Optical assembly, overlay alignment equipment and two-mirror exposure system
By using an overlay alignment device to achieve precise alignment of alignment elements through interference fringes of diffraction beams, the problem of multi-layer exposure in two-mirror lithography exposure systems has been solved, thus improving the production capacity of lithography technology.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-03
- Publication Date
- 2026-03-10
AI Technical Summary
Existing two-mirror lithography exposure systems lack alignment equipment, making it impossible to achieve multi-layer exposure and limiting their practical value.
An overlay alignment device is provided, including a light source, a first alignment element, a two-mirror module, a second alignment element, a reflector, and an image processing module. By generating and processing the interference fringes of the diffracted beam, the device achieves precise alignment of the first and second alignment elements and supports double-layer exposure.
It achieves high-precision alignment, upgrades the traditional two-mirror exposure system, supports multi-layer exposure, and improves the production capacity of photolithography technology.
Smart Images
Figure CN121634736A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of photolithography technology, and in particular to an optical component, an overlay alignment device, and a two-mirror exposure system. Background Technology
[0002] Two-mirror systems are commonly used photolithography exposure systems, typically for use in photolithography prototypes. These prototypes are experimental devices used during the research and development phase to verify new concepts or improvements in photolithography technology. Photolithography equipment based on two-mirror systems can be used for the verification and development of core components such as photoresists and photomasks. However, the lack of alignment equipment limits the photolithography exposure system to single-layer exposure, restricting its practical value. Summary of the Invention
[0003] This application discloses an optical component, an overlay alignment device, and a two-mirror exposure system for achieving precise alignment of two-layer components.
[0004] To achieve the above objectives, this application provides the following technical solution:
[0005] In a first aspect, embodiments of this application provide an overlay alignment device, comprising: a light source, a first alignment element, a two-mirror module, a second alignment element, a workpiece stage, a reflector, and an image processing module;
[0006] The light source is used to generate illumination light toward the first alignment element;
[0007] The first alignment element is located on the object side of the two-mirror module, and the first alignment element has a first alignment mark for generating first diffraction light;
[0008] The second alignment element is mounted on the workpiece stage and located on the image side of the two-mirror module. The second alignment element has a second alignment mark for generating a second diffracted beam. The second diffracted beam includes a first diffracted beam and a second diffracted beam.
[0009] The reflector is located between the two-mirror module and the second alignment element, and is used to reflect the first diffraction beam.
[0010] The image processing module is configured to receive the second diffracted beam and the first diffracted beam from the mirror, and generate a displacement signal based on the interference fringes generated by the first diffracted beam and the second diffracted beam, so that the workpiece stage moves the second alignment element based on the displacement signal, so that the second alignment element and the first alignment element are aligned.
[0011] The aforementioned alignment equipment is used to align a first alignment element and a second alignment element, facilitating double-layer exposure. For example, the first alignment element can be an imaging element, and the second alignment element can be a wafer. A two-mirror module is located between the first and second alignment elements, with the first alignment element situated on the object side of the two-mirror module and the second alignment element on the image side. A light source is located on the side of the first alignment element opposite to the two-mirror module, used to generate illumination light. Both the first and second alignment elements have alignment marks for alignment, namely a first alignment mark and a second alignment mark. Irradiation light incident on the first alignment mark generates first diffracted light. This first diffracted light, after passing through the two-mirror module and incident on the second alignment mark, generates second diffracted light. The second diffracted light includes a first diffracted beam and a second diffracted beam. The first diffracted beam is reflected by a mirror to the image processing module, and the second diffracted beam is directly incident on the image processing module. The first and second diffracted beams generate interference fringes and are imaged on the image processing module. The image processing module adjusts the position of the second alignment mark according to the position of the interference fringes, specifically by controlling the movement of the workpiece stage to adjust the position of the second alignment element. When the interference fringes are in the preset position, the image processing module determines that the first alignment mark and the second alignment mark are aligned, that is, the first alignment element and the second alignment element have completed the alignment adjustment.
[0012] The overlay alignment equipment provided in this application embodiment can be used to upgrade the traditional two-mirror exposure system to achieve high-precision alignment of multi-layer exposure, thereby providing a better platform for my country to study how to improve lithography technology to produce high-end chips.
