A scanning transmission imaging device in a scanning electron microscope

Abstract

The present invention discloses a scanning transmission imaging device in a scanning electron microscope, including a sample stage, a fixing seat, a support frame and a backscattered electron probe; the sample stage is arranged at the top of the support frame, and is used to fix the sample to be observed; the backscattered electron probe is arranged on the fixing seat, and is used to receive the transmission scattered electrons passing through the sample to be observed; the fixing seat is arranged in the support frame and is connected to the support frame, and is used to adjust the distance between the backscattered electron probe and the sample stage. The present invention uses the backscattered electron probe provided by the scanning electron microscope as the transmission scattered electron signal detector, and there is no need to purchase STEM accessories separately, which can greatly reduce the cost of upgrading the scanning electron microscope to the scanning transmission imaging function; the fixing seat can slide up and down in the support frame, thereby changing the size of the transmission scattered electron receiving angle, and realizing the collection of high and low angle annular dark field images. The present invention can significantly reduce the damage of the electron beam to the sample to be observed, and is suitable for the transmission analysis of samples with poor resistance to electron beam irradiation.

Description

Technical Field

[0001] The invention discloses a scanning transmission imaging device in a scanning electron microscope, belonging to the technical field of scanning transmission electron microscopy. Background Art

[0002] Scanning transmission electron microscopy is an imaging technology that uses a magnetic lens to focus an electron beam onto the surface of a thin sample for scanning, and obtains information about the internal microstructure of the sample by collecting transmitted electron signals. The scanning transmission electron microscope (STEM) manufactured using this technology has become an indispensable instrument for characterizing the microstructure of matter. STEM is an electron microscopy technology developed based on the demand for high-resolution imaging. In order to obtain a higher resolution, its acceleration voltage is generally 200 to 300 kV. Due to the high energy of the electron beam, it is not suitable for observing samples with poor resistance to electron beam irradiation.

[0003] The acceleration voltage of the scanning electron microscope (SEM) is relatively low, generally not exceeding 30kV. If a STEM device is installed in the SEM, the damage to the sample by the electron beam can be significantly reduced. It is particularly suitable for transmission analysis of soft material samples such as organic polymers and biological materials. The difference between STEM and SEM is that STEM uses thin samples and installs a detector under the sample. When the electron beam scans a certain position of the sample, the detector will synchronously receive the signal and convert it into current intensity to display on the computer screen. Each point on the sample corresponds to the generated image point one by one. In recent years, with the improvement of SEM performance and the popularization of field emission SEM, the demand for expanding STEM functions on SEM has become more and more urgent.

[0004] The method of realizing STEM function on SEM is usually to install a separately made STEM accessory in the SEM. STEM accessories include a thin sample holder and a detector under the sample for receiving scanning transmission signals. The price of STEM accessories is relatively expensive, about 100,000 to 300,000 RMB, which makes the cost of upgrading the scanning transmission imaging function of SEM high, which is not conducive to large-scale promotion and application. Summary of the invention

[0005] The purpose of the present application is to provide a scanning transmission imaging device in a scanning electron microscope to solve the technical problem of high upgrading and reconstruction cost of the scanning electron microscope caused by installing a separately manufactured STEM accessory in the scanning electron microscope in the prior art.

[0006] The present invention provides a scanning transmission imaging device in a scanning electron microscope, comprising a sample stage, a fixing seat, a supporting frame and a backscattered electron probe;

[0007] The sample stage is arranged at the top of the support frame and is used to fix the sample to be observed;

[0008] The backscattered electron probe is arranged on the fixing seat and is used to receive transmission scattered electrons passing through the sample to be observed;

[0009] The fixing seat is arranged in the supporting frame and connected to the supporting frame, and is used for adjusting the distance between the backscattered electron probe and the sample stage.

[0010] Preferably, the support frame comprises a frame body, a sample stage groove, a slide rail groove and a first fixing screw;

[0011] The sample stage groove is opened at the top of the frame body, a transmission through hole is arranged in the sample stage groove, and the sample stage is arranged in the sample stage groove;

[0012] The slide rail grooves are arranged on opposite sides of the frame;

[0013] The first fixing screw passes through the slide rail slot and is connected to the fixing base, so as to fix the fixing base on the frame.

