CN117872576B - Line scanning confocal microscopic system - Google Patents
Line scanning confocal microscopic system Download PDFInfo
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- CN117872576B CN117872576B CN202410226269.5A CN202410226269A CN117872576B CN 117872576 B CN117872576 B CN 117872576B CN 202410226269 A CN202410226269 A CN 202410226269A CN 117872576 B CN117872576 B CN 117872576B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/0004—Microscopes specially adapted for specific applications
- G02B21/002—Scanning microscopes
- G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
- G02B21/0032—Optical details of illumination, e.g. light-sources, pinholes, beam splitters, slits, fibers
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/0004—Microscopes specially adapted for specific applications
- G02B21/002—Scanning microscopes
- G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
- G02B21/0036—Scanning details, e.g. scanning stages
- G02B21/0048—Scanning details, e.g. scanning stages scanning mirrors, e.g. rotating or galvanomirrors, MEMS mirrors
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/0004—Microscopes specially adapted for specific applications
- G02B21/002—Scanning microscopes
- G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
- G02B21/0052—Optical details of the image generation
- G02B21/0072—Optical details of the image generation details concerning resolution or correction, including general design of CSOM objectives
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/24—Base structure
- G02B21/26—Stages; Adjusting means therefor
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Abstract
The application relates to a line scanning confocal microscopy system, comprising: a light source assembly; the first lens group is arranged on the light emitting side of the light source assembly along the first direction and comprises a beam splitting prism, the beam splitting prism comprises a first surface and a second surface which are opposite, and the first surface faces the light source assembly; the high-speed scanning vibrating mirror is arranged on one side of the first mirror group, which is away from the light source assembly along the first direction, and comprises a reflecting surface, wherein the reflecting surface faces the first mirror group; the high-speed scanning galvanometer is movably arranged along a first direction; the second lens group is arranged at one side of the high-speed scanning vibrating mirror along the second direction and comprises a four-focal-length lens group; the objective lens is arranged at one side of the second lens group, which is away from the high-speed scanning galvanometer along the second direction; the bearing component is arranged at one side of the objective lens, which is away from the second lens group along the second direction; the imaging component is arranged on one side of the first lens group along the second direction, and the second surface faces the imaging component. The line scanning confocal microscopic system disclosed by the application can improve the wafer detection efficiency.
Description
Technical Field
The application relates to the technical field of wafer detection, in particular to a line scanning confocal microscopic system.
Background
Wafer defect detection has extremely important applications in semiconductor manufacturing, and by detecting defects of wafers, wafer quality is ensured, and yield and reliability of chip manufacturing are improved. During inspection, the wafer is typically observed and inspected using a wide field metallographic optical microscope. This approach may identify some larger defects, such as surface defects or roughness variations, but may not be sufficiently sensitive to small defects on the sub-micron scale, with a low contrast. In addition, the method needs to photograph and splice wafers in small fields one by one, the speed is low, and the efficiency is low because 2 to 3 hours are needed for large-area full-scan imaging detection of an 8-inch wafer.
Disclosure of Invention
In view of the above, the present application is directed to a line scanning confocal microscope system for improving wafer inspection efficiency.
The aim of the application is mainly realized by the following technical scheme:
The embodiment of the application provides a line scanning confocal microscopic system, which comprises the following components: a light source assembly emitting laser light in a first direction; the first lens group is arranged on the light emitting side of the light source assembly along the first direction and comprises a beam splitting prism, the beam splitting prism comprises a first surface and a second surface which are opposite, and the first surface faces the light source assembly; the high-speed scanning vibrating mirror is arranged on one side of the first mirror group, which is away from the light source assembly along the first direction, and comprises a reflecting surface, wherein the reflecting surface faces the first mirror group; the high-speed scanning galvanometer is movably arranged along a first direction; the second lens group is arranged at one side of the high-speed scanning vibrating mirror along the second direction and comprises a four-focal-length lens group; the first direction is perpendicular to the second direction; the objective lens is arranged at one side of the second lens group, which is away from the high-speed scanning galvanometer along the second direction; the bearing assembly is arranged at one side of the objective lens, which is away from the second lens group along the second direction; the imaging component is arranged on one side of the first lens group along the second direction, and the second surface faces the imaging component.
