Detection system and detection method

Abstract

The invention provides a detection system and a detection method. The detection system comprises a first bright field detection light path, a second bright field detection light path, a dark field detection light path, a first platform and a second platform, when the dark field detection light path is used for performing dark field detection on the ith to-be-detected object at the dark field position, the target light path is used for performing bright field detection on the (i + 1) th to-be-detected object at the target position; the target light path is a first bright field detection light path or a second bright field detection light path, and the target position is a first bright field position or a second bright field position. The bright field detection light path and the dark field detection light path are separated, and each light path performs detection independently, so that mutual influence between light sources is avoided, and the detection precision of bright field detection and dark field detection is guaranteed. Besides, when bright field detection is carried out on one object to be detected, dark field detection can be carried out on the other object to be detected, that is, parallel detection on the two objects to be detected can be realized, and the detection efficiency is greatly improved.

Description

Technical Field

[0001] This application relates to the field of defect detection, and particularly to a detection system and a detection method. Background Art

[0002] When detecting defects in a large number of objects to be detected, such as wafers, it is necessary to quickly and accurately detect whether there are defects on the surface of the objects to be detected. For an object to be detected, two types of detections, i.e., dark-field detection and bright-field detection, are required. In the related art, there are partially overlapping optical paths between the bright-field detection optical path and the dark-field detection optical path, and the bright-field optical axis and the dark-field optical axis are in the same position, which will cause great interference of the bright-field beam on the dark-field beam and result in low detection accuracy. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide a detection system and a detection method, which ensure the detection accuracy of bright-field detection and dark-field detection and improve the detection efficiency. The specific solutions are as follows: On the one hand, this application provides a detection system, which includes a first bright-field detection optical path, a second bright-field detection optical path, a dark-field detection optical path, a first platform, and a second platform; Both the first platform and the second platform are used to carry the object to be detected. The first platform switches between a first bright-field position and a dark-field position, and the second platform switches between a second bright-field position and the dark-field position; the first bright-field position and the second bright-field position are respectively located on the light-emitting sides of the first bright-field detection optical path and the second bright-field detection optical path, and the dark-field position is located on the light-emitting side of the dark-field detection optical path; While the dark-field detection optical path is used to perform dark-field detection on the i-th object to be detected at the dark-field position, the target optical path is used to perform bright-field detection on the (i + 1)-th object to be detected at the target position; the target optical path is the first bright-field detection optical path or the second bright-field detection optical path, and the target position is the first bright-field position or the second bright-field position; i≥1.

[0004] Optionally, the detection system includes a basic optical path, and the basic optical path includes a first light source for emitting a first light beam; the dark-field detection optical path includes an adjustment module; When the adjustment module is in the first state, the dark-field detection optical path is used to make the first light beam obliquely incident on the object to be detected for dark-field detection; When the adjustment module is in the second state, the dark-field detection optical path is used to make the first light beam vertically incident on the object to be detected for dark-field detection.

[0005] Optionally, the detection system includes a first scanning optical path and a second scanning optical path; the first bright field position is located on the light-emitting side of the first scanning optical path, and the second bright field position is located on the light-emitting side of the second scanning optical path; While the first bright field detection optical path is used to perform bright field detection on the i-th object to be measured located at the first bright field position, the first scanning optical path is used to perform scanning processing on the i-th object to be measured located at the first bright field position; While the second bright field detection optical path is used to perform bright field detection on the i-th object to be measured located at the second bright field position, the second scanning optical path is used to perform scanning processing on the i-th object to be measured located at the second bright field position.

[0006] Optionally, the detection system includes a basic optical path and a switching module, and the basic optical path includes a first light source and a first beam splitting module; The first beam splitting module is used to split the first light beam emitted by the first light source into a dark field detection light beam incident on the dark field detection optical path and a target scanning light beam incident on the first scanning optical path or the second scanning optical path; the switching module is used to switch the scanning light beam between the first scanning optical path and the second scanning optical path.

[0007] Optionally, the detection system includes a basic optical path, the switching module and a second light source, and the basic optical path includes a first light source and a first beam splitting module; The first beam splitting module is used to split the first light beam emitted by the first light source into a redundant light beam and a dark field detection light beam incident on the dark field detection optical path; The second light source is used to emit a first scanning light beam, and the switching module is used to switch the first scanning light beam between the first scanning optical path and the second scanning optical path.

[0008] Optionally, the basic optical path further includes a light absorption module located on the side where the redundant light beam is emitted by the first beam splitting module, and the light absorption module is used to absorb the redundant light beam.

[0009] Optionally, the optical power of the first light source is greater than that of the second light source.

[0010] Optionally, the detection system includes a basic optical path, a second light source and a third light source, and the basic optical path includes a first light source and a first beam splitting module; The first beam splitting module is used to split the first light beam emitted by the first light source into a redundant light beam and a dark field detection light beam incident on the dark field detection optical path; The second light source is used to emit a first scanning light beam incident on the first scanning optical path; The third light source is configured to emit a second scanning beam that is incident on the second scanning optical path.

[0011] Optionally, the dark field detection optical path further includes a switch; When the switch is in the open state, the switch is configured to perform dark field detection on target defects belonging to the second defect category on the surface of the object to be measured by the dark field detection beam; When the switch is in the closed state, the switch is configured to prevent the dark field detection beam from performing dark field detection on target defects belonging to the first defect category on the surface of the object to be measured; in the defect scan result obtained by completing the scan process on the i-th object to be measured, the minimum value of the first light intensity range corresponding to the first defect category is greater than the maximum value of the second light intensity range corresponding to the second defect category.

[0012] On the other hand, an embodiment of the present application further provides a detection method, which is applied to a detection system. The method includes: Moving the i-th object to be measured from the initial bright field position to the dark field position; the initial bright field position is the first bright field position or the second bright field position, and the i-th object to be measured has completed bright field detection at the initial bright field position; Placing the (i + 1)-th object to be measured at the target bright field position; the target bright field position is different from the initial bright field position; While performing dark field detection on the i-th object to be measured at the dark field position by the dark field detection beam based on the dark field detection optical path, performing bright field detection on the (i + 1)-th object to be measured at the target position based on the target optical path.

[0013] Optionally, the detection system includes a basic optical path, and the basic optical path includes a first light source configured to emit a first beam; the dark field detection optical path includes an adjustment module; performing dark field detection on the i-th object to be measured at the dark field position by the dark field detection beam based on the dark field detection optical path includes: Turning on the first light source and using the first beam as the dark field detection beam; The adjustment module is in the first state, and based on the dark field detection optical path, the dark field detection beam is obliquely incident on the i-th object to be measured at the dark field position for dark field detection; The adjustment module is in the second state, and based on the dark field detection optical path, the dark field detection beam is vertically incident on the i-th object to be measured at the dark field position for dark field detection.

[0014] Optionally, the detection system includes a first scanning optical path and a second scanning optical path; the first bright-field position is located on the light-emitting side of the first scanning optical path, and the second bright-field position is located on the light-emitting side of the second scanning optical path; while performing dark-field detection on the i-th object to be measured at the dark-field position through the dark-field detection beam based on the dark-field detection optical path, performing bright-field detection on the (i + 1)-th object to be measured at the target position based on the target optical path includes: While performing dark-field detection on the i-th object to be measured at the dark-field position through the dark-field detection beam based on the dark-field detection optical path, performing bright-field detection on the (i + 1)-th object to be measured at the target position based on the target optical path, and performing scanning processing on the (i + 1)-th object to be measured at the target position through the target scanning beam based on the target scanning optical path; The target scanning optical path is the first scanning optical path or the second scanning optical path, the first bright-field position is located on the light-emitting side of the first scanning optical path, and the second bright-field position is located on the light-emitting side of the second scanning optical path.

[0015] Optionally, the detection system includes a basic optical path and a switching module, and the basic optical path includes a first light source and a first beam splitting module; before performing dark-field detection on the i-th object to be measured at the dark-field position through the dark-field detection beam based on the dark-field detection optical path, performing bright-field detection on the (i + 1)-th object to be measured at the target position based on the target optical path, and performing scanning processing on the (i + 1)-th object to be measured at the target position through the target scanning beam based on the target scanning optical path, the method further includes: Turn on the first light source, and through the switching module and the first beam splitting module, divide the first beam emitted by the first light source into the dark-field detection beam incident on the dark-field detection optical path and the target scanning beam incident on the target scanning optical path.

[0016] Optionally, the detection system includes a basic optical path, the switching module and a second light source, and the basic optical path includes a first light source and a first beam splitting module; before performing dark-field detection on the i-th object to be measured at the dark-field position through the dark-field detection beam based on the dark-field detection optical path, performing bright-field detection on the (i + 1)-th object to be measured at the target position based on the target optical path, and performing scanning processing on the (i + 1)-th object to be measured at the target position through the target scanning beam based on the target scanning optical path, the method further includes: Through the first beam splitting module, divide the first beam emitted by the first light source into a redundant beam and the dark-field detection beam incident on the dark-field detection optical path; Turn on the second light source, and through the switching module, make the target scanning beam emitted by the second light source incident on the target scanning optical path.

[0017] Optionally, the detection system includes a basic optical path, a second light source, and a third light source. The basic optical path includes a first light source and a first beam splitting module; while performing dark field detection on the i-th object to be measured in the dark field position through the dark field detection beam based on the dark field detection optical path, performing bright field detection on the (i + 1)-th object to be measured in the target position based on the target optical path, and before performing scanning processing on the (i + 1)-th object to be measured in the target position through the target scanning beam based on the target scanning optical path, the method further includes: Through the first beam splitting module, split the first beam emitted by the first light source into a redundant beam and the dark field detection beam incident on the dark field detection optical path; Determine a target light source based on the target scanning optical path; the target light source is the second light source or the third light source; Turn on the target light source, use the beam emitted by the target light source as the target scanning beam, and make the target scanning beam incident on the target scanning optical path.

[0018] Optionally, in the defect scanning result obtained by performing scanning processing on the i-th object to be measured, it includes the defect positions of each defect on the surface of the i-th object to be measured and the light intensity of each defect; Before performing dark field detection on the i-th object to be measured in the dark field position through the dark field detection beam based on the dark field detection optical path, the method further includes: Determine the defect category to which each defect belongs based on the light intensity; different defect categories correspond to different light intensity ranges; The performing dark field detection on the i-th object to be measured in the dark field position through the dark field detection beam based on the dark field detection optical path includes: Performing dark field detection on each position on the surface of the i-th object to be measured through the dark field detection beam based on the dark field detection optical path; When performing dark field detection on a target defect at a target defect position, perform defect detection on the target defect through the dark field detection beam with a target optical power; the target optical power is determined based on the defect category to which the target defect belongs.

[0019] Optionally, the optical power of the target scanning beam is less than the optical power of the dark field detection beam; when the defect category to which the target defect belongs is the first defect category, the target optical power is the first value; when the defect category to which the target defect belongs is the second defect category, the target optical power is the second value; The minimum value of the first light intensity range corresponding to the first defect category is greater than the maximum value of the second light intensity range corresponding to the second defect category; the first value is less than the second value.

