CN114415325A - Focusing optical imaging system - Google Patents
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- CN114415325A CN114415325A CN202210161373.1A CN202210161373A CN114415325A CN 114415325 A CN114415325 A CN 114415325A CN 202210161373 A CN202210161373 A CN 202210161373A CN 114415325 A CN114415325 A CN 114415325A
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- 238000012634 optical imaging Methods 0.000 title claims abstract description 42
- 230000003287 optical effect Effects 0.000 claims abstract description 73
- 230000008859 change Effects 0.000 claims abstract description 8
- 238000005259 measurement Methods 0.000 claims description 60
- 238000003384 imaging method Methods 0.000 claims description 41
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
- G02B7/09—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification adapted for automatic focusing or varying magnification
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/28—Systems for automatic generation of focusing signals
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Abstract
A focusing optical imaging system relates to the technical field of optics, and comprises a marking plate, a first focusing lens group, a second focusing lens group, a barrel lens, an objective lens and an object space plane plate, wherein the marking plate, the first focusing lens group, the second focusing lens group, the barrel lens and the objective lens are sequentially arranged at intervals along a first optical axis direction; the object space plane plate is configured to be capable of moving along a first optical axis direction to change an optical axis distance between the object space plane plate and the objective lens; the focusing optical imaging system also comprises a third focusing lens group and an image acquisition device which are sequentially arranged along the direction of the second optical axis; the first optical axis direction is vertical to the second optical axis direction; a folding reflector is arranged between the first focusing lens group and the second focusing lens group; the deflection reflector is configured to reflect the light transmitted along the first optical axis direction into the light transmitted along the second optical axis direction; the marking plate is provided with a measuring marking hole. The invention aims to provide a focusing optical imaging system to solve the technical problems of long focusing time and poor focusing accuracy in the prior art to a certain extent.
Description
Technical Field
The invention relates to the technical field of optics, in particular to a focusing optical imaging system.
Background
With the improvement of semiconductor manufacturing nodes, the requirements on the silicon wafer alignment imaging optical system are higher and higher, and especially for the silicon wafer alignment imaging optical system based on the image recognition technology, the accuracy of automatic focusing is the key for determining the alignment imaging optical system. Most of the existing common automatic focusing technologies adopt a technical route of a software algorithm, and the main principle is to collect an image aligned with an imaging optical system, extract the contrast of the image, collect the image again after adjusting the distance to calculate the contrast, determine the optimal contrast position after multiple iterations, and complete the automatic focusing work at the moment. However, the scheme needs to adjust the axial distance for multiple times and gradually converge and step to complete the whole automatic focusing process, has the disadvantages of long adjusting time, insufficient adjusting precision and the like, and has the risk of failure of automatic focusing work under the condition of relatively serious defocusing.
Disclosure of Invention
The invention aims to provide a focusing optical imaging system to solve the technical problems of long focusing time and poor focusing accuracy in the prior art to a certain extent.
In order to achieve the purpose, the invention provides the following technical scheme:
a focusing optical imaging system comprises a marking plate, a first focusing lens group, a second focusing lens group, a tube lens, an objective lens and an object space plane plate, wherein the marking plate, the first focusing lens group, the second focusing lens group, the tube lens, the objective lens and the object space plane plate are sequentially arranged at intervals along a first optical axis direction; the object plane plate is configured to be movable in a first optical axis direction to change an optical axis distance between the object plane plate and the objective lens;
the focusing optical imaging system also comprises a third focusing lens group and an image acquisition device which are sequentially arranged along the direction of a second optical axis; the first optical axis direction is perpendicular to the second optical axis direction;
a folding reflector is arranged between the first focusing mirror group and the second focusing mirror group; the folding reflector is configured to reflect the light transmitted along the first optical axis direction into the light transmitted along the second optical axis direction;
the marking plate is provided with a measuring marking hole; light rays penetrate through the measuring mark holes to form measuring incident light rays, and the measuring incident light rays sequentially penetrate through the first focusing lens group, the second focusing lens group, the tube lens and the objective lens and are incident to an object to be measured on the object space plane plate at a certain incident angle; the measuring incident light is reflected by an object to be measured on the object space plane plate to form measuring reflected light, the measuring reflected light sequentially penetrates through the objective lens, the tube lens and the second focusing lens group and is reflected to the third focusing lens group through the deflection reflector, and after the measuring reflected light penetrates through the third focusing lens group, measuring mark imaging is formed on the image acquisition device.
