Faraday cup for scanning electron microscope and scanning electron microscope system

Abstract

The utility model discloses a Faraday cup for a scanning electron microscope and a scanning electron microscope system. The Faraday cup comprises a cup cover, wherein the cup cover is provided with a first central through hole; the cup body comprises a cup body outer ring and a cup body inner ring provided with a second central through hole, and the portion, between the cup body outer ring and the cup body inner ring, of the cup body is concaved inwards to form an inwards-concaved circular ring blind hole; wherein the inner ring of the cup body is embedded into the first central through hole, and a gap is formed between the inner ring of the cup body and the first central through hole to form an annular incidence hole, so that an electron beam of a scanning electron microscope enters the concave circular ring blind hole along the annular incidence hole; and the insulating bottom support is provided with a third central through hole, and the third central through hole is communicated with the second central through hole to form a transmission path of an electron beam of the scanning electron microscope. By means of the scheme, electron beam intensity measurement and electron beam positioning can be achieved at the same time, and the electron beam measurement efficiency and measurement precision are greatly improved.

Description

Technical Field

[0001] The utility model generally relates to the technical field of scanning electron microscopes. More specifically, the utility model relates to a Faraday cup for a scanning electron microscope and a scanning electron microscope system. Background Art

[0002] The performance of electron beam devices such as scanning electron microscopes is closely related to the beam current intensity of the electron beam and the accuracy of electron beam alignment. Among them, the beam current intensity of the electron beam represents the number of electrons in the electron beam and can be represented by the magnitude of the current of the electron beam. Electron beam alignment usually refers to the precise coaxial alignment of the electron beam by applying a deflection electric field or a deflection magnetic field using the alignment circuit in the electron beam device to cause the electron beam to be deflected by force. In actual application scenarios, since the beam current intensity and coaxial alignment of the electron beam have a great influence on the accuracy of the electron beam device, a method is needed to accurately measure the beam current intensity and electron beam alignment of the electron beam. The Faraday cup is currently the most commonly used instrument for measuring the electron beam current, and its structure is simple, easy to process and convenient to operate.

[0003] However, the current Faraday cups are all used in the test link of the electron gun before the assembly of the electron beam device, and the functions are relatively single. Specifically, the current Faraday cup can only measure the beam current intensity of the electron beam. For electron beam alignment, basically, it relies on manually inputting the electromagnetic coil current or deflection electric field voltage during the later equipment debugging for repeated adjustment. This not only makes the electron beam alignment operation quite cumbersome, but also lacks effective positioning of the electron beam, resulting in poor accuracy of electron beam alignment.

[0004] In view of this, there is an urgent need to provide a Faraday cup for a scanning electron microscope for use in assembling a scanning electron microscope, so that the scanning electron microscope can achieve the position positioning of the electron beam while measuring the electron beam intensity, thereby realizing automatic electron beam alignment and greatly improving the measurement efficiency and measurement accuracy of the electron beam. Summary of the Utility Model

[0005] In order to solve at least one or more of the above-mentioned technical problems, the utility model proposes a Faraday cup solution for a scanning electron microscope in multiple aspects.

[0006] In a first aspect, the present utility model provides a Faraday cup for a scanning electron microscope, comprising: a cup lid 110, wherein a first central through hole 111 is formed in the cup lid 110; a cup body 120, wherein the cup body 120 includes a cup outer ring 121 and a cup inner ring 122 having a second central through hole 123, and a cup body portion between the cup outer ring 121 and the cup inner ring 122 is recessed inward to form an inner concave circular blind hole 203; wherein the cup inner ring 122 is embedded in the first central through hole 111 after the cup lid 110 is installed on the cup body 120, and is arranged to have a gap with the first central through hole 111 to form an annular incident hole 202, so that the electron beam of the scanning electron microscope enters the inner concave circular blind hole 203 along the annular incident hole 202; and an insulating base 130, wherein a third central through hole 131 is formed in the insulating base 130, and the third central through hole 131 communicates with the second central through hole 123 after the insulating base 130 is installed on the cup body 120 to form a transmission path 201 for the electron beam of the scanning electron microscope.

[0007] In some embodiments, the cup lid 110 and the cup body 120 are arranged as cylindrical shapes with corresponding thicknesses and the same diameters, wherein the thickness of the cup lid 110 is less than the thickness of the cup body 120.

[0008] In some embodiments, the inner circumferential wall surface 112 of the cup lid 110 is arranged as an inclined surface with an inclined angle.

[0009] In some embodiments, the cup inner ring 122 is higher than the cup outer ring 121, and the height of the cup inner ring 122 is flush with the height of the cup body 120 after the cup lid 110 is installed.

