Defect detection system and defect detection method using dark field imaging

Abstract

This invention provides a defect detection method using dark-field imaging. First, a light source transmits a point-shaped light signal through a first lens. The point-shaped light signal is collimated by the first lens to generate a collimated light signal, which is obliquely incident on the surface of the sample under test. Second, by adjusting the dark-field incident angle and / or adjusting the azimuth angle of the collimated light signal on the sample under test, a dark-field image of the sample surface is obtained for detecting defects on the device surface. This invention also provides a defect detection system using dark-field imaging, comprising: a light source, a stage, a light transmission module, an imaging device, and a computer system, used to adjust the incident angle and azimuth angle in dark-field imaging and acquire defect information on the sample surface. Therefore, by adjusting the incident angle and azimuth angle of dark-field imaging from multiple angles, this invention not only avoids interference from the angular diffraction characteristics of the sample under test on dark-field imaging but also meets the diverse detection needs of the sample.

Description

Technical Field

[0001] This invention relates to the field of optical systems and optical signal detection, and in particular to a defect detection system and method for dark-field imaging. Background Technology

[0002] Dark-field illumination imaging is a commonly used imaging technique for semiconductor AOI defect detection. Dark-field illumination involves projecting an illumination beam onto the sample surface at a very large incident angle, causing specularly reflected light to be reflected at an extremely large angle, preventing it from entering the objective lens for imaging. The resulting image is entirely black in grayscale. However, if surface defects exist, some of the diffusely reflected light from these defects enters the objective lens for imaging. These defects appear as bright images against the dark field of view, significantly improving the signal-to-noise ratio of the defect imaging. Dark-field imaging thus offers better detection performance in defect detection applications. However, for certain specific optical structures, dark-field imaging is ineffective or even impossible.

[0003] Therefore, how to provide a dark-field imaging defect detection system and method for multi-angle dark-field imaging of the sample under test, so as to avoid the adverse effects of angular diffraction characteristics, has become one of the technical problems that urgently need to be solved by those skilled in the art.

[0004] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a defect detection system and method for dark field imaging, which solves the problem that the angular diffraction characteristics of the sample under test cannot be resolved in the prior art, thus causing adverse effects on dark field imaging.

[0006] To achieve the above and other related objectives, the present invention provides a dark-field imaging defect detection system, comprising: a light source, a stage, a light transmission module, an imaging device, and a computer system; the light source is obliquely incident on the sample to be tested; the stage is used to support the sample to be tested; the light transmission module is used to guide the light emitted by the light source to the sample to be tested, and to collect the light scattered from the sample to be tested and transmit it to the imaging device; the imaging device acquires an image of the surface of the sample to be tested based on the light scattered from the surface of the sample to be tested.

[0007] The computer system is used to send angle transformation commands and output defect information of the sample under test based on the image data acquired by the imaging device.

[0008] Optionally, the light transmission module includes a first lens, which is disposed between the light source and the sample to be tested, and the light source is modulated into parallel light after passing through the first lens and incident on the surface of the sample to be tested.

[0009] Alternatively, the focusing position of the light source at the rear focal plane of the first lens can be changed to alter the incident angle for defect detection.

[0010] Alternatively, the step of changing the focusing position of the light source at the rear focal plane of the first lens includes:

[0011] The light source is driven to move in the same plane parallel to the rear focal plane of the first lens.

[0012] Alternatively, the step of changing the focusing position of the light source at the rear focal plane of the first lens includes:

[0013] The optical transmission module further includes a first reflector, which is disposed between the light source and the first lens to adjust the reflection angle of the light source after passing through the first reflector.

[0014] Alternatively, the adjustment range of the incident angle is: ,in, This represents the minimum incident angle of the detection system. This indicates the numerical aperture of the first lens. This represents the spatial refractive index between the first lens and the sample under test.

[0015] Alternatively, defect detection can be performed by changing the azimuth angle, where the azimuth angle is the angle between the vertical projection of the obliquely incident light beam onto the surface of the sample under test and a preset reference direction of the surface of the sample under test.