In any of the above technical solutions, optionally, the focusing optical imaging system further includes a hollow reflecting mirror disposed between the second focusing mirror group and the barrel mirror;
the center of the hollow reflector is provided with a through hole, and the edge of the hollow reflector is provided with a reflector;
the marking plate is provided with a reference marking hole; light rays penetrate through the reference mark hole and form reference incident light rays, the reference incident light rays sequentially penetrate through the first focusing lens group and the second focusing lens group, are reflected by the edge of the hollow reflector and penetrate through the second focusing lens group, and are reflected to the third focusing lens group through the deflection reflector, and the reference incident light rays form reference mark imaging on the image acquisition device after penetrating through the third focusing lens group;
after the measuring incident light penetrates through the second focusing mirror group, the measuring incident light penetrates through the through hole of the hollow reflector and then enters the cylindrical mirror; after the measuring reflected light penetrates through the cylindrical mirror, the measuring reflected light penetrates through the through hole of the hollow reflecting mirror and enters the second focusing mirror group.
In any of the above technical solutions, optionally, the measurement mark hole includes a plurality of measurement mark small holes, the reference mark hole includes a plurality of reference mark small holes, and a pattern formed by the plurality of measurement mark small holes is disposed inside the pattern formed by the plurality of reference mark small holes;
a plurality of the reference mark small holes are distributed in a square or round shape.
In any of the above technical solutions, optionally, the incident angle of the object to be measured, at which the measurement incident light is incident on the object plane board, is 4 ° -10 °;
and/or the image of the measuring mark on the image acquisition device is 2 times to 10 times of the image of the measuring mark hole on the mark plate.
In any of the above technical solutions, optionally, the incident angle of the object to be measured, at which the measurement incident light is incident on the object plane board, is 4 ° -6 °;
the imaging of the measuring mark on the image acquisition device is 3 times to 5 times of the imaging of the measuring mark hole on the marking plate.
In any of the above technical solutions, optionally, the image acquisition device employs a linear array CCD.
In any of the above technical solutions, optionally, the mark plate is a chrome-plated mark plate;
in any of the above technical solutions, optionally, the focusing optical imaging system further includes a driving device;
the driving device is connected with the object space plane plate to drive the object space plane plate to be close to or far away from the objective lens along the first optical axis direction.
In any of the above technical solutions, optionally, the focusing optical imaging system further includes a light source; the light source is arranged on one side of the mark plate, which is far away from the first focusing lens group;
optionally, the light source is a laser light source or an LED light source.
In any of the above technical solutions, optionally, a silicon wafer is placed on the object plane plate.
The invention has the following beneficial effects:
the automatic focusing system comprises a marking plate, a first focusing lens group, a second focusing lens group, a tube lens, an objective lens, a turning reflector, a third focusing lens group and an image acquisition device, wherein the tube lens and the objective lens belong to one part of an alignment imaging optical system, namely the automatic focusing system and the alignment imaging optical system share the light path of the tube lens and the light path of the objective lens, so that the focusing time can be reduced to a certain extent, and the focusing accuracy can be improved. Specifically, the focusing optical imaging system converts first optical axis direction measurement mark information of a measurement mark hole on a mark plate into second optical axis direction measurement mark information of an image acquisition device through a folding reflector; the measuring mark information can be amplified through the first focusing lens group, the second focusing lens group, the tube lens, the objective lens and the third focusing lens group, the distance in the optical axis direction between the objective lens and an object space plane plate for placing an object to be measured can be accurately positioned by combining image recognition of the image acquisition device, the object to be measured is greatly ensured to be always in the best focal plane position in the alignment imaging optical system, the focusing time is reduced to a certain extent, the focusing precision is improved, and the influence of focusing on the alignment precision of the object to be measured in the alignment imaging optical system can be reduced to the minimum.
In order to make the aforementioned and other objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic structural diagram of a focusing optical imaging system according to an embodiment of the present invention;
fig. 2 is another schematic structural diagram of a focusing optical imaging system according to an embodiment of the present invention.
Icon: 1-a marking plate; 2-a first focusing lens group; 3-a second focusing lens group; 4-a hollow mirror; 5-a cylindrical mirror; 6-objective lens; 7-object plane plate; 8-a turning mirror; 9-a third focusing lens group; 10-image acquisition device.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Some embodiments of the invention are described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.