[0010] In some embodiments, the insulating base 130 includes a base outer ring 132 and a base inner ring 133, the third central through hole 131 is located within the base inner ring 133, wherein the base outer ring 132 is higher than the base inner ring 133, and a base portion between the base outer ring 132 and the base inner ring 133 is recessed inward to form an inner concave circular groove 601 for fitting the cup body 120.

[0011] In some embodiments, an inner concave groove 501 adapted to the base inner ring 133 is provided at the bottom of the cup body 120, wherein the cup body 120 is embedded in the inner concave circular groove 601, and the outer wall surface of the cup outer ring 121 abuts against the inner wall surface of the base outer ring 132, and the base inner ring 133 is engaged with the inner concave groove 501 of the cup body.

[0012] In some embodiments, the cup lid 110, the cup body 120 and the insulating base 130 are detachably assembled.

[0013] In some embodiments, both the cup lid 110 and the cup body 120 are made of beryllium copper, and the insulating base 130 is made of ceramic material.

[0014] In a second aspect, the present utility model provides a scanning electron microscope system, comprising: a scanning electron microscope; and the Faraday cup described in the foregoing first aspect.

[0015] In some embodiments, the Faraday cup is assembled inside the lens barrel of the scanning electron microscope, and the surface of the cup lid of the Faraday cup faces the light source of the scanning electron microscope.

[0016] With the Faraday cup for a scanning electron microscope provided as above, in the embodiments of the present utility model, by respectively providing central through holes for the cup lid, the cup body, and the insulating base, wherein the third central through hole of the insulating base can communicate with the second central through hole of the cup body to form a transmission path for the electron beam of the scanning electron microscope to transmit the electron beam and achieve real-time detection. Further, the cup body is provided with a cup outer ring, a cup inner ring, and an inner concave circular ring blind hole, wherein the cup inner ring can be embedded in the first central through hole of the cup lid and is arranged to have a gap with the first central through hole to form an annular incident hole, so that the electron beam of the scanning electron microscope enters the inner concave circular ring blind hole along the annular incident hole. In an implementation scenario, by scanning the surface of the cup lid of the Faraday cup with the scanning electron microscope, and there is a step peak current curve when passing through the annular incident hole, the intensity information and positioning information of the measured electron beam can be obtained. Based on this, the intensity and positioning of the electron beam can be detected simultaneously and in real time, thereby realizing automatic centering of the electron beam and greatly improving the measurement efficiency and measurement accuracy of the electron beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features, and advantages of the exemplary embodiments of the present utility model will become readily understood. In the drawings, several embodiments of the present utility model are shown in an exemplary rather than restrictive manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0018] Figure 1 is an exemplary schematic diagram showing a Faraday cup according to an embodiment of the present utility model;

[0019] Figure 2 is an exemplary cross-sectional view showing a Faraday cup according to an embodiment of the present utility model;

[0020] Figure 3 is an exemplary schematic diagram showing the cup lid and the cup body of a Faraday cup according to an embodiment of the present utility model;

[0021] Figure 4is an exemplary cross-sectional view showing the cup lid and cup body of a Faraday cup according to an embodiment of the present invention;

[0022] Figure 5 is an exemplary schematic diagram showing the insulating base of a Faraday cup according to an embodiment of the present invention;

[0023] Figure 6 is an exemplary schematic diagram showing the cup lid of a Faraday cup according to an embodiment of the present invention;

[0024] Figure 7 is an exemplary simplified diagram showing a Faraday cup assembled in a scanning electron microscope according to an embodiment of the present invention;

[0025] Figure 8 is an exemplary flowchart showing a method for measuring an electron beam based on a Faraday cup according to an embodiment of the present invention;

[0026] Figure 9 is an exemplary schematic diagram showing the measurement of an electron beam based on a Faraday cup according to an embodiment of the present invention;

[0027] Figure 10 is an exemplary schematic diagram showing the alignment calibration of an electron beam. Detailed Embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] It should be understood that the terms "including" and "comprising" used in the specification and claims of the present invention indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0030] It should also be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification and claims of the present invention, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms. It should be further understood that the term " / and / " used in the specification and claims of the present invention refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0031] As used in this specification and the claims, the term "if" may be construed, depending on the context, as "when" or "once" or "in response to determining" or "in response to detecting". Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be construed, depending on the context, to mean "once determined" or "in response to determining" or "once [the described condition or event] is detected" or "in response to detecting [the described condition or event]".

