Dark-field confocal microscopy measurement device and method based on multi-fractional angular momentum demodulation

Abstract

The present application discloses a dark field confocal microscopy measurement device and method based on multi-fractional angular momentum demodulation, which relates to the field of confocal microscopy measurement technology. The device comprises: a modulated illumination module and a signal acquisition and demodulation module; in the modulated illumination module, vortex light of different fractional orders is modulated by vortex phase diagrams of different fractional orders to scan the sample to be measured, and the vortex light of different fractional orders is irradiated on the sample to be measured and then reflected; the reflected light is collected by the signal acquisition and demodulation module and a dark field image is generated; finally, cross-correlation processing is performed on the dark field images generated under the vortex light of different fractional orders to obtain high signal-to-noise ratio data; the above-mentioned device provided by the present application uses vortex light of different fractional orders to illuminate the sample and perform dark field detection, which can simultaneously obtain the response of defects to multi-order vortex components, thereby improving the signal strength of tiny defects, and using the cross-correlation algorithm to effectively suppress common mode noise and highlight the weak related information of nano-scale defects.

Description

Technical Field

[0001] The present application relates to the technical field of confocal microscopy measurement, and in particular to a dark-field confocal microscopy measurement device and method based on multi-fractional angular momentum demodulation. Background Art

[0002] Interlayer defects in 3D integrated circuits (such as voids and stacking faults) can easily degrade the electrical performance and lifespan of integrated circuits. Detecting interlayer defects ensures the yield of semiconductor 3D integrated circuits. Confocal microscopy, due to its 3D tomography capabilities, can be used for non-destructive defect detection in 3D integrated circuits.

[0003] Dark-field confocal microscopy has the advantages of good optical tomography capabilities, high imaging resolution, and high imaging contrast brought by dark background, and has become an important means of non-destructive three-dimensional detection of semiconductors. However, ordinary optical dark-field confocal microscopy has a low response rate to tiny-scale defects, and the detection rate for nanoscale defects below 50nm is insufficient. In dark-field confocal, factors such as light source quality, environmental noise, and detector noise seriously affect the measurement accuracy and detection sensitivity of the confocal system. Therefore, how to improve the response rate, reduce imaging noise, and stably improve the sensitivity of dark-field confocal to more comprehensively characterize the interlayer defect characteristics of three-dimensional integrated circuits is a problem that technicians in this field urgently need to solve. Summary of the Invention

[0004] The purpose of this application is to provide a dark field confocal microscopy measurement device and method based on multi-fractional angular momentum demodulation, which can improve the response rate, reduce imaging noise, and stably improve the sensitivity of dark field confocal.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a dark-field confocal microscopy measurement device based on multi-fractional angular momentum demodulation, comprising: a modulated illumination module, a sample to be measured, a three-dimensional electric translation stage, and a signal acquisition and demodulation module.

[0007] The modulated illumination module is used to modulate vortex light of different fractional orders through vortex phase images of different fractional orders to scan the sample to be tested. The vortex light of different fractional orders is irradiated on the sample to be tested and then reflected. The sample to be tested is fixed on a three-dimensional electric translation stage, which is used to drive the sample to be tested to move within the field of view of the modulated illumination module.

[0008] The signal acquisition and demodulation module is used to: collect the reflected light after vortex light of different fractional orders is irradiated on the sample to be tested, and generate a dark field image; for any fractional order of vortex light, the signal acquisition and demodulation module generates a dark field image; based on the dark field images generated under the vortex light of different fractional orders, cross-correlation processing is performed to obtain high signal-to-noise ratio data.

[0009] In a second aspect, the present application provides a dark field confocal microscopy measurement method based on multi-fractional angular momentum demodulation, comprising the following steps:

[0010] The laser is modulated by the first fractional-order vortex phase image to obtain the corresponding fractional-order vortex light.

[0011] The sample to be tested is driven to move within the field of view of the vortex light to complete the scanning of the sample to be tested.

[0012] The reflected light from the sample to be tested is collected and a dark field image is generated. A dark field image can be generated for any fractional order of vortex light.

[0013] It is determined whether all fractional-order vortex phase images have completed the modulation of the laser, and a first determination result is obtained.

[0014] If the first judgment result is no, the laser is modulated using the next fractional-order vortex phase image to obtain the corresponding fractional-order vortex light, and the process jumps to the step of moving the sample to be tested within the field of view of the vortex light to complete the scanning of the sample to be tested; until all fractional-order vortex phase images have completed the modulation of the laser and obtained several dark-field images.

