Defect detection device and defect detection correction method

Abstract

This invention provides a defect detection device and a defect detection correction method. The method includes: an illumination unit providing telecentric illumination as measurement light; the measurement light generating scattered light after passing through a defect on the test object; an image detection unit acquiring the intensity of the scattered light and obtaining defect information based on the intensity; and a control storage unit correlating the intensity of the scattered light with the real-time amplitude of the test object to obtain and store the correspondence between the intensity and amplitude, thereby compensating for the intensity and correcting the defect information. Therefore, this invention correlates the intensity of the scattered light with the real-time amplitude of the test object and obtains their correspondence, thereby compensating for the intensity and correcting the defect information. This avoids the impact of vibration of the test object caused by internal moving mechanisms and external vibrations on the defect detection accuracy, thus improving defect detection accuracy and product yield.

Description

Technical Field

[0001] This invention relates to the field of lithography machines, and in particular to a defect detection device and a method for correcting defects. Background Technology

[0002] In the fabrication processes of integrated circuits or flat panel displays, contamination control is a crucial step in improving product yield. The glass and pellicle surfaces of photomasks, which serve as pattern templates, are susceptible to contamination and damage during clamping, transport, storage, and exposure, resulting in defects such as foreign particles, fingerprints, scratches, and pinholes. If defect detection is not performed before exposure, these defects will directly affect the exposure performance of the lithography machine and the product yield. Therefore, defect detection is necessary before photomask exposure to determine whether the photomask can be used directly for exposure, thereby avoiding the impact of photomask defects on the exposure process.

[0003] Currently, the main method for detecting defects in photomasks utilizes a defect detection device composed of an illumination unit and an image detection unit. Specifically, the illumination unit projects measurement light onto the photomask. This light is scattered at the defects in the photomask, and the scattered light enters the corresponding image detection unit. The image detection unit detects the signal of the scattered light and processes the detection results to obtain information such as the equivalent size of the defects in the photomask. To ensure defect detection accuracy, the illumination unit needs to provide telecentric illumination; the higher the degree of telecentricity, the more accurate the detection.

[0004] However, the detection accuracy of current defect detection devices, which mainly consist of illumination units and image detection units, cannot be further improved. The main reasons include:

[0005] 1. This defect detection device is generally integrated into the lithography machine. Due to the limited mechanical space inside the lithography machine, the existing defect detection device needs to be small enough to avoid occupying too much mechanical space inside the lithography machine, which results in limited defect detection accuracy.

[0006] 2. Since both the upper and lower surfaces of the photomask need to be inspected for defects, the photomask needs to be placed on a plate fork during the actual inspection process. However, because the plate fork is easily affected by the internal motion mechanism of the lithography machine and external vibrations, and the light intensity distribution gradient of the measurement light provided by the illumination unit is large, the repeatability of the defect detection results (e.g., particle grayscale) of the defect detection device is poor, which seriously affects the accuracy of defect detection.

[0007] Therefore, a new defect detection device and a defect detection correction method are needed to improve the accuracy of defect detection. Summary of the Invention

[0008] The purpose of this invention is to provide a defect detection device and a defect detection correction method to solve the problem of low defect detection accuracy.

[0009] To solve the above-mentioned technical problems, the present invention provides a defect detection device, comprising: an illumination unit, an image detection unit, a focal plane measurement unit, and a control storage unit;

[0010] The illumination unit is used to provide measurement light;

[0011] The image detection unit is used to acquire the intensity of the scattered light generated after the measurement light is scattered by the defects on the test object, and to obtain the defect information on the test object based on the light intensity;

[0012] The focal plane measurement unit is used to measure the real-time distance between the object under test and the image detection unit, and to obtain the real-time amplitude of the object under test based on the real-time distance;

[0013] The control storage unit is used to match the light intensity of the scattered light acquired by the image detection unit with the real-time amplitude acquired by the focal plane measurement unit to obtain and store the correspondence between light intensity and amplitude, and to compensate the light intensity of the scattered light detected by the image detection unit according to the correspondence to correct the defect information.

[0014] Optionally, in the defect detection device, the control storage unit further includes an encoder, which is used to mark the amount of time change so as to mark each time period as a corresponding code value interval.

[0015] Optionally, in the defect detection device, the defect detection device further includes a position adjustment unit, which is used to adjust the position of the object to be tested.

