Testing equipment and testing methods

Abstract

The embodiment of the present invention provides a detection device and a detection method for performing scanning detection, wherein the detection device comprises: an illumination light source for providing illumination light; an objective lens for projecting the illumination light onto a detection surface and for imaging the detection surface, wherein the projection of the optical axis of the objective lens on the detection surface is a detection point; a focusing device for determining a measurement point on the detection surface, wherein the measurement point has an offset relative to the detection point along the scanning direction; and for adjusting the objective lens for focusing according to the detection surface position corresponding to the measurement point; and a detection device for detecting the illumination light collected by the objective lens. The embodiment of the present invention can optimize focusing performance and improve imaging quality.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of optical measurement technology, and in particular to a detection device and a detection method. Background Art

[0002] During the semiconductor manufacturing and packaging process, optical equipment is usually used to detect the deformation or surface structure of the wafer.

[0003] As semiconductor process nodes gradually decrease, the manufacturing and packaging processes have put forward higher requirements for detection or measurement technology. Detection equipment usually uses high-power optical microscopes to detect or measure key indicators. In high-power optical microscopes, the objective lens has an extremely limited depth of focus. Therefore, in order to avoid defocus, high-power optical microscopes also need to be equipped with an automatic focusing module. The automatic focusing module detects and focuses in real time according to the relative height between the detection surface and the optical objective lens.

[0004] However, the image resolution of the wafer (or other inspection object) obtained by the optical microscope in the prior art is low, and there is even a problem that the image of the inspection object is only partially collected or not collected. Summary of the invention

[0005] The problem solved by the embodiments of the present invention is to provide a detection device and a detection method to optimize the focusing performance.

[0006] To solve the above problems, an embodiment of the present invention provides a detection device for performing scanning detection, comprising: an illumination light source for providing illumination light; an objective lens for projecting the illumination light onto a detection surface and for collecting the illumination light returned from the detection surface, wherein the projection of the optical axis of the objective lens on the detection surface is a detection point; a focusing device for determining a measurement point on the detection surface, wherein the measurement point has an offset relative to the detection point along the scanning direction; and for adjusting the objective lens for focusing according to the detection surface position corresponding to the measurement point; and a detection device for detecting the illumination light collected by the objective lens.

[0007] Optionally, the focusing device includes: an automatic focusing module, used to provide detection light for ranging, the detection light is projected onto the detection surface through the objective lens to form a light spot; it is also used to obtain the distance between the detection surface and the focal plane of the objective lens based on the measurement point at the light spot position, and perform focusing; an optical path switching mechanism, used to make the light spot form the offset relative to the detection point along the scanning direction.

[0008] Optionally, the autofocus module includes: a sensor for providing the detection light; the detection device also includes: a beam splitter, arranged on the optical path between the autofocus module and the objective lens, for allowing one of the detection light and the illumination light to pass through and the other to reflect.

[0009] Optionally, the beam splitter is used to reflect the detection light to an objective lens, and the optical path switching mechanism includes: a control component, used to control the rotation of the beam splitter.

[0010] Optionally, the optical path switching mechanism includes: a reflector group, used to reflect the light emitted by the sensor toward the beam splitter; and a control electrical component, used to control the rotation of one or more reflectors in the reflector group.

[0011] Optionally, the detection device further includes: a scanning device for driving scanning detection; the optical path switching mechanism is connected to the scanning device and is used to obtain the scanning direction so that the offset direction of the light spot is the same as that of the scanning device.

[0012] Optionally, the scanning device is a bidirectional scanning device; and the optical path switching mechanism enables the light spot to achieve bidirectional offset.

[0013] Optionally, the detection light is returned through the detection surface to form signal light; the focusing device further includes: a receiver, which is used to detect the signal light and obtain the distance between the detection surface and the focal plane of the objective lens according to the signal light.

[0014] Optionally, the detection equipment also includes: a three-dimensional morphology detection device, used to detect the morphology of the surface of the object to be measured and obtain initial height data at each position on the surface of the object to be measured; the focusing device, used to obtain the initial height data of the detection surface from the three-dimensional morphology detection device, and also used to obtain the offset according to the initial height data and focus.

[0015] Optionally, the focusing device is used for causing the detection plane to coincide with the focal plane of the objective lens when the detection device moves the offset so that the detection point coincides with the measurement point.

[0016] Optionally, the focusing device includes a focusing execution system for making the detection surface and the objective lens move relative to each other; the focusing device sets the offset based on the following formula: △=Vs*t; wherein △ is the offset; Vs is the scanning speed of the detection device; t=L / Vz, Vz is the relative movement speed, and L is the distance between the detection surface and the focal plane of the objective lens.

[0017] Correspondingly, an embodiment of the present invention also provides a detection method for performing scanning detection through a detection device, including: providing illumination light; projecting the illumination light onto a detection surface through an objective lens, the projection of the optical axis of the objective lens on the detection surface being a detection point; determining a measurement point on the detection surface according to the relative position of the detection surface and the focus of the objective lens, the measurement point having an offset relative to the detection point along the scanning direction, and focusing based on the measurement point; when the detection device moves to the measurement point, detecting the illumination light collected by the objective lens.

