A bright-dark field fusion harmonic microscopic imaging device and method

Abstract

This invention relates to a bright-field and dark-field fusion harmonic microscopy imaging device and method for detecting defects in two-dimensional semiconductor crystals, belonging to the field of optical microscopy imaging technology. The device comprises a laser source system, a harmonic signal excitation system, a bright-field signal detection system, a dark-field signal detection system, and a control and data processing system. This invention uses a dark-field spatial filter to filter out bright-field illumination harmonic signals to collect large-wavelength dark-field radiation harmonic signals, and employs a mode of simultaneous detection and fusion of bright-field and dark-field harmonic microscopic images for crystal defect detection. This invention utilizes the harmonic signal interference effect of crystal defects with different orientations, and displays crystal defects and defect edges as high-contrast images through large-angle harmonic radiation and bright-field and dark-field harmonic image fusion. The beneficial effects of this invention are: improved sensitivity and signal-to-noise ratio in two-dimensional semiconductor crystal defect detection.

Description

Technical Field

[0001] This invention belongs to the field of optical microscopy and measurement, and mainly relates to a bright-dark field fusion harmonic microscopy imaging device and method for detecting defects in two-dimensional semiconductor crystals. Background Technology

[0002] The main bottleneck in fabricating complex chips using two-dimensional semiconductor materials lies in the wafer-level fabrication of highly uniform, grain-oriented monolayer two-dimensional semiconductors, which is crucial for improving transistor yield. In monolayer two-dimensional semiconductor wafers, inconsistencies in crystal orientation and small grain size lead to numerous non-uniformly distributed crystal defects, resulting in reduced photoelectric properties and uniformity. Grain boundaries in the channel region cause carrier scattering, thereby reducing carrier mobility, device on / off ratio, and other performance characteristics. Therefore, rapid, highly sensitive, and high-contrast detection of crystal defects in monolayer two-dimensional semiconductors is essential for their adoption as next-generation chip materials.

[0003] Currently, various techniques are used to characterize crystal defects in these two-dimensional semiconductors to assess sample crystal quality. Transmission electron microscopy directly resolves the atomic details of defects, but requires complex and destructive sample preparation procedures. Photoluminescence and Raman spectroscopy enable rapid and non-destructive detection of the electronic and vibrational properties of crystal defect regions. Compared to the signal response of the original crystal, crystal defect regions typically exhibit enhanced or suppressed redshifts or blueshifts, depending on factors such as material composition, doping level, defect passivation, and crystal defect geometry. These factors complicate the above detection methods as reproducible defect characterization techniques. Therefore, there is an urgent need for a more reliable and convenient detection method to effectively image crystal defects and edges, unaffected by composition, doping, and defects. Dark-field microscopy improves image contrast by suppressing light scattered from uniform regions. This technique does not rely on detailed local atomic and electronic structures; that is, sharp discontinuities show higher contrast. Under the same incident and collected light frequencies, edges can be clearly seen in dark-field optical images of two-dimensional semiconductors, while they are not observable in conventional bright-field optical images. However, current traditional optical imaging techniques cannot resolve crystal defects in two-dimensional semiconductors because the in-plane linear dielectric response of two-dimensional semiconductors is isotropic. Therefore, the radiative dipoles generated by two grains separated by crystal defects always maintain the same phase. Even if their scattered light intensities are very close in dark-field imaging, crystal defects cannot be detected or distinguished.

[0004] Therefore, a pressing technical problem that needs to be solved by those skilled in the art is how to perform high-contrast, high-sensitivity detection of defects in two-dimensional semiconductor crystals. Summary of the Invention

[0005] To address the above problems, the present invention provides a bright-dark field fusion harmonic microscopy imaging device, comprising:

[0006] A laser source system is used to generate harmonic signal excitation light, which is used to excite a sample placed on a three-dimensional displacement stage;

[0007] The harmonic signal excitation system is set in the output optical path of the laser source system and is used to scan the excitation beam on the sample surface and excite harmonic signals.

[0008] A bright-field signal detection system is used to acquire and detect harmonic signals excited by the harmonic signal excitation system in bright-field mode.

[0009] A dark field signal detection system is used for spatial separation of harmonic signals, and to acquire and detect harmonic signals excited by the harmonic signal excitation system in dark field scattering mode.

[0010] The control and data processing system is used to perform timing control and light-dark field fusion harmonic microscopy imaging device, control the light-dark field detection mode, and process the harmonic signal according to the detection mode adopted to obtain the light-dark field fusion harmonic microscopy image of the sample.