[0016] Optionally, in the defect detection device, the position adjustment unit includes a first motion table and a second motion table;

[0017] The first motion stage is used to adjust the distance between the object under test and the image detection unit in a first direction based on the real-time distance obtained by the focal plane measurement unit;

[0018] The second motion stage is used to carry the object to be tested and drive the object to be tested to move along the second direction so as to realize the measurement light scanning the entire surface of the object to be tested.

[0019] Optionally, in the defect detection device, the first direction and the second direction are perpendicular to each other.

[0020] Optionally, in the defect detection device, the illumination unit includes a light emitter and a beam expander; the light emitter is used to provide illumination; the beam expander is used to expand the illumination emitted by the light emitter so that the diameter of the illumination is enlarged and can propagate in parallel.

[0021] Optionally, in the defect detection device, the illumination unit further includes a light adjustment mirror group, which is used to adjust the divergence angle of the expanded light to a preset value.

[0022] Optionally, in the defect detection device, the light adjustment unit mirror assembly includes a cylindrical microlens array and / or a Powell prism.

[0023] Optionally, in the defect detection device, the illumination unit further includes a collimating lens group, which is used to expand the light beam passing through the light adjustment lens group and form parallel measurement light.

[0024] Optionally, in the defect detection device, the image detection unit includes a detection mirror group and a detector; the detection mirror group is used to converge the scattered light and transmit it to the detector; the detector is used to scan and detect the object to be tested.

[0025] Optionally, in the defect detection device, the focal plane measurement unit includes a focusing sensor; the focusing sensor is used to measure the real-time distance between the object under test and the image detection unit, and to obtain the real-time amplitude of the object under test based on the real-time distance.

[0026] Based on the same inventive concept, the present invention also provides a method for correcting defects, comprising:

[0027] The illumination unit provides measurement light;

[0028] The measuring light is scattered after passing through the defect on the object under test, and the image detection unit acquires the intensity of the scattered light and obtains defect information based on the intensity of the light.

[0029] The control storage unit matches the light intensity of the scattered light acquired by the image detection unit with the real-time amplitude of the object under test acquired by the focal plane measurement unit to obtain and store the correspondence between light intensity and amplitude, and compensates the light intensity of the scattered light detected by the image detection unit according to the correspondence to correct the defect information.

[0030] Optionally, in the defect detection correction method, the measurement frequency of the focal plane measurement unit is matched with the acquisition frequency of the image detection unit so that the amplitude of the object under test and the intensity of the corresponding scattered light are matched.

[0031] Optionally, in the defect detection correction method, before the control storage unit matches the light intensity of the scattered light obtained by the image detection unit with the real-time amplitude of the object under test obtained by the focal plane measurement unit, the encoder in the control storage unit is used to mark the time change, so as to mark each time period as the corresponding code value interval.

[0032] Optionally, in the defect detection correction method, the method for compensating the light intensity includes:

[0033] The real-time amplitude within the code value range is averaged to obtain the average amplitude;

[0034] Subtract the average amplitude from the real-time amplitude corresponding to each code value in the code value interval to obtain the amplitude relative value matrix.

[0035] Based on the correspondence between light intensity and amplitude, the relative amplitude matrix is ​​converted into a light intensity fluctuation proportionality coefficient matrix.

[0036] The light intensity matrix formed by the light intensity corresponding to each code value within the code value range is divided by the light intensity fluctuation ratio matrix to compensate for the light intensity and obtain the compensated light intensity.

[0037] Optionally, in the defect detection correction method, after obtaining the compensated intensity of the scattered light, the image detection unit obtains the corrected defect information based on the compensated intensity of the scattered light.

