A method for adjusting a testing device

Abstract

This application provides a method for adjusting a detection device. The detection device, from the object side to the image side, includes an objective lens, a beam splitter, a telescope, and a detector, and also includes a Kohler illumination module. An illumination beam is emitted from the Kohler illumination module, transmitted through the beam splitter to the objective lens. When the object to be tested is placed on the side of the objective lens away from the beam splitter, a reflected beam is obtained by reflecting the illumination beam emitted from the objective lens. The reflected beam passes sequentially through the objective lens, beam splitter, and telescope to the detector. After inserting an aperture stop in the Kohler illumination module and placing a first auxiliary lens between the telescope and the beam splitter, the detector obtains the first spot position of the light spot formed by the aperture stop at the entrance pupil of the objective lens. When the Kohler illumination module does not provide an illumination beam and the light source is used as the object to be tested, the detector obtains the second spot position of the light spot at the entrance pupil of the objective lens. The position of the aperture stop is adjusted according to the first and second spot positions to align the illumination optical axis and the imaging optical axis.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microscopic imaging, in particular to an adjusting method of a detection device. BACKGROUND

[0002] In the process of semiconductor manufacturing, it is often necessary to use a detection device to detect a to-be-detected object, such as a to-be-detected wafer. The detection device usually includes a Kohler illumination module as an illumination system to illuminate an imaging system in the detection device. In order to obtain a better imaging effect, the optical axis of the Kohler illumination module and the imaging system need to be aligned. In the process of detecting the to-be-detected object, the aperture stop in the Kohler illumination module needs to be switched. Different aperture stops have different sizes, thereby producing different illumination numerical apertures (NA). Different aperture stops are used to cope with the measurement of different to-be-detected objects. In the switching process of the aperture stop, the optical axis of the inserted aperture stop needs to be aligned with the original optical axis, so that the illumination optical axis passing through the aperture stop is aligned with the imaging optical axis. The current alignment method is low in efficiency and complicated in operation. SUMMARY

[0003] Therefore, the purpose of the present application is to provide an adjusting method of a detection device, which can quickly realize the alignment of the illumination optical axis and the imaging optical axis and is simple in operation. The specific scheme is as follows:

[0004] In one aspect, the present application provides an adjusting method of a detection device. The detection device includes, in order from the object side to the image side, an objective lens, a beam splitter, a tube lens, and a detector. The detection device also includes a Kohler illumination module. An illumination beam is emitted from the Kohler illumination module, transmitted through the beam splitter, and reaches the objective lens. When a to-be-detected object is arranged on the side of the objective lens away from the beam splitter, the objective lens reflects the illumination beam emitted therefrom to obtain a reflected beam. The reflected beam passes through the objective lens, the beam splitter, and the tube lens in order and reaches the detector. The method includes the following steps:

[0005] After an aperture stop is inserted into the Kohler illumination module and a first auxiliary lens is arranged between the beam splitter and the tube lens, a first light spot position of a light spot formed by the aperture stop at an entrance pupil of the objective lens is acquired by the detector. The first auxiliary lens makes the entrance pupil and an image plane of the detector conjugate.

[0006] When the Kohler illumination module does not provide an illumination beam and a surface light source is used as the to-be-detected object, a second light spot position of a light spot at the entrance pupil of the objective lens is acquired by the detector.

[0007] The position of the aperture stop is finely adjusted according to the first light spot position and the second light spot position, so that the centers of the light spots at the first light spot position and the second light spot position tend to coincide.

[0008] Optionally, before the position of the aperture diaphragm is fine-adjusted according to the first light spot position and the second light spot position, the method further comprises:

[0009] After the aperture diaphragm is inserted into the Kohler illumination module, and a second auxiliary lens is arranged between the barrel lens and the detector, a third light spot position of a light spot formed by the aperture diaphragm at the entrance pupil of the objective lens is acquired by the detector; the second auxiliary lens makes the entrance pupil and an image plane of the detector conjugate;

[0010] When the Kohler illumination module does not provide an illumination beam, and a surface light source is used as the object to be measured, a fourth light spot position of a light spot at the entrance pupil of the objective lens is acquired by the detector;

[0011] The position of the aperture diaphragm is coarsely adjusted according to the third light spot position and the fourth light spot position, so that the centers of the light spots of the third light spot position and the fourth light spot position tend to coincide;

[0012] The second auxiliary lens is removed.

[0013] Optionally, the first auxiliary lens is a focusing lens and the second auxiliary lens is a focusing lens.

[0014] Optionally, the focal length of the second auxiliary lens is 45 mm, the distance between the second auxiliary lens and the barrel lens is 43.98 mm, and the distance between the second auxiliary lens and the image plane of the detector is 60.07 mm; the focal length of the first auxiliary lens is 90 mm, the distance between the first auxiliary lens and the entrance pupil of the objective lens is 95.17 mm, and the distance between the first auxiliary lens and the barrel lens is 19.17 mm; the distance between the barrel lens and the image plane of the detector is 109.04 mm, the focal length of the objective lens is 2 mm, and the focal length of the barrel lens is 200 mm.