[0015] If the first judgment result is yes, cross-correlation processing is performed based on a plurality of dark field images to obtain high signal-to-noise ratio data.

[0016] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0017] The present application provides a dark field confocal microscopy measurement device and method based on multi-fractional angular momentum demodulation, the device includes: a modulated illumination module, a sample to be measured, a three-dimensional electric translation stage and a signal acquisition and demodulation module; in the modulated illumination module, vortex light of different fractional orders is modulated by vortex phase diagrams of different fractional orders to scan the sample to be measured, and the vortex light of different fractional orders is reflected after being irradiated on the sample to be measured; the reflected light of the vortex light of different fractional orders after being irradiated on the sample to be measured is collected by the signal acquisition and demodulation module, and a dark field image is generated; for any fractional order of vortex light, a dark field image can be generated. image; finally, cross-correlation processing is performed on the dark field images generated under vortex light of different fractional orders to obtain high signal-to-noise ratio data; the above-mentioned device provided in the present application uses fractional-order vortex light to illuminate the sample and perform dark field detection. At the same time, since it contains multiple fractional-order vortex components, the response of the defect to the multi-order vortex components can be obtained at the same time, thereby improving the signal strength of tiny defects. Then, the cross-correlation algorithm can be used to effectively suppress common-mode noise, highlight the weak related information of nano-scale defects, improve the response rate, and reduce imaging noise, thereby achieving an improvement in defect detection sensitivity, thereby more comprehensively characterizing the defect characteristics between layers of three-dimensional integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 Schematic diagram of the structure of a dark-field confocal microscopy measurement device based on multi-fractional angular momentum demodulation in one embodiment of the present application.

[0020] Figure 2 A flowchart of a dark-field confocal microscopy measurement method based on multi-fractional angular momentum demodulation is provided in one embodiment of the present application.

[0021] Figure 3 This is a flow chart of step S1 in a dark-field confocal microscopy measurement method based on multi-fractional angular momentum demodulation provided in one embodiment of the present application.

[0022] Figure 4 Schematic diagram of step S6 in a dark field confocal microscopy measurement method based on multi-fractional angular momentum demodulation provided in one embodiment of the present application

[0023] Description of reference numerals:

[0024] 1—Laser; 2—Two-dimensional optical diffraction element; 3—Turntable; 4—Beam expander; 5—Non-polarizing beam splitter; 6—Objective lens; 7—Sample to be measured; 8—Three-dimensional motorized translation stage; 9—Aperture diaphragm; 10—Focusing lens; 11—Pinhole; 12—Photodetector; 13—Industrial computer. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0027] In an exemplary embodiment, Figure 1 As shown, a dark-field confocal microscopy measurement device based on multi-fractional angular momentum demodulation is provided. The device comprises a modulated illumination module, a sample 7 to be measured, a three-dimensional motorized translation stage 8, and a signal acquisition and demodulation module. The sample 7 to be measured is placed on the three-dimensional motorized translation stage 8. The modulated illumination module emits vortex light onto the sample 7, and the reflected light is collected and processed by the signal acquisition and demodulation module.

[0028] The modulated illumination module is used to modulate vortex light of different fractional orders through vortex phase images of different fractional orders to scan the sample to be tested 7. The vortex light of different fractional orders is irradiated on the sample to be tested 7 and then reflected out; the sample to be tested 7 is fixed on a three-dimensional electric translation stage 8, which is used to drive the sample to be tested 7 to move within the field of view of the modulated illumination module.

[0029] The signal acquisition and demodulation module is used to: collect the reflected light after the vortex light of different fractional orders is irradiated on the sample to be tested 7, and generate a dark field image; for any fractional order of vortex light, the signal acquisition and demodulation module generates a dark field image; based on the dark field images generated under the vortex light of different fractional orders, cross-correlation processing is performed to obtain high signal-to-noise ratio data.

[0030] In a specific embodiment, the modulated lighting module includes: a laser 1, a two-dimensional optical diffraction element 2, a turntable 3, and a beam expander 4; the laser light emitted by the laser 1 enters the signal acquisition and processing module via the two-dimensional optical diffraction element 2, the turntable 3, and the beam expander 4. Specifically, a plurality of vortex phase patterns of different fractional orders are etched on the two-dimensional optical diffraction element 2 in a circular arrangement; the laser 1 is used to emit laser light; the two-dimensional optical diffraction element 2 is used to modulate the laser light into vortex light of the corresponding fractional order using a vortex phase pattern of any fractional order; the turntable 3 is used to rotate the two-dimensional optical diffraction element 2 so that the two-dimensional optical diffraction element 2 can modulate the laser light using vortex phase patterns of different fractional orders; and the beam expander 4 is used to expand the vortex light and output it.