[0013] In some embodiments, the first alignment mark includes at least two sets of gratings, wherein two sets of gratings are oriented perpendicularly.
[0014] And / or, the second alignment mark includes at least two sets of gratings, two of which are oriented perpendicularly.
[0015] In some embodiments, there are at least three first alignment markers, and the three first alignment markers are arranged in a triangle.
[0016] And / or, the second alignment marker is at least three, and the three first alignment markers are arranged in a triangle.
[0017] In some embodiments, the first diffracted light includes a first sub-diffracted light and a second sub-diffracted light having an angle between them; the first sub-diffracted light is focused by the two-mirror module and then incident on the second alignment mark to form the first diffracted beam; the second sub-diffracted light is focused by the two-mirror module and then incident on the second alignment mark to form the second diffracted beam.
[0018] In some embodiments, the two-mirror module includes a first reflective element, a second reflective element, and a third reflective element; the second reflective element and the third reflective element are located on both sides of the first reflective element;
[0019] The first reflective element is used to reflect the first sub-diffracted light to the second reflective element, and also to reflect the second sub-diffracted light to the third reflective element;
[0020] The second reflective element is used to reflect the first sub-diffraction light to the second alignment mark, and the third reflective element is used to reflect the second sub-diffraction light to the second alignment mark.
[0021] In some embodiments, the overlay alignment device further includes a lens group located between the image processing module and the second alignment element for focusing the first diffraction beam and the second diffraction beam.
[0022] In some embodiments, the operating wavelength of the overlay alignment device is less than or equal to 100 nm.
[0023] In some embodiments, the illumination light is visible light.
[0024] Secondly, embodiments of this application also provide a two-lens exposure system, including the overlay alignment device as described in any one of the embodiments of the first aspect.
[0025] Thirdly, embodiments of this application also provide an optical component for an overlay alignment device, comprising:
[0026] A first alignment element is provided with a first alignment mark to generate a first diffracted light based on the incident light;
[0027] A two-mirror module is disposed along the optical path with the first alignment element to generate reflected light based on the first diffracted light, wherein the first alignment element is located on the object side of the two-mirror module;
[0028] A second alignment element, located on the image side of the two-mirror module, and provided with a second alignment mark, generates a second diffracted beam based on the reflected light, wherein the second diffracted beam includes a first diffracted beam and a second diffracted beam; and
[0029] A reflector, located between the two mirror modules and the second alignment element, is used to reflect the first diffracted beam so that both the first and second diffracted beams propagate in a designated direction. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of the structure of an overlay alignment device provided in an embodiment of this application;
[0031] Figure 2 A schematic diagram of the optical path of an overlay alignment device provided in an embodiment of this application;
[0032] Figure 3 A schematic diagram of a first alignment mark or a second alignment mark in an overlay alignment device provided in an embodiment of this application;
[0033] Figure 4 A schematic diagram of a first alignment mark or a second alignment mark in another overlay alignment device provided in an embodiment of this application;
[0034] Figure 5 This is a schematic diagram showing the arrangement of the first alignment marks in the first alignment element provided in an embodiment of this application;
[0035] Figure 6 This is a schematic diagram illustrating the principle of stripe alignment adjustment in the horizontal direction;
[0036] Figure 7 A schematic diagram illustrating the principle of stripe alignment adjustment in the vertical direction;
[0037] Icons: 1-Light source; 2-First alignment element; 3-Two-mirror module; 4-Second alignment element; 5-Workpiece stage; 6-Reflector; 7-Lens group; 8-Image processing module; 11-Illumination light; 21-First alignment mark; 22-First diffraction light; 31-First reflection element; 32-Second reflection element; 33-Third reflection element; 41-Second alignment mark; 42-Second diffraction light; 43-Interference fringe; 44-Alignment fringe; 221-First sub-diffraction light; 222-Second sub-diffraction light; 421-First diffraction beam; 422-Second diffraction beam. Detailed Implementation
[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. In the description of the embodiments of this application, unless otherwise stated, " / " means "or", for example, A / B can mean A or B; "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships, for example, A and / or B can represent: A alone, A and B at the same time, and B alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.
[0039] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.
