CN109585244B - High power density electron beam focusing device - Google Patents
High power density electron beam focusing device Download PDFInfo
- Publication number
- CN109585244B CN109585244B CN201811281545.9A CN201811281545A CN109585244B CN 109585244 B CN109585244 B CN 109585244B CN 201811281545 A CN201811281545 A CN 201811281545A CN 109585244 B CN109585244 B CN 109585244B
- Authority
- CN
- China
- Prior art keywords
- electron beam
- magnetic field
- pole shoe
- lens module
- module
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000010894 electron beam technology Methods 0.000 title claims abstract description 141
- 230000003287 optical effect Effects 0.000 claims abstract description 11
- 230000000712 assembly Effects 0.000 claims description 6
- 238000000429 assembly Methods 0.000 claims description 6
- 238000003384 imaging method Methods 0.000 claims description 6
- 230000008685 targeting Effects 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 2
- 230000004075 alteration Effects 0.000 abstract description 14
- 230000009467 reduction Effects 0.000 abstract description 12
- 230000005540 biological transmission Effects 0.000 abstract description 8
- 239000000463 material Substances 0.000 description 13
- 230000005284 excitation Effects 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 230000007704 transition Effects 0.000 description 6
- 238000001514 detection method Methods 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 230000005389 magnetism Effects 0.000 description 5
- 230000001133 acceleration Effects 0.000 description 3
- 239000000306 component Substances 0.000 description 3
- 238000010603 microCT Methods 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 239000013077 target material Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910001141 Ductile iron Inorganic materials 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 229910000737 Duralumin Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011796 hollow space material Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
- H01J37/10—Lenses
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/252—Tubes for spot-analysing by electron or ion beams; Microanalysers
- H01J37/256—Tubes for spot-analysing by electron or ion beams; Microanalysers using scanning beams
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
- H01J37/261—Details
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
- H01J37/3002—Details
Landscapes
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Electron Beam Exposure (AREA)
Abstract
The invention discloses an electron beam focusing device with high power density, which comprises a condenser lens module, an auxiliary condenser lens module and an objective lens module which are sequentially arranged along the emission direction of an electron beam; the condenser lens module is used for forming a first magnetic field so as to enable the electron beams to form a cross point; the auxiliary condenser lens module is used for forming a second magnetic field so that the motion track of the electron beam is parallel to the optical axis to form a parallel beam, and the magnetic field intensity of the first magnetic field is larger than that of the second magnetic field; the objective lens module is used for forming a third magnetic field so that the electron beams are focused to the target plane. The cross-parallel-focusing control of the electron beam is realized by adopting a multi-lens combination mode of a condenser lens, an auxiliary condenser lens and an objective lens, so that the high reduction magnification, small aberration and high-efficiency beam transmission of an electron beam system are obtained.
Description
Technical Field
The invention belongs to the technical field of three-dimensional nondestructive microscopic observation, and particularly relates to an electron beam focusing device.
Background
The electron beam focusing device with high power density can be used in an imaging device which utilizes an electron beam to bombard a target material to generate corresponding rays to scan a sample, for example, Micro-Computed Tomography (Micro-CT) is a nondestructive microscopic imaging technology which utilizes X rays to scan the sample and inverts scanning data into a three-dimensional image, can display characteristic information such as internal structure, density, defects and the like of the detected sample at micron level or even submicron level, is widely applied to detection in the fields of life science, materials science, geology and the like, and is the development direction of the Micro-CT technology for improving detection resolution and efficiency. An electron beam targeted X-ray source is one of the core components of micro CT, and the detection resolution and efficiency are directly related to the focal spot size and power density of the source.
