purpose is to adjust the radial and tangential beam divergence angles, respectively.

[0105] In the normally incident light path, the first optical component 13, in conjunction with the lens assembly 36, forms the normally incident radial light spot size, and the second optical component 2, in conjunction with the lens assembly 36, forms the normally incident tangential light spot size. In the obliquely incident light path, the first optical component 13, in conjunction with the seventh cylindrical lens 54, forms the obliquely incident radial light spot size, and the second optical component 2, in conjunction with the sixth cylindrical lens 56, forms the obliquely incident tangential light spot size.

[0106] A first half-wave plate 51 is provided on the common optical path of the normal incidence component and the oblique incidence component. The first half-wave plate 51 is rotatable to switch between the normal incidence component and the oblique incidence component. The function of the first half-wave plate 51 is to rotate the polarization direction of linearly polarized light to realize the mutual conversion between P-polarized light and S-polarized light. When the polarized light passing through the first half-wave plate 51 is P-polarized light, it passes through the polarizing beam splitter prism 34 (PBS) and then through the seventh cylindrical lens 54, the fourth reflecting mirror 55, and the sixth cylindrical lens 56 to form oblique incidence. When the polarized light passing through the first half-wave plate 51 is S-polarized light, it is reflected after reaching the polarizing beam splitter prism 34 to form perpendicular incidence.

[0107] Figure 10 The oblique incidence assembly of the embodiment also includes a second half-wave plate 52 and a quarter-wave plate 53 disposed after the polarizing beam splitter 34 for polarization adjustment. Since the polarization state of the beam passing through the polarizing beam splitter 34 in the oblique incidence path is P-linearly polarized light, it is necessary to add a second half-wave plate 52 and a quarter-wave plate 53 to adjust the P-linearly polarized light, S-linearly polarized light, and circularly polarized light in the oblique incidence path.

[0108] The fourth reflector 55 is driven by a second piezoelectric ceramic device 551 (PZT) for autofocus. The fourth reflector 55 driven by the second piezoelectric ceramic device is only placed in the oblique incident light path for autofocus.

[0109] Figure 10 The embodiment also includes a detector 107, which receives the signal light collected by the objective lens and forms an image within the detector to generate detection information. The detector may include, but is not limited to, a CCD detector, a TDI detector, a photomultiplier tube (PMT), an avalanche photodiode (APD), etc.

[0110] Oblique incident lighting is more sensitive to protruding defects, while normal incident lighting is more sensitive to pitting defects. Figure 7 , Figure 9 , Figure 10 The publicly available normal and oblique incident illumination schemes enable full coverage detection of different types of defects such as bumps and pits, avoiding missed detections of wafer defects.

[0111] Please refer to this as well. Figure 11The normally incident light spot and the obliquely incident light spot are offset by a set distance along the tangential direction of the wafer surface rotating 100°. In the direction of rotation of the test object, the normally incident light spot or the obliquely incident light spot that first illuminates the test surface is the secondary light spot, and the primary light spot that illuminates it after passing through the set distance is the main light spot, in order to avoid sweeping explosion.

[0112] The following describes the master / slave spot layout under wedge-less conditions.

[0113] The size of defects on the wafer surface is not limited to a small range; small and large defects may coexist. Generally, a high laser power is required to detect small defects, but this may result in large defects being blown up, causing the entire wafer to become contaminated and unusable.

