Electron beam blocker, electrostatic lens and scanning electron microscope

Abstract

The invention relates to an electron beam blocker, an electrostatic lens and a scanning electron microscop.The electron beam blocker comprises a base body with a center through hole, the base body is divided into a left lobe electrode and a right lobe electrode along the axis of the center through hole, and the left lobe electrode and the right lobe electrode are isolated through an insulating layer; the left-lobe electrode and the right-lobe electrode are used for applying different voltages to generate a transverse deflection electric field, and one side, close to the central through hole, of the base body is provided with a bulge extending outwards along the path of an electron beam, so that the longitudinal coverage range of a transverse deflection electric field area is increased, and the field receiving time of the electron beam in the transverse deflection electric field is prolonged; the electron beam blocker integrates the electrostatic lens pole piece and the electron beam blocking function, the number of components and power sources is reduced, the equipment size is reduced, equipment integration is facilitated, electromagnetic interference can be reduced, the imaging quality is improved, the field receiving time of electron beams in a transverse deflection electric field can be prolonged through the design of the protrusions, and the electron beam control precision is further improved.

Description

Technical Field

[0001] The 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] Scanning electron microscope (SEM) is a high-resolution microscope that uses a focused electron beam to scan the sample surface and obtain information about the sample's surface morphology and composition by detecting the signal generated by the interaction with the sample. In SEM, the electrostatic lens and the electron beam blanker are two important components.

[0003] The electrostatic lens is a lens system used to focus the electron beam in the SEM. It is usually composed of several layers of annular electrodes. Different layers of electrodes form an electrostatic field by applying different voltages to control the focus of the electron beam. The design principle of the electrostatic lens is based on the action of electrostatic force. By rationally designing the electrode structure and voltage distribution, the electron beam can be focused and defocused. Compared with traditional magnetic lenses, electrostatic lenses require less space and have a higher modulation bandwidth. They have unique advantages and are an indispensable component in scanning electron microscopes.

[0004] Blanker is also a key component in SEM, used to control the on and off of the electron beam. It is usually installed on the path of the electron beam and blocks the electron beam by applying an electric field, thereby achieving accurate scanning of the sample. The main function of 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, which 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 turn 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. There is a voltage difference of several hundred V between the left pole piece 601 and the right pole piece 602, which generates a transverse electric field to deflect the electron beam passing through. As two components, the electrostatic lens and the blanker occupy a large volume and weight, which is not conducive to device integration. Using power supplies separately at the same time may introduce electromagnetic noise that interferes with the imaging quality. Summary of the invention

[0006] In view of the shortcomings of the prior art, 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 purpose, the present invention adopts the following technical scheme: an electron beam blocker, comprising a substrate with a central through hole, the substrate is 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 are isolated 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 that is arranged on the base and extends upward.

[0009] An electrostatic lens has an electron beam through hole for electron beams 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 a central through hole of the electron beam blocker.

[0010] Furthermore, 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.

[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 by 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 ball is embedded in the corresponding ceramic ball fixing hole.

[0014] Furthermore, it also includes a connecting piece, 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 sheet and the lower electrode sheet and maintains equipotential electrical conduction.

[0016] Furthermore, the connecting piece is an insulating screw to ensure that all the electrons received by the lower pole piece 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: 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 device, facilitate device integration, and can also reduce electromagnetic interference and improve imaging quality.

[0021] 2. A protrusion extending outward along the path of the electron beam is provided on one side of the electron beam blocker substrate close to the central through hole. This design increases the longitudinal coverage of the transverse deflection electric field area and prolongs the time the electron beam is affected by the transverse deflection electric field. Based on this feature, it can increase the deflection distance of the electron beam under the same deflection voltage, or halve the voltage under the same deflection distance. In addition, the protrusion can also shield part of the external electric field to ensure that the electron beam is only affected by the transverse deflection electric field, further improving the accuracy of electron beam control. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of the three-dimensional structure of an electrostatic lens according to an embodiment of the present invention; Figure 2 is a schematic diagram of the planar structure of an electrostatic lens according to an embodiment of the present invention; Figure 3 It 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; Figure 4 is a schematic diagram of a traditional BLANKER structure of an embodiment of the present invention; Figure 5 is a schematic structural diagram of an electron beam blocker according to an embodiment of the present invention; Figure 6 is a schematic diagram of an improved structure of an electron beam blocker according to an embodiment of the present invention; Figure 7 is a schematic diagram of the structure of the lower pole piece of an embodiment of the present invention; Figure 8 Schematic diagram of a scanning electron microscope with different electrostatic lens layouts.