An electron beam targeting X-ray source generally adopts a multi-lens focusing system, a magnetic lens close to a target plane is called an objective lens, and a magnetic lens far away from the target plane is a condenser lens. The incident electron beam on the target surface generates X-rays after acting with the target material, wherein the beam spot of the incident electron beam determines the focal spot size of an X-ray source, and the beam current and the acceleration voltage determine the power of the X-rays. When the acceleration voltage is fixed, the power density of an X-ray source generated after an electron beam with larger beam current and smaller beam spot bombards a target plane is higher, and the detection efficiency and the resolution of an X-ray microscopic imaging system are also higher. However, in the magnetic lens focusing system, as is known from the lagrange-helmholtz relationship in the electron optical theory, the linear reduction magnification and the angular magnification are reciprocal. If a small electron beam spot is obtained by simply adopting multi-stage lens reduction, the angular magnification of the electron beam spot is correspondingly increased, and in order to ensure the paraxial relation in an actual lens system, the aperture of a diaphragm in an electron beam channel is generally smaller, so that the electron beam cannot effectively pass through a focusing system with large angular magnification, and the beam current of the electron beam bombarded on a target surface is reduced; therefore, it is difficult for a conventional multi-lens focusing system to ensure that an electron beam bombarded on a target surface has both large beam current and small beam spot, thereby affecting the focal spot size and power density of the generated X-ray.
The focusing system of the electron beam targeting X-ray source is mostly modified or referred to a magnetic lens for an electron microscope, when the beam spot of an electron beam on a target surface is small, the beam current is small, the power density of the generated X-ray is not high, and a clear image with high resolution and the field is difficult to obtain.
Disclosure of Invention
The invention provides a multi-lens combined focusing system device capable of realizing high reduction multiplying power, small aberration and high beam transmission efficiency, and particularly relates to an electron beam focusing device with high power density, aiming at the problem that a multi-lens system is difficult to guarantee that large beam current and small beam spot on a target surface are simultaneously considered.
The electron beam focusing device with high power density comprises a condenser lens module, an auxiliary condenser lens module and an objective lens module which are sequentially arranged along the emission direction of an electron beam;
the condenser lens module is used for forming a first magnetic field so as to enable the electron beams to form a cross point; the auxiliary condenser lens module is used for forming a second magnetic field so that the motion track of the electron beam is parallel to the optical axis to form a parallel beam, and the magnetic field intensity of the first magnetic field is larger than that of the second magnetic field; the objective lens module is used for forming a third magnetic field so that the electron beams are focused to the target plane.
Optionally, the high power density electron beam focusing apparatus further includes an electron beam passage tube passing through the condenser lens module, the auxiliary condenser lens module, and the objective lens module in this order.
Optionally, the condenser module further includes a first upper magnetic yoke and a first lower magnetic yoke fixedly connected to each other, and the auxiliary condenser further includes a second upper magnetic yoke and a second lower magnetic yoke fixedly connected to each other; the first lower yoke and the second upper yoke are integrally formed, and hereinafter, the yokes integrally formed by the first lower yoke and the second upper yoke are collectively referred to as a condenser-auxiliary condenser yoke; the condenser module and the auxiliary condenser module are integrated, so that materials are saved, and centering adjustment of the system is facilitated.
Optionally, a first annular cavity is arranged between the first upper magnetic yoke and the first lower magnetic yoke; a second annular cavity is arranged between the second upper magnetic yoke and the second lower magnetic yoke; the condenser lens module comprises a first magnetic field generating assembly, is arranged in the first annular cavity, is sleeved on the electron beam channel tube and is used for generating a first magnetic field; the auxiliary condenser comprises a second magnetic field generating assembly, is arranged in the second annular cavity, is sleeved on the electron beam channel tube and is used for generating a second magnetic field; the first magnetic field generating assembly and the second magnetic field generating assembly are independent magnetic field generating assemblies.
Optionally, the objective lens module comprises a third magnetic field generating assembly for generating a third magnetic field, and the third magnetic field generating assembly, the first magnetic field generating assembly and the second magnetic field generating assembly are independent magnetic field generating assemblies.
