Microscopic speckle interferometry full-field imaging detection device and method

Abstract

The present application relates to a kind of microscopic speckle interferometry full-field imaging detection device, including excitation pulse laser, probe pulse laser and digital pulse delay unit.Pulse laser acts on the heat generated by material surface, thereby exciting ultrasonic pulse signal.Ultrasonic carries the defect structure information of material.On the other hand, light shear speckle interferometry technology uses the speckle field of object surface to be imaged on the surface of digital camera image sensor after passing through shear device.When the measured target is loaded by ultrasonic wave and the surface is slightly deformed, the phase distribution of shear speckle interferogram also changes.The two shear speckle interferograms obtained before and after deformation are directly subtracted, and the light intensity difference or phase difference pattern can be obtained.The distribution of stripe is related to the deformation of measured target, and the surface of measured target can be analyzed according to this, so as to measure the off-plane displacement of object surface caused by internal defect under the condition of ultrasonic wave loading.

Description

Technical Field

[0001] This invention relates to a device and method for quality inspection of semiconductor materials. Specifically, it relates to a microscopic speckle interferometry full-field imaging inspection device and technique. Background Technology

[0002] Silicon wafers are widely used in the semiconductor and microelectronics industries. Using this material, there is a strong need for highly polished, defect-free surfaces to improve the yield and performance of micro-components. Current industry practice involves inspecting wafers for any surface defects only at the end of the final polishing stage. At this stage, subsurface defects are visible as tiny spots forming spiral rings or “vortices” (because they have been exposed by polishing). These subsurface defects are undetectable before the recycling or wafer manufacturing process, resulting in a high rate of “fake” wafers at the end of the finishing stage. Unfortunately, there are currently no instruments available to detect subsurface defects before wafer processing / recycling.

[0003] Several techniques, such as X-ray microscopy, atomic force microscopy, scanning tunneling microscopy, scanning electron microscopy, and acoustic scanning electron microscopy, have been used for surface defect characterization. However, in the semiconductor industry, the main challenge lies in the non-contact, rapid characterization of subsurface and surface defects. Commonly used microscopic measurement techniques can be broadly categorized into contact and non-contact measurements based on whether the measuring instrument is in contact with the device under test during the measurement process. Contact measurements primarily utilize various probe measurement techniques, offering advantages such as high precision, large measurement range, and good repeatability. However, these techniques employ a point-by-point scanning method, resulting in slower measurement speeds and the inability to directly achieve full-field measurements. Non-contact measurements often employ optical methods and various microscopy techniques, offering advantages such as non-contact operation, high sensitivity, and fast measurement speed.

[0004] As a non-contact non-destructive testing technology, electronic shear speckle interferometry is an optical interferometry technique used to measure surface and subsurface defects or surface strain concentrations caused by defects. These defects or strain concentrations are caused by some kind of load, usually thermal, vacuum, or vibration excitation. Electronic shear speckle interferometry has been used to detect hidden defects in aircraft parts, turbine blades, spacecraft, automobiles, and many other products. However, traditional electronic shear speckle interferometry for defect detection has the following problems: (1) limited detection accuracy, mostly on the order of millimeters; (2) thermal, vacuum, or vibration excitation methods are difficult to apply to industrial production lines; (3) the detection results require professional engineers to judge by visual inspection; and (4) it is difficult to obtain information such as the depth, morphology, and size of defects. Summary of the Invention

[0005] The purpose of this invention is to provide a microscopic speckle interferometry full-field imaging detection device, which solves the problem of how to quickly perform full-field imaging.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a full-field imaging detection device for microscopic speckle interferometry, comprising an excitation pulse laser and a probe pulse laser. The laser emitted by the excitation pulse laser passes through an optical isolator I, a half-wave plate I, a polarizing beam splitter I, a beam expander I, and a reflecting mirror I before reaching beam splitter I. There, it meets and overlaps with the laser emitted by the probe pulse laser, which passes through an optical isolator II, a half-wave plate II, a polarizing beam splitter II, a beam expander II, and a reflecting mirror II before reaching beam splitter I. Finally, the laser passes through beam splitter II, a high-magnification zoom system, and an objective lens to reach the sample surface. The remaining portion of the light transmitted through beam splitter II is received by an energy detector, and the reflected light from the sample surface travels along the original path sequentially through… The light passes through the objective lens, high-magnification zoom system, and beam splitter II to beam splitter III. Part of the light reaches the phase shifter, and the other part is transmitted to the shearer. Then, the reflected light from the surfaces of the phase shifter and shearer passes through beam splitter III, plano-convex lens, and filter, leaving only a small amount of laser light emitted by the probe pulse laser to be imaged on the CCD camera. The system also includes a digital pulse delay unit, which controls the delay time between the excitation pulse laser, the probe pulse laser, and the CCD camera. The host computer software on a high-performance computer controls the signal transmission of the digital pulse delay unit and the phase shifter controller, as well as the reception of image information acquired by the CCD camera controller.