[0015] Optionally, the position of the aperture diaphragm is adjusted according to the first light spot position and the second light spot position, comprising:

[0016] A light spot center offset parameter of the first light spot position relative to the second light spot position is acquired;

[0017] According to the light spot center offset parameter, the position of the aperture diaphragm is adjusted in a direction perpendicular to the optical axis.

[0018] Optionally, the first light spot position is determined by a first light spot image generated by the detector, and the second light spot position is determined by a second light spot image generated by the detector.

[0019] Optionally, the acquiring the spot center offset parameter of the first spot position relative to the second spot position comprises:

[0020] determining the first spot position according to a first pixel position of a spot center in the first spot image;

[0021] determining the second spot position according to a second pixel position of a spot center in the second spot image;

[0022] determining the spot center offset parameter of the first spot position relative to the second spot position according to a magnification of the detector and a pixel offset parameter between the first spot position and the second spot position.

[0023] Optionally, the detection device further comprises an optical fiber for guiding the illumination light beam to the Kohler illumination module, and the method further comprises:

[0024] removing the illumination light beam in the optical fiber or removing the optical fiber to cancel the illumination light beam into the Kohler illumination module.

[0025] Optionally, the method further comprises:

[0026] canceling the first auxiliary lens, restoring the illumination light beam into the Kohler illumination module, setting the object to be detected on a side of the objective lens away from the beam splitter, and detecting the reflected light beam from the object to be detected by the detector to realize detection of the object to be detected.

[0027] Optionally, a surface to be detected of the object to be detected is arranged on a focal plane of the objective lens, and the focal plane is conjugate to an image plane of the detector.

[0028] Optionally, the Kohler illumination module comprises a first lens, a second lens and a third lens arranged in sequence, the illumination light beam is converted into parallel light by the first lens, the aperture stop is located between the second lens and the third lens and at a focal point of the second lens, the second lens and the third lens are focusing lenses, and the third lens is used to focus the illumination light beam into an entrance pupil of the objective lens in combination with the beam splitter.

[0029] The embodiment of the present application provides a kind of detection equipment adjustment method, detection equipment is successively included objective lens, beam splitter, barrel lens and detector from object side to image side, also include Kohler illumination module;Illumination beam is emitted from Kohler illumination module, is transmitted to objective lens by beam splitter, when the object to be measured is set in the side of objective lens away from beam splitter, for the reflection of the illumination beam emitted in objective lens is obtained reflected light beam, reflected light beam is successively through objective lens, beam splitter and barrel lens reaches detector.In Kohler illumination module inserts aperture diaphragm, and after being provided with first auxiliary lens between beam splitter and barrel lens, the first light spot position of the light spot that aperture diaphragm forms in the entrance pupil of objective lens is acquired by detector;First auxiliary lens makes the entrance pupil and the image plane of detector conjugate, since aperture diaphragm and the entrance pupil of objective lens are conjugate, therefore aperture diaphragm and the image plane of detector are also conjugate, and the light spot position of aperture diaphragm can be acquired by detector, and detection equipment constitutes the imaging system of magnification, so the light spot at image plane is larger than the light spot at the entrance pupil of objective lens, so the determination of light spot position is more accurate;In the case where Kohler illumination module does not provide illumination beam and light source is used as the object to be measured, the second light spot position of the light spot of the entrance pupil of objective lens is acquired by detector, and the determination of second light spot position obtained based on the imaging system of magnification is also more accurate;The first light spot position can also reflect the light spot position of aperture diaphragm in the entrance pupil of objective lens, and the second light spot position reflects the light spot position of the entrance pupil itself, so the relative position of the two reflects the relative position of illumination optical axis and imaging optical axis, and the position of aperture diaphragm is adjusted according to the first light spot position and the second light spot position, so that the light spot centers of the first light spot position and the second light spot position tend to coincide, so the operation is targeted, and the illumination optical axis and the imaging optical axis can be quickly aligned, the operation is simple, and in the case where the determination of the first light spot position and the second light spot position is more accurate, the alignment accuracy of the illumination optical axis and the imaging optical axis is also higher. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0031] Figure 1 A structure schematic diagram of a detection equipment provided by the embodiment of the present application is shown;

[0032] Figure 2 A flowchart of the adjustment method of the detection equipment provided by the embodiment of the present application is shown;

[0033] Figure 3 An imaging process schematic diagram provided by the embodiment of the present application is shown;

[0034] Figure 4 Another imaging process schematic diagram provided by the embodiment of the present application is shown;

[0035] Figure 5 Another imaging process schematic diagram provided by the embodiment of the present application is shown;

[0036] Figure 6 Another imaging process schematic diagram provided by the embodiment of the present application is shown. DETAILED DESCRIPTION

[0037] In order to make the above objectives, characteristics and advantages of the present application more apparent, comprehensible and easier to understand, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0038] In the following description, a lot of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other different ways from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.

[0039] Secondly, the present application is described in detail in combination with the schematic diagram, in the detailed description of the embodiments of the present application, for the convenience of description, the cross-sectional view of the device structure will be partially enlarged without the general proportion, and the schematic diagram is only an example, which should not limit the scope of protection of the present application herein. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in the actual manufacture.

