Optical module and semiconductor wafer defect detection equipment with same

Abstract

The invention discloses an optical module and semiconductor wafer defect detection equipment with the same, and relates to the technical field of wafer detection. The optical module comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially distributed in the direction from the object side to the image side, the first lens and the second lens are glued, the third lens and the fourth lens are glued, and an aperture diaphragm is arranged in the object side direction of the first lens; the first lens is a biconvex lens with positive focal power, the second lens is a meniscus lens with negative focal power, the third lens is a biconvex lens with positive focal power, the fourth lens is a biconcave lens with negative focal power, and the fifth lens is a meniscus lens with negative focal power. The optical module provided by the invention can have a large field of view of 40mm, is convenient for subsequent observation and detection, and is good in image quality.

Description

Technical Field

[0001] This application relates to the field of wafer inspection technology, and in particular to an optical module and a semiconductor wafer defect inspection device having the same. Background Technology

[0002] Patternless wafer defect inspection is a quality control process for bare silicon wafers or wafers without surface circuit patterns. Its core objective is to identify surface and subsurface defects that may affect the yield of subsequent processes before the wafer is put into production.

[0003] As a crucial upstream step in semiconductor manufacturing, patternless wafer defect detection technology directly determines chip yield and reliability. However, the full field of view of the 200mm tube lens in the relevant detection equipment is between 5mm and 20mm. This structure cannot meet the requirements for global observation of large samples. At this time, it is necessary to use stitching algorithms to capture complete images, which is cumbersome. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the related technologies, it is desirable to provide an optical module and a semiconductor wafer defect detection device having the same, which has a large field of view, is convenient for detection, and at the same time ensures good image quality.

[0005] In a first aspect, this application provides an optical module, the optical module including a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged sequentially along the object side to the image side, the first lens and the second lens being cemented together, the third lens and the fourth lens being cemented together, and the first lens having an aperture stop in the object side direction; The first lens has positive optical power, with a convex object-side surface and a convex image-side surface; the second lens has negative optical power, with a concave object-side surface and a convex image-side surface; the third lens has positive optical power, with a convex object-side surface and a convex image-side surface; the fourth lens has negative optical power, with a concave object-side surface and a concave image-side surface; and the fifth lens has negative optical power, with a concave object-side surface and a convex image-side surface.

[0006] Optionally, in some embodiments of this application, the total focal length of the optical module is f; the focal length of the first lens is f1, 0.2 < f1 / f < 0.3; the focal length of the second lens is f2, -0.7 < f2 / f < -0.6; the focal length of the third lens is f3, 0.2 < f3 / f < 0.3; the focal length of the fourth lens is f4, -0.2 < f4 / f < -0.1; and the focal length of the fifth lens is f5, -6.7 < f5 / f < -6.6.

[0007] Optionally, in some embodiments of this application, the total focal length of the optical module is f, the parallel light length is TI, and 0.5 < TI / f < 0.6.

[0008] Optionally, in some embodiments of this application, the total focal length of the optical module is f, the back focal length is TL, and 0.7 < TL / f < 0.8.

[0009] Optionally, in some embodiments of this application, the total focal length of the optical module is f, the total length is TR, and 1.4 < TR / f < 1.5.

[0010] Optionally, in some embodiments of this application, the total length of the lens of the optical module is TH, where TH < 45 mm.

[0011] Optionally, in some embodiments of this application, the total focal length of the optical module is f=200mm.

[0012] Optionally, in some embodiments of this application, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all spherical glass lenses.

[0013] In a second aspect, this application provides a semiconductor wafer defect detection device, which includes the optical module described in any one of the first aspects.