[0023] 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. insulating pad; 204. high voltage interface; 205. second through hole; 206. ceramic ball fixing hole of electron beam blocker; 207. annular 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 lens system; 706. sample; 707. anode; 708. extraction stage. DETAILED DESCRIPTION

[0024] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations therein are essentially used for illustration purposes rather than for limiting the present invention.

[0025] 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 positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying 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 a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0026] In order to further illustrate the principle and structure of the present invention, preferred embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0027] The present invention relates to an electron beam blanker, an electrostatic lens and a scanning electron microscope, aiming to solve the problems of large volume, heavy weight and electromagnetic noise interference with imaging quality caused by the separate arrangement of the electrostatic lens and the electron beam blanker in the existing scanning electron microscope. Through innovative structural design, the electrostatic lens and the blanker functions are integrated into one, the focusing and on-off control of the electron beam are realized, and the performance of the scanning electron microscope is effectively improved.

[0028] like Figure 5-Figure 6 As shown, an embodiment of the present invention provides an electron beam blocker. The electron beam blocker of this embodiment adopts an innovative split electrode design, and its structure includes an annular substrate (middle pole piece), and the center of the substrate has a central through hole for the electron beam to pass through. The substrate is precisely divided into a left lobe electrode 201 and a right lobe electrode 202 along the axis of the central through hole. The two lobe electrodes are symmetrically distributed in space and isolated by an insulating pad 203. The left lobe electrode 201 and the right lobe electrode 202 are respectively provided with independent high-voltage interfaces 204. This design enables the electron beam blocker 2 to generate a transverse deflection electric field.

[0029] 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.

[0030] Based on the above structure, the embodiment of the present invention performs an electric field enhancement design on the central through hole of the electron beam blocker 2, and improves the control performance of the electrostatic lens on the electron beam by changing the local structure (i.e., the protrusion) of the electron beam blocker 2, thereby enhancing the working effect of the entire scanning electron microscope. This structural design starts from improving the effect of the electric field, and on the basis of not changing the core architecture of the overall device, specifically optimizes the behavior of the electron beam in the lateral deflection electric field, so as to achieve more precise electron beam control and better imaging quality.

[0031] 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, and 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, extend the field time of the electron beam 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, the doubling of 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 part of the external electric field to ensure that the electron beam is only affected by the transverse deflection electric field, further improving the accuracy of the electron beam control.

[0032] like Figure 1-Figure 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 comprises 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 end of the electron gun 701, and the lower pole piece 3 is close to the end of the sample 706. 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.

[0033] The electron beam blocker 2 of the embodiment of the present invention is integrated into the electrostatic lens and can be used as the middle pole piece of the electrostatic lens, realizing the functions of the electrostatic lens and the blanker at the same time, reducing the number of components, significantly reducing the volume of the scanning electron microscope equipment, reducing the weight, and facilitating the integrated design and application of the equipment. In terms of imaging quality, since the situation of using 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. Through the special structural design of the electron beam blocker 2, more precise control of the electron beam is achieved, while protecting the sample 706 from excessive radiation, the accuracy and clarity of the imaging are further improved.

[0034] 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.

[0035] In the present electrostatic lens structure, the electron beam blocker 2 plays a key role, and its voltage can be adjusted independently of the upper pole piece 1 and the lower pole piece 3, and the specific adjustment range is 3-12kV. By adjusting the voltage of the electron beam blocker 2, the function of adjusting the electron beam intersection point can be realized. For example, when the electron beam does not need to irradiate the sample 706 (such as the line scanning return position), the voltage of the left lobe electrode 201 or the right lobe electrode 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 avoiding unnecessary electron beam exposure.

[0036] 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, it is more compact in structure design and occupies less space. Figure 3 It can be observed intuitively that when the voltage of the electron beam blocker 2 changes between 10V and 15000V, the left lobe electrode 201 and the right lobe electrode 202 are equal in voltage. As the applied voltage changes, the electron beam emission angle changes regularly, 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.

[0037] Further, if Figure 7 As shown, a sleeve structure 302 overlapping with the central through hole is extended from the lower pole piece 3 on one side away from the electron beam blocker 2, and the sleeve structure 302 plays the role of a capture cage for the Blanker function in the entire system. Preferably, the central through hole and the sleeve structure 302 are coaxially arranged, which is conducive to increasing the sleeve structure 302's ability to capture electrons.

[0038] When the electrostatic lens performs the Blanker function, the voltage of the left lobe electrode 201 and the right lobe electrode 202 of the electron beam blocker 2 changes, causing a voltage difference between the left lobe electrode 201 and the right lobe electrode 202 to deflect the electron beam, and the deflected electrons will collide with the sleeve structure 302 of the lower pole piece 3. The sleeve structure 302 of the lower pole piece 3 can effectively limit the deflected electrons and the secondary electrons generated by the collision with the tube wall of the sleeve structure 302 as much as possible inside the sleeve, preventing these electrons from escaping to the external space. This feature is of great significance for realizing the Faraday cup function and accurately measuring current.