According to the embodiment of the application, the light source component comprises a laser light source and a Bawilt lens; the laser light source emits laser rays along a first direction; the Bawil lens is arranged on the light emitting side of the laser light source along the first direction.
According to the embodiment of the application, the wavelength of the laser ray emitted by the laser source is 405nm, and the diameter of an output light spot is 1.5mm; the angle of emission of the powell lens is 18 ° and the diameter is 10mm.
According to the embodiment of the application, the first lens group further comprises a first lens and a second lens, the first lens is arranged between the light source component and the beam-splitting prism, and the second lens is arranged between the beam-splitting prism and the high-speed scanning galvanometer; the light-splitting prism is configured such that light incident from the first surface can be emitted from the second surface, and light incident from the second surface is reflected at the second surface.
According to the embodiment of the application, the first lens is a plano-convex lens, and the focal length of the first lens is 30mm; the second lens is a plano-convex lens, and the focal length of the second lens is 50mm.
According to the embodiment of the application, the second mirror group further comprises a first reflecting mirror and a second reflecting mirror, the first reflecting mirror is arranged on one side of the high-speed scanning vibrating mirror along the second direction, and the first reflecting mirror, the four-focal-length lens and the second reflecting mirror are sequentially arranged along the first direction; the fourth focal length lens group comprises a fourth lens and a third lens which are coaxially arranged along the first direction, and the third lens is positioned between the first reflecting mirror and the fourth lens.
According to the embodiment of the application, the third lens is a plano-convex lens, and the focal length of the third lens is 100mm; the fourth lens is a plano-convex lens, and the focal length of the fourth lens is 180mm; the distance between the third lens and the first mirror in the first direction is 100mm.
According to the embodiment of the application, the imaging component comprises a camera, a fifth lens and a sixth lens, wherein the fifth lens is arranged on one side of the first lens group along the second direction, and the camera, the sixth lens and the fifth lens are coaxially arranged in sequence along the second direction.
According to the embodiment of the application, the fifth lens is a plano-convex lens, and the focal length of the fifth lens is 50mm; the sixth lens is a plano-convex lens, and the focal length of the fifth lens is 200mm; in the second direction, the distance between the camera and the sixth lens is 200mm.
According to an embodiment of the application, the carrier assembly includes an electrically powered wafer stage that is disposed for reciprocal movement along a first direction
The line scanning confocal microscope system provided by the embodiment of the application has at least the following advantages:
1. The light source component adopts a laser light source, the imaging of an image surface is uniform, the brightness is high, the single-image view field is large, the single-line scanning covers the whole wafer, and the offline view field of the objective lens is 1.1mm by 20 times.
2. The application has the rapid scanning capability, can complete single-line single-image scanning of 8-inch wafers within 0.5s, can complete scanning imaging of the whole wafer under the 20-time objective lens within 90s, and covers imaging of the whole wafer surface, thereby improving detection efficiency.
3. The application adopts the principle of confocal microscopic detection light path, and utilizes the single-column pixel switch of the linear array camera to realize slit function, thereby realizing high-resolution imaging, more accurately detecting and positioning tiny defects or foreign matters on the surface of the wafer and ensuring high-quality production.
4. Through optical design verification, the divergence angle of the Powell lens and the focal length of the lens group are favorable for correcting aberration, improving uniformity of line illumination and improving image quality of the whole view field, so that resolution, transmittance and image uniformity of the optical imaging system are remarkably improved.
5. The XY-axis electric table disclosed by the application has the advantages of high stability, high repeatability and good linearity, solves the problem of image distortion caused by uneven speed and inaccurate positioning in the line scanning imaging process, and simultaneously has a miniaturized and light vacuum wafer clamping platform, and can adapt to different wafer sizes of 6 inches, 8 inches and 12 inches.
In the application, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application. The objectives and other advantages of the application may be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the application, like reference numerals being used to refer to like parts throughout the several views.
Fig. 1 is a schematic diagram of a line scanning confocal microscopy system according to an embodiment of the application.