[0032] It should be understood that a conventional Faraday cup generally includes three parts: a cup lid with a small hole in the center, a cup body, and an insulating base. In an implementation scenario, an electron beam enters the interior of the cup body of the Faraday cup through the small hole in the cup lid to achieve the collection of the electron beam. It can only measure the beam current intensity of the electron beam, and its function is too single. Additionally, since the conventional Faraday cup only has a small hole in the center for collection and there is no transmission channel for the electron beam, the conventional Faraday cup can only be used for testing the electron gun of a scanning electron microscope before assembling electron beam devices such as a scanning electron microscope, and cannot achieve the measurement of the electron beam intensity and the alignment of the electron beam during the real-time detection process of electron beam devices such as a scanning electron microscope. For electron beam alignment, it basically relies on manually inputting the electromagnetic coil current or the deflection electric field voltage during the later equipment debugging for repeated adjustment. This not only makes the electron beam alignment operation quite cumbersome but also lacks effective positioning of the electron beam.

[0033] Based on this, embodiments of the present utility model open an annular incident hole and a transmission path in the Faraday cup, enabling it to be assembled and used inside a scanning electron microscope, capable of simultaneously and real-time detecting the electron beam intensity and the positioning of the electron beam, thereby achieving automatic electron beam alignment and greatly improving the measurement efficiency and measurement accuracy of the electron beam.

[0034] The following will describe in detail the specific embodiments of the present utility model with reference to the accompanying drawings.

[0035] Figure 1 is an exemplary schematic diagram showing a Faraday cup according to an embodiment of the present utility model. As Figure 1As shown in the figure, there is a Faraday cup 10, which includes a cup cover 110, a cup body 120, and an insulating base 130. The cup cover 110 and the cup body 120 can be set as cylindrical shapes with corresponding thicknesses and the same diameters, and the thickness of the cup cover 110 is less than that of the cup body 120. In some embodiments, the cup cover 110, the cup body 120, and the insulating base 130 are detachably assembled. For example, the figure shows the overall assembled Faraday cup. In an exemplary scenario, the cup cover 110 and the cup body 120 can be assembled and fixed by, for example, screws, and the cup body 120 and the insulating base 130 can be assembled and fixed by, for example, screws or set screws. In some embodiments, both the cup cover 110 and the cup body 120 are made of beryllium copper, and the insulating base 130 is made of ceramic material. Among them, beryllium copper not only has high electrical conductivity but also excellent workability and corrosion resistance, while ceramic has excellent insulation performance.

[0036] The figure further shows that the Faraday cup of the embodiment of the present invention is provided with a transmission path 201 and an annular incident hole 202 located on the surface of the cup cover. The aforementioned transmission path 201 can transmit an electron beam, and the electron beam can enter the cup body 120 along the annular incident hole 202. In an implementation scenario, by assembling the whole Faraday cup into the lens barrel of a scanning electron microscope, the intensity and position of the electron beam can be measured.

[0037] Figure 2 is an exemplary cross-sectional view showing the Faraday cup according to the embodiment of the present invention. It should be understood that Figure 2 is the above Figure 1 a specific embodiment of the Faraday cup in, so the above description about Figure 1 also applies to Figure 2 .

[0038] As Figure 2 shown in, the cup cover 110 is provided with a first central through hole 111. The cup body 120 may include a cup outer ring 121 and a cup inner ring 122 provided with a second central through hole 123. The cup body portion between the aforementioned cup outer ring 121 and the cup inner ring 122 is recessed inward to form an inner concave circular ring blind hole 203, and the cup inner ring 122 is embedded in the first central through hole 111 after the cup cover 110 is installed on the cup body 120, and is set to have a gap with the first central through hole 111 to form the aforementioned annular incident hole 202. That is, the diameter of the cup inner ring 122 is smaller than the diameter of the first central through hole 111, and there will be a gap between the cup inner ring 122 and the first central through hole 111 after assembly, thus forming the annular incident hole 202. In some embodiments, the cup inner ring 122 is higher than the cup outer ring 121, and the height of the cup inner ring 122 is flush with the height of the cup body 120 after the cup cover 110 is installed.

[0039] Furthermore, the insulating base 130 is provided with a third central through hole 131, and after the cup body 120 is equipped with the insulating base 130, the third central through hole 131 communicates with the second central through hole 123 to form a transmission path 201 for the electron beam of the scanning electron microscope. That is to say, the center of the Faraday cup is a through hole. When assembled in the lens barrel of the scanning electron microscope, the electron beam can be transmitted along the through hole (i.e., the transmission path) in the Faraday cup to detect the sample.