[0014] Preferably, the support frame further comprises an elastic pressing sheet, and the elastic pressing sheet is arranged at the top end of the frame body;

[0015] One end of the elastic pressing sheet is fixedly connected to the top of the frame, and the other end is arranged on the sample stage, and is used to fix the sample stage in the groove of the sample stage;

[0016] The bottom end of the frame is provided with a connection hole connected with the sample stage base of the scanning electron microscope.

[0017] Preferably, the sample stage comprises a support sheet and a cover sheet;

[0018] A sample groove is provided on the first surface of the support sheet, and the sample groove is used to carry the sample to be observed;

[0019] The cover sheet is fixed on the support sheet, and the first surface of the cover sheet is connected to the sample to be observed, so as to fix the sample to be observed in the sample groove.

[0020] Preferably, a first funnel-shaped groove is opened on the second surface of the support sheet, the first funnel-shaped groove is connected to the sample groove, and the diameter of the first funnel-shaped groove on the second surface of the support sheet is larger than the diameter of the first funnel-shaped groove at the connection with the sample groove.

[0021] Preferably, a second funnel-shaped groove is formed on the second surface of the cover sheet, and a diameter of the second funnel-shaped groove on the second surface of the cover sheet is larger than a diameter of the second funnel-shaped groove on the first surface of the cover sheet.

[0022] Preferably, a fixing groove is provided on the fixing seat, and the fixing groove is used to fix the backscattered electron probe;

[0023] The bosses on the opposite sides of the fixing groove are provided with first threaded holes;

[0024] The first fixing screw passes through the slide rail groove and the first threaded hole in sequence to fix the fixing seat on the frame.

[0025] Preferably, a transmission hole is provided on the fixing groove, and the inner hole of the backscattered electron probe matches the transmission hole.

[0026] Preferably, second threaded holes are provided on the bosses on opposite sides of the fixing groove;

[0027] The second fixing screw passes through the second threaded hole and is connected to the backscattered electron probe in the fixing groove, so as to fix the backscattered electron probe.

[0028] Preferably, the fixing seat is made of plastic;

[0029] The sample stage and the support frame are made of aluminum alloy.

[0030] Compared with the prior art, the scanning transmission imaging device in the scanning electron microscope of the present invention has the following beneficial effects:

[0031] The scanning transmission imaging device in the scanning electron microscope of the present invention uses the backscattered electron probe of the scanning electron microscope as the transmission scattered electron signal detector, and does not need to purchase STEM accessories separately, which can greatly reduce the cost of upgrading the scanning transmission imaging function of the scanning electron microscope. The scanning transmission imaging device in the scanning electron microscope of the present invention can significantly reduce the damage of the electron beam to the sample to be observed, and is particularly suitable for the transmission analysis of soft material samples such as organic polymers and biological materials.

[0032] The fixing seat of the backscattered electron probe of the present invention can slide up and down in the supporting frame. By adjusting the distance between the backscattered electron probe and the sample stage, the size of the transmission scattered electron receiving angle can be changed, thereby realizing the collection of high-angle annular dark field images (High-Angle Annular Dark-Field Imaging, HAADF) and low-angle annular dark field images (Low-Angle Annular Dark-Field Imaging, LAADF), so that the obtained image can more accurately reflect the structure and composition information of the sample to be observed.

[0033] The sample stage of the present invention can be flexibly disassembled and assembled, and the sample can be replaced outside the electron microscope and then fixed to the support frame, which can greatly shorten the time for replacing the sample.

[0034] The sample stage of the present invention has funnel-shaped grooves on the top and bottom, which will not block the transmission electron signal and the secondary electron signal, so the scanning transmission image and the secondary electron image of the sample to be observed can be collected at the same time.