[0008] Preferably, the digital pulse delayer has a time resolution on the order of picoseconds and an internal trigger frequency of 10 μHz to 10MHz.

[0009] Preferably, the excitation pulse laser is a nanosecond laser with a wavelength of 1064 nm, and the probe pulse laser is a nanosecond laser with a wavelength of 532 nm.

[0010] Furthermore, optical isolator I, half-wave plate I, and polarizing beam splitter I have high transmittance for light with a wavelength of 1064 nm, while optical isolator II, half-wave plate II, and polarizing beam splitter II have high transmittance for light with a wavelength of 532 nm.

[0011] Preferably, the magnification of the high-magnification zoom system is 0.7 to 6.5 times.

[0012] Preferably, the objective lens is a microscope objective lens, and its type and characteristic parameters can be changed according to different needs.

[0013] Preferably, all optical components are located on the same working horizontal plane.

[0014] Preferably, the phase shifter, shearer, plano-convex lens, filter, and CCD camera are all located directly in front of beam splitter III. The central axes of the phase shifter, beam splitter III, plano-convex lens, filter, and CCD camera are on the same straight line. The central axes of the objective lens, high-magnification zoom system, beam splitter II, beam splitter III, and shearer are on the same straight line, and these two central axes intersect perpendicularly.

[0015] Preferably, the diameter of the spot of the excitation pulse laser focused on the sample surface is much smaller than the diameter of the spot of the probe pulse laser focused on the sample surface.

[0016] A method for full-field imaging detection using microscopic speckle interferometry is also provided, comprising the following steps:

[0017] (a) Turn on the excitation pulse laser, probe pulse laser, digital pulse delayer, phase shifter, and CCD camera;

[0018] (b) Place the sample to be tested on the XYZ three-dimensional displacement stage;

[0019] (c) Adjust beam expander I to change the beam diameter of the excitation pulse laser, adjust the high magnification zoom system, and observe the spot pattern focused on the sample through a CCD camera until a clear focused spot is obtained;

[0020] (d) Adjust the beam expander II to change the beam diameter of the probe pulse laser, adjust the high magnification zoom system, and observe the spot pattern focused on the sample through the CCD camera until a clear spot is obtained;

[0021] (e) Calibrate the energy of the excitation pulse laser using an energy detector;

[0022] (f) Adjust the shearing amount of the shears;

[0023] (g) Open the host computer software of the high-performance computer, maintain serial communication connection with the digital pulse delayer, phase shifter controller, and CCD camera controller, and set the delay time and signal acquisition parameters between the excitation pulse laser, the probe pulse laser and the CCD camera controller, and set the phase shift amount of the phase shifter controller.

[0024] (h) The pattern captured by the CCD camera is calculated and then sent to the intelligent image noise reduction system for noise reduction processing;

[0025] (i) The noise-reduced image is sent to the intelligent target detection system for target identification of material defects;

[0026] (j) Turn off all devices via the control interface.

[0027] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0028] The present invention relates to a microscopic speckle interferometry full-field imaging detection device and method. A pulsed laser acts on the material surface to generate heat, thereby exciting an ultrasonic pulse signal. The ultrasound carries information about the material's defect structure. On the other hand, optical shear speckle interferometry utilizes the speckle field of an object's surface, after passing through a shearing device, to image onto the surface of a digital camera's image sensor. When the target under test is subjected to ultrasonic loading, causing a slight deformation on its surface, the phase distribution of the shear speckle interferogram also changes accordingly. Subtracting the two shear speckle interferograms obtained before and after deformation directly yields the intensity difference or phase difference pattern. The distribution of the fringes is related to the deformation of the target under test; based on this, the deformation of the tested surface can be analyzed, thereby measuring the out-of-surface displacement caused by internal defects on the object's surface under ultrasonic loading. Attached Figure Description