[0020] Optionally, the dark field detection optical path further includes a switch; the defect detection of the target defect by using the dark field detection beam with the target optical power includes: When the target defect belongs to the second defect category, controlling the switch to be in an open state, and the dark field detection beam passes through the switch to perform defect detection on the target defect; When the target defect belongs to the first defect category, controlling the switch to be in a closed state, and the dark field detection beam is blocked by the switch, and no defect detection is performed on the target defect.

[0021] The embodiment of the present application provides a detection system and a detection method. The detection system includes a first bright field detection optical path, a second bright field detection optical path, a dark field detection optical path, a first platform and a second platform; both the first platform and the second platform are used to carry the object to be detected. The first platform switches between a first bright field position and a dark field position, and the second platform switches between a second bright field position and a dark field position; the first bright field position and the second bright field position are respectively located on the light output sides of the first bright field detection optical path and the second bright field detection optical path, and the dark field position is located on the light output side of the dark field detection optical path; while the dark field detection optical path is used to perform dark field detection on the i-th object to be detected at the dark field position, the target optical path is used to perform bright field detection on the (i + 1)-th object to be detected at the target position; the target optical path is the first bright field detection optical path or the second bright field detection optical path, and the target position is the first bright field position or the second bright field position; i≥1.

[0022] In the embodiment of the present application, by separating the bright field optical axis and the vertical dark field optical axis, each optical path performs detection independently, avoiding the mutual influence between the light beams, and ensuring the detection accuracy of the bright field detection and the dark field detection. In addition, by setting two bright field detection optical paths and one dark field detection optical path, and setting three positions (the first bright field position, the second bright field position and the dark field position) to cooperate with the two platforms, the first platform can be moved to the first bright field position that will not be occupied by the second platform, so that the first platform and the second platform can start moving at the same time, greatly improving the platform moving efficiency, making the transfer of the object to be detected more convenient. While performing bright field detection on one object to be detected, dark field detection can be performed on another object to be detected, that is, parallel detection of two objects to be detected can be realized, greatly improving the detection efficiency while completing bright field and dark field detections. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0024] Figure 1a Shows a schematic diagram of a detection system provided by an embodiment of the present application; Figure 1b Shows a schematic diagram of another detection system provided by an embodiment of the present application; Figure 1c Shows a schematic layout diagram of a bright field position and a dark field position provided by an embodiment of the present application; Figure 2 Shows a schematic diagram of a polarization module provided by an embodiment of the present application; Figure 3 Shows a schematic diagram of another detection system provided by an embodiment of the present application; Figure 4 Shows a schematic diagram of another detection system provided by an embodiment of the present application; Figure 5 Shows a schematic diagram of another detection system provided by an embodiment of the present application; Figure 6 Shows a schematic flowchart of a detection method provided by an embodiment of the present application; Figure 7 Shows a schematic diagram of a moving stage provided by an embodiment of the present application. Detailed Embodiments

[0025] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will provide a detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings.

[0026] In the following description, many specific details are set forth to fully understand the present application. However, the present application can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0027] For ease of understanding, the following will provide a detailed description of a detection system and a detection method provided by an embodiment of the present application in conjunction with the accompanying drawings.

[0028] Reference Figure 1aAs shown in the figure, it is a schematic diagram of a detection system provided by an embodiment of the present application. The detection system includes a first bright-field detection optical path 101, a second bright-field detection optical path 102, a dark-field detection optical path 103, a first platform 14, and a second platform 19.

[0029] The object to be measured is an object that needs to be defect-detected. The object to be measured can be, for example, a wafer, etc., and specifically can be a non-patterned wafer. The surface of the object to be measured usually has various types of defects, such as particles, area defects, slipline defects, cluster defects, scratches, crystal originated particles (COP), large-area and flat defects, etc. Bright-field detection and dark-field detection can be used for the above-mentioned defect detection.

[0030] In a possible implementation manner, in order to comprehensively and accurately detect the defects existing in the object to be measured, bright-field detection and dark-field detection can be combined for defect detection. The dark field mainly detects particles, area defects, slipline defects, cluster defects, scratches, and crystal originated particles. Due to its high longitudinal resolution and low lateral resolution, the bright field is mainly used to detect large-area and flat defects such as water stains and residues.

[0031] Both the first bright-field detection optical path 101 and the second bright-field detection optical path 102 are optical paths for performing bright-field detection on the object to be measured. Bright-field detection refers to detecting the defects of the object to be measured through the reflected light on the surface of the object to be measured in a bright environment.

[0032] The bright-field detection optical path can include a bright-field light source, a polarizer, a semi-transparent and semi-reflective mirror, a differential interference contrast (DIC) prism, an objective lens, a quarter-wave plate, a tube lens, a filter, and a detector, etc. The bright-field light source can be, for example, a laser light source, a light-emitting diode (LED) light source, etc. The beam emitted by the bright-field light source passes through the polarizer to obtain linearly polarized light. The linearly polarized light is decomposed into two polarized lights with perpendicular vibrations and a certain phase difference after passing through the semi-transparent and semi-reflective mirror. After the two coherent light beams with extremely small slit distances irradiate the surface of the object to be measured through the objective lens, the minute unevenness at each point on the surface of the object to be measured in the field of view will cause an optical path difference between these two beams. The returned beams are re-converged through the semi-transparent and semi-reflective mirror, and then their vibration directions are made the same through the quarter-wave plate to cause interference. After passing through the tube lens and the filter, they are received by the detector. The details on the surface of the object to be measured become enhanced in light and dark contrast due to the interference and amplitude change of the beams, and the image output by the detector presents a three-dimensional relief-like effect, thereby realizing bright-field detection.

[0033] Reference Figure 1a As shown, the first bright-field detection optical path 101 includes a first bright-field light source 26a, a first polarizer 27a, a first half-transmissive and half-reflective mirror 28a, a first DIC prism 29a, a first objective lens 30a, a first quarter-wave plate 31a, a first tube lens 32a, a first filter 33a, and a first detector 34a. The second bright-field detection optical path 102 includes a second bright-field light source 26b, a second polarizer 27b, a second half-transmissive and half-reflective mirror 28b, a second DIC prism 29b, a second objective lens 30b, a second quarter-wave plate 31b, a second tube lens 32b, a second filter 33b, and a second detector 34b. In addition, if the objective lens has a built-in DIC prism, there is no need to set up a DIC prism, and an objective lens with a built-in DIC prism can be used instead.

[0034] The dark-field detection optical path 103 is an optical path for performing dark-field detection on the object to be measured. Dark-field detection mainly uses the scattered light on the surface of the object to be measured for defect detection. The dark-field detection optical path 103 may include optical elements capable of realizing dark detection, such as a polarization module, a reflector, a shaping module, etc. Further, vertical dark-field detection is mainly used for detecting, for example, pits, slip lines, etc. These defects usually have the characteristics of a large longitudinal height difference and a small transverse size, that is, relatively "steep" defects. Oblique dark-field is mainly used for detecting convex defects (such as particles).

[0035] The first platform 14 and the second platform 19 are both used to carry the object to be measured. The first platform 14 and the second platform 19 can be, for example, a stage, etc. The first platform 14 can be switched between the first bright-field position 104 and the dark-field position 106, and the second platform 19 can be switched between the second bright-field position 105 and the dark-field position 106. The first bright-field position 104 and the second bright-field position 105 are respectively located on the light output side of the first bright-field detection optical path 101 and the second bright-field detection optical path 102, and the dark-field position 106 is located on the light output side of the dark-field detection optical path 103.

[0036] That is to say, on the light output side of the first bright-field detection optical path 101, there is a first bright-field position 104, and the first bright-field position 104 is used to place the first platform 14 so as to perform bright-field detection on the object to be measured carried by the first platform 14. On the light output side of the second bright-field detection optical path 102, there is a second bright-field position 105, and the second bright-field position 105 is used to place the second platform 19 so as to perform bright-field detection on the object to be measured carried by the second platform 19. In addition, the first platform 14 can move between the first bright-field position 104 and the dark-field position 106. That is, after the object to be measured carried by the first platform 14 completes bright-field detection at the first bright-field position 104, it can follow the first platform 14 to reach the dark-field position 106 for dark-field detection. Similarly, the second platform 19 can move between the second bright-field position 105 and the dark-field position 106. That is, after the object to be measured carried by the second platform 19 completes bright-field detection at the second bright-field position 105, it can follow the second platform 19 to reach the dark-field position 106 for dark-field detection.

[0037] Reference Figure 1c As shown, three positions are shown, namely the first bright-field position 104, the second bright-field position 105, and the dark-field position 106. The first platform 14 can move between the first bright-field position 104 and the dark-field position 106, and the second platform 19 can move between the second bright-field position 105 and the dark-field position 106.

[0038] While the dark-field detection optical path 103 is used to perform dark-field detection on the i-th object to be measured at the dark-field position 106, the target optical path is used to perform bright-field detection on the (i + 1)-th object to be measured at the target position; the target optical path is the first bright-field detection optical path 101 or the second bright-field detection optical path 102, and the target position is the first bright-field position 104 or the second bright-field position 105; i ≥ 1.

[0039] Specifically, the i-th object to be measured and the (i + 1)-th object to be measured can be processed simultaneously. Since both the first bright-field detection optical path 101 and the second bright-field detection optical path 102 can achieve bright-field detection, they can both be used as the target optical path. When the target optical path is the first bright-field detection optical path 101, the target position is the first bright-field position 104, and when the target optical path is the second bright-field detection optical path 102, the target position is the second bright-field position 105.

[0040] That is to say, while performing dark-field detection on the i-th object to be measured at the dark-field position 106 through the dark-field detection optical path 103, bright-field detection can be performed on the (i + 1)-th object to be measured at the first bright-field position 104 through the first bright-field detection optical path 101. Or, while performing dark-field detection on the i-th object to be measured at the dark-field position 106 through the dark-field detection optical path 103, bright-field detection can be performed on the (i + 1)-th object to be measured at the second bright-field position 105 through the second bright-field detection optical path 102.

[0041] In short, when the target optical path is the first bright-field detection optical path 101, the (i + 1)-th object to be measured is placed on the first platform 14 at the first bright-field position 104, and the i-th object to be measured is placed on the second platform 19 at the dark-field position 106, so as to detect these two objects to be measured simultaneously. When the target optical path is the second bright-field detection optical path 102, the (i + 1)-th object to be measured is placed on the second platform 19 at the second bright-field position 105, and the i-th object to be measured is placed on the first platform 14 at the dark-field position 106, so as to detect these two objects to be measured simultaneously.

[0042] In practical applications, during the detection process, the manipulator can successively transfer two objects to be measured to the first bright-field position 104 and the second bright-field position 105 respectively for bright-field detection. The platform that finishes the bright-field detection first will move to the dark-field position 106 to start dark-field detection. At this time, the other platform will wait at the bright-field position for the object to be measured that is undergoing dark-field detection to finish. After the dark-field detection is completed, this platform will move to the loading / unloading position, and the object to be measured carried by this platform will be put back into the transfer box through the manipulator, and at the same time, another object to be measured will be taken and placed at the bright-field position to start bright-field detection. During this process, the other object to be measured that has already completed bright-field detection will undergo dark-field detection.