[0018] Optionally, the focusing step includes: providing detection light for ranging, the detection light being projected onto the detection surface through the objective lens to form a light spot; causing the light spot to form the offset along the scanning direction relative to the detection point; obtaining the distance between the detection surface and the focal plane of the objective lens based on the measuring point at the light spot position, and performing focusing.

[0019] Optionally, the step of providing detection light includes: reflecting the detection light to form reflected light, and the reflected light forms a light spot on the detection surface through an objective lens; the step of determining the measurement point includes: controlling the direction of the reflected light so that the light spot forms the offset relative to the detection point along the scanning direction.

[0020] Optionally, the step of making the light spot form the offset relative to the detection point along the scanning direction includes: reflecting the detection light to form initial reflected light; reflecting the initial reflected light again to form reflected light, and the reflected light forms a light spot on the detection surface through an objective lens; controlling the direction of the initial reflected light to control the direction of the reflected light so that the light spot forms the offset relative to the detection point along the scanning direction.

[0021] Optionally, the detection method further includes: before focusing, detecting the morphology of the surface of the object to be measured to obtain initial height data at various positions on the surface of the object to be measured; the step of focusing includes: obtaining the offset according to the initial height data and focusing.

[0022] Optionally, when the detection point of the detection device moves along the scanning direction to coincide with the measurement point, the detection plane coincides with the focal plane of the objective lens.

[0023] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0024] In an embodiment of the present invention, a focusing device determines a measuring point on the detection surface, and the measuring point has an offset relative to the detection point along the scanning direction. During the process of the detection device moving the offset to the detection point, the focusing device focuses based on the measuring point. That is, before the detection device moves to the detection point, the focusing device performs the focusing action in advance, so that there is more time to complete the focusing process, which is beneficial to optimize the focusing effect and obtain a high-resolution image.

[0025] In an optional solution, the focusing device is used to make the detection surface coincide with the focal plane of the objective lens when the detection device moves the offset so that the detection point coincides with the measurement point, so that the focusing is just completed when the detection device scans and moves to the measurement point, thereby ensuring the imaging quality while improving the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of an optical microscope;

[0027] Figure 2 is a schematic diagram of the structure of a detection device according to a first embodiment of the present invention;

[0028] Figure 3 yes Figure 2 A partial enlarged view of the detection equipment shown;

[0029] Figure 4 yes Figure 2 A top view of the detection surface of the detection device shown;

[0030] Figure 5 yes Figure 2 A schematic diagram of another use state of the detection device;

[0031] Figure 6 yes Figure 5 A top view of the detection surface in the illustrated use state;

[0032] Figure 7 is a schematic structural diagram of another detection device according to an embodiment of the present invention;

[0033] Figure 8 is a structural schematic diagram of yet another detection device according to an embodiment of the present invention;

[0034] Fig. 9 It is a flow chart of the detection method of the first embodiment of the present invention. DETAILED DESCRIPTION

[0035] As can be seen from the background technology, the existing technology has the problem of low resolution of images obtained by optical microscope. Figure 1 The following is a schematic diagram of the structure of an optical microscope, and the reasons for the low image resolution are analyzed.

[0036] like Figure 1 In the optical microscope, the optical microscope includes: an illumination light source 10, a beam splitter 11, an objective lens 12, a tube lens 13, a camera 14 and an autofocus module 15. The illumination light emitted by the illumination light source 10 is reflected by the beam splitter 11 and then projected to the detection surface S, illuminating the detection surface S; after the objective lens 12 images the detection surface S, the image is collected by the camera 14 through the tube lens 13, thereby obtaining an image of the detection surface S. The detection equipment performs scanning detection and images each detection surface by moving to different positions, thereby obtaining images of each detection surface of the object to be detected (such as a wafer).

[0037] When the detection device is scanning and detecting, since the heights of the various detection surfaces of the object to be detected are different, the automatic focusing module 15 is required to perform real-time focusing during the detection process. Specifically, the automatic focusing module 15 emits a laser to measure the distance of the detection surface S, and adjusts the position of the objective lens 12 along the direction Z perpendicular to the detection surface according to the relative position of the detection surface S and the focal plane of the objective lens 12, thereby achieving real-time detection and focusing.

[0038] It should be noted that it takes a certain amount of time for the automatic focusing module 15 to complete the focusing from detection to completion. When the automatic focusing module 15 has not yet completed focusing according to the current detection surface S, the camera 14 has already started to collect images. The resolution of the image captured is low, which affects the detection effect.

[0039] Even when the scanning speed of the detection equipment is too fast, the detection equipment has already started to move to the next detection surface position for detection before the focusing is completed. When the camera 14 is shooting, the detection surface S is no longer within the camera's field of view and cannot be captured by the camera 14, thereby affecting the performance of the detection equipment.

[0040] In order to solve the above technical problems, an embodiment of the present invention provides a detection device for performing scanning detection, including: an illumination light source for providing illumination light; an objective lens for projecting the illumination light onto a detection surface and for imaging the detection surface, the projection of the optical axis of the objective lens on the detection surface being a detection point; a focusing device for determining a measurement point on the detection surface, the measurement point having an offset relative to the detection point along the scanning direction; and for adjusting the objective lens for focusing according to a detection surface position corresponding to the measurement point; and an image acquisition device for acquiring an image formed by the objective lens on the detection surface.

