A defect detection device

Abstract

The present invention discloses a defect detection device, which relates to the field of optical detection technology. The illumination optical system is configured to emit an illumination beam of P polarized light; the first polarizing prism is configured to be located on the optical path between the illumination optical system and the first quarter wave plate, and pass the illumination beam; the first quarter wave plate is configured to be located between the first polarizing prism and the object to be measured, and the reflected light beam reflected by the upper surface of the object to be measured, after passing through the first quarter wave plate again, becomes S polarized light, and is reflected by the first polarizing prism and projected to the imaging system; the lower optical path reflection component is configured to reflect the transmitted light beam that passes through the object to be measured and project it to the imaging system. The embodiment of the present invention realizes the simultaneous detection of defects on the upper and lower surfaces and internal defects of the object to be measured, diversifies the defect detection scheme, and improves the detection accuracy by combining detection in multiple ways.

Description

Technical Field

[0001] The present invention relates to the field of optical detection, and in particular to a defect detection device. Background Art

[0002] In the precision manufacturing industry, due to the complexity and diversity of production processes, minor local defects such as pores, scratches, and cracks may occur on the surface and inside of products during machine processing and manual operation, resulting in product defects. To ensure product yield, defect detection is particularly important.

[0003] Defect detection of the mask not only exists on the surface, but may also exist inside the mask. For defects existing inside the mask, it is sometimes necessary to know the spatial coordinates of the defects in order to achieve the purpose of precise positioning. At the same time, the commonly used implementation plans are relatively simple and it is difficult to take into account diversified detection methods. Summary of the Invention

[0004] An embodiment of the present invention provides a defect detection device to simultaneously detect defects on the upper and lower surfaces and internal defects of an object to be detected, thereby diversifying defect detection schemes and improving detection accuracy by combining detection in multiple ways.

[0005] An embodiment of the present invention provides a defect detection device, comprising an illumination optical system, a first polarizing prism, a first quarter-wave plate, an imaging system, and a lower light path reflection assembly;

[0006] The illumination optical system is configured to emit an illumination beam of P-polarized light during bright field illumination;

[0007] The first polarizing prism is configured to, during brightfield illumination, be located in an optical path between the illumination optical system and the first quarter-wave plate and pass the illumination beam;

[0008] The first quarter-wave plate is configured such that, under bright field illumination, it is located between the first polarizing prism and the object to be measured, and the reflected light beam reflected by the upper surface of the object to be measured is converted to S-polarized light after passing through the first quarter-wave plate again, and is reflected by the first polarizing prism and projected onto the imaging system;

[0009] The lower light path reflection component is configured to reflect the transmitted light beam passing through the object to be measured and project it onto the imaging system during bright field illumination.

[0010] Optionally, the lower light path reflection assembly includes a second quarter wave plate and a second polarizing prism, and the second quarter wave plate is located between the object to be measured and the second polarizing prism;

[0011] The second quarter wave plate is configured to convert the transmitted light beam into S-polarized light;

[0012] The second polarizing prism is configured to reflect the transmitted light beam and project it onto the imaging system during bright field illumination.

[0013] Optionally, the lower light path reflection component includes a lower light path reflector.

[0014] Optionally, the defect detection device further includes a first reflector, a second reflector, and an imaging reflective assembly;

[0015] The first reflector is located on the optical path between the first polarizing prism and the imaging reflective component, and is configured to project the reflected light beam to the imaging reflective component, and then project it to the imaging system through the imaging reflective component;

[0016] The second reflector is located on the optical path between the lower optical path reflective component and the imaging reflective component, and is configured to project the transmitted light beam to the imaging reflective component and then to the imaging system via the imaging reflective component.

[0017] Optionally, the imaging reflection component includes a right-angle reflector, and the right-angle reflector includes an upper reflective surface and a lower reflective surface;

[0018] The reflected light beam is reflected by the upper reflective surface and projected onto the imaging system;

[0019] The transmitted light beam is reflected by the lower reflecting surface and projected onto the imaging system.

[0020] Optionally, both the upper reflecting surface and the lower reflecting surface are coated with a reflective film.

[0021] Optionally, the imaging reflection assembly includes a reflective movable mirror, which is configured to reflect the reflected light beam to the imaging system at a first reflection angle and reflect the transmitted light beam to the imaging system at a second reflection angle.

[0022] Optionally, the optical path of the reflected light beam between the upper surface of the object to be measured and the imaging system is a first optical path;

[0023] The optical path of the transmitted light beam between the lower surface of the object to be measured and the imaging system is a second optical path;

[0024] The first optical length is equal to the second optical length.

[0025] Optionally, a motor is further included, and the motor is configured to drive the second reflector and at least one element in the lower light path reflective assembly to move up and down to achieve layer-by-layer imaging.