[0043] In summary, by separating the bright-field detection optical path and the dark-field detection optical path 103, each optical path performs detection independently, avoiding the mutual influence between light beams, and ensuring the detection accuracy of bright-field detection and dark-field detection. In addition, by setting two bright-field detection optical paths and one dark-field detection optical path 103, and setting three positions (the first bright-field position 104, the second bright-field position 105, and the dark-field position 106) to cooperate with two platforms, trading space for time, the first platform 14 can move to the first bright-field position 104 that will not be occupied by the second platform 19, so that the first platform 14 and the second platform 19 can start moving simultaneously, greatly improving the platform movement efficiency, making the transfer of the object to be measured more convenient. While performing bright-field detection on one object to be measured, dark-field detection can be performed on another object to be measured, that is, parallel detection of two objects to be measured can be realized, greatly improving the detection efficiency, and precisely and comprehensively completing various defect detections of the object to be measured through the cooperation of bright-field and dark-field detections.

[0044] In a possible implementation manner, the detection system may include a basic optical path 100. The basic optical path 100 may include a first light source 1 for emitting a first light beam. The dark-field detection optical path 103 may include an adjustment module 22. When the adjustment module 22 is in the first state, the dark-field detection optical path 103 is used to make the first light beam obliquely incident on the object to be measured for dark-field detection. When the adjustment module 22 is in the second state, the dark-field detection optical path 103 is used to make the first light beam vertically incident on the object to be measured for dark-field detection.

[0045] Specifically, the basic optical path 100 may include a first light source 1. The first light source 1 can be any type of light source, such as a laser, etc., and specifically can be a deep ultraviolet high-power laser. The deep ultraviolet high-power laser can emit continuous or quasi-continuous deep ultraviolet laser beams. In order to reduce the debugging difficulty of the subsequent optical path, the first light source 1 itself can achieve six-degree-of-freedom adjustment. In addition, in order to reduce the impact of subsequent mechanical movement structure shock on the first light source 1, a vibration isolation pad can be added between the first light source 1 and the support structure of the first light source 1 to ensure that the position of the first light source 1 does not change significantly.

[0046] The light beam emitted by the first light source 1 can be denoted as the first light beam, and the first light beam can be used to be incident on the dark field detection optical path 103. When performing dark field detection, for sunken defects such as pits, vertical dark field detection is more suitable, and for protruding defects such as particles, inclined dark field detection is more suitable. Therefore, vertical dark field detection and inclined dark field detection can be performed on the object to be measured, thereby improving the detection accuracy.

[0047] The illumination method of vertical dark field detection is to irradiate vertically from top to bottom onto the surface of the object to be measured. For sunken type defects, using the vertical illumination method is more conducive to defect detection, such as slip lines, pits, etc. The illumination method of inclined dark field detection is that the light beam is obliquely incident on the surface of the object to be measured, and the detection accuracy for protruding defects will be higher.

[0048] The dark field detection optical path 103 may include an adjustment module 22. The adjustment module 22 can be used to adjust the dark field detection optical path 103, thereby realizing the switching between inclined dark field detection and vertical dark field detection. The adjustment module 22 can be, for example, a movable mirror or a rotatable mirror, etc. By adjusting the adjustment module 22, it can be switched between the first state and the second state. When the adjustment module 22 is in the first state, at this time, the dark field detection optical path 103 changes, and the first light beam can be obliquely incident on the surface of the object to be measured for defect detection. When the adjustment module 22 is in the second state, the first light beam can be vertically incident on the surface of the object to be measured for defect detection. Vertical incidence can be understood as the angle between the first light beam and the surface of the object to be measured is close to 90°.

[0049] Reference Figure 1a As shown, when the adjustment module 22 is a movable mirror, when the adjustment module 22 is removed from the optical path, it is in the first state at this time, and the first light beam is reflected by the first mirror 25 and then obliquely incident on the surface of the object to be measured. When the adjustment module 22 is moved into the optical path, it is in the second state at this time, and the first light beam is reflected by the adjustment module 22 and the second mirror 35 and then vertically incident on the surface of the object to be measured.

[0050] In this way, two dark-field detections can be performed on a test object, namely, oblique dark-field detection and vertical dark-field detection, so that both concave defects and convex defects of the test object can be detected, improving the detection accuracy and comprehensiveness.

[0051] In addition, other optical elements may also be included in the basic optical path 100, such as Figure 1a In, there is also a slow shutter 2, a beam pointing stabilization module 3, a beam expansion module 4, and a beam adjustment module 40 along the beam propagation direction. The slow shutter 2 is used to control whether the light emitted by the first light source 1 continues to propagate. When the slow shutter 2 is in the closed state, no beam passes through. When the slow shutter 2 is in the open state, the beam emitted by the first light source 1 can pass through. The beam pointing stabilization module 3 can be used to correct the beam pointing. After the first light source 1 is used for a period of time, its pointing may undergo a small angular offset. Due to the long optical path of the subsequent optical path, when it reaches the shaping module, it can no longer meet the requirements of the shaping element. Therefore, a beam pointing stabilization module 3 can be set in the basic optical path 100 to adjust the beam pointing. The beam pointing stabilization module 3 includes a first reflector, a second reflector, a third reflector, a fourth reflector, a first adjustment component (not shown in the figure), a second adjustment component (not shown in the figure), a first detector (not shown in the figure), and a second detector (not shown in the figure). The beam passes through the first reflector, the second reflector, the third reflector, and the fourth reflector in sequence and then exits the beam stabilization system; after the light passes through the second reflector, part of the light is transmitted through the second reflector and transmitted to the first detector; after the light passes through the fourth reflector, part of the light is transmitted through the fourth reflector and transmitted to the second detector. When the light beam emitted by the laser light source is unstable and deviates, the light spots on the first detector and the second detector deviate simultaneously. The first reflector and the second reflector can be adjusted according to the positions of the light spots transmitted to the first detector and the second detector, so that the output light direction of the beam stabilization system remains stable. The beam expansion module 4 can be used to enlarge the spot diameter to meet the usage requirements of the subsequent shaping module. The beam expansion module 4 can be, for example, a one-dimensional beam expansion element, which is designed based on a cylindrical lens pair and a deformed prism pair and is mainly used to adjust the beam size in the narrow axis direction so that the output beam meets the established size requirements to meet the needs of the subsequent shaping optical element. The larger the beam size, the narrower the compressible linewidth. The narrow axis is the linewidth direction corresponding to the final line spot, which can also be called the short side direction of the line spot. In addition, a third reflector 20, a first polarization module 21, a fourth reflector 23, and a third shaping module 24 may also be included in the dark-field detection optical path. The beam adjustment module 40 is mainly used to adjust the beam. As an example, in Figure 1a and Figure 1bIn the embodiment, the beam adjustment module 40 may include a second half-wave plate 6 and a twelfth reflector 41, so as to adjust the beam accordingly. Of course, the beam adjustment module may also include a second half-wave plate 6 and a second polarization beam splitter prism (PBS) 7, and the second polarization beam splitter prism 7 is used to split the beam, so that a part of the split light can be incident on the surface of the object to be measured. At this time, the beam adjustment module 40 is also the first beam splitter module 5.

[0052] Specifically, due to the different materials of the object to be tested, the polarization state of the light beam required for dark field detection or defect scanning may also be different, so a polarization module may be provided to adjust the polarization state of the light beam.

[0053] The polarization module can realize P / S polarization, left-handed (CL) polarization, right-handed (CR) polarization and N / A (empty), refer to Figure 2 , which is a schematic diagram of a polarization module provided in an embodiment of the present application, the polarization module may include four polarizers to achieve four polarization states, and the polarization module may be driven to rotate by a motor to achieve a desired polarization state.

[0054] The shaping module may be a collimated flat-top shaping element, or a free-form surface shaping element, which may provide a single degree of freedom line width compression along the narrow side direction, and the shaping module may be implemented by a diffractive optical element (DOE), a microlens array, a prism, etc. The shaping module may also include a one-dimensional beam expander, a collimated flat-top shaping element, a free-form surface shaper, or any other suitable shaping module known in the art.

[0055] Furthermore, defects such as particles, area defects, slipline defects, cluster defects, scratches, and pits (Crystal Originated Particle, COP) may be large-sized defects or small-sized defects, which are referred to as defect categories in the present invention. As an example, a large-sized defect may be a defect with a size greater than 500nm. In order to detect smaller defects and improve detection accuracy, scattering-based detection requires increasing the laser power of the illumination light. However, high-power illumination can cause large-sized defects to be swept and exploded due to heating, aggravating the contamination of the object to be tested.

[0056] In a possible implementation, the bright field can be used not only to detect defects with a relatively large area and a small longitudinal height difference (such as large-area and flat defects like water stains and residues), but also to detect the above-mentioned large-size defects. Based on the bright field detection records of the first bright field position 104 and the second bright field position 105, the positions of large-size defects on the surface of the object to be measured are detected. In this way, for large-size defects, when performing dark field detection at the dark field position 106, the position where the large-size defect is located is skipped and dark field detection is not performed, so as to avoid the high-power light source in the dark field detection position from sweeping and exploding the large-size defect. That is, when performing defect detection on the object to be measured at the dark field position 106, if the dark field detection beam is incident on the position where the large defect is located, the switch 37 is quickly turned off. After skipping the position where the large defect is located, the switch 37 is turned on again to continue the dark field detection of small defects, as Figure 1b shown. The switch 37 can also be replaced by an acousto-optic modulator (AOM), etc. Moreover, while performing dark field detection on the i-th object to be measured at the dark field position 106 through the dark field detection optical path 103, bright field detection can be performed on the (i + 1)-th object to be measured at the first bright field position 104 through the first bright field detection optical path 101. Or, while performing dark field detection on the i-th object to be measured at the dark field position 106 through the dark field detection optical path 103, bright field detection can be performed on the (i + 1)-th object to be measured at the second bright field position 105 through the second bright field detection optical path 102. That is, the present application can perform bright field detection and dark field detection simultaneously and execute them in parallel, without waiting to perform bright field detection after the defect scanning process ends, which greatly improves the detection efficiency and accurately and comprehensively completes the detection of various defects of the object to be measured through the cooperation of bright field and dark field detection.

[0057] In a possible implementation, the detection system may include a first scanning optical path 201 and a second scanning optical path 202; the first bright field position 104 is located on the light-emitting side of the first scanning optical path 201, and the second bright field position 105 is located on the light-emitting side of the second scanning optical path 202; while the first bright field detection optical path 101 is used to perform bright field detection on the i-th object to be measured at the first bright field position 104, the first scanning optical path 201 is used to perform scanning processing on the i-th object to be measured at the first bright field position 104; while the second bright field detection optical path 102 is used to perform bright field detection on the i-th object to be measured at the second bright field position 105, the second scanning optical path 202 is used to perform scanning processing on the i-th object to be measured at the second bright field position 105.

[0058] When detecting the object to be measured, if the light power reaching the surface of the object to be measured is too large, it is easy to sweep and explode large-size defects scattered on the surface of the object to be measured, thereby contaminating the object to be measured. Therefore, in order to avoid sweeping and exploding the defects, before performing dark field detection, a relatively small light power can be used to perform defect detection and scanning processing first, so as to record the positions of large-size defects on the surface of the object to be measured.