Optionally, the first magnetic field generating assembly comprises: the first pole shoe component is sleeved on the electron beam channel tube; a first coil assembly disposed about the first pole shoe assembly; the second magnetic field generating assembly includes: the second pole shoe component is sleeved on the electron beam channel tube; the second coil assembly is arranged on the periphery of the second pole shoe assembly; the first coil assembly and the second coil assembly are each independently adjustable to adjust respective coil assembly excitation currents to adjust the strength of the first magnetic field and the second magnetic field.
Optionally, the condenser lens assembly further comprises a condenser lens disposed at an intersection point of the horizontal center line of the first pole shoe assembly and the central axis of the electron beam passage tube; the auxiliary condenser lens assembly further comprises an auxiliary condenser lens, and the auxiliary condenser lens is arranged at the intersection point of the horizontal central line of the second pole shoe assembly and the central axis of the electron beam passage tube.
Optionally, the electron beam focusing device further comprises a transition module fixedly disposed between the auxiliary focusing lens module and the objective lens module.
Optionally, the electron beam focusing device further includes an objective lens diaphragm holder fixedly disposed at a lower end of the objective lens module, and the electron beam passage tube is fixedly connected to the objective lens diaphragm holder.
The invention has the advantages that:
(1) a high-power-density electron beam focusing device adopts a multi-lens combination mode of a condenser lens, an auxiliary condenser lens and an objective lens, wherein a condenser lens module is used for forming a first magnetic field to enable electron beams to be focused strongly and form cross points so as to enable the electron beams to achieve the reduction multiplying power required by a system, an auxiliary condenser lens module is used for forming a second magnetic field weaker than the first magnetic field to enable the electron beams to be focused weakly and enable the motion tracks of the electron beams to be parallel to an optical axis to form parallel beams so as to reduce the mutual repulsive force among the electron beams and further enable the divergence angles of the electron beams to be reduced, the electron beams in an electron beam channel tube are increased so as to achieve the small aberration of the system and the high transmission efficiency of beam current and achieve large beam current, the objective lens module is used for forming a third magnetic field so as to enable the electron beams to be focused on a target plane to obtain the modes of small beam current spots and electron beam cross-parallel-focusing, the beam current is ensured and the micro beam spot is realized at the same time.
(2) An objective lens module, a condenser lens module and an auxiliary condenser lens module can independently adjust respective coil component exciting currents, so that the magnetic field intensity of the objective lens module, the condenser lens module and the auxiliary condenser lens module is adjusted.
(3) The utility model provides a high power density's electron beam focusing device, condenser lens module and supplementary condenser lens module integrate two lenses, not only save material, still made things convenient for the centering adjustment of system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic diagram showing an electron optical path of the electron beam focusing apparatus of the present embodiment;
fig. 2(a) shows a schematic view of the electron beam cross-parallel-focusing mode operation of the present embodiment, (b) shows a schematic view of the electron beam cross-focusing mode operation without an auxiliary condenser;
FIG. 3 is a view showing an overall configuration of an electron beam focusing apparatus of the present embodiment;
fig. 4 is a schematic structural view showing a condenser module and an auxiliary condenser module of the present embodiment;
fig. 5 is a schematic structural view showing an objective lens module of the present embodiment;
wherein the reference numerals are:
10-an electron gun; 20-a condenser module; 30-an auxiliary condenser module; 40-an objective lens module; 50-a target material; 60-objective diaphragm module; 101-a first upper yoke; 102-condenser-auxiliary condenser yoke; 103-a second lower yoke; 104-a first pole shoe member; 1041-condenser upper pole shoe; 1042 — condenser lower pole piece; 1043-condenser pole shoe magnetism isolating ring; 1044 — condenser position; 105-a first coil assembly; 1051-condenser coil; 1052-condenser coil bobbin; 106-a concentrator mirror seal ring; 107-a second pole shoe member; 1071 — pole shoe on auxiliary condenser; 1072 — lower pole shoe of auxiliary condenser; 1073-auxiliary collecting lens pole shoe magnetism isolating ring; 1074 — auxiliary condenser position; 108-a second coil assembly; 1081-auxiliary condenser coil; 1082-auxiliary condenser coil armature; 109-auxiliary collector seal ring; 201-a transition section module; 202-an on-objective module; 203-lower objective module; 204-objective lens coil assembly; 2041 — objective coil; 2042-objective lens bobbin; 205-objective lens position; 501-electron beam passage tube; 601-objective diaphragm holder.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, an embodiment of the present invention provides an electron beam focusing apparatus, including: a condenser module 20, an auxiliary condenser module 30, an objective module 40 and an objective diaphragm module 60 sequentially arranged along an electron beam emission direction;
the condenser lens module 20 is used to form a first magnetic field to make the electron beam form a cross point;
the auxiliary condenser lens module 30 is configured to form a second magnetic field, so that a motion trajectory of the electron beam is parallel to the optical axis to form a parallel beam, and the first magnetic field has a magnetic field intensity greater than that of the second magnetic field;
the objective module 40 is used to generate a third magnetic field to focus the electron beam to the target plane through the objective stop module 60.
