Illuminating device, defect detection system, photolithography machine, and defect detection method

Abstract

The present invention provides an illumination device, a defect detection system, a photolithography machine, and a defect detection method. The illumination unit is used to provide linear illumination. The light adjustment unit is used to adjust the divergence angle of the illumination to a preset value. The light splitting unit is used to split the illumination after the light adjustment unit into at least two beams of sub-illumination. The at least two beams of sub-illumination are staggered and the light spots formed by the superposition of light intensities include light spots with flat-top Gaussian distribution. Therefore, the present invention increases the divergence angle of the illumination to a preset value through the light adjustment unit to achieve telecentric illumination in a limited space and improve the accuracy of defect detection. The light spot formed by the light splitting unit ensures the uniformity of partial light intensity in a certain direction, avoids uneven and unstable light intensity caused by internal movement and external vibration, and causes an impact on defect detection, thereby ensuring the high accuracy of the defect detection system and helping to improve product yield.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular to an illumination device, a defect detection system, a photolithography machine, and a defect detection method. Background Art

[0002] In the manufacturing process of semiconductor integrated circuits or flat panel displays, contamination control is a crucial step to improve product yield. The glass and film surfaces of the reticle, which serves as the pattern template, are susceptible to contamination and damage during the clamping, transportation, storage, and exposure processes, resulting in defects such as foreign particles, fingerprints, scratches, and pinholes. Without defect detection before exposure, the presence of these defects during the exposure process will directly affect the exposure performance of the lithography machine and the product yield. Therefore, defect detection is necessary before the reticle is exposed to determine whether it is suitable for direct exposure, thereby preventing the impact of reticle defects on the exposure.

[0003] Currently, reticle defect detection methods primarily utilize a defect detection system consisting of an illumination device and an imaging detection device. Specifically, the illumination device projects measurement light onto the reticle. This measurement light scatters at the reticle defect, and the resulting scattered light enters the corresponding imaging detection device. The imaging detection device detects the scattered light signal and processes the detection results to obtain information such as the equivalent size of the reticle defect. To ensure defect detection accuracy, the illumination device must provide telecentric illumination, and the higher the telecentricity, the more accurate the detection.

[0004] However, the detection accuracy of the current defect detection system, which mainly consists of lighting devices and imaging detection devices, cannot be further improved. The main reasons include:

[0005] 1. The defect detection system is generally integrated into the lithography machine. Due to the limitation of the mechanical space inside the lithography machine, the existing defect detection system is required to be small enough to avoid occupying too much mechanical space inside the lithography machine, resulting in limited defect detection accuracy.

[0006] 2. Because both the top and bottom surfaces of the reticle need to be inspected for defects, the reticle must be placed on a reticle fork (a reticle carrier) during the actual inspection process. However, because the reticle fork is easily affected by the internal motion mechanism of the lithography equipment and external vibrations, and the light intensity distribution gradient of the measurement light provided by the illumination device is large, the defect detection system's defect detection results (such as particle grayscale) are poorly repeatable, seriously affecting defect detection accuracy.

[0007] Therefore, a new lighting device, defect detection system, photolithography machine and defect detection method are needed to improve the defect detection accuracy. Summary of the Invention

[0008] The object of the present invention is to provide an illumination device, a defect detection system, a photolithography machine and a defect detection method to solve the problem of low defect detection accuracy.

[0009] In order to solve the above technical problems, the present invention provides a lighting device, which includes: a lighting unit, a light adjustment unit and a light splitting unit arranged in sequence along a light path;

[0010] The illumination unit is used to provide linear illumination and transmit it to the light adjustment unit;

[0011] The light adjustment unit is used to adjust the divergence angle of the illumination to a preset value, and the adjusted illumination is telecentric illumination;

[0012] The light splitting unit is used to split the light after passing through the light adjustment unit into at least two beams of sub-light; the at least two beams of sub-light are staggered and the light spots formed by the superposition of light intensities include light spots with flat-top Gaussian distribution.

[0013] Optionally, in the lighting device, the light spot formed by the staggered distribution of the at least two beams of light and the superposition of light intensities has uniform light intensity in the length direction, and part of the light intensity in the width direction presents a flat-top Gaussian distribution; wherein the length direction and the width direction are perpendicular to each other.