[0059] Specifically, the detection system may further include two scanning optical paths, namely the first scanning optical path 201 and the second scanning optical path 202. The scanning optical paths are mainly used for scanning defects. The scanning optical paths may include a shaping module and at least one mirror, etc., for improving the beam shape and propagation direction. The optical power of the beam in the scanning optical paths can be relatively small to avoid scanning explosion. When the first platform 14 carrying the i-th object to be measured is located at the first bright field position 104, the first scanning optical path 201 can perform scanning processing on the object to be measured. If the second platform 19 carrying the i-th object to be measured is located at the second bright field position 105, the second scanning optical path 202 can perform scanning processing on the object to be measured.

[0060] Reference Figure 3 As shown, the first platform 14 carries the object to be measured, namely Wafer I. The first platform 14 is located at the first bright field position 104. At this time, the detection system can perform scanning processing on Wafer I through the first scanning optical path 201. At the same time, bright field detection can also be performed through the first bright field detection optical path 101. After completing the scanning processing and bright field detection processing, dark field detection is then carried out.

[0061] Similarly, if the second platform 19 carries an object to be measured and the second platform 19 is located at the second bright field position 105, the detection system can perform scanning processing on the object to be measured through the second scanning optical path 202. During the scanning processing, bright field detection can also be performed through the second bright field detection optical path 102. In addition, the scanning processing can also detect slightly larger defects that cannot be detected by bright field detection. For example, bright field detection can detect defects of several micrometers, and the scanning processing can detect defects of several hundred nanometers, realizing comprehensive defect detection.

[0062] In addition, in order to avoid mutual interference between the scanning processing and the bright field detection, the optical wavelength bands of the beam for scanning processing and the beam for bright field detection can be different, and a filter corresponding to the optical wavelength band is set at the detector end used for scanning processing, and a filter is also set at the detector end used for bright field detection, so that the detector can only receive light within this wavelength band, avoiding interference of the bright field detection beam on the scanning result and avoiding interference of the scanning beam on the bright field detection result.

[0063] Among them, the first scanning optical path and the second scanning optical path can be inclined low-power dark field scanning optical paths. When performing two types of detections, namely bright field DIC detection and inclined low-power dark field scanning, on the object to be measured at the same bright field position, the two illumination spots generated by the two optical paths at the bright field position can be aligned, that is, the two illumination spots can coincide. In this way, compared with the non-coincidence of the illumination spots, the scanning time can be saved. Especially when the platform drives the object to be measured to move, dark field scanning and bright field DIC detection can be simultaneously realized for each position on the object to be measured, improving the detection efficiency.

[0064] In addition, referring to Figure 3 as shown, the detection system may further include several mirrors and other optical elements, such as a fifth mirror 8, a second polarization module 9, a target mirror 10. The first scanning optical path may further include a first shaping module 11, a seventh mirror 12, and an eighth mirror 13. The second scanning optical path may further include a ninth mirror 15, a second shaping module 16, a tenth mirror 17, and an eleventh mirror 18.

[0065] In this way, before performing dark-field detection, the object to be measured is first subjected to defect scanning processing, so that the positions of each defect can be known, which is convenient for subsequent corresponding processing of defects of different sizes during dark-field detection. For example, for large-size defects, the position where the large-size defects are located is skipped during dark-field detection without performing dark-field detection, thereby improving the detection accuracy. At this time, in the present application, defect scanning processing is performed while performing bright-field detection, and they are executed in parallel without waiting for the defect scanning processing to end before performing bright-field detection, which greatly improves the detection efficiency.

[0066] In a possible implementation manner, the detection system may include a basic optical path 100 and a switching module. The basic optical path 100 includes a first light source 1 and a first beam splitting module 5; the first beam splitting module 5 is used to split the first light beam emitted by the first light source 1 into a dark-field detection light beam incident on the dark-field detection optical path 103 and a target scanning light beam incident on the first scanning optical path 201 or the second scanning optical path 202; the switching module is used to switch the scanning light beam between the first scanning optical path 201 and the second scanning optical path 202.

[0067] Specifically, in order to simplify the optical path structure, a first light source 1 may also be provided in the detection system, and the illumination for scanning processing and dark-field detection can be realized by using this light source. Referring to Figure 4 as shown, the basic optical path 100 includes a first light source 1 and a first beam splitting module 5, and the first beam splitting module 5 may be a beam splitting prism.

[0068] The first light beam emitted by the first light source 1 is split into two light beams by the first beam splitting module 5, namely a dark-field detection light beam and a target scanning light beam. The dark-field detection light beam can be incident on the dark-field detection optical path 103 for dark-field detection, and the target scanning light beam can be incident on the scanning optical path for scanning processing. The scanning optical path can be the first scanning optical path 201 or the second scanning optical path 202.

[0069] The detection system may further include a switching module, and the switching module is used to realize the switching of the scanning optical path, that is, the target scanning light beam can be incident on the first scanning optical path 201 or the target scanning light beam can be incident on the second scanning optical path 202. The switching module may be a target mirror 10. Referring to Figure 4As shown, when the target mirror 10 is in the optical path, the target scanning beam can be incident on the first scanning optical path 201. When the target mirror 10 is not in the optical path, the target scanning beam can be incident on the second scanning optical path 202.

[0070] In summary, by sharing the same light source, i.e., the first light source 1, for the defect scanning process and the dark field detection, the optical path cost can be saved. And by using the switching module to switch the scanning optical path, the optical path switching can be accurately and efficiently realized.

[0071] In a possible implementation, the detection system may include a basic optical path 100, a switching module, and a second light source 26. The basic optical path 100 includes a first light source 1 and a first beam splitting module 5. The first beam splitting module 5 is used to split the first beam emitted by the first light source 1 into a redundant beam and a dark field detection beam incident on the dark field detection optical path 103. The second light source 26 is used to emit a first scanning beam, and the switching module is used to switch the first scanning beam between the first scanning optical path 201 and the second scanning optical path 202.

[0072] Specifically, in order to more accurately implement the defect scanning process, an independent light source, i.e., the second light source 26, can be configured for the scanning optical path. The beam emitted by the second light source 26 can be denoted as the first scanning beam. The first scanning beam can be incident on the first scanning optical path 201 or the second scanning optical path 202. Under the action of the switching module, it can be controlled which scanning optical path the first scanning beam is incident on.

[0073] At this time, the first beam emitted by the first light source 1 is split into a redundant beam and a dark field detection beam after passing through the first beam splitting module 5, and the dark field detection beam can continue to be incident on the dark field detection optical path 103.

[0074] In a possible implementation, the first beam splitting module 5 may include a second half-wave plate 6 and a second polarization beam splitter (PBS) 7. By rotating the second half-wave plate 6, the optical power of the detection beam can be adjusted. The operation is simple, and accurate adjustment of the optical power can be achieved.

[0075] Reference Figure 4 As shown, the detection system includes 4 light sources, namely the first light source 1, the second light source 26, the first bright field light source 26a, and the second bright field light source 26b. The first light source 1 is used to provide a dark field detection beam for the dark field detection optical path 103. The second light source 26 is used to provide a scanning beam for the scanning optical path. The two bright field light sources are used to provide bright field beams for their respective bright field detection optical paths.

[0076] In summary, by providing an independent light source for the scanning optical path, the adjustment of the optical power of the scanning beam is more free, not limited by the first light source 1, and the optical power requirement for the first light source 1 is reduced. The first light source 1 can select a light source with a smaller optical power, reducing the light source cost.

[0077] In a possible implementation, the basic optical path 100 may further include an optical absorption module located on one side of the redundant beam emitted from the first beam splitting module 5, and the optical absorption module is used to absorb the redundant beam.

[0078] Since the dark field detection optical path 103 only needs to use the dark field detection beam for dark field detection, and the other part of the beam emitted from the first beam splitting module 5, that is, the redundant beam, does not need to be incident on the dark field detection optical path 103. In order to avoid interference of the redundant beam on the dark field detection, an optical absorption module 27 can be set. The redundant beam is absorbed by the optical absorption module 27 after being emitted from the first beam splitting module 5, so as to avoid light leakage and have an adverse effect on the dark field detection optical path 103. The variable attenuation function of the dark field detection optical path 103 can also be retained, that is, the optical power is adjustable. As an example, the optical absorption module 27 can be an optical trap.

[0079] In summary, by setting the optical absorption module 27, the stray light after beam splitting, that is, the redundant beam, can be absorbed, avoiding affecting the dark field detection optical path 103. In addition, the optical power attenuation adjustment of the dark field detection beam can be realized, which can help adjust the dark field detection beam to an appropriate optical power.

[0080] In a possible implementation, the optical power of the first light source 1 is greater than the optical power of the second light source 26.

[0081] Specifically, the second light source 26 is mainly used to provide a scanning beam for the scanning optical path, mainly for detecting large-size defects and recording the positions of large-size defects. In order to avoid blasting large-size defects, the optical power of the second light source 26 can be set to be smaller, less than the optical power of the first light source 1. In this way, using a smaller optical power for defect scanning and a larger optical power for dark field detection can detect various defects and avoid blasting large-size defects.

[0082] In a possible implementation, the detection system may include a basic optical path 100, a second light source 26, and a third light source 36. The basic optical path 100 includes a first light source 1 and a first beam splitting module 5; the first beam splitting module 5 is used to split the first beam emitted by the first light source 1 into a redundant beam and a dark field detection beam incident on the dark field detection optical path 103; the second light source 26 is used to emit a first scanning beam incident on the first scanning optical path 201; the third light source 36 is used to emit a second scanning beam incident on the second scanning optical path 202.

[0083] To further improve the freedom degree of beam optical power adjustment, an independent light source can be set for each scanning optical path, that is, the second light source 26 is set for the first scanning optical path 201, and the third light source 36 is set for the second scanning optical path 202. Refer to Figure 5As shown, the second light source 26 emits a first scanning beam, and the first scanning beam can be incident on the surface of the object to be measured through the first scanning optical path 201. The third light source 36 is used to emit a second scanning beam, and the second scanning beam can be incident on the surface of the object to be measured through the second scanning optical path 202.

[0084] In this way, an independent light source is set for each optical path, and the optical power of the beam in each optical path can be independently adjusted without mutual influence. The adjustment of the optical power is more convenient and flexible, and the defect scanning, bright-field detection, and dark-field detection will all be more accurate.

[0085] In a possible implementation manner, the dark-field detection optical path 103 further includes a switch 37; when the switch 37 is in the open state, the switch 37 is used to perform dark-field detection on the target defect belonging to the second defect category on the surface of the object to be measured; when the switch 37 is in the closed state, the switch 37 is used to prevent the dark-field detection beam from performing dark-field detection on the target defect belonging to the first defect category on the surface of the object to be measured; in the defect scanning result obtained by completing the scanning process for the i-th object to be measured, the minimum value of the first light intensity range corresponding to the first defect category is greater than the maximum value of the second light intensity range corresponding to the second defect category.