[0011] In this technical solution, by adding a dark-field harmonic microscopy imaging system to the bright-field harmonic detection mode, multiple modes of harmonic microscopy imaging detection are realized. The dark-field spatial filter is used to filter out the bright-field illumination harmonic signal to collect the large-wave vector dark-field radiation harmonic signal for dark-field harmonic detection, thereby improving the contrast of harmonic microscopy imaging and the sensitivity of two-dimensional semiconductor crystal defect detection.

[0012] Furthermore, the laser source system includes a femtosecond laser source, a first lens, a second lens, and a dichroic mirror. The first lens is disposed in the output light path of the femtosecond laser source, and the second lens is disposed in the output light path of the first lens. The distance between the two lenses is the sum of their focal lengths. By designing the ratio of the focal lengths of the first lens and the second lens, the size of the output beam of the laser source system can be controlled. The dichroic mirror is disposed in the output light path of the second lens. The separation wavelength of the dichroic mirror is between the output wavelength of the femtosecond laser source and the wavelength of the harmonic signal.

[0013] In this technical solution, the laser output beam is collimated and expanded so that the spot size is matched with the size of the beam scanning unit, the objective lens entrance pupil, and the dark field spatial filter.

[0014] Furthermore, the harmonic signal excitation system includes a beam scanning element, a scanning lens, a tube mirror, a polarization conversion module, and a focusing objective. The scanning lens is located on the outgoing light path of the beam scanning element, and its entrance pupil is located on the scanning plane of the beam scanning element. The tube mirror is located on the outgoing light path of the scanning lens, the polarization conversion module is located on the outgoing light path of the tube mirror, and the focusing objective is located on the outgoing light path of the polarization conversion module.

[0015] In this technical solution, a large field of view detection of the sample can be achieved through two-dimensional beam scanning.

[0016] Furthermore, the bright-field signal detection system includes a collecting objective lens, a first harmonic signal filtering module, a first focusing lens, and a first harmonic signal detector. The passband of the first harmonic signal filtering module matches the wavelength of the harmonic signal, and the filtering density can be increased according to the filtering requirements.

[0017] In this technical solution, by setting a bright-field harmonic imaging system in the forward scattering direction, the intensity of the harmonic signal is improved. At the same time, the first harmonic signal filtering module is used to filter out the excitation light to the maximum extent, thereby improving the contrast of the bright-field harmonic signal.

[0018] Furthermore, the dark field signal detection system includes a second harmonic signal filtering module, a beam splitter, a dark field spatial filter, a second focusing lens, a second harmonic signal detector, a third focusing lens, and a high-sensitivity camera. The size of the dark field spatial filter can be adjusted according to the incident light spot size and the collection angle of the dark field scattered harmonic signal wave vector.

[0019] In this technical solution, a dark field spatial filter is used to filter out bright field harmonic signals, thereby extracting dark field harmonic signals scattered at large angles for imaging, thus improving the imaging contrast of crystal defects.

[0020] Furthermore, the control and data processing system is communicatively connected to the beam scanning element of the harmonic signal excitation system, the control and data processing system is communicatively connected to the first harmonic signal detector of the bright field signal detection system, and the control and data processing system is communicatively connected to the second harmonic signal detector and the high-sensitivity camera of the dark field signal detection system.

[0021] In this technical solution, the timing control of the bright-field and dark-field harmonic microscopy imaging device is optimized by communicating with other systems through the control and data processing system, thereby realizing the synchronous detection of bright-field and dark-field harmonic microscopy images.

[0022] This invention also proposes a bright-dark field fusion harmonic microscopy imaging method, based on the bright-dark field fusion harmonic microscopy imaging device described above, comprising the following steps:

[0023] (1) The laser source system emits harmonic signals to excite light, and the size of the output beam is adjusted;

[0024] (2) The harmonic signal excitation system uses the excitation light after the beam size is adjusted to scan the sample, excite the sample to generate harmonic signals, and at the same time the focusing objective lens collects the harmonic signals, and the harmonic signals are returned to the dichroic mirror for filtering.

[0025] (3) The bright field signal detection system uses a collecting objective lens to collect forward-scattered harmonic signals, which are then filtered and detected by the first harmonic signal detector.

[0026] (4) The dark field signal detection system receives the backscattered harmonic signal from the dichroic mirror filter and filters out the bright field illumination harmonic signal through the dark field space filter to collect the large-wave vector dark field scattered harmonic signal. After filtering, it is detected by the second harmonic signal detector.

