Image quality detection nanodot mechanism for bright field microscopic imaging

Abstract

The invention provides an image quality detection nano-dot mechanism for bright field microscopic imaging, and belongs to the field of imaging image quality detection.The image quality detection nano-dot mechanism comprises a nano-structure scatterer and a substrate, high-reflectivity coating films are arranged on the upper surface and the lower surface of the substrate, an imaging area without the high-reflectivity coating film is arranged in the middle of the upper surface of the substrate, and the high-reflectivity coating films are arranged in the imaging area. And the nano-structure scatterer is arranged in the imaging area. According to the application, the substrate with the imaging area is arranged in the area of the image quality detection nano-dot mechanism, so that the image quality detection nano-dot mechanism meets a strong scattering effect and a high bright field image signal-to-noise ratio under the working wavelength of the bright field microscopic imaging system, and is convenient to popularize and apply in the field of online image quality detection of the bright field microscopic imaging system.

Description

Technical Field

[0001] The invention belongs to the field of imaging image quality detection, and in particular relates to an image quality detection nano-dot mechanism for bright field microscopic imaging. Background Art

[0002] In the field of image quality detection of microscopic imaging systems, especially in bright-field microscopic imaging systems with large numerical aperture and wide field of view objectives, online image quality detection faces problems such as high difficulty in integrating detection tools, weak detection signals, and difficulty in filtering out interfering stray light. These problems lead to low accuracy and repeatability of image quality detection results, and the difficulty of online integrated high-throughput detection, which seriously limits the industrialization and integration of high-performance bright-field microscopic imaging systems.

[0003] In traditional brightfield microscopy systems, the signal-to-noise ratio (SNR) of these nanodot structures is low. This is primarily due to the strong light reflected from the nanostructures' substrates, which acts as an interference signal and reduces the SNR of the scattered light imaging. Therefore, improving the SNR of nanostructure imaging is crucial for online point spread function (PSF) measurements in brightfield microscopy systems. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the present invention aims to provide a nano-dot mechanism for image quality detection for bright field microscopy imaging, which can solve the above-mentioned problems.

[0005] Design principle: In a bright-field microscopy imaging system, a point radiation source on the object surface can be realized by illuminating and exciting the nanostructure. Its scattering field can be approximated as a point source radiation field, and it also has the significant advantage of being able to be measured online in real time. Secondly, the upper surface of the substrate of the nanostructure is coated (highly reflective film) in the non-imaging area, and the imaging area of ​​a specific size around the nanostructure is not coated, while the lower surface of the substrate is coated (highly reflective film) to reduce the interference signal on the imaging of the nanostructure.

[0006] A nano-dot mechanism for image quality detection for microscopic imaging includes a nano-structured scatterer and a substrate. High-reflective coatings are provided on the upper and lower surfaces of the substrate. An imaging area without high-reflective coating is provided in the middle of the upper surface of the substrate. The nano-structured scatterer is provided in the imaging area.

[0007] Furthermore, under bright field illumination with a specific polarization and a specific angle, the signal scattered light of non-nanostructure scatterers is filtered out by the nanodot structure and is not collected by the imaging system.

[0008] Furthermore, the nanostructured scatterer has an operating wavelength in the ultraviolet and / or deep ultraviolet band, and has a scattered light greater than NA0.9 in the yz plane and a scattered light greater than NA0.8 in the xz plane under X-polarized pupil illumination.