[0016] Alternatively, the step of changing the azimuth angle includes: controlling the first lens to rotate around the normal of the sample under test via the computer system.

[0017] Alternatively, the step of changing the azimuth angle may further include: driving the platform to rotate around the normal of the sample under test via the computer system.

[0018] Alternatively, the step of changing the azimuth angle further includes:

[0019] A compensation lens is provided in the imaging optical path of the detection system, and the compensation lens is positioned between the sample to be tested and the imaging device; the angular deviation is compensated by rotating the compensation lens.

[0020] To achieve the above and other related objectives, the present invention also provides a defect detection method for dark-field imaging, the method comprising: providing an oblique incident light source; modulating the illumination light emitted by the light source into parallel light and guiding it to the surface of the sample to be tested; scanning and acquiring images of the surface of the sample to be tested at multiple incident angles and azimuth angles; and determining defect information of at least one periodic angular diffraction characteristic structure on the surface of the sample to be tested based on the acquired multiple images of the surface of the sample to be tested.

[0021] As described above, the dark-field imaging defect detection system and method of the present invention, when detecting the sample to be tested, can not only avoid the interference of the angle diffraction characteristics of the sample to be tested on the dark-field imaging by adjusting the dark-field incident angle and azimuth angle from multiple angles, but also meet the diverse detection needs of the sample to be tested. Attached Figure Description

[0022] Figure 1 The diagram shown is a first structural schematic of the defect detection system for dark-field imaging according to the present invention.

[0023] Figure 2 The diagram shown is a second structural schematic of the defect detection system for dark-field imaging according to the present invention.

[0024] Figure 3 This diagram illustrates the first method for generating the azimuth angle in dark-field imaging according to the present invention.

[0025] Figure 4 This diagram illustrates a second method for generating the azimuth angle in dark-field imaging according to the present invention.

[0026] Figure 5 The diagram shown is a third structural schematic of the dark-field imaging defect detection system of the present invention.

[0027] Figure 6 The diagram shown is a fourth structural schematic of the dark-field imaging defect detection system of the present invention.

[0028] Figure 7 The diagram shown is a rotating schematic of the incident light path of the present invention.

[0029] Figure 8 This is a schematic diagram of the fifth structure of the dark-field imaging defect detection system of the present invention.

[0030] Figure 9 The diagram shown is a sixth structural schematic of the dark-field imaging defect detection system of the present invention.

[0031] Figure 10 This is a schematic diagram of the seventh structure of the dark-field imaging defect detection system of the present invention.

[0032] Figure 11 The diagram shown illustrates the angle compensation of the imaging using the compensation lens of this invention.

[0033] Component designation explanation

[0034] 1. Incident light path

[0035] 1a light source

[0036] 1b First Lens

[0037] 1c First reflecting mirror

[0038] 1d second lens

[0039] 1e collimating lens

[0040] 1f focusing lens

[0041] 1g second reflecting mirror

[0042] 2. Light source switching device

[0043] 3 Samples to be tested

[0044] 4 support platforms

[0045] 5 Imaging Optical Path

[0046] 5a imaging device

[0047] 5b imaging lens

[0048] 5c objective lens

[0049] 5D compensating lens

[0050] 6 Computer Systems

[0051] 7 lighting arms Detailed Implementation

[0052] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0053] Please see Figures 1-11 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. The illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0054] The increasing complexity and miniaturization of semiconductor manufacturing processes pose significant challenges to optical defect detection systems for semiconductors. The main challenge for dark-field imaging systems lies in the periodic optical structures on the surface of the sample under test, especially grating devices with pronounced angular diffraction characteristics. When the diffracted light signal enters the objective lens for imaging, it significantly impacts the dark-field imaging effect, affecting the signal-to-noise ratio of dark-field defect detection.

[0055] Considering that diffracted light signals are mainly affected by the periodicity and orientation of the periodic optical structures on the device surface, the impact of diffraction on optical imaging can be significantly reduced by continuously adjusting the incident angle and azimuth angle of the light signal received by a specific optical structure. This is especially true for dark-field imaging. When using the dark-field imaging principle for dark-field defect detection, providing a scheme for variable incident angle and azimuth angle for dark-field illumination can meet the increasingly diverse and precise needs of dark-field detection.