[0041] In the embodiment of the present invention, the focusing device determines a measuring point on the detection surface, and the measuring point has an offset relative to the detection point along the scanning direction. In the process of the detection device moving the offset to the detection point, the focusing device focuses based on the measuring point. That is to say, before the detection device moves to the detection point, the focusing device performs the focusing action in advance, so that there is more time to complete the focusing process, which is beneficial to optimize the focusing effect and obtain high-resolution images.

[0042] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0043] refer to Figure 2 , is a schematic diagram of the structure of a detection device according to a first embodiment of the present invention.

[0044] The detection principle of the detection device of this embodiment is: to magnify and image the detection surface by optical imaging, to collect images, and then to analyze the surface information of the detection surface based on the collected images.

[0045] The detection device comprises: an illumination light source 110, an objective lens 112, a focusing device 120 and a detection device.

[0046] The illumination light source 110 is used to provide illumination light. The illumination light is used to illuminate the detection surface W so that the detection device can capture an image of the illuminated detection surface W.

[0047] Specifically, the illumination light source 110 may be a white light source, for example, a commonly used industrial light source such as a mercury lamp.

[0048] The objective lens 112 is a part of the optical microscope, and is used to project the illumination light onto the detection surface W, and also to collect the illumination light returned from the detection surface. The aberration of the image formed along the optical axis of the objective lens 112 is minimal, and the image quality is high. Therefore, the projection of the optical axis of the objective lens 112 on the detection surface W is taken as the detection point B.

[0049] In this embodiment, the objective lens 112 is a high-power objective lens, which magnifies the detection surface W by more than 40 times, thereby magnifying the fine structure of the detection surface and achieving high-precision detection. Specifically, the objective lens 112 can be a plurality of lens groups, which are used to reduce aberrations and improve imaging quality.

[0050] The illumination light forms reflected light with detection surface information after passing through the detection surface W, such as Figure 2 As shown, the reflected light is transmitted through the objective lens 112 and then enters the tube lens 113. The tube lens 113 is also a part of the optical microscope and is used to converge the reflected light to the detection device.

[0051] In this embodiment, the detection device is used to obtain an image of the detection surface based on the illumination light collected by the objective lens. The detection device detects the detection surface based on the image to obtain the size or thickness of the target to be measured or the position of the target to be measured. In other embodiments, the detection device may not image the detection surface; specifically, the detection device is used to obtain the thickness or size of the target to be measured on the surface of the detection surface based on the light intensity of the illumination light collected by the objective lens. The target to be measured is a film layer, a metal wire or a defect. The detection device includes: a camera 114, which captures the image of the detection surface W after being magnified by an optical microscope, and outputs the image of the detection surface.

[0052] Please continue to refer to Figure 2The detection device of the embodiment of the present invention further includes, on the optical path of the illumination light emitted by the illumination light source 110: a first beam splitter 111, which is used to reflect the illumination light so as to project it onto the objective lens 112, and then be converged to the detection point B by the objective lens 112. The first beam splitter 111 can also transmit the illumination light reflected by the detection surface W so as to enter the detection device. The first beam splitter 111 can change the direction of the optical path so that the illumination light source 110 is not located on the imaging optical path of the optical microscope. On the one hand, it can reduce the interference of the imaging optical path and ensure the optical imaging quality; on the other hand, it can realize the reasonable spatial configuration of each optical element of the optical detection device and improve the compactness of the optical detection device.

[0053] It should be noted that when the detection device performs detection, it adopts a scanning detection method, moves to different positions on the surface of the detection object to perform imaging, and collects corresponding images at each position, thereby completing the detection of the entire detection object. The surface of the detection object at each scanning position of the optical microscope is the detection surface.

[0054] The surface of the object to be tested usually has ups and downs, so the relative distance between the detection surface and the objective lens will change at each scanning detection position. In order to improve the imaging quality, the detection device needs to perform focusing processing on different detection surfaces when performing scanning detection. Specifically, when focusing, the position of the objective lens is adjusted along the optical axis direction Z of the objective lens 112 (the direction perpendicular to the detection surface W), so that the detection surface W is set within the focal depth range of the objective lens 112 to improve the imaging quality. Furthermore, the detection surface W is set at the focal plane position of the objective lens 112 to obtain a high-resolution image.

[0055] The higher the magnification of the objective lens, the more limited the depth of focus, which in turn places higher requirements on focusing. Figure 2 As shown, the detection device of the embodiment of the present invention further includes: a focusing device 120, which is used to achieve real-time automatic focusing. In order to achieve focusing, the focusing device 120 needs to obtain the position information of the detection surface W, that is, the distance between the detection surface W and the focal plane of the objective lens 112; on the other hand, adjust the position of the objective lens 112 so that the focal plane of the objective lens 112 coincides with the detection surface W. After focusing, when the image of the detection surface W is collected by the image acquisition device 114, a high-resolution image can be obtained, thereby improving the detection accuracy.

[0056] The focusing device 120 in the detection device of this embodiment includes: an automatic focusing module 115, which is used to provide detection light for distance measurement, and the detection light is projected onto the detection surface W through the objective lens to form a light spot; it is also used to obtain the distance between the detection surface W and the focal plane of the objective lens based on the measurement point A at the light spot position, and perform focusing.

