Pupil detection device

Abstract

The invention relates to a pupil detection device which comprises a shell, an inner cavity is defined by the shell, a first through hole is formed in the shell, a covering window, a first support, a lens group, a second support and a scintillation crystal are arranged outside the inner cavity, the first support is fixed to the shell, the lens group is fixed to the first support, the second support is fixed to the lens group, and the scintillation crystal is fixed to the shell. The second support is provided with a second through hole, and the scintillation crystal is fixed on the second support and covers the second through hole. The covering window is fixed to the shell and / or the first support and covers the first through hole, a camera is arranged in the inner cavity, and the camera is fixedly connected with the shell; the scintillation crystal, the second through hole, the lens group, the covering window, the first through hole and the camera are sequentially arranged in the light transmission direction, the scintillation crystal is used for converting EUV light into fluorescent light, the lens group is used for amplifying and imaging the fluorescent light on the scintillation crystal, and the camera is used for shooting an image of the fluorescent light on the scintillation crystal. The pupil detection device disclosed by the invention can normally work in a vacuum environment, and can detect EUV (Extreme Ultraviolet) light.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing and detection technology, and more particularly to a pupil detection device. Background Art

[0002] In the photolithography process, the mask (also called the photomask) is a very critical component. Its main function is to accurately transfer the design pattern to the semiconductor wafer, thereby forming a tiny and precise circuit structure on the wafer surface. As the chip node shrinks, higher requirements are placed on the size of defects in the inspection mask.

[0003] Using synchrotron radiation as an EUV (extreme ultraviolet) light source can produce high-brightness and high-energy extreme ultraviolet light. High-brightness light sources can improve the signal-to-noise ratio of mask defect detection, allowing the system to have better sensitivity and resolution when detecting tiny defects. Many synchrotron radiation devices at home and abroad have conducted research on EUV mask defect detection systems. Existing synchrotron radiation devices all use Fourier synthesis illumination to improve the resolution of mask defect imaging.

[0004] Off-axis illumination is a typical Fourier synthesis method. MEMS (micro-electromechanical system) galvanometer is usually used for angle scanning. The ellipsoidal reflector is focused. The center point of the MEMS galvanometer is located at the first focus of the ellipsoidal reflector. The scanning light beam generated by the MEMS mirror converges to the second focus of the ellipsoidal reflector. The plane where the focus is located is the mask surface. Using the MEMS galvanometer for angle scanning can make the incident angle of the light deviate from the optical axis to enhance the high-frequency component of the illumination system, so as to enhance the resolution of the EUV mask defect detection system. By programming and controlling the angle scanning of the MEMS galvanometer, the light beam is scanned on the pupil plane according to a certain trajectory, and a variety of different types of illumination modes (such as annular illumination, dipole illumination, quadrupole illumination, etc.) can be created, so that the EUV mask defect detection system can more flexibly respond to the detection needs of different defects.

[0005] In order to ensure the performance of the pupil and enable the EUV mask defect detection system to achieve high-resolution imaging of mask defects, it is necessary to diagnose the synthetic illumination mode and its parameters such as light intensity uniformity, coherence factor, and incident angle. The image sensors used in the existing detectors for collecting pupil images are CCD or CMOS cameras, which generally cannot be used directly in a vacuum environment better than 1e-7torr. Finished vacuum cameras are expensive, large in size, and very difficult to install. Ordinary industrial cameras cannot work directly in a vacuum environment. First, it is difficult to dissipate heat through conventional convection and conduction heat dissipation in a vacuum. They mainly rely on thermal radiation to dissipate heat, which has low heat dissipation efficiency and is easy to damage; second, the industrial camera itself will release gas, destroying the vacuum environment of the EUV mask defect detection system; third, the spectral response range of most industrial cameras is 350nm to 1000nm, which does not include the EUV band.

[0006] Therefore, it is very necessary to develop a pupil detection device for EUV mask defect detection system that can work normally in a vacuum environment in order to improve the imaging resolution of the EUV mask defect detection system. Summary of the invention

[0007] The object of the present invention is to provide a pupil detection device which can work normally in a vacuum environment and collect pupil images of an EUV mask defect detection system.

