Electron beam blocker, electrostatic lens and scanning electron microscope

Abstract

The present invention relates to an electron beam blocker, an electrostatic lens and a scanning electron microscope. The electron beam blocker comprises: a substrate having a central through hole, wherein the substrate is divided into a left lobe electrode and a right lobe electrode along the axis of the central through hole, and the left lobe electrode and the right lobe electrode are isolated from each other by an insulating layer; the left lobe electrode and the right lobe electrode are used to apply different voltages to generate a transverse deflection electric field; a protrusion extending outward along the path of the electron beam is provided on one side of the substrate close to the central through hole, so as to increase the longitudinal coverage of the transverse deflection electric field area and prolong the time the electron beam is subjected to the transverse deflection electric field; the electron beam blocker integrates the electrostatic lens pole piece and the electron beam blocking function, reduces the number of components and power supplies, reduces the size of the device, is conducive to device integration, can also reduce electromagnetic interference, and improve imaging quality. The design of the protrusion can prolong the time the electron beam is subjected to the transverse deflection electric field, and further improve the accuracy of electron beam control.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic optical instruments, and in particular to an electron beam blocker, an electrostatic lens and a scanning electron microscope. Background Art

[0002] A scanning electron microscope (SEM) is a high-resolution microscope that uses a focused electron beam to scan a sample's surface, detecting the signals generated by its interaction with the sample to obtain information about the sample's surface morphology and composition. In an SEM, the electrostatic lens and beam blanker are two key components.

[0003] An electrostatic lens is a lens system used to focus the electron beam in a SEM. It typically consists of several layers of annular electrodes. Different voltages are applied to different layers to create an electrostatic field, thereby controlling the focus of the electron beam. The design principle of an electrostatic lens is based on the electrostatic force. By rationally designing the electrode structure and voltage distribution, the electron beam can be focused or defocused. Compared to traditional magnetic lenses, electrostatic lenses require less space and have a higher modulation bandwidth. These unique advantages make them an indispensable component in SEMs.

[0004] The blanker is also a key component in the SEM, used to control the on and off of the electron beam. It is usually installed in the path of the electron beam and blocks the electron beam by applying an electric field, thereby achieving precise scanning of the sample. The main function of the blanker is to turn it off when the electron beam is not needed to irradiate the sample, such as when the line scan returns, to avoid unnecessary electron beam exposure. This is very important for improving image quality and protecting the sample from excessive radiation. Compared with mechanical switches, using electric fields to adjust the on and off of the electron beam has the advantages of fast modulation speed and simple structure.

[0005] In SEM, electrostatic lenses and blankers work together to ensure that the electron beam can accurately scan the sample surface and be turned on and off when needed. This precise control is essential for obtaining high-quality SEM images. The conventional blanker structure is two parallel plate electrodes, such as Figure 4 As shown in Figure 1, a voltage difference of several hundred volts exists between the left pole piece 601 and the right pole piece 602, generating a transverse electric field that deflects the passing electron beam. The electrostatic lens and blanker, as two separate components, occupy a large volume and weight, hindering device integration. Using separate power supplies can introduce electromagnetic noise that interferes with imaging quality. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides an electron beam blocker, an electrostatic lens and a scanning electron microscope, aiming to solve the problem that the existing electrostatic lens and blanker are two components, occupying a large volume and weight, which is not conducive to equipment integration, and using separate power supplies may introduce electromagnetic noise that interferes with imaging quality.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solutions: an electron beam blocker, comprising a substrate having a central through hole, wherein the substrate is divided into a left lobe electrode and a right lobe electrode along the axis of the central through hole, and the left lobe electrode and the right lobe electrode are isolated from each other by an insulating layer; the left lobe electrode and the right lobe electrode are used to apply different voltages to generate a transverse deflection electric field, and a protrusion extending outward along the path of the electron beam is provided on one side of the substrate close to the central through hole to increase the longitudinal coverage of the transverse deflection electric field area and prolong the time that the electron beam is subjected to the transverse deflection electric field.

[0008] Furthermore, the protrusion is an annular structure or a flat plate structure provided on the base and extending upward.

[0009] An electrostatic lens has an electron beam through hole for an electron beam to pass through, comprising: an upper pole piece, an electron beam blocker and a lower pole piece arranged in sequence along the path of the electron beam, wherein the electron beam through holes of the upper pole piece and the lower pole piece are coaxially arranged with the central through hole of the electron beam blocker.