[0056] Therefore, the present invention provides a defect detection system and method for dark-field imaging, the specific technical solution of which is as follows:

[0057] As one example, such as Figure 1 As shown, this embodiment provides a dark-field imaging defect detection system, including: a light source, a stage, an optical transmission module, an imaging device, and a computer system 6; wherein, the transmission path from the light source to the sample to be tested on the stage via the optical transmission module is the incident light path of the dark-field imaging defect detection system, that is, the optical devices in the incident light path are arranged between the light source and the sample to be tested. As an example, the incident light path of this system includes: a light source 1a, a light source switching device 2, a first lens 1b, a collimating lens 1e, and a focusing lens 1f, wherein the first lens 1b, the light source switching device 2, the collimating lens 1e, and the focusing lens 1f belong to the optical transmission module; wherein, the light source 1a can be a high-intensity modulated laser or an incoherent light source. At the same time, the light source 1a can be a separate dark-field light source, and when this system is used in combination with a bright-field detection system, the light source 1a can also be a common light source for both the bright-field and dark-field systems.

[0058] Light source 1a is mounted on light source switching device 2. Light source switching device 2 may include a motor and a light source adapter plate 2. When the motor receives a switching command from computer system 6, it moves light source 1a within the plane of the light source adapter plate 2. Those skilled in the art will understand that the light source adapter plate 2 has multiple light source entrance holes or fiber optic interfaces, with different entrance holes or fiber optic interfaces representing different incident angles. The plane of the light source adapter plate 2 is a fixed horizontal plane parallel to the rear focal plane of the first lens 1b. By changing the focusing position of light source 1a at the rear focal plane of the first lens 1b, the incident angle can be changed for defect detection. In addition to the aforementioned scheme, the light source switching device 2 can also be manually adjusted to achieve the adjustment of the incident angle.

[0059] In one example, the first lens 1b is configured as a collimating lens. After passing through the first lens 1b, the light source 1a is modulated into parallel light and incident on the surface of the sample to be tested, which is more conducive to the detection of the periodic grating structure on the surface of the sample 3.

[0060] The transmission path from the scattered light signal of the sample under test on the stage to the imaging device is the imaging optical path of the dark-field imaging defect detection system. As an example, the imaging optical path 5 includes: an imaging device 5a, an imaging lens 5b, and an objective lens 5c. The imaging lens 5b and objective lens 5c belong to the light transmission module. The light scattered from the surface of the sample under test is collected by the objective lens 5c and transmitted to the imaging device through the imaging lens 5b. The imaging device 5a uses an optical camera, such as an area array or line array camera, to acquire images of the surface of the sample under test 3.

[0061] The support platform 4 is used to support the sample 3 to be tested; the support platform 4 can be a support device based on vacuum adsorption or air flotation principle, which supports the sample 3 to be tested to translate or move along the z-axis in the working area of ​​the system to meet the various needs of the sample 3 to be tested in the detection process.

[0062] Computer system 6, as part of the defect detection system, can send angle transformation commands and output defect information of the sample under test based on the image data acquired by the imaging device. The angle transformation commands include azimuth angle transformation and incident angle transformation. Computer system 6 includes a motion control module, which controls the platform 4 to translate in the horizontal plane or move along the z-axis in a Cartesian coordinate system. It can also send switching commands to the light source switching device 2 to switch between different incident angles, and control the motors in the defect detection system to rotate or translate, thereby realizing the various functions of the detection system. In practical applications, motors are configured as needed to achieve rotation or translation of the light source, platform, and incident light path.