[0026] Optionally, the imaging reflective component includes a selective polarization prism, and the selective polarization prism includes an S-polarization reflective film and a P-polarization reflective film;

[0027] The lower light path reflection assembly includes a second quarter wave plate, a second polarizing prism and a first half wave plate, wherein the second quarter wave plate is located between the object to be measured and the second polarizing prism;

[0028] The second quarter-wave plate is configured to convert the transmitted light beam into S-polarized light;

[0029] The second polarizing prism is configured to reflect the transmitted light beam to the first half-wave plate during bright field illumination; the first half-wave plate is located on the optical path between the second polarizing prism and the second reflector, and is configured to convert the transmitted light beam from S-polarized light to P-polarized light.

[0030] Optionally, a wave plate moving device is further included, and the wave plate moving device is configured to move the second quarter wave plate or the first half wave plate out of the optical path when imaging the reflected light beam alone.

[0031] Optionally, a wave plate moving device and a second half wave plate are further included. When imaging the transmitted light beam alone, the second half wave plate is moved into the light path between the first polarizing prism and the first reflector.

[0032] Optionally, the wave plate moving device includes a support frame and a carrying plate arranged on the support frame;

[0033] The first end of the carrier plate is configured to carry a wave plate, and the second end of the carrier plate is provided with a through hole or an opaque metal plate.

[0034] Optionally, the first polarizing prism is further configured to be located outside the optical path between the illumination optical system and the first quarter-wave plate during dark field illumination.

[0035] Optionally, the lower surface of the object to be measured includes a patterned coating;

[0036] The illumination optical system is further configured to be located on a side of the lower surface of the object to be measured.

[0037] Optionally, the object to be measured includes a mask.

[0038] An embodiment of the present invention provides a defect detection device, comprising an illumination optical system, a first polarizing prism, a first quarter-wave plate, an imaging system, and a lower optical path reflective assembly. By utilizing the illumination optical system, the first polarizing prism, the first quarter-wave plate, and the imaging system, and the upper optical path optical system, defect detection can be achieved on the upper surface of an object to be tested. By utilizing the illumination optical system, the imaging system, and the lower optical path reflective assembly, and the lower optical path optical system, defect detection can be achieved on the lower surface of an object to be tested. Alternatively, internal defects of an object to be tested can be detected. This allows for simultaneous detection of defects on the upper and lower surfaces and internal surfaces of an object to be tested, diversifying defect detection solutions and improving detection accuracy through combined detection in multiple ways. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 1 is a schematic structural diagram of a defect detection device provided by an embodiment of the present invention;

[0040] Figure 2 It is a schematic diagram of the imaging area of ​​the upper and lower light path imaging in the imaging system;

[0041] Figure 3 is a structural diagram of another defect detection device provided by an embodiment of the present invention;

[0042] Figure 4 is a structural diagram of another defect detection device provided by an embodiment of the present invention;

[0043] Figure 5 is a structural diagram of another defect detection device provided by an embodiment of the present invention;

[0044] Figure 6 is a schematic diagram of the structure of a selective polarization prism;

[0045] Figure 7 is a structural diagram of another defect detection device provided by an embodiment of the present invention;

[0046] Figure 8 is a structural diagram of another defect detection device provided by an embodiment of the present invention;

[0047] Figure 9 It is a schematic diagram of the structure of the wave plate moving device;

[0048] Figure 10 is a structural diagram of another defect detection device provided by an embodiment of the present invention;

[0049] Figure 11 This is the imaging effect diagram of a local area of ​​the dark field detection image plane;

[0050] Figure 12 It is a structural schematic diagram of another defect detection device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0052] Figure 1 FIG. 1 is a schematic diagram of the structure of a defect detection device provided by an embodiment of the present invention. Figure 1 As shown, the defect detection device includes an illumination optical system 1, a first polarizing prism 2, a first quarter-wave plate 3, an imaging system 4 and a lower light path reflection component 5. The illumination optical system 1 is configured to emit a P-polarized light beam during bright field illumination. During dark field illumination, the illumination optical system 1 can emit a P-polarized light beam, an S-polarized light beam, or an unpolarized light beam. The first polarizing prism 2 is configured to be located on the optical path between the illumination optical system 1 and the first quarter-wave plate 3 during bright field illumination, and the first polarizing prism 2 passes the P-polarized light beam. Generally, the first polarizing prism 2 can reflect S-polarized light. The first quarter-wave plate 3 is configured to be located between the first polarizing prism 2 and the object to be measured 9 during bright field illumination. The reflected light beam reflected by the upper surface of the object to be measured 9 becomes S-polarized light after passing through the first quarter-wave plate 3 again. The reflected light beam of S-polarized light is reflected by the first polarizing prism 2 and projected onto the imaging system 4. The lower light path reflection component 5 is configured to reflect the transmitted light beam passing through the object to be measured 9 and project it to the imaging system 4 during bright field illumination. The bright field illumination realizes bright field detection.