[0031] In a preferred embodiment, the phase difference between the vortex phase patterns etched on the two-dimensional optical diffraction element 2 satisfies an arithmetic progression. Among the multiple vortex phase patterns etched on the two-dimensional optical diffraction element 2, the minimum phase is greater than 0.5 and the maximum phase is less than 1.5.

[0032] In this embodiment, among the multiple vortex phase images etched on the two-dimensional optical diffraction element 2, the fractional order difference between two adjacent vortex phase images is 0.05-0.1.

[0033] In a specific embodiment, the signal acquisition and demodulation module includes: a non-polarizing beam splitter 5, an objective lens 6, an aperture 9, a focusing lens 10, a pinhole 11, a photodetector 12 and an industrial computer 13; the illumination light is emitted from the modulated illumination module, passes through the non-polarizing beam splitter 5 and the objective lens 6 to illuminate the sample 7, and its return light passes through the aperture 9 and is focused by the focusing lens 10 through the pinhole 11 to the photodetector 12. The photodetector 12 converts the optical signal into an electrical signal to generate a pixel image and transmits it to the industrial computer 13. Specifically, the non-polarizing beam splitter 5 is used to transmit the vortex light of different fractional orders output by the modulated illumination module through the objective lens 6 to the sample to be tested 7, and receive the reflected light reflected from the sample to be tested 7 and then passed through the objective lens 6, and transmit the reflected light to the photodetector 12 through the aperture 9, the focusing lens 10, and the pinhole 11; the photodetector 12 is used to convert the reflected light into an electrical signal, generate a dark field image, and send the dark field image to the industrial computer 13; the industrial computer 13 is used to perform n-order cross-correlation processing on the signal intensity under the illumination of vortex light of different fractional orders at the same position according to the dark field image generated under vortex light of different fractional orders, and accumulate and sum the results of the n-order cross-correlation processing, calculate the similar parts, and obtain high signal-to-noise ratio data.

[0034] In a preferred embodiment, the size of the aperture 9 matches the central dark spot diameter of the light beam output after beam expansion by the beam expander 4, and only the central scattered signal is retained.

[0035] The device provided in the above embodiment uses vortex light of different fractional orders to illuminate the sample and perform dark field detection. At the same time, since it contains multiple fractional-order vortex components, the response of defects to multi-order vortex components can be obtained simultaneously, thereby improving the signal strength of tiny defects. Then, the cross-correlation algorithm can be used to effectively suppress common-mode noise, highlight the weak related information of nano-scale defects, improve the response rate, and reduce imaging noise, thereby achieving an improvement in defect detection sensitivity, thereby more comprehensively characterizing the interlayer defect characteristics of three-dimensional integrated circuits.

[0036] Based on the same inventive concept, embodiments of the present application also provide a dark-field confocal microscopy method applicable to the aforementioned dark-field confocal microscopy device based on multi-fractional angular momentum demodulation. The solution provided by this method is similar to the solution described in the aforementioned device. Therefore, the specific limitations of one or more of the following method embodiments can be found in the above-mentioned limitations of the dark-field confocal microscopy device based on multi-fractional angular momentum demodulation, and will not be further elaborated here.

[0037] In an exemplary embodiment, Figure 2 As shown, a dark field confocal microscopy measurement method based on multi-fractional angular momentum demodulation is provided. The method is executed by a computer device and includes the following steps S1 to S6:

[0038] S1, modulate the laser through the first fractional order vortex phase image to obtain the corresponding fractional order vortex light. Figure 3 In the flowchart shown, step S1 specifically includes the following steps:

[0039] S11, controlling the laser to emit laser light.

[0040] S12. Using the first fractional-order vortex phase diagram of the two-dimensional optical diffraction element, the laser is modulated into a vortex light of the corresponding fractional order; a plurality of vortex phase diagrams of different fractional orders are etched on the two-dimensional optical diffraction element in a circular arrangement.

[0041] S2. The sample to be tested is driven to move within the field of view of the vortex light to complete the scanning of the sample to be tested.