[0114] Therefore, to prevent large-size defects from being destroyed by deep ultraviolet high-power lasers during wafer inspection, it is generally necessary to set up two laser spots, one strong and one weak. The weak spot is in front, also known as the slave spot; the strong spot is behind, also known as the master spot. In the counterclockwise embodiment (b), slave spot 309 and master spot 308 are set up. Large-size defects will first pass through the slave spot. When the scattering intensity signal exceeds the threshold, the illumination laser can be quickly turned off to ensure that the large-size defects are not destroyed by the master spot. Figure 10 In the illustrated embodiment, the generation of the light spot can be achieved without introducing a wedge. During optical path adjustment, the normally incident and obliquely incident illumination spots are tangentially offset by a set distance. Figure 11 The diagram shows the main light spot positioned to the right and the secondary light spot to the left. Power adjustment for normal and oblique incidence is achieved by rotating the angle of the first half-wave plate 51. When oblique incidence illumination is the primary method, it can be adjusted by... Figure 11 In method (a), the platform rotates clockwise, and particle 6 first passes through the normally incident main light spot 306, and then through the obliquely incident main light spot 307. When normally incident illumination is the primary method, it can be achieved through... Figure 11 In method (b), the motion platform is rotated counterclockwise to ensure that the wafer particle 6 first passes through the oblique incident light spot 309 and then through the normal incident main light spot 308, so as to pre-determine the particle size and skip large-sized particles.

[0115] exist Figure 10 The illustrated embodiment supports polarization control, autofocus, and spot overlap correction, improving system applicability and production efficiency. It also enables master / slave spot layout without a wedge, avoiding the need for large-size defect sweeping.

[0116] Please refer to Figure 12 This embodiment relates to an optical detection method, including:

[0117] Step 500: Emit the incident beam.

[0118] Step 510: Expand and shape the incident beam in the first direction to form a parallel detection beam in the first direction.

[0119] Step 511: On the test surface of the object to be tested, a detection beam in the first direction is focused by a lens assembly and a light spot is formed on the test surface. The light spot has a first size related to the first direction.

[0120] Step 520: Expand and shape the incident beam in the second direction to form a non-parallel second direction detection beam. The incident beam angle of the second direction detection beam on the lens assembly is adjustable. When the incident beam angle increases or decreases, the beam size of the second direction detection beam incident on the surface of the lens assembly increases or decreases synchronously.

[0121] Step 521: On the test surface of the object to be tested, the second direction detection beam is focused by the lens assembly and a light spot is formed on the test surface. The light spot has a second size related to the second direction. The second size changes positively with the adjustment of the incident beam angle. The second direction is perpendicular to the first direction.

[0122] As mentioned above, the relationship between the second dimension of the second-direction detection beam incident on the surface of the wafer under test and the incident beam angle (θ) is as follows:

[0123] ,in, The second dimension is the second dimension formed when the detection beam is incident on the surface to be measured in the second direction, f is the focal length of the lens assembly of the objective lens, and θ is the angle of the incident beam.

[0124] Please refer to Figure 11 The method also includes the following steps:

[0125] The normal incidence component is configured to form a normal incidence spot on the surface of the test object, and / or;

[0126] The oblique incidence component is set to form an oblique incidence spot on the surface of the object to be tested;

[0127] In the spot coincidence correction, the normally incident spot and the obliquely incident spot have the same spot size and position in the first and second directions, respectively.

[0128] To achieve a master-slave beam pattern, the normally incident beam and the obliquely incident beam are the same size in the first and second directions, but at different positions. These two beams are offset by a set distance along the rotational tangent of the object under test. In the rotational direction of the object, the normally incident beam or the obliquely incident beam that first illuminates the surface under test is the slave beam, and the normally incident beam or the obliquely incident beam that illuminates after passing through the set distance becomes the master beam, thus preventing blowouts.