[0008] Based on the above purpose, the present invention provides a pupil detection device, including a shell, the shell defining an inner cavity, a first through hole being opened on the shell, a cover window, a first bracket, a lens group, a second bracket and a scintillation crystal are arranged outside the inner cavity, the first bracket is fixed to the shell, the lens group is fixed to the first bracket, the second bracket is fixed to the lens group, a second through hole is arranged on the second bracket, the scintillation crystal is fixed to the second bracket and covers the second through hole; the cover window is fixed to the shell and / or the first bracket and covers the first through hole, a camera is arranged in the inner cavity, and the camera is fixedly connected to the shell; the scintillation crystal, the second through hole, the lens group, the cover window, the first through hole and the camera are arranged in sequence along the light transmission direction, the scintillation crystal is used to convert EUV light into fluorescence, the lens group is used to amplify and image the fluorescence on the scintillation crystal, and the camera is used to capture an image of the fluorescence on the scintillation crystal.

[0009] Furthermore, the lens group is detachably connected to the first bracket and the second bracket respectively, so as to adjust the distance between the lens group and the camera by adjusting the relative position between the lens group and the first bracket, and to adjust the distance between the lens group and the scintillation crystal by adjusting the relative position between the lens group and the second bracket.

[0010] Furthermore, the lens group is an achromatic lens group.

[0011] Furthermore, the top of the camera is fixedly connected to the housing, and a thermal pad is filled between the bottom of the camera and the inner wall of the housing.

[0012] Furthermore, a temperature sensor is provided at the bottom of the camera.

[0013] Furthermore, a conversion circuit board is also provided in the inner cavity, and the conversion circuit board includes a wire-to-board connector and a DB15 connector. The wire-to-board connector is electrically connected to the camera through a first wire, and is electrically connected to the temperature sensor through a second wire. A DB15 interface is provided on the outer shell, and the DB15 connector is plugged into the DB15 interface.

[0014] Furthermore, the material of the scintillation crystal is Ce:YAG, and the material of the cover window is sapphire.

[0015] Furthermore, a mark is engraved on the upper surface of the scintillation crystal.

[0016] Furthermore, a sealing ring is provided between the cover window and the shell.

[0017] Furthermore, it is applied to an EUV mask defect detection system, which includes a galvanometer, a reflector, an ellipsoidal reflector, a three-dimensional motion control console and a vacuum chamber, wherein the galvanometer, the reflector, the ellipsoidal reflector and the three-dimensional motion control console are all located in the vacuum chamber, the galvanometer is used to make EUV light emit at different angles, the reflector is used to reflect the EUV light emitted from the galvanometer onto the ellipsoidal reflector, and the ellipsoidal reflector is used to focus the EUV light onto one of the focal points of the ellipsoidal reflector, and the horizontal plane where the focus is located is used as the mask plane; the pupil detection device is arranged on the three-dimensional motion control console and is located directly below the mask plane.

[0018] The pupil detection device of the present invention can work in a vacuum chamber with a vacuum degree better than 1e-7torr, and detect the synthetic illumination mode in the EUV mask defect detection system. The design is compact and no structural modification of the EUV mask defect detection device is required for installation and use. The operating temperature of the camera is monitored by a temperature sensor to avoid damage due to excessive temperature, thereby improving the reliability of the pupil detection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a stereoscopic diagram of a pupil detection device according to an embodiment of the present invention after a scintillation crystal is removed;

[0020] Figure 2 is a right side view of a pupil detection device according to an embodiment of the present invention;

[0021] Figure 3 for Figure 2 AA section view;

[0022] Figure 4 is a schematic structural diagram of a switching circuit board of a pupil detection device according to an embodiment of the present invention;

[0023] Figure 5 is a schematic diagram of a pupil detection device according to an embodiment of the present invention when applied to an EUV mask defect detection system;

[0024] Figure 6 FIG. 4 is a schematic diagram showing a pupil detection device according to an embodiment of the present invention for detecting an incident angle of EUV light. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0026] like Figure 1 , Figure 2 and Figure 3 As shown, an embodiment of the present invention provides a pupil detection device, including a housing 100, a cover window 200, a first bracket 310, a lens group 320, a second bracket 330, a scintillation crystal 400 and a camera 500. The housing 100 defines an inner cavity 110, and a first through hole 120 is provided on the housing 100. The cover window 200, the first bracket 310, the lens group 320, the second bracket 330 and the scintillation crystal 400 are located outside the inner cavity 110. The first bracket 310 is fixed to the housing 100, the lens group 320 is fixed to the first bracket 310, the second bracket 330 is fixed to the lens group 320, the second bracket 330 is provided with a second through hole 331, and the scintillation crystal 400 is fixed to the second bracket 330 and covers the second through hole 331. The cover window 200 is fixed to the housing 100 and / or the first bracket 310 and covers the first through hole 120. The camera 500 is located in the inner cavity 110 and is fixedly connected to the housing 100. The scintillation crystal 400, the second through hole 331, the lens group 320, the cover window 200, the first through hole 120 and the camera 500 are arranged in sequence along the light transmission direction. The scintillation crystal 400 is used to receive EUV light and convert the EUV light into fluorescence (i.e., fluorescence in the visible light band) detectable by the camera 500. The fluorescence passes through the lens group 320, the cover window 200 and the first through hole 120 in sequence and is received by the camera 500. The lens group 320 is used to amplify and image the light spot on the scintillation crystal 400. The camera 500 is used to capture an image of the light spot on the scintillation crystal 400.