[0040] As described in the background, in the switching process of the aperture stop, it is necessary to ensure that the optical axis of the inserted aperture stop is aligned with the original optical axis, so that the illumination optical axis passing through the aperture stop is aligned with the imaging optical axis. At present, laser triangulation can be used, that is, laser is input from the Kohler illumination module, the laser is incident to the objective lens after passing through the Kohler illumination module, a mirror is arranged on the focal plane of the objective lens, the laser returns to the objective lens through the mirror, and then is imaged on the camera after passing through the barrel lens. By defocusing the mirror, the center change of the light spot on the camera is observed, and then the position of the aperture stop is adjusted, so as to adjust the eccentricity of illumination and imaging. However, this way is low in efficiency and complex in operation.

[0041] To solve the above technical problems, the embodiment of the present application provides an adjusting method of a detection device, the detection device comprises, in sequence from an object side to an image side, an objective lens, a beam splitter, a tube lens and a detector, and further comprises a Kohler illumination module; an illumination beam is emitted from the Kohler illumination module, transmitted through the beam splitter to the objective lens, and when an object to be detected is arranged on a side of the objective lens away from the beam splitter, the objective lens is used to reflect the illumination beam emitted from the objective lens to obtain a reflected beam, and the reflected beam is sequentially transmitted through the objective lens, the beam splitter and the tube lens to the detector. After an aperture stop is inserted into the Kohler illumination module and a first auxiliary lens is arranged between the beam splitter and the tube lens, a first light spot position of a light spot formed by the aperture stop at an entrance pupil of the objective lens is acquired by the detector; the first auxiliary lens makes the entrance pupil and an image plane of the detector conjugate, the aperture stop and the image plane of the detector are conjugate because the aperture stop and the entrance pupil of the objective lens are conjugate, the light spot position of the aperture stop can be acquired by the detector, and the detection device forms an imaging system with a magnification, so that the light spot at the image plane is larger than the light spot at the entrance pupil of the objective lens, and thus the determination of the light spot position is more accurate; in the case that the Kohler illumination module does not provide the illumination beam and a light source is used as the object to be detected, a second light spot position of a light spot of the entrance pupil of the objective lens is acquired by the detector, and the determination of the second light spot position based on the imaging system with the magnification is also more accurate; the first light spot position can also represent the light spot position of the aperture stop at the entrance pupil of the objective lens, and the second light spot position represents the light spot position of the entrance pupil itself, so that the relative positions of the two represent the relative positions of an illumination optical axis and an imaging optical axis, and the positions of the aperture stop are adjusted according to the first light spot position and the second light spot position, so that the centers of the light spots of the first light spot position and the second light spot position tend to coincide, so that the operation is targeted and can quickly align the illumination optical axis and the imaging optical axis, the operation is simple, and in the case that the determination of the first light spot position and the second light spot position is more accurate, the alignment accuracy of the illumination optical axis and the imaging optical axis is also higher.

[0042] To facilitate understanding, the adjusting method of the detection device provided by the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0043] Reference Figure 1 As shown in FIG. 1, which is a structural schematic diagram of a detection device provided by the embodiment of the present application, the detection device comprises, in sequence from an image side to an object side, an objective lens 11, a beam splitter 12, a tube lens 13 and a detector 14, and further comprises a Kohler illumination module 15.

[0044] The Kohler illumination module 15 is used to provide uniform and sufficient bright illumination, and the Kohler illumination module 15 can include a first lens 151, a second lens 152 and a third lens 153 arranged in sequence. The illumination beam irradiated into the Kohler illumination module 15 is converted into parallel light by the first lens 151. The second lens 152 and the third lens 153 are focusing lenses. After the parallel light passes through the second lens 152, the parallel light is focused to the focal point position of the second lens 152 to form divergent light incident on the third lens 153. The third lens 153 focuses the divergent light to obtain a focused light beam incident on the beam splitter 12 to illuminate the imaging system. That is, the illumination beam is emitted from the Kohler illumination module 15 to illuminate the imaging system. The illumination beam can be visible light, such as white light, etc.

[0045] The detection device can further include an optical fiber 16 for guiding the illumination beam to the Kohler illumination module 15. An outcoupling port of the optical fiber 16 can be located at the focal point position of the first lens 151, so that the first lens 151 can convert the illumination beam into parallel light.

[0046] The imaging system can include an objective lens 11, a beam splitter 12, a tube lens 13 and a detector 14. After the illumination beam passes through the beam splitter 12, it can be transmitted to the objective lens 11 after being reflected by the beam splitter 12. When the object 20 to be detected is arranged on the side of the objective lens 11 away from the beam splitter 12, the illumination beam emitted from the objective lens 11 can be reflected to obtain a reflected beam, and the reflected beam can reflect the topography of the object 20 to be detected. The reflected beam then passes through the objective lens 11, the beam splitter 12 and the tube lens 13 in sequence to reach the detector 14. The detector 14 captures the reflected beam to realize detection of the object 20 to be detected. The tube lens 13 is used to cooperate with the objective lens 11 to image the object 20 to be detected on the focal plane of the objective lens 11. The third lens 153 can focus the illumination beam on the entrance pupil 111 of the objective lens 11 in combination with the beam splitter 12. In this way, the illumination beam can be diverged by the objective lens 11 to uniformly illuminate the detection surface of the object 20 to be detected.