[0014] Optionally, in the lighting device, the light splitting unit includes a wedge-shaped substrate, and the light passes through the wedge-shaped substrate after passing through the light adjustment unit to form the at least two sub-beams of light.

[0015] Optionally, in the lighting device, the light splitting unit further includes flat glass.

[0016] Optionally, in the lighting device, the flat glass and the wedge-shaped substrate are spliced together; part of the light is transmitted through the flat glass, and part of the light is transmitted through the wedge-shaped substrate.

[0017] Optionally, in the lighting device, the flat glass and the wedge-shaped substrate are stacked on each other; part of the light is transmitted through the flat glass, and part of the light is transmitted through the flat glass and the wedge-shaped substrate in sequence.

[0018] Optionally, in the lighting device, the preset value range of the divergence angle is: greater than 20 degrees and less than 90 degrees.

[0019] Optionally, in the lighting device, the light adjustment unit includes a cylindrical microlens array, a Powell prism and / or a diffuser.

[0020] Optionally, in the lighting device, the lighting device further comprises: a beam expander and a collimator lens group; wherein,

[0021] The beam expander is used to expand the light so that the diameter of the light is enlarged and the light can be propagated in parallel to the light adjustment unit;

[0022] The collimating lens group is used to maintain the collimation of the at least two staggered sub-beams of light outputted by the light splitting unit.

[0023] Based on the same inventive concept, the present invention also provides a defect detection system, comprising the lighting device and the imaging detection device; wherein,

[0024] The lighting device is used to provide a light spot as measurement light, and project the measurement light onto the object to be measured having a defect, so that the measurement light is scattered at the defect and generates scattered light; wherein the light spot provided by the lighting device includes a light spot with a flat-top Gaussian distribution;

[0025] The imaging detection device is used to receive and detect the scattered light, and process the detected information to obtain the information of the defect.

[0026] Optionally, in the defect detection system, the defect information includes the equivalent size and position coordinates of the defect.

[0027] Optionally, in the defect detection system, the defect detection system further includes a focal plane measurement device, a first motion stage and a second motion stage; wherein,

[0028] The focal plane measurement device is used to measure the position of the object to be measured relative to the imaging detection device;

[0029] The first motion stage is used to adjust the distance between the object to be measured and the imaging detection device in a first direction;

[0030] The second motion platform is used to carry the object to be measured and drive the object to be measured to move along the second direction, so that the measuring light can scan the entire surface of the object to be measured.

[0031] Optionally, in the defect detection system, the first direction and the second direction are perpendicular to each other.

[0032] Optionally, in the defect detection system, the imaging detection device includes an imaging detection lens group and a detector; the imaging detection lens group is used to converge the scattered light and transmit it to the detector; the detector is used to detect the scattered light and process the detected information to obtain the defect information.

[0033] Based on the same inventive concept, the present invention also provides a lithography machine, which includes the defect detection system.

[0034] Based on the same inventive concept, the present invention also provides a defect detection method, comprising:

[0035] The illumination device provides a light spot for measuring light, wherein the light spot includes a light spot with a flat-top Gaussian distribution;

[0036] The measuring light is projected onto the object to be measured. If the measuring light is projected onto a defect on the object to be measured, scattering occurs and scattered light is generated. The scattered light is transmitted to the imaging detection device.

[0037] The imaging detection device detects the scattered light and obtains defect information.

[0038] Optionally, in the defect detection method, the defect information includes the equivalent size and position coordinates of the defect

[0039] In summary, the present invention provides an illumination device, a defect detection system, a photolithography machine, and a defect detection method. The illumination device includes: an illumination unit, a light adjustment unit, and a light splitting unit sequentially arranged along the optical path. The illumination unit is used to provide linear illumination and propagate to the light adjustment unit. The light adjustment unit is used to adjust the divergence angle of the illumination to a preset value, and the adjusted illumination is telecentric illumination. The light splitting unit is used to split the illumination after passing through the light adjustment unit into at least two beams of sub-illumination. The at least two beams of sub-illumination are staggered and the light spots formed by the superposition of light intensities include light spots with flat-top Gaussian distribution. Therefore, the present invention increases the divergence angle of the illumination to a preset value through the light adjustment unit, thereby realizing telecentric illumination in a limited space to improve the accuracy of defect detection. Moreover, the light spot generated after adjustment by the light adjustment unit includes a light spot with a flat-top Gaussian distribution, so as to ensure the uniformity of partial light intensity in a certain direction, avoid internal movement and external vibration causing uneven and unstable light intensity, which may affect defect detection, thereby ensuring the high accuracy of the defect detection system and helping to improve product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a schematic structural diagram of a defect detection system according to an embodiment of the present invention;