[0057] In this embodiment, the automatic focusing module 115 is a laser ranging module. In other embodiments, the automatic focusing module can also be an interferometer, a differential phase shift interferometer module or a spectral confocal module.

[0058] The automatic focusing module 115 includes: a sensor (not shown), a focusing execution system (not shown), and a motor control module (not shown). The working principle of the automatic focusing module 115 is described below in combination with the functions of several components.

[0059] The sensor is used to provide detection light to measure the distance of the detection surface W. For example, the sensor is a laser that emits a laser beam for distance measurement. The detection light is projected onto the detection surface W to form a light spot, which is the measurement point A of the sensor, that is, the sensor measures the distance through the measurement point A.

[0060] The focusing execution system is used to make the detection surface and the objective lens move relative to each other. In this embodiment, the focusing execution system is a motor connected to the mechanical structure of the objective lens 112, and is used to drive the objective lens 112 to move along the optical axis direction Z.

[0061] The motor control module controls the motor to drive the objective lens 112 to move the detection surface W to the focal plane position based on the distance of the detection surface W obtained by the sensor at the measurement point A and the focal plane of the objective lens 112, the speed of the focusing execution system and other parameters.

[0062] The detection light is returned through the detection surface to form signal light; the focusing device also includes: a receiver (not shown) for detecting the signal light and obtaining the distance between the detection surface and the focal plane of the objective lens according to the signal light.

[0063] Continue to refer Figure 2 In this embodiment, the focusing device 120 further includes: an optical path switching mechanism 118, which is used to make the light spot have an offset relative to the detection point B along the scanning direction.

[0064] The detection light used by the automatic focusing module 115 for distance measurement is eccentrically arranged relative to the optical axis of the objective lens 112 along the scanning direction, so that the focused measurement point A and the objective lens imaging detection point B have an offset along the scanning direction. In this way, when the automatic focusing module 115 starts to perform focusing based on the measurement point A, the detection device is still located at the detection point B; when the detection device moves to the position of the measurement point A due to scanning detection, the automatic focusing module 115 has performed the focusing action for a period of time, so there is more time to perform focusing before imaging and image acquisition. In other words, when the detection device moves to the measurement point A and makes the detection point B coincide with the measurement point A, the focusing effect is better because the focusing has been performed in advance. Accordingly, high-quality imaging can be obtained through the objective lens 112, and then a high-resolution image can be obtained.

[0065] It should be noted that when focusing is performed, the image quality can be guaranteed by making the detection surface W within the focal depth range of the objective lens 112. Therefore, when the offset is preset, the detection surface W can be used as a reference for the completion of focusing based on the detection surface W being within the focal depth range. In an optional solution, the focusing device 120 is used to make the detection surface W coincide with the focal plane of the objective lens when the objective lens 112 moves the offset so that the detection point B coincides with the measurement point A. Compared with making the detection surface W within the focal depth range, by setting the offset based on the focal plane as the reference for completing focusing, the detection surface W can obtain a higher quality image.

[0066] It should also be noted that when the offset is preset, if the offset is too large, when the detection device scans from the detection point B to the measurement point A, the focusing has been completed, which can ensure high-quality imaging. However, since the objective lens has completed focusing but has not yet started to detect the measurement point A, it is also easy to cause the detection time to be extended. If the offset is too small, the focusing has not been completed, thereby affecting the imaging quality. In an optional solution, the focusing can be completed when the detection device scans from the detection point B to the measurement point A, that is, when the detection point B of the detection device moves along the scanning direction to coincide with the measurement point A, the detection surface W coincides with the focal plane of the objective lens 112, thereby reducing the waiting time when the focusing is completed and the image is not yet captured, thereby ensuring the imaging quality while taking into account the detection efficiency.

[0067] Combined with reference Figure 3 and Figure 4 , respectively shown Figure 2 The enlarged partial view and the top view of the detection surface illustrate the principle of setting the offset of the focusing device 120. The focusing device 120 sets the offset △ based on the following formula:

[0068] △=Vs*t……Formula 1

[0069] Wherein, △ is the offset from detection point B to measurement point A along the scanning direction; Vs is the scanning speed of the detection equipment, and t is the time from detection point B to measurement point A;

[0070] t=L / Vz……Formula 2

[0071] Vz is the speed of the relative movement, L is the distance between the detection surface and the focal plane of the objective lens ( Figure 3 The distance between the two.

[0072] Where Vs and Vz are parameters of each component of the detection device and are known quantities. In practical applications, the time t spent on focusing can be calculated by formula 2 based on L obtained by real-time distance measurement of the detection light; because in this embodiment, when the detection device scans from the detection point B to the measurement point A, the focusing is just completed; therefore, the time from the detection point B to the measurement point A is also t, and the t calculated by formula 2 can be substituted into formula 1 to obtain the offset △.

[0073] Please continue to refer to Figure 2 , the detection device includes: a second beam splitter 117, which is arranged on the optical path between the automatic focusing module 115 and the objective lens 112, and is arranged on the optical path between the automatic focusing module and the objective lens, and is used to make one of the detection light and the illumination light pass through and the other reflect. Specifically, in this embodiment, the second beam splitter 117 is used to reflect the detection light to the objective lens 112, and the reflected light of the detection light is projected onto the detection surface W after passing through the objective lens 112 to form a light spot, and the light spot is the position of the detection point B. The second beam splitter 117, which is located on the optical axis of the objective lens, is also used to make the light formed after reflection from the detection surface pass through, so that it can be detected by the image acquisition device.