[0047] When detecting the object 20 to be detected, the detection surface of the object 20 to be detected can be located on the focal plane of the objective lens 11. The focal plane of the objective lens 11 is conjugate with the image plane 141 of the detector 14 to obtain a clear image of the detection surface. As an example, the focal length of the objective lens 11 can be 2 mm, the focal length of the tube lens 13 can be 200 mm, and the distance between the tube lens 13 and the image plane 141 of the detector 14 can be 109.04 mm, so that the detection of the object 20 to be detected is realized based on the detection device.

[0048] Reference Figure 2 As shown in the figure, a flowchart of an adjusting method of a detection device provided by an embodiment of the present application can include the following steps:

[0049] S101, after inserting the aperture stop 17 in the Kohler illumination module 15 and setting the first auxiliary lens 181 between the beam splitter 12 and the barrel lens 13, acquiring, by the detector 14, a first light spot position of a light spot formed by the aperture stop 17 at the entrance pupil 111 of the objective lens 11; the first auxiliary lens 181 makes the entrance pupil 111 and the image plane 141 of the detector 14 conjugate.

[0050] In the embodiment of the present application, the aperture stop 17 can be inserted in the Kohler illumination module 15, the aperture stop 17 is used to limit the imaging light beam, different numerical apertures can be generated by the aperture stop 17, so as to cope with the measurement of different objects to be measured 20, the aperture stop 17 can be provided with a single aperture or an aperture array formed by multiple apertures, and the shape of the aperture is a circular hole or a rectangular hole.

[0051] Since the pupil plane of the illumination system and the focal plane of the objective lens 11 are conjugate in the Kohler illumination module 15, when the aperture stop 17 is set at the pupil plane of the illumination system, the camera will observe the shape of the aperture stop 17. Specifically, the aperture stop 17 can be located between the second lens 152 and the third lens 153, and at the focal point of the second lens 152, the plane of the vertical optical axis where the focal point of the second lens 152 is located is the focal plane, which is the pupil plane of the Kohler illumination module 15.

[0052] Since the aperture stop 17 of the Kohler illumination and the entrance pupil 111 of the objective lens 11 are conjugate, whether the center of the light spot of the aperture stop 17 at the entrance pupil 111 of the objective lens 11 is aligned with the center of the entrance pupil 111 can be used to judge whether the position of the aperture stop 17 is accurate, that is, whether the optical axis of the aperture stop 17 is aligned with the optical axis of the imaging system. However, since the image plane 141 of the detector 14 and the mirror plane of the objective lens 11 are conjugate, the barrel lens 13 alone cannot image the entrance pupil 111 of the objective lens 11.

[0053] In the embodiment of the present application, the first auxiliary lens 181 can be set between the beam splitter 12 and the barrel lens 13, the first auxiliary lens 181 makes the entrance pupil 111 of the objective lens 11 and the image plane 141 of the detector 14 conjugate, so that the entrance pupil 111 of the objective lens 11 can be observed. The first auxiliary lens 181 is a focusing lens, which can be a doublet lens, the entrance pupil 111 of the objective lens 11 is a plane perpendicular to the optical axis, which can also be referred to as an entrance pupil plane. The parameters of the first auxiliary lens 181 can be obtained by simulation, as an example, the focal length of the first auxiliary lens 181 is 90 mm, the distance between the first auxiliary lens 181 and the entrance pupil 111 of the objective lens 11 is 95.17 mm, and the distance between the first auxiliary lens 181 and the barrel lens 13 is 19.17 mm.

[0054] Thus, after the aperture stop 17 is inserted in the Kohler illumination module 15 and the first auxiliary lens 181 is arranged between the barrel lens 13 and the beam splitter 12, the first spot position of the spot formed by the aperture stop 17 at the entrance pupil 111 of the objective lens 11 is acquired by the detector 14, as shown in the reference Figure 3 Fig. 1, which is a schematic diagram of an imaging process provided by an embodiment of the present application. The illumination beam emitted by the Kohler illumination module 15 is focused into a spot at the entrance pupil 111 of the objective lens 11, and the detector 14 detects the spot to obtain the first spot position.

[0055] The first spot position can be determined according to a first pixel position of the center of the spot in the first spot image generated by the detector. The first pixel position is, for example, a pixel position of a pixel center point at which the center of the spot is located, or a pixel position of the center of the spot. For example, the first pixel position can be taken as the first spot position.

[0056] After the first auxiliary lens 181 is arranged between the barrel lens 13 and the beam splitter 12, the imaging system from the entrance pupil of the objective lens to the image plane of the detector has a magnification. At this time, the spot at the image plane is larger than the spot at the entrance pupil of the objective lens, and the spot range at the image plane is large and occupies a large pixel area. Therefore, the determination of the first spot position is more accurate, and the first spot position has a high sensitivity to the change in the position of the aperture stop.

[0057] S102, in the case where the Kohler illumination module 15 does not provide an illumination beam and the area light source 19 is taken as the object to be measured 20, the second spot position of the spot at the entrance pupil 111 of the objective lens 11 is acquired by the detector 14.