[0027] (5) The control and data processing system processes the bright field and dark field harmonic signals detected by the bright field signal detection system and the dark field signal detection system to generate a bright and dark field fused harmonic image of the sample.

[0028] In this technical solution, by utilizing the complementary characteristics of bright-field and dark-field harmonic images and designing dark-field spatial filter parameters, bright-field illumination harmonic signals are filtered out and large-wave vector dark-field radiation harmonic signals are collected. Thus, large-angle harmonic radiation is used to display crystal defects and defect edges as high-contrast images.

[0029] Furthermore, the bright-field and dark-field detection systems simultaneously generate bright-field and dark-field harmonic microscopic images using forward and backscattered harmonic signals, respectively, and perform image fusion by extracting crystal defects and edge features.

[0030] In this technical solution, the information richness and detection sensitivity of crystal defect harmonic images are further improved by organically fusing bright and dark field harmonic microscopy and image fusion registration. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the principle of the bright-dark field fusion harmonic microscopy imaging device in the embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the structure of the bright-dark field fusion harmonic microscopy imaging device in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the dark field spatial filter in an embodiment of the present invention.

[0034] Figure 4 This is a flowchart of the bright-dark field fusion harmonic microscopy imaging method in an embodiment of the present invention.

[0035] The system includes: 1-Laser source system; 101-Femtosecond laser source; 102-First lens; 103-Second lens; 104-Dichroic mirror; 2-Harmonic signal excitation system; 201-Beam scanning element; 202-Scanning lens; 203-Tube mirror; 204-Polarization conversion module; 205-Focusing objective; 3-Sample; 4-Bright field signal detection system; 401-Collection objective; 402-First harmonic signal filtering module; 403-First focusing lens; 404-First harmonic signal detector; 5-Dark field signal detection system; 501-Second harmonic signal filtering module; 502 Beam splitter; 503-Dark field spatial filter; 504-Second focusing lens; 505-Second harmonic signal detector; 506-Third focusing lens; 507-High-sensitivity camera; 6-Control and data processing system. Detailed Implementation

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in sequences other than those illustrated or described herein.

[0038] Reference Figure 1 and 2 As shown, this invention proposes a bright-dark field fusion harmonic microscopy imaging device.

[0039] Laser source system 1 is used to generate harmonic signal excitation light, which is used to excite sample 3 placed on a three-dimensional displacement stage;

[0040] The harmonic signal excitation system 2 is set in the output optical path of the laser source system and is used to scan the excitation beam on the sample surface and excite harmonic signals.

[0041] Bright-field signal detection system 4 is used to acquire and detect harmonic signals excited by the harmonic signal excitation system in bright-field mode;

[0042] Dark field signal detection system 5 is used for spatial separation of harmonic signals, and to collect and detect harmonic signals excited by the harmonic signal excitation system in dark field scattering mode;

[0043] The control and data processing system 6 is used to perform timing control and brightness and darkness field fusion harmonic microscopy imaging device, control the brightness and darkness field detection mode, and process the harmonic signal according to the detection mode adopted to obtain the brightness and darkness field fusion harmonic microscopy image of the sample.

[0044] In related technologies, traditional optical imaging cannot resolve crystal defects in two-dimensional semiconductors. In traditional linear dark-field imaging, the intensity of scattered light is very close, and crystal defects cannot be detected or distinguished.

[0045] Based on this, this embodiment proposes a bright-dark field fusion harmonic microscopy imaging device, referring to... Figure 1 and 2 As shown, it includes a laser source system 1 for generating harmonic signal excitation light with adjustable spot size. The harmonic signal excitation light excites sample 3 via harmonic signal excitation system 2. The harmonic signals radiated by sample 3 are synchronously collected and detected by bright field signal detection system 4 and dark field signal detection system 5, thereby enabling bright and dark field imaging or corresponding processing of the harmonic signals radiated by sample 3.

[0046] Typically, after controlling the spot size of the excitation light, the beam is focused and scanned on the sample to generate harmonic signals. The harmonic signal excitation system 2 is positioned on the output optical path of the laser source system 1, and utilizes a beam scanning element in conjunction with corresponding optical elements to achieve focused scanning excitation of the harmonic signals.

[0047] Normally, harmonic signals can be detected in the forward or backward direction. The bright field signal detection system 4 is used to collect and detect the harmonic signals excited by the harmonic signal excitation system 2 in the bright field mode. Specifically, the bright field detection of harmonic signals can be performed in the forward scattering mode.