[0010] Furthermore, a sleeve structure overlapping with the central through hole is extended from a side of the lower pole piece away from the electron beam blocker.

[0011] Furthermore, an aperture is provided on a side of the sleeve structure away from the lower pole piece, and an aperture hole is opened on the aperture, and the aperture hole is used to pass the undeflected electron beam and block the deflected electron beam.

[0012] Furthermore, insulating components are provided between the electron beam blocker and the upper pole piece, and between the electron beam blocker and the lower pole piece, and the electron beam blocker is fixed and electrically insulated from the upper pole piece and the lower pole piece through the insulating components.

[0013] Furthermore, the insulating component is a ceramic ball, and ceramic ball fixing holes are respectively provided on the lower side of the upper pole piece, the upper and lower sides of the electron beam blocker, and the upper side of the lower pole piece, wherein: the ceramic ball fixing hole of the upper pole piece is coaxially aligned with the ceramic ball fixing hole on the upper side of the electron beam blocker; the ceramic ball fixing hole of the lower pole piece is coaxially aligned with the ceramic ball fixing hole on the lower side of the electron beam blocker; and the ceramic balls are embedded in the corresponding ceramic ball fixing holes.

[0014] Furthermore, a connecting piece is included, and the upper pole piece and the lower pole piece are fixed by the connecting piece.

[0015] Furthermore, the connecting member is a conductive screw, which mechanically fixes the upper electrode and the lower electrode and maintains equipotential electrical conduction.

[0016] Furthermore, the connecting piece is an insulating screw to ensure that all the electrons received by the lower electrode are conducted by wires to an external picoammeter for detection.

[0017] A scanning electron microscope comprises the electrostatic lens described above.

[0018] Furthermore, it also includes an extraction stage, a condenser array and an objective lens system, and the extraction stage, the electrostatic lens, the condenser array and the objective lens system are arranged in sequence on the path of the electron beam.

[0019] Furthermore, it also includes an extraction stage, an anode, a condenser array and an objective lens system, and the extraction stage, the anode, the condenser array, the electrostatic lens and the objective lens system are arranged in sequence on the path of the electron beam.

[0020] The electron beam blocker, electrostatic lens and scanning electron microscope described in the present invention have the following beneficial effects:

[0021] 1. The electron beam blocker provided in the present application includes a substrate with a central through hole, and the substrate is divided into a left lobe electrode and a right lobe electrode along the axis of the central through hole. The lobes are insulated, and the two lobe electrodes are used to apply different voltages. This design can simultaneously realize the functions of an electrostatic lens and an electron beam blocker, reduce the number of components and power supplies, reduce the size of the equipment, facilitate equipment integration, reduce electromagnetic interference, and improve imaging quality.

[0022] 2. A protrusion extending outward along the electron beam path is located on one side of the electron beam blocker's base, near the central through-hole. This design increases the longitudinal coverage of the transverse deflection electric field and prolongs the time the electron beam is exposed to the transverse deflection field. This characteristic increases the deflection distance of the electron beam at the same deflection voltage, or reduces the voltage by half at the same deflection distance. Furthermore, the protrusion partially shields the external electric field, ensuring that the electron beam is only affected by the transverse deflection field, further improving the precision of electron beam control. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the three-dimensional structure of an electrostatic lens according to an embodiment of the present invention;

[0024] Figure 2 1 is a schematic diagram of the planar structure of an electrostatic lens according to an embodiment of the present invention;

[0025] Figure 3This is a schematic diagram of the relationship between the emission angle of the electron beam passing through the electrostatic lens and the voltage of the electron beam blocker;

[0026] Figure 4 2. It is a schematic diagram of a traditional BLANKER structure according to an embodiment of the present invention;

[0027] Figure 5 is a schematic structural diagram of an electron beam blocker according to an embodiment of the present invention;

[0028] Figure 6 1 is a schematic diagram of an improved structure of an electron beam blocker according to an embodiment of the present invention;

[0029] Figure 7 1 is a schematic diagram of the lower pole piece structure of an embodiment of the present invention;

[0030] Figure 8 Schematic diagram of a scanning electron microscope with different electrostatic lens layouts.