[0086] Specifically, the switch 37 can be located in the dark-field detection optical path 103 and is used to control whether the dark-field detection beam can be incident on the surface of the object to be measured. Since during the defect scanning process, the light intensity corresponding to large-sized defects is larger and the light intensity corresponding to small-sized defects is smaller, the first defect category represents large-sized defects, such as large particle defects, and the second defect category represents small-sized defects, such as small particle defects.

[0087] When the target defect belongs to the second defect category, it indicates that the target defect is a small-sized defect, and dark-field detection is mainly for detecting such defects. Therefore, the switch 37 can be controlled to be in the open state so that the dark-field detection beam can pass through the switch 37 to detect the target defect on the surface of the object to be measured.

[0088] When the target defect belongs to the first defect category, it indicates that the target defect is a large-sized defect. Since it has been detected through the defect scanning process and in order to avoid explosion during scanning, there is no need to perform dark-field detection again. Therefore, the switch 37 can be controlled to be in the closed state, and the dark-field detection beam is blocked by the switch 37 and cannot continue to propagate backward, thus not performing defect detection on the target defect.

[0089] In other words, when performing defect detection on the object to be measured, if the dark-field detection beam is incident on the position where the large defect is located, the switch 37 is quickly closed. After skipping the position where the large defect is located, the switch 37 is opened again to continue the dark-field detection of the small defect.

[0090] In summary, a switch 37 is provided in the dark-field detection optical path 103. By closing the switch 37, it is convenient to perform dark-field detection on large-size defects and small-size defects with different optical powers. The operation is convenient, the cost is low, and the explosion of large-size defects can be avoided to the greatest extent.

[0091] Reference Figure 6 As shown, it is a schematic flowchart of a detection method provided by an embodiment of the present application. This method is applied to a detection system and may include the following steps.

[0092] S101, Move the i-th object to be measured from the initial bright-field position to the dark-field position 106.

[0093] The initial bright-field position can be understood as the position where the i-th object to be measured is subjected to bright-field detection. The initial bright-field position can be the first bright-field position 104 or the second bright-field position 105. That is, when the i-th object to be measured is located on the first platform 14, the first bright-field position 104 where the first platform 14 is located is the initial bright-field position. If the object to be measured is located on the second platform 19, the second bright-field position 105 where the second platform 19 is located is the initial bright-field position. The i-th object to be measured has completed bright-field detection at the initial bright-field position.

[0094] That is to say, for the i-th object to be measured, after it completes bright-field detection through the bright-field detection optical path at the initial bright-field position, it can be moved from the initial bright-field position to the dark-field position 106, that is, the platform carrying the i-th object to be measured is moved from the bright-field position to the dark-field position 106.

[0095] S102, Make the (i + 1)-th object to be measured located at the target bright-field position.

[0096] Specifically, the next object to be measured, that is, the (i + 1)-th object to be measured, can be placed on the platform located at another bright-field position. The target bright-field position is different from the initial bright-field position. When the initial bright-field position is the first bright-field position 104, the target bright-field position is the second bright-field position 105. When the initial bright-field position is the second bright-field position 105, the target bright-field position is the first bright-field position 104.

[0097] S103, While performing dark-field detection on the i-th object to be measured at the dark-field position 106 through the dark-field detection optical path 103, perform bright-field detection on the (i + 1)-th object to be measured at the target position based on the target optical path.

[0098] Specifically, at this time, the i-th object to be measured is located at the dark-field position 106, and the (i + 1)-th object to be measured is located at the target bright-field position. Then, these two objects to be measured can be processed simultaneously. That is, the dark-field detection beam is incident on the surface of the i-th object to be measured through the dark-field detection optical path 103 for dark-field detection. At the same time, the target optical path can perform bright-field detection on the (i + 1)-th object to be measured.

[0099] Among them, the target optical path can be the first bright-field detection optical path 101 or the second bright-field detection optical path 102. When the initial bright-field position is the first bright-field position 104, the target optical path is the second bright-field detection optical path 102; when the initial bright-field position is the second bright-field position 105, the target optical path is the first bright-field detection optical path 101.

[0100] In summary, by separating the bright-field optical axis and the vertical dark-field optical axis, each optical path is independently detected, avoiding the mutual influence between light sources and ensuring the detection accuracy of bright-field detection and dark-field detection. In addition, by setting two bright-field detection optical paths and one dark-field detection optical path 103, and setting three positions (the first bright-field position 104, the second bright-field position 105, and the dark-field position 106) to cooperate with two platforms, the first platform 14 can be moved to the first bright-field position 104 that will not be occupied by the second platform 19, so that the first platform 14 and the second platform 19 can start moving simultaneously, greatly improving the platform movement efficiency, making the transfer of the object to be measured more convenient. While performing bright-field detection on one object to be measured, dark-field detection can be performed on another object to be measured, that is, parallel detection of two objects to be measured can be realized, greatly improving the detection efficiency. At the same time, through the combined detection of bright-field and dark-field, various defects of the object to be measured can be accurately and comprehensively detected.

[0101] In a possible implementation, the detection system may include a basic optical path 100. The basic optical path 100 includes a first light source 1 for emitting a first light beam. The dark-field detection optical path 103 includes an adjustment module 22. S103 for performing dark-field detection on the i-th object to be measured at the dark-field position 106 based on the dark-field detection optical path 103 may specifically include S1031 - S1033.

[0102] S1031: Turn on the first light source 1 and use the first light beam as the dark-field detection light beam.

[0103] S1032: The adjustment module 22 is in the first state. Based on the dark-field detection optical path 103, the dark-field detection light beam is obliquely incident on the i-th object to be measured at the dark-field position 106 for dark-field detection.

[0104] S1033: The adjustment module 22 is in the second state. Based on the dark-field detection optical path 103, the dark-field detection light beam is vertically incident on the i-th object to be measured at the dark-field position 106 for dark-field detection.

[0105] Specifically, refer to Figure 1aAs shown, the first light source 1 can be turned on, and the first light beam emitted by the first light source 1 can be used as a dark-field detection light beam. The adjustment module 22 is respectively in the first state and the second state, so that the dark-field detection light beam can be obliquely incident on the surface of the object to be measured and vertically incident on the surface of the object to be measured. Among them, the execution order of S1032 and S1033 is not limited. S1032 can be executed first and then S1033, or S1033 can be executed first and then S1032.

[0106] As an example, when performing dark-field detection on the i-th object to be measured, the dark-field detection light beam can be obliquely incident on the surface of the object to be measured, and each position on the surface of the object to be measured can be traversed to realize the inclined dark-field detection of each position. Then, the dark-field detection light beam can be vertically incident on the surface of the object to be measured, and each position can be traversed to perform vertical dark-field detection. In this way, accurate detection of both convex defects and concave defects on the surface of the object to be measured can be achieved.

[0107] In a possible implementation manner, the detection system includes a first scanning optical path 201 and a second scanning optical path 202; the first bright-field position 104 is located on the light-emitting side of the first scanning optical path 201, and the second bright-field position 105 is located on the light-emitting side of the second scanning optical path 202; while S103 performs dark-field detection on the i-th object to be measured at the dark-field position 106 through the dark-field detection light beam based on the dark-field detection optical path 103, it performs bright-field detection on the (i + 1)-th object to be measured at the target position based on the target optical path, specifically including S1034.

[0108] S1034, while performing dark-field detection on the i-th object to be measured at the dark-field position 106 through the dark-field detection light beam based on the dark-field detection optical path 103, performs bright-field detection on the (i + 1)-th object to be measured at the target position based on the target optical path, and performs scanning processing on the (i + 1)-th object to be measured at the target position through the target scanning light beam based on the target scanning optical path.

[0109] Specifically, two scanning optical paths can be added to the detection system, namely the first scanning optical path 201 and the second scanning optical path 202. The scanning optical path is mainly used for scanning and processing defects. The scanning optical path can include a shaping module and at least one mirror, etc., for improving the beam shape and propagation direction. The optical power of the light beam in the scanning optical path can be relatively small to avoid scanning explosion.

[0110] The target scanning optical path can be the first scanning optical path 201 or the second scanning optical path 202. The first bright field position 104 is located on the light output side of the first scanning optical path 201, and the second bright field position 105 is located on the light output side of the second scanning optical path 202. That is to say, the target scanning optical path can be any one of the two scanning optical paths. When the target position is the first bright field position 104, the target scanning optical path is the first scanning optical path 201. When the target position is the second bright field position 105, the target scanning optical path is the second scanning optical path 202.

[0111] Reference Figure 4 As shown, the i-th object to be measured, i.e., Wafer II, is placed on the second platform 19. The second platform 19 is located at the dark field position 106. The (i + 1)-th object to be measured, i.e., Wafer III, is placed on the first platform 14. The first platform 14 is located at the first bright field position 104. At this time, the target position is the first bright field position 104, the target optical path is the first bright field detection optical path 101, and the target scanning optical path is the first scanning optical path 201. While performing dark field detection on Wafer II, the first scanning optical path 201 can be used to perform scanning processing on Wafer III, and the first bright field detection optical path 101 can be used to perform scanning processing on Wafer III.

[0112] In this way, by performing defect scanning processing on the object to be measured before dark field detection, the positions of various defects can be known, which is convenient for subsequent corresponding processing of defects of different sizes during dark field detection. For example, for large-sized defects, the position where the large-sized defects are located is skipped during dark field detection without performing dark field detection, thereby improving the detection accuracy. At this time, in the present application, defect scanning processing is performed while performing bright field detection, which is executed in parallel without waiting for the defect scanning processing to end before performing bright field detection, greatly improving the detection efficiency.

[0113] In summary, by separating the bright-field optical axis and the vertical dark-field optical axis, each optical path is independently detected, avoiding the mutual influence between light sources and ensuring the detection accuracy of bright-field detection and dark-field detection. In addition, by setting two bright-field detection optical paths and one dark-field detection optical path 103, and setting three positions (the first bright-field position 104, the second bright-field position 105, and the dark-field position 106) to cooperate with two platforms, the first platform 14 can be moved to the first bright-field position 104 that will not be occupied by the second platform 19, so that the first platform 14 and the second platform 19 can start moving simultaneously, greatly improving the platform movement efficiency and making the transfer of the object to be measured more convenient. While performing bright-field detection and scanning processing on one object to be measured at one bright-field position, dark-field detection can be performed on another object to be measured at the dark-field position, that is, parallel detection of two objects to be measured can be achieved, greatly improving the detection efficiency. At the same time, through the cooperation of bright-field, scanning processing, and dark-field detection, various defects of the object to be measured can be accurately and comprehensively detected, and the situation of large defects being scanned and exploded can be avoided.

[0114] In addition, for a single object to be measured, after bright-field detection, dark-field detection, and scanning processing are completed, the corresponding results can be fused to obtain the final detection result. Since the algorithm processing time after image acquisition is positively correlated with the number of defects and the surface roughness of the object to be measured. The more particles there are and the rougher the surface of the object to be measured, the longer the algorithm processing time, which affects the machine productivity. Therefore, the software architecture can be reconfigured to make the double-station movement time and the image processing time fully parallel, and unique labels can also be attached to the bright-field detection results, dark-field detection results, and defect scanning results of each object to be measured for distinction, so as to maximize the detection productivity of the object to be measured on the premise of ensuring the detection sensitivity of the machine.