[0029] The following sections will describe some specific embodiments of the invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0030] Figure 1 This is a schematic diagram of the structure of the microscopic speckle interferometry full-field imaging detection device of the present invention;

[0031] Figure 2 This is a flowchart of the microscopic speckle interferometry full-field imaging detection method of the present invention;

[0032] Figure 3 This is the GUI interface of the image intelligent noise reduction system v1.0;

[0033] Figure 4 This is the GUI interface of the LUT-DSSPI intelligent target detection system v1.0;

[0034] Figure 5 It is the control system interface of the host computer software;

[0035] The reference numerals in the attached figures are explained as follows:

[0036] 1. Excitation pulse laser;

[0037] 2. Detection pulsed laser;

[0038] 3. Digital pulse delay unit;

[0039] 4. High-performance computer;

[0040] 5. Beam expander II;

[0041] 6. Half-wave plate II;

[0042] 7. Polarizing beam splitter II;

[0043] 8. Phase shifter controller;

[0044] 9. Beam expander I;

[0045] 10. Reflector I;

[0046] 11. Beam Spectroscope I;

[0047] 12. Phase shifter;

[0048] 13. Cutter;

[0049] 14. CCD camera;

[0050] 15. Optical filters;

[0051] 16. Plano-convex lens;

[0052] 17. Energy detector;

[0053] 18. High-magnification zoom system;

[0054] 19. Objective lens;

[0055] 20. Sample;

[0056] 21. CCD camera controller;

[0057] 22. Half-wave plate I;

[0058] 23. Polarizing beam splitter I;

[0059] 24. Beam Spectroscope II;

[0060] 25. Beam Spectroscope III;

[0061] 26. Optical Isolator I;

[0062] 27. Optical Isolator II;

[0063] 28. Reflector II. Detailed Implementation

[0064] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0066] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0067] Microscopic speckle interferometry full-field imaging detection device, such as Figure 1 The system includes an excitation pulse laser 1 and a probe pulse laser 2. The laser emitted from the excitation pulse laser 1 passes through an optical isolator I 26, a half-wave plate I 22, a polarizing beam splitter I 23, a beam expander I 9, and a reflecting mirror I 10 before reaching the beam splitter I 11. There, it meets and overlaps with the laser emitted from the probe pulse laser 2, which passes through an optical isolator II 27, a half-wave plate II 6, a polarizing beam splitter II 7, a beam expander II 5, and a reflecting mirror II 28 before reaching the beam splitter I 11. Finally, the laser passes through the beam splitter II 24, the high-magnification zoom system 18, and the objective lens 19 to reach the surface of the sample 20. Another portion of the light from the beam splitter II 24 is received by the energy detector 17. The reflected light from the surface of sample 20 passes sequentially along the original path through objective lens 19, high-magnification zoom system 18, beam splitter II 24, and beam splitter III 25. Part of the light reaches phase shifter 12, and the other part is transmitted to shearer 13. Then, the reflected light from the surfaces of phase shifter 12 and shearer 13 passes through beam splitter III 25, plano-convex lens 16, and filter 15, leaving only a small amount of laser light emitted by probe pulse laser 2 to be imaged on CCD camera 14. The delay time between excitation pulse laser 1, probe pulse laser 2, and CCD camera 14 is controlled by digital pulse delayer 3. The host computer software of high-performance computer 4 controls the signal transmission of digital pulse delayer 3 and phase shifter controller 8, as well as the reception of image information acquired by CCD camera controller 21.

[0068] Phase shifter 12, shearer 13, plano-convex lens 16, filter 15, and CCD camera 14 are all located directly in front of beam splitter III 25. The central axes of phase shifter 12, beam splitter III 25, plano-convex lens 16, filter 15, and CCD camera 14 are on the same straight line. The central axes of objective lens 19, high-magnification zoom system 18, beam splitter II 24, beam splitter III 25, and shearer 13 are on the same straight line, and these two central axes intersect perpendicularly.

[0069] like Figure 2 The method for detecting full-field speckle interference using microscopy includes the following steps:

[0070] (a) Turn on the excitation pulse laser 1, the probe pulse laser 2, the digital pulse delay unit 3, the phase shifter 12 and the CCD camera 14;

[0071] (b) Place the sample 20 to be tested on the XYZ three-dimensional displacement stage;

[0072] (c) Adjust the beam expander I9 to change the beam diameter of the excitation pulse laser 1, adjust the high magnification zoom system 18, and observe the spot pattern focused on the sample 20 through the CCD camera 14 until a clear focused spot is obtained.