[0041] Figure 2 is a schematic structural diagram of a lighting device according to an embodiment of the present invention;

[0042] Figure 3 2 is a schematic structural diagram of a fork according to an embodiment of the present invention;

[0043] Figure 4 1 is a schematic diagram of the vibration of the fork according to an embodiment of the present invention;

[0044] Figure 5 is a simulation diagram of repeatability and vibration frequency of an embodiment of the present invention;

[0045] Figure 6 is a structural diagram of a light splitting unit according to an embodiment of the present invention;

[0046] Figure 7 is a structural diagram of a light splitting unit according to an embodiment of the present invention;

[0047] Figure 8 is a schematic diagram of sub-lights projected onto the same image plane according to an embodiment of the present invention;

[0048] Figure 9 2 is a schematic diagram showing the relationship between the light intensity and the spot position of a flattened Gaussian beam according to an embodiment of the present invention;

[0049] Figure 10 is a Y-direction cross-sectional view of the combination of the light adjustment unit and the light splitting unit according to an embodiment of the present invention;

[0050] Figure 11 is a cross-sectional view in the X direction of the combination of the light adjustment unit and the light splitting unit according to an embodiment of the present invention;

[0051] Figure 12 2 is a schematic diagram showing the relationship between the intensity of the measurement light and the position of the light spot before defocusing according to an embodiment of the present invention;

[0052] Figure 13 Schematic diagram of the relationship between the intensity of the defocused measurement light and the position of the light spot according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to make the objects, advantages and features of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis required to be shown in each drawing is different, and sometimes different scales are used. It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third" and the like in the specification are only used to distinguish between the various components, elements, steps, etc. in the specification, and are not used to represent the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0054] To solve the above technical problems, this embodiment provides a defect detection system. Figure 1, the defect detection system includes the lighting device 10 and the imaging detection device 20. The lighting device 10 provides a light spot with uniform light intensity in the length direction and a partial light intensity in the width direction that is a flat-top Gaussian distribution, as the measuring light, and the measuring light is projected onto the object M to be tested. The length direction and the width direction are perpendicular to each other. Furthermore, in the defect detection system, the width direction is the scanning direction of detection. The measuring light will be scattered by the defects on the object M to be tested and generate scattered light, and the scattered light will be propagated to the imaging detection device 20, and the defect information will be obtained after detection by the imaging detection device 20. If the measuring light is projected onto the surface of the object M to be tested and there is no defect, the measuring light will be reflected by the object M to be tested and generate reflected light, and the reflected light will not enter the imaging detection device 20. That is, when there is no defect on the surface of the object M to be tested, the imaging detection device 20 cannot receive the light beam.

[0055] Furthermore, the imaging detection device 20 includes an imaging detection lens assembly 201 and a detector 202. The imaging detection lens assembly 201 is used to focus the scattered light and transmit it to the detector 202. The detector is a photodetector that detects the scattered light and performs photoelectric conversion on it to obtain the defect information. The defect information includes the equivalent size and location coordinates of the defect.

[0056] In addition, the defect detection system also includes a focal plane measurement device 30, a first motion stage 40, and a second motion stage 50. The focal plane measurement device 30 is used to measure the position of the object to be measured M relative to the imaging detection device 20. Typical measurement principles include but are not limited to multi-wavelength confocal measurement, triangulation measurement, etc. The first motion stage 40 is used to adjust the distance between the object to be measured M and the imaging detection device 20 in the first direction, that is, to adjust the vertical height (Y direction) of the object to be measured M according to the detection information of the focal plane measurement device 30 to ensure that the scattered light can enter the imaging detection device 20 and the reflected light does not enter the imaging detection device 20. The second motion stage 50 is used to carry the object to be measured M and drive the object to be measured M to move along the second direction (X direction) to enable the measurement light to scan the entire surface of the object to be measured M. The first direction (Y direction) and the second direction (X direction) are perpendicular to each other.

[0057] Based on the same inventive concept, this embodiment also provides a lithography machine, which includes the defect detection system.