[0027] In some embodiments, the distance between the lens group 320 and the camera 500 and the distance between the lens group 320 and the scintillation crystal 400 are set to be adjustable, and the focusing of the lens group 320 can be achieved by adjusting the above two distances, so that the object-side focal plane of the lens group 320 coincides with the upper surface of the scintillation crystal 400, and the image-side focal plane of the lens group 320 coincides with the image sensor of the camera 500. Specifically, the lens group 320 can be detachably connected to the first bracket 310 and the second bracket 330 respectively, and the distance between the lens group 320 and the camera 500 can be adjusted by adjusting the relative position of the lens group 320 and the first bracket 310, and the distance between the lens group 320 and the scintillation crystal 400 can be adjusted by adjusting the relative position between the second bracket 330 and the lens group 320.

[0028] In some embodiments, lens group 320 is an achromatic lens group to minimize chromatic aberration and spherical aberration.

[0029] In some embodiments, the top of the camera 500 (the side where the image sensor is located) is fixedly connected to the housing 100, and the bottom of the camera 500 (the side where the chip is located) and the inner wall (i.e., the bottom plate) of the housing 100 are filled with a thermal pad 600, which is used to conduct the heat of the camera 500 to the housing 100 through the thermal pad 600, and then dissipate it outward from the housing 100, thereby improving the heat dissipation efficiency. Exemplarily, the thermal pad 600 can be a silicone pad with a thickness of 3mm, a thermal conductivity of 13W / (mk), and a temperature range of -40~+200℃. The thermal pad 600 is insulating, compression-resistant, and sticky. The thermal pad 600 can be multiple pieces and stacked between the camera 500 and the housing 100 to form a certain extrusion to increase the structural stability. Within the scope allowed by space, the bottom plate of the housing 100 can be designed to be larger, thereby increasing the heat radiation area and improving the heat dissipation efficiency.

[0030] In some embodiments, a temperature sensor 700 may be provided at the bottom of the camera 500 to monitor the operating temperature of the camera 500. The temperature sensor 700 may be disposed between the camera 500 and the thermal pad 600.

[0031] In some embodiments, the scintillation crystal 400 may be Ce:YAG, i.e., cerium-doped yttrium aluminum garnet. The size of the scintillation crystal 400 may be selected as required, for example, a scintillation crystal with a thickness of 300um and a diameter of 15mm may be selected. The scintillation crystal 400 may be attached to the upper surface of the second bracket 330 by silver glue.

[0032] A mark may be pre-engraved on the upper surface of the scintillation crystal 400. For example, a laser may be used to engrave a line with a width of 50 um at a distance of 2.5 mm from the center point of the scintillation crystal 400. The mark is used to adjust the focal length of the lens group 320. Specifically, when adjusting the distance between the lens group 320, the scintillation crystal 400 and the camera 500, the clarity of the mark on the upper surface of the scintillation crystal 400 captured by the camera 500 may be observed at the same time. When the image of the mark is clear in the field of view of the camera 500 and the width is the magnification of the lens group 320*50 um, it indicates that the adjustment is in place, and the lens group 320 may be fixed to the first bracket 310 and the second bracket 330.

[0033] The lens group 320 may be a 2x magnification lens group with an effective aperture of 9.5 mm and an applicable wavelength range of 400-700 nm.

[0034] In some embodiments, the cover window 200 can be made of Al2O3 sapphire. Sapphire is second only to diamond in hardness in nature, with a Mohs hardness of 9 and a melting point of 2050°C. It will not release gas or undergo thermal expansion at high temperatures and can remain stable under vacuum conditions, making it an ideal observation window material for vacuum devices. The cover window 200 can be circular, with a diameter of 25 mm and a thickness of 3 mm, and is polished on both sides. After EUV light excitation, the main emission peak of the fluorescence emitted by the scintillation crystal 400 is about 550 nm, and the light transmittance of sapphire to this wavelength is greater than 80%.