Fig. 2 is a schematic structural diagram of a line scanning confocal microscopy system according to an embodiment of the application.
Fig. 3 is an image of a wafer obtained by a line scanning confocal microscopy system according to an embodiment of the application.
Reference number:
1. a light source assembly; 11. a laser light source; 12. baowier lens
2. A first lens group; 21. a beam-splitting prism; 211. a first face; 212. a second face; 22. a first lens; 23. a second lens;
3. A high-speed scanning galvanometer;
4. a second lens group; 41. a four focal length lens group; 411. a third lens; 412. a fourth lens; 42. a first mirror; 43. a second mirror;
5. An objective lens;
6. a carrier assembly;
7. an imaging assembly; 71. a camera; 72. a fifth lens; 73. a sixth lens;
X, a first direction; y, second direction.
Detailed Description
Features and exemplary embodiments of various aspects of the application are described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the application. It will be apparent, however, to one skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the application by showing examples of the application.
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The embodiments will be described in detail below with reference to the accompanying drawings.
Relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
It will be understood that when a layer, an area, or a structure is described as being "on" or "over" another layer, another area, it can be referred to as being directly on the other layer, another area, or another layer or area can be included between the layer and the other layer, another area. And if the component is turned over, that layer, one region, will be "under" or "beneath" the other layer, another region.
In addition, the term "and/or" herein is merely an association relationship describing an association object, and means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
It should be understood that in embodiments of the present application, "B corresponding to a" means that B is associated with a, from which B may be determined. It should also be understood that determining B from a does not mean determining B from a alone, but may also determine B from a and/or other information.
Applicants have found that wafer inspection typically uses a wide field metallographic optical microscope to observe and inspect the wafer for defects. In the process of detecting the wafer, the wafer range is divided into a plurality of small-range visual fields, a wide-field metallographic optical microscope is used for observing the wafer to shoot and image in one small-range visual field, then the images of all the small-range visual fields are spliced to form an integral image of the wafer, and whether the wafer has defects is judged according to the images. However, due to the smaller visual field range, the method needs to photograph and splice wafers in a small visual field one by one, and the speed is low. For example, inspection of an 8 inch wafer takes 2 to 3 hours. In addition, when the wafer images corresponding to different fields of view are spliced, larger defects such as surface defects or roughness changes can be identified, but the wafer images may not be sensitive enough to submicron-level small defects, and the contrast is low.
In view of the above analysis, applicants have proposed a line scanning confocal microscopy system comprising a light source assembly, a first mirror set, a high-speed scanning galvanometer, a second mirror set, an objective lens, a carrier assembly, and an imaging assembly. The laser emitted by the light source assembly passes through the first lens group and is transmitted from the second surface of the beam splitting prism, and then is reflected at the high-speed scanning galvanometer, and the reflected light passes through the second lens group and the objective lens to form a uniform linear light source. Along with the movement of the high-speed scanning galvanometer, the linear light source can scan the wafer to scan line by line. After the light is reflected by the wafer, the light passes through the objective lens and the second lens group again, the high-speed scanning galvanometer emits reflection, and when the reflected light passes through the first lens group, the light is reflected by the second reflection of the beam-splitting prism, and then is emitted to the imaging assembly, so that the resolution, the transmittance and the uniformity of an image obtained by the imaging assembly are obviously improved. The line scanning confocal microscope system provided by the embodiment of the application can shoot the wafer row by row when detecting the wafer, and can detect one row on the wafer at the same time, so that the efficiency of detecting the wafer can be greatly improved.
Fig. 1 is a schematic diagram of a line scanning confocal microscopy system according to an embodiment of the application.