[0063] Figure 2This is another example of an incident angle transformation in a dark-field imaging defect detection system. In this example, the incident light path 1 includes a light source 1a, a first lens 1b, a first reflector 1c, and a second lens 1d. The first lens 1b, the first reflector 1c, and the second lens 1d belong to the light transmission module. The incident light is focused by the second lens 1d onto the focal plane (shown by the dashed line) of the first lens 1b to further increase the intensity of the light signal. Then, it is modulated by the first lens 1b into parallel light that is obliquely incident on the surface of the sample 3 to be tested. In this embodiment, the first reflecting mirror 1c is positioned between the light source 1a and the first lens 1b. It can be a galvanometer, acousto-optic deflector, electro-optic deflector, or microlens array, among other components. When the computer system 6 sends a switching command to the first reflecting mirror 1c, the first reflecting mirror 1c can adjust its own attitude through automated methods such as electrical control. For example, by adjusting the angle between the first reflecting mirror 1c and the horizontal direction, the reflection direction of the incident light after passing through the first reflecting mirror 1c is changed, thereby altering the focal point of the incident light at the rear focal plane of the first lens 1b. This allows for changing the incident angle for defect detection. It is understood that the first reflecting mirror 1c can be a single optical lens or a group of optical lenses that sequentially reflect light signals. In practical applications, a specific optical system capable of switching attitudes to change the reflection direction of incident light can be configured as needed, and this embodiment is not the only option.

[0064] Furthermore, the half-aperture angle of the first lens 1b determines the adjustment range of the dark field incident angle, and the aperture angle of the first lens 1b... sum of numerical aperture The relationship between them is ,in, This represents the spatial refractive index between the first lens 1b and the sample 3 under test, so the angular range of the dark field incident angle is obtained as follows: ,in, This represents the minimum dark field incident angle required to achieve dark field imaging. In practical applications, specific values ​​are set as needed. , and The values ​​are not limited to those in this embodiment. Furthermore, by continuously recording and adjusting the position of the point light source 1a and the size of the dark field incident angle, a correspondence between the point light source position and the dark field incident angle can be established, which is beneficial for more accurate and convenient adjustment of the dark field incident angle. To ensure the effectiveness of dark field detection, the range of incident angle adjustment should be less than 85 degrees and greater than 5 degrees.

[0065] Figure 3This is an example of azimuth angle transformation in a dark-field imaging defect detection system. Those skilled in the art should understand that the azimuth angle refers to the angle between the perpendicular projection of the incident light propagation vector onto the surface of the sample (i.e., the XY plane) and a preset reference direction of the sample surface. For example, when the direction of the grating lines within the detection area of ​​the sample surface is set as the Y-axis direction, the X-axis direction perpendicular to this grating direction can be defined as the reference direction; under this setting, the azimuth angle is the angle formed by the XY plane projection of the incident light propagation vector and the positive X-axis direction. When the sample 3 is rotated relative to the incident light path 1, multiple azimuth angle transformations can be achieved in the defect detection system. For example... Figure 3 As shown, the computer system 6 instructs the carrier stage 4 to carry the sample 3 to rotate around the normal of the sample surface. At this time, the incident light path 1 is fixed and does not move, thus realizing the azimuth angle change of the current detection area. Figure 4 The following is another example, in which the incident light path 1 is rotated around the normal of the surface of the sample under test by computer command, while the stage 4 and the sample under test 3 do not move. In this case, different azimuth angles can also be changed.

[0066] exist Figure 4 In the example shown, the incident light path 1 can be driven by a motor to rotate the entire incident light path around the sample 3 under test, or more specifically, to rotate around a certain detection area on the sample under test to achieve detection at multiple azimuth angles. Alternatively, the rotation of the incident light path 1 can also be achieved by rotating a single component, such as the first lens 1b, thereby enabling the modulated parallel oblique incident light to rotate around the detection area of ​​the sample under test to complete detection at different azimuth angles.

[0067] exist Figure 5 In the example shown, when different azimuth angles are detected by rotating the stage 3, the rotation of the sample 3 will cause a corresponding rotation in the dark field image observed by the imaging device 5a. Therefore, a compensation lens 5d needs to be added to the imaging optical path of the detection system. The dark field image is compensated by rotating the compensation lens 5d. The compensation lens 5d is placed in the optical path between the sample 3 and the imaging device 5a. As an example, the compensation lens 5d can be a Dove prism. In practical applications, the specific type of compensation lens 5d is set according to needs and is not limited to this embodiment.