[0074] The optical path switching mechanism 118 includes: a control component 116, which is used to control the rotation of the second beam splitter 117 (counterclockwise direction of the text opposite surface), thereby changing the direction of the detection light, so that the direction of the detection light deviates from the optical axis direction of the objective lens 112, thereby forming a measurement point A deviating from the detection point B on the detection surface W. In the embodiment of the present invention, the control component 116 and the second beam splitter 117 cooperate to make the amount of deviation of the measurement point A from the detection point B meet the requirements of the offset △ in formula 1.

[0075] The control device is connected to the motor, and the motor controls the rotation of the second beam splitter 117 through the control device. In other embodiments, the rotation of the second beam splitter 117 can be controlled manually through the control device.

[0076] It should be noted that in order to make the deflection of the measuring point A relative to the detection point B consistent with the scanning direction, the detection equipment also includes: a scanning device (not shown) for driving the scanning detection, and the optical path switching mechanism 118 is connected to the scanning device for obtaining the scanning direction so that the offset direction of the light spot is the same as that of the scanning motor.

[0077] refer to Figure 5 and Figure 6 , showing Figure 2Schematic diagram of another use state of the detection device and a top view of the detection surface. In the embodiment of the present invention, the scanning device in the detection device is a bidirectional scanning device, which is used to drive the detection device to scan in two opposite directions. Correspondingly, the optical path switching mechanism 118 is used to enable the light spot to achieve bidirectional offset, so that the offset direction of the measurement point relative to the detection point is consistent with the scanning direction.

[0078] Specifically, the control component 116 can control the second beam splitter 117 to rotate in another direction (clockwise direction opposite to the text surface), so that the direction of the detection light deviates from the optical axis direction of the objective lens 112, thereby forming a measurement point C on the detection surface W that deviates from the detection point B.

[0079] It should be noted that in the above embodiment, the focusing device measures distance by detecting light and focuses based on the measured data. In other embodiments, the position of the detection surface can also be measured in other ways to provide reference data for focusing.

[0080] refer to Figure 7 , shows a schematic diagram of another embodiment of the detection device of the present invention. It should be noted that, in order to make the drawings more concise, the attached Figure 7 The illumination light source and the corresponding optical path of the illumination light are omitted in the figure, but this should not limit the present invention. Figure 2 The similarities of the embodiments shown are not repeated here, but the differences are as follows:

[0081] In this embodiment, the automatic focusing module 315 includes: a sensor for providing the detection light.

[0082] The optical path switching mechanism includes: a reflector group 319, including multiple reflectors, used to reflect the light emitted by the sensor toward the second beam splitter 317; a control component 316, used to control the rotation of one or more reflectors in the reflector group 319, so that before the detection light is projected toward the second beam splitter 317, the direction of the detection light is changed through the reflector group 319 to form an initial reflected light.

[0083] In this embodiment, the reflector group 319 includes a first reflector 3191 and a second reflector 3192 opposite to the first reflector 3191. The reflector group 319 is located between the autofocus module 315 and the second beam splitter 317, wherein the first reflector 3191 reflects the detection light emitted by the sensor to the second reflector 3192, and projects the detection light to the second beam splitter 317 after being reflected again by the second reflector 3192, and the reflector group 319 forms initial reflected light after the detection light is reflected, and the initial reflected light is roughly in the same direction as the detection light, so as not to cause deviation in the light propagation direction.

[0084] The control component 316 is connected to any one of the first reflector 3191 and the second reflector 3192, or is connected to both the first reflector 3191 and the second reflector 3192, and changes the direction of the initial reflected light by controlling the rotation of the first reflector 3191 and / or the second reflector 3192, thereby changing the direction of the reflected light passing through the objective lens 312 to form the offset.

[0085] In this embodiment, before the detection light enters the optical microscope, the direction of the detection light is first changed by the optical path switching mechanism 318, so as to minimize the components on the main optical path of the optical microscope, thereby reducing the interference of other components on the main optical path of the optical microscope. In addition, the reflector group 319 and the control component 316 are not located on the main optical path of the optical microscope. Accordingly, the size, position arrangement, etc. of the reflector group 319 and the control component 316 are more flexible and are not limited by the main optical path of the optical microscope.

[0086] refer to Figure 8 , is a schematic structural diagram of yet another detection device according to an embodiment of the present invention.

[0087] Embodiments of the present invention Figure 2 The similarities of the embodiments shown are not repeated here, but the differences are as follows:

[0088] The detection equipment also includes: a three-dimensional morphology detection device 218, which is used to detect the morphology of the surface of the object to be detected and obtain initial height data at each position on the surface of the object to be detected; the focusing device 220 is used to obtain the initial height data of the detection surface W from the three-dimensional morphology detection device 218, and is also used to obtain the offset according to the initial height data and focus.

[0089] The three-dimensional shape detection device 218 is an interferometer, a spectral confocal module, a laser ranging module, a laser triangulation detection module or a differential phase shift interferometer module.