[0035] The backscattered electron probe of the present invention is an annular structure, and the diameter of its inner hole is slightly larger than the sample diameter. Transmission scattered electrons with a smaller scattering angle can pass through the inner hole, and transmission scattered electrons with a larger scattering angle will be collected by the annular probe to form an annular dark field image (Annular Dark-Field Imaging, ADF). Since transmission scattered electrons with a smaller scattering angle will not directly irradiate the signal detection surface of the backscattered electron probe, the problem of signal oversaturation can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A three-dimensional diagram of a scanning transmission imaging device in a scanning electron microscope in an embodiment of the present invention at one angle;

[0037] Figure 2 A three-dimensional diagram of a scanning transmission imaging device in a scanning electron microscope in an embodiment of the present invention at another angle;

[0038] Figure 3 A half-section diagram of a scanning transmission imaging device in a scanning electron microscope in an embodiment of the present invention;

[0039] Figure 4 This is a front view of a support frame in an embodiment of the present invention;

[0040] Figure 5 for Figure 4 AA section diagram in;

[0041] Figure 6 It is a right side view of the support frame in the embodiment of the present invention;

[0042] Figure 7 This is a front view of a support sheet in an embodiment of the present invention;

[0043] Figure 8 is a top view of a support sheet in an embodiment of the present invention;

[0044] Fig. 9 is a front view of a cover sheet in an embodiment of the present invention;

[0045] Fig.10 is a top view of a cover sheet according to an embodiment of the present invention;

[0046] Fig.11 It is a structural schematic diagram of a fixing base in an embodiment of the present invention;

[0047] Fig.12 for Fig.11 Schematic diagram of the BB cross section.

[0048] List of parts and reference numerals:

[0049] 1 is a sample stage; 11 is a support plate; 111 is a sample groove; 112 is a first funnel-shaped groove; 12 is a cover plate; 121 is a second funnel-shaped groove; 2 is a fixing seat; 21 is a fixing groove; 22 is a first threaded hole; 23 is a transmission hole; 24 is a second threaded hole; 25 is a boss; 3 is a support frame; 31 is a frame body; 32 is a sample stage groove; 33 is a slide rail groove; 34 is a first fixing screw; 35 is an elastic pressing sheet; 36 is a connecting hole; 37 is a transmission through hole. DETAILED DESCRIPTION

[0050] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0051] like Figures 1 to 3 As shown, the scanning transmission imaging device in the scanning electron microscope of the embodiment of the present invention includes a sample stage 1, a fixing seat 2, a support frame 3 and a backscattered electron probe (not shown in the figure).

[0052] The sample stage 1 is disposed at the top of the support frame 3 and is used to fix the sample to be observed;

[0053] The backscattered electron probe is arranged on the fixing seat 2, and is used to receive transmission scattered electrons passing through the sample to be observed;

[0054] The fixing seat 2 is disposed in the supporting frame 3 and connected to the supporting frame 3 , and is used for adjusting the distance between the backscattered electron probe and the sample stage 1 .

[0055] In the embodiment of the present invention, the sample to be observed is a thin sample, usually a Φ3 mm thin sample; the connection method between the fixing seat 2 and the support frame 3 can be a sliding connection, a snap connection, or the like.

[0056] The scanning transmission imaging device in the scanning electron microscope of the present invention uses the backscattered electron probe of the scanning electron microscope as the transmission scattered electron signal detector, and does not need to purchase STEM accessories separately, which can greatly reduce the cost of upgrading the scanning transmission imaging function of the scanning electron microscope. At the same time, the scanning transmission imaging device in the scanning electron microscope of the present invention can significantly reduce the damage of the electron beam to the sample to be observed, and is particularly suitable for the transmission analysis of soft material samples such as organic polymers and biological materials.

[0057] The fixing base 2 of the backscattered electron probe of the present invention is connected to the supporting frame 3, and the distance between the backscattered electron probe and the sample stage 1 can be adjusted as needed, thereby changing the size of the receiving angle of the transmitted scattered electrons, and then realizing the acquisition of high-angle annular dark field images (High-Angle Annular Dark-Field Imaging, HAADF) and low-angle annular dark field images (Low-Angle Annular Dark-Field Imaging, LAADF), so that the obtained image can more accurately reflect the structure and composition information of the sample to be observed.