[0073] (d) Adjust the beam expander II5 to change the beam diameter of the probe pulse laser 2, adjust the high magnification zoom system 18, and observe the spot pattern focused on the sample 20 through the CCD camera 14 until a clear spot is obtained.

[0074] (e) The energy of the excitation pulse laser 1 is calibrated using energy detector 17;

[0075] (f) Adjust the shearing amount of shearer 13;

[0076] (g) Open the host computer software of the high-performance computer 4, set the phase shift of the phase shifter 12 to 0, π / 2, π, and 3π / 2 respectively, and maintain normal serial communication connection with the digital pulse delayer 3, the phase shifter controller 8, and the CCD camera controller 21. Set the delay time, trigger level, trigger frequency, and signal acquisition parameters between the excitation pulse laser 1, the probe pulse laser 2, and the CCD camera controller 21. The specific image acquisition and calculation steps are as follows:

[0077] Before excitation pulse laser loading:

[0078] ① Set the delay times Δt, 2Δt, 3Δt, 4Δt, ... for excitation pulse laser 1 and probe pulse laser 2;

[0079] ② Set the phase shift of phase shifter 12 to 0, and CCD camera 14 takes pictures at each delay time.

[0080] ③ Set the phase shift of phase shifter 12 to π / 2, and CCD camera 14 takes pictures at each delay time.

[0081] ④ Set the phase shift of phase shifter 12 to π, and CCD camera 14 takes pictures at each delay time.

[0082] ⑤ Set the phase shift of phase shifter 12 to 3π / 2, and CCD camera 14 takes pictures at each delay time.

[0083] After the excitation pulse laser is applied:

[0084] Take images following steps ① to ⑤ above;

[0085] ⑥ Calculate the ultrasonic phase field diagrams at different times according to the following formulas;

[0086]

[0087] Where I1, I2, I3, and I4 are the gray intensity matrices of the images corresponding to phases 0, π / 2, π, and 3π / 2 before the excitation pulse laser loading, respectively; and I1', I2', I3', and I4' are the gray intensity matrices of the images corresponding to phases 0, π / 2, π, and 3π / 2 after the excitation pulse laser loading, respectively.

[0088] (h) The image captured by the CCD camera 14 is sent to the image intelligent noise reduction system v1.0 GUI interface for noise reduction processing after step (g);

[0089] (i) The noise-reduced image is sent to the LUT-DSSPI intelligent target detection system for target identification of material defects;

[0090] (j) Turn off all devices via the control interface.

[0091] like Figure 3 This is the GUI interface of the Image Intelligent Noise Reduction System v1.0.

[0092] like Figure 4 This is the GUI interface of the LUT-DSSPI intelligent target detection system v1.0. The photo used in the figure is for illustrative purposes only.

[0093] like Figure 5 It is the control system interface of the host computer software.

[0094] After the light emitted by the excitation pulse laser 1 is focused on the surface of the sample 20, the ultrasonic waves generated by the photoacoustic effect will cause weak vibrations on the surface of the sample 20. Then, according to the shear speckle interference principle, the vibration can be interfered with and imaged to retrieve the surface and internal structure information of the sample.

[0095] Compared with the prior art, the present invention has the following significant features:

[0096] 1. Non-contact semiconductor microscopy non-destructive testing imaging, which can quickly perform full-field imaging without point-by-point scanning;

[0097] 2. Capable of capturing the dynamic propagation process of ultrasonic waves on the surface of materials.

[0098] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A microscopic speckle interferometry full-field imaging detection device, characterized in that: The device includes an excitation pulse laser (1) and a probe pulse laser (2), and also includes an optical isolator I (26), a half-wave plate I (22), a polarizing beam splitter I (23), a beam expander I (9), a reflector I (10), and a beam splitter I (11) disposed in the laser path emitted by the excitation pulse laser (1). The laser path emitted by the probe pulse laser (2) includes an optical isolator II (27), a half-wave plate II (6), and a polarizing beam splitter II (7). The beam expander II (5), the reflector II (28), and the beam splitter I (11) are connected. The laser light after the beam splitter I (11) passes sequentially through the beam splitter II (24), the high-magnification zoom system (18), and the objective lens (19) to reach the surface of the sample (20). Another part of the light passing through the beam splitter II (24) is received by the energy detector (17). The reflected light from the surface of the sample (20) passes sequentially along the original path through the objective lens (19), the high-magnification zoom system (18), and the beam splitter II (24) to the sample (20). A portion of the light reaches the phase shifter (12) via the beam splitter III (25), while the other portion is transmitted to the shearer (13). The reflected light from the surfaces of the phase shifter (12) and the shearer (13) then passes through the beam splitter III (25), the plano-convex lens (16), and the filter (15), leaving only a small amount of laser light emitted by the probe pulse laser (2) to be imaged on the CCD camera (14). The system also includes a digital pulse delay unit (3), which controls the delay time between the excitation pulse laser (1), the probe pulse laser (2), and the CCD camera (14). The system also controls the signal transmission of the digital pulse delay unit (3) and the phase shifter controller (8) and the image information collected by the CCD camera controller (21) through the host computer software of the high-performance computer (4). The diameter of the spot of the excitation pulse laser (1) focused on the surface of the sample (20) is much smaller than the diameter of the spot of the probe pulse laser (2) focused on the surface of the sample (20).