[0068] Figure 6 and Figure 9The diagram illustrates a dark-field imaging defect detection system with varying incident and azimuth angles provided by this invention. It should be understood that the surface of the sample 3 under test has a periodic grating structure. When the dark-field imaging defect detection system is performing detection on a certain area of ​​the sample surface, multiple azimuth angles can be adjusted simultaneously during multiple incident angle changes. Alternatively, the defect detection system can be configured to perform only a fixed incident angle and multiple azimuth angle changes, or a combination of multiple incident angles and a fixed azimuth angle, depending on the current detection formula. Furthermore, a fixed incident angle and a fixed azimuth angle can be used for defect detection when the detection area of ​​the sample does not contain a periodic grating structure.

[0069] like Figure 6 As shown, as an example, the incident light path 1 includes a light source 1a, a light source switching device 2, a first lens 1b, a collimating lens 1e, a focusing lens 1f, and a second reflecting mirror 1g; the first lens 1b, the light source switching device 2, the collimating lens 1e, the focusing lens 1f, and the second reflecting mirror 1g belong to the light transmission module. In this example, the light source 1a is set on the light source switching device 2, and the light source position is further switched according to the instructions of the computer system 6 to realize the change of the incident angle. Light with different incident angles is collimated by the collimating lens 1e, reflected by the second reflecting mirror 1g, and transmitted to the focusing lens 1f. The focusing lens 1f focuses the incident light onto the back focal plane of the first lens 1b. After the first lens 1b collimates the incident light, it is obliquely incident on the surface of the sample 3 to achieve the detection of different incident angles. In this example, the imaging light path 5 includes an imaging device 5a, an imaging lens 5b, and an objective lens 5c. The objective lens 5c collects scattered light from the surface of the sample 3 at different incident angles and transmits it to the imaging device 5a through the imaging lens 5b.

[0070] In this example, the azimuth transformation scheme is as follows: Figure 7 As shown, Figure 7 The incident light path is a fully rotating design, with the computer system driving the entire incident light path to rotate via a separately configured rotary motor to achieve azimuth angle changes. Alternatively, the computer system 6 can control only the first lens 1b to rotate to detect different azimuth angles. It should be understood that, as... Figure 7 As shown, in the overall rotation scheme, the incident light path is integrated into the same illumination arm 7, and a rotary motor or similar drive unit drives the overall rotation of the incident light path. In this scheme, the light source, i.e., the corresponding light source switching device, can be set perpendicular to the sample under test to facilitate the implementation of the rotation scheme. It can be understood that when the incident light path rotates electronically, the imaging device 5a acquires dark field images of the detection area on the surface of the sample 3 under test at a preset frequency and different azimuth angles, and finally outputs the defect information of the detection area.

[0071] Figure 8 The example shown is the same as Figure 6 , Figure 7 The difference is that, Figure 8 The incident light path 1 includes a first lens 1b, a first reflector 1c, and a second lens 1d; the first lens 1b, first reflector 1c, and second lens 1d belong to the optical transmission module. The first reflector 1c can be a galvanometer, an acousto-optic deflector, an electro-optic deflector, or a microlens array, etc. As mentioned earlier, when the computer system 6 sends a switching command to the first reflector 1c, the first reflector 1c can adjust its own attitude through automated means such as power control. For example, by adjusting the angle between the first reflector 1c and the horizontal direction, the reflection direction of the incident light is changed, thereby changing the focal position of the incident light on the back focal plane of the first lens. When the first reflector 1c is a single optical lens, the reflection angle is changed by switching the attitude of a single optical lens to adjust the focal position of the incident light on the back focal plane of the first lens. In some examples, the first reflector 1c can also be a group of optical lenses that sequentially reflect light signals. The angle of the reflected light is adjusted by a group of optical lenses, changing the focal position of the incident light on the back focal plane of the first lens, thereby achieving the adjustment of different incident angles.