[0039] In actual operation, the left lobe electrode 201 and the right lobe electrode 202 of the electron beam blanker 2 are synchronously adjusted to a specific voltage in the initial stage, for example, the voltage of the electron beam blanker 2 is adjusted to 8000V and fixed. When the blanker function needs to be realized, only the voltage of the left lobe electrode 201 or the right lobe electrode 202 of the electron beam blanker 2 is changed to generate a voltage difference of 500V between the left lobe electrode 201 and the other lobe.

[0040] 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, it can be obtained that the central transverse electric field strength is about E = 10 5 V / m. Based on the force formula of electrons in electric fields, F = Eq (where q is the charge of the electron) and Newton's second law, F = ma (m is the mass of the electron), 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, and the electron velocity is v. According to the formula t = I / v, it can be calculated that the action time of the transverse electric field is about t = 10 - 10 s. Under the action of this voltage difference, the electron beam will produce a certain deflection. According to calculation, its deflection distance is about 0.1mm, and the corresponding deflection angle is about 30mrad. The distance from the electron beam leaving the electron beam blocker 2 to reaching the bottom of the lower pole piece 3 is about 20mm, and the corresponding deflection distance is about 1mm. At this time, the electron beam can just hit the aperture 702 (aperture 702 described below) set below the sleeve structure 302, achieving the maximum shielding of the deflected electron spot.

[0041] 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 of the aperture 303 is smaller than the diameter of the central through hole 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 there is a transverse deflection electric field, it can block the deflected electron spot to the maximum extent.

[0042] 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.

[0043] Furthermore, in the electrostatic lens structure of the present invention, in order 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. The insulating component not only plays the role of electrical insulation, preventing the current from being randomly conducted between different pole pieces and affecting the normal operation of the electrostatic lens, but also undertakes the important task of fixing the electron beam blocker 2, ensuring the stability of the entire electrostatic lens structure, and also improving the integration of the device.

[0044] The present invention selects ceramic balls 4 as insulating components because the ceramic balls 4 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.

[0045] Specifically, the lower side of the upper pole piece 1, the upper and lower sides of the electron beam blocker 2, and the upper side of the lower pole piece 3 are respectively provided with ceramic ball 4 fixing holes. The ceramic ball 4 fixing hole 103 of the upper pole piece 1 is coaxially aligned with the ceramic ball 4 fixing hole 206 on the upper side of the electron beam blocker 2, and the ceramic ball 4 fixing hole (not shown) of the lower pole piece 3 is coaxially aligned with the ceramic ball 4 fixing hole 206 on the lower side of the electron beam blocker 2. Such a coaxial alignment design enables the ceramic ball 4 to be accurately embedded in the corresponding ceramic ball 4 fixing hole, thereby ensuring that the relative position between the pole pieces is accurate and that the performance of the electrostatic lens is not affected.

[0046] To further ensure the stability and reliability of the structure, the number of fixing holes of the ceramic ball 4 is set to more than three. Multiple ceramic balls 4 are evenly distributed between the pole pieces, which can more evenly bear the weight of the electron beam blocker 2 and the forces from different directions, and effectively enhance the stability of the entire structure. In practical applications, this structural design can effectively reduce the displacement of the pole piece caused by external vibration or other factors, ensure that the electrostatic lens always maintains a good working condition during long-term use, and thus ensure that the scanning electron microscope can stably and accurately control the electron beam and obtain high-quality imaging effects.

[0047] 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. The connector plays a vital role in the entire structure, which not only makes the upper pole piece 1 and the lower pole piece 3 mechanically firmly connected, but also ensures the stable operation of the overall function of the electrostatic lens.

[0048] Specifically, a first through hole 102 for screws to pass through is specially provided on the upper pole piece 1, a second through hole 205 for screws to pass through is provided on the electron beam blocker 2, and a screw fixing hole (not shown) is correspondingly provided on the lower pole piece 3. The conductive connecting member used in the present invention is a conductive screw, which can realize the mechanical fixing function, meet the requirements of electrical conduction, and maintain electrical equipotential.

[0049] In 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 matches the screw fixing hole of the lower pole piece 3, so that the upper pole piece 1 and the lower pole piece 3 are firmly mechanically fixed together. The conductive screw only passes through the second through hole 205 and does not contact 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, and effectively prevents the position change between the pole pieces due to factors such as vibration and displacement during the operation of the equipment, thereby affecting the focusing and control effect of the electrostatic lens on the electron beam.