[0053] For example, the wavelength of light emitted by the illumination optical system 1 can be infrared light, visible light, or ultraviolet light, depending on the requirements and detection accuracy. The shorter the wavelength, the higher the detection accuracy under the same conditions. The polarizing prism (including the first polarizing prism 2) in the embodiment of the present invention is a polarizing beam splitter prism.

[0054] Exemplarily, for the upper optical path optical system (i.e., the optical path of the reflected light beam), during bright field illumination, the illumination optical system 1 emits an illumination light beam of P-polarized light, and the first polarizing prism 2 can pass the illumination light beam of P-polarized light. The illumination light beam of P-polarized light becomes circularly polarized light after passing through the first quarter-wave plate 3. After the circularly polarized light is reflected by the upper surface of the object to be measured 9, it passes through the first quarter-wave plate 3 again and becomes a reflected light beam of S-polarized light. The reflected light beam of S-polarized light is reflected by the first polarizing prism 2 and is finally projected onto the imaging system 4. The reflected light beam is imaged by the imaging system 4, thereby realizing the detection of the reflected light beam of the object to be measured 9. Specifically, for example, defect detection of the upper surface of the object to be measured 9 can be realized.

[0055] Exemplarily, for the lower optical path optical system (i.e., the optical path of the transmitted light beam), during bright field illumination, the illumination optical system 1 outputs an illumination light beam of P-polarized light, which becomes circularly polarized light after passing through the first polarizing prism 2 and the first quarter-wave plate 3. After the circularly polarized light is irradiated onto the object to be measured 9, the portion that passes through the object to be measured 9 is the transmitted light beam. The transmitted light beam is reflected by the lower optical path reflection component 5 and is ultimately projected onto the imaging system 4. The transmitted light beam is imaged by the imaging system 4, thereby enabling detection of the transmitted light beam of the object to be measured 9. Specifically, for example, defect detection of the lower surface of the object to be measured 9 can be achieved. Alternatively, detection of internal defects of the object to be measured 9 can be achieved.

[0056] An embodiment of the present invention provides a defect detection device, which includes an illumination optical system 1, a first polarizing prism 2, a first quarter-wave plate 3, an imaging system 4, and a lower light path reflection component 5. By using the illumination optical system 1, the first polarizing prism 2, the first quarter-wave plate 3, and the imaging system 4, and utilizing the upper light path optical system, defect detection on the upper surface of the object to be tested 9 can be achieved. By using the illumination optical system 1, the imaging system 4, and the lower light path reflection component 5, and utilizing the lower light path optical system, defect detection on the lower surface of the object to be tested 9 can be achieved. Alternatively, detection of internal defects of the object to be tested 9 can be achieved. This allows for simultaneous detection of defects on the upper and lower surfaces and internal defects of the object to be tested 9, diversifies the defect detection scheme, and improves detection accuracy by combining detection in multiple ways.

[0057] For example, the illumination beam irradiates the object 9 to be tested, generating a reflected beam and a transmitted beam. The reflected beam and the transmitted beam are split into two upper and lower optical paths, and are imaged into the imaging system 4 respectively. This enables the defect detection device provided in this embodiment to detect defects on at least the upper and lower surfaces of the object 9 to be tested simultaneously, and defect distribution maps for the upper and lower surfaces can be obtained in the same test. This reduces the number of times the defect detection device needs to be moved and debugged, improves the efficiency of defect detection and energy utilization, and reduces costs.

[0058] Optional, reference Figure 1 The lower optical path reflection assembly 5 includes a second quarter-wave plate 51 and a second polarizing prism 52. The second quarter-wave plate 51 is located between the object to be measured 9 and the second polarizing prism 52. The second quarter-wave plate 51 is configured to convert the transmitted light beam into S-polarized light. The second polarizing prism 52 is configured to reflect the S-polarized transmitted light beam during bright field illumination and project the S-polarized transmitted light beam toward the imaging system 4.

[0059] For example, refer to Figure 1The circularly polarized light beam that passes through the object 9 is projected onto the second quarter-wave plate 51. After passing through the second quarter-wave plate 51, the circularly polarized light beam is converted into an S-polarized light beam. The S-polarized light beam is projected onto the second polarizing prism 52, where it is reflected and ultimately projected onto the imaging system 4.