The electron gun 10 emits an electron beam and sequentially passes through the condenser module 20, the auxiliary condenser module 30, the objective module 40 and the objective diaphragm module 60, as shown in fig. 2(a), the condenser module 20 is configured to form a first magnetic field to strongly focus the electron beam and form a cross point, so that the electron beam achieves a reduction ratio required by the system, the auxiliary condenser module 30 is configured to form a second magnetic field weaker than the first magnetic field to weakly focus the electron beam, so that a motion trajectory of the electron beam is parallel to an optical axis to form a parallel beam, so that a mutual repulsion force between the electron beams is reduced, so that a divergence angle of the electron beam is reduced, a small aberration of the system and a high beam transfer efficiency of the beam are achieved, a large beam is achieved, the objective module 40 is configured to form a third magnetic field, so that the electron beam is focused on a plane of the target 50 through the objective diaphragm module 60, a small beam spot is obtained, and a micro beam spot is achieved while ensuring the beam spot, the electron beam of the microbeam spot produces an X-ray beam by bombarding the target 50. Without the second magnetic field formed by the auxiliary condenser 30, as shown in fig. 2(b), under the same reduction factor, the divergence angle of the electron beam is too large when the electron beam passes through the condenser module 20 to form the intersection, which exceeds the acceptance angle of the objective diaphragm module 60, thereby reducing the transmission efficiency of the focusing system to the electron beam and reducing the beam reaching the target surface.
The electron beam focusing device has an overall cylindrical structure, as shown in fig. 3, and includes an electron beam passage tube 501, a condenser module 20, an auxiliary condenser module 30, a transition section module 201, an objective lens module 40, and an objective lens diaphragm holder 601.
In order to avoid the electrons from flying around in the entire electron beam focusing apparatus, the electron beam passage tube 501 and the objective lens stop 601 are used to confine the electrons to the paraxial region of the system.
The electron beam passage tube 501 is integrally located on the central axis of the electron beam focusing device, and is a hollow tube made of hard aluminum or copper material, the upper end of the electron beam passage tube 501 is connected with the electron gun 10, and after sequentially passing through the condenser lens module 20, the auxiliary condenser lens module 30, the transition section module 201 and the objective lens module 40, the lower end is connected with the objective lens diaphragm seat 601. The fixedly connected condenser lens module 20, the auxiliary condenser lens module 30, the transition section module 201, the objective lens module 40 and the objective lens diaphragm seat 601 are all connected through screws.
The transition section module 201 is a cylinder with a hollow inner part, and the central axis of the cylinder is the same as that of the electron beam passage tube 501.