[0050] At the same time, the conductive properties of the conductive screws enable the upper pole piece 1 and the lower pole piece 3 to be electrically connected, and the two maintain the same potential. The upper pole piece 1 and the lower pole piece 3 maintain the same potential, which helps to form a specific electrostatic field distribution, and cooperates with the independently adjustable voltage of the electron beam blocker 2 to achieve precise focusing, deflection and other control functions of the electron beam. Through this carefully designed conductive connector structure, the dual stability of the electrostatic lens in mechanical structure and electrical performance is ensured, providing a strong guarantee for improving the imaging quality and work efficiency of the scanning electron microscope.

[0051] When the lower electrode is used as a Faraday cup and the current passing through is measured by the blanker function, the wire screws of the upper and lower electrodes need to be changed to insulating screws to ensure that all the 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.

[0052] Furthermore, the lower pole piece 3 is provided with a plurality of assembly holes 301 , through which fixing screws (not shown) pass. With the help of the fixing screws, the lower pole piece 3 is fixedly mounted on the scanning electron microscope.

[0053] In this embodiment, the electrostatic lens is fixedly assembled on the scanning electron microscope through the assembly hole, thereby ensuring the stability and detachability of the electrostatic lens.

[0054] 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 integration of internal components and the presence of electromagnetic noise can be solved.

[0055] Furthermore, the scanning electron microscope also includes an electron gun 701, which is used to generate an electron beam, and the electrostatic lens is used to perform multi-level focusing control on the electron beam generated by the electron gun 701.

[0056] 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 scanning electron microscope also includes an extraction stage 708, and the extraction stage 708, the electrostatic lens, the condenser array 703, and the objective lens system 705 are sequentially arranged in the path of the electron beam, wherein the upper pole piece 1 of the electrostatic lens can be used as an anode. The extraction stage 708 and the upper pole piece 1 work together to realize the function of the electrostatic lens, and the two work together to converge the electron beam. This design reduces the anode components, reduces the volume and weight of the SEM equipment, and is conducive to device integration.

[0057] In actual application scenarios, for the scanning electron microscope involved in the present invention, the high voltage applied to the upper pole piece 1 as recorded above is usually set at about 10kV. After the electron beam is emitted from the electron gun 701, it is acted on by the extraction stage, and the energy of the electron beam at this time is generally in the range of 1-5kV. The distance between the extraction stage and the upper pole piece 1 is approximately 10mm. In this interval, 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.

[0058] In another optional embodiment, the SEM further includes an extraction stage 708 and an anode 707, such as Figure 8 As shown on the right, the extraction stage 708, the anode 707, the condenser lens array 703, the electrostatic lens, and the objective lens system 705 are sequentially arranged on the path of the electron beam. At this time, the electrostatic lens can be at the same potential as the lens barrel, and the upper pole piece with a higher voltage is not required as the anode. The anode is set separately, and the voltage required by the objective lens system is not high. If the voltage of the objective lens system is not high, the excitation of the objective lens is not large, which can prevent the objective lens system from generating a magnetic saturation effect under a large excitation.

[0059] In summary, by setting the electrostatic lenses at different positions of the scanning electron microscope, the voltage excitation of the electrostatic lenses at different positions can be adjusted to change the electron optical path, reduce the aberration and improve the resolution.

[0060] The condenser lens array 703 includes a first condenser lens and a second condenser lens which are sequentially arranged along the beam direction.

[0061] 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 .

[0062] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight 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 electron beam blocker, characterized in that: It includes a substrate with a central through hole, the substrate is 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 are isolated 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.

2. The electron beam blanker according to claim 1, characterized in that: The protrusion is an annular structure or a flat plate structure which is arranged on the base and extends upward.

3. An electrostatic lens, comprising the electron beam blocker according to any one of claims 1 to 2, 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, and 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.

4. The electrostatic lens according to claim 3, characterized in that: 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.

5. The electrostatic lens according to claim 4, characterized in that: A diaphragm is arranged on one side of the sleeve structure away from the lower pole piece, and 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.

6. The electrostatic lens according to claim 5, characterized in that: An insulating component is 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 component.

7. The electrostatic lens according to claim 6, 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 ball is embedded in the corresponding ceramic ball fixing hole.

8. The electrostatic lens according to claim 3, characterized in that: It also includes a connecting piece, and the upper pole piece and the lower pole piece are fixed by the connecting piece.

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

10. The electrostatic lens according to claim 8, characterized in that: 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.

11. A scanning electron microscope, characterized in that: The scanning electron microscope comprises the electrostatic lens described in any one of claims 3-9.

12. The scanning electron microscope according to claim 11, characterized in that: It also includes an extraction stage, a condenser array and an objective lens system. 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.

13. The scanning electron microscope according to claim 11, 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.

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