[0058] The object M to be measured in this embodiment takes a mask as an example. At present, the length and width of commonly used masks are about 152mm, and the effective area is usually above 132mm*104mm. This requires that the linear spot generated by the lighting device 10 needs to be at least larger than 104mm, preferably larger than 125mm. In order to ensure the accuracy of defect detection, the measurement light generated by the lighting device 10 has the following characteristics: the deviation between the main rays of each field of view in the measurement light beam is less than 5 degrees, preferably less than 1 degree. That is, the lighting device 10 needs to provide telecentric illumination. Among them, the illumination field d of the telecentric illumination, the focal length f of the collimating lens group and the divergence angle θ of the measurement light satisfy the following relationship:

[0059] d=f*sin(θ)*2;

[0060] However, due to the extremely limited mechanical space inside the lithography machine, the defect detection system must be compact, meaning the focal length f of the collimating lens group must be as small as possible. Therefore, while ensuring telecentric illumination, the divergence angle θ of the measurement light must be increased to meet this requirement.

[0061] Therefore, the lighting device 10 provided in this embodiment can solve the above problems. Figure 2 , the lighting device 10 includes an illumination unit 101, a light adjustment unit 103 and a light splitting unit 104. The illumination unit 101 is used to provide linear illumination and transmit it to the light adjustment unit 103. Optionally, the illumination unit 101 includes a laser, and the laser provides a linear light spot. The light adjustment unit 103 is used to adjust the divergence angle of the illumination to a preset value. The light splitting unit 104 is used to split the illumination after passing through the light adjustment unit 103 into at least two beams of sub-illumination; the at least two beams of sub-illumination are staggered and the light intensities are superimposed on each other to form a light spot with a flat-top Gaussian distribution. Furthermore, on the same image plane 106, the at least two beams of sub-illumination are staggered and the light intensities are superimposed on each other to form a light spot with uniform light intensity in the length direction and a partial light intensity in the width direction with a flat-top Gaussian distribution. The longitudinal and width directions are perpendicular to each other, and the propagation directions of the at least two sub-beams of light are inclined at a certain angle to the plane containing the longitudinal and width directions. Furthermore, during defect detection, the width direction serves as the scanning direction to ensure uniform light intensity during scanning, reduce the impact of vibration on detection, and improve the stability of subsequent detection.

[0062] Furthermore, the positions of the light adjustment unit 103 and the light splitting unit 104 can be interchanged, that is, the light can pass through the light adjustment unit 103 and the light splitting unit 104 in sequence; or, the light can pass through the light splitting unit 104 and the light adjustment unit 103 in sequence.

[0063] The divergence angle of the light after passing through the light adjustment unit 103 can be adjusted to greater than 20 degrees, thereby enabling the focal length of the collimating lens assembly 105 to be controlled to be less than 150 mm, or even less than 125 mm. Therefore, the lighting device 10 provided in this embodiment can meet the requirement of reducing the space occupied by the defect detection system, and has better adaptability and scalability.

[0064] Furthermore, the light adjustment unit 103 includes but is not limited to a cylindrical micro-lens array, a Powell prism and / or a diffuser. The preset value range of the divergence angle is: greater than 20 degrees and less than 90 degrees, preferably 40 degrees, 50 degrees or 60 degrees.

[0065] In addition, since both the upper and lower surfaces of the mask need to be inspected for defects in actual inspection, it is necessary to Figure 3 The fork N shown is used to support the reticle. The fork N is typically circular in shape, easily matching the shape of the reticle. To support the reticle and meet inspection requirements, the fork N is limited in thickness and cannot be made thicker. This results in a low modal response of the fork N, making it susceptible to the equipment's internal motion mechanisms and external vibrations, which in turn can cause vibrations in the reticle, affecting inspection accuracy.

[0066] See also Figure 4 , Figure 4 When the mask is inspected in the defect inspection system, the mask fork N is affected by the internal motion mechanism and the externally introduced vibration, and vibration may occur.