Referring to fig. 1, an embodiment of the present application provides a line scanning confocal microscopy system, including: a light source assembly 1 that emits laser light in a first direction X; the first lens group 2 is arranged on the light emitting side of the light source assembly 1 along the first direction X, the first lens group 2 comprises a beam splitting prism 21, the beam splitting prism 21 comprises a first surface 211 and a second surface 212 which are opposite, and the first surface 211 faces the light source assembly 1; the high-speed scanning galvanometer 3 is arranged on one side of the first lens group 2, which is away from the light source assembly 1 along the first direction X, and the high-speed scanning galvanometer 3 comprises a reflecting surface, wherein the reflecting surface faces the first lens group 2; a second lens group 4 disposed at one side of the high-speed scanning galvanometer 3 along the second direction Y, the second lens group 4 including a four-focal-length lens group 41; the first direction X is perpendicular to the second direction Y; the objective lens 5 is arranged at one side of the second lens group 4, which is away from the high-speed scanning galvanometer 3 along the second direction Y; the bearing component 6 is arranged on one side of the objective lens 5, which is away from the second lens group 4 along the second direction Y; the imaging component 7 is arranged on one side of the first lens group 2 along the second direction Y, and the second surface 212 faces the imaging component 7.
In the embodiment of the present application, the first direction X and the second direction Y are perpendicular to each other, the wafer is placed on the carrier assembly 6, the plane on which the wafer is located may be perpendicular to the vertical direction in consideration of the stability of the wafer on the carrier assembly 6, that is, the second direction Y may be the vertical direction, the first direction X may be the horizontal direction,
The light source component 1 is used for emitting laser light, the laser light is a linear light source, after the linear light source finally irradiates the wafer, a line of area of the wafer can be illuminated, the linear light source is used for imaging the imaging component 7, the obtained image corresponds to a line of the wafer, and the line of the wafer can be checked to confirm whether the line of the wafer has defects.
The first lens group 2 is arranged on the light emitting side of the light source assembly 1 along the first direction X, and the first lens group 2 is combined through the lens, so that the uniformity of the line light source can be improved on the premise that the brightness of the line light source is ensured, and the brightness and the definition of a certain line of the wafer are basically consistent after the line light source irradiates the wafer, so that the definition and the uniformity of an image obtained by the imaging assembly 7 are improved, and the accuracy and the reliability of wafer detection by using the line scanning confocal microscopic system provided by the embodiment of the application are further improved. The linear light source is incident from the first surface 211 of the beam splitter prism 21 and is emitted from the second surface 212, and the beam splitter prism 21 does not significantly affect the optical path of the linear light source.
The high-speed scanning galvanometer 3 is arranged on one side of the first lens group 2, which is away from the light source component 1 along the first direction X, and the reflecting surface of the high-speed scanning galvanometer 3 can reflect the linear light source which is irradiated along the first direction X, so that the linear light source is irradiated along the second direction Y. The high-speed scanning galvanometer 3 can move along the first direction X so that a subsequent light path of the line light source moves along the first direction X, and can irradiate the wafer line by line, thereby realizing the purpose of line-by-line scanning imaging of the wafer. Because the line light source can irradiate the whole row of the wafer, the imaging times in the single wafer detection process can be reduced, and the wafer detection efficiency is further improved. For example, the lens size of the high-speed scanning galvanometer 3 can be 10mm, the lens type is silver mirror, single-line single-image scanning of an 8-inch wafer can be completed within 0.5s, scanning imaging of the whole wafer under the 20-time objective lens 5 can be completed within 90s, and imaging of the whole wafer surface is covered, so that the detection efficiency is improved.
The second lens group 4 is arranged on one side of the high-speed scanning vibrating mirror 3 along the second direction Y, and the uniformity of the line light source can be improved on the premise that the brightness of the line light source is ensured by the four-focal-length lens group 41 of the second lens group 4, and the brightness and the definition of a certain line of the wafer are basically consistent after the line light source irradiates the wafer, so that the definition and the uniformity of an image obtained by the imaging component 7 are improved. In addition, when imaging the wafer, the imaged light rays also pass through the second lens group 4, so that the image quality of the whole wafer image is improved, and the resolution, the transmittance and the uniformity of the wafer image obtained by the line scanning confocal microscope system of the embodiment of the application are obviously improved.
The objective lens 5 is arranged on one side of the second lens group 4, which is away from the high-speed scanning galvanometer 3 along the second direction Y, and can be close to or far away from the wafer positioned on the bearing component 6 along the second direction Y, so that focusing imaging of the wafer is realized.