[0040] In some embodiments, the insulating base 130 may include an outer base ring 132 and an inner base ring 133, and the above-mentioned third central through hole 131 is located within the inner base ring 133. Among them, the outer base ring 132 is higher than the inner base ring 133, and the base part between the outer base ring 132 and the inner base ring 133 is recessed inward to form an inner concave circular groove 601 (for example Figure 5 as shown) to fit the cup body 120. Correspondingly, a cup body embedded groove 501 (for example Figure 4 as shown) adapted to the inner base ring 133 is provided at the bottom of the cup body 120. The cup body 120 is embedded in the aforementioned inner concave circular groove 601, and the outer wall surface of the outer cup ring 121 abuts against the inner wall surface of the outer base ring 132, and the inner base ring 133 is engaged with the cup body embedded groove 501.

[0041] Figure 3 is an exemplary schematic diagram showing the cup lid and the cup body of the Faraday cup according to an embodiment of the present invention. As Figure 3 shown, the inner cup ring 122 of the assembled cup body 120 is embedded in the first central through hole 111 of the cup lid 110. Since the diameter of the inner cup ring 122 is smaller than the diameter of the first central through hole 111, a gap is formed between the inner cup ring 122 and the first central through hole 111 to form an annular incident hole 202. The figure further shows that the height of the inner cup ring 122 is flush with the height of the cup body 120 after the cup lid 110 is installed.

[0042] Figure 4 is an exemplary cross-sectional view showing the cup lid and the cup body of the Faraday cup according to an embodiment of the present invention. As Figure 4 shown, the inner cup ring 122 is provided with a second central through hole 123, and the second central through hole 123 communicates with the third central through hole 131 of the insulating base 130 to form a transmission path 201 for the electron beam of the scanning electron microscope (for example Figure 2As shown). The cup body portion between the outer cup ring 121 and the inner cup ring 122 of the cup body 120 is recessed inward to form a concave circular blind hole 203, and the inner cup ring 122 is embedded in the first central through hole 111 after the cup cover 110 is installed on the cup body 120, and is arranged to have a gap with the first central through hole 111 to form the aforementioned annular incident hole 202. The figure further shows that a cup body embedded groove 501 is provided at the bottom of the cup body 120, which is adapted to the inner bottom ring 133 to complete the assembly of the cup body 120 and the insulating bottom support 130.

[0043] Figure 5 FIG. is an exemplary schematic diagram showing an insulating bottom support of a Faraday cup according to an embodiment of the present invention. As Figure 5 shown in the figure, the insulating bottom support 130 may include a bottom support outer ring 132 and a bottom support inner ring 133. The above-mentioned third central through hole 131 is located within the bottom support inner ring 133. The bottom support outer ring 132 is higher than the bottom support inner ring 133, and the bottom support portion between the bottom support outer ring 132 and the bottom support inner ring 133 is recessed inward to form a concave circular groove 601. When assembling the cup body 120 and the insulating bottom support 130, the cup body 120 is embedded in the aforementioned concave circular groove 601, and the outer wall surface of the outer cup ring 121 abuts against the inner wall surface of the bottom support outer ring 132, and the bottom support inner ring 133 is engaged with the cup body embedded groove 501 (for example, as shown in the above Figure 2 figure).

[0044] Figure 6 FIG. is an exemplary schematic diagram showing a cup cover of a Faraday cup according to an embodiment of the present invention. As Figure 6 shown in the figure, the inner ring wall surface 112 of the cup cover 110 is also provided with an inclined surface having an inclination angle. Based on this, through the inclined wall surface, the electrons ejected from the concave circular blind hole of the cup body can be reflected by the inner ring wall surface of the cup cover 110, reducing the number of electrons directly escaping from the Faraday cup through the annular incident hole, improving the collection rate of the Faraday cup for the electron beam, and thus enhancing the measurement accuracy of the electron beam intensity.

[0045] According to the foregoing, by integrally assembling the Faraday cup into the lens barrel of a scanning electron microscope, the method for measuring an electron beam based on the Faraday cup according to the embodiment of the present invention can be realized. The following Figure 7 exemplarily shows a simplified diagram of the overall assembly of the Faraday cup in the lens barrel of a scanning electron microscope.

[0046] Figure 7 FIG. is an exemplary simplified diagram showing the assembly of a Faraday cup according to an embodiment of the present invention in a scanning electron microscope. As Figure 7As shown in the figure, the Faraday cup 10 is integrally assembled inside the barrel 801 of a scanning electron microscope, where the surface of the cup lid 110 of the Faraday cup faces the electron gun 802 of the scanning electron microscope. In some embodiments, one end of the inner core of an insulated wire can be connected to the inside of the cup body of the Faraday cup. Specifically, one end of the inner core of the insulated wire is connected to the inner concave circular ring blind hole (such as the inner concave circular ring blind hole 203 in the above Figure 2 ) inside the cup body. The other end of the insulated wire is connected to an external current measuring device 803.