[0090] In an embodiment of the present invention, L in Formula 2 can be obtained based on the initial height data, and then the time t spent on performing focusing can be calculated using Formula 2; the calculated t is substituted into Formula 1 to obtain the offset △, and the focusing device 220 can start performing focusing when the offset △ is ahead of the detection point B. Figure 7 The illustrated embodiment may obtain the height of each detection surface without using detection light, thereby reducing the interference of the detection light on the optical path of the optical microscope, thereby making the optical path structure of the detection device simpler.

[0091] Accordingly, in order to solve the technical problem, an embodiment of the present invention further provides a detection method for performing scanning detection by a detection device, referring to Fig. 9 , shows a schematic flow chart of an embodiment of a detection method of the present invention, the detection method comprising:

[0092] Step S1, providing illumination light;

[0093] Step S2, projecting the illumination light onto a detection surface through an objective lens, wherein the projection of the optical axis of the objective lens on the detection surface is a detection point;

[0094] Step S3, determining a measuring point on the detection surface according to the relative position of the detection surface and the focus of the objective lens, wherein the measuring point has an offset relative to the detection point along the scanning direction, and focusing is performed based on the measuring point;

[0095] Step S4, when the detection device moves to the measurement point, detecting the illumination light collected by the objective lens.

[0096] The following describes each step of the detection method in conjunction with the detection equipment.

[0097] like Figure 2 As shown, the detection surface W can be magnified and imaged by optical imaging, and the magnified image of the detection surface can be captured, and then the surface information of the detection surface can be analyzed based on the captured image.

[0098] Step S1 is executed to provide illumination light. The illumination light is used to illuminate the detection surface W so that the detection device can capture an image of the illuminated detection surface W. Specifically, the illumination light can be white light.

[0099] Step S2 is executed to project the illumination light onto the detection surface W through the objective lens, and the projection of the optical axis of the objective lens 112 on the detection surface is the detection point B. The objective lens 112 is a part of the optical microscope, and the illumination light is projected onto the detection surface W through the objective lens 112, and is also used to form an image on the detection surface W. The aberration of the image formed along the optical axis of the objective lens 112 is minimal, and the image quality is high. Therefore, the projection of the optical axis of the objective lens 112 on the detection surface W is the detection point B.

[0100] Execute step S3, determine the measuring point A on the detection surface according to the relative position relationship between the position of the detection surface W and the focus of the objective lens 112, the measuring point A has an offset relative to the detecting point B along the scanning direction, and focus is performed based on the measuring point A.

[0101] It should be noted that when performing the detection, a scanning detection method is adopted, the detection device is moved to different surface positions of the detection object for imaging, and corresponding images are collected at each position, thereby completing the detection of the entire detection object. The surface of the detection object at each scanning position of the optical microscope is the detection surface.

[0102] The surface of the object to be detected usually has ups and downs, so at each scanning detection position, the relative distance between the detection surface W and the objective lens 112 will change. In order to improve the imaging quality, it is necessary to perform focusing processing on different detection surfaces W when performing scanning detection. Specifically, the detection surface and the objective lens are relatively moved during focusing, for example: the position of the objective lens 112 is adjusted along the optical axis direction Z of the objective lens 112 (the direction perpendicular to the detection surface W), so that the detection surface W is set within the focal depth range of the objective lens 112 to improve the imaging quality. Furthermore, the detection surface W is set at the focal plane position of the objective lens 112 to obtain a high-resolution image.

[0103] In the embodiment of the present invention, the measuring point A and the detection point B are offset along the scanning direction. Thus, when focusing is performed based on the measuring point A, the detection device is still located at the detection point B; when the detection device moves to the position of the measuring point A due to scanning detection, the focusing action has been performed for a period of time, so there is more time to perform focusing before imaging and image acquisition. In other words, when the detection device moves the measuring point A for imaging and image acquisition, since the focusing has been performed in advance, high-quality imaging can be obtained through the objective lens 112, and then a high-resolution image can be obtained.

[0104] It should be noted that when focusing is performed, the detection surface W is located within the focal depth range of the objective lens 112, and the imaging quality can be guaranteed. Therefore, when the offset is preset, the detection surface W can be located within the focal depth range as a reference for the completion of focusing. In an optional solution, in the focusing step, when the detection device moves the offset so that the detection point B coincides with the measurement point A, the detection surface W coincides with the focal plane of the objective lens 112. By setting the offset with the focal plane as the reference for completing the focusing, the detection surface W can obtain a higher quality image.

[0105] It should also be noted that when the offset is preset, if the offset is too large, when the objective lens 112 scans from the detection point B to the measurement point A, the focusing has been completed, which can ensure high-quality imaging. However, since the objective lens 112 has completed focusing but has not yet started to detect the measurement point A, it is also easy to cause the detection time to be extended. In an optional solution, when the detection device scans from the detection point B to the measurement point A, the focusing is just completed, that is, when the detection point B of the detection device moves along the scanning direction to coincide with the measurement point A, the detection surface W coincides with the focal plane of the objective lens 112, thereby reducing the waiting time when the focusing is completed and the image is not yet collected, thereby ensuring the imaging quality while taking into account the detection efficiency.