[0072] As an example, such as Figure 9 The dark-field imaging defect detection system shown includes an incident optical path 1 comprising a light source 1a, a light source switching device 2, a first lens 1b, a collimating lens 1e, and a focusing lens 1f. The first lens 1b, light source switching device 2, collimating lens 1e, and focusing lens 1f belong to the optical transmission module. As mentioned earlier, the light source 1a can be switched horizontally via the light source switching device 2 to detect different incident angles. The light source switching device 2 may include a motor and a light source adapter plate structure. When the motor receives a switching command from the computer system 6, it moves the position of the light source 1a on the horizontal plane of the light source adapter plate. In this example, the light source adapter plate can be a circular device with multiple light source entrance holes. The motor drives rotation to switch between different entrance holes. When the system detects a certain incident angle, the light source does not illuminate through other entrance holes. The light source adapter plate can also be configured as a fiber optic interface. When the light source 1a transmits via fiber optics, different fiber optic interfaces can be switched to achieve different incident angle detections. In practical applications, other switchable entrance hole or interface optical systems can be configured as needed, not limited to this embodiment.

[0073] exist Figure 9 In the dark-field imaging defect detection system shown, azimuth angle transformation is achieved by the self-rotation of the sample 4 carried by the stage 3. When the stage 3 rotates according to a preset rotation angle, in order to ensure the clarity and accuracy of the dark-field image acquired by the imaging device 5a, a compensation lens 5d needs to be added to the imaging device 5 to compensate for the dark-field image. The compensation lens 5d is set in the optical path between the sample 3 and the imaging device 5a.

[0074] like Figure 11 As shown, the angle deviation compensation scheme between the sample coordinate system and the imaging coordinate system of the present invention includes a sample angle direction 901; a Dowell prism 902; and an image angle direction 903. The sample angle direction 901, after being coaxially rotated by the Dowell prism 902, can adjust the image angle direction 903. The angle adjustment relationship 904 is as follows: Figure 11 As shown, the image rotation angle is twice the rotation angle of the Dowell prism 902.

[0075] Therefore, when the support platform 3 rotates according to the preset rotation angle v, the compensation lens 5d should rotate in the same direction at an angle of 0.5v. As an example, the compensation lens 5d can be a Dowell prism 902. In practical applications, the specific type and rotation speed of the compensation lens 5d can be set as needed, and are not limited to this embodiment.

[0076] Figure 10 The dark field imaging defect detection system shown is... Figure 9 The difference is that, Figure 10The incident light path 1 includes a first lens 1b, a first reflector 1c, and a second lens 1d; the first lens 1b, first reflector 1c, and second lens 1d belong to the optical transmission module. As mentioned earlier, the first reflector 1c can be a galvanometer, an acousto-optic deflector, an electro-optic deflector, or a microlens array, etc. When the computer system 6 sends a switching command to the first reflector 1c, the first reflector 1c can adjust its own attitude through automated means such as electrical control. For example, by adjusting the angle between the first reflector 1c and the horizontal direction, the reflection direction of the incident light is changed, thereby changing the focal position of the incident light at the back focal plane of the first lens. In some examples, the first reflector 1c can be a single optical lens or a group of optical lenses that reflect light signals sequentially. It can be a single lens that automatically switches to adjust the reflection angle, or multiple lenses that adjust their attitude together to adjust the focal position of the incident light at the back focal plane of the first lens. In this example, after the incident angle is adjusted by the first reflector 1c, the azimuth angle is changed by rotating the support platform 3. Simultaneously, these two steps can be performed concurrently, or the azimuth angle transformation can be performed first, followed by the incident angle transformation. For example, the system can execute multiple incident angle and azimuth angle transformation detection tasks sequentially according to the formula settings. When the stage 3 rotates at a preset rotation angle, the detection system acquires an image of the detection area of ​​the sample to be tested to identify defect information. Meanwhile, to ensure the clarity and accuracy of the dark-field image acquired by the imaging device 5a, a compensation lens 5d needs to be added to the imaging optical path of the detection system to compensate for the dark-field image. As mentioned earlier, when the stage 3 rotates at a preset rotation angle v, the compensation lens 5d should rotate in the same direction at an angle of 0.5v for imaging compensation. The compensation lens 5d can be a Dove prism or other lenses with similar functions.