[0129] As is well known, the size of defects on a wafer surface is not limited to a small range; both small and large defects may coexist. Generally, high laser power is required to detect small defects, but this could potentially destroy large defects, contaminating the entire wafer and rendering it unusable. Therefore, to prevent the high-power deep ultraviolet laser from destroying large defects during wafer inspection, two laser spots, one strong and one weak, are typically used. The weak spot is positioned forward, also known as the slave spot; the strong spot is positioned backward, also known as the master spot. Large defects will first pass through the slave spot. When the scattering intensity signal exceeds a threshold, the illumination laser is quickly shut off to ensure that the large defect is not destroyed by the master spot. The equipment typically incorporates a wedge in the illumination path to generate the slave spot. Figure 10 The illustrated embodiment can achieve the generation of a light spot without introducing a wedge, such as Figure 11 As shown. During optical path adjustment, the normally incident and obliquely incident illumination spots are intentionally offset by a certain distance along the tangential direction. Figure 11 The diagram shows the main beam spot positioned to the right and the secondary beam spot to the left. The power adjustment for normal and oblique incidence is achieved by rotating the first half-wave plate by 51 degrees. When oblique incidence illumination is the primary method, it can be adjusted by... Figure 11 The platform can be rotated clockwise in the manner described in (a); when the main illumination is positive incident light, it can be achieved through... Figure 11 In method (b), the motion platform is rotated counterclockwise to ensure that the particles pass through the secondary light spot first and then the main light spot, so as to determine the particle size and skip large particles.

[0130] Two overall optical path layout schemes for orthogonal and oblique incidence are proposed: supporting polarization control, autofocus, and spot overlap correction, thus improving system applicability and production efficiency. Furthermore, master / slave spot layouts can be achieved without a wedge, avoiding the need for large-size defect sweeping.

[0131] Please refer to this again. Figure 2 This embodiment relates to a detection device, which includes an optical path device, comprising a side-incident optical path assembly 200 and a lens assembly 103.

[0132] The lateral incident optical path assembly 200 is used to provide an incident beam. The incident beam is expanded and shaped in a first direction by a beam expander to form a parallel first-direction detection beam, and simultaneously expanded and shaped in a second direction to form a non-parallel second-direction detection beam, the second direction being perpendicular to the first direction.

[0133] The first direction detection beam is emitted through the lens assembly 103 onto the surface of the rotating test object, such as the surface of the wafer 101. A detection spot with a size determined in the first direction of rotation is formed. The second direction detection beam is emitted through the lens assembly 103 onto the surface of the test object, making the size of the second direction detection spot adjustable. The detection spot forms a signal light after passing through the surface of the test object.

[0134] Detector 107 is used to receive signal light and form detection information based on the signal light.

[0135] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An optical path device, characterized by comprising: Comprising: a side incidence optical path assembly including a detection light source for providing an incident light beam and an expander lens group for expanding and shaping the incident light beam in a first direction to form parallel first direction detection light beams and for expanding and shaping the incident light beam in a second direction to form non-parallel second direction detection light beams; and a lens assembly, wherein the first direction detection light beams exit the lens assembly to a surface of an object under test and form a spot on the surface of the object under test, the spot having a first dimension related to the first direction; the second direction detection light beams exit the lens assembly to the surface of the object under test and form the spot on the surface of the object under test, the spot having a second dimension related to the second direction, the second direction being perpendicular to the first direction; the expander lens group includes a cylindrical lens having a lens curvature in a shaping cross section of the second direction; a relationship between the second dimension and the incident beam angle is: wherein, for the second dimension, f is the focal length of the lens assembly, and Θ is the incident beam angle.

2. The optical path device according to claim 1, wherein the expander lens group is an expander cylindrical lens group including an expander cylindrical lens for adjusting the incident beam angle of the first direction detection light beams, and / or the expander cylindrical lens group further includes an expander cylindrical lens for adjusting the incident beam angle of the second direction detection light beams.

3. The optical path device of claim 2, wherein the expander cylindrical lens group includes a second cylindrical lens and a third cylindrical lens, a distance between the second cylindrical lens and the third cylindrical lens being adjustable for changing the incident beam angle of the second direction detection light beams, the second cylindrical lens and the third cylindrical lens having lens curvatures in the shaping cross section of the second direction, the second dimension changing with the adjustment of the incident beam angle.

4. The optical path device of claim 3, wherein: the side incidence optical path assembly further includes a fourth cylindrical lens for compound focusing with the lens assembly, the fourth cylindrical lens having a lens curvature in the shaping cross section of the second direction.