[0060] Optional, reference Figure 1 The defect detection device further includes a first reflector 6, a second reflector 7, and an imaging reflective assembly 8. The first reflector 6 is located on the optical path between the first polarizing prism 2 and the imaging reflective assembly 8. The first reflector 6 is configured to project a reflected light beam onto the imaging reflective assembly 8. The reflected light beam is projected onto the imaging reflective assembly 8 via the imaging reflective assembly 8 to the imaging system 4. The second reflector 7 is located on the optical path between the lower optical path reflective assembly 5 and the imaging reflective assembly 8. The second reflector 7 is configured to project a transmitted light beam onto the imaging reflective assembly 8. The transmitted light beam is projected onto the imaging reflective assembly 8 to the imaging system 4 via the imaging reflective assembly 8.

[0061] Exemplarily, the lower optical path reflection assembly 5 includes a second quarter-wave plate 51 and a second polarizing prism 52, and the second reflector 7 is located on the optical path between the second polarizing prism 52 and the imaging reflective assembly 8. The second reflector 7 reflects the transmitted light beam of S-polarized light reflected by the second polarizing prism 52 to the imaging reflective assembly 8, and the imaging reflective assembly 8 then projects the transmitted light beam of S-polarized light into the imaging system 4.

[0062] Optionally, the imaging reflection assembly 8 includes a right-angle reflector 80, which includes an upper reflective surface and a lower reflective surface. The reflected light beam is reflected by the upper reflective surface and projected onto the imaging system 4. The transmitted light beam is reflected by the lower reflective surface and projected onto the imaging system 4.

[0063] Exemplarily, the upper reflective surface and the lower reflective surface of the right-angle reflector 80 are perpendicular.

[0064] Optionally, both the upper and lower reflective surfaces of the right-angle reflector 80 are coated with a reflective film. This allows the upper reflective surface to reflect the reflected light beam, and the lower reflective surface to reflect the transmitted light beam. Furthermore, coating the reflective film can improve the reflectivity of the reflected and transmitted light beams on the right-angle reflector 80.

[0065] The upper and lower surfaces of the object 9 to be measured can be imaged simultaneously by using the right-angle reflector 80 , and no motor control is required. That is, the upper and lower surfaces of the object 9 to be measured can be imaged simultaneously without configuring a motor for the right-angle reflector 80 . Figure 2 This is a schematic diagram of the imaging area of ​​the upper and lower light paths in the imaging system 4, refer to Figure 2The imaging circle 15 of the imaging system 4 includes an upper optical path imaging area 16 and a lower optical path imaging area 17. The upper optical path imaging area 16 and the lower optical path imaging area 17 are arranged at intervals. The upper optical path imaging area 16 and the lower optical path imaging area 17 can be two target surfaces of the same camera or two cameras.

[0066] Figure 3 This is a schematic diagram of another defect detection device provided by an embodiment of the present invention. Figure 3 The imaging reflection assembly 8 includes a reflection mirror 81. The reflection mirror 81 is configured to reflect the reflected light beam to the imaging system 4 at a first reflection angle, and reflect the transmitted light beam to the imaging system 4 at a second reflection angle.

[0067] For example, refer to Figure 3 The first reflection angle is an angle at which the reflected light beam reflected by the first reflector 6 can be reflected to the imaging system 4, and the second reflection angle is an angle at which the transmitted light beam reflected by the second reflector 7 can be reflected to the imaging system 4. When the movable reflector 81 is at the first reflection angle, the reflected light beam is reflected and enters the imaging system 4, while the transmitted light beam cannot enter the imaging system 4, and thus no image is formed. When the movable reflector 81 is at the second reflection angle, the transmitted light beam enters the imaging system 4, while the reflected light beam cannot enter the imaging system 4, and thus no image is formed. By controlling the angle of the movable reflector, the reflected light beam or the transmitted light beam can be incident on the imaging system 4 independently, so that the upper optical path optical system or the lower optical path optical system of the defect detection system can be selectively imaged.

[0068] Optional, reference Figure 3 , the optical path of the reflected light beam between the upper surface of the object to be measured 9 and the imaging system 4 is the first optical path. The optical path of the transmitted light beam between the lower surface of the object to be measured 9 and the imaging system 4 is the second optical path. The first optical path is equal to the second optical path. The reflected light beam carries the defect information of the upper surface of the object to be measured 9, and the image formed by it in the imaging system 4 is the image of the upper surface of the object to be measured 9, which means that the imaging system 4 is focused on the position of the upper surface of the object to be measured 9. The first optical path is equal to the second optical path, which means that when the imaging system 4 images the transmitted light beam, it is focused on the position of the lower surface of the object to be measured 9, that is, the image formed by the transmitted light beam in the imaging system 4 is the image of the lower surface of the object to be measured 9. If the upper and lower surfaces of the object to be measured 9 are to be detected, it is necessary to ensure that the optical paths of the upper and lower surfaces of the object to be measured 9 to the imaging system 4 are consistent during installation. No focusing action is required when switching the position of the reflecting mirror 81, and it is only necessary to ensure focusing during initial installation, which saves the re-focusing process after switching the reflecting mirror 81 and improves detection efficiency. When only the upper and lower surfaces of the object to be measured 9 are detected, the initial position is set to be equal to the first optical path and the second optical path. In other embodiments, the first optical path may not be equal to the second optical path.