[0077] As another embodiment, the present invention also relates to a defect detection method using dark-field imaging. First, an obliquely incident light source is provided. The light signal is collimated by a first lens to generate a collimated light signal, which is then obliquely incident onto the surface of the sample to be tested. Images of the sample surface under multiple incident angles and azimuth angles are scanned and acquired. Based on the acquired multiple images of the sample surface, defect information of at least one periodic angular diffraction characteristic structure on the sample surface is determined. By adjusting the incident angle of the dark-field imaging defect detection system and / or adjusting the azimuth angle of the collimated light signal on the sample, a dark-field image of the sample surface is acquired, thereby obtaining the defect detection result of the sample surface. Therefore, by adjusting the incident angle and azimuth angle of dark-field imaging from multiple angles, the present invention can not only avoid the interference of angular diffraction characteristics of certain structures on the sample surface on dark-field imaging, but also meet the diverse detection needs of the sample. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0078] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A defect detection system for dark-field imaging, characterized in that, The defect detection system for dark-field imaging includes: Light source, platform, optical transmission module, imaging device and computer system; The light source is incident at an angle onto the sample to be tested; The support platform is used to support the sample to be tested; The light transmission module is used to guide the light emitted by the light source to the sample to be tested, and to collect the light scattered from the sample to be tested and transmit it to the imaging device; The imaging device acquires an image of the surface of the sample under test based on the light scattered from the surface of the sample under test. The computer system is used to send angle transformation commands and output defect information of the sample under test based on the image data acquired by the imaging device.

2. The defect detection system for dark-field imaging according to claim 1, characterized in that: The optical transmission module includes a first lens, which is disposed between the light source and the sample to be tested. The light source is modulated into parallel light after passing through the first lens and incident on the surface of the sample to be tested.

3. The defect detection system for dark-field imaging according to claim 2, characterized in that: The focusing position of the light source at the rear focal plane of the first lens is changed to change the incident angle for defect detection.

4. The defect detection system for dark-field imaging according to claim 3, characterized in that: The step of changing the focusing position of the light source at the rear focal plane of the first lens includes: The light source is driven to move in the same plane parallel to the rear focal plane of the first lens.

5. The defect detection system for dark-field imaging according to claim 3, characterized in that: The step of changing the focusing position of the light source at the rear focal plane of the first lens includes: The optical transmission module further includes a first reflector, which is disposed between the light source and the first lens to adjust the reflection angle of the light source after passing through the first reflector.

6. The defect detection system for dark-field imaging according to claim 3, characterized in that: The adjustment range of the incident angle is: ,in, This represents the minimum incident angle of the detection system. This indicates the numerical aperture of the first lens. This represents the spatial refractive index between the first lens and the sample under test.

7. The defect detection system for dark-field imaging according to claim 2, characterized in that: Defect detection is performed by changing the azimuth angle, which is the angle between the vertical projection of the obliquely incident light beam onto the surface of the sample under test and the preset reference direction of the surface of the sample under test.

8. The defect detection system for dark-field imaging according to claim 7, characterized in that: The step of changing the azimuth angle includes: controlling the first lens to rotate around the normal of the sample under test through the computer system.

9. The defect detection system for dark-field imaging according to claim 7, characterized in that: The step of changing the azimuth angle further includes: driving the platform to rotate around the normal of the sample to be tested via the computer system.

10. The defect detection system for dark-field imaging according to claim 9, characterized in that: The step of changing the azimuth angle also includes: A compensation lens is provided in the imaging optical path of the detection system, and the compensation lens is disposed between the sample to be tested and the imaging device. The angular deviation is compensated by rotating the compensation lens.

11. A defect detection method using dark-field imaging, characterized in that, The defect detection method for dark-field imaging includes: Provide an oblique incident light source; The illumination light emitted by the light source is modulated into parallel light and guided to be transmitted to the surface of the sample to be tested; The surface images of the sample under test are scanned and acquired at multiple incident angles and azimuth angles. Based on the acquired multiple surface images of the sample under test, defect information of at least one periodic angular diffraction characteristic structure on the surface of the sample under test is determined.

Images