The condenser module 20 and the auxiliary condenser module 30 are shown in fig. 4, and include a first upper yoke 101, a condenser-auxiliary condenser yoke 102, a second lower yoke 103, a first pole piece assembly 104, a first coil assembly 105, a condenser seal ring 106, a second pole piece assembly 107, a second coil assembly 108, and an auxiliary condenser seal ring 109;
the upper and lower end surfaces of the condenser-auxiliary condenser yoke 102 are both provided with annular grooves;
an annular groove is formed in the lower end face of the first upper magnetic yoke 101, the annular groove is fixedly buckled with the upper end face of the condenser-auxiliary condenser magnetic yoke 102, and the condenser sealing ring 106 is used for sealing and isolating the annular groove to form a first annular cavity, and the central axes of the first upper magnetic yoke 101 and the condenser-auxiliary condenser magnetic yoke 102 are the same as the central axis of the electron beam channel tube 501; the first magnetic field generating assembly comprises a first pole shoe assembly 104 and a first coil assembly 105, the first pole shoe assembly 104 comprises a condenser upper pole shoe 1041 and a condenser lower pole shoe 1042, which are assembled into a whole through a pole shoe magnetism isolating ring 1043 and are the same with the central axis of the electron beam passage tube 501; the horizontal center line of the first pole shoe member 104 is perpendicular to the central axis of the electron beam passage tube 501, and the intersection point position is the condenser position 1044; the first coil assembly 105 is a circular ring, and comprises a condenser coil 1051 and a condenser bobbin 1052, and is installed in a first annular cavity formed by the first upper yoke 101 and the condenser-auxiliary condenser yoke 102 through the bobbin, and is at the periphery of the first pole piece assembly 104; the first magnetic field generating assembly is used for forming a first magnetic field so as to enable the electron beam to be focused strongly and form a cross point, and the electron beam can achieve the reduction magnification required by the system;
an annular groove is formed in the upper end face of the second lower magnetic yoke 103, the annular groove is buckled and fixed with the lower end face of the condenser-auxiliary condenser magnetic yoke 102, the condenser-auxiliary condenser magnetic yoke is sealed and isolated by an auxiliary condenser sealing ring 109 to form a second annular cavity, and the central axis of the second lower magnetic yoke 103 is the same as that of the electron beam passage tube 501; the first magnetic field generation assembly comprises a second pole shoe assembly 107 and a second coil assembly 108, the second pole shoe assembly 107 comprises an auxiliary condenser upper pole shoe 1071 and an auxiliary condenser lower pole shoe 1072, and the pole shoe magnetism isolating ring 1073 is assembled into a whole and is the same as the central axis of the electron beam channel tube 501; the horizontal central line of the second pole shoe assembly 107 is perpendicular to the central axis of the electron beam passage tube 501, and the intersection point position is an auxiliary condenser position 1074; the second coil assembly 108 is a circular ring, comprises an auxiliary condenser coil 1081 and an auxiliary condenser bobbin 1082, is mounted in a second annular cavity formed by the second lower yoke 103 and the condenser-auxiliary condenser yoke 102 through a bobbin, and is at the periphery of the second pole piece assembly 107; the second magnetic field generating assembly is used for forming a second magnetic field so as to enable the electron beams to be weakly focused, the motion tracks of the electron beams to be parallel to the optical axis to form parallel beams, the mutual repulsive force between the electron beams is reduced, the divergence angle of the electron beams is reduced, the electron beams in the electron beam channel tube 501 are increased, the small aberration of the system and the high beam transmission efficiency are realized, and the large beam is realized;
the first magnetic field generating assembly and the second magnetic field generating assembly can be independent magnetic field generating assemblies, and the excitation currents of the coil assemblies can be independently adjusted, so that the magnetic field strengths of the first magnetic field and the second magnetic field are adjusted.
The upper objective lens module 202 and the lower objective lens module 203 are buckled and fixed, and an objective lens coil assembly 204 is arranged in the hollow space; the axisymmetric centers of the upper objective lens module 202 and the lower objective lens module 203 are the same as the central axis of the electron beam passage tube 501, and a passage is opened on the axisymmetric center for the electron beam to pass through;
the objective lens coil assembly 204 is annular and is arranged above the objective lens lower module 203, and the magnetic field intensity of the third magnetic field is adjusted by adjusting the exciting current of the objective lens coil assembly 204; the horizontal direction of the upper objective lens block 202 and the lower objective lens block 203 forms a gap, and the intersection point of the central position of the gap and the axis is the objective lens position 205.