Examples
The present embodiment provides a focusing optical imaging system; referring to fig. 1 and fig. 2, fig. 1 and fig. 2 are two schematic structural diagrams of the focusing optical imaging system provided in this embodiment, wherein fig. 2 is compared with the focusing optical imaging system shown in fig. 1, and a hollow mirror is added. In fig. 1 and 2, the measurement incident ray is shown by a solid line, the measurement reflected ray is shown by a dotted line, the reference incident ray is shown by a dotted line, and the direction of the arrow in the drawing is the direction in which the rays are transmitted.
The focusing optical imaging system provided by the embodiment is used for aligning an imaging optical system, and is particularly used for a silicon wafer aligning imaging optical system based on an image recognition technology.
Referring to fig. 1 and fig. 2, the focusing optical imaging system according to the present embodiment includes a marking plate 1, a first focusing lens group 2, a second focusing lens group 3, a barrel lens 5, an objective lens 6, and an object space plane plate 7 for placing an object to be measured, which are sequentially arranged at intervals along a first optical axis direction; alternatively, the object to be measured is, for example, a silicon wafer, that is, the object space plane plate 7 is placed with a silicon wafer. The object to be measured may also be other materials, such as other semiconductor materials. Alternatively, the object plane plate 7 is configured to be movable in the first optical axis direction to change the optical axis distance between the object plane plate 7 and the objective lens 6; for example, the focusing optical imaging system further includes a driving device; the driving device is connected to the object space plane plate 7 to drive the object space plane plate 7 to approach or depart from the objective lens 6 along the first optical axis direction, so as to change the optical axis distance between the object space plane plate 7 and the objective lens 6, and thus, the object to be measured on the object space plane plate 7 is at the optimal focal plane position in the alignment imaging optical system.
The focusing optical imaging system also comprises a third focusing lens group 9 and an image acquisition device 10 which are sequentially arranged along the direction of a second optical axis; the first optical axis direction is perpendicular or approximately perpendicular to the second optical axis direction.
A turning reflector 8 is arranged between the first focusing mirror group 2 and the second focusing mirror group 3; the turning mirror 8 is configured to reflect the light transmitted in the first optical axis direction to transmit in the second optical axis direction; that is, the direction of light path transmission is changed by the turning mirror 8, and the first optical axis direction measurement mark information of the measurement mark hole on the mark plate 1 is converted into the second optical axis direction measurement mark information of the image capturing device 10, for example, the flat axis measurement mark information is converted into the vertical axis measurement mark information.
The marking plate 1 is provided with a measuring marking hole; the light rays pass through the measurement mark holes of the mark plate 1 and form measurement incident light rays (the measurement incident light rays are shown by solid lines in fig. 1 and fig. 2), and the measurement incident light rays sequentially penetrate through the first focusing lens group 2, the second focusing lens group 3, the barrel lens 5 and the objective lens 6 and are incident to an object to be measured on the object plane plate 7 at a certain incident angle; the measurement incident light is reflected by an object to be measured on the object space plane plate 7 to form measurement reflection light (the measurement reflection light is shown by a dotted line in fig. 1 and fig. 2), the measurement reflection light sequentially penetrates through the objective lens 6, the tube lens 5 and the second focusing lens group 3 and is reflected to the third focusing lens group 9 through the deflecting reflector 8, and after the measurement reflection light penetrates through the third focusing lens group 9, measurement mark imaging is formed on the image acquisition device 10.
Optionally, light passing through the measurement mark holes of the marking plate 1 forms a magnified measurement mark image on the image capturing device 10. For example, the measurement marks on the image acquisition device 10 are imaged 2 times to 10 times the measurement mark holes on the marking plate 1, or other magnification. Optionally, the measurement marks on the image acquisition device 10 are imaged 3-5 times larger than the measurement mark holes on the marking plate 1. In the present embodiment, the first focusing lens group 2, the second focusing lens group 3, the upper barrel lens 5, the objective lens 6 and the third focusing lens group 9 can magnify the optical axis measurement mark information, for example, by 3 times, 4 times, 8 times or other times.