[0047] In one implementation scenario, first, turn on the vacuum pump of the scanning electron microscope. After the vacuum degree inside the scanning electron microscope reaches the working requirement, set the emission parameters such as the tip current and acceleration voltage of the electron gun 802. Then, turn on the electron gun 802 to emit an electron beam (as shown by the dotted line in the figure), and apply an excitation to the deflector so that the electron beam horizontally scans the surface of the cup lid 110 of the Faraday cup in a straight line, for example, from left to right (as shown by the arrow in the figure). During the scanning process, when the electron beam passes through the annular incident hole 202, it enters the inner concave circular ring blind hole inside the cup body 120 of the Faraday cup. After horizontally scanning in a straight line, for example, from left to right, the external current measuring device 803 will output a corresponding current curve graph according to the situation of the electron beam collected by the inner concave circular ring blind hole inside the cup body 120 of the Faraday cup. Further, according to the current curve graph, the intensity and position of the electron beam can be measured simultaneously, thereby realizing electron beam alignment.

[0048] It should be understood that the transmission path of the Faraday cup is omitted in the above Figure 7 schematic diagram. In the implementation scenario, the electron beam can be transmitted through the transmission path to irradiate the surface of the sample for real-time detection.

[0049] Figure 8 is an exemplary flowchart showing a method 800 for measuring an electron beam based on a Faraday cup according to an embodiment of the present invention. As described above, the Faraday cup can include a cup lid, a cup body, and an insulating base. The cup lid, the cup body, and the insulating base can be assembled into a whole and assembled inside the barrel of the scanning electron microscope, and are coaxial with the barrel of the scanning electron microscope, while the surface of the cup lid faces the electron beam light source (i.e., the electron gun of the scanning electron microscope). Further, central through holes are respectively opened in the cup lid, the cup body, and the insulating base, and the central through holes communicate to form a transmission path for the electron beam to transmit the electron beam, so as to ensure real-time detection. In addition, an annular incident hole is provided on the surface of the cup lid so that the electron beam enters the cup body of the Faraday cup along the annular incident hole, thereby collecting electrons. For more details about the Faraday cup, reference can be made to the above Figures 1 - 7 description, and the present invention will not be elaborated here.

[0050] Specifically, as Figure 8As shown, at step S801, a current curve graph generated by the scanning electron microscope scanning the surface of the lid of the Faraday cup is obtained, where there is a step peak in the current curve graph when the scanning electron microscope scans through the annular incident hole. In some implementation scenarios, one end of the inner core of the insulating wire can be connected to the inside of the cup body of the Faraday cup, and the other end of the insulating wire is connected to an external current measuring device to obtain the aforementioned current curve graph. Specifically, first, turn on the vacuum pump of the scanning electron microscope. After the vacuum degree inside the scanning electron microscope reaches the working requirement, set the emission parameters such as the tip current and acceleration voltage of the electron gun. Then, turn on the electron gun and apply an excitation to the deflector to make the electron beam scan the surface of the lid of the Faraday cup horizontally (or vertically) along a straight line from left to right (or from top to bottom). During the scanning process, when the electron beam passes through the annular incident hole, it enters the cup body of the Faraday cup. After scanning horizontally (or vertically) along a straight line from left to right (or from top to bottom), the external current measuring device will output a corresponding current curve graph according to the electron beam situation collected in the cup body of the Faraday cup.

[0051] It can be understood that when the electron beam scans the surface of the cup body of the Faraday cup or passes through the transmission path (i.e., the central through hole of the Faraday cup), the Faraday cup does not collect the electron beam, and its feedback in the current curve graph is a value of 0. When the electron beam scans to pass through the annular incident hole of the Faraday cup, the electron beam enters the cup body of the Faraday cup through the annular incident hole and collects the electron beam, and there will be a corresponding step peak in the current curve graph (for example Figure 9 as shown).

[0052] Based on the obtained current curve graph, at step S802, the intensity information of the electron beam emitted by the scanning electron microscope is determined according to the peak value of the step peak. In one implementation scenario, the peak value of the step peak in the current curve graph (i.e., the ordinate value in the current curve graph) is the intensity of the electron beam. Further, at step S803, the step peak spacing in the current curve graph and the size of the annular incident hole are obtained, and at step S804, the positioning information of the electron beam is determined based on the step peak spacing and the size. Among them, the positioning information of the electron beam can achieve electron beam alignment. In some embodiments, the size of the aforementioned annular incident hole can be, for example, the radius of the annular incident hole, which can be obtained by measuring the actual design size of the Faraday cup.