[0038] In summary, this invention provides a defect detection device and a correction method for defect detection. The defect detection device includes an illumination unit, an image detection unit, a focal plane measurement unit, and a control and storage unit. The illumination unit provides measurement light; the measurement light is scattered after passing through a defect on the test object, generating scattered light. The image detection unit acquires the intensity of the scattered light and obtains defect information based on the intensity. However, internal movement and external vibration of the defect detection device can cause vibration of the test object, thus affecting the detection accuracy. Therefore, this invention utilizes the control and storage unit to match the intensity of the scattered light acquired by the image detection unit with the real-time amplitude acquired by the focal plane measurement unit to obtain and store the correspondence between intensity and amplitude. Then, the intensity of the scattered light detected by the image detection unit is compensated according to the correspondence to correct the defect information. Thus, the compensated intensity can reduce the influence of the test object's vibration on the intensity of the scattered light, thereby reducing the error of the defect information obtained by the image detection unit based on the scattered light, achieving correction of the defect information, and improving defect detection accuracy and product yield. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the defect detection device according to an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the structure of the lighting unit according to an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the fork structure according to an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the vibration of the fork in an embodiment of the present invention;

[0043] Figure 5 This is a simulation diagram of the repeatability test of particle grayscale measurement according to an embodiment of the present invention;

[0044] Figure 6 This is a flowchart of the defect detection correction method according to an embodiment of the present invention;

[0045] Figure 7 This is a schematic diagram showing the relationship between the amplitude of the code value interval and the light intensity in an embodiment of the present invention;

[0046] Figure 8 This is a test diagram of the plate fork vibration and light intensity fluctuation according to an embodiment of the present invention;

[0047] Figure 9 This is a schematic diagram of the light intensity fluctuation after compensation according to an embodiment of the present invention;

[0048] Figure 10 This is a simulation diagram of the repeatability test of particle measurement grayscale after compensation according to an embodiment of the present invention. Detailed Implementation

[0049] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clearly illustrate the objectives of the embodiments of the present invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and sometimes use different scales. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are only used to distinguish the various components, elements, steps, etc., in the specification, and are not used to indicate the logical or sequential relationships between the various components, elements, steps, etc.

[0050] To address the aforementioned technical problems, this embodiment provides a defect detection device. Please refer to [link / reference]. Figure 1The defect detection device includes: an illumination unit 10, an image detection unit 20, a focal plane measurement unit 30, a position adjustment unit 40, and a control storage unit 50. The illumination unit 10 is used to measure light. Optionally, the measuring light is telecentric illumination. The image detection unit 20 is used to acquire the intensity of the scattered light generated after the measuring light passes through a defect on the test object M, and to obtain defect information based on the light intensity. The focal plane measurement unit 30 is used to measure the real-time distance between the test object M and the image detection unit 20, and to acquire the real-time amplitude of the test object M based on the real-time distance. The position adjustment unit 40 is used to adjust the position of the test object M. The control storage unit 50 is used to match the intensity of the scattered light acquired by the image detection unit 20 with the real-time amplitude acquired by the focal plane measurement unit 30 to obtain and store the correspondence between light intensity and amplitude, and to compensate the intensity of the scattered light detected by the image detection unit 20 according to the correspondence to correct the defect information.

[0051] Therefore, the defect detection device provided in this embodiment correlates the intensity of the scattered light with the real-time amplitude of the object under test, and obtains the correspondence between the two, thereby compensating for the light intensity based on the correspondence, and thus correcting the defect information. This avoids the impact of the vibration of the object under test caused by the internal moving mechanism and external vibration on the defect detection accuracy, thereby improving the defect detection accuracy and product yield.

[0052] Please continue reading. Figure 1 The control storage unit 50 includes an encoder 501. The encoder 501 is used to mark time changes, marking each time interval as a corresponding code value interval. That is, one time point corresponds to one code value, and each code value interval corresponds to one time interval. According to testing needs, the engineer can select a code value interval and, within the code value interval, match the light intensity of the scattered light acquired by the image detection unit 20 with the real-time amplitude acquired by the focal plane measurement unit 30 to obtain the correspondence between light intensity and amplitude. The light intensity is then compensated according to this correspondence to correct the defect information. Furthermore, the encoder 501 can be mounted on the second motion stage 402.

[0053] The position adjustment unit 40 includes a first motion stage 401 and a second motion stage 402. The first motion stage 401 is used to adjust the distance between the object under test M and the image detection unit 20 in a first direction (Z direction in this embodiment) based on the real-time distance obtained by the focal plane measurement unit 30. Typical measurement principles include, but are not limited to, multi-wavelength confocal measurement and triangulation. That is, the vertical height (height in the Z direction) of the object under test M is adjusted according to the real-time distance obtained by the focal plane measurement unit 30 to ensure that the scattered light can enter the image detection unit 20, and when the measurement light is projected onto the surface of the object under test M and there are no defects, the measurement light is reflected by the object under test M and generates reflected light, which does not enter the image detection unit 20.