In the focusing optical imaging system in this embodiment, the mark plate 1, the first focusing lens group 2, the second focusing lens group 3, the tube lens 5, the objective lens 6, the turning mirror 8, the third focusing lens group 9, and the image acquisition device 10 form an automatic focusing system, wherein the tube lens 5 and the objective lens 6 belong to a part of an alignment imaging optical system, that is, the automatic focusing system and the alignment imaging optical system share the optical paths of the tube lens 5 and the objective lens 6, which can reduce focusing time and improve focusing accuracy to a certain extent. Specifically, the focusing optical imaging system converts first optical axis direction measurement mark information of a measurement mark hole on the mark plate 1 into second optical axis direction measurement mark information of the image acquisition device 10 through the folding mirror 8; the measuring mark information can be amplified through the first focusing lens group 2, the second focusing lens group 3, the tube lens 5, the objective lens 6 and the third focusing lens group 9, the distance in the optical axis direction between the objective lens 6 and the object space plane plate 7 for placing the object to be detected can be accurately positioned by combining the image recognition of the image acquisition device 10, the object to be detected is greatly ensured to be always in the best focal plane position in the alignment imaging optical system, the focusing time is reduced to a certain extent, the focusing precision is improved, and the influence of the focusing on the alignment precision of the object to be detected in the alignment imaging optical system can be reduced to the minimum.
Referring to fig. 2, in an alternative of the present embodiment, the focusing optical imaging system further includes a hollow mirror 4 disposed between the second focusing mirror group 3 and the barrel mirror 5.
The center of the hollow reflector 4 is provided with a through hole, and the edge of the hollow reflector 4 is a reflector; i.e. the through-hole of the hollow reflector 4 is used for passing light and the edge of the hollow reflector 4 is used for reflecting light. It will be appreciated that the through hole of the hollow mirror 4 is used to pass through the measurement mark light, the edge of the hollow mirror 4 is used to reflect the reference mark light, and the reference mark and the measurement mark can be combined to determine defocus quickly and accurately.
Specifically, the marking plate 1 is provided with a reference mark hole; the light passes through the reference mark hole of the mark plate 1 and forms a reference incident light (shown by a dot-dash line in fig. 2), the reference incident light sequentially passes through the first focusing lens group 2 and the second focusing lens group 3, is reflected by the edge of the hollow reflector 4 and passes through the second focusing lens group 3, and is reflected to the third focusing lens group 9 by the turning reflector 8, and the reference incident light forms a reference mark image on the image acquisition device 10 after passing through the third focusing lens group 9.
Measuring incident light rays which penetrate through the second focusing lens group 3 and then penetrate through a through hole of the hollow reflector 4 to enter the tube mirror 5; after the measurement reflected light passes through the tube mirror 5, the measurement reflected light passes through the through hole of the hollow reflector 4 and enters the second focusing mirror group 3. That is, light passes through the measurement mark hole of the mark plate 1 and forms measurement incident light (the measurement incident light is shown by a solid line in fig. 2), the measurement incident light sequentially passes through the first focusing lens group 2 and the second focusing lens group 3, passes through the through hole of the hollow reflector 4 and enters the barrel lens 5, and passes through the objective lens 6 and enters the object to be measured on the object plane plate 7 at a certain incident angle; the measurement incident light is reflected by an object to be measured on the object space plane plate 7 to form measurement reflected light (the measurement reflected light is shown by a dotted line in fig. 2), the measurement reflected light sequentially penetrates through the objective lens 6 and the barrel mirror 5, penetrates through a through hole of the hollow reflector 4 and enters the second focusing lens group 3, is reflected to the third focusing lens group 9 through the turning reflector 8, and after the measurement reflected light penetrates through the third focusing lens group 9, measurement mark imaging is formed on the image acquisition device 10.
Optionally, light passing through the reference mark hole of the marking plate 1 forms a magnified reference mark image on the image capture device 10. For example, the reference mark on the image capture device 10 is imaged 2-10 times the reference mark hole on the marking plate 1, or other magnification.
In this embodiment, the first focusing lens group 2 is used for converging the parallel light beams parallel to the first optical axis direction at the focus; the second focusing lens group 3 is used for readjusting off-axis light rays converged by the focus into parallel light beams with a certain angle, and the parallel light beams are favorably reflected back to the image acquisition device 10 through the edge of the hollow reflector 4; the function of the tube lens 5 and the objective lens 6 is to provide a sufficient angle of view to ensure that symmetrical light beams can pass after being specularly reflected by the object plane plate 7; the third focusing lens group 9 is used to change the light from the deflecting mirror 8 into parallel light to be incident on the image capturing device 10 for the purpose of imaging the mark.