[0115] In a possible implementation manner, the detection system may include a basic optical path 100 and a switching module. The basic optical path 100 may include a first light source 1 and a first beam splitting module 5; before performing dark-field detection on the i-th object to be measured at the dark-field position 106 through the dark-field detection beam based on the dark-field detection optical path 103, performing bright-field detection on the (i + 1)-th object to be measured at the target position based on the target optical path, and performing scanning processing on the (i + 1)-th object to be measured at the target position through the target scanning beam based on the target scanning optical path, S201 may further be included.

[0116] S201: Turn on the first light source 1, and through the switching module and the first beam splitting module 5, divide the first beam emitted by the first light source 1 into a dark-field detection beam incident on the dark-field detection optical path 103 and a target scanning beam incident on the target scanning optical path.

[0117] Specifically, when the dark-field detection optical path 103 and the scanning optical path share the same light source, i.e., the first light source 1, during detection, the first light source 1 can be turned on. After the first light beam emitted by the first light source 1 passes through the first beam splitting module 5, a dark-field detection light beam and a target scanning light beam are obtained. The dark-field detection light beam continues to propagate along the dark-field detection optical path 103, and the target scanning light beam propagates along the target scanning optical path.

[0118] In summary, by sharing the same light source, i.e., the first light source 1, for defect scanning processing and dark-field detection, the optical path cost can be saved, and by using the switching module to switch the scanning optical path, the optical path switching can be accurately and efficiently realized.

[0119] In a possible implementation, the detection system may include a basic optical path 100, a switching module, and a second light source 26. The basic optical path 100 may include a first light source 1 and a first beam splitting module 5; while performing dark-field detection on the i-th object to be measured at the dark-field position 106 through the dark-field detection light beam based on the dark-field detection optical path 103, performing bright-field detection on the (i + 1)-th object to be measured at the target position based on the target optical path, and before performing scanning processing on the (i + 1)-th object to be measured at the target position through the target scanning light beam based on the target scanning optical path, the method further includes S202 - S203.

[0120] S202: Through the first beam splitting module 5, the first light beam emitted by the first light source 1 is split into a redundant light beam and a dark-field detection light beam incident on the dark-field detection optical path 103.

[0121] S203: Turn on the second light source 26, and through the switching module, make the target scanning light beam emitted by the second light source 26 incident on the target scanning optical path.

[0122] Specifically, independent light sources can be provided for both the dark-field detection optical path 103 and the scanning optical path. During defect detection, the first light source 1 can be turned on. The first light beam emitted by the first light source 1 is split into a redundant light beam and a dark-field detection light beam after passing through the first beam splitting module 5.

[0123] Turn on the second light source 26, and use the first scanning light beam emitted by the second light source 26 as the target scanning light beam. Moreover, through the switching module, make the target scanning light beam incident on the target scanning optical path, thereby realizing the parallel execution of scanning processing and dark-field detection. Among them, the order of S202 and S203 is not limited, and the two can be executed simultaneously.

[0124] In summary, by providing an independent light source for the scanning optical path, the adjustment of the optical power of the scanning light beam is more flexible, not limited by the first light source 1, and the optical power requirement for the first light source 1 is reduced. The first light source 1 can select a light source with a smaller optical power, reducing the light source cost.

[0125] In a possible implementation, the detection system may include a basic optical path 100, a second light source 26, and a third light source 36. The basic optical path 100 may include a first light source 1 and a first beam splitting module 5; while performing dark field detection on the i-th object to be measured at the dark field position 106 through the dark field detection beam based on the dark field detection optical path 103, performing bright field detection on the (i + 1)-th object to be measured at the target position based on the target optical path, and before performing scanning processing on the (i + 1)-th object to be measured at the target position through the target scanning beam based on the target scanning optical path, the method may further include S204 - S206.

[0126] S204, through the first beam splitting module 5, split the first beam emitted by the first light source 1 into a redundant beam and a dark field detection beam incident on the dark field detection optical path 103.

[0127] S205, determine the target light source based on the target scanning optical path.

[0128] S206, turn on the target light source, use the beam emitted by the target light source as the target scanning beam, and make the target scanning beam incident on the target scanning optical path.

[0129] To further improve the freedom of adjusting the optical power of the beam, an independent light source may be set for each scanning optical path, that is, a second light source 26 is set for the first scanning optical path 201, and a third light source 36 is set for the second scanning optical path 202. The target light source may be the second light source 26 or the third light source 36.

[0130] Turn on the first light source 1, and the first beam emitted by the first light source 1 is divided by the first beam splitting module 5 into a redundant beam and a dark field detection beam. When the target scanning optical path is the first scanning optical path 201, the target light source is the second light source 26 corresponding to the first scanning optical path 201. When the target scanning optical path is the second scanning optical path 202, the target light source is the third light source 36 corresponding to the second scanning optical path 202. Turn on the target light source, use the beam emitted by the target light source as the target scanning beam, and make the target scanning beam incident on the target scanning optical path.

[0131] Reference Figure 5 As shown, the wafer III is located on the first platform 14, the target scanning optical path is the first scanning optical path 201, the target light source is the second light source 26. Turn on the first light source 1 and the second light source 26, use the beam emitted by the first light source 1 to perform dark field detection on the wafer II, and use the beam emitted by the second light source 26 to perform scanning processing on the wafer III.

[0132] In this way, an independent light source is set for each optical path, the optical power of the beam in each optical path can be independently adjusted without mutual influence, the adjustment of the optical power is more convenient and flexible, and the defect scanning, bright field detection, and dark field detection will all be more accurate.

[0133] In a possible implementation, in the defect scan result obtained after the scanning process of the i-th object to be measured is completed, it includes the defect positions of each defect on the surface of the i-th object to be measured and the light intensity of each defect. Before performing dark-field detection on the i-th object to be measured at the dark-field position 106 through the dark-field detection light path 103 in S103, the method further includes S301 of determining the defect category to which each defect belongs based on the light intensity; different defect categories correspond to different light intensity ranges; S104 of performing dark-field detection on the i-th object to be measured at the dark-field position 106 through the dark-field detection light path 103 with the dark-field detection beam can be specifically S401 - S402.

[0134] S401, traversing each position on the surface of the i-th object to be measured through the dark-field detection beam based on the dark-field detection light path 103 for dark-field detection.

[0135] S402, when performing dark-field detection on the target defect located at the target defect position, defect-detecting the target defect through the dark-field detection beam with the target optical power; the target optical power is determined based on the defect category to which the target defect belongs.

[0136] Specifically, the defect scan result of the i-th object to be measured may include the defect positions of each defect and the light intensity corresponding to each defect, that is to say, when performing defect scanning, the detection system can record the location where each defect is located and the light intensity value at the defect.

[0137] The defect category can be divided based on the size of the defect. The defect categories are, for example, large-size defects and small-size defects. The defect types are, for example, particles, surface defects, slip-line defects, etc. The light intensity ranges corresponding to the same type but different categories of defects (large-size defects, small-size defects) are different. As an example, the light intensity range corresponding to defect category one is X1~X2, and the light intensity range corresponding to defect category two is X3~X4. For a certain defect, the light intensity at the defect is compared with the light intensity range to determine the defect category corresponding to the defect. As an example, a large-size defect can be a defect with a size greater than 500 nm.

[0138] Then, when performing defect detection in S103, corresponding processing can be performed based on different defect categories. The dark-field detection beam can traverse each position on the surface of the i-th object to be measured. For example, the platform carrying the i-th object to be measured can drive the object to be measured to move, so that the dark-field detection beam irradiates different positions of the object to be measured, thereby realizing the traversal of each defect.

[0139] The target defect can be any defect on the object to be measured. The target defect position can be understood as the specific position of the target defect on the surface of the object to be measured. For example, it can be represented by horizontal and vertical coordinates. When traversing to the target defect, the corresponding target optical power can be determined based on the defect category to which the target defect belongs. The target optical power is the optical power of the dark-field detection beam when performing dark-field detection on the target defect. The optical powers of the dark-field detection beams corresponding to different defect categories are different.

[0140] In summary, for defects belonging to different categories, selecting the optical power of the matching dark-field detection beam for dark-field detection can achieve targeted detection of various defects, thereby improving the accuracy of the final detection result.

[0141] In a possible implementation, the optical power of the target scanning beam is less than the optical power of the dark-field detection beam; when the defect category to which the target defect belongs is the first defect category, the target optical power is the first value; when the defect category to which the target defect belongs is the second defect category, the target optical power is the second value; the minimum value of the first light intensity range corresponding to the first defect category is greater than the maximum value of the second light intensity range corresponding to the second defect category; the first value is less than the second value.

[0142] Specifically, the optical power of the target scanning beam required for defect scanning processing can be less than the optical power of the dark-field detection beam during defect detection. Defect scanning is mainly to identify large-size defects using a target scanning beam with a small optical power to avoid the situation where the defect is exploded by excessive optical power, such as a large particle defect being exploded, thereby contaminating the object to be measured. During dark-field detection, it is mainly to identify small-size defects using a dark-field detection beam with a large optical power.

[0143] The first defect category can also be any defect category. The light intensity range corresponding to the first defect category can be denoted as the first light intensity range, and the light intensity range corresponding to the second defect category can be denoted as the second light intensity range. The minimum value of the first light intensity range is greater than the maximum value of the second light intensity range, that is, the light intensities in the first light intensity range are greater than the light intensities in the second light intensity range.

[0144] Since during the defect scanning process, the light intensity corresponding to large-size defects is large and the light intensity corresponding to small-size defects is small, the first defect category represents large-size defects, such as large particle defects, and the second defect category represents small-size defects, such as small particle defects.

[0145] To avoid detonating large-sized defects during defect detection, when traversing to large-sized defects, i.e., the first defect category, the target optical power can adopt a smaller first value. Adopting a smaller optical power can avoid damaging large-sized defects and contaminating the object to be measured. When traversing to small-sized defects, i.e., the second defect category, the target optical power can adopt a larger second value to accurately detect smaller-sized defects.

[0146] In practical applications, when the target defect category is the first defect category, adopting a smaller first value for the target optical power can mean reducing the target optical power or setting the target optical power to 0, that is, not performing defect detection on large-sized defects. Reducing the target optical power can be achieved by opening and closing an Acoustic Optical Modulator (AOM) to lower the optical power. Setting the target optical power to 0 can also mean preventing the dark-field detection beam from entering the position where the large-sized defect is located.

[0147] In summary, by using appropriate optical powers to detect large-sized and small-sized defects during dark-field detection, it is possible to avoid detonating large-sized defects and accurately detect small-sized defects.

[0148] In a possible implementation, the dark-field detection optical path 103 further includes a switch. Using the dark-field detection beam with the target optical power to perform defect detection on the target defect can specifically be: when the target defect belongs to the second defect category, control the switch to be in the open state, and the dark-field detection beam passes through the switch to perform defect detection on the target defect; when the target defect belongs to the first defect category, control the switch to be in the closed state, and the dark-field detection beam is blocked by the third switch, and no defect detection is performed on the target defect.