5. The optical path device of claim 4, wherein the side incidence optical path assembly further includes a fifth cylindrical lens for compensating for astigmatism, the fifth cylindrical lens having a lens curvature in a shaping cross section of the first direction, the lens curvature of the fifth cylindrical lens being orthogonal to the lens curvatures of the second cylindrical lens, the third cylindrical lens, and the fourth cylindrical lens.

6. The optical path device of claim 5, wherein the side incidence optical path assembly further includes a beam splitter and an optical shaping element, the detection light source passing through the second cylindrical lens, the third cylindrical lens, the fourth cylindrical lens, the fifth cylindrical lens, the beam splitter and the optical shaping element as an oblique incidence assembly and forming an oblique incidence spot on the surface of the object under test.

7. The optical path device of claim 6, wherein the side incidence optical path assembly further includes a beam splitter and an optical shaping element, the detection light source passing through the beam splitter and the optical shaping element as an oblique incidence assembly and forming an oblique incidence spot on the surface of the object under test.

8. An optical detection method, characterized by, Comprising: a detection light source for providing an incident light beam; an expander lens group for expanding and shaping the incident light beam in a first direction to form parallel first direction detection light beams; The beam expander group expands and shapes the incident light beam in a second direction to form a non-parallel second direction detection light beam, the second direction detection light beam is incident to the lens assembly at an adjustable incident light beam angle, when the incident light beam angle increases or decreases, the second direction detection light beam incident to the surface of the lens assembly synchronously increases or decreases in beam size; The first direction detection light beam is converged by the lens assembly on the surface of the object to be measured to form a light spot on the surface of the object to be measured, the light spot has a first size related to the first direction; The second direction detection light beam is converged by the lens assembly on the surface of the object to be measured to form the light spot on the surface of the object to be measured, the light spot has a second size related to the second direction, the second size positively changes with the adjustment of the incident light beam angle, the second direction is perpendicular to the first direction; The beam expander group includes a cylindrical lens, the lens curvature of the cylindrical lens is located in the shaping section of the second direction; The relationship between the second size and the incident light beam angle is: wherein, is the second dimension, f is the focal length of the lens assembly, and Θ is the incident beam angle.

9. The optical detection method of claim 8, wherein, a normal incidence assembly is arranged to form a normal incidence light spot on the surface of the object to be measured; and / or an oblique incidence assembly is arranged to form an oblique incidence light spot on the surface of the object to be measured; The normal incidence light spot and the oblique incidence light spot have the same size and the same position in the first direction and the second direction.

10. The optical detection method of claim 8, wherein, a normal incidence assembly is arranged to form a normal incidence light spot on the surface of the object to be measured; and / or an oblique incidence assembly is arranged to form an oblique incidence light spot on the surface of the object to be measured; The normal incidence light spot and the oblique incidence light spot have the same size but different positions in the first direction and the second direction; Wherein, the normal incidence light spot and the oblique incidence light spot are staggered by a set distance in the tangential direction of the rotation of the object to be measured, in the rotation direction of the object to be measured, the normal incidence light spot or the oblique incidence light spot first irradiated on the surface of the object to be measured is the from light spot, and the normal incidence light spot or the oblique incidence light spot irradiated after the set distance is the main light spot, so as to avoid sweep explosion.

11. A detection device, characterized by Comprising: The optical path device of any one of claims 1 to 7, the optical path device comprising a side incidence optical path assembly and a lens assembly, The side incidence optical path assembly is used to provide an incident light beam, the incident light beam is expanded and shaped in a first direction to form a parallel first direction detection light beam, and at the same time is expanded and shaped in a second direction to form a non-parallel second direction detection light beam, the second direction is perpendicular to the first direction, the first direction detection light beam is emitted by the lens assembly to the measured surface of the rotating object to be measured to form a detection light spot with a determined size in the rotating first direction, the second direction detection light beam is emitted by the lens assembly to the measured surface to adjust the second direction size of the detection light spot, and the detection light spot forms a signal light after passing through the measured surface; A detector is used to receive the signal light and form detection information according to the signal light.

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