[0014] As can be seen from the above technical solutions, the embodiments of this application have the following advantages: This application provides an optical module and a semiconductor wafer defect detection device having the same, employing a 3-group, 5-element lens structure. Specifically, the first lens is a biconvex lens with positive optical power, both the object-side and image-side surfaces are convex; the second lens is a meniscus lens with negative optical power, both the object-side and image-side surfaces are concave; the third lens is a biconvex lens with positive optical power, both the object-side and image-side surfaces are convex; the fourth lens is a biconcave lens with negative optical power, both the object-side and image-side surfaces are concave; and the fifth lens is a meniscus lens with negative optical power, both the object-side and image-side surfaces are concave. The first and second lenses form a cemented lens group, and the third... The first lens and the fourth lens form another set of cemented lenses. An aperture stop is set on the object side of the first lens. Test results show that the full field of view of this optical module is a large 40mm field of view, which is convenient for subsequent observation and testing. The lens group distributes the total optical power in a positive-negative-positive sequence. The negative lens group is used to offset the peak spherical aberration of the positive lens group by reverse deflection, which avoids the excessive spherical aberration caused by excessive deflection of light in a single lens. At the same time, the meniscus shape can adjust the light exit angle, balance the on-axis spherical aberration and off-axis coma and astigmatism, and improve the consistency of image quality across the entire field of view. Furthermore, the combination of positive and negative lenses can use the reverse superposition characteristic of dispersion to reduce axial chromatic aberration across a wide spectrum, realize multi-wavelength confocal, and ensure good image quality. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the lens cross-sectional structure of an optical module provided in an embodiment of this application; Figure 2 An embodiment provided in this application Figure 1 The optical path diagram of the optical module shown is as follows; Figure 3 An embodiment provided in this application Figure 1 The MTF diagram of the optical module shown; Figure 4 An embodiment provided in this application Figure 1 A dot diagram of the optical module shown; Figure 5 An embodiment provided in this application Figure 1 Field curvature and distortion diagrams of the optical module shown; Figure 6 An embodiment provided in this application Figure 1 Axial aberration diagram of the optical module shown; Figure 7 This is a structural block diagram of a semiconductor wafer defect detection device provided in an embodiment of this application. Detailed Implementation

[0017] 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 skilled in the art without creative effort are within the scope of protection of this application.

[0018] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The following examples illustrate this. Figures 1 to 7 The optical module and semiconductor wafer defect detection equipment having the same provided in the embodiments of this application are described in detail.

[0020] Please refer to Figure 1This is a schematic diagram of the lens cross-sectional structure of an optical module provided in an embodiment of this application. The optical module 1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5, which are sequentially distributed along the object-side to the image-side direction. The first lens L1 and the second lens L2 are cemented together, and the third lens L3 and the fourth lens L4 are cemented together. An aperture stop is provided on the object-side direction of the first lens L1. It should be noted that cementing refers to the tight bonding of two lens surfaces of different materials into an optical whole using optical adhesives such as photosensitive adhesives or thermosetting adhesives. The two different materials can be high-refractive-index crown glass and low-refractive-index flint glass. Furthermore, the aperture stop is an aperture in an optical system that limits the width of the imaging beam of an on-axis object point. It determines the effective aperture and the numerical aperture, affecting the imaging brightness, resolution, and aberrations. The light flux can be controlled by adjusting the size. The numerical aperture (NA) is a parameter that measures the light-gathering ability of a lens, which can affect the resolution and imaging quality of the lens.

[0021] In this system, the first lens L1 has positive optical power, with both the object-side and image-side surfaces being convex; the second lens L2 has negative optical power, with both the object-side and image-side surfaces being concave; the third lens L3 has positive optical power, with both the object-side and image-side surfaces being convex; the fourth lens L4 has negative optical power, with both the object-side and image-side surfaces being concave; and the fifth lens L5 has negative optical power, with both the object-side and image-side surfaces being concave. It should be noted that optical power is a physical quantity characterizing the refractive power of an optical system, defined as the difference between the convergence of the image-side beam and the convergence of the object-side beam. Its absolute value is positively correlated with the refractive power of light; the larger the absolute value, the stronger the converging or diverging effect on light, and vice versa. The sign of optical power reflects the characteristics of the light beam; positive values ​​correspond to converging refraction, such as in a convex lens, while negative values ​​correspond to diverging refraction, such as in a concave lens. This concept can be used to describe the refractive characteristics of a single lens, a single lens, or an optical system composed of multiple lenses, such as a lens group. The advantages of this setup are that the total optical power can be allocated in a positive-negative-positive sequence. The negative lens group can be used to counteract the peak spherical aberration of the positive lens group by deflecting the light in the opposite direction. This avoids excessive spherical aberration caused by excessive deflection of light within a single lens. At the same time, the meniscus shape can adjust the light exit angle, balance the on-axis spherical aberration and off-axis coma and astigmatism, and improve the consistency of image quality across the entire field of view. Furthermore, the combination of positive and negative lenses can utilize the inverse superposition characteristic of dispersion to reduce axial chromatic aberration across a wide spectrum, achieving multi-wavelength confocal focusing.