[0058] When the Kohler illumination module 15 does not provide an illumination beam and the first auxiliary lens 181 is retained, the aperture stop 17 is removed from the spot at the entrance pupil 111 of the objective lens 11. At this time, the imaging of the spot at the entrance pupil 111 can be performed. In the case where the area light source 19 is taken as the object to be measured, the second spot position of the spot at the entrance pupil 111 of the objective lens 11 is acquired by the detector 14, as shown in the reference Figure 4 Fig. 2, which is another schematic diagram of an imaging process provided by an embodiment of the present application. The parallel light provided by the area light source 19 is focused into a spot at the entrance pupil 111 of the objective lens 11 under the action of the objective lens 11, and the detector 14 detects the spot to obtain the second spot position. Similarly, because the spot at the image plane is larger than the spot at the entrance pupil of the objective lens, the determination of the second spot position is also more accurate.

[0059] The second light spot position can be determined according to a second light spot image generated by the detector, and the second light spot image can include a light spot of the entrance pupil 111 of the objective lens 11. The second light spot position can be determined according to a second pixel position of a light spot center in the second light spot image, for example, a pixel position of a pixel center point at which the light spot center is located, or a pixel position of the light spot center. The second pixel position can be taken as the second light spot position.

[0060] In a specific implementation, the illumination beam entering the Kohler illumination module 15 can be removed by removing the illumination beam in the optical fiber 16 or by removing the optical fiber 16, so that the Kohler illumination module 15 does not provide the illumination beam. The area light source can be disposed at a focal plane of the objective lens 11.

[0061] In S103, the position of the aperture diaphragm 17 is finely adjusted according to the first light spot position and the second light spot position, so that the light spot centers of the first light spot position and the second light spot position tend to coincide.

[0062] According to the foregoing description, the first light spot position can be obtained by illuminating the entrance pupil 111 of the objective lens 11 with the illumination beam emitted by the Kohler illumination module 15 and imaging the illuminated entrance pupil 111 on the detector 14 to obtain a light spot of the Kohler illumination on the entrance pupil 111 of the objective lens 11. Then, the second light spot position can be obtained by illuminating the entrance pupil 111 of the objective lens 11 with the area light source disposed on a side of the objective lens 11 away from the detector 14, and imaging the illuminated entrance pupil 111 on the detector 14 to obtain a light spot of the entrance pupil 111 of the objective lens 11. The first light spot position indicates the optical axis position of the aperture diaphragm 17, and the second light spot position indicates the optical axis position of the imaging system. The position of the aperture diaphragm 17 can be adjusted according to the first light spot position and the second light spot position, so that the light spot centers of the first light spot position and the second light spot position tend to coincide, and then the optical axis of the aperture diaphragm 17 is aligned with the optical axis of the imaging system, so that the optical axes of the illumination system and the imaging system are aligned. The speed is faster and the operation is simpler. In addition, when the first light spot position and the second light spot position are determined more accurately, the alignment precision of the illumination optical axis and the imaging optical axis is also higher.

[0063] Specifically, a light spot center offset parameter of the first light spot position relative to the second light spot position can be obtained, and the position of the aperture diaphragm 17 is adjusted in a direction perpendicular to the optical axis according to the light spot center offset parameter, so that the optical axis of the aperture diaphragm 17 is aligned with the optical axis of the imaging system. After the first light spot position and the second light spot position are determined, the light spot center offset parameter of the first light spot position relative to the second light spot position can be determined according to a magnification of the detector 14 and a pixel offset parameter between the first light spot position and the second light spot position. Generally, the light spot center offset parameter is equal to a ratio of the pixel offset parameter and the magnification.

[0064] The pixel offset parameter can be a product of a length of a single pixel and an integer. For example, if the first light spot position and the second light spot position are offset by 1 pixel, and the length of each pixel is 3.5 microns, the pixel offset parameter is 3.5 microns, and the ratio of the pixel offset parameter to the magnification is used as the light spot center offset parameter.

[0065] In summary, the first auxiliary lens 181 is arranged between the beam splitter 12 and the barrel lens 13, so that the object lens entrance pupil to the image plane of the detector forms a magnification imaging system. At this time, the light spot on the image plane is larger than the light spot of the object lens entrance pupil, the light spot range on the image plane is larger, and the pixel area occupied is also larger. The first light spot image and the second light spot image obtained are images of light spots after magnification. Therefore, the light spot center determined according to the pixels is more accurate, and the position change relative to the aperture diaphragm has higher sensitivity, and higher aperture diaphragm and imaging system optical axis alignment accuracy can be achieved. For example, when the pixel offset parameter is a product of the length of a single pixel and an integer, the larger the magnification, the more the number of pixels corresponding to the pixel offset parameter, the higher the accuracy, and the higher the accuracy of the determined light spot center offset parameter.