[0058] Furthermore, the structure of the support frame 3 of the present invention is as follows: Figures 4 to 6 As shown, it includes a frame 31, a sample stage groove 32, a slide rail groove 33 and a first fixing screw 34.

[0059] The sample stage groove 32 is opened at the top of the frame 31, and a transmission through hole 37 is arranged in the sample stage groove 32. The sample to be observed is arranged in the sample stage groove 32;

[0060] The slide rail grooves 33 are disposed on opposite sides of the frame 31;

[0061] The first fixing screw 34 passes through the slide rail slot 33 and is connected to the fixing base 2 , so as to fix the fixing base 2 on the frame 31 .

[0062] In order to ensure that the sample to be observed does not move during the test process, the support frame 3 of the embodiment of the present invention further includes an elastic pressing sheet 35, which is arranged at the top of the frame body 31;

[0063] One end of the elastic pressing piece 35 is fixedly connected to the top of the frame 31, and the other end is disposed on the sample stage 1, and is used to fix the sample stage 1 in the sample stage groove 32. In the embodiment of the present invention, one end of the elastic pressing piece 35 is fixedly connected to the frame 31 using screws.

[0064] In order to ensure the conductivity and stability of the sample stage 1, the embodiment of the present invention further provides a connection hole 36 at the bottom end of the frame 31 for connecting with the sample stage base of the scanning electron microscope.

[0065] In order to facilitate the flexible disassembly and assembly of the sample stage 1, the sample stage 1 is configured as a structure including a support sheet 11 and a cover sheet 12 in the embodiment of the present invention. Figures 7 to 10 shown.

[0066] A sample groove 111 is provided on the first surface of the support sheet 11, and the sample groove 111 is used to carry the sample to be observed;

[0067] The cover sheet 12 is fixed on the support sheet 11, and the first surface of the cover sheet 12 is in contact with the sample to be observed, so as to fix the sample to be observed in the sample groove 111. In the embodiment of the present invention, the first surface of the cover sheet 12 is a plane.

[0068] The sample stage 1 of this structure can realize the replacement of samples outside the electron microscope. After replacement, the sample stage 1 is fixed to the support frame 3, which can greatly shorten the time for replacing samples.

[0069] In order to simultaneously collect the scanning transmission image and the secondary electron image of the sample to be observed, a first funnel-shaped groove 112 is opened on the second surface of the support plate 11 in an embodiment of the present invention. The first funnel-shaped groove 112 is connected to the sample groove 111, and the diameter of the first funnel-shaped groove 112 on the second surface of the support plate 11 is larger than the diameter of the first funnel-shaped groove 112 at the connection with the sample groove 111.

[0070] The embodiment of the present invention further defines a second funnel-shaped groove 121 on the second surface of the cover sheet 12 . The diameter of the second funnel-shaped groove 121 on the second surface of the cover sheet 12 is greater than the diameter of the second funnel-shaped groove 121 on the first surface of the cover sheet 12 .

[0071] The sample stage 1 of the present invention has funnel-shaped grooves on both the upper and lower surfaces, which will not block the transmission electron signal and the secondary electron signal, so the purpose of simultaneously collecting the scanning transmission image and the secondary electron image of the sample to be observed can be achieved.

[0072] In the embodiment of the present invention, the structure of the fixing base 2 is as follows: Fig.11 and Fig.12 As shown, a fixing groove 21 is provided on the fixing seat 2, and the fixing groove 21 is used to fix the backscattered electron probe;

[0073] The bosses 25 on opposite sides of the fixing groove 21 are provided with first threaded holes 22;

[0074] The first fixing screw 34 passes through the slide rail groove 33 and the first threaded hole 22 in sequence to fix the fixing base 2 on the frame 31 .