[0035] In some embodiments, the camera 500 is a board-level CMOS camera, model BFS-U3-32S4-BD2, with a pixel size of 3.45um and a pixel number of 2048x1536. Combined with the lens group 320, the field of view of the camera 500 is 3.5mm×2.6mm, and the theoretical spatial resolution is about 1.73um. The bottom of the camera 500 is the side where the main control chip is located. The main control chip is the main heating device of the camera 500, and the operating temperature range is 0~50℃.

[0036] In some embodiments, a switching circuit board 800 is further provided in the inner cavity 110. Figure 4As shown, the adapter circuit board 800 includes a wire-to-board connector 810 and a DB15 connector 820. The wire-to-board connector 810 is electrically connected to the camera 500 through a first wire 830, and is electrically connected to the temperature sensor 700 through a second wire 840. The housing 100 is also provided with a DB15 interface 130, and the DB15 connector 820 is plug-connected with the DB15 interface. The adapter circuit board 800 is used to convert the signal of the wire-to-board connector 810 into a standard signal of the DB15 connector 820, and then lead it out of the inner cavity 110 through the DB15 interface 130 on the housing 100. The DB15 interface 130 can be connected to a host computer (not shown in the figure) outside the inner cavity 110, so as to control the camera 500 and process its image data through the host computer.

[0037] In some embodiments, a sealing ring 210 may be provided between the cover window 200 and the outer shell 100 for sealing; the outer shell 100 may be composed of a plurality of detachable parts connected to each other, and the connecting parts between the detachable parts may also be sealed, so that the inner cavity 110 forms a closed cavity.

[0038] like Figure 5 As shown, the pupil detection device of the embodiment of the present invention is applied to an EUV mask defect detection system to detect the pupil of the EUV mask defect detection system. The EUV mask defect detection system includes a galvanometer 910, a reflector 920, an ellipsoidal reflector 930, a zone plate 940 and a CCD (charge coupled device) detector 950. EUV light is incident on the galvanometer 910. The galvanometer 910 is used to perform angle scanning so that the incident EUV light is emitted at different angles. The reflector 920 and the ellipsoidal reflector 930 collect the emitted light beam and focus it on one of the focal points of the ellipsoidal reflector 930. The horizontal plane where the focal point is located is the mask surface 960. When performing defect detection, a mask (not shown in the figure) is placed on the mask surface 960, and EUV light is irradiated on the mask and reflected by the mask. The zone plate 940 is used to amplify the reflected light of the mask and project it onto the CCD detector 950 for imaging. The image detected by the CCD detector 950 can be used to determine whether the mask has defects. Before scanning the mask, the illumination mode of the EUV mask defect detection system needs to be detected by a pupil detection device. The distribution of the direct light under the mask surface 960 and the reflected light reflected from the mask is equivalent, so the pupil detection device can be used to image the direct light under the mask surface 960, thereby indirectly obtaining the distribution information of the reflected light on the wave zone plate 940.

[0039] The EUV mask defect detection system also includes a three-dimensional motion console 970. The pupil detection device is placed on the three-dimensional motion console 970 and is located directly below the mask surface 960. The three-dimensional motion console 970 can move the pupil detection device along the X direction (the X direction is a direction perpendicular to the YZ plane), along the Y direction, and along the Z direction, wherein the X-direction movement is formed to be 100 mm, the Y-direction movement stroke is 100 mm, and the Z-direction movement stroke is 40 mm.

[0040] The EUV mask defect detection system also includes a vacuum chamber 980, in which a galvanometer 910, a reflector 920, an ellipsoid reflector 930, a zone plate 940, a CCD detector 950, a three-dimensional motion control console 970, and a pupil detection device are all located. A vacuum cable can be used to connect the DB15 interface 130 of the pupil detection device and the DB15 interface on the vacuum chamber 980, and then the temperature controller 991, the USB3.0 interface 992, and the galvanometer control device are connected through the DB15 interface on the vacuum chamber 980. The temperature controller 991 is connected to the temperature sensor 700 to monitor the working temperature of the camera 500 and prevent the camera 500 from being damaged due to long-term overheating; the USB3.0 interface 992 is used to connect to the data line of the camera 500, and is used to transmit the image data of the camera 500 to the host computer 994 through USB3.0; the galvanometer controller 993 is used to connect to the external trigger signal line of the camera 500 to input an external trigger acquisition signal to the camera 500, so as to realize the synchronous acquisition of pupil detection and galvanometer scanning.