[0066] In addition, when the auxiliary lens is arranged between the barrel lens 13 and the detector 14, the object lens entrance pupil to the image plane of the detector forms a demagnification imaging system. At this time, the light spot on the image plane is smaller than the light spot of the object lens entrance pupil, the light spot range on the image plane is smaller, and the pixel area occupied is also smaller. The obtained image is an image of a light spot after demagnification. Therefore, the global information is easy to be observed, but the determination of the light spot center based on the pixels is easy to lead to inaccurate determination of the light spot center, which affects the aperture diaphragm and imaging system optical axis alignment accuracy.

[0067] Therefore, the adjustment of the aperture diaphragm 17 when the first auxiliary lens 181 is arranged between the beam splitter 12 and the barrel lens 13 can be used as fine adjustment, and the adjustment of the aperture diaphragm 17 when the second auxiliary lens 182 is arranged between the barrel lens 13 and the detector 14 can be used as coarse adjustment. Before fine adjustment of the aperture diaphragm 17, the aperture diaphragm 17 can be fine adjusted first, so as to avoid the problem of invalid fine adjustment caused by the failure to observe the global image of the light spot. That is, S201-S204 can also be performed before S101.

[0068] S201, after the aperture diaphragm 17 is inserted into the Kohler illumination module 15 and the second auxiliary lens 182 is arranged between the barrel lens 13 and the detector 14, the third light spot position of the light spot formed by the aperture diaphragm 17 at the entrance pupil 111 of the object lens 11 is obtained by the detector 14. The second auxiliary lens 182 makes the entrance pupil 111 and the image plane 141 of the detector 14 conjugate.

[0069] In the embodiment of the present application, a second auxiliary lens 182 can be arranged between the barrel lens 13 and the detector 14, the second auxiliary lens 182 can make the entrance pupil 111 of the objective lens 11 and the image plane 141 of the detector 14 conjugate, so that the entrance pupil 111 of the objective lens 11 can be observed. The second auxiliary lens 182 is a focusing lens, which can be a doublet lens. The entrance pupil 111 of the objective lens 11 is a plane perpendicular to the optical axis, which can also be referred to as an entrance pupil plane. The parameters of the second auxiliary lens 182 can be obtained by simulation. As an example, the focal length of the second auxiliary lens 182 is 45 mm, the distance between the second auxiliary lens 182 and the barrel lens is 43.98 mm, and the distance between the second auxiliary lens 182 and the image plane 141 of the detector 14 is 60.07 mm.

[0070] In this way, after the aperture stop 17 is inserted into the Kohler illumination module 15 and the second auxiliary lens 182 is arranged between the barrel lens 13 and the detector 14, the third spot position of the light spot formed by the aperture stop 17 in the entrance pupil 111 of the objective lens 11 can be obtained by the detector 14. Referring to FIG. 13, another imaging process schematic diagram provided by the embodiment of the present application is shown. The illumination beam emitted by the Kohler illumination module 15 is focused into a light spot in the entrance pupil 111 of the objective lens 11, and the detector 14 detects the light spot to obtain the third spot position. Figure 5

[0071] The third spot position can be determined by a third spot image generated by the detector. The third spot image can include the light spot formed by the aperture stop 17 in the entrance pupil 111 of the objective lens 11. The third spot position can be determined according to the third pixel position of the center of the light spot in the third spot image. The third pixel position can be, for example, the pixel position of the center point of the pixel where the center of the light spot is located, or the pixel position of the center of the light spot. For example, the third pixel position can be taken as the third spot position.

[0072] After the second auxiliary lens 182 is arranged between the barrel lens 13 and the detector 14, the entrance pupil of the objective lens to the image plane of the detector forms a reduced magnification imaging system. At this time, the light spot on the image plane is smaller than the light spot on the entrance pupil of the objective lens, the range of the light spot on the image plane is smaller, and the pixel area occupied by the light spot is also smaller. Therefore, the global characteristics of the light spot can be easily observed, and the problem of precision adjustment failure caused by the inability to observe the global image of the light spot can be avoided.

[0073] S202, in the case that the Kohler illumination module 15 does not provide an illumination beam and the area light source 19 is used as the object 20 to be measured, the fourth spot position of the light spot of the entrance pupil 111 of the objective lens 11 is obtained by the detector 14.

[0074] ​When the Kohler illumination module 15 does not provide the illumination light beam and the second auxiliary lens 182 is reserved, the light spot of the aperture stop 17 at the entrance pupil 111 of the objective lens 11 is removed, and the imaging of the light spot of the entrance pupil 111 can be performed at this time. When the area light source 19 is taken as the object to be measured, the fourth light spot position of the light spot of the entrance pupil 111 of the objective lens 11 can be obtained by the detector 14. Referring to Figure 6 Fig. 16 shows another imaging process provided by the embodiment of the present application. The parallel light provided by the area light source 19 is focused to the entrance pupil 111 of the objective lens 11 under the action of the objective lens 11 to form a light spot, and the detector 14 detects the light spot to obtain the fourth light spot position. Similarly, since the light spot of the image plane is larger than the light spot of the entrance pupil of the objective lens, the global characteristics of the light spot are easier to observe.

[0075] The fourth light spot position can be determined by a fourth light spot image generated by the detector. The fourth light spot image can include the light spot of the entrance pupil 111 of the objective lens 11. The fourth light spot position can be determined according to a fourth pixel position of the center of the light spot in the fourth light spot image. The fourth pixel position is, for example, a pixel position of a pixel center point at which the center of the light spot is located, or a pixel position of the center of the light spot. For example, the fourth pixel position can be taken as the fourth light spot position.