The imaging assembly 7 is disposed on one side of the first lens group 2 along the second direction Y, and is used for finally obtaining an image of the wafer. The line light source reflects after irradiating a certain line of the wafer, and after passing through the second lens group 4 and the high-speed scanning galvanometer 3, the reflected light irradiates the first lens group 2 along the first direction X and is reflected on the second surface 212 of the beam splitting prism 21, and after being reflected, the light irradiates the imaging component 7 along the second direction Y, so that the imaging component 7 can obtain an image of the line of the wafer. As the high-speed scanning galvanometer 3 moves in the first direction X, the light source assembly 1 illuminates the wafer line by line and the imaging assembly 7 images the wafer line by line, thereby obtaining a complete image of the wafer and for use in terminating the wafer for the presence of defects.
Fig. 2 is a schematic structural diagram of a line scanning confocal microscopy system according to an embodiment of the application.
Further, referring to fig. 2, the light source assembly 1 includes a laser light source 11 and a powell lens 12; the laser light source 11 emits laser light in a first direction X; the powell lens 12 is disposed on the light-emitting side of the laser light source 11 along the first direction X.
The laser light source 11 of the light source assembly 1 can emit a circular light spot, and the light spot has uniform overall brightness and is used for forming a linear light source. After the light spot emitted by the laser light source 11 irradiates the powell lens 12, the light spot can form a uniformly irradiated linear light source, the linear light source can illuminate a certain row of a wafer and is used for confocal imaging, and the obtained image of the wafer row can also have good definition, resolution and uniformity.
Further, with continued reference to fig. 2, the wavelength of the laser beam emitted by the laser light source 11 is 405nm, and the output spot diameter is 1.5mm; the angle of emission of the powell lens 12 is 18 ° and the diameter is 10mm.
In the embodiment of the application, the laser light source 11 can be a semiconductor single-mode space light collimation laser, forms laser spots with stable wavelength and brightness, has uniform imaging on an image surface, high brightness and large single-image view field, covers a whole wafer by single-line scanning, and has a 20-time objective lens 5 offline view field of 1.1mm. The wavelength of the laser spot is 405nm and the diameter of the laser spot is 1.5mm, for example. Considering that the light spot of the laser light source 11 is used as a confocal imaging light source, the power of the laser light source 11 should have a certain stability, and the power stability index should be lower than 1%, so that the brightness, the definition and the resolution of images obtained by different rows of the wafer are kept substantially consistent, thereby improving the uniformity of the wafer images obtained by the line scanning confocal microscopy system of the embodiment of the application. Furthermore, the output power of the laser light source 11 should be adjustable, for example, in the range of 0-20mW with an accuracy of 0.1%. By adjusting the output power of the laser light source 11, an image with both brightness and sharpness can be obtained by the imaging module 7.
The emission angle of the powell lens 12 may be 18 °, so that the line light source emitted from the powell lens 12 can illuminate the whole line of the wafer, and the illumination range is not too large, and the detection range of the objective lens 5 is not exceeded, which is beneficial to aberration correction and improves uniformity of line illumination. In addition, the diameter size of the powell lens 12 may be 10mm, and the maximum diameter of the adapted incident light spot is 2mm, so that the light spot emitted by the laser light source 11 can be adapted to the powell lens 12, and a linear light source with uniform brightness is emitted.
Further, with continued reference to fig. 2, the first lens group 2 further includes a first lens 22 and a second lens 23, the first lens 22 is disposed between the light source assembly 1 and the beam splitting prism 21, and the second lens 23 is disposed between the beam splitting prism 21 and the high-speed scanning galvanometer 3; the dichroic prism 21 is configured such that light incident from the first surface 211 can be emitted from the second surface 212, and light incident from the second surface 212 is reflected at the second surface 212.
The first lens 22 is disposed between the light source unit 1 and the beam splitter prism 21, and the second lens 23 is disposed between the beam splitter prism 21 and the high-speed scanning galvanometer 3. When the line light source enters from the first surface 211 of the beam splitter prism 21, it can be emitted from the second surface 212, and therefore, the beam splitter prism 21 does not affect the conduction of the line light source between the first lens 22 and the second lens 23. The first lens 22 and the second lens 23 form a 4F system, and can filter the line light source, so that uniformity of the line light source is improved, and images obtained by the line scanning confocal microscope system of the embodiment of the application are more uniform.