[0022] In some embodiments of this application, the total focal length of the optical module 1 is f, which can be 200mm; the focal length of the first lens L1 is f1, 0.2 < f1 / f < 0.3; the focal length of the second lens L2 is f2, -0.7 < f2 / f < -0.6; the focal length of the third lens L3 is f3, 0.2 < f3 / f < 0.3; the focal length of the fourth lens L4 is f4, -0.2 < f4 / f < -0.1; and the focal length of the fifth lens L5 is f5, -6.7 < f5 / f < -6.6.

[0023] In some embodiments of this application, the total focal length of the optical module 1 is f, which can be 200mm, and the parallel light length is TI. The parallel light length TI refers to the distance from the aperture stop to the center of the front surface of the first lens L1. The front surface of the first lens L1 is close to the object side, and 0.5 < TI / f < 0.6, so the parallel light range is moderate. The advantage of this setting is that it can optimize the incident angle of the beam of medium and high numerical aperture objective lenses, suppress edge beam aberrations, and avoid energy loss caused by excessive divergence, thereby improving the imaging quality and energy uniformity of the entire field of view.

[0024] In some embodiments of this application, the total focal length of the optical module 1 is f, which can be 200mm, and the back focal length is TL. The back focal length TL refers to the distance from the center of the rear surface of the fifth lens L5 to the image plane. The rear surface of the fifth lens L5 is close to the image side, and 0.7 < TL / f < 0.8, which has a long back focal length. The advantage of this setting is that it can balance the image plane position and beam focusing characteristics, suppress aberrations such as field curvature, and leave sufficient space for the installation of subsequent optical components such as beam splitters and filter wheels, thus ensuring the imaging quality of the entire field of view.

[0025] In some embodiments of this application, the total focal length of the optical module 1 is f, which can be 200mm, and the total length is TR. The total length TR refers to the distance from the aperture stop to the image plane. 1.4 < TR / f < 1.5, which has a shorter total length. The advantage of this setting is that it can balance the system compactness and beam transmission efficiency, suppress the accumulation of aberrations in the optical path, and reserve sufficient imaging space to ensure the image quality and structural adaptability of the entire field of view.

[0026] In some embodiments of this application, the total length of the lens of the optical module 1 is TH, which refers to the center distance from the front surface of the first lens L1 to the rear surface of the fifth lens L5. TH < 45mm, and the effective length of the lens group is relatively short. The advantage of this setting is that the lens group can be compacted, the aberration accumulation of the beam transmission between the lenses can be reduced, and the mechanical stability of the system can be improved, making it easier to adapt to the requirements of miniaturized installation.

[0027] In some embodiments of this application, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are all spherical glass lenses. The advantages of this configuration are that spherical lenses have a single curvature, eliminating the need for complex aspherical equation fitting, and have advantages such as low processing cost, high production yield, and symmetrical and uniform structure. They are less prone to edge aberrations due to processing errors. Furthermore, glass lenses have a wide range of refractive index variations and a low dispersion coefficient, which can effectively suppress chromatic aberration and meet the requirements of high-resolution imaging. At the same time, they can maintain stable optical performance at high temperatures, are not prone to distortion due to thermal deformation, and have resistance to chemical corrosion and moisture resistance, which can maintain consistent image quality over a long period of time. In addition, glass is easy to process and shape and optically coated, which helps to further improve optical performance and anti-reflection capabilities.

[0028] The following uses the lens parameters shown in Table 1 as an example, and tests the performance of optical module 1 using Zemax software. A negative radius of curvature indicates the sphere's center is on the object side, and a positive radius of curvature indicates the sphere's center is on the image side. The optical path is as follows: Figure 2 As shown.

[0029] Table 1 Lens Parameters

[0030] from Figures 3 to 6 As can be seen, the optical module 1 in this embodiment corrects aberrations at all levels. The RMS radius in the dot plot is within the Airy disk, and the maximum image plane distortion is less than 0.3%, ensuring high imaging quality. Simultaneously, it has a large 40mm field of view, which can be adapted to the maximum target surface of a 4K imaging sensor. The MTF curves for each field of view are close to the diffraction limit, and the image quality from the center to the edge is good. Furthermore, the spectral range of optical module 1 covers the 450-1000nm band, making it compatible with multimodal imaging from visible light to near-infrared, achieving wide-spectrum aberration collaborative correction, and broadening the spectral dimensions and application scenarios of microscopic detection.