[0042] S3. Collect the reflected light reflected from the sample to be tested and generate a dark field image; a dark field image can be generated for any fractional order of vortex light.

[0043] S4: Determine whether all fractional-order vortex phase images have completed the modulation of the laser, and obtain a first determination result. If the first determination result is no, execute step S5; if the first determination result is yes, execute step S6.

[0044] S5: Modulate the laser light using the next fractional-order vortex phase image to obtain vortex light of the corresponding fractional order, and then jump to step S2; until all fractional-order vortex phase images have completed the laser light modulation, a plurality of dark field images are obtained. Specifically in this embodiment, step S5 is specifically: rotating the two-dimensional optical diffraction element by a turntable, and modulating the laser light using the next fractional-order vortex phase image of the two-dimensional optical diffraction element.

[0045] S6. Perform cross-correlation processing on several dark field images to obtain high signal-to-noise ratio data. Figure 4 In the flowchart shown, step S6 specifically includes the following steps:

[0046] S61 , performing n-order cross-correlation processing on the signal intensities of the same position under illumination of the vortex light of different fractional orders according to the dark field images generated under the vortex light of different fractional orders.

[0047] S62. Accumulate and sum the results of the n-order cross-correlation processing, calculate the similar parts, and obtain high signal-to-noise ratio data. Assuming that the sample is stationary under different angles of illumination, the specific response of the sample under different angles of illumination can be expressed as shown in formula (1):

[0048] δF(r,l)=F(r,l)-<F(r,l)> l (1)

[0049] Where δF is the difference between the signal intensity at a certain order and the mean signal intensity at multiple orders, r is the spatial coordinate, l is the vortex light order, and the calculation formula for the n-order cross-correlation can be expressed as follows:

[0050] G n (r,l1,...,l n-1 )=<δF(r,l1)δF(r,l2)...δF(r,l n-1 )> l (2)

[0051] Among them, G n () means the n-order cross-correlation value, n is the cross-correlation order, l n-1 The meaning is the order of the n-1th vortex light, <,,,> l The meaning is the average signal intensity under vortex light illumination of different orders.

[0052] The above method provided in this embodiment uses fractional-order vortex light to illuminate the sample and perform dark field detection. At the same time, since it contains multiple fractional-order vortex components, the response of the defect to the multiple-order vortex components can be obtained simultaneously, thereby improving the signal strength of tiny defects. Then, the cross-correlation algorithm is used to effectively suppress common-mode noise, highlight the weak related information of nano-scale defects, improve the response rate, and reduce imaging noise, thereby achieving an improvement in defect detection sensitivity, thereby more comprehensively characterizing the interlayer defect characteristics of three-dimensional integrated circuits.

[0053] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A dark field confocal microscopy measurement device based on multi-fractional angular momentum demodulation, characterized in that: include: Modulation lighting module, sample to be tested, three-dimensional electric translation stage and signal acquisition and demodulation module; The modulated illumination module is used to modulate vortex light of different fractional orders through vortex phase images of different fractional orders to scan the sample to be tested, and the vortex light of different fractional orders is irradiated on the sample to be tested and then reflected; the sample to be tested is fixed on the three-dimensional electric translation stage, and the three-dimensional electric translation stage is used to drive the sample to be tested to move within the field of view of the modulated illumination module; The modulated lighting module includes: a laser, a two-dimensional optical diffraction element, a turntable and a beam expander; the two-dimensional optical diffraction element is etched with a plurality of vortex phase patterns of different fractional orders in a circular arrangement; the laser is used to emit laser light; the two-dimensional optical diffraction element is used to modulate the laser light into vortex light of corresponding fractional order using a vortex phase pattern of any fractional order; the turntable is used to rotate the two-dimensional optical diffraction element so that the two-dimensional optical diffraction element can modulate the laser light using vortex phase patterns of different fractional orders; the beam expander is used to expand the vortex light and output it; The signal acquisition and demodulation module is used to: collect reflected light reflected after vortex light of different fractional orders is irradiated on the sample to be tested, and generate a dark field image; for the vortex light of any fractional order, the signal acquisition and demodulation module generates a dark field image; and perform cross-correlation processing on the dark field images generated under vortex light of different fractional orders to obtain high signal-to-noise ratio data.

2. The dark field confocal microscopy measurement device based on multi-fractional angular momentum demodulation according to claim 1, characterized in that: The phase differences between the vortex phase patterns etched on the two-dimensional optical diffraction element satisfy an arithmetic progression.