Further, with continued reference to fig. 2, the first lens 22 is a plano-convex lens, and the focal length of the first lens 22 is 30mm; the second lens 23 is a plano-convex lens, and the focal length of the second lens 23 is 50mm.
In the embodiment of the present application, the first lens 22 and the second lens 23 may be positive lenses, and each may be in the form of a plano-convex lens. Considering that the first lens 22 and the second lens 23 form a 4F system, the distance between the first lens 22 and the second lens 23 in the first direction X is equal to the sum of the focal length of the first lens 22 and the focal length of the second lens 23, i.e., 80mm.
Further, with continued reference to fig. 2, the second lens group 4 further includes a first mirror 42 and a second mirror 43, where the first mirror 42 is disposed on one side of the high-speed scanning galvanometer 3 along the second direction Y, and the first mirror 42, the four-focal-length lens, and the second mirror 43 are sequentially arranged along the first direction X; the four-focal-length lens group 41 includes a fourth lens 412 and a third lens 411 coaxially disposed along the first direction X, the third lens 411 being located between the first mirror 42 and the fourth lens 412.
After being reflected by the high-speed scanning galvanometer 3, the linear light source is directed to the first reflecting mirror 42 along the second direction Y and reflected towards the first direction X, passes through the four-focal-length lens group 41, is directed to the second reflecting mirror 43 along the first direction X and reflected towards the second direction Y, and then irradiates the surface of the wafer. By adjusting the positions of the first mirror 42 and the second mirror 43, the line light source can be enabled to irradiate all areas of the wafer, so that the imaging assembly 7 can obtain images of all areas of the wafer to determine whether the wafer has defects. The fourth lens 412 and the third lens 411 form a 4F system, and the line light source may be filtered, thereby improving uniformity of the line light source. In the imaging process, the light reflected by the wafer passes through the second lens group 4 again, and the 4F system formed by the fourth lens 412 and the third lens 411 can filter the light reflected by the wafer again, so that the image obtained by the line scanning confocal microscope system of the embodiment of the application is more uniform.
Further, with continued reference to fig. 2, the third lens 411 is a plano-convex lens, and the focal length of the third lens 411 is 100mm; the fourth lens 412 is a plano-convex lens, and the focal length of the fourth lens 412 is 180mm; the distance between the third lens 411 and the first mirror 42 in the first direction X is 100mm.
In the embodiment of the present application, the third lens 411 and the fourth lens 412 may be positive lenses, and all take the form of plano-convex lenses. Considering that the third lens 411 and the fourth lens 412 form a 4F system, the distance between the third lens 411 and the fourth lens 412 in the first direction X is equal to the sum of the focal length of the first lens 22 and the focal length of the second lens 23, i.e., 280mm. In addition, considering that the high-speed scanning galvanometer 3 and the first reflecting mirror 42 both change the direction of the light path by reflection, the second lens 23 and the third lens 411 can also form a 4F system, which can filter the line light source, thereby improving the uniformity of the line light source, and can filter the light reflected by the wafer again, thereby making the image obtained by the line scanning confocal microscope system of the embodiment of the application more uniform.
Further, with continued reference to fig. 2, the imaging assembly 7 includes a camera 71, a fifth lens 72 and a sixth lens 73, the fifth lens 72 is disposed on one side of the first lens group 2 along the second direction Y, and the camera 71, the sixth lens 73 and the fifth lens 72 are sequentially coaxially disposed along the second direction Y.
The light reflected by the wafer passes through the second lens group 4 and the high-speed scanning galvanometer 3, then passes through the second lens 23, irradiates the second surface 212 of the beam splitter prism 21 along the first direction X, is reflected by the second surface 212, and is emitted to the camera 71 along the second direction Y through the fifth lens 72 and the sixth lens 73 for confocal imaging, so as to obtain an image of a certain line of the wafer. The second lens 23 and the fifth lens 72 may form a 4F system, and the sixth lens 73 and the fifth lens 72 may also form a 4F system. Both can filter the light reflected by the wafer, so that the image obtained by the line scanning confocal microscopy system of the embodiment of the application is more uniform.