[0041] When performing pupil detection, the three-dimensional motion console 970 can be used to first move the pupil detection device into the optical path, and the pupil image observed by the camera 500 is located at the center of the field of view. When the three-dimensional motion console 970 moves the pupil detection device along the Z direction, the pattern of the pupil image detected by the pupil detection device is related to the distance between the pupil detection device and the mask surface 960. When the upper surface of the scintillation crystal 400 coincides with the mask surface 960, the pupil image I0 is a constant light spot as the galvanometer 910 scans; when the pupil detection device is a certain distance away from the mask surface 960, the light beam is no longer focused and presents a pattern consistent with the scanning trajectory of the galvanometer 910, as shown in the pupil image I1; as the pupil detection device is further away from the mask surface 960, the larger the pupil image, the greater the distance between adjacent light beams, and the clearer the trajectory of the scanning light beam, as shown in the pupil image I2.

[0042] The relationship between the pupil size, the angle range of the light beam incident at the mask surface 960, and the defocus distance is as follows:

[0043]

[0044] Wherein, h is the distance between the upper surface of the scintillation crystal 400 and the mask surface 960 in the Z direction. When h is equal to the focal length of the zone plate 940, the pupil detected by the pupil detection device is equal in size to the pupil at the zone plate 940. is the minimum incident angle in the current lighting mode, is the maximum incident angle, and S is the maximum size of the pupil at the current distance h. When the size of S exceeds the field of view of the pupil detection device, the pupil detection device can be horizontally moved by the three-dimensional motion console 970 to collect images of multiple regions, and then the images of each region are spliced ​​to obtain a complete pupil image. Specifically, when the size of the pupil image is larger than the field of view of the pupil detection device, the image observed by the pupil detection device is only a part of the complete pupil image, and the images collected by the pupil detection device at different positions are different parts of the complete pupil image, so they are spliced ​​to obtain a complete pupil image.

[0045] The pupil detection device of the embodiment of the present invention can also detect the incident angle of the light beam at the mask surface 960. The measurement principle is as follows: Figure 6 As shown, two pupil images are first collected, one is a pupil image at a defocus distance (i.e., the distance between the scintillation crystal 400 and the mask surface 960) of 0 (which can be called a mask surface pupil image), and the other is a pupil image at a defocus distance of h (which can be called a defocus surface pupil image). In order to distinguish the positions of two adjacent light beams, h can satisfy the following relationship:

[0046]

[0047] in, is the minimum incident angle of the light beam at the mask surface, is the minimum angle between two adjacent light beams in the current scanning mode, d is the diameter of the EUV spot, and M is the magnification of the lens group 320. For example, the diameter of the EUV spot is 30 um, M is 2, =2mrad, then h is at least 7.5mm.

[0048] Extract the center position of each spot in the two pupil images, record the center coordinates of the spot of the mask surface pupil image as (x0, y0), and the center coordinates of the spot of the defocus surface pupil image as (x i , y i )(i is a positive integer, indicating the serial number of the light spot, i∈[0, N-1], N is the number of light spots in the pupil image of the defocused plane), s is the horizontal distance between the two light spots, and the incident angle of each light beam on the mask surface is The calculation formula is as follows:

[0049]

[0050] The method for collecting pupil images of the pupil detection device according to the embodiment of the present invention comprises the following steps:

[0051] S1: Provide the pupil detection device in the above embodiment and install it on the three-dimensional motion console 970 of the EUV mask defect detection system;

[0052] S2: Setting the galvanometer 910 to deflect only one angle, so that the EUV light is deflected to the center angle in the pre-scan mode;

[0053] S3: Move the pupil detection device into the optical path through the three-dimensional motion console 970 so that the upper surface of the scintillation crystal 400 overlaps with the mask surface 960;

[0054] S4: Open the camera acquisition software, slowly move the pupil detection device hmm along the Z axis, and continuously move the pupil detection device horizontally during the movement process so that the image of the light spot is always located in the center of the image;

[0055] S5: setting the exposure time of image acquisition according to the scanning rate and the number of scanning points of the galvanometer 910;

[0056] Exposure time = k × number of scanning points / scanning rate.