[0075] A transmission hole 23 is formed on the fixing groove 21 , and the inner hole of the backscattered electron probe matches the transmission hole 23 . Specifically, the inner hole of the backscattered electron probe and the transmission hole 23 have the same size and corresponding position.

[0076] In the embodiment of the present invention, the backscattered electron probe provided by the scanning electron microscope is used as the transmission scattered electron signal detector. The backscattered electron probe is annular, and the diameter of the inner hole is slightly larger than the sample diameter (Φ3mm). Transmitted electrons with a smaller scattering angle can pass through the inner hole, and transmitted electrons with a larger scattering angle will be collected by the annular probe to form an annular dark field image (Annular Dark-Field Imaging, ADF). Since the transmitted electrons with a smaller scattering angle will not directly irradiate the signal detection surface, the problem of signal oversaturation can be avoided.

[0077] In order to further fix the backscattered electron probe, the embodiment of the present invention further has second threaded holes 24 on the bosses 25 on opposite sides of the fixing groove 21;

[0078] The second fixing screw passes through the second threaded hole 24 and is connected to the backscattered electron probe in the fixing groove 21 to fix the backscattered electron probe.

[0079] The fixing seat 2 of the embodiment of the present invention is made of plastic with good insulation properties, so that the backscattered electron probe is insulated from the support frame, avoiding the backscattered electron probe from feeding back a touch signal, causing the scanning electron microscope sample stage base to lock the axis and fail to operate the electron microscope normally.

[0080] The material of the sample stage 1 and the support frame 3 in the embodiment of the present invention is aluminum alloy, which has the advantages of light weight, high strength, good conductivity and low price. The scanning transmission imaging device in the scanning electron microscope prepared using the aluminum alloy has the advantages of light weight, good conductivity, small pressure on the scanning electron microscope sample stage base, long service life and low cost.

[0081] The present invention can achieve the purpose of adjusting the distance between the backscattered electron probe and the sample stage by combining the fixed seat and the support frame, and further realize the function of receiving the transmission scattered electron signal using the backscattered electron probe provided by the scanning electron microscope. The present invention can significantly reduce the damage of the electron beam to the sample to be observed, and is suitable for transmission analysis of samples with poor resistance to electron beam irradiation.

[0082] The present invention takes FEI Quanta 650FEG scanning electron microscope as an example to illustrate the use of the device of the present invention:

[0083] (1) Open the SEM sample chamber, remove the sample stage fixing plate, place the support frame 3 on the sample stage base, align the connection hole 36 at the bottom of the support frame 3 with the threaded hole on the sample stage base, and fix the support frame 3 on the SEM sample stage base with screws passing through the connection hole 36.

[0084] (2) Place the backscattered electron probe of the scanning electron microscope in the fixing groove 21 of the fixing base 2, with the signal detection surface of the backscattered electron probe facing outward and the center hole aligned with the transmission hole 23 of the fixing base 2, and fix it with the second fixing screws in the bosses 25 on both sides of the fixing base 2.

[0085] (3) Place the fixed base 2 with the assembled probe in the support frame 3, with the backscattered electron probe signal detection surface facing upward, the first threaded hole 22 of the fixed base 2 aligned with the slide rail groove 33 of the support frame 3, and use the first fixing screw 34 to pass through the slide rail groove 33 of the support frame 3 and the first threaded hole 22 in the fixed base 2, so as to connect the fixed base 2 and the support frame 3 together.

[0086] (4) Measure the distance between the signal detection surface of the backscattered electron probe and the transmission through hole 37 of the support frame 3, and fix the fixing base 2 to the support frame 3 using the first fixing screw 34 in the slide rail groove 33 of the support frame 3. In this embodiment, the distance between the signal detection surface of the backscattered electron probe and the transmission through hole 37 is 12 mm.

[0087] (5) Place the sample to be observed in the sample groove 111 of the support sheet 11, press it with the first surface of the cover sheet 12, and screw through the through hole of the cover sheet 12 into the threaded hole of the support sheet 11 to clamp the sample to be observed between the support sheet 11 and the cover sheet 12. The sample to be observed in this embodiment is a Φ3 mm thin sample.