[0054] The second motion stage 402 is used to carry the object to be tested M and drive the object to be tested M to move along the second direction (in this embodiment, the horizontal direction Y) so as to realize the measurement light scanning the entire surface of the object to be tested M. The first direction Z and the second direction Y are perpendicular to each other.

[0055] Furthermore, in this embodiment, the test object M is taken as an example. Please refer to [link / reference]. Figure 2 The length and width of a commonly used mask are about 152mm, and the effective area is usually 132mm*104mm or more. This requires that the line light spot generated by the illumination unit 10 needs to be at least 104mm, preferably greater than 125mm.

[0056] To ensure the accuracy of defect detection, the measurement light generated by the illumination unit 10 has the following characteristics: the deviation between the principal rays of each field of view in the measurement beam is less than 5 degrees, preferably less than 1 degree. That is, the measurement light provided by the illumination unit 10 needs to be telecentric illumination. The illumination field of view d of the telecentric illumination, the focal length f of the collimating lens group, and the divergence angle θ of the measurement light satisfy the following relationship:

[0057] d = f*sin(θ)*2;

[0058] However, due to the very limited mechanical space inside the lithography machine, the defect detection device must be compact, meaning the focal length f of the collimating lens group 104 must be minimized. Therefore, while ensuring telecentric illumination, the divergence angle θ of the measurement light needs to be increased to meet these requirements.

[0059] To address this, this embodiment provides a lighting unit 10. Please continue reading. Figure 2The illumination unit 10 includes a light emitter 101, a beam expander 102, a light adjustment lens group 103, and a collimating lens group 104 arranged sequentially along the optical path. The light emitter 101, for example, is a laser emitter, used to provide linear illumination, which propagates to the beam expander 102. The beam expander 102 expands the illumination beam, increasing its diameter and allowing it to propagate parallel to the light adjustment lens group 103. The light adjustment lens group 103 includes a cylindrical microlens array and / or a Powell prism, used to adjust the divergence angle of the illumination to a preset value and propagate it to the collimating lens group 104. The collimating lens group 104 expands the illumination beam and forms a parallel measurement beam. The divergence angle of the illumination after passing through the cylindrical microlens array and / or Powell prism can be adjusted to above 20 degrees, thereby allowing the focal length of the collimating lens group 104 to be controlled below 150mm, or even below 125mm. Therefore, the lighting unit 10 provided in this embodiment can meet the requirement of reducing the space occupied by the defect detection device, and has better adaptability and expandability.

[0060] Furthermore, the preset value range of the divergence angle is: greater than 20 degrees and less than 90 degrees, preferably 25 degrees, 30 degrees or 35 degrees, etc.

[0061] Please continue reading. Figure 1 The image detection unit 20 includes a detection lens group 201 and a detector 202. When a defect exists on the surface of the object under test M, the measurement light is scattered by the defect, generating scattered light. The detection lens group 201 is used to converge the scattered light and transmit it to the detector 202. When the surface of the object under test M is free of defects, the image detection unit 20 does not receive the light beam, and the measurement light is reflected by the surface of the object under test M and exits the image detection unit 20. The detector 202 is a detection camera used to continuously capture images of the scattered light and obtain the light intensity of the scattered light based on the images, thereby obtaining the defect information of the object under test. The defect information includes the equivalent size information and position coordinate information of the defect.

[0062] Furthermore, the focal plane measurement unit 30 includes a focusing sensor. The focusing sensor is used to measure the real-time distance between the object under test M and the image detection unit 20, and can calculate the real-time amplitude of the object under test M, i.e., the vibration of the object under test M over time, based on the real-time distance.

[0063] However, in actual testing, both the upper and lower surfaces of the object under test M (in this embodiment, the mask) need to be inspected for defects, therefore... Figure 3The fork N shown is used to support the mask. The shape of the fork N is generally U-shaped to facilitate matching with the shape of the mask. To support the mask and meet the detection requirements, the thickness of the fork N is limited and cannot be made thick. This results in the fork N having a low modal response, making it susceptible to the influence of internal moving mechanisms and external vibrations, which in turn causes the mask to vibrate, affecting the accuracy of the detection.