[0057] k is an integer. If the image signal is weak, the exposure time can be increased by integer multiples.

[0058] S6: Setting the scanning trajectory of the galvanometer 910 and driving the galvanometer 910 to scan;

[0059] S7: Whenever the galvanometer 910 starts to scan the first angle of the preset pattern, the galvanometer controller 993 outputs a pulse signal, sets the trigger mode of the camera 500 to the external trigger mode, and collects and saves the image;

[0060] S8: Stop the galvanometer scanning and set the galvanometer polarization angle to the center angle;

[0061] S9: Slowly move the three-dimensional motion console along the Z axis by a total of h mm to make the upper surface of the scintillation crystal 400 coincide with the mask surface 960, adjust the exposure time to a suitable value to avoid overexposure of the image, set the trigger mode of the camera 500 to the internal trigger mode, and collect and save the image.

[0062] The pupil detection device of the embodiment of the present invention can work in a vacuum chamber with a vacuum degree better than 1e-7torr, and detect the synthetic illumination pattern in the EUV mask defect detection system. It has a compact design and does not require structural modification of the EUV mask defect detection device during installation and use. The operating temperature of the camera 500 is monitored by the temperature sensor 700 to avoid damage due to excessive temperature, thereby improving the reliability of the pupil detection device.

[0063] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A pupil detection device, characterized in that: The invention comprises an outer shell, wherein the outer shell defines an inner cavity, the outer shell is provided with a first through hole, and a covering window, a first bracket, a lens group, a second bracket and a scintillation crystal are arranged outside the inner cavity, the first bracket is fixed to the outer shell, the lens group is fixed to the first bracket, the second bracket is fixed to the lens group, a second through hole is arranged on the second bracket, and the scintillation crystal is fixed to the second bracket and covers the second through hole; the covering window is fixed to the outer shell and / or the first bracket and covers the first through hole, a camera is arranged in the inner cavity, and the camera is fixedly connected to the outer shell; the scintillation crystal, the second through hole, the lens group, the covering window, the first through hole and the camera are arranged in sequence along the light transmission direction, the scintillation crystal is used to convert EUV light into fluorescence, the lens group is used to amplify and image the fluorescence on the scintillation crystal, and the camera is used to capture an image of the fluorescence on the scintillation crystal.

2. The pupil detection device according to claim 1, characterized in that The lens group is detachably connected to the first bracket and the second bracket respectively, so as to adjust the distance between the lens group and the camera by adjusting the relative position between the lens group and the first bracket, and to adjust the distance between the lens group and the scintillation crystal by adjusting the relative position between the lens group and the second bracket.

3. The pupil detection device according to claim 1, characterized in that The lens group is an achromatic lens group.

4. The pupil detection device according to claim 1, characterized in that The top of the camera is fixedly connected to the housing, and a thermal pad is filled between the bottom of the camera and the inner wall of the housing.

5. The pupil detection device according to claim 1, characterized in that: A temperature sensor is provided at the bottom of the camera.

6. The pupil detection device according to claim 5, characterized in that A transfer circuit board is also provided in the inner cavity, and the transfer circuit board includes a wire-to-board connector and a DB15 connector. The wire-to-board connector is electrically connected to the camera through a first wire, and is electrically connected to the temperature sensor through a second wire. A DB15 interface is provided on the outer shell, and the DB15 connector is plug-connected to the DB15 interface.

7. The pupil detection device according to claim 1, characterized in that: The material of the scintillation crystal is Ce:YAG, and the material of the cover window is sapphire.

8. The pupil detection device according to claim 1, characterized in that: The upper surface of the scintillation crystal is engraved with markings.

9. The pupil detection device according to claim 1, characterized in that: A sealing ring is arranged between the cover window and the shell.

10. The pupil detection device according to claim 1, characterized in that: Applied to an EUV mask defect detection system, the EUV mask defect detection system includes a galvanometer, a reflector, an ellipsoid reflector, a three-dimensional motion control console and a vacuum chamber, the galvanometer, the reflector, the ellipsoid reflector and the three-dimensional motion control console are all located in the vacuum chamber, the galvanometer is used to make EUV light emit at different angles, the reflector is used to reflect the EUV light emitted from the galvanometer onto the ellipsoid reflector, the ellipsoid reflector is used to focus the EUV light onto one of the focal points of the ellipsoid reflector, and the horizontal plane where the focus is located is used as the mask surface; the pupil detection device is arranged on the three-dimensional motion control console and is located directly below the mask surface.

Images