[0053] In one embodiment, the offsets corresponding to the deflection point of the electron beam in the first direction and the second direction can be calculated based on the step peak spacing and the radius of the annular incident hole, so as to determine the positioning information of the electron beam according to the offsets corresponding to the deflection point of the electron beam in the first direction and the second direction. That is, the step peak spacing of the current curve graph contains the electron beam position information. By combining the radius of the annular incident hole to calculate the offset of the electron beam deflection point, the positioning information of the electron beam can be obtained.

[0054] In one implementation scenario, the first distance that the scanning electron microscope scans through the annular incident aperture can be calculated based on the step peak spacing, so as to calculate the offset corresponding to the deflection point of the electron beam in the first direction according to the first distance and the radius of the annular incident aperture. Further, the first distance that the scanning electron microscope scans through the annular incident aperture and the second distance between the deflection point of the electron beam and the annular incident aperture are calculated based on the step peak spacing, and then the offset corresponding to the deflection point of the electron beam in the second direction is calculated according to the first distance and the second distance. Specifically, the offset of the deflection point can be calculated according to the planar geometric relationships such as the positions and lengths among the electron beam deflection point, the point where the electron beam scans through the annular incident aperture, and the axis center.

[0055] It should be understood that the offsets corresponding to the foregoing first direction and second direction are the horizontal and vertical coordinates of the electron beam deflection point during horizontal scanning or vertical scanning of the electron beam. Among them, during horizontal scanning, the offsets corresponding to the foregoing first direction and second direction are the vertical coordinate and the horizontal coordinate of the electron beam deflection point respectively; during vertical scanning (such as Figure 9 shown), the offsets corresponding to the foregoing first direction and second direction are the horizontal coordinate and the vertical coordinate of the electron beam deflection point respectively. The calculation of the quantity of the positioning information of the electron beam will be described in detail later in conjunction with Figure 9

[0056] Further, after obtaining the offset of the electron beam as described above, the target alignment parameter required for electron beam alignment can be calculated, and the target alignment parameter is applied to the deflector of the scanning electron microscope, so that the deflector of the scanning electron microscope deflects the electron beam according to the positioning information of the electron beam to achieve electron beam alignment. In some embodiments, the foregoing target alignment parameter at least includes a voltage excitation value or a current excitation value. It can be understood that the deflector of the scanning electron microscope is composed of electrode plates or electromagnetic coils, and they respectively use the electric field force and the Lorentz force to do work to cause the electron beam to deflect. In some implementation scenarios, according to the current acceleration voltage value of the electron beam, the time for the electron beam to pass through the deflector can be calculated to obtain the electric field force or Lorentz force required to achieve the target offset when the electron beam passes through the deflector. Then, according to the electric field force or Lorentz force required to achieve the target offset, the voltage excitation value of the electrode plate in the electric deflection or the current excitation value of the electromagnetic deflection coil required for electron beam alignment is calculated, and the automatic alignment of the electron beam is achieved by applying the calculated current excitation value or voltage excitation value to the deflector.

[0057] It should be understood that in actual application scenarios, there will be a certain angular tilt in the incident electron beam, resulting in a deviation in the positioning of the electron beam, and thus the electron beam cannot be accurately centered. Therefore, the embodiments of the present invention also involve obtaining the deflection angles corresponding to the annular incident holes scanned by the electron beam of the scanning electron microscope in different directions, and adjusting the electron beam according to the differences between the deflection angles until the deflection angles are the same, so as to calibrate the centering of the electron beam. As an example, it is possible to scan horizontally to the left through the annular incident hole and scan horizontally to the right through the annular incident hole, so as to calculate the deflection angles of the electron beam when passing through the annular incident hole to the left and to the right respectively, and then calibrate the centering of the electron beam according to the deflection angle differences in the two directions. Similarly, it is possible to scan vertically downward through the annular incident hole and scan vertically upward through the annular incident hole, so as to calculate the deflection angles of the electron beam when passing through the annular incident hole upward and downward respectively, and then calibrate the centering of the electron beam according to the deflection angle differences in the two directions. The calibration of the electron beam centering will be described in detail later in conjunction with Figure 10 calibrating the centering of the electron beam.

[0058] Combined with the above description, in the embodiments of the present invention, a Faraday cup having at least a transmission path and an annular incident hole on the surface of the cup lid is integrally assembled into the lens barrel of a scanning electron microscope, and the surface of the cup lid of the Faraday cup is linearly scanned by the scanning electron microscope to obtain a current curve graph generated during the scanning process. Among them, there is a step peak in the current curve graph when scanning through the annular incident hole, which contains the intensity and position information of the electron beam. Therefore, the embodiments of the present invention can simultaneously and real-time detect the intensity of the electron beam and the positioning of the electron beam, thereby realizing automatic centering of the electron beam, greatly improving the measurement efficiency and measurement accuracy of the electron beam. In addition, the embodiments of the present invention also calibrate the centering of the electron beam to calibrate the position offset and angle offset of the electron beam, thereby further improving the accuracy of the electron beam centering.