[0031] Explanation of the reference numerals: 1. Upper pole piece; 101. Electron beam through hole; 102. First through hole; 103. Ceramic ball fixing hole of upper plate; 2. Electron beam blocker; 201. Left lobe electrode; 202. Right lobe electrode; 203. Insulation pad; 204. High voltage interface; 205. Second through hole; 206. Ceramic ball fixing hole of electron beam blocker; 207. Ring structure; 3. Lower pole piece; 301. Assembly hole; 302. Sleeve structure; 303. Aperture hole; 4. Ceramic ball; 701. Electron gun; 702. Aperture; 703. Condenser array; 704. Detector; 705. Objective system; 706. Sample; 707. Anode; 708. Extraction stage. DETAILED DESCRIPTION

[0032] Typical embodiments embodying the features and advantages of the present invention are described in detail in the following description. It should be understood that the present invention is capable of various variations in different embodiments without departing from the scope of the present invention, and that the descriptions and illustrations herein are intended to be illustrative rather than limiting.

[0033] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0034] In order to further illustrate the principle and structure of the present invention, preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] This invention relates to an electron beam blocker, an electrostatic lens, and a scanning electron microscope (SEM). These devices aim to address the bulk and weight of existing SEMs, as well as electromagnetic noise that interferes with imaging quality, caused by the separate placement of the electrostatic lens and beam blocker. Through an innovative structural design, the electrostatic lens and blanker functions are integrated into one, enabling electron beam focusing and on / off control, effectively improving the performance of the SEM.

[0036] like Figure 5-Figure 6 As shown, an embodiment of the present invention provides an electron beam blocker. This embodiment employs an innovative split-electrode design. Its structure includes an annular substrate (intermediate electrode) with a central through-hole at its center for the electron beam to pass through. The substrate is precisely divided along the axis of the central through-hole into a left-lobe electrode 201 and a right-lobe electrode 202. The two electrodes are spatially symmetrically distributed and separated by an insulating pad 203. The left-lobe electrode 201 and the right-lobe electrode 202 are each equipped with an independent high-voltage interface 204. This design enables the electron beam blocker 2 to generate a transverse deflection electric field.

[0037] For further reference, see Figure 5-Figure 6 As shown, a protrusion extending outward along the path of the electron beam is provided on one side of the substrate close to the central through hole to increase the longitudinal coverage of the transverse deflection electric field area and prolong the time the electron beam is subjected to the transverse deflection electric field.

[0038] Based on the above structure, the embodiments of the present invention incorporate an electric field enhancement design into the central through-hole of the electron beam blocker 2. By modifying the local structure of the electron beam blocker 2 (i.e., the protrusion), the electrostatic lens's control over the electron beam is enhanced, thereby enhancing the overall performance of the scanning electron microscope. This structural design, while focusing on enhancing the electric field effect, specifically optimizes the electron beam's behavior in the transverse deflection electric field without changing the core architecture of the entire device, achieving more precise electron beam control and better imaging quality.

[0039] Specifically, a side of the substrate of the electron beam blocker 2 near the central through hole is provided with an annular structure 207 or a flat plate structure extending upward or downward. The height of the structure is set within the range of 0.3-2.8mm, preferably 2mm. The advantage of such a design is to increase the longitudinal coverage of the transverse deflection electric field region and extend the time the electron beam is subjected to the field in the transverse deflection electric field, which means that the same deflection position can be reached using a smaller deflection voltage. If the speed of the electron beam is constant, doubling the action time of the electron beam and the transverse electric field can halve the deflection distance of the electron beam under the same deflection voltage, or halve the voltage under the same deflection distance. In addition, the structure can also shield a portion of the external electric field to ensure that the electron beam is only subjected to the effect of the transverse deflection electric field, further improving the accuracy of electron beam manipulation.

[0040] like Figures 1-6 、 Figure 8 As shown, an embodiment of the present invention provides an electrostatic lens having an electron beam through hole 101 for an electron beam to pass through, and the electrostatic lens includes an upper pole piece 1, an electron beam blocker 2, and a lower pole piece 3 arranged in sequence along the electron beam path. The upper pole piece 1 is close to the electron gun 701 end, and the lower pole piece 3 is close to the sample 706 end. The electron beam through holes 101 of the upper pole piece 1 and the lower pole piece 3 are coaxially arranged with the central through hole of the electron beam blocker 2 to ensure that the electron beam can pass through each pole piece smoothly, providing a stable channel for the focusing and transmission of the electron beam. The voltage of the electron beam blocker 2 can be adjusted independently of the upper pole piece 1 and the lower pole piece 3. This independent adjustment feature is the key to achieving precise control of the electron beam.