[0069] Optional, reference Figure 3The defect detection device further includes a motor 10, which is configured to drive the second reflector 7 and at least one element (eg Figure 3 ) moves up and down to achieve layer-by-layer imaging. For example, the motor 10 drives the second reflector 7 and the second polarizing prism 52 to move upward, and the object plane corresponding to the image formed by the transmitted light beam through the object to be measured 9 in the imaging system 4 will move upward accordingly, thereby achieving detection of internal defects of the object to be measured 9. If the optimal focal plane of the lower optical path is located at a certain horizontal height within the body of the object to be measured 9, the motor 10 drives the second reflector 7 and the second polarizing prism 52 to move downward (before reaching the upper surface of the object to be measured, the motor 10 can drive the second reflector 7 and the second polarizing prism 52 to move up and down, and then, if necessary, achieve repeated scanning of a certain part inside the body of the object to be measured), then the object plane corresponding to the image formed by the transmitted light beam through the object to be measured 9 in the imaging system 4 will move downward accordingly.

[0070] For example, refer to Figure 3 First, the lower surface of the object 9 is imaged by focusing, with this position selected as the initial zero point (0,0,0). Then, the internal defect of the object 9 is imaged by moving motor 10. When the focus is clear, motor 10 will feedback the movement amount △h. The depth of the defect relative to the lower surface is z = 2n△h, where n is the refractive index of the object 9. The remaining two-dimensional coordinate information of the defect can be read from the imaging system 4, and the spatial coordinates of the defect can be obtained. The depth of the internal defect of the object 9 can be located.

[0071] Figure 3 The defect detection device shown uses a reflective movable mirror 81 to selectively image the upper or lower surface of the object 9 to be tested. Furthermore, as long as the first optical path is equal to the second optical path, switching the angle of the reflective movable mirror 81 does not require refocusing, thereby simplifying the operation process and improving detection efficiency. Furthermore, the motor 10 is configured to drive the second reflective mirror 7 and the second polarizing prism 52 to move up and down, changing the second optical path, thereby changing the imaging position of the imaging system 4 on the object 9 to be tested, achieving layer-by-layer imaging of the interior of the object 9 to be tested. This allows the defect detection device in this embodiment to selectively image the upper surface, lower surface, and interior of the object 9 to be tested, thereby achieving comprehensive defect detection of the object 9 to be tested.

[0072] Figure 4 This is a schematic diagram of the structure of another defect detection device provided by an embodiment of the present invention, referring to Figure 4 , the lower light path reflection component 5 includes a lower light path reflection mirror 54, the lower light path reflection mirror 54 replaces Figure 1 The second quarter wave plate 51 and the second polarizing prism 52 are arranged in the lower optical path reflector 54. The lower optical path reflector 54 directly reflects the transmitted light beam passing through the object to be measured 9 and projects it to the imaging system 4.

[0073] Figure 5 is a structural diagram of another defect detection device provided by an embodiment of the present invention, Figure 6 Schematic diagram of the structure of the selective polarization prism 82. Figure 5 and Figure 6 The imaging reflection component 8 includes a selective polarization prism 82, and the selective polarization prism 82 includes an S-polarization reflection film 11 and a P-polarization reflection film 12. The lower light path reflection component 5 also includes a first half-wave plate 53. The first half-wave plate 53 is located on the light path between the second polarization prism 52 and the second reflector 7. The first half-wave plate 53 is configured to change the transmitted light beam from S-polarized light to P-polarized light. The reflected light beam of S-polarized light reflected by the first polarization prism 2 is projected onto the selective polarization prism 82, and is reflected by the S-polarization reflection film 11 in the selective polarization prism 82 to the imaging system 4. The transmitted light beam of S-polarized light reflected by the second polarization prism 52 is converted into a transmitted light beam of P-polarized light after passing through the first half-wave plate 53. The transmitted light beam of P-polarized light is projected onto the selective polarization prism 82, and is reflected by the P-polarization reflection film 12 in the selective polarization prism 82 to the imaging system 4. The embodiment of the present invention uses a selective polarization prism 82 as the imaging reflection component 8, which can image the light beams of the upper and lower optical path optical systems into the same area of ​​the imaging system 4. Therefore, the imaging system 4 only needs to use one camera or one target surface to receive the light beams from the upper optical path optical system or the lower optical path optical system, thereby optimizing operations such as switching cameras, saving time and effort, and saving motor and software control costs.