[0149] Specifically, the switch 37 can be located in the dark-field detection optical path 103 to control whether the dark-field detection beam can enter the surface of the object to be measured. When the target defect belongs to the second defect category, it indicates that the target defect is a small-sized defect, and dark-field detection is mainly for detecting such defects. Therefore, the switch 37 can be controlled to be in the open state so that the dark-field detection beam can pass through the switch 37 to detect the target defect on the surface of the object to be measured.

[0150] When the target defect belongs to the first defect category, it indicates that the target defect is a large-sized defect. Since it has been detected through defect scanning processing and to avoid detonation, there is no need to perform dark-field detection again. Therefore, the switch 37 can be controlled to be in the closed state, and the dark-field detection beam is blocked by the switch 37 and cannot continue to propagate backward, thus not performing defect detection on the target defect.

[0151] In other words, when performing defect detection on the object to be measured, if the dark-field detection beam is incident on the position where the large defect is located, the switch 37 is quickly turned off. After skipping the position where the large defect is located, the switch 37 is turned on again to continue the dark-field detection of the small defect.

[0152] In summary, by setting the switch 37 in the dark-field detection optical path 103, different optical powers can be conveniently used for dark-field detection of large-size defects and small-size defects by turning off the switch 37. The operation is convenient, the cost is low, and the explosion of large-size defects can be avoided to the greatest extent.

[0153] In this application, the scanning optical path can be a bright-field scanning optical path. In this case, the scanning optical path performs defect scanning in the manner of bright-field processing. The scanning optical path can also be an inclined dark-field scanning optical path. In this case, the scanning optical path performs defect scanning in the manner of inclined dark-field processing. Bright-field processing performs defect imaging through the reflected light on the surface of the object to be measured. Dark-field processing performs defect imaging using the scattered light on the surface of the object to be measured. Inclined dark-field processing means that the incident light is incident obliquely rather than perpendicularly to the surface of the object to be measured, and the collection channel is also set obliquely rather than along the normal direction of the surface of the object to be measured, that is, both the incident light and the collection channel are set non-normally. The dark-field detection optical path can include normal and / or inclined dark-field processing, that is, the incident light is incident vertically and / or obliquely on the surface of the object to be measured while the collection channel is set obliquely and / or normally to collect the scattered light of the object to be measured. Next, the optical paths during bright-field processing and dark-field processing will be introduced in detail.

[0154] In a possible implementation manner, when performing bright-field processing or dark-field processing, one or more collection channels can be set above the bright-field position or the dark-field position. For example, a collection channel can be set directly above, or a collection channel can be set obliquely above. When the scanning optical path is an inclined dark-field scanning optical path, the collection channel is set obliquely above the bright-field position rather than directly above. The collection channel is used to receive the beam from the upper surface of the object to be measured for imaging. One or more corresponding detectors are provided in the collection channel, and the detectors are used to perform imaging based on the beam.

[0155] The detector may include any suitable detector known in the art, such as a discrete photomultiplier tube (PMT), a charge-coupled device (CCD), a time delay integration (TDI), a complementary metal oxide semiconductor (CMOS) sensor, a PMT array, an electron bombardment CCD (EB-CCD), an electron-multiplying CCD (EM-CCD), an intensified photodiode, or an avalanche photodiode (APD) array.

[0156] In one possible implementation, during dark field processing (such as tilting the dark field scanning optical path or the dark field detection optical path), a detection system can be arranged at a suitable position diagonally above the bright field position or the dark field position. The detection system includes a collection channel and a corresponding detector. The number of detection systems can be one or two. When the number of detection systems is one, the detection system can collect and image the scattered light from the upper surface of the object to be measured, thereby realizing defect scanning or defect detection on the upper surface of the object to be measured. When the number of detection systems is two, the two detection systems can be arranged on both sides of the object to be measured, for example, they can be arranged symmetrically left and right, or asymmetrically.

[0157] In one possible implementation, when collecting scattered light during dark field processing, multiple detection systems can be arranged on the object to be measured. The detection system includes a collection channel and a corresponding detector. The multiple detection systems can be symmetrically distributed along the vertical line of the surface of the object to be measured and symmetric about the incident plane. Then, when the defects on the surface of the object to be measured are symmetric, the signals received by the two symmetric detection systems are the same. When the defects on the surface of the object to be measured have different geometric features, the signals received by the two symmetric detection systems are different, so that the geometric features of the defects can be determined. Of course, the multiple detection systems can also be asymmetrically distributed.

[0158] In one possible implementation, the collection channel can be a normal detection channel or an abnormal collection channel. The normal collection channel is that the detection channel is in the normal direction of the surface of the object to be measured. It can be considered that the normal collection channel is directly above the object to be measured. The abnormal collection channel is that the collection channel deviates from the normal direction of the surface of the object to be measured. It can be considered that the abnormal collection channel is diagonally above the object to be measured.

[0159] In one possible implementation, the light source mentioned in the present application may include any suitable light source, such as a laser, a continuous wave (CW) laser, or a pulsed laser. In addition, the light source may be configured to generate light of any suitable wavelength (e.g., about 355 nm, about 266 nm, or about 193 nm).

[0160] In one possible implementation, the collection channel may include a certain scattered light collector and some additional optical elements that may be coupled to the scattered light collector. The collector includes, but is not limited to, an objective lens for gathering at least a part of the light of the analyte sample. The additional optical elements may be, for example, one or more apertures, one or more lenses, one or more separators, one or more polarization elements, one or more filters, one or more reflective optical elements, and one or more refractive optical elements.

[0161] In one possible implementation, the platform (e.g., the first platform 14 or the second platform 19) may be an edge clamping chuck, a vacuum chuck, etc. One platform may support multiple analyte diameters (e.g., 300 mm and 450 mm) or a single analyte diameter.

[0162] In one possible implementation, the optical path may further include an axis coupled to the chuck and coupled to the positioning subsystem. The positioning subsystem may include various elements configured to rotate and / or translate the axis, such as motors, gears, etc. The axis may be coupled to the chuck in such a way that the rotation and / or translation of the axis causes the rotation and / or translation of the platform, thereby causing the rotation and / or translation of the analyte. The platform may translate the analyte in a spiral or X-Y manner or a certain combination of both as further described herein. In particular, in addition to the spiral scan described above, X-Y serpentine scan and RT-XY hybrid scan can both be used to translate the analyte relative to the illumination and collection optics.

[0163] In one possible implementation, the light beam emitted by the light source may be incident perpendicularly to the surface of the analyte or obliquely to the surface of the analyte. As an example, in the case of perpendicular incidence, multiple detection channels may be provided obliquely above the analyte to detect the reflected light from the surface of the analyte. In the case of oblique incidence, the multiple detection channels located obliquely above the analyte may detect the scattered light from the surface of the analyte.

[0164] In one possible implementation, for detecting the scattered light or reflected light from the surface of the analyte, its exit surface may be perpendicular to the incident surface of the light emitted by the light source or have an acute angle.

[0165] In a possible implementation, when scanning for defects using bright-field processing, a detection system can be set up to collect reflected light. When detecting defects using dark-field processing, a detection system can be set up to collect scattered light. In addition, during bright-field processing, the detection system located directly above the object to be measured can collect directly incident reflected light, and the detection system located obliquely above the object to be measured can collect obliquely incident reflected light. The detection system includes a collection channel and a corresponding detector.

[0166] In a possible implementation, for any optical path, such as a scanning optical path or a detection optical path, multiple light beams can be set to exit, so that the multiple light beams can be incident on the surface of the object to be measured at different angles. After being reflected or scattered by the surface of the object to be measured, signal light is obtained and collected using different detection systems. The detection system includes a collection channel and a corresponding detector. By providing multiple light beams incident on the object to be measured, defects of different sizes can be detected. When the incident angle between the light and the object to be measured is different, the sensitivity of defect scanning or defect detection is also different, thus meeting the user's requirements for various detection sensitivities. When the defect size is small, the sensitivity of defect detection or defect scanning can be appropriately increased to avoid missed judgments.

[0167] In a possible implementation, the light spot of the beam emitted by the light source after being shaped and irradiated on the surface of the object to be measured can be a point light spot or a line light spot. During dark-field processing, if there are defects at the illumination position, the defects will cause part of the light to be emitted upward at various angles in the form of scattered light. Therefore, multiple scattered light collection channels can be set at different positions to detect the scattered light intensity at different angles, and the defect information at the position of the light spot can be judged. It can be understood that by collecting signal light through multiple signal collection channels, the detection accuracy can be improved. The detection branch corresponding to each collection channel includes a detection lens group and a detector to achieve imaging collection of the signal light. When a line detector is used, the detection area is linear.

[0168] In a possible implementation, the beam emitted by the light source can be divided into multiple offset beams, and the phase characteristics between the multiple offset beams are adjusted so that they can be focused on the surface of the object to be measured simultaneously.

[0169] In a possible implementation, when collecting scattered light (for dark-field processing) or reflected light (for bright-field processing) from the surface of the object to be measured, a condenser with a large numerical aperture (NA) can be used for light collection, that is, the scattered light or reflected light enters the detector after passing through the large-NA objective lens. In addition, for the reflected light or scattered light, optical elements can be configured to distribute light of different wavelength bands to different collection channels.

[0170] In a possible implementation, when collecting the scattered light or reflected light from the surface of the object under test, the reflected light or scattered light can be spectroscopically processed and divided into two beams of light that enter different collection channels for defect imaging. In a possible implementation, the light beam emitted by the light source can be incident obliquely on the surface of the object under test. Of course, it can also be normally incident, and the choice can be based on the actual situation. When using the oblique dark-field scanning optical path for defect scanning, the light beam emitted by the light source is obliquely incident, and it should be noted that it will not be normally incident on the surface of the object under test.

[0171] In a possible implementation, the light scattered by the surface of the object under test can be collected and focused by a lens condenser and guided to a detector. As an example, the lens condenser can be ellipsoidal.

[0172] Next, a detailed description will be given on how to implement the movement of the first platform 14 and the second platform 19. Refer to Figure 7 As shown in the figure, which is a schematic diagram of a motion stage provided by an embodiment of the present application, the movement and rotation of the first platform 14 and the second platform 19 can be realized by the motion stage. The motion stage includes a moving plate 301 and a transmission mechanism 302. Among them, the first platform 13 is placed on one moving plate 301, and the second platform 19 is placed on another moving plate 301. The transmission mechanism 302 is an XY two-dimensional motion mechanism, and the transmission mechanism 302 can include a linear motor and a guide rail. The transmission mechanism 302 can also be completed by a lead screw or a conveyor belt for the movement of the first platform 14 and the second platform 19. The motion stage can realize X, Y, and R-axis movements, where X and Y represent an orthogonal coordinate system, and the R-axis represents rotation around the Z-axis. Combining Figure 1c To illustrate, the X and Y-axis movements can move the first platform 14 and the second platform 19 in the plane of the motion stage, realizing the switching of the first platform 14 between the first bright-field position 104 and the dark-field position 106, and the switching of the second platform 19 between the second bright-field position 105 and the dark-field position 106. The first platform 14 and the second platform 19 can respectively rotate around the R-axis on the moving plate 301. The coordinated movement of the X, Y, and R axes realizes spiral scanning (RT) or X-Y serpentine scanning or RT-XY hybrid scanning of the object under test at the first bright-field position 104, the second bright-field position 105, and the dark-field position 106.