[0041] The electron beam blocker 2 of an embodiment of the present invention is integrated into the electrostatic lens and can serve as the intermediate pole piece of the electrostatic lens, simultaneously realizing the functions of the electrostatic lens and the blanker. This reduces the number of components, significantly reduces the size of the scanning electron microscope equipment, reduces the weight, and is conducive to the integrated design and application of the equipment. In terms of imaging quality, since the use of separate power supplies is reduced, the interference of electromagnetic noise on imaging is effectively reduced, and the image quality obtained by the scanning electron microscope is improved. The special structural design of the electron beam blocker 2 achieves more precise control of the electron beam, while protecting the sample 706 from excessive radiation, and further improving the accuracy and clarity of the imaging.

[0042] In actual application scenarios, for the electrostatic lens involved in the present invention, the high voltage applied by the upper pole piece 1 and the lower pole piece 3 is usually set at about 10 kV.

[0043] In this electrostatic lens structure, the electron beam blocker 2 plays a key role. Its voltage can be adjusted independently of the upper and lower pole pieces 1 and 3, with a specific adjustment range of 3-12 kV. By adjusting the voltage of the electron beam blocker 2, the electron beam intersection point can be adjusted. For example, when electron beam irradiation of the sample 706 is not required (such as during line scan return), the voltage of the left or right lobe electrode 201 or 202 of the electron beam blocker 2 is changed to deflect the electron beam, thereby blocking the electron beam from irradiating the sample 706 and preventing unnecessary electron beam exposure.

[0044] Compared with the traditional magnetic lens, the electrostatic lens in the present invention has significant advantages. On the one hand, its modulation speed can reach the MHz level, which is a significant improvement compared with the magnetic lens; on the other hand, its structural design is more compact and occupies less space. Figure 3 It can be observed intuitively that when the voltage of the electron beam blocker 2 varies between 10V and 15000V, the left lobe electrode 201 and the right lobe electrode 202 are at equal pressure. As the applied voltage changes, the electron beam emission angle shows a regular change, gradually decreasing from the initial 10mrad to 0.7mrad, and then increasing to 2mrad. This characteristic provides strong support for the precise control of the electron beam.

[0045] Further, if Figure 7 As shown, a sleeve structure 302 is provided on the side of the lower pole piece 3 that extends away from the electron beam blocker 2 and overlaps the central through hole. This sleeve structure 302 acts as a capture cage for the blanker function in the entire system. Preferably, the central through hole and sleeve structure 302 are coaxially arranged to enhance the sleeve structure 302's ability to capture electrons.

[0046] When the electrostatic lens performs the blanker function, the voltages of the left and right lobe electrodes 201, 202 of the electron beam blanker 2 change, creating a voltage difference between the left and right lobe electrodes 201, 202, and causing the electron beam to deflect. The deflected electrons then collide with the sleeve structure 302 of the lower pole piece 3. The sleeve structure 302 of the lower pole piece 3 effectively confines as many of the deflected electrons as possible, as well as the secondary electrons generated by impacting the sleeve structure 302 wall, within the sleeve, preventing these electrons from escaping into the external space. This characteristic is crucial for realizing the Faraday cup function and accurately measuring current.

[0047] In actual operation, the left and right lobe electrodes 201, 202 of the electron beam blanker 2 are initially synchronously adjusted to a specific voltage, for example, 8000V, and then fixed. When the blanker function is required, only the voltage of the left lobe electrode 201 or the right lobe electrode 202 of the electron beam blanker 2 is changed to create a 500V voltage difference between the left lobe electrode 201 and the other lobe.