[0074] For example, refer to Figure 5 and Figure 6 The selective polarization prism 82 is composed of four right-angle prisms. Figure 6 The selective polarization prism 82 includes an S-polarization reflective film 11 and a P-polarization reflective film 12. The S-polarization reflective film 11 reflects S-polarized light, while the P-polarization reflective film 12 reflects P-polarized light. If P-polarized light is incident from top to bottom, it is reflected to the right by the P-polarization reflective film 12 and prevented from entering the imaging system 4. If P-polarized light is incident from bottom to top, it is reflected to the left by the P-polarization reflective film 12 and enters the imaging system 4. The same applies to S-polarized light. Figure 5 When the defect detection device is working, the reflected light beam of the upper optical path optical system incident on the selective polarization prism 82 is S-polarized light, and the transmitted light beam of the lower optical path optical system incident on the selective polarization prism 82 is P-polarized light. Both will be reflected by the selective polarization prism 82 and enter the imaging system 4.

[0075] For example, refer to Figure 5The motor 10 is configured to drive the second reflecting mirror 7, the first half wave plate 53 and the second polarizing prism 52 to move up and down to achieve layer-by-layer imaging.

[0076] Figure 7 This is a schematic diagram of the structure of another defect detection device provided by an embodiment of the present invention, referring to Figure 7 , the lower light path reflection component 5 includes a lower light path reflection mirror 54, the lower light path reflection mirror 54 replaces Figure 5 The second quarter-wave plate 51, the first half-wave plate 53, and the second polarizing prism 52 are included in the lower optical path reflector 54. The lower optical path reflector 54 directly reflects the transmitted light beam that passes through the object to be measured 9 and projects it to the imaging system 4. It will be understood that when the lower optical path reflective assembly 5 includes the lower optical path reflector 54, the motor 10 can be configured to drive the second reflector 7 and the lower optical path reflector 54 to move up and down to achieve layer-by-layer imaging.

[0077] Optional, reference Figure 5 The defect detection device also includes a wave plate moving device. The wave plate moving device is Figure 5 The wave plate moving device is not shown in the figure, and will be described in detail later. The wave plate moving device is configured to move the second quarter wave plate 51 or the first half wave plate 53 out of the optical path when imaging the reflected light beam alone.

[0078] For example, refer to Figure 5 If the second quarter-wave plate 51 or the first half-wave plate 53 is removed from the optical path, the light beam reaching the selective polarization prism 82 is S-polarized light. The S-polarized light will be reflected to the right by the selective polarization prism 82 and cannot reach the imaging system 4, thereby achieving imaging of the upper optical path optical system alone. The lower optical path optical system is not imaged.

[0079] Figure 8 This is a schematic diagram of the structure of another defect detection device provided by an embodiment of the present invention, referring to Figure 8 , the defect detection device also includes a wave plate moving device ( Figure 8 (not shown) and the second half wave plate 55. When imaging the transmitted light beam alone, the second half wave plate 55 is moved into the light path between the first polarizing prism 2 and the first reflecting mirror 6.

[0080] For example, refer to Figure 8 The second half-wave plate 55 converts the incident S-polarized light into P-polarized light. When imaging of the reflected light beam is not required, the second half-wave plate 55 is moved into the optical path by operating the wave plate moving device. The reflected S-polarized light beam in the upper optical path optical system is converted to P-polarized light by the second half-wave plate 55. The selective polarization prism 82 reflects the P-polarized light incident from above to the right, thereby preventing the light beam in the upper optical path optical system from being imaged, thereby achieving independent imaging of the transmitted light beam.

[0081] The wave plate moving device can move the wave plate in and out of the optical path, thereby controlling the propagation direction of light, so that the upper optical path optical system or the lower optical path optical system can be imaged separately in the imaging system 4, or the upper optical path optical system or the lower optical path optical system can be imaged simultaneously, making the defect detection system more flexible.

[0082] Figure 9 This is a schematic diagram of the structure of the wave plate moving device, refer to Figure 9 The defect detection device includes a wave plate moving device 50. The wave plate moving device 50 includes a support frame 13 and a carrier plate 14 disposed on the support frame. The first end of the carrier plate 14 is configured to support a wave plate, which can be, for example, the second quarter wave plate 51, the first half wave plate 53, or the second half wave plate 55 in the above-mentioned embodiment. Figure 9 In this example, the first half-wave plate 53 is used as the wave plate. A through hole 56 is defined at the second end of the carrier plate 14. Therefore, when a wave plate is needed to alter the polarization state of the light beam, the first end of the carrier plate 14 is placed in the light path. When a wave plate is not needed to alter the polarization state of the light beam, the through hole 56 at the second end of the carrier plate 14 is placed in the light path.