[0106] Combined with reference Figure 3 and Figure 4 , respectively shown Figure 2 The enlarged partial view and the top view of the detection surface illustrate the principle of setting the offset in the focusing step. The focusing step sets the offset △ based on the following formula:

[0107] △=Vs*t……Formula 1

[0108] Wherein, △ is the offset from detection point B to measurement point A along the scanning direction; Vs is the scanning speed of the detection equipment, and t is the time from detection point B to measurement point A;

[0109] t=L / Vz……Formula 2

[0110] Vz is the relative movement speed between the detection surface and the objective lens, and L is the relative movement speed between the detection surface W and the focal plane of the objective lens 112 ( Figure 3 The distance between the two.

[0111] Where Vs and Vz are parameters of each component of the detection device, which are known quantities. In practical applications, the time t spent on focusing can be calculated based on L obtained by ranging through Formula 2; because in this embodiment, when the detection device scans from detection point B to measurement point A, the focusing is just completed; therefore, the time from detection point B to measurement point A is also t, and the calculated t can be substituted into Formula 1 to obtain the offset △.

[0112] Specifically, the focusing step includes: providing detection light for ranging, the detection light is projected onto the detection surface W through the objective lens 112 to form a light spot; making the light spot form the offset along the scanning direction relative to the detection point B; obtaining the distance between the detection surface W and the focal plane of the objective lens 112 based on the measuring point A at the light spot position, and performing focusing.

[0113] Please continue to refer to Figure 2 , the optical path switching mechanism 118 includes: a second beam splitter 117 and a control component 116. The second beam splitter 117 is arranged on the optical path between the automatic focusing module 115 and the objective lens 112. The detection light is reflected to the objective lens 112 by the second beam splitter 117. The detection light is projected onto the detection surface W after passing through the objective lens 112 to form a light spot, and the light spot is the detection point position, which can change with the incident direction of the detection light. The control component 116 controls the second beam splitter 117 to rotate (counterclockwise relative to the text surface), thereby changing the direction of the detection light, so that the direction of the detection light deviates from the optical axis direction of the objective lens 112, thereby forming a measurement point A deviating from the detection point B on the detection surface W, and the control component 116 and the second beam splitter 117 make the amount by which the measurement point A deviates from the detection point B meet the requirements of the offset △ in formula 1.

[0114] In other embodiments, Figure 7As shown, the direction of the detection light can also be adjusted before the detection light is projected to the second beam splitter 317. Specifically, the detection light is reflected to form an initial reflected light; the initial reflected light is reflected again to form a reflected light, and the reflected light forms a light spot on the detection surface W through the objective lens; the direction of the initial reflected light is controlled, and then the direction of the reflected light is controlled so that the light spot forms the offset relative to the detection point along the scanning direction.

[0115] Specifically, Figure 7 As shown, the autofocus module 315 includes: a sensor for providing the detection light. The optical path switching mechanism includes: a reflector group 319, including a plurality of reflectors, for reflecting the light emitted by the sensor toward the second beam splitter 317; a control component 316, for controlling the rotation of one or more reflectors in the reflector group 319, so that before the detection light is projected toward the second beam splitter 317, the direction of the detection light is changed by the reflector group 319 to form an initial reflected light.

[0116] The direction of the initial reflected light is changed by changing the rotation angle of the reflector through the control component 316 in the optical path switching mechanism 318, thereby changing the direction of the detection light. Before the detection light enters the main optical path of the optical microscope, the detection light is pre-adjusted, so that the size and position arrangement of each optical element can be more flexible without being restricted by the main optical path of the optical microscope.

[0117] The detection method further comprises: before focusing, detecting the morphology of the surface of the object to be detected to obtain initial height data at various positions on the surface of the object to be detected; and obtaining the offset according to the initial height data and focusing.

[0118] like Figure 8 As shown, in the detection method of the embodiment of the present invention, the initial height data can be obtained according to the three-dimensional shape detection device 218, and then the initial height data can be used to obtain L in formula 2, and then the time t spent on focusing can be calculated by formula 2; the calculated t is substituted into formula 1 to obtain the offset △, and the focusing device 220 can start focusing when the offset △ is advanced relative to the detection point B. That is, the height of each detection surface can be obtained by pre-detection of other equipment instead of using the detection light, thereby reducing the interference of the detection light on the optical path of the optical microscope, and thus making the optical path structure simpler.

[0119] Step S4, when the detection device moves to the measurement point, detecting the illumination light collected by the objective lens.

[0120] like Figure 2As shown, since the focusing process is based on the measuring point A, that is, before the detection device moves to the detection point B, the objective lens 112 has already started to perform the focusing action. When the optical microscope moves to the measuring point B, the detection surface W is located at the focal plane position of the objective lens, so at this time, the image of the detection surface is obtained by imaging the detection surface, and then the size or thickness of the target to be measured or the position of the target to be measured is obtained. It should be noted that the detection surface can be detected by the detection device according to the image. In other embodiments, the detection surface may not be imaged; specifically, the thickness or size of the target to be measured on the surface of the detection surface can be obtained according to the light intensity of the illumination light collected by the objective lens. The target to be measured is a film layer, a metal wire or a defect.

[0121] For more technical details about the detection method, please refer to the description in the detection device embodiment.

[0122] The detection method and detection device provided by the embodiments of the present invention enable the measuring point to have an offset relative to the detection point along the scanning direction, that is, before the detection device moves to the detection point, the focusing action is performed in advance, thereby having more time to complete the focusing process, which is conducive to obtaining a high-resolution image.