[0064] Please see Figure 4 , Figure 4 This is a test image showing the vibration of the mask fork N during defect detection, caused by the influence of internal motion mechanisms and externally introduced vibrations. It is evident that the vibration of the mask fork N directly affects the detection accuracy. Although the image detection unit 20 in the defect detection device uses detector integration to homogenize the scattered light, it still cannot reduce the impact of vibration on detection accuracy. Furthermore, due to the vibration of the mask fork N, the incident angle of the measurement light and the receiving angle of the image detection unit 20 deviate from the normal direction of the mask, thus amplifying the impact of vibration on detection accuracy.

[0065] Since the repeatability of particle grayscale measurement is a core indicator for defect detection, and when the particle size is less than 30 micrometers, the repeatability of particle grayscale measurement must be less than ±3 micrometers, then by... Figure 4 Simulations based on measured vibration data revealed that this vibration significantly reduced the repeatability of particle grayscale measurements by up to 16.7%. Please refer to [link / reference]. Figure 5 At a particle size of 25 micrometers, due to significant vibration, the repeatability of particle grayscale measurements, after multiple measurements, reached a maximum of ±8 micrometers, which is insufficient for accurate detection. This demonstrates that vibration can cause substantial interference in defect detection.

[0066] Analysis shows that when vibration occurs, the dwell time of the measuring light at the corresponding field of view changes, causing large fluctuations in the acquired light intensity values, resulting in poor repeatability. In other words, due to vertical vibration, the velocity of the plate fork N in the horizontal direction (Y direction) changes instantaneously. Furthermore, the large gradient of the measuring light intensity distribution results in some areas of high intensity and others of low intensity. If the horizontal velocity is unstable, it is difficult to accurately acquire the light intensity values ​​in each field of view. For example, in the first case: at the field of view with the highest relative light intensity, the instantaneous horizontal velocity of the plate fork N is the slowest, resulting in an excessively high light intensity at that position. Conversely, at the field of view with the lowest relative light intensity, the instantaneous horizontal velocity of the plate fork N is the fastest, potentially failing to capture low-intensity values. Therefore, in the first case, the acquired light intensity at that field of view is ultimately too high. In the second case: at the field of view with the highest relative light intensity, the instantaneous horizontal velocity of the plate fork N is the fastest, potentially failing to capture high-intensity values. At the position of lowest relative light intensity in the field of view, the horizontal instantaneous velocity of the fork N is the slowest, resulting in an underestimation of the light intensity at that position. Therefore, in the second scenario, the final light intensity at that position is also lower than expected.

[0067] Therefore, the vertical vibration of the plate fork N causes an instantaneous change in the velocity of the plate fork N in the horizontal direction Y, resulting in fluctuations in the scattered light, affecting the repeatability of particle grayscale measurement, and thus affecting the accuracy of obtaining light intensity information, thereby reducing the defect detection accuracy.

[0068] Therefore, the defect detection device provided in this embodiment can correct for errors caused by vibration. The control storage unit 50 in the defect detection device provided in this example can match the light intensity of the scattered light acquired by the image detection unit 20 with the real-time amplitude of the object M under test acquired by the focal plane measurement unit 30 within a set code value range to obtain the correspondence between light intensity and amplitude. Based on this correspondence, the light intensity is compensated, thereby correcting the defect information and reducing the impact of vibration on detection accuracy. For details, please refer to the following defect detection correction method.

[0069] Based on the same inventive concept, this embodiment also provides a defect detection and correction method. Please refer to [link to relevant documentation]. Figure 1 and 6 ,include:

[0070] Step 1 S10: The illumination unit 10 provides measurement light. Through the cylindrical microlens array and / or Powell prism in the light adjustment lens group 103, and in conjunction with the collimating lens group 104, the illumination unit 10 can not only provide telecentric illumination, but also meet the requirement of reducing the space occupied by the defect detection device, so as to improve its adaptability and expandability.

[0071] Step 2 S20: The measuring light is scattered after passing through the defect on the object under test M and generates scattered light. The image detection unit 20 acquires the intensity of the scattered light and obtains defect information based on the intensity.