Further, with continued reference to fig. 2, the fifth lens 72 is a plano-convex lens, and the focal length of the fifth lens 72 is 50mm; the sixth lens 73 is a plano-convex lens, and the focal length of the fifth lens 72 is 200mm; in the second direction Y, the distance between the camera 71 and the sixth lens 73 is 200mm.
In the embodiment of the present application, the fifth lens 72 and the sixth lens 73 may be positive lenses, and each take the form of a plano-convex lens. Considering that the second lens 23 and the fifth lens 72 form a 4F system, the sum of the distance between the beam-splitting prism 21 and the second lens 23 in the first direction X and the distance between the beam-splitting prism 21 and the fifth lens 72 in the second direction Y is equal to the sum of the focal length of the second lens 23 and the focal length of the fifth lens 72, i.e., 100mm. Considering that the sixth lens 73 and the fifth lens 72 form a 4F system, the distance of the sixth lens 73 from the fifth lens 72 in the second direction Y is equal to the sum of the focal length of the sixth lens 73 and the focal length of the fifth lens 72, i.e., 250mm.
The camera 71 may be a linear array back-illuminated CCD camera 71, and as an imaging device according to an embodiment of the present application, there may be 8192 pixels corresponding to a line direction of a wafer, the minimum line time is 4 μs, the dynamic range is >66.7dB, and the maximum line speed is 200kHz. The distance between the camera 71 and the sixth lens 73 is 200mm. So that the camera 71 can obtain an image with high definition and resolution, and is convenient for judging whether the wafer has tiny defects.
Further, with continued reference to fig. 2, the carrier assembly 6 includes a motorized wafer stage reciprocally disposed along the first direction X.
The carrier assembly 6 is used to carry wafers and may employ an electrically powered wafer stage, for example, an electrically powered wafer stage carrying 10-20kg. The motorized wafer stage can be moved in a direction perpendicular to the first direction X and the second direction Y in addition to the first direction X, and the effective stroke of movement in both directions is 300X300mm, the resolution is 1 μm, the linear speed is 50mm/s, and the repetition accuracy is 2 μm, so that the line light source can illuminate all positions of the wafer, and the camera 71 of the imaging assembly 7 can also image all positions of the wafer. The electric wafer stage has high stability and high repeatability, good linearity, solves the problem of image distortion caused by uneven speed and inaccurate positioning in the line scanning imaging process, and simultaneously has a miniaturized and light vacuum wafer clamping platform which can adapt to different wafer sizes of 6 inches, 8 inches and 12 inches.
Fig. 3 is an image of a wafer obtained by a line scanning confocal microscopy system according to an embodiment of the application.
The line scanning confocal microscopic system provided by the embodiment of the application is used for detecting a certain wafer product, so that an image of the wafer can be obtained. A portion of the image of the wafer is shown in fig. 3. The wafer image in fig. 3 has a large field of view, and a line field of view of up to 1.1mm at 20 x the objective. In addition, the wafer image in FIG. 3 has higher overall definition and good uniformity, the distortion is not higher than 10% under the whole view field, and the distortion is controlled in a smaller range, so that the requirement of wafer defect characteristic identification on the distortion is met.
In summary, the embodiment of the application provides a line scanning confocal microscope system, wherein laser emitted by a light source assembly passes through a first lens group and is transmitted from a second surface of a beam splitting prism, and then is reflected at a high-speed scanning galvanometer, and the reflected light passes through a second lens group and an objective lens to form a uniform line light source. Along with the movement of the high-speed scanning galvanometer, the linear light source can scan the wafer to scan line by line. After the light is reflected by the wafer, the light passes through the objective lens and the second lens group again, the high-speed scanning galvanometer emits reflection, and when the reflected light passes through the first lens group, the light is reflected by the second reflection of the beam-splitting prism, and then is emitted to the imaging assembly, so that the resolution, the transmittance and the uniformity of an image obtained by the imaging assembly are obviously improved. The line scanning confocal microscope system provided by the embodiment of the application can shoot the wafer row by row when detecting the wafer, and can detect one row on the wafer at the same time, so that the efficiency of detecting the wafer can be greatly improved.