2. The microscopic speckle interferometry full-field imaging detection device according to claim 1, characterized in that: The digital pulse delay unit (3) has a time resolution on the order of picoseconds and an internal trigger frequency of 10 μHz to 10 MHz.

3. The microscopic speckle interferometry full-field imaging detection device according to claim 1, characterized in that: The excitation pulse laser (1) is a nanosecond laser with a wavelength of 1064 nm, and the probe pulse laser (2) is a nanosecond laser with a wavelength of 532 nm.

4. The microscopic speckle interferometry full-field imaging detection device according to claim 3, characterized in that: Optical isolator I (26), half-wave plate I (22) and polarizing beam splitter I (23) have high transmittance for light with a wavelength of 1064 nm, while optical isolator II (27), half-wave plate II (6) and polarizing beam splitter II (7) have high transmittance for light with a wavelength of 532 nm.

5. The microscopic speckle interferometry full-field imaging detection device according to claim 1, characterized in that: The magnification of the high-magnification zoom system (18) is 0.7 to 6.5 times.

6. The full-field imaging detection device for microscopic speckle interferometry according to claim 1, characterized in that: The objective lens (19) is a microscope objective lens, and its type and characteristic parameters can be changed according to different needs.

7. The microscopic speckle interferometry full-field imaging detection device according to claim 1, characterized in that: All optical components are located on the same working horizontal plane.

8. The microscopic speckle interferometry full-field imaging detection device according to claim 1, characterized in that: The phase shifter (12), shearer (13), plano-convex lens (16), filter (15) and CCD camera (14) are all located directly in front of beam splitter III (25). The central axes of the phase shifter (12), beam splitter III (25), plano-convex lens (16), filter (15) and CCD camera (14) are on the same straight line. The central axes of the objective lens (19), high magnification zoom system (18), beam splitter II (24), beam splitter III (25) and shearer (13) are on the same straight line, and these two central axes intersect perpendicularly.

9. A method for detecting full-field microspeckle interference using the microspeckle interference full-field imaging device of claim 1, characterized in that, Includes the following steps: (a) Turn on the excitation pulse laser (1), the probe pulse laser (2), the digital pulse delay (3), the phase shifter (12), and the CCD camera (14). (b) Place the sample (20) to be tested on the XYZ three-dimensional displacement stage; (c) Adjust the beam expander I (9) to change the beam diameter of the excitation pulse laser (1), adjust the high magnification zoom system (18), and observe the spot pattern focused on the sample (20) through the CCD camera (14) until a clear focused spot is obtained; (d) Adjust the beam expander II (5) to change the beam diameter of the probe pulse laser (2), adjust the high magnification zoom system (18), and observe the spot pattern focused on the sample (20) through the CCD camera (14) until a clear spot is obtained; (e) The energy of the excitation pulse laser (1) is calibrated using the energy detector (17); (f) Adjust the shearing amount of the shearer (13); (g) Open the host computer software of the high-performance computer (4), maintain serial communication connection with the digital pulse delay unit (3), the phase shifter controller (8), the CCD camera controller (21), and set the delay time and signal acquisition parameters between the excitation pulse laser (1), the probe pulse laser (2) and the CCD camera controller (21), and set the phase shift amount of the phase shifter controller (8); (h) The pattern captured by the CCD camera (14) is calculated and then sent to the image intelligent noise reduction system for noise reduction processing; (i) The noise-reduced image is sent to the intelligent target detection system for target identification of material defects; (j) Turn off all devices via the control interface.

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