[0048] Taking the deflection voltage of the electron beam blocker 2 as 500V as an example, in this case, the diameter of the center hole of the electron beam blocker 2 is set to be about 5mm. According to the electric field strength calculation formula, the central transverse electric field strength can be obtained to be about E = 10 5 V / m. Based on the force formula of electrons in an electric field, F = Eq (where q is the electron charge) and Newton's second law, F = ma (m is the electron mass), it can be deduced that the lateral acceleration of the electron beam is a = E*q / m. It is estimated that the lateral acceleration of the electron is about 2×10 16 m / s 2 Considering the action time of the transverse electric field on the electron beam, the thickness I of the electron beam blocker 2 is set to 3 mm, the electron velocity is v, and according to the formula t = I / v, the action time of the transverse electric field can be calculated to be approximately t = 10 - 10 s. Under the action of this voltage difference, the electron beam will produce a certain deflection. Calculations show that the deflection distance is approximately 0.1 mm, corresponding to a deflection angle of approximately 30 mrad. The distance from the electron beam leaving the electron beam blocker 2 to reaching the bottom of the lower pole piece 3 is approximately 20 mm, corresponding to a deflection distance of approximately 1 mm. At this point, the electron beam can just hit the aperture 702 located below the sleeve structure 302 (described below as aperture 702), achieving maximum shielding of the deflected electron spot.

[0049] Specifically, when the aperture of the sleeve structure 302 is 5 mm, an aperture 702 is provided below the sleeve structure 302, and the aperture 702 has an aperture hole 303 with an aperture of about 0.5 mm (refer to Figure 7 and 8 The aperture 303 has an aperture diameter smaller than the central through hole diameter of the electron beam blocker 2. The aperture 303 has a dual function: on the one hand, it allows electrons to pass smoothly when the electron beam is not deflected; on the other hand, when a transverse deflection electric field exists, it can block the deflected electron spot to the greatest extent possible.

[0050] Furthermore, some ventilation holes can be appropriately opened in the non-aperture area of the aperture to reduce the vacuum difference between the upper and lower chambers.

[0051] Furthermore, in the electrostatic lens structure of the present invention, to ensure that the electron beam blocker 2 can perform voltage regulation independently of the upper pole piece 1 and the lower pole piece 3, an insulating component is provided between the electron beam blocker 2 and the upper pole piece 1 and the lower pole piece 3. This insulating component not only provides electrical insulation, preventing current from arbitrarily conducting between the different pole pieces and affecting the normal operation of the electrostatic lens, but also fulfills the important task of fixing the electron beam blocker 2, ensuring the stability of the entire electrostatic lens structure, while also improving the integration of the device.

[0052] The present invention uses ceramic balls 4 as insulating components because they have good insulating properties and can effectively meet the requirements of electrical insulation. At the same time, they have stable mechanical properties and can play an important role in maintaining structural stability.

[0053] Specifically, holes for securing the ceramic balls 4 are provided on the underside of the upper pole piece 1, on the upper and lower sides of the electron beam blocker 2, and on the upper side of the lower pole piece 3. The ceramic ball 4 securing hole 103 of the upper pole piece 1 is coaxially aligned with the ceramic ball 4 securing hole 206 on the upper side of the electron beam blocker 2. The ceramic ball 4 securing hole (not shown) of the lower pole piece 3 is coaxially aligned with the ceramic ball 4 securing hole 206 on the lower side of the electron beam blocker 2. This coaxial alignment design allows the ceramic balls 4 to be precisely embedded in their corresponding ceramic ball 4 securing holes, thereby ensuring that the relative positions of the pole pieces are accurate and that the performance of the electrostatic lens is not affected.

[0054] To further ensure structural stability and reliability, the number of holes for securing the ceramic balls 4 is set to three or more. Multiple ceramic balls 4 are evenly distributed between the pole pieces, allowing them to more evenly withstand the weight of the electron beam blocker 2 and forces acting from various directions, effectively enhancing the stability of the entire structure. In practical applications, this structural design can effectively reduce pole piece displacement caused by external vibration or other factors, ensuring that the electrostatic lens remains in good working condition during extended use, thereby ensuring that the scanning electron microscope can stably and accurately control the electron beam and achieve high-quality imaging results.

[0055] Furthermore, in the electrostatic lens structure of the present invention, when the lower pole piece is not used as a Faraday cup, a connector is provided to achieve a specific electrical connection and mechanical fixation between the upper pole piece 1 and the lower pole piece 3. This connector plays a crucial role in the entire structure, ensuring that the upper pole piece 1 and the lower pole piece 3 are not only mechanically firmly connected, but also ensuring the stable operation of the overall electrostatic lens function.