3. The dark field confocal microscopy measurement device based on multi-fractional angular momentum demodulation according to claim 2, characterized in that: In the plurality of vortex phase images etched on the two-dimensional optical diffraction element, the minimum phase is greater than 0.5 and the maximum phase is less than 1.

5.

4. The dark field confocal microscopy measurement device based on multi-fractional angular momentum demodulation according to claim 2, characterized in that: In the plurality of vortex phase images etched on the two-dimensional optical diffraction element, the fractional order of two adjacent vortex phase images differs by 0.05-0.

1.

5. The dark field confocal microscopy measurement device based on multi-fractional angular momentum demodulation according to claim 1, characterized in that: The signal acquisition and demodulation module includes: a non-polarizing beam splitter, an objective lens, an aperture, a focusing lens, a pinhole, a photodetector and an industrial computer; the non-polarizing beam splitter is used to transmit the vortex light of different fractional orders output by the modulated illumination module through the objective lens to illuminate the sample to be tested, and receive the reflected light reflected from the sample to be tested and then passing through the objective lens, and transmit the reflected light to the photodetector through the aperture, the focusing lens and the pinhole; the photodetector is used to convert the reflected light into an electrical signal, generate a dark field image, and send the dark field image to the industrial computer; the industrial computer is used to perform n-order cross-correlation processing on the signal intensity under the illumination of vortex light of different fractional orders at the same position according to the dark field image generated under vortex light of different fractional orders, and accumulate and sum the results of the n-order cross-correlation processing, calculate the similar parts, and obtain high signal-to-noise ratio data.

6. The dark field confocal microscopy measurement device based on multi-fractional angular momentum demodulation according to claim 5, characterized in that: The size of the aperture matches the central dark spot diameter of the light beam output after beam expansion by the beam expander, and only the central scattered signal is retained.

7. A dark field confocal microscopy measurement method based on multi-fractional angular momentum demodulation, characterized in that: The dark-field confocal microscopy measurement device based on multi-fractional angular momentum demodulation according to any one of claims 1 to 6 is applied, and the dark-field confocal microscopy measurement method based on multi-fractional angular momentum demodulation comprises: The laser is modulated by the first fractional-order vortex phase image to obtain the corresponding fractional-order vortex light; Driving the sample to be tested to move within the field of view of the vortex light to complete scanning of the sample to be tested; Collecting the reflected light reflected from the sample to be tested and generating a dark field image; for any fractional order of the vortex light, a dark field image can be generated; Determining whether all fractional-order vortex phase images have completed the modulation of the laser, and obtaining a first determination result; If the first judgment result is no, the laser is modulated using the next fractional-order vortex phase image to obtain the corresponding fractional-order vortex light, and the process jumps to the step of: driving the sample to be tested to move within the field of view of the vortex light to complete the scanning of the sample to be tested; until all fractional-order vortex phase images have completed the modulation of the laser, and a plurality of dark field images are obtained; If the first judgment result is yes, cross-correlation processing is performed based on the plurality of dark field images to obtain high signal-to-noise ratio data.

8. The dark field confocal microscopy measurement method based on multi-fractional angular momentum demodulation according to claim 7, characterized in that: The laser is modulated by the first fractional-order vortex phase image to obtain the corresponding fractional-order vortex light, specifically including: Control the laser to emit laser; The laser is modulated into vortex light of a corresponding fractional order using a vortex phase diagram of a first fractional order of a two-dimensional optical diffraction element; a plurality of vortex phase diagrams of different fractional orders are etched on the two-dimensional optical diffraction element in a circular arrangement; The laser is modulated using the next fractional-order vortex phase image to obtain the corresponding fractional-order vortex light, specifically including: The two-dimensional optical diffraction element is rotated by a turntable, and the laser is modulated using a vortex phase diagram of the next fractional order of the two-dimensional optical diffraction element.

9. The dark field confocal microscopy measurement method based on multi-fractional angular momentum demodulation according to claim 7, characterized in that: Cross-correlation processing is performed on a plurality of the dark field images to obtain high signal-to-noise ratio data, specifically including: According to the dark field images generated under vortex light of different fractional orders, the signal intensity of the same position under vortex light illumination of different fractional orders is subjected to n-order cross-correlation processing; The results of the n-order cross-correlation processing are accumulated and summed, and similar parts are calculated to obtain high signal-to-noise ratio data.

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