[0009] Compared with the existing technology, the beneficial effect of the present invention is that: by setting a substrate with an imaging area in the image quality detection nano-dot mechanism area, the image quality detection nano-dot mechanism can meet the strong scattering effect and high bright field image signal-to-noise ratio at the working wavelength of the bright field microscopy imaging system, which is convenient for promotion and application in the field of online image quality detection of bright field microscopy imaging systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Schematic diagram of the nano-dot mechanism for image quality detection according to the present invention; Figure 2 An example diagram of the layout of a nanostructured scatterer having a circular cross section in the imaging area of ​​the image quality detection nanodot mechanism; Figure 3 An example diagram of the layout of a nanostructured scatterer having a rectangular cross section in an imaging area of ​​a quality detection nanodot mechanism; Figure 4 Schematic diagram of arranging two imaging areas for a substrate; Figure 5 Schematic diagram of the optical path of the nano-dot mechanism for image quality detection; Figure 6 is the scattering far-field three-dimensional distribution diagram of the nanostructure scatterer; Figure 7 is the two-dimensional far-field distribution of the scattering of the nanostructured scatterer. DETAILED DESCRIPTION

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0012] A nano-dot image quality detection mechanism for bright field microscopy, see Figure 1-Figure 7 The image quality detection nanodot mechanism includes a nanostructured scatterer (nano-scatter) 11 and a substrate 12. High-reflective coatings 13 are applied to the upper and lower surfaces of substrate 12. An imaging region 14 is defined in the middle of the upper surface of substrate 12, without high-reflective coating 13. Nanostructured scatterer 11 is disposed in imaging region 14. The bright-field image of nanostructured scatterer 11 can serve as the point spread function of a bright-field microscopy imaging system.

[0013] The cross section of the nanostructured scatterer 11 is circular ( Figure 2 ),rectangle( Figure 3), star-shaped or regular polygonal, preferably circular, so as to form a disc-shaped structure that is easy to process.

[0014] The diameter of the circumscribed circle of the nanostructured scatterer 11 ranges from 100 nm to 180 nm. Currently used diameters for the circumscribed circle of the nanostructured scatterer 11 include 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, and 190 nm. Under ultraviolet / deep ultraviolet microscopy, diameters of 150 nm and 160 nm are ideal.

[0015] The working wavelength of the nanostructured scatterer 11 is the ultraviolet and / or deep ultraviolet band, see Figure 6 and Figure 7 , under X-polarized pupil illumination, it has scattered light greater than NA0.9 in the yz plane and scattered light greater than NA0.8 in the xz plane.

[0016] The substrate 12 is a transparent flat plate. In the example shown in the figure, the substrate 12 is a transparent glass plate.

[0017] The materials of the nanostructured scatterer 11 and the high-reflective coating 13 are chromium or other high-response (reflective) materials.

[0018] A plurality of nanostructured scatterers 11 are arranged in the imaging area 14 on the upper surface of the substrate 12, and the distances between the plurality of nanostructured scatterers 11 satisfy the near-field no-coupling condition. Multiple nanostructured scatterers 11 are arranged in a rectangular matrix ( Figure 2 and Figure 4 ), ring matrix arrangement ( Figure 3 ) or randomly arranged, and satisfy the near-field no-coupling condition.

[0019] The imaging area 14 is rectangular or circular. Figure 2 and Figure 4 In the example, it is a square. Figure 3 The nanostructured scatterers 11, which are circular in cross section and disk-shaped overall, are arranged in a rectangular matrix within a square imaging area 14. The width or diameter of the imaging area 14 is determined by the thickness of the substrate 12 and the lighting conditions.

[0020] The height of the nanostructured scatterer 11 is equal to the thickness of the high reflective coating 13 on the upper surface of the substrate 12. Of course, the height of the nanostructured scatterer 11 can also be higher than the thickness of the high reflective coating 13 on the upper surface of the substrate 12.

[0021] The thickness of the high reflective coating 13 on the lower surface of the substrate 12 is equal to or different from the thickness of the high reflective coating 13 on the upper surface.

[0022] In the illustrated example, the side length of the imaging area 14 is 900 μm, the height of the nanostructured scatterer 11 and the thickness of the high-reflective coating 13 on the upper surface of the substrate 12 are both 100 nm, the thickness of the high-reflective coating 13 on the lower surface of the substrate 12 is 200 nm, the center distance between adjacent nanostructured scatterers 11 is 20 μm, and the thickness of the substrate 12 is 775 μm.