In the focusing optical imaging system of the embodiment, a reference mark image can be formed on the image acquisition device 10 through the hollow reflector 4 and the reference mark hole on the mark plate 1; namely, the imaging on the image acquisition device 10 is divided into two parts, one part is the imaging of the reference mark, the other part is the imaging of the measurement mark, the defocusing condition of the object to be measured is determined by measuring the relative position change of the imaging of the reference mark and the imaging of the measurement mark when the object to be measured is defocused, and then the object space plane plate 7 is driven to move to complete the automatic focusing work.
In the focusing optical imaging system of the present embodiment, the first focusing lens group 2, the second focusing lens group 3, the tube lens 5, and the objective lens 6 are original imaging optical path portions, on the basis of not changing the original light path, a hollow reflector 4 and a turning reflector 8 are added to convert the first optical axis direction information of the system to be measured into the second optical axis direction information on an image acquisition device 10, meanwhile, the device has certain magnification, and the distance in the optical axis direction between the objective lens 6 and the object space plane plate 7 for placing the object to be detected can be accurately positioned by combining the image recognition of the image acquisition device 10, so that the object to be detected is always in the optimal focal plane position in the alignment imaging optical system, the focusing time is reduced to a certain extent, the focusing precision is improved, and the influence of the off-focus on the alignment precision of the object to be detected to the imaging optical system can be reduced to the minimum.
Compared with the prior art, the focusing optical imaging system has the following advantages:
1. the relatively sensitive contrast difference when not depending on the defocusing of a shorter distance can obtain a larger focusing range.
2. The method has better linearity of the focusing system, and can keep better linearity in a longer focusing range.
3. Only one hollow reflector 4 and one turning reflector 8 are added, and the rest lens parts are all coaxial with the actual alignment imaging optical system.
4. The automatic focusing system and the alignment imaging optical system are designed in the same optical axis, are not limited by factors such as the distance between the objective lens 6 and the object space plane plate 7 for placing the object to be measured, the space size and the like, and have wider space applicability.
In this embodiment, in the focusing optical imaging system shown in fig. 1, the autofocus system and the alignment imaging optical system are designed on the same optical axis, and the focusing position can be determined by calculating the relationship between the measurement mark imaging and the reference origin of the image capturing device 10. But the alignment accuracy is slightly worse than the solution with reference marks. The focusing optical imaging system shown in fig. 2 determines the out-of-focus condition of the object to be measured by measuring the relative position change of the reference mark imaging and the measurement mark imaging when the object to be measured is out of focus by adopting the hollow reflector 4 and the reference mark hole on the mark plate 1, and then drives the object space plane plate 7 to move to finish the automatic focusing work, thereby further improving the focusing precision.
In an alternative of this embodiment, the measurement indicia bores comprise a plurality of measurement indicia bores.
In an alternative of this embodiment, the reference mark aperture comprises a plurality of reference mark apertures.
Optionally, a pattern formed by the plurality of measurement mark apertures is disposed inside a pattern formed by the plurality of reference mark apertures; to facilitate the contrast of the reference mark imaging and the measurement mark imaging.
Alternatively, the plurality of reference mark apertures are distributed in a square or circular pattern, or in other patterns.
Referring to fig. 1 and 2, in an alternative of the present embodiment, the incident angle of the object to be measured, at which the incident light is incident on the object plane plate 7, is measured to be 4 ° -10 °; for example, the incident angle of the object to be measured at which the incident light is incident on the object plane plate 7 is measured to be 4 °, 5 °, 7 °, or 8 °. For example, the object to be measured is measured when the incident light is incident on the object plane plate 7 at positive 5 °, and the object to be measured is reflected at negative 5 °.
Optionally, the incident angle of the object to be measured, at which the incident light is incident on the object plane plate 7, is measured to be 4 ° to 6 °.
In an alternative of this embodiment, the image capturing device 10 employs a linear array CCD. The CCD is an abbreviation of Charge Coupled Device, and is called a Charge Coupled Device in chinese. The linear array CCD has simple structure and lower cost, and the measuring range can be enlarged on the premise of the same measuring precision.
In an alternative of this embodiment, the marking plate 1 is a chrome-plated marking plate, or other marking plate.
In an alternative of this embodiment, the focusing optical imaging system further comprises a light source. The light source is arranged on one side of the mark plate 1 far away from the first focusing lens group 2.