[0067] Although the imaging detection device 20 in the defect detection system has adopted a detector integration method to homogenize the scattered light, the vibration causes the incident angle of the measurement light and the receiving angle of the imaging detection device 20 to deviate from the normal direction of the mask, which will amplify the impact of vibration on detection. The detector integration method cannot effectively solve this problem. Figure 5 , Figure 5 This is a simulation diagram of the effect of vibrations of different frequencies on the sensitivity of the repeatability of particle grayscale measurement in the defect detection system. Particle grayscale repeatability is used to characterize the repeatability of particle grayscale detection. The smaller the particle grayscale repeatability, the better the repeatability of particle size detection, and the higher the detection accuracy. During the simulation, the amplitude corresponding to each frequency vibration is 1 micron, the horizontal axis is the vibration frequency, and the vertical axis is the effect on the repeatability of particle grayscale. Among them, a repeatability of 0.02 corresponds to a grayscale change of 2%. Therefore, from Figure 5 As can be seen from the figure, the vibration of the fork N has a great influence on the repeatability of particle grayscale detection.

[0068] In the simulation test, through simulation analysis Figure 4Measured vibration data revealed that the vibration of the fork N significantly impacted the repeatability of particle measurement grayscale by 16.7%, demonstrating its significant impact on the repeatability of particle measurement grayscale in the defect detection device. Analysis revealed that the fundamental cause of this effect is the large gradient in the intensity distribution of the measuring light. This causes variations in the dwell time corresponding to different positions of the measuring light distribution during vibration, ultimately resulting in variations in signal repeatability. In other words, vertical vibration causes instantaneous variations in the speed of the fork N in the horizontal direction X. Due to the large gradient in the intensity distribution of the measuring light, the energy collected differs significantly between the following two scenarios: First, when the relative light intensity is highest, the fork N moves at its slowest speed; and when it is lowest. Second, when the relative light intensity is highest, the fork N moves at its fastest speed; and when it is lowest, the fork N moves at its slowest speed. In other words, the vibration of the fork N causes instantaneous variations in its horizontal direction X speed, resulting in fluctuations in scattered light. This affects the repeatability of particle measurement grayscale and reduces defect detection accuracy.

[0069] In this regard, the lighting device 10 provided in this example obtains the light spot through the light splitting unit 104 to reduce the gradient of the intensity distribution of the measurement light, thereby ensuring the balance of light intensity and reducing the impact of vibration on detection accuracy.

[0070] For details, please refer to Figure 6 The light splitting unit 104 includes the flat glass 1041 and the wedge-shaped substrate 1042. The flat glass 1041 and the wedge-shaped substrate 1042 are spliced together. Part of the light is transmitted through the flat glass 1041, and part of the light is transmitted through the wedge-shaped substrate 1042. Figure 6 The splicing method shown is top-to-bottom splicing. In addition to the splicing method shown in the figure, left-to-right splicing can also be used, so that part of the light passes through the flat glass 1041 and the remaining part of the light passes through the wedge-shaped substrate 102.

[0071] In addition to the above-mentioned configuration, the flat glass 1041 and the wedge-shaped substrate 1042 can also be stacked on top of each other. Figure 7 , part of the light is transmitted through the flat glass 1041, and part of the light is transmitted through the flat glass 1041 and the wedge-shaped substrate 1042 in sequence. Because the illumination unit provides a typical Gaussian beam, the light intensity weakens from the center of the field of view to both sides. Therefore, at least two sub-beams of light can be obtained through the action of the flat glass 1041 and the wedge-shaped substrate 1042, and each sub-beam of light is a Gaussian beam. Figure 8As shown, multiple sub-lights are irradiated on the same image plane 106, and are staggered along the width direction of the light splitting unit 104 and the light intensities are superimposed on each other, the light intensity peaks are staggered, and through the superposition effect, a Figure 9 The light spot shown has uniform light intensity in the length direction and a flat-top Gaussian distribution of light intensity in part of the width direction. This ensures that the light intensity gradient varies slightly, ensuring that the intensity of the measurement light projected onto the mask is balanced, thereby reducing the impact of vibration on detection.

[0072] The light splitting unit 104 can be made of a flat glass. Figure 6 and Figure 7 That is, the flat glass 1041 and the wedge-shaped substrate 1042 can be integrally formed.

[0073] In addition, the light splitting unit 104 may also include only the wedge-shaped substrate 1042. Figure 11-12 The cylindrical microlens array, the Powell prism and / or the diffuser in the light adjustment unit 103 are integrally formed with the wedge-shaped substrate 1042. After the light passes through the cylindrical microlens array and / or the Powell prism, it passes through the wedge-shaped substrate 1042 to form the at least two sub-beams of light, thereby forming Figure 9 The light intensity is uniform in the length direction, and part of the light intensity in the width direction is a flat-top Gaussian distributed light spot, so as to ensure that the light intensity is stable and uniform during the scanning process, reduce the impact of vibration on detection, and improve detection accuracy.