[0040] Figure 1 This is a schematic diagram of the structure of an overlay alignment device provided in an embodiment of this application. Figure 2 This is the optical path diagram for the overlay alignment equipment. (Example:) Figures 1 to 2 As shown, this application embodiment provides an overlay alignment device, including: a light source 1, a first alignment element 2, a two-mirror module 3, a second alignment element 4, a workpiece stage 5, a reflector 6, and an image processing module 8;
[0041] Light source 1 is used to generate illumination light 11 toward the first alignment element 2;
[0042] The first alignment element 2 is located on the object side of the two mirror modules 3. The first alignment element 2 has a first alignment mark 21 for generating the first diffracted light 22.
[0043] The second alignment element 4 is mounted on the workpiece stage 5 and located on the image side of the two mirror modules 3. The second alignment element 4 has a second alignment mark 41 for generating a second diffracted light 42. The second diffracted light 42 includes a first diffracted beam 421 and a second diffracted beam 422.
[0044] The reflector 6 is located between the two mirror modules 3 and the second alignment element 4, and is used to reflect the first diffraction beam 421.
[0045] Image processing module 8 is used to receive the second diffracted beam 422 and the first diffracted beam 421 reflected from the mirror 6, and to generate a displacement signal based on the interference fringes generated by the first diffracted beam 421 and the second diffracted beam 422, so that the workpiece stage 5 moves the second alignment element 4 based on the displacement signal, so that the second alignment element 4 and the first alignment element 2 are aligned.
[0046] The aforementioned alignment device is used to align the first alignment element 2 and the second alignment element 4, facilitating double-layer exposure. For example, the first alignment element 2 can be an imaging element, and the second alignment element 4 can be a wafer. A two-mirror module 3 is located between the first alignment element 2 and the second alignment element 4. The first alignment element 2 is located on the object side of the two-mirror module 3, and the second alignment element 4 is located on the image side of the two-mirror module 3. A light source 1 is located on the side of the first alignment element 2 opposite to the two-mirror module 3, and is used to generate illumination light 11. This illumination light 11 can be light emitted directly from the light source or shaped light after shaping. Both the first alignment element 2 and the second alignment element 4 have alignment marks for alignment, namely a first alignment mark 21 and a second alignment mark 41. When the illumination light 11 is incident on the first alignment mark 21, it generates a first diffracted light 22. The first diffracted light 22 is then incident on the second alignment mark 41 via the two-mirror module 3, generating a second diffracted light 42. The second diffracted light 42 includes a first diffracted beam 421 and a second diffracted beam 422. The first diffracted beam 421 is reflected by the reflector 6 to the image processing module 8, and the second diffracted beam 422 is directly incident on the image processing module 8. The first diffracted beam 421 and the second diffracted beam 422 generate interference fringes 43, which are then imaged on the image processing module 8. The image processing module 8 adjusts the position of the second alignment mark 41 according to the position of the interference fringes 43, specifically by controlling the movement of the workpiece stage 5 to adjust the position of the second alignment element 4. When the interference fringes 43 are at a preset position, the image processing module 8 determines that the first alignment mark 21 and the second alignment mark 41 are aligned, meaning that the first alignment element 2 and the second alignment element 4 have completed the alignment adjustment.
[0047] The overlay alignment equipment provided in this application embodiment can be used to upgrade the traditional two-mirror exposure system to achieve high-precision alignment of multi-layer exposure, thereby providing a better platform for my country to study how to improve lithography technology to produce high-end chips.
[0048] In some embodiments, the operating wavelength of the overlay alignment device is less than or equal to 100 nm, and the operating wavelength of the two-mirror exposure system used in the overlay alignment device is less than or equal to 100 nm. Exemplarily, the operating wavelength of the overlay alignment device can be as short as the X-ray band. The overlay alignment device provided in this application embodiment can be applied to wavelengths of 10 nm to 100 nm.
[0049] In some embodiments, since the working wavelength of the two-mirror exposure system is less than or equal to 100 nm, the working wavelength of the overlay alignment device is the visible light wavelength, and the irradiation light 11 is visible light.
[0050] One possible approach is overlay alignment, which refers to the relative alignment between the imaging element and the wafer. Both the imaging element and the wafer have markings for overlay alignment, namely a first alignment mark 21 and a second alignment mark 41.