[0059] Figure 9 is an exemplary schematic diagram showing the measurement of an electron beam based on a Faraday cup according to an embodiment of the present invention. As shown in Figure 9 FIG. (a) shows an example diagram of an electron beam scanning the cup lid 110 (omitting the transmission path) of the Faraday cup. As an example, assume that point O is the point at the axis center and define it as the origin in the plane, and assume that the electron beam deflection point is at point A. In this scenario, a raster scan is performed once in the vertical direction using a scanning electron microscope, for example, scanning vertically upward from point A through point B, and then scanning vertically downward from above through points C and D. Then, the external current measurement device will output a corresponding current curve graph according to the electron beam situation collected in the cup body of the Faraday cup. As described above, there is a step peak in the current curve graph when the electron beam scans through the annular incident hole, and the rest of the positions feedback 0 values. Therefore, there will be step peaks at B, C, and D, and the value at A is 0. For example Figure 9Figure (b) is the current curve corresponding to the output.

[0060] Figure 9 Points a, b, c, and d in Figure (b) correspond to the positions of points A, B, C, and D respectively. Among them, the three step peaks at b, c, and d are the step changes in the current intensity values generated when the Faraday cup successfully collects the electron beam current when the electron beam scans to the annular incident hole. The peak value I0 of the step peak is the measured electron beam intensity. In addition, according to the spacing between the step peaks, the distance between each point can be determined. For example, the step peak spacing between the step peaks at c and d represents the distance between points C and D, and the step peak spacing between the step peaks at a and b represents the distance between points A and B. In some embodiments, the offset of the electron beam deflection point can be calculated through the plane geometric relationship of each point.

[0061] As an example, assume that the offsets of the electron beam deflection point A in the first direction and the second direction (i.e., the horizontal and vertical coordinates) are denoted as x A , y A , and x A , y A can be calculated respectively based on the following formulas:

[0062]

[0063] Among them, OB represents the radius of the annular incident hole, CD represents the first distance that the scanning electron microscope scans through the annular incident hole, and AB represents the second distance between the electron beam deflection point and the annular incident hole. According to the above, CD and AB can be calculated based on the step peak spacing in the current curve graph, and OB can be obtained from the actual design size of the Faraday cup.

[0064] It can be understood that the "±" in the vertical coordinate x A in the above formula (1) represents the direction of the deflection point A. In some embodiments, a raster scan in the horizontal direction can be performed again using a scanning electron microscope. For example Figure 9 as shown in Figure (b), scan horizontally left from point A through point E, and then scan horizontally right from the left through points F and G to obtain the corresponding current curve graph. Similarly, the distances AE and FG can be obtained based on the step peak distances on the current curve graph. In this scenario, when AE < FG / 2, it can be determined that the abscissa of the deflection point A is negative; when AE > FG / 2, it can be determined that the abscissa of the deflection point A is positive.

[0065] Similarly, if scanned in the horizontal direction, x A , y AThey are the vertical coordinate and the horizontal coordinate respectively. Based on the aforementioned offset, by applying, for example, a voltage excitation value or a current excitation value to the deflector of the scanning electron microscope, the deflector of the scanning electron microscope deflects the electron beam deflection point A to the axis O according to the aforementioned offset, and automatic electron beam alignment can be achieved.

[0066] Figure 10 is an exemplary schematic diagram showing the calibration of the electron beam alignment according to an embodiment of the present invention. As Figure 10 shown in the figure, assuming that the electrons perform raster scanning in the horizontal direction, it first scans to the left to the annular incident hole, and the corresponding deflection angle is denoted as α. Then, it scans to the right to the annular incident hole, and the corresponding deflection angle is denoted as β. In the implementation scenario, according to the angle bisector theorem in plane geometry, it can be known that:

[0067]

[0068] where OB = OD, from which we can obtain

[0069] As can be seen from the figure, the electron beam is inclined to the left, so the length of BS is greater than the length of DS. Correspondingly, the deflection angle β is greater than the deflection angle α, and thus the side with the smaller deflection angle (i.e., the left side) is the inclination direction of the electron beam. In this scenario, according to the difference between the deflection angles, an excitation can be applied to the side with the larger deflection angle (i.e., the right side) to correct the inclination angle of the electron beam itself. By cycling in this way until the deflection angle α is equal to the deflection angle β, that is, the deflection excitation is the same when scanning to points B and D on both sides respectively. At the same time, the electron beam coordinates are also aligned to the axis point O, that is, the angle correction and alignment of the inclined electron beam are completed. Similarly, the calibration in the vertical direction can be completed. In some embodiments, the difference in the deflection angles can be determined by the excitation applied by the deflector during scanning.