[0083] For example, refer to Figure 5 and Figure 9 The first half-wave plate 53 is moved out of the optical path by the wave plate moving device 50. The transmitted light beam reaching the selective polarization prism 82 is then S-polarized light, which is reflected to the right by the selective polarization prism 82 and prevents it from reaching the imaging system 4. This allows the upper optical path optical system to be imaged separately, while the lower optical path optical system is not imaged.

[0084] In other embodiments, an opaque metal plate is disposed at the second end of the carrier plate 14. Specifically, the opaque metal plate is positioned at the location of the through hole 56. This shields the transmitted light beam from the lower optical path optical system, preventing it from reaching the selective polarization prism 82 and the imaging system 4. This also prevents imaging of the lower optical path optical system.

[0085] Figure 10 is a structural diagram of another defect detection device provided by an embodiment of the present invention, Figure 10 Some components are omitted, such as the first quarter wave plate 3. Figure 1 and Figure 10 The first polarizing prism 2 is further configured to be located outside the optical path between the illumination optical system 1 and the first quarter-wave plate 3 during dark field illumination. As a result, the first polarizing prism 2 does not reflect the specular reflection light ( Figure 10 The second polarizing prism 52 is not on the propagation path of the transmitted light (reflected light shown by the dotted line in the middle) of the illumination light beam of the illumination optical system 1. Figure 10 The defect detection device provided by the embodiment of the present invention can realize dark field illumination detection in addition to bright field illumination detection.

[0086] For example, refer to Figure 10 The illumination optical system 1 is rotated by a certain angle α based on the above embodiment, so that the illumination beam of the illumination optical system 1 cannot directly enter the imaging system 4. When the illumination beam emitted by the illumination optical system 1 hits the defect of the object to be tested 9, diffraction and scattering will occur, and the propagation direction of the scattered light and diffracted light will be changed. The scattered light and diffracted light are reflected by the first polarizing prism 2 and / or the second polarizing prism 52 and enter the imaging system 4 for imaging, thereby realizing dark field defect detection of the object to be tested 9. Among them, dark field illumination realizes dark field detection.

[0087] For example, refer to Figure 10 , the illumination optical system 1, in dark field illumination, the illumination optical system 1 can emit a P-polarized light beam, an S-polarized light beam, or a non-polarized light beam.

[0088] Optional, reference Figure 10 The first polarizing prism 2 and the second polarizing prism 52 can be replaced by plane mirrors to increase the reflectivity of the reflected light to about twice that of when polarizing prisms (including the first polarizing prism 2 and the second polarizing prism 52) are used.

[0089] Figure 11 This is the imaging effect diagram of the local area of ​​the dark field detection image plane, reference Figure 11 , Figure 11 The white dots circled in the middle are defects of the object to be tested 9.

[0090] It is understandable that when performing dark field detection, at least one of the wave plates (eg, the first quarter-wave plate 3 ) may be moved out of the light path.

[0091] Figure 12 This is a schematic diagram of the structure of another defect detection device provided by an embodiment of the present invention, referring to Figure 12 , the lower surface of the object to be measured 9 includes a patterned coating ( Figure 12 (not shown) The illumination optical system 1 is further configured to be located on one side of the lower surface of the object to be measured 9. A portion of the object to be measured 9 is opaque. For example, the lower surface of the object to be measured 9 may be chrome-plated, and the chrome-plated layer may be patterned. The patterned layer includes a light-transmitting region and an opaque region.

[0092] The illumination optical system 1 is rotated by a certain angle so that the illumination beam emitted by it directly hits the lower surface of the object 9 to be tested. Thus, based on the above embodiments, defects such as dust in the opaque area of ​​the object 9 to be tested can be further detected.

[0093] For example, refer to Figure 12 When the illumination optical system 1 is arranged on the lower surface side of the object 9, it can be applied as follows: Figure 12 In other embodiments, the illumination optical system 1 is disposed on the lower surface of the object 9 , which can also be applied to bright field illumination.

[0094] Optionally, the object to be tested 9 includes a mask. In other embodiments, the object to be tested 9 may also include other objects besides the mask, such as a glass plate with a pattern. Alternatively, at least one of the above-mentioned embodiments of the present invention may be applied to wafer inspection.

[0095] In summary, the defect detection device can detect defects on both the upper and lower surfaces of the mask, as well as internal defects, depending on actual conditions and needs. For internal defect detection, the spatial coordinates of the defects can be simultaneously located. For surface and internal defects, simultaneous or separate detection options are available. This flexible and versatile approach significantly simplifies system operation and reduces costs. Furthermore, the system can switch between brightfield and darkfield detection, a simple switching scheme achieved through a simple mechanical device.