[0056] Specifically, a first through-hole 102 for screws is provided on the upper pole piece 1, a second through-hole 205 for screws is provided on the electron beam blocker 2, and corresponding screw fixing holes (not shown) are provided on the lower pole piece 3. The conductive connector used in the present invention is a conductive screw, which not only provides mechanical fixing but also meets the requirements of electrical continuity and maintains electrical equipotentiality.

[0057] During the actual assembly process, the conductive screw passes through the first through-hole 102 of the upper pole piece 1, the second through-hole 205 on the electron beam blocker 2, and then closely mates with the screw fixing hole of the lower pole piece 3, thereby firmly mechanically fixing the upper pole piece 1 and the lower pole piece 3 together. The conductive screw only passes through the second through-hole 205 and does not come into contact with the electron beam blocker 2. This mechanical fixing method ensures the relative stability of the upper pole piece 1 and the lower pole piece 3 in space, effectively preventing the position of the pole pieces from changing due to factors such as vibration and displacement during operation of the equipment, thereby affecting the focusing and control effect of the electrostatic lens on the electron beam.

[0058] At the same time, the conductive properties of the conductive screws ensure electrical continuity between the upper and lower electrodes 1 and 3, maintaining the same potential. This equipotentiality helps form a specific electrostatic field distribution. This, combined with the independently adjustable voltage of the electron beam blocker 2, enables precise focusing and deflection of the electron beam. This meticulously designed conductive connector ensures the dual stability of the electrostatic lens in both mechanical and electrical performance, significantly enhancing the imaging quality and operating efficiency of the scanning electron microscope.

[0059] When the lower electrode is used as a Faraday cup and the current passing through is measured using the blanker function, the wire screws of the upper and lower electrodes need to be replaced with insulating screws to ensure that all electrons received by the lower electrode are conducted by the wires to the external picoammeter for detection and cannot be transmitted to the upper electrode.

[0060] Furthermore, a plurality of assembly holes 301 are provided on the lower pole piece 3 , and the assembly holes 301 are for fixing screws (not shown) to pass through. With the action of the fixing screws, the lower pole piece 3 is fixedly mounted on the scanning electron microscope.

[0061] In this embodiment, the electrostatic lens is fixedly mounted on the scanning electron microscope through the assembly hole, thereby ensuring the stability and detachability of the electrostatic lens.

[0062] The present invention also provides a scanning electron microscope, which includes the electrostatic lens described above. By integrating the electron beam blocker into the electrostatic lens, the space occupied by the scanning electron microscope can be reduced, the device can be miniaturized, and the problems of low internal component integration and electromagnetic noise can be solved.

[0063] Furthermore, the scanning electron microscope further includes an electron gun 701 , which is used to generate an electron beam, and the electrostatic lens is used to perform multi-stage focusing control on the electron beam generated by the electron gun 701 .

[0064] In an optional embodiment, the positional relationship of each component in the scanning electron microscope is set according to different requirements, and the specific reference is Figure 8 As shown on the left, the SEM also includes an extraction stage 708. The extraction stage 708, electrostatic lens, condenser array 703, and objective lens system 705 are sequentially arranged in the electron beam path. The upper electrode 1 of the electrostatic lens can serve as an anode. The extraction stage 708 and the upper electrode 1 work together to realize the function of the electrostatic lens. The two work synergistically to converge the electron beam. This design reduces the number of anode components, reduces the size and weight of the SEM equipment, and facilitates device integration.

[0065] In actual application scenarios, for the scanning electron microscope involved in the present invention, the high voltage applied to the upper pole piece 1 described above is usually set at about 10kV. After the electron beam is emitted from the electron gun 701, it passes through the extraction stage. At this time, the energy of the electron beam is generally in the range of 1-5kV. The distance between the extraction stage and the upper pole piece 1 is approximately 10mm. Within this range, there is an electric potential gradient (acceleration field) with an intensity of about 6kV / cm. Based on the action of this acceleration field, the electron beam will continue to accelerate until it reaches an energy state of 10kV and successfully reaches the upper pole piece 1.

[0066] In another optional embodiment, the scanning electron microscope further includes an extraction stage 708 and an anode 707, such as Figure 8 As shown on the right, the extraction stage 708, anode 707, condenser lens array 703, electrostatic lens, and objective lens system 705 are sequentially arranged in the electron beam path. In this case, the electrostatic lens can be at the same potential as the lens barrel, eliminating the need for a higher voltage upper electrode as an anode. By providing a separate anode, the voltage required by the objective lens system is low. This low voltage results in low excitation of the objective lens, preventing magnetic saturation under high excitation.