[0072] Step 3 S30: The encoder 501 in the control storage unit 50 marks the time change, so that each time period is marked as a corresponding code value interval. Then, the control storage unit 50 matches the light intensity of the scattered light obtained by the image detection unit 20 with the real-time amplitude of the test object M obtained by the focal plane measurement unit 30 within the selected code value interval to obtain the correspondence between light intensity and amplitude. The light intensity is compensated according to the correspondence, thereby correcting the defect information.

[0073] First, the code value of the encoder 501 is linearly fitted to match the number of image acquisition frames of the image detection unit 20 and the acquisition frequency of the focal plane measurement unit 30. Then, the fitted code value of the encoder 501 replaces the original code value, and a set code value range is extracted.

[0074] Secondly, the measurement frequency of the focal plane measurement unit 30 is matched with the acquisition frequency of the image detection unit 20 so that, under the same code value, the amplitude of the object under test M and the intensity of the scattered light are matched. For details, please refer to... Figure 7 In this embodiment, the code value region [5185330, 8451997] is selected as an example. Within the code value region [5185330, 8451997], the corresponding images 203 acquired by the image detection unit 20 are frames 1 to 3500. After matching, the light intensity of the first frame corresponds to the code value 5185330, the light intensity of the 3500th frame corresponds to the code value 8451997, and other code values ​​within the corresponding interval also correspond to the corresponding images. Similarly, the focus sensor also has corresponding readings within the code value region [5185330, 8451997]. The reading of the focus sensor at code value 5185330 corresponds to the light intensity of the first frame, and the reading at code value 8451997 corresponds to the light intensity of the 3500th frame. Furthermore, other code values ​​within the interval are matched one-to-one with the corresponding images and the corresponding focus sensor readings.

[0075] The encoder 501 operates in hard-triggered mode. While reading the focus sensor, the encoder 501 value is simultaneously read, and the focus sensor reading is correlated with the image acquisition frame using the encoder 501 value. Then, as... Figure 8 As shown, the intensity of the scattered light and the real-time amplitude of the object under test M are normalized to obtain the correspondence between the intensity and the amplitude.

[0076] After obtaining the correspondence between light intensity and amplitude, the real-time amplitude within the code value interval is averaged to obtain an average amplitude. Then, the average amplitude is subtracted from the real-time amplitude corresponding to each code value within the code value interval to obtain an amplitude relative value matrix. Finally, based on the correspondence between light intensity and amplitude, the amplitude relative value matrix is ​​converted into a light intensity fluctuation ratio coefficient matrix. The light intensity matrix formed by the light intensity corresponding to each code value within the code value interval is then divided by the light intensity fluctuation ratio coefficient matrix to compensate for the light intensity, obtaining a compensated light intensity. After obtaining the compensated light intensity, the image detection unit 20 obtains the corrected defect information based on the compensated light intensity.

[0077] in, Figure 9 This is a schematic diagram of the compensated light intensity fluctuation. Figure 10 The image shows a simulation of the repeatability of the measured grayscale of the particles after compensation. It can be seen that the repeatability of the measured grayscale of the particles after compensation is reduced from ±8 micrometers to ±2.1 micrometers, meeting the detection requirements and greatly improving the accuracy of defect detection.

[0078] In summary, the defect detection device and correction method provided in this embodiment utilize the control storage unit 50 to match the intensity of the scattered light acquired by the image detection unit 20 with the real-time amplitude acquired by the focal plane measurement unit 30, thereby obtaining and storing the correspondence between intensity and amplitude. Then, the intensity of the scattered light detected by the image detection unit 20 is compensated according to this correspondence to correct the defect information. Thus, the compensated intensity reduces the influence of the test object's vibration on the intensity of the scattered light, thereby reducing the error of the defect information acquired by the image detection unit 20 based on the scattered light, achieving correction of the defect information, and improving defect detection accuracy and product yield. Furthermore, through the cylindrical microlens array and / or Powell prism in the light adjustment lens group 103, and in conjunction with the collimating lens group 104, the illumination unit 10 not only provides telecentric illumination but also meets the requirement of reducing the space occupied by the defect detection device, thus improving its adaptability and expandability.