[0070] In one embodiment, the embodiment of the present invention further provides a scanning electron microscope system, which includes a scanning electron microscope and the Faraday cup of the embodiment of the present invention. Among them, the Faraday cup is assembled in the lens barrel of the scanning electron microscope, and the surface of the cup cover of the Faraday cup faces the light source (i.e., the electron gun) of the scanning electron microscope. Specifically, the Faraday cup is integrated into the lens barrel of the scanning electron microscope, so that while having the function of measuring the electron beam current intensity, it can also position the electron beam, automatically achieve electron beam alignment, and calibrate the position offset and angle offset of the electron beam. For more details about measuring the electron beam and the specific structure of the Faraday cup and its integration, reference can be made to the above Figures 1 - 9 description, and the present invention will not be elaborated herein.

[0071] Although multiple embodiments of the present utility model have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art can conceive of many changes, alterations, and alternative ways without departing from the spirit and idea of the present utility model. It should be understood that various alternative solutions to the embodiments of the present utility model described herein may be adopted in the practice of the present utility model. The appended claims are intended to define the protection scope of the present utility model and thus cover equivalents or alternative solutions within the scope of these claims.

Claims

1. A Faraday cup for a scanning electron microscope, characterized in that, Comprising: A cup lid (110), wherein the cup lid (110) is provided with a first central through hole (111); A cup body (120), wherein the cup body (120) includes a cup outer ring (121) and a cup inner ring (122) provided with a second central through hole (123), and the cup body part between the cup outer ring (121) and the cup inner ring (122) is recessed inward to form an inner concave circular blind hole (203); wherein the cup inner ring (122) is embedded in the first central through hole (111) after the cup lid (110) is installed on the cup body (120), and is arranged to have a gap with the first central through hole (111) to form an annular incident hole (202), so that the electron beam of the scanning electron microscope enters the inner concave circular blind hole (203) along the annular incident hole (202); and An insulating base (130), wherein the insulating base (130) is provided with a third central through hole (131), and the third central through hole (131) communicates with the second central through hole (123) after the insulating base (130) is installed on the cup body (120) to form a transmission path (201) for the electron beam of the scanning electron microscope.

2. The Faraday cup according to claim 1, wherein The cup lid (110) and the cup body (120) are arranged to be cylindrical with corresponding thicknesses and the same diameters, and the thickness of the cup lid (110) is less than the thickness of the cup body (120).

3. The Faraday cup according to claim 1 or 2, characterized in that, The inner circumferential wall surface (112) of the cup lid (110) is arranged to be an inclined plane with an inclined angle.

4. The Faraday cup according to claim 3, characterized in that, The cup inner ring (122) is higher than the cup outer ring (121), and the height of the cup inner ring (122) is flush with the height of the cup body (120) after the cup lid (110) is installed on the cup body (120).

5. The Faraday cup according to claim 4, characterized in that, The insulating base (130) includes a base outer ring (132) and a base inner ring (133), the third central through hole (131) is located within the base inner ring (133), wherein the base outer ring (132) is higher than the base inner ring (133), and the base part between the base outer ring (132) and the base inner ring (133) is recessed inward to form an inner concave circular groove (601) for fitting the cup body (120).

6. The Faraday cup according to claim 5, characterized in that, The bottom of the cup body (120) is provided with a cup inner embedding groove (501) adapted to the base inner ring (133), wherein the cup body (120) is embedded in the inner concave circular groove (601), and the outer circumferential wall surface of the cup outer ring (121) abuts against the inner circumferential wall surface of the base outer ring (132), and the base inner ring (133) engages with the cup inner embedding groove (501).

7. The Faraday cup according to claim 1, characterized in that, The cup lid (110), the cup body (120) and the insulating base (130) are detachably assembled.

8. The Faraday cup according to claim 1, characterized in that, The cup lid (110) and the cup body (120) are both made of beryllium copper, and the insulating base (130) is made of ceramic material.

9. A scanning electron microscope system, characterized in that, Comprising: A scanning electron microscope; And A Faraday cup according to any one of claims 1-8.

10. The scanning electron microscope system according to claim 9, wherein The Faraday cup is assembled inside the lens barrel of the scanning electron microscope, and the surface of the cup cover of the Faraday cup faces the light source of the scanning electron microscope.

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