[0051] In some embodiments, such as Figure 3 As shown, the first alignment mark 21 includes at least two sets of gratings, and two of the at least two sets of gratings are perpendicular in direction;
[0052] And / or, the second alignment mark 41 includes at least two sets of gratings, of which two sets of gratings are oriented perpendicularly.
[0053] One possible way to achieve this is, such as Figure 3 As shown, the alignment marks include a horizontal grating and a vertical grating, with the two sets of gratings perpendicular to each other. The alignment marks are either a first alignment mark 21 or a second alignment mark 41.
[0054] One possible way to achieve this is, such as Figure 4 As shown, the alignment mark includes a set of vertical gratings and two sets of horizontal gratings, with the two sets of horizontal gratings spaced apart. It should be noted that of the two sets of horizontal gratings, one set is used in conjunction with the vertical gratings as the alignment mark, while the other set can serve as a redundant grating.
[0055] As is understandable, a grating, as an important optical element, is an optical diffraction device composed of a large number of equally spaced parallel slits or reflecting surfaces. The orientation of the grating can be the same as the arrangement of the parallel slits. The working principle of a grating is based on the phenomenon of light diffraction. Gratings can be used for spectral analysis; when light is incident on a grating, diffraction and interference occur, forming separated spectral lines. This is because light of different wavelengths is separated due to minute differences in diffraction angles. Gratings can also separate polychromatic light into monochromatic light.
[0056] It should be noted that, depending on the actual process requirements, the number of gratings in the alignment marks can be increased, generally at least two sets, corresponding to the two free directions of the plane.
[0057] In some embodiments, there are at least three first alignment markers 21, and the three first alignment markers are arranged in a triangle.
[0058] And / or, the second pair of markers 41 consists of at least three, with the three first pair of markers arranged in a triangle.
[0059] In one possible implementation, the imaging element and the wafer can have multiple alignment marks, typically at least three, to define a plane, such as... Figure 5 As shown. Figure 5 Three alignment marks can define a plane.
[0060] In some embodiments, such as Figure 1 and Figure 2As shown, the overlay alignment device also includes a lens group 7, located between the image processing module 8 and the second alignment element 4, for focusing the first diffraction beam 421 and the second diffraction beam 422. The lens group 7 can be a single lens or a lens group.
[0061] In some embodiments, the first diffracted light 22 includes a first sub-diffracted light 221 and a second sub-diffracted light 222 having an angle; the first sub-diffracted light 221 is focused by the two-mirror module 3 and incident on the second alignment mark 41 to form a first diffracted beam 421; the second sub-diffracted light 222 is focused by the two-mirror module 3 and incident on the second alignment mark 41 to form a second diffracted beam 422.
[0062] One possible way to achieve this is, such as Figure 2 As shown, the illumination light 11, after being incident on the first alignment mark 21 of the imaging element, generates a first diffracted light 22. The first diffracted light 22 includes a first sub-diffracted light 221 and a second sub-diffracted light 222 with an angle between them. The first diffracted light 22 passes through the two-mirror module 3 and then is incident on the second alignment mark 41 on the wafer to generate a second diffracted light 42. One beam of the second diffracted light 42 generated by the second alignment mark 41 is received by the lens group 7, and the other beam is also received by the lens group 7 after being reflected by the mirror 6. The two beams of second diffracted light 42 received by the lens group 7 have a certain angle between them, and after passing through the lens group 7, they form interference fringes 43, which are imaged on the image processing module 8.
[0063] A two-mirror exposure system includes a projection optics system that projects a shaped light beam onto a mask (or photomask) containing a miniature pattern of an integrated circuit design. This process often employs a high-precision lens group (sometimes including mirrors) to ensure the beam is accurately delivered to the silicon wafer surface. In this step, "two mirrors" does not refer to two simple lenses, but rather to the entire sophisticated multi-lens projection system, which may contain dozens or even hundreds of optical elements to achieve extremely high resolution and alignment accuracy.
[0064] In some embodiments, such as Figure 1 and Figure 2 As shown, the two-mirror module 3 includes a first reflective element 31, a second reflective element 32, and a third reflective element 33; the second reflective element 32 and the third reflective element 33 are located on both sides of the first reflective element 31.