[0074] Furthermore, in addition to obtaining the light spot by setting the light splitting unit 104, the light spot can also be obtained by defocusing. Figure 12 and Figure 13 As can be seen from the comparison diagram of , the defocusing method may cause the light spot width to be too large, so it is preferred to set the light splitting unit 104 to obtain the light spot.

[0075] After the light splitting unit 104 is set, Figure 4 The simulation test based on the measured vibration data showed that the effect of the vibration of the plate fork N on the repeatability of the grayscale measurement of particles was reduced to 6.6%. It can be seen that the light splitting unit 104 greatly alleviated the effect of the vibration of the plate fork N on the repeatability of the grayscale measurement of particles in the defect detection device.

[0076] It has been verified that the addition of the light splitting unit 104 only affects the telecentric illumination by 0.1 degrees, which is virtually ineffective. Furthermore, interference does not occur within the light splitting unit 104, and has no effect on the formation of the light spot, including the flat-top Gaussian distribution. This is because the semiconductor laser used in actual products has a dominant wavelength of 640 nanometers and a bandwidth of 4 nanometers, resulting in a coherence length of 0.1 micron. Assuming that the added wedge-shaped substrate 1042 is N-BK7 with a thickness of 2 microns and a refractive index of 1.51, the optical path difference between the segmented and non-segmented portions of the illumination is (1.51-1)*2=1.02 microns, which is significantly greater than 0.1 micron, and therefore does not interfere. Therefore, the illumination device not only ensures telecentric illumination but also produces a relatively stable light spot for measurement.

[0077] For further information, please refer to Figure 2 The lighting device further includes a beam expander 102 and a collimator lens group 105. After passing through the beam expander 102, the light forms parallel propagation with an expanded diameter. The light then passes through the light adjustment unit 103 and the light splitting unit 104 in sequence to form at least two sub-beams of light. After each sub-beam of light passes through the collimator lens group 105, telecentric illumination is achieved and the light spot is formed.

[0078] Based on the same inventive concept, this embodiment also provides a defect detection method, see Figure 1 ,include:

[0079] Step 1: The lighting device 10 provides a light spot as measurement light; wherein the light spot includes a light spot with a flat-top Gaussian distribution.

[0080] Preferably, on the same image plane, the light spot has uniform light intensity along its length, and a portion of its light intensity along its width exhibits a flat-top Gaussian distribution. The length and width directions are perpendicular to each other, and the width direction is the scanning direction. That is, along the scanning direction, the light spot's light intensity exhibits a nearly flat-top Gaussian distribution, ensuring uniform and stable light intensity during the scanning process. Furthermore, under the action of the light adjustment unit 103, the light spot exhibits telecentric illumination.

[0081] Step 2: The measurement light is projected onto the object M. If the measurement light strikes a defect on the object M, it is scattered and generates scattered light, which then propagates to the imaging detection device 20. If the measurement light strikes the surface of the object M and there are no defects, the measurement light is reflected by the object M and generates reflected light, which does not enter the imaging detection device 20. In other words, when there are no defects on the surface of the object M, the imaging detection device 20 does not receive the light beam.

[0082] Step 3: The imaging detection device 20 detects the scattered light and obtains defect information. That is, the detector 202 obtains the equivalent size or position information of the defect through photoelectric conversion to avoid the defect's impact on exposure, thereby improving product yield.

[0083] In summary, the lighting device, defect detection system, photolithography machine, and defect detection method provided in this embodiment are as follows. The light adjustment unit 30 is used to increase the divergence angle of the light to a preset value, thereby achieving telecentric illumination in a limited space to improve the accuracy of defect detection. In addition, the light splitting unit 40 is used to form a light spot with uniform light intensity in the longitudinal direction and a flat-top Gaussian distribution of partial light intensity in the width direction, so as to avoid uneven and unstable light intensity caused by internal movement and external vibration, which may affect defect detection, thereby ensuring the high accuracy of the defect detection system and helping to improve product yield.