[0123] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A detection device for performing scanning detection, characterized in that: include: An illumination light source, used for providing illumination light; An objective lens, used to project the illumination light onto a detection surface and to collect the illumination light returned from the detection surface, wherein the projection of the optical axis of the objective lens on the detection surface is a detection point; A focusing device, used for determining a measuring point on the detection surface, wherein the measuring point has an offset relative to the detection point along the scanning direction; It is also used to adjust the objective lens for focusing according to the position of the detection surface corresponding to the measurement point; A detection device, used for detecting the illumination light collected by the objective lens; Wherein, the focusing device comprises: An automatic focusing module, used for providing detection light for distance measurement, the detection light is projected onto the detection surface through the objective lens to form a light spot; and is also used for obtaining the distance between the detection surface and the focal plane of the objective lens based on the measurement point at the light spot position, and performing focusing; The optical path switching mechanism is used to make the light spot form the offset relative to the detection point along the scanning direction.

2. The detection device according to claim 1, characterized in that The automatic focusing module includes: a sensor for providing the detection light; the detection device also includes: The beam splitter is arranged on the optical path between the automatic focusing module and the objective lens, and is used for transmitting one of the detection light and the illumination light and reflecting the other.

3. The detection device according to claim 2, characterized in that The beam splitter is used to reflect the detection light to the objective lens, and the optical path switching mechanism includes: a control component, which is used to control the rotation of the beam splitter.

4. The detection device according to claim 2, characterized in that The optical path switching mechanism comprises: A reflector assembly, used for reflecting the light emitted by the sensor toward the beam splitter; The control electric component is used to control the rotation of one or more reflectors in the reflector group.

5. The detection device according to claim 1, characterized in that: The detection device further comprises: a scanning device for driving scanning detection; The optical path switching mechanism is connected to the scanning device and is used to obtain the scanning direction so that the offset direction of the light spot is the same as that of the scanning device.

6. The detection device according to claim 5, characterized in that The scanning device is a bidirectional scanning device; the optical path switching mechanism enables the light spot to achieve bidirectional deviation.

7. The detection device according to claim 1, characterized in that: The detection light returns through the detection surface to form signal light; The focusing device further comprises: a receiver, which is used to detect the signal light and obtain the distance between the detection surface and the focal plane of the objective lens according to the signal light.

8. The detection device according to claim 1, characterized in that: The detection device also includes: A three-dimensional shape detection device is used to detect the shape of the surface of the object to be measured and obtain the initial height data at each position of the surface of the object to be measured; The focusing device is used to obtain the initial height data of the detection surface from the three-dimensional shape detection device, and is also used to obtain the offset and focus according to the initial height data.

9. The detection device according to any one of claims 1 to 8, characterized in that: The focusing device is used for causing the detection surface to coincide with the focal plane of the objective lens when the detection device moves the offset so that the detection point coincides with the measurement point.

10. The detection device according to any one of claims 1 to 9, characterized in that: The focusing device includes a focusing execution system for relatively moving the detection surface and the objective lens; the focusing device sets the offset based on the following formula: △ = 2Vs*t; Wherein, △ is the offset; Vs is the scanning speed of the detection device; t=L / Vz, Vz is the relative moving speed, and L is the distance between the detection surface and the focal plane of the objective lens.

11. A detection method for performing scanning detection by using the detection device according to any one of claims 1 to 10, characterized in that: include: Providing lighting; The illumination light is projected onto a detection surface through an objective lens, and the projection of the optical axis of the objective lens on the detection surface is a detection point; According to the relative position of the detection surface and the focus of the objective lens, a measuring point is determined on the detection surface, the measuring point has an offset relative to the detection point along the scanning direction, and focusing is performed based on the measuring point; When the detection device moves to the measurement point, the illumination light collected by the detection lens is detected.

12. The detection method according to claim 11, characterized in that: The steps to focus include: Providing detection light for distance measurement, wherein the detection light is projected onto the detection surface through the objective lens to form a light spot; The light spot is caused to form the offset relative to the detection point along the scanning direction; The distance between the detection surface and the focal plane of the objective lens is obtained based on the measurement point at the spot position, and focusing is performed.

13. The detection method according to claim 12, characterized in that: The step of providing detection light includes: reflecting the detection light to form reflected light, and the reflected light forms a light spot on the detection surface through the objective lens; the step of determining the measurement point includes: controlling the direction of the reflected light so that the light spot forms the offset relative to the detection point along the scanning direction.

14. The detection method according to claim 12, characterized in that: The step of causing the light spot to form the offset relative to the detection point along the scanning direction comprises: Reflecting the detection light to form initial reflected light; Reflecting the initial reflected light again to form reflected light, wherein the reflected light forms a light spot on a detection surface through an objective lens; The direction of the initial reflected light is controlled to control the direction of the reflected light so that the light spot forms the offset relative to the detection point along the scanning direction.

15. The detection method according to claim 11, characterized in that: The detection method further comprises: before focusing, detecting the morphology of the surface of the object to be detected to obtain initial height data at various positions on the surface of the object to be detected; The step of focusing includes: obtaining the offset according to the initial height data and focusing.

16. The detection method according to any one of claims 11 to 15, characterized in that: When the detection point of the detection device moves along the scanning direction to coincide with the measurement point, the detection plane coincides with the focal plane of the objective lens.

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