[0065] The first reflective element 31 is used to reflect the first sub-diffraction light 221 to the second reflective element 32, and also to reflect the second sub-diffraction light 222 to the third reflective element 33;
[0066] The second reflective element 32 is used to reflect the first sub-diffraction light 221 to the second alignment mark 41, and the third reflective element 33 is used to reflect the second sub-diffraction light 222 to the second alignment mark 41.
[0067] like Figure 1 and Figure 2 As shown, the first reflective element 31, the second reflective element 32, and the third reflective element 33 form an inverted triangular structure; both mirror modules 3 are reflectors, and the reflecting surface of each mirror can be a freeform surface. The imaging element is on the object plane of the two mirror modules 3, and the two mirror modules 3 scale the pattern on the imaging element onto the wafer surface according to a certain ratio. For example, the first sub-diffraction light 221 and the second sub-diffraction light 222 of the first diffracted light 22 are incident on the reflecting surface of the first reflective element 31 through the gap between the second reflective element 32 and the third reflective element 33, respectively. Since the first sub-diffraction light 221 and the second sub-diffraction light 222 have an included angle, the first sub-diffraction light 221 and the second sub-diffraction light 222 are incident on different regions of the reflecting surface of the first reflective element 31. The first sub-diffraction light 221 is incident on the side of the first reflective element 31 facing the second reflective element 32, and the second sub-diffraction light 222 is incident on the side of the first reflective element 31 facing the third reflective element 33. Furthermore, the first sub-diffracted light 221, after being reflected by the second reflecting element 32, is incident on the second alignment mark 41, generating a first diffracted beam 421. The second sub-diffracted light 222, after being reflected by the third reflecting element 33, is incident on the second alignment mark 41, generating a second diffracted beam 422. The first diffracted beam 421, after being reflected by the reflecting mirror 6, is received by the lens group 7, and the second diffracted beam 422 is also received by the lens group 7. The first diffracted beam 421 and the second diffracted beam 422 form interference fringes 43 after passing through the lens group 7, and are imaged on the image processing module 8.
[0068] In some embodiments, the image processing module 8 has an alignment stripe 44 inside, and the image processing module 8 is used to control the movement of the workpiece stage 5 according to the positional offset between the interference stripe 43 and the alignment stripe 44. Figure 6 and Figure 7 The image processing module 8 generates alignment stripes 44 in both horizontal and vertical directions. The information of the alignment stripes 44 is recorded in the storage unit as a reference for alignment.
[0069] In one possible implementation, when there is an alignment misalignment between the imaging element and the wafer, the image processing module 8 generates offset interference fringes 43, such as... Figure 6 and Figure 7 As shown. Based on the direction of the deviation of interference fringe 43, the position of the wafer can be determined.
[0070] For example, such as Figure 6 As shown, the fringes need to be moved to the left. The position of the wafer can be adjusted by precisely moving the workpiece stage 5 so that the interference fringe 43 is aligned with the alignment fringe 44, thus aligning the relative position of the imaging element and the wafer. For example, as Figure 7As shown, the fringes need to be moved upwards. The position of the wafer can be adjusted by precisely moving the workpiece stage 5 so that the interference fringe 43 is consistent with the alignment fringe 44, that is, the relative position of the imaging element and the wafer can be aligned.
[0071] It should be noted that the specific movement of the workpiece stage 5 is determined by the imaging of the overlay optical path. Typically, the wafer's movement direction is parallel to the movement direction of the interference fringe 43.
[0072] This application proposes an overlay alignment device for a two-mirror exposure system, which can be used to upgrade a traditional two-mirror exposure system and achieve high-precision alignment of multi-layer exposure.
[0073] Secondly, embodiments of this application also provide a two-lens exposure system, including any of the overlay alignment devices as described in the first aspect embodiment.
[0074] The two-mirror exposure system provided in this application embodiment achieves high-precision alignment of the imaging element and the wafer through an overlay alignment device, thereby achieving high-precision alignment of multi-layer exposure.
[0075] Thirdly, embodiments of this application also provide an optical component for an overlay alignment device, comprising:
[0076] A first alignment element is provided with a first alignment mark to generate a first diffracted light 22 based on the incident light;
[0077] A two-mirror module is arranged along the optical path with a first alignment element to generate reflected light based on the first diffracted light, wherein the first alignment element is located on the object side of the two-mirror module;
[0078] A second alignment element, located on the image side of the two mirror modules, and equipped with a second alignment mark, generates a second diffracted beam based on reflected light. The second diffracted beam includes a first diffracted beam and a second diffracted beam.