[0023] For further information, see the attached Figure 4 Two imaging areas 14 are set on a substrate 12, and of course one, three, four or more imaging areas can also be set.

[0024] against Figure 5 For example, consider the incident angle ( b ) Near the Brewster angle (50~60 degrees), the incident polarization is P polarization.

[0025] For further information, see the attached Figure 5 , the imaging area 14 of the nanostructure in the entire lower and upper surfaces of the substrate 12 ( W ) are coated with high-reflective coating 13 (high-reflective film). Considering the incident angle ( b ), substrate 12, i.e., glass substrate thickness ( H ), the size of the imaging area 14 of the nanostructure ( W ), and satisfy the relationship W< 2 *H* tan c ,in c Depend on b According to the law of refraction, b When the temperature is 50~60 degrees, c The illumination light adopts P polarized light. b With the incident angle illumination, near the imaging area 14, the bright field microscopy system will only collect the scattered light of the nanostructured scatterer 11, and the P polarized light illuminating the substrate 12 will pass through the upper surface and be guided to the far end in the light guide cavity formed by the high reflective coating 13 on the upper and lower surfaces, as shown in FIG. Figure 5 The light path is shown by the black arrow.

[0026] The image quality detection nano-dot mechanism has been applied to online image quality detection of bright field microscopy imaging systems, and can be expected to be applied to online system image quality detection scenarios such as semiconductor bright field quantity detection and overlay alignment quantity detection systems.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A nano-dot image quality detection mechanism for bright field microscopy, characterized by: The image quality detection nano-dot mechanism comprises a nano-structured scatterer (11) and a substrate (12); a high-reflective coating (13) is provided on the upper and lower surfaces of the substrate (12); an imaging area (14) without the high-reflective coating (13) is provided in the middle of the upper surface of the substrate (12); and the nano-structured scatterer (11) is provided in the imaging area (14).

2. The image quality detection nano-dot mechanism according to claim 1, characterized in that: The cross section of the nanostructured scatterer (11) is circular, rectangular, star-shaped or regular polygonal, and the diameter of the circumscribed circle of the nanostructured scatterer (11) ranges from 100 nm to 180 nm.

3. The image quality detection nano-dot mechanism according to claim 1, characterized in that: The working wavelength of the nanostructured scatterer (11) is the ultraviolet and / or deep ultraviolet band, and under the illumination of the X-polarized pupil, the scattering light has a scattering light greater than NA0.9 in the yz plane and a scattering light greater than NA0.8 in the xz plane.

4. The image quality detection nano-dot mechanism according to claim 1, characterized in that: The substrate (12) is a transparent flat plate.

5. The image quality detection nano-dot mechanism according to claim 1, characterized in that: The nanostructured scatterer (11) and the high-reflective coating (13) are made of chromium.

6. The image quality detection nano-dot mechanism according to claim 1, characterized in that: A plurality of nanostructured scatterers (11) are arranged in an imaging area (14) on the upper surface of a substrate (12), and the distances between the plurality of nanostructured scatterers (11) satisfy a near-field no-coupling condition.

7. The image quality detection nano-dot mechanism according to claim 1, characterized in that: The imaging area (14) is rectangular or circular.

8. The image quality detection nano-dot mechanism according to claim 1, characterized in that: The width or diameter of the imaging area (14) is determined by the thickness of the substrate (12) and the lighting conditions.

9. The image quality detection nano-dot mechanism according to claim 1, characterized in that: The height of the nanostructured scatterer (11) is equal to the thickness of the high-reflective coating (13) on the upper surface of the substrate (12).

10. The image quality detection nano-dot mechanism according to claim 1, characterized in that: The bright field image of the nanostructured scatterer (11) was used as the point spread function of the bright field microscopy system.

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