[0076] In a specific implementation, the illumination light beam in the optical fiber 16 can be removed, or the optical fiber 16 can be removed to cancel the illumination light beam entering the Kohler illumination module 15, so that the Kohler illumination module 15 does not provide the illumination light beam. The area light source can be arranged at the focal plane of the objective lens 11.

[0077] S203. Coarse adjustment is performed on the position of the aperture stop 17 according to the third light spot position and the fourth light spot position, so that the centers of the light spots of the third light spot position and the fourth light spot position tend to coincide.

[0078] According to the foregoing description, the illumination light beam emitted by the Kohler illumination module 15 can illuminate the entrance pupil 111 of the objective lens 11, the illuminated entrance pupil 111 is imaged on the detector 14 to obtain the light spot of the Kohler illumination on the entrance pupil 111 of the objective lens 11 to obtain the third light spot position. Then, the area light source is arranged on the side of the objective lens 11 away from the detector 14, so that the entrance pupil 111 of the objective lens 11 is illuminated by the area light source, and the illuminated entrance pupil 111 is imaged on the detector 14 to obtain the light spot of the entrance pupil 111 of the objective lens 11 to obtain the fourth light spot position. The third light spot position indicates the optical axis position of the aperture stop 17, and the fourth light spot position indicates the optical axis position of the imaging system. According to the third light spot position and the fourth light spot position, the position of the aperture stop 17 can be adjusted, so that the centers of the light spots of the third light spot position and the fourth light spot position tend to coincide, and then the optical axis of the aperture stop 17 is aligned with the optical axis of the imaging system, the optical axes of the illumination system and the imaging system are aligned, the speed is faster, and the operation is simple.

[0079] Specifically, the spot center offset parameter of the third spot position relative to the fourth spot position can be obtained, and the position of the aperture stop 17 is adjusted in the direction perpendicular to the optical axis according to the spot center offset parameter, so that the optical axis of the aperture stop 17 is aligned with the optical axis of the imaging system. After the third spot position and the fourth spot position are determined, the spot center offset parameter of the third spot position relative to the fourth spot position can be determined according to the magnification of the detector 14 and the pixel offset parameter between the third spot position and the fourth spot position. Generally, the spot center offset parameter is equal to the ratio of the pixel offset parameter and the magnification. The pixel offset parameter can be the product of the length of a single pixel and an integer.

[0080] S204, the second auxiliary lens 182 is removed.

[0081] After the coarse adjustment of the aperture stop 17, the second auxiliary lens 182 can be removed so that the first auxiliary lens 181 is inserted in S101 to achieve fine adjustment of the aperture stop 17.

[0082] After fine adjustment of the aperture stop 17, the first auxiliary lens 181 can be removed to restore the illumination beam entering the Kohler illumination module 15, set the to-be-measured object 20 on the side of the objective lens 11 away from the beam splitter 12, and detect the reflected beam from the to-be-measured object 20 by the detector 14 to achieve detection of the to-be-measured object 20. The to-be-measured object 20 can be a to-be-measured wafer.

[0083] The embodiment of the present application provides a kind of detection equipment adjustment method, detection equipment includes objective lens, beam splitter, barrel lens and detector in order from object side to image side, also includes Kohler illumination module;Illumination beam is emitted from Kohler illumination module, is transmitted to objective lens by beam splitter, when the object to be measured is set in the side of objective lens away from beam splitter, for the reflection of the illumination beam emitted in objective lens is obtained reflected light beam, reflected light beam is sequentially through objective lens, beam splitter and barrel lens to reach detector.In Kohler illumination module inserts aperture diaphragm, and after being provided with first auxiliary lens between barrel lens and beam splitter, the first light spot position of the light spot formed by aperture diaphragm in the entrance pupil of objective lens is acquired by detector;First auxiliary lens makes the entrance pupil and the image plane of detector conjugate, since aperture diaphragm and the entrance pupil of objective lens are conjugate, therefore aperture diaphragm and the image plane of detector are also conjugate, and the light spot position of aperture diaphragm can be acquired by detector, and detection equipment constitutes the imaging system of magnification, so the light spot at image plane is larger than the light spot at the entrance pupil of objective lens, so the determination of light spot position is more accurate;In the case that Kohler illumination module does not provide illumination beam and light source is used as the object to be measured, the second light spot position of the light spot of the entrance pupil of objective lens is acquired by detector, and the determination of second light spot position obtained based on the imaging system of magnification is also more accurate;First light spot position can also reflect the light spot position of aperture diaphragm in the entrance pupil of objective lens, and second light spot position reflects the light spot position of entrance pupil itself, so the relative position of the two reflects the relative position of illumination optical axis and imaging optical axis, and the position of aperture diaphragm is adjusted according to first light spot position and second light spot position, so that the light spot centers of first light spot position and second light spot position tend to coincide, so the operation is targeted, and illumination optical axis and imaging optical axis can be quickly aligned, the operation is simple, and in the case that the determination of first light spot position and second light spot position is more accurate, the alignment accuracy of illumination optical axis and imaging optical axis is also higher.