[0079] A reflector, located between the two mirror modules and the second alignment element, is used to reflect the first diffracted beam so that both the first and second diffracted beams propagate in a designated direction.
[0080] The optical components provided in this application embodiment are used in an overlay alignment device, which can achieve high-precision alignment between imaging elements and wafers.
[0081] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this application without departing from the spirit and scope of this application. Therefore, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application also intends to include these modifications and variations.
Claims
1. A litho-etch overlay apparatus, characterized by, The overlay alignment device comprises: a light source, a first alignment element, a two-mirror module, a second alignment element, a workpiece table, a mirror and an image processing module; the light source is configured to generate illumination light towards the first alignment element; the first alignment element is located on the object side of the two-mirror module, and the first alignment element is provided with a first alignment mark for generating first diffraction light; the second alignment element is installed on the workpiece table and located on the image side of the two-mirror module, and the second alignment element is provided with a second alignment mark for generating second diffraction light; the second diffraction light comprises a first diffraction beam and a second diffraction beam; the mirror is located between the two-mirror module and the second alignment element, and is configured to reflect the first diffraction beam; the image processing module is configured to receive the second diffraction beam and the first diffraction beam from the mirror, to generate a displacement signal based on interference fringes generated by the first diffraction beam and the second diffraction beam, and to make the workpiece table move the second alignment element based on the displacement signal, so that the second alignment element and the first alignment element are aligned.
2. The overlay alignment apparatus of claim 1, wherein, The first alignment mark comprises at least two groups of gratings, and there are two groups of gratings with perpendicular directions in the at least two groups of gratings. And / or, the second alignment mark comprises at least two groups of gratings, and there are two groups of gratings with perpendicular directions in the at least two groups of gratings.
3. The overlay alignment apparatus of claim 1, wherein, The first alignment mark is at least three, and the three first alignment marks are arranged in a triangular shape. And / or, the second alignment mark is at least three, and the three first alignment marks are arranged in a triangular shape.
4. The overlay alignment apparatus of claim 1, wherein, The first diffraction light comprises first sub-diffraction light and second sub-diffraction light with an included angle; the first sub-diffraction light is incident on the second alignment mark after focusing through the two-mirror module to form the first diffraction beam; and the second sub-diffraction light is incident on the second alignment mark after focusing through the two-mirror module to form the second diffraction beam.
5. The overlay alignment apparatus of claim 4, wherein, The two-mirror module comprises a first reflecting element, a second reflecting element and a third reflecting element; the second reflecting element and the third reflecting element are located on both sides of the first reflecting element; the first reflecting element is configured to reflect the first sub-diffraction light to the second reflecting element and to reflect the second sub-diffraction light to the third reflecting element; the second reflecting element is configured to reflect the first sub-diffraction light to the second alignment mark, and the third reflecting element is configured to reflect the second sub-diffraction light to the second alignment mark.
6. The overlay alignment apparatus of claim 1, wherein, The overlay alignment device further comprises a lens group located between the image processing module and the second alignment element, configured to focus the first diffraction beam and the second diffraction beam.
7. The overlay alignment apparatus of any one of claims 1-6, wherein, The working wavelength band of the overlay alignment device is less than or equal to 100 nm.
8. The overlay alignment apparatus of any one of claims 1-6, wherein, The illumination light is visible light.
9. A two-mirror exposure system, characterized by, The overlay alignment device comprises the overlay alignment device according to any one of claims 1-8.
10. An optical component for an overlay alignment device, characterized in that, The overlay alignment device comprises: a first alignment element provided with a first alignment mark to generate first diffraction light based on incident light; a two-mirror module arranged along an optical path with the first alignment element to generate reflected light based on the first diffraction light, wherein the first alignment element is located on the object side of the two-mirror module; a second alignment element located at an image side of the two-mirror module and provided with a second alignment mark to generate second diffracted light based on the reflected light, wherein the second diffracted light comprises a first diffracted beam and a second diffracted beam; and a mirror located between the two-mirror module and the second alignment element to reflect the first diffracted beam so that the first diffracted beam and the second diffracted beam both propagate toward a predetermined direction.