[0048] Dark field signal detection system 5 is used to collect and detect harmonic signals excited by the harmonic signal excitation system 2 in dark field mode. Specifically, it can collect large-angle scattered signals in backscattering mode to perform harmonic signal dark field detection.

[0049] The bright-field and dark-field fusion harmonic microscopy imaging system also includes a control and data processing system 6, which is communicatively connected to the beam scanning element 201 of the harmonic signal excitation system 2 to realize the timing control of rapid beam scanning. The control and data processing system 6 is communicatively connected to the first harmonic signal detector 404 of the bright-field signal detection system 4 to realize high-speed bright-field acquisition and detection of harmonic signals. The control and data processing system 6 is communicatively connected to the second harmonic signal detector 505 and the high-sensitivity camera 507 of the dark-field signal detection system 5 to realize beam alignment of the dark-field spatial filter and synchronous acquisition and detection of backscattered harmonic signals in the dark field.

[0050] In an optional embodiment of the present invention, the laser source system 1 includes a femtosecond laser source 101, a first lens 102, a second lens 103, and a dichroic mirror 104. The first lens 102 is disposed in the output light path of the femtosecond laser source 101, and the second lens 103 is disposed in the output light path of the first lens 102, with the distance between the two being the sum of their focal lengths. By designing the ratio of the focal lengths of the first lens 102 and the second lens 103, the size control of the output beam of the laser source system 1 is achieved. The dichroic mirror 104 is disposed in the output light path of the second lens 103, and the separation wavelength of the dichroic mirror 104 is between the output wavelength of the femtosecond laser source 101 and the harmonic signal wavelength.

[0051] Reference Figure 2 and 3 As shown, in this embodiment, the harmonic signal excitation system 2 includes a beam scanning element 201, a scanning lens 202, a tube mirror 203, a polarization conversion module 204, and a focusing objective lens 205. The scanning lens 202 is located on the exit light path of the beam scanning element 201, and its entrance pupil is located on the scanning plane of the beam scanning element 201. The tube mirror 203 is located on the exit light path of the scanning lens 202, the polarization conversion module 204 is located on the exit light path of the tube mirror 203, and the focusing objective lens 205 is located on the exit light path of the polarization conversion module 204. The advantage of using beam scanning to achieve sample scanning is that it makes the system compact and economical.

[0052] In this embodiment, the bright field signal detection system 4 includes a collecting objective lens 401, a first harmonic signal filtering module 402, a first focusing lens 403, and a first harmonic signal detector 404. The passband of the first harmonic signal filtering module 402 is matched with the wavelength of the harmonic signal, and the optical density of the filtering module can be increased according to the filtering requirements.

[0053] In an optional embodiment of the present invention, the dark field signal detection system 5 includes a second harmonic signal filtering module 501, a beam splitter 502, a dark field spatial filter 503, a second focusing lens 504, a second harmonic signal detector 505, a third focusing lens 506, and a high-sensitivity camera 507.

[0054] In this embodiment, the size of the dark field spatial filter can be adjusted according to the incident light spot size and the collection angle of the dark field scattered harmonic signal wave vector.

[0055] Reference Figure 4 The present invention also proposes a bright-dark field fusion harmonic microscopy imaging method, based on the above-mentioned bright-dark field fusion harmonic microscopy imaging device, comprising the following steps:

[0056] S1 generates excitation light; adjust the power and beam size.

[0057] S2 scans the sample to generate harmonic signals;

[0058] S3 collects harmonic images of bright-field detection mode;

[0059] S4 collects harmonic images of dark field detection mode;

[0060] S5 performs fusion processing on the harmonic images from the two detection modes.

[0061] In an optional embodiment of the present invention, bright-field and dark-field harmonic microscopic images are generated simultaneously using forward and backscattered harmonic signals, and image fusion is performed by extracting crystal defects and edge features.