[0084] Furthermore, it should be recognized that although the present invention has been disclosed above with reference to preferred embodiments, the above embodiments are not intended to limit the present invention. Any person skilled in the art can utilize the above disclosed technical content to make many possible changes and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent variations, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent variations, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A lighting device, characterized in that: The lighting device comprises: a lighting unit, a light adjustment unit, a light splitting unit and a collimating lens group arranged in sequence along the light path; The illumination unit is used to provide linear illumination and transmit it to the light adjustment unit; The light adjustment unit is used to adjust the divergence angle of the light to a preset value to reduce the focal length of the collimating lens group; and the adjusted light is telecentric light; The light splitting unit is used to split the light after passing through the light adjustment unit into at least two beams of sub-light; the light spots formed by the at least two beams of sub-light being staggered and superimposed on each other include light spots with flat-top Gaussian distribution; The collimating lens group is used to maintain the collimation of the at least two staggered sub-beams of light output by the light splitting unit.

2. The lighting device according to claim 1, characterized in that On the same image plane, the light spot formed by the staggered distribution of the at least two beams of light and the superposition of light intensities has uniform light intensity in the length direction, and part of the light intensity in the width direction presents a flat-top Gaussian distribution; wherein the length direction and the width direction are perpendicular to each other.

3. The lighting device according to claim 1, wherein The light splitting unit includes a wedge-shaped substrate. After passing through the light adjustment unit, the light passes through the wedge-shaped substrate to form the at least two sub-beams of light.

4. The lighting device according to claim 3, characterized in that The light splitting unit further includes flat glass.

5. The lighting device according to claim 4, characterized in that The flat glass and the wedge-shaped substrate are spliced together; part of the light is transmitted through the flat glass, and part of the light is transmitted through the wedge-shaped substrate.

6. The lighting device according to claim 4, characterized in that The flat glass and the wedge-shaped substrate are stacked on each other; part of the light is transmitted through the flat glass, and part of the light is transmitted through the flat glass and the wedge-shaped substrate in sequence.

7. The lighting device according to claim 1, wherein The preset value range of the divergence angle is: greater than 20 degrees and less than 90 degrees.

8. The lighting device according to claim 1, wherein The light adjustment unit includes a cylindrical microlens array, a Powell prism and / or a diffusion sheet.

9. The lighting device according to claim 1, wherein: The lighting device further includes: a beam expander; wherein, The beam expander is used to expand the light so that the diameter of the light is enlarged and the light can be propagated in parallel to the light adjustment unit.

10. A defect detection system, characterized in that: The defect detection system comprises the lighting device and imaging detection device according to any one of claims 1 to 9; wherein, The lighting device is used to provide a light spot as measurement light, and project the measurement light onto the object to be measured having a defect, so that the measurement light is scattered at the defect and generates scattered light; wherein the light spot provided by the lighting device includes a light spot with a flat-top Gaussian distribution; The imaging detection device is used to receive and detect the scattered light, and process the detected information to obtain the information of the defect.

11. The defect detection system according to claim 10, characterized in that: The defect information includes the equivalent size and position coordinates of the defect.

12. The defect detection system according to claim 10, characterized in that: The defect detection system further includes a focal plane measurement device, a first motion stage and a second motion stage; wherein, The focal plane measurement device is used to measure the position of the object to be measured relative to the imaging detection device; The first motion stage is used to adjust the distance between the object to be measured and the imaging detection device in a first direction; The second motion platform is used to carry the object to be measured and drive the object to be measured to move along the second direction, so that the measuring light can scan the entire surface of the object to be measured.

13. The defect detection system according to claim 12, characterized in that: The first direction and the second direction are perpendicular to each other.

14. The defect detection system according to claim 10, wherein: The imaging detection device includes an imaging detection lens group and a detector; the imaging detection lens group is used to converge the scattered light and transmit it to the detector; the detector is used to detect the scattered light and process the detected information to obtain the defect information.

15. A photolithography machine, characterized in that: The lithography machine includes the defect detection system according to any one of claims 10-14.

16. A defect detection method, characterized in that: Using the defect detection system according to any one of claims 10 to 14, the defect detection method comprises: The illumination device provides a light spot for measuring light, wherein the light spot includes a light spot with a flat-top Gaussian distribution; The measuring light is projected onto the object to be measured. If the measuring light is projected onto a defect on the object to be measured, scattering occurs and scattered light is generated. The scattered light is transmitted to the imaging detection device. The imaging detection device detects the scattered light and obtains defect information.

17. The defect detection method according to claim 16, characterized in that: The defect information includes the equivalent size and position coordinates of the defect.

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