Optionally, the light source is a laser light source or an LED light source, or other light sources.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A focusing optical imaging system is characterized by comprising a marking plate (1), a first focusing lens group (2), a second focusing lens group (3), a barrel lens (5), an objective lens (6) and an object space plane plate (7) for placing an object to be measured, wherein the marking plate, the first focusing lens group, the second focusing lens group, the barrel lens (5) and the objective lens (6) are sequentially arranged at intervals along a first optical axis direction; the object side plane plate (7) is configured to be movable in a first optical axis direction to change an optical axis distance between the object side plane plate (7) and the objective lens (6);
the focusing optical imaging system also comprises a third focusing lens group (9) and an image acquisition device (10) which are sequentially arranged along the direction of a second optical axis; the first optical axis direction is perpendicular to the second optical axis direction;
a turning reflector (8) is arranged between the first focusing mirror group (2) and the second focusing mirror group (3); the turning mirror (8) is configured to reflect the light transmitted along the first optical axis direction to transmit along the second optical axis direction;
the marking plate (1) is provided with a measuring marking hole; light rays penetrate through the measuring mark holes to form measuring incident light rays, and the measuring incident light rays sequentially penetrate through the first focusing lens group (2), the second focusing lens group (3), the tube lens (5) and the objective lens (6) and are incident to an object to be measured on the object space plane plate (7) at a certain incident angle; the measuring incident light beam passes through the object to be measured on the object space plane plate (7) is reflected to form measuring reflected light beam, the measuring reflected light beam sequentially penetrates through the objective lens (6), the tube lens (5) and the second focusing mirror group (3), and the measuring reflected light beam penetrates through the third focusing mirror group (9) and then is reflected to the third focusing mirror group (9) to form measuring mark imaging on the image acquisition device (10).
2. The focusing optical imaging system according to claim 1, further comprising a hollow mirror (4) disposed between the second focusing mirror group (3) and the barrel mirror (5);
the center of the hollow reflector (4) is provided with a through hole, and the edge of the hollow reflector (4) is a reflector;
the marking plate (1) is provided with a reference marking hole; light rays penetrate through the reference mark holes to form reference incident light rays, the reference incident light rays sequentially penetrate through the first focusing mirror group (2) and the second focusing mirror group (3), are reflected by the edge of the hollow reflector (4), penetrate through the second focusing mirror group (3), and are reflected to the third focusing mirror group (9) through the turning reflector (8), and reference mark imaging is formed on the image acquisition device (10) after the reference incident light rays penetrate through the third focusing mirror group (9);
after the measuring incident light penetrates through the second focusing lens group (3), the measuring incident light penetrates through a through hole of the hollow reflector (4) and enters the cylindrical lens (5); and after the measuring reflected light passes through the tube mirror (5), the measuring reflected light passes through the through hole of the hollow reflector (4) and enters the second focusing lens group (3).
3. The focusing optical imaging system of claim 2, wherein the measurement mark aperture comprises a plurality of measurement mark apertures, the reference mark aperture comprises a plurality of reference mark apertures, a pattern formed by the plurality of measurement mark apertures being disposed within the pattern formed by the plurality of reference mark apertures;
a plurality of the reference mark small holes are distributed in a square or round shape.
4. A focusing optical imaging system according to any of claims 1-3, characterized in that the angle of incidence of the measuring incident ray onto the object to be measured on the object plane plate (7) is 4 ° -10 °;
and/or the measuring mark on the image acquisition device (10) is imaged 2 times to 10 times of the measuring mark hole on the mark plate (1).
5. The focusing optical imaging system according to claim 4, characterized in that the angle of incidence of the measuring incident ray onto the object to be measured on the object plane plate (7) is 4 ° -6 °;
the imaging of the measuring mark on the image acquisition device (10) is 3-5 times of that of the measuring mark hole on the mark plate (1).
6. A focusing optical imaging system according to any of claims 1-3, characterized in that the image acquisition device (10) employs a line CCD.
7. The focusing optical imaging system according to any of claims 1 to 3, characterized in that the marking plate (1) is a chrome-plated marking plate.
8. The focusing optical imaging system of any of claims 1-3, further comprising a drive device;
the driving device is connected with the object space plane plate (7) so as to drive the object space plane plate (7) to be close to or far away from the objective lens (6) along the first optical axis direction.
9. The focusing optical imaging system of any of claims 1-3, further comprising a light source; the light source is arranged on one side of the mark plate (1) far away from the first focusing lens group (2);
optionally, the light source is a laser light source or an LED light source.
10. A focusing optical imaging system according to any of claims 1-3, characterized in that a silicon wafer is placed on the object plane plate (7).
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| CN114415325B (en) | 2023-11-03 |
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