The present application is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present application are intended to be included in the scope of the present application.
Claims (6)
1. A line scanning confocal microscopy system for wafer inspection, comprising:
The light source assembly emits laser light along a first direction, presents a linear light source and illuminates a row of areas of the wafer; the light source assembly comprises a laser light source and a Bawil lens; the laser light source emits laser rays along the first direction; the Bawil lens is arranged on the light emitting side of the laser light source along the first direction; the wavelength of the laser rays emitted by the laser source is 405nm, and the diameter of the output light spot is 1.5mm; the emission angle of the Bawilt lens is 18 degrees, and the diameter is 10mm;
The first lens group is arranged on the light emitting side of the light source assembly along the first direction, and comprises a beam splitting prism, wherein the beam splitting prism comprises a first surface and a second surface which are opposite, and the first surface faces the light source assembly; the high-speed scanning vibrating mirror is arranged on one side, away from the light source assembly, of the first mirror group along the first direction, and comprises a reflecting surface, wherein the reflecting surface faces the first mirror group; the high-speed scanning galvanometer is movably arranged along the first direction;
The second lens group is arranged at one side of the high-speed scanning galvanometer along the second direction and comprises a four-focal-length lens group; the first direction is perpendicular to the second direction; the second lens group further comprises a first reflecting mirror and a second reflecting mirror, the first reflecting mirror is arranged on one side of the high-speed scanning vibrating mirror along the second direction, and the first reflecting mirror, the four-focal-length lens and the second reflecting mirror are sequentially arranged along the first direction; the four-focal-length lens group comprises a fourth lens and a third lens which are coaxially arranged along the first direction, and the third lens is positioned between the first reflecting mirror and the fourth lens;
The objective lens is arranged at one side of the second lens group, which is away from the high-speed scanning galvanometer along the second direction;
The bearing assembly is arranged at one side of the objective lens, which is away from the second lens group along the second direction;
The imaging assembly is arranged on one side of the first lens group along the second direction, and the second surface faces the imaging assembly; the imaging assembly comprises a camera, a fifth lens and a sixth lens, the fifth lens is arranged on one side of the first lens group along the second direction, and the camera, the sixth lens and the fifth lens are coaxially arranged in sequence along the second direction; the second lens and the fifth lens form a 4-time focal length system; the sixth lens and the fifth lens form a 4-fold focal length system.
2. The line scanning confocal microscopy system of claim 1, wherein,
The beam splitting prism is configured such that light incident from the first surface can be emitted from the second surface, and light incident from the second surface is reflected at the second surface.
3. The line scanning confocal microscopy system of claim 2, wherein the first lens is a plano-convex lens, the focal length of the first lens being 30mm;
the second lens is a plano-convex lens, and the focal length of the second lens is 50mm.
4. The line scanning confocal microscopy system of claim 3, wherein the third lens is a plano-convex lens, the third lens having a focal length of 100mm;
the fourth lens is a plano-convex lens, and the focal length of the fourth lens is 180mm;
The distance between the third lens and the first mirror is 100mm along the first direction.
5. The line scanning confocal microscopy system of claim 4, wherein the fifth lens is a plano-convex lens, the focal length of the fifth lens being 50mm;
the sixth lens is a plano-convex lens, and the focal length of the fifth lens is 200mm;
in the second direction, a distance between the camera and the sixth lens is 200mm.
6. The line scan confocal microscopy system of claim 1, wherein the carrier assembly comprises a motorized wafer stage that is reciprocally disposed along the first direction.
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| CN117137433A (en) * | 2023-07-10 | 2023-12-01 | 深圳信息职业技术学院 | Multi-wavelength confocal speckle imaging system, method, storage medium and equipment |
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| CN116755234A (en) * | 2023-08-17 | 2023-09-15 | 浙江荷湖科技有限公司 | Linear light scanning confocal microscopic imaging system and linear light scanning confocal microscopic imaging method |
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