[0096] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious variations, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of the present invention. Therefore, while the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention.

Claims

1. A defect detection device, characterized in that: It includes an illumination optical system, a first polarizing prism, a first quarter-wave plate, an imaging system and a lower light path reflection component; The illumination optical system is configured to emit an illumination beam of P-polarized light; The first polarizing prism is configured to be located on an optical path between the illumination optical system and the first quarter-wave plate and to pass the illumination light beam; The first quarter-wave plate is configured to be located between the first polarizing prism and the object to be measured, so that the reflected light beam reflected by the upper surface of the object to be measured is converted into S-polarized light after passing through the first quarter-wave plate again, and is reflected by the first polarizing prism and projected onto the imaging system; The lower light path reflection component is configured to reflect the transmitted light beam passing through the object to be measured and project it onto the imaging system; The lower light path reflection assembly includes a second quarter wave plate and a second polarizing prism, and the second quarter wave plate is located between the object to be measured and the second polarizing prism; The second quarter-wave plate is configured to convert the transmitted light beam into S-polarized light; The second polarizing prism is configured to reflect the transmitted light beam and project it onto the imaging system; Also included are a first reflector, a second reflector, and an imaging reflective assembly; The first reflector is located on the optical path between the first polarizing prism and the imaging reflective component, and is configured to project the reflected light beam to the imaging reflective component, and then project the reflected light beam to the imaging system through the imaging reflective component; The second reflector is located on the optical path between the lower optical path reflective component and the imaging reflective component, and is configured to project the transmitted light beam to the imaging reflective component and then project it to the imaging system through the imaging reflective component; The imaging reflective assembly includes a selective polarization prism, and the selective polarization prism includes an S-polarization reflective film and a P-polarization reflective film; The lower light path reflection assembly includes a second quarter wave plate, a second polarizing prism and a first half wave plate, wherein the second quarter wave plate is located between the object to be measured and the second polarizing prism; The second quarter-wave plate is configured to convert the transmitted light beam into S-polarized light; The second polarizing prism is configured to reflect the transmitted light beam to the first half-wave plate; the first half-wave plate is located on the optical path between the second polarizing prism and the second reflector, and is configured to convert the transmitted light beam from S-polarized light to P-polarized light.

2. The defect detection device according to claim 1, characterized in that The lower light path reflection component includes a lower light path reflection mirror.

3. The defect detection device according to claim 1, characterized in that: The imaging reflection assembly includes a right-angle reflector, and the right-angle reflector includes an upper reflective surface and a lower reflective surface; The reflected light beam is reflected by the upper reflective surface and projected onto the imaging system; The transmitted light beam is reflected by the lower reflecting surface and projected onto the imaging system.

4. The defect detection device according to claim 3, characterized in that: The upper reflecting surface and the lower reflecting surface are both coated with a reflective film.

5. The defect detection device according to claim 1, characterized in that: The imaging reflection component includes a reflective mirror, which is configured to reflect the reflected light beam to the imaging system at a first reflection angle and reflect the transmitted light beam to the imaging system at a second reflection angle.

6. The defect detection device according to claim 1, characterized in that: The optical path of the reflected light beam between the upper surface of the object to be measured and the imaging system is a first optical path; The optical path of the transmitted light beam between the lower surface of the object to be measured and the imaging system is a second optical path; The first optical length is equal to the second optical length.

7. The defect detection device according to claim 1, characterized in that: It also includes a motor, which is configured to drive the second reflector and at least one element in the lower light path reflective assembly to move up and down to achieve layer-by-layer imaging.

8. The defect detection device according to claim 1, characterized in that: It also includes a wave plate moving device, which is configured to move the second quarter wave plate or the first half wave plate out of the optical path when imaging the reflected light beam alone.

9. The defect detection device according to claim 1, characterized in that: It also includes a wave plate moving device and a second half-wave plate. When imaging the transmitted light beam alone, the second half-wave plate is moved into the light path between the first polarizing prism and the first reflector.

10. The defect detection device according to claim 8 or 9, characterized in that: The wave plate moving device includes a support frame and a carrying plate arranged on the support frame; The first end of the carrier plate is configured to carry a wave plate, and the second end of the carrier plate is provided with a through hole or an opaque metal plate.

11. The defect detection device according to claim 8 or 9, characterized in that: The first polarizing prism is further configured to be located outside the optical path between the illumination optical system and the first quarter-wave plate during dark field illumination.

12. The defect detection device according to claim 1, wherein: The lower surface of the object to be measured includes a patterned coating; The illumination optical system is further configured to be located on a side of the lower surface of the object to be measured.

Images