[0062] The above provides a detailed description of the bright-dark field fusion harmonic microscopy imaging device and method proposed in this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments are merely for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. These changes should all fall within the protection scope of the appended claims. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A bright-dark field fusion harmonic microscopic imaging method using a bright-dark field fusion harmonic microscopic imaging apparatus, characterized by, The device includes: a laser source system (1) for generating harmonic signal excitation light, which is used to excite a sample (3) placed on a three-dimensional displacement stage; a harmonic signal excitation system (2) disposed on the output light path of the laser source system (1) for scanning the excitation beam on the sample surface and exciting harmonic signals; a bright field signal detection system (4) for acquiring and detecting the harmonic signals excited by the harmonic signal excitation system (2) in bright field mode; a dark field signal detection system (5) for spatial separation of harmonic signals, acquiring and detecting the harmonic signals excited by the harmonic signal excitation system (2) in dark field scattering mode; and a control and data processing system (6) for timing control of the bright and dark field fusion harmonic microscopy imaging device, control of the bright and dark field detection mode, and processing of the harmonic signals according to the detection mode adopted to obtain a bright and dark field fusion harmonic microscopy image of the sample (3). The above-mentioned device operates using the following steps: (1) Laser source system (1) Output harmonic signal to excite light, and adjust the size of the output beam; (2) Harmonic signal excitation system (2) uses the excitation light after the beam size adjustment to scan the sample, excite the sample to generate harmonic signals, and at the same time the focusing objective (205) collects the harmonic signals, and the harmonic signals are returned to the dichroic mirror (104) for filtering; (3) Bright field signal detection system (4) collects forward-scattered harmonic signals using a collecting objective lens (401), and after filtering, they are detected by the first harmonic signal detector (404); (4) Dark field signal detection system (5) receives backscattered harmonic signals filtered by dichroic mirror (104) and filters out bright field illumination harmonic signals by dark field space filter (503) to collect large-wave vector dark field scattered harmonic signals, which are then detected by second harmonic signal detector (505) after filtering. (5) The control and data processing system (6) processes the bright field and dark field harmonic signals detected by the bright field signal detection system (4) and the dark field signal detection system (5) to generate a bright and dark field fused harmonic image of the sample. Among them, bright-field and dark-field harmonic microscopic images are generated simultaneously using forward and backscattered harmonic signals, and image fusion is performed by extracting crystal defects and edge features.

2. The method according to claim 1, wherein, The laser source system (1) includes a femtosecond laser source (101), a first lens (102), a second lens (103), and a dichroic mirror (104). The first lens (102) is disposed on the output light path of the femtosecond laser source (101), and the second lens (103) is disposed on the output light path of the first lens (102). The distance between the two lenses is the sum of their focal lengths. By designing the ratio of the focal lengths of the first lens (102) and the second lens (103), the size control of the output beam of the laser source system (1) is achieved. The dichroic mirror (104) is disposed on the output light path of the second lens (103). The separation wavelength of the dichroic mirror (104) is between the output wavelength of the femtosecond laser source (101) and the wavelength of the harmonic signal.

3. The method according to claim 1, wherein, The harmonic signal excitation system (2) includes a beam scanning element (201), a scanning lens (202), a tube mirror (203), a polarization conversion module (204), and a focusing objective (205). The scanning lens (202) is located on the outgoing light path of the beam scanning element (201), and the entrance pupil is located on the scanning plane of the beam scanning element (201). The tube mirror (203) is located on the outgoing light path of the scanning lens (202). The polarization conversion module (204) is located on the outgoing light path of the tube mirror (203). The focusing objective (205) is located on the outgoing light path of the polarization conversion module (204).

4. The method according to claim 1, wherein, The bright field signal detection system (4) includes a collecting objective lens (401), a first harmonic signal filtering module (402), a first focusing lens (403), and a first harmonic signal detector (404). The passband of the first harmonic signal filtering module (402) is matched with the wavelength of the harmonic signal, and the filtering density can be increased according to the filtering requirements.

5. The method according to claim 1, wherein, The dark field signal detection system (5) includes a second harmonic signal filter module (501), a beam splitter (502), a dark field spatial filter (503), a second focusing lens (504), a second harmonic signal detector (505), a third focusing lens (506), and a high-sensitivity camera (507).

6. The method according to claim 5, wherein the method is a bright-dark field fusion harmonic microscopy method. The size of the dark field spatial filter can be adjusted according to the incident light spot size and the collection angle of the dark field scattered harmonic signal wave vector.

7. The bright-dark field fusion harmonic microscopy imaging method according to any one of claims 1-6, characterized in that, The control and data processing system (6) is communicatively connected to the beam scanning element (201) of the harmonic signal excitation system (2), the control and data processing system (6) is communicatively connected to the first harmonic signal detector (404) of the bright field signal detection system (4), and the control and data processing system (6) is communicatively connected to the second harmonic signal detector (505) and the high-sensitivity camera (507) of the dark field signal detection system (5).

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