[0088] (6) Place the assembled sample stage 1 in the sample stage groove 32 at the top of the support frame 3 , and use the elastic pressing piece 35 at the top of the support frame 3 to fix the sample stage 1 in the sample stage groove 32 .

[0089] (7) Close the SEM sample chamber and evacuate the chamber before observation. During the observation process, the scanning transmission annular dark field (STEM-ADF) image and the secondary electron (SE) image can be displayed simultaneously. The STEM-ADF image can be achieved by simply selecting the BSED probe in the SEM operation interface.

[0090] (8) After the test is completed, deflate the SEM sample chamber and open the sample chamber to replace the sample or remove the scanning transmission imaging device.

[0091] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A scanning transmission imaging device in a scanning electron microscope, characterized in that: It includes a sample stage, a fixing seat, a supporting frame and a backscattered electron probe; The sample stage is arranged at the top of the support frame and is used to fix the sample to be observed; The backscattered electron probe is arranged on the fixing seat and is used to receive transmission scattered electrons passing through the sample to be observed; The fixing seat is arranged in the supporting frame and connected to the supporting frame, and is used to adjust the distance between the backscattered electron probe and the sample stage; The sample stage comprises a support sheet and a cover sheet; A sample groove is provided on the first surface of the support sheet, and the sample groove is used to carry the sample to be observed; The cover sheet is fixed on the support sheet, and the first surface of the cover sheet is in contact with the sample to be observed, so as to fix the sample to be observed in the sample groove; A first funnel-shaped groove is formed on the second surface of the support sheet, the first funnel-shaped groove is connected to the sample groove, and the diameter of the first funnel-shaped groove on the second surface of the support sheet is larger than the diameter of the first funnel-shaped groove at the connection with the sample groove; A second funnel-shaped groove is formed on the second surface of the cover sheet, and a diameter of the second funnel-shaped groove on the second surface of the cover sheet is greater than a diameter of the second funnel-shaped groove on the first surface of the cover sheet.

2. The scanning transmission imaging device in a scanning electron microscope according to claim 1, characterized in that: The support frame includes a frame body, a sample stage groove, a slide rail groove and a first fixing screw; The sample stage groove is opened at the top of the frame body, a transmission through hole is arranged in the sample stage groove, and the sample stage is arranged in the sample stage groove; The slide rail grooves are arranged on opposite sides of the frame; The first fixing screw passes through the slide rail slot and is connected to the fixing base, so as to fix the fixing base on the frame.

3. The scanning transmission imaging device in a scanning electron microscope according to claim 2, characterized in that: The support frame further comprises an elastic pressing sheet, and the elastic pressing sheet is arranged at the top end of the frame body; One end of the elastic pressing sheet is fixedly connected to the top of the frame, and the other end is arranged on the sample stage, and is used to fix the sample stage in the groove of the sample stage; The bottom end of the frame is provided with a connection hole connected with the sample stage base of the scanning electron microscope.

4. The scanning transmission imaging device in a scanning electron microscope according to claim 2, characterized in that: The fixing seat is provided with a fixing groove, and the fixing groove is used to fix the backscattered electron probe; The bosses on the opposite sides of the fixing groove are provided with first threaded holes; The first fixing screw passes through the slide rail groove and the first threaded hole in sequence to fix the fixing seat on the frame.

5. The scanning transmission imaging device in a scanning electron microscope according to claim 4, characterized in that: A transmission hole is provided on the fixing groove, and the inner hole of the backscattered electron probe matches the transmission hole.

6. The scanning transmission imaging device in a scanning electron microscope according to claim 4, characterized in that: Second threaded holes are also provided on the bosses on opposite sides of the fixing groove; The second fixing screw passes through the second threaded hole and is connected to the backscattered electron probe in the fixing groove, so as to fix the backscattered electron probe.

7. The scanning transmission imaging device in a scanning electron microscope according to claim 1, characterized in that: The material of the fixing seat is plastic; The sample stage and the support frame are made of aluminum alloy.

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