[0079] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A defect detection device, characterized in that, The defect detection device includes: an illumination unit, an image detection unit, a focal plane measurement unit, and a control and storage unit; The illumination unit is used to provide measurement light; The image detection unit is used to acquire the intensity of the scattered light generated after the measurement light is scattered by the defects on the test object, and to obtain the defect information on the test object based on the light intensity; The focal plane measurement unit is used to measure the real-time distance between the object under test and the image detection unit, and to obtain the real-time amplitude of the object under test based on the real-time distance; The control storage unit is used to match the measurement frequency of the focal plane measurement unit with the acquisition frequency of the image detection unit, so that the light intensity of the scattered light acquired by the image detection unit matches the real-time amplitude acquired by the focal plane measurement unit, so as to obtain and store the correspondence between light intensity and amplitude, and to compensate the light intensity of the scattered light detected by the image detection unit according to the correspondence, so as to correct the defect information.

2. The defect detection device according to claim 1, characterized in that, The control storage unit includes an encoder, which is used to mark the amount of time change so as to mark each time period as a corresponding code value range.

3. The defect detection device according to claim 1, characterized in that, The defect detection device further includes a position adjustment unit, which is used to adjust the position of the object to be tested.

4. The defect detection device according to claim 3, characterized in that, The position adjustment unit includes a first motion table and a second motion table; The first motion stage is used to adjust the distance between the object under test and the image detection unit in a first direction based on the real-time distance obtained by the focal plane measurement unit; The second motion stage is used to carry the object to be tested and drive the object to be tested to move along the second direction so as to realize the measurement light scanning the entire surface of the object to be tested.

5. The defect detection device according to claim 4, characterized in that, The first direction and the second direction are perpendicular to each other.

6. The defect detection device according to claim 1, characterized in that, The illumination unit includes a light emitter and a beam expander; the light emitter is used to provide illumination; the beam expander is used to expand the illumination emitted by the light emitter so that the diameter of the illumination is enlarged and can propagate in parallel.

7. The defect detection device according to claim 6, characterized in that, The illumination unit also includes a light adjustment lens group, which is used to adjust the divergence angle of the expanded light to a preset value.

8. The defect detection device according to claim 7, characterized in that, The light adjustment lens group includes a cylindrical microlens array and / or a Powell prism.

9. The defect detection device according to claim 7, characterized in that, The illumination unit further includes a collimating lens group, which is used to expand the light beam passing through the light adjustment lens group and form parallel measurement light.

10. The defect detection device according to claim 1, characterized in that, The image detection unit includes a detection mirror group and a detector; the detection mirror group is used to converge the scattered light and transmit it to the detector; the detector is used to scan and detect the object to be tested.

11. The defect detection device according to claim 1, characterized in that, The focal plane measurement unit includes a focusing sensor; the focusing sensor is used to measure the real-time distance between the object under test and the image detection unit, and to obtain the real-time amplitude of the object under test based on the real-time distance.

12. A method for correcting defects, characterized in that, Using the defect detection apparatus as described in any one of claims 1 to 11, the defect detection and correction method includes: The illumination unit provides measurement light; The measuring light is scattered after passing through the defect on the object under test, and the image detection unit acquires the intensity of the scattered light and obtains defect information based on the intensity of the light. The control storage unit matches the measurement frequency of the focal plane measurement unit with the acquisition frequency of the image detection unit, so that the light intensity of the scattered light acquired by the image detection unit matches the real-time amplitude of the object under test acquired by the focal plane measurement unit, thereby acquiring and storing the correspondence between light intensity and amplitude, and compensating the light intensity of the scattered light detected by the image detection unit according to the correspondence, so as to correct the defect information.

13. The defect detection correction method according to claim 12, characterized in that, Before the control storage unit matches the intensity of the scattered light obtained by the image detection unit with the real-time amplitude of the object under test obtained by the focal plane measurement unit, the encoder in the control storage unit marks the time change, so as to mark each time period as the corresponding code value interval.

14. The defect detection correction method according to claim 13, characterized in that, The method for compensating for the light intensity in the defect detection correction method includes: The real-time amplitude within the code value range is averaged to obtain the average amplitude; Subtract the average amplitude from the real-time amplitude corresponding to each code value in the code value interval to obtain the amplitude relative value matrix; Based on the correspondence between light intensity and amplitude, the relative amplitude matrix is ​​converted into a light intensity fluctuation proportionality coefficient matrix. The light intensity matrix formed by the light intensity corresponding to each code value within the code value range is divided by the light intensity fluctuation ratio matrix to compensate for the light intensity and obtain the compensated light intensity.

Images