[0031] As another aspect, embodiments of this application provide a semiconductor wafer defect detection device. For example... Figure 7 As shown, the semiconductor wafer defect detection device 2 may include Figures 1 to 6 The optical module 1 in the corresponding embodiment can also be used in scenarios such as confocal microscopes, two-photon microscopes, total internal reflection fluorescence microscopes, and super-resolution microscopy systems. The 200mm focal length design is compatible with infinity optical systems, ensuring that the relay image plane matches the camera target plane and eliminating edge vignetting.

[0032] It should be noted that the descriptions of the same content in this embodiment as in other embodiments can be found in the descriptions in other embodiments, and will not be repeated here.

[0033] The optical module and semiconductor wafer defect detection equipment provided in this application embodiment adopt a 3-group, 5-element lens structure. Specifically, the first lens is a biconvex lens with positive optical power, both the object-side and image-side surfaces are convex; the second lens is a meniscus lens with negative optical power, both the object-side and image-side surfaces are concave; the third lens is a biconvex lens with positive optical power, both the object-side and image-side surfaces are convex; the fourth lens is a biconcave lens with negative optical power, both the object-side and image-side surfaces are concave; and the fifth lens is a meniscus lens with negative optical power, both the object-side and image-side surfaces are convex. The first and second lenses form a cemented lens group, and the third lens... The first lens and the fourth lens form another set of cemented lenses. An aperture stop is set on the object side of the first lens. Test results show that the full field of view of this optical module is a large 40mm field of view, which is convenient for subsequent observation and testing. The lens group distributes the total optical power in a positive-negative-positive sequence. The negative lens group is used to offset the peak spherical aberration of the positive lens group by reverse deflection, avoiding excessive spherical aberration caused by excessive deflection of light in a single lens. At the same time, the meniscus shape can adjust the light exit angle, balance the on-axis spherical aberration and off-axis coma and astigmatism, and improve the consistency of image quality across the entire field of view. Furthermore, the combination of positive and negative lenses can use the reverse superposition characteristic of dispersion to reduce axial chromatic aberration across a wide spectrum, achieving multi-wavelength confocality and ensuring good image quality.

[0034] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An optical module, characterized by comprising: The optical module (1) comprises, in order from the object side to the image side, a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4) and a fifth lens (L5), the first lens (L1) and the second lens (L2) are cemented, the third lens (L3) and the fourth lens (L4) are cemented, and an aperture stop is arranged on the object side of the first lens (L1); The first lens (L1) has positive refractive power, the object side surface is convex, and the image side surface is convex; the second lens (L2) has negative refractive power, the object side surface is concave, and the image side surface is convex; the third lens (L3) has positive refractive power, the object side surface is convex, and the image side surface is convex; the fourth lens (L4) has negative refractive power, the object side surface is concave, and the image side surface is concave; and the fifth lens (L5) has negative refractive power, the object side surface is concave, and the image side surface is convex.

2. The optical module according to claim 1, wherein The total focal length of the optical module (1) is f; the focal length of the first lens (L1) is f1, 0.2 < f1 / f < 0.3; the focal length of the second lens (L2) is f2, -0.7 < f2 / f < -0.6; the focal length of the third lens (L3) is f3, 0.2 < f3 / f < 0.3; the focal length of the fourth lens (L4) is f4, -0.2 < f4 / f < -0.1; and the focal length of the fifth lens (L5) is f5, -6.7 < f5 / f < -6.

6.

3. The optical module according to claim 1, wherein The total focal length of the optical module (1) is f, and the parallel light length is TI, 0.5 < TI / f < 0.

6.

4. The optical module according to claim 1, wherein The total focal length of the optical module (1) is f, and the back focal length is TL, 0.7 < TL / f < 0.

8.

5. The optical module according to claim 1, wherein The total focal length of the optical module (1) is f, and the total length is TR, 1.4 < TR / f < 1.

5.

6. The optical module according to claim 1, wherein The total length of the lenses of the optical module (1) is TH, TH < 45 mm.

7. The optical module according to any one of claims 1 to 6, wherein The total focal length of the optical module (1) is f = 200 mm.

8. The optical module according to any one of claims 1 to 6, wherein The first lens (L1), the second lens (L2), the third lens (L3), the fourth lens (L4) and the fifth lens (L5) are all spherical glass lenses.

9. A semiconductor wafer defect detection apparatus characterized by comprising: The semiconductor wafer defect detection device (2) comprises the optical module (1) of any one of claims 1 to 8.

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