[0067] In summary, by setting the electrostatic lens at different positions of the scanning electron microscope, the voltage excitation of the electrostatic lens at different positions can be adjusted to change the electron optical path, reduce the aberration and improve the resolution.

[0068] The condenser lens array 703 includes a first condenser lens and a second condenser lens sequentially arranged along the beam direction.

[0069] The scanning electron microscope of the present invention further includes a detector 704 , which is disposed between the condenser lens array 703 and the objective lens system 705 .

[0070] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An electrostatic lens comprising an electron beam blocker, wherein the electrostatic lens has an electron beam through hole for the electron beam to pass through, characterized in that: include: An upper pole piece, the electron beam blocker and a lower pole piece are sequentially arranged along the path of the electron beam, wherein the electron beam through holes of the upper pole piece and the lower pole piece are coaxially arranged with the central through hole of the electron beam blocker; The electron beam blocker comprises a substrate having a central through hole, the substrate being divided into a left lobe electrode and a right lobe electrode along the axis of the central through hole, the left lobe electrode and the right lobe electrode being isolated from each other by an insulating layer; the voltages of the left lobe electrode and the right lobe electrode can be independently adjusted, and the left lobe electrode and the right lobe electrode are used to apply different voltages to generate a transverse deflection electric field; A protrusion extending outward along the path of the electron beam is provided on one side of the base body close to the central through hole to increase the longitudinal coverage of the transverse deflection electric field area and prolong the time the electron beam is subjected to the transverse deflection electric field.

2. The electrostatic lens according to claim 1, wherein The protrusion is an annular structure or a flat plate structure provided on the base and extending upward.

3. The electrostatic lens according to claim 1, wherein A sleeve structure overlapping with the central through hole is extended from one side of the lower pole piece away from the electron beam blocker.

4. The electrostatic lens according to claim 3, characterized in that A diaphragm is provided on a side of the sleeve structure away from the lower pole piece. A diaphragm hole is opened on the diaphragm. The diaphragm hole is used to pass the undeflected electron beam and block the deflected electron beam.

5. The electrostatic lens according to claim 4, characterized in that Insulating components are provided between the electron beam blocker and the upper pole piece, and between the electron beam blocker and the lower pole piece. The electron beam blocker is fixed to and electrically insulated from the upper pole piece and the lower pole piece through the insulating components.

6. The electrostatic lens according to claim 5, characterized in that The insulating component is a ceramic ball, and ceramic ball fixing holes are respectively provided on the lower side of the upper pole piece, the upper and lower sides of the electron beam blocker, and the upper side of the lower pole piece, wherein: the ceramic ball fixing hole of the upper pole piece is coaxially aligned with the ceramic ball fixing hole on the upper side of the electron beam blocker; the ceramic ball fixing hole of the lower pole piece is coaxially aligned with the ceramic ball fixing hole on the lower side of the electron beam blocker; and the ceramic balls are embedded in the corresponding ceramic ball fixing holes.

7. The electrostatic lens according to claim 1, wherein It also includes a connecting piece, and the upper pole piece and the lower pole piece are fixed by the connecting piece.

8. The electrostatic lens according to claim 7, wherein: The connecting piece is a conductive screw, which mechanically fixes the upper electrode and the lower electrode and maintains equipotential electrical conduction.

9. The electrostatic lens according to claim 7, wherein: The connecting piece is an insulating screw to ensure that all the electrons received by the lower pole piece are led out by the wire to the external picoammeter for detection.

10. A scanning electron microscope, characterized in that The scanning electron microscope comprises the electrostatic lens according to any one of claims 3 to 9.

11. The scanning electron microscope according to claim 10, characterized in that It also includes an extraction stage, a condenser lens array and an objective lens system. The extraction stage, the electrostatic lens, the condenser lens array and the objective lens system are arranged in sequence on the path of the electron beam.

12. The scanning electron microscope according to claim 10, characterized in that It also includes an extraction stage, an anode, a condenser array and an objective lens system. The extraction stage, the anode, the condenser array, the electrostatic lens and the objective lens system are arranged in sequence on the path of the electron beam.

Images