[0173] The detection method provided by the present application can be applied to a detection system, and specifically, the computer subsystem can be used to control the detection system to realize the adjustment of the optical path, the movement of the platform, etc. The computer subsystem can include any suitable computer system known in the art. For example, the computer subsystem can take various forms, including a personal computer system, a mainframe computer system, a workstation, an image computer, a parallel processor, or any other device known in the art. Generally, the term "computer subsystem" can be widely defined as any device that includes one or more processors that execute instructions from a storage medium.

[0174] The various embodiments in this specification are described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the key point of each embodiment is to illustrate the differences from other embodiments. In particular, for the device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and for the relevant parts, reference can be made to the partial description of the method embodiments.

[0175] The above description is only a preferred embodiment of the present application. Although the present application has been disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present application by using the methods and technical contents disclosed above, or modify it into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the technical solution of the present application still fall within the scope of the protection of the technical solution of the present application.

Claims

1. A detection system, characterized in that: The detection system comprises a first bright field detection optical path, a second bright field detection optical path, a dark field detection optical path, a first platform and a second platform; The first platform and the second platform are both used to carry the object to be tested, the first platform switches between a first bright field position and a dark field position, and the second platform switches between a second bright field position and the dark field position; the first bright field position and the second bright field position are respectively located at the light exit side of the first bright field detection light path and the second bright field detection light path, and the dark field position is located at the light exit side of the dark field detection light path; While the dark field detection optical path is used to perform dark field detection on the i-th object to be detected in the dark field position, the target optical path is used to perform bright field detection on the i+1-th object to be detected in the target position; the target optical path is the first bright field detection optical path or the second bright field detection optical path, and the target position is the first bright field position or the second bright field position; i≥1.

2. The detection system according to claim 1, characterized in that: The detection system comprises a basic optical path, wherein the basic optical path comprises a first light source for emitting a first light beam; the dark field detection optical path comprises an adjustment module; When the adjustment module is in the first state, the dark field detection optical path is used to make the first light beam obliquely incident on the object to be detected to perform dark field detection; When the adjustment module is in the second state, the dark field detection optical path is used to make the first light beam vertically incident on the object to be detected to perform dark field detection.

3. The detection system according to claim 1, characterized in that: The detection system comprises a first scanning optical path and a second scanning optical path; the first bright field position is located at the light exit side of the first scanning optical path, and the second bright field position is located at the light exit side of the second scanning optical path; While the first bright field detection optical path is used to perform bright field detection on the i-th object to be detected located at the first bright field position, the first scanning optical path is used to perform scanning processing on the i-th object to be detected located at the first bright field position; While the second bright field detection optical path is used to perform bright field detection on the i-th object to be detected located at the second bright field position, the second scanning optical path is used to perform scanning processing on the i-th object to be detected located at the second bright field position.

4. The detection system according to claim 3, characterized in that: The detection system comprises a basic optical path and a switching module, wherein the basic optical path comprises a first light source and a first light splitting module; The first beam splitting module is used to split the first light beam emitted by the first light source into a dark field detection beam incident on the dark field detection light path, and a target scanning beam incident on the first scanning light path or the second scanning light path; the switching module is used to switch the scanning beam between the first scanning light path and the second scanning light path.

5. The detection system according to claim 3, characterized in that: The detection system comprises a basic optical path, the switching module and a second light source, wherein the basic optical path comprises a first light source and a first light splitting module; The first light splitting module is used for splitting the first light beam emitted by the first light source into a redundant light beam and a dark field detection light beam incident on the dark field detection light path; The second light source is used to emit a first scanning light beam, and the switching module is used to switch the first scanning light beam between the first scanning light path and the second scanning light path.

6. The detection system according to claim 5, characterized in that: The basic optical path further comprises a light absorbing module located at a side of the first light splitting module emitting the redundant light beam, and the light absorbing module is used to absorb the redundant light beam.

7. The detection system according to claim 5, characterized in that: The optical power of the first light source is greater than the optical power of the second light source.

8. The detection system according to claim 3, characterized in that: The detection system comprises a basic optical path, a second light source and a third light source, wherein the basic optical path comprises a first light source and a first light splitting module; The first light splitting module is used for splitting the first light beam emitted by the first light source into a redundant light beam and a dark field detection light beam incident on the dark field detection light path; The second light source is used to emit a first scanning light beam incident on the first scanning light path; The third light source is used to emit a second scanning light beam incident on the second scanning light path.

9. The detection system according to any one of claims 1 to 8, characterized in that: The dark field detection optical path also includes a switch; When the switch is in an on state, the switch is used to enable the dark field detection light beam to perform dark field detection on a target defect belonging to a second defect category on the surface of the object to be detected; When the switch is in the off state, the switch is used to prevent the dark field detection beam from performing dark field detection on target defects belonging to the first defect category on the surface of the object to be tested; in the defect scanning result obtained after the scanning process of the i-th object to be tested, the minimum value of the first light intensity range corresponding to the first defect category is greater than the maximum value of the second light intensity range corresponding to the second defect category.

10. A detection method, characterized in that: Applied to the detection system according to any one of claims 1 to 9, the method comprises: Moving the i-th object to be tested from an initial bright field position to the dark field position; the initial bright field position is the first bright field position or the second bright field position, and the i-th object to be tested has completed bright field detection at the initial bright field position; The (i+1)th object to be tested is located at the target bright field position; the target bright field position is different from the initial bright field position; While performing dark field detection on the i-th object to be detected at the dark field position through a dark field detection beam based on the dark field detection optical path, performing bright field detection on the i+1-th object to be detected at the target position based on the target optical path.

11. The detection method according to claim 10, characterized in that: The detection system comprises a basic optical path, wherein the basic optical path comprises a first light source for emitting a first light beam; the dark field detection optical path comprises an adjustment module; and the dark field detection of the i-th object to be detected in the dark field position by the dark field detection light beam based on the dark field detection optical path comprises: Turning on the first light source and using the first light beam as the dark field detection light beam; The adjustment module is in a first state, and based on the dark field detection optical path, the dark field detection light beam is obliquely incident on the i-th object to be detected in the dark field position to perform dark field detection; The adjustment module is in a second state, and based on the dark field detection optical path, the dark field detection light beam is vertically incident on the i-th object to be detected in the dark field position to perform dark field detection.

12. The detection method according to claim 10, characterized in that: The detection system comprises a first scanning optical path and a second scanning optical path; the first bright field position is located at the light exit side of the first scanning optical path, and the second bright field position is located at the light exit side of the second scanning optical path; while performing dark field detection on the i-th object to be detected at the dark field position through a dark field detection beam based on the dark field detection optical path, performing bright field detection on the i+1-th object to be detected at the target position based on the target optical path, comprising: While performing dark field detection on the i-th object to be detected at the dark field position based on the dark field detection optical path through the dark field detection light beam, performing bright field detection on the i+1-th object to be detected at the target position based on the target optical path, and performing scanning processing on the i+1-th object to be detected at the target position through the target scanning light path through the target scanning light beam; The target scanning light path is the first scanning light path or the second scanning light path, the first bright field is located at the light exit side of the first scanning light path, and the second bright field is located at the light exit side of the second scanning light path.

13. The detection method according to claim 12, characterized in that: The detection system comprises a basic optical path and a switching module, wherein the basic optical path comprises a first light source and a first light splitting module; while performing dark field detection on the i-th object to be detected at the dark field position based on the dark field detection optical path through the dark field detection beam, performing bright field detection on the i+1-th object to be detected at the target position based on the target optical path, and scanning and processing the i+1-th object to be detected at the target position based on the target scanning optical path through the target scanning beam, the method further comprises: The first light source is turned on, and the first light beam emitted by the first light source is split into the dark field detection light beam incident on the dark field detection light path and the target scanning light beam incident on the target scanning light path through the switching module and the first light splitting module.

14. The detection method according to claim 12, characterized in that: The detection system comprises a basic optical path, the switching module and a second light source, the basic optical path comprises a first light source and a first spectroscopic module; while performing dark field detection on the i-th object to be detected in the dark field position based on the dark field detection optical path through the dark field detection light beam, performing bright field detection on the i+1-th object to be detected in the target position based on the target optical path, and scanning and processing the i+1-th object to be detected in the target position based on the target scanning optical path through the target scanning light beam, the method further comprises: By using the first light splitting module, the first light beam emitted by the first light source is split into a redundant light beam and the dark field detection light beam incident on the dark field detection light path; The second light source is turned on, and the target scanning light beam emitted by the second light source is made incident on the target scanning light path through the switching module.

15. The detection method according to claim 12, characterized in that: The detection system comprises a basic optical path, a second light source and a third light source, wherein the basic optical path comprises a first light source and a first spectroscopic module; while performing dark field detection on the i-th object to be detected at the dark field position based on the dark field detection optical path through the dark field detection light beam, performing bright field detection on the i+1-th object to be detected at the target position based on the target optical path, and scanning and processing the i+1-th object to be detected at the target position based on the target scanning optical path through the target scanning light beam, the method further comprises: By using the first light splitting module, the first light beam emitted by the first light source is split into a redundant light beam and the dark field detection light beam incident on the dark field detection light path; Determine a target light source based on the target scanning light path; the target light source is the second light source or the third light source; The target light source is turned on, the light beam emitted by the target light source is used as the target scanning light beam, and the target scanning light beam is made incident on the target scanning light path.

16. The detection method according to claim 12, characterized in that: The defect scanning result obtained by completing the scanning process on the i-th object to be tested includes the defect position of each defect on the surface of the i-th object to be tested and the light intensity of each defect; Before performing dark field detection on the i-th object to be detected in the dark field position through the dark field detection light beam based on the dark field detection optical path, the method further includes: Determining the defect category to which each defect belongs based on the light intensity; different defect categories correspond to different light intensity ranges; The performing dark field detection on the i-th object to be detected in the dark field position by using the dark field detection light beam based on the dark field detection optical path comprises: Based on the dark field detection optical path, the dark field detection light beam traverses each position on the surface of the i-th object to be detected to perform dark field detection; When performing dark field detection on a target defect located at a target defect position, the target defect is detected by using the dark field detection light beam having a target optical power; the target optical power is determined based on a defect category to which the target defect belongs.

17. The detection method according to claim 16, characterized in that: The optical power of the target scanning beam is less than the optical power of the dark field detection beam; when the defect category to which the target defect belongs is the first defect category, the target optical power is a first value; when the defect category to which the target defect belongs is the second defect category, the target optical power is a second value; The minimum value of the first light intensity range corresponding to the first defect category is greater than the maximum value of the second light intensity range corresponding to the second defect category; and the first value is smaller than the second value.

18. The detection method according to claim 17, characterized in that: The dark field detection optical path further includes a switch; and the defect detection of the target defect by the dark field detection light beam having the target optical power includes: When the target defect belongs to the second defect category, the switch is controlled to be in an open state, and the dark field detection light beam passes through the switch to perform defect detection on the target defect; When the target defect belongs to the first defect category, the switch is controlled to be in a closed state, the dark field detection beam is blocked by the switch, and defect detection is not performed on the target defect.

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