[0084] The above only describes the preferred embodiments of the present application, although the preferred embodiments of the present application have been disclosed as above, however, not to limit the present application. Any person skilled in the art, without departing from the scope of the technical scheme of the present application, can make many possible changes and modifications to the technical scheme of the present application by using the disclosed method and technical content, or modify equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the content of the technical scheme of the present application, still belongs to the protection scope of the technical scheme of the present application.

Claims

1. A method of adjusting a detection device, characterized by, The detection device comprises, in order from the object side to the image side, an objective lens, a beam splitter, a tube lens and a detector, and further comprises a Kohler illumination module; an illumination light beam is emitted from the Kohler illumination module, transmitted through the beam splitter to the objective lens, and when an object to be measured is arranged on the side of the objective lens away from the beam splitter, the objective lens reflects the illumination light beam emitted therefrom to obtain a reflected light beam, which is transmitted through the objective lens, the beam splitter and the tube lens in order to reach the detector; The Kohler illumination module comprises a first lens, a second lens and a third lens arranged in order, the illumination light beam is converted into parallel light by the first lens, an aperture stop is located between the second lens and the third lens and at the focal point of the second lens, the second lens and the third lens are focusing lenses, and the third lens is used to focus the illumination light beam on the entrance pupil of the objective lens in combination with the beam splitter; The method comprises: After inserting the aperture stop in the Kohler illumination module and arranging a first auxiliary lens between the beam splitter and the tube lens, a first light spot position of a light spot formed by the aperture stop on the entrance pupil of the objective lens is acquired by the detector; the first auxiliary lens makes the entrance pupil and the image plane of the detector conjugate; When the Kohler illumination module does not provide an illumination light beam and a surface light source is used as the object to be measured, a second light spot position of a light spot of the entrance pupil of the objective lens is acquired by the detector; The position of the aperture stop is fine-adjusted according to the first light spot position and the second light spot position, so that the light spot centers of the first light spot position and the second light spot position tend to coincide.

2. The method of claim 1, wherein, Before the position of the aperture stop is fine-adjusted according to the first light spot position and the second light spot position, the method further comprises: After inserting the aperture stop in the Kohler illumination module and arranging a second auxiliary lens between the tube lens and the detector, a third light spot position of a light spot formed by the aperture stop on the entrance pupil of the objective lens is acquired by the detector; the second auxiliary lens makes the entrance pupil and the image plane of the detector conjugate; When the Kohler illumination module does not provide an illumination light beam and a surface light source is used as the object to be measured, a fourth light spot position of a light spot of the entrance pupil of the objective lens is acquired by the detector; The position of the aperture stop is coarsely adjusted according to the third light spot position and the fourth light spot position, so that the light spot centers of the third light spot position and the fourth light spot position tend to coincide; The second auxiliary lens is removed.

3. The method of claim 2, wherein, The first auxiliary lens is a focusing lens and the second auxiliary lens is a focusing lens.

4. The method of claim 3, wherein, The focal length of the second auxiliary lens is 45 mm, the distance between the second auxiliary lens and the barrel lens is 43.98 mm, and the distance between the second auxiliary lens and the image plane of the detector is 60.07 mm; the focal length of the first auxiliary lens is 90 mm, the distance between the first auxiliary lens and the entrance pupil of the objective lens is 95.17 mm, and the distance between the first auxiliary lens and the barrel lens is 19.17 mm; the distance between the barrel lens and the image plane of the detector is 109.04 mm, the focal length of the objective lens is 2 mm, and the focal length of the barrel lens is 200 mm.

5. The method of claim 1, wherein, The method further comprises: obtaining a light spot center offset parameter of the first light spot position relative to the second light spot position; adjusting the position of the aperture stop in the direction perpendicular to the optical axis according to the light spot center offset parameter.

6. The method of claim 5, wherein, The first light spot position is determined by a first light spot image generated by the detector, and the second light spot position is determined by a second light spot image generated by the detector.

7. The method of claim 6, wherein, The method further comprises: determining the first light spot position according to a first pixel position of the light spot center in the first light spot image; determining the second light spot position according to a second pixel position of the light spot center in the second light spot image; determining the light spot center offset parameter of the first light spot position relative to the second light spot position according to the magnification of the detector and a pixel offset parameter between the first light spot position and the second light spot position.

8. The method according to any one of claims 1 to 7, characterized in that, The detection device further comprises an optical fiber for guiding the illumination light beam to the Kohler illumination module, and the method further comprises: removing the illumination light beam in the optical fiber, or removing the optical fiber to remove the illumination light beam into the Kohler illumination module.

9. The method according to any one of claims 1 to 7, characterized in that, The method further comprises: removing the first auxiliary lens, restoring the illumination light beam into the Kohler illumination module, setting the object to be detected on the side of the objective lens away from the beam splitter, detecting the reflected light beam from the object to be detected by the detector, and realizing the detection of the object to be detected.

10. The method of claim 9, wherein, The surface to be detected of the object to be detected is arranged on the focal plane of the objective lens, and the focal plane is conjugate with the image plane of the detector.

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