The lower end of the objective lens module 40 is sleeved with an objective lens diaphragm seat 601, the objective lens diaphragm seat is integrally of a circular ring structure, and a hole in the center of the circular ring is an objective lens diaphragm hole.
The parameters of the electron beam focusing device with high power density are described in detail below with reference to fig. 1 to 5, and specifically, the parameters of the electron beam focusing device may include: initial parameter and performance index, the structural parameter and the electrical parameter of the objective lens module according to initial parameter setting to and condenser lens module and supplementary condenser lens module's position, structure and electrical parameter, specific:
initial parameters of the electron beam focusing device with high power density comprise parameters of an electron source and parameters of a target;
the parameters of the electron source comprise electron beam energy, electron beam energy divergence, the position and the diameter of a transmitting lamp tip, the temperature of the lamp tip, theoretical brightness, source beam current, spatial distribution, cross spot diameter and an emergent angle; parameters of the target include the type and location of the target, and two types of targets are commonly used: the transmission type is easy to realize high geometric magnification, and is commonly used for high-resolution detection; the reflective type has the characteristic of high power, but has heel effect and smaller resolution, and the invention is illustrated by taking a transmission target as an example.
160kV lanthanum hexaboride is selected as an electron emission source of an electron beam targeting high-power-density micro-focal spot X-ray source focusing device, and parameters are shown in Table 1.
Table 1 shows the parameters of the electron emission source of the present invention
The parameters of the target are shown in Table 2.
Table 2 shows the parameters of the target of the invention
| Type of target | Transmission target |
| Position of target surface | The lower surface of the pole shoe is close to the lower surface of the objective lens |
2) The performance indexes of the electron beam focusing device are the beam current and the beam spot diameter of the electron beam on the target surface, and the parameters are listed in Table 3;
the beam current at the target surface is represented as
Wherein beta is the brightness of the electron gun, m is the reduction ratio of the system, m is more than 0 and less than 1, d0The diameter of the cross spot of the electron source, and alpha is the aperture angle of the electron beam;
the diameter of the beam spot of the electron beam at the target surface can be approximately expressed as
In the formula (I), the compound is shown in the specification,
is the diameter of the spherical aberration diffuse spot,
is the chromatic aberration, the diameter of the speckles CsAnd CcThe spherical aberration coefficient and the chromatic aberration coefficient of the objective lens are respectively; e is the energy of the electron, and Δ E is the energy spread of the electron.
Under the given electron source parameters, a large beam current and a small beam current are needed to obtain a focal spot with high power density, but the large beam current inevitably brings a large target surface incidence angle, and the beam current is also large, so the large beam current and the small beam current are contradictory to each other and need to be comprehensively considered; the invention has higher voltage ratio, so that chromatic aberration can be ignored, and in order to obtain the micro-beam spot, an objective lens with a low spherical aberration coefficient needs to be designed, and the reduction magnification and the incident beam half angle at the target surface are comprehensively considered.
Table 3 shows the beam current and diameter of the electron beam on the target surface according to the invention
| Electron beam current | ≥50μA |
| Diameter of beam spot | ≤1μm |
Setting structural parameters and electrical parameters of the objective lens module according to initial conditions, specifically:
1) setting the position and structural parameters of the objective lens module;
the structural parameters of the objective lens module comprise structural parameters of upper and lower pole shoes of the objective lens and structural parameters of upper and lower magnetic yokes of the objective lens;
the structural parameters of the upper and lower pole shoes of the objective lens comprise: the material of the upper and lower pole shoes of the objective lens, the working distance of the objective lens, the aperture D1 of the upper pole shoe of the objective lens, the aperture D2 of the lower pole shoe of the objective lens and the gap S between the upper and lower pole shoes;
the structural parameters of the upper and lower magnetic yokes of the objective lens comprise: the size of an objective lens magnetic yoke, the outer diameter and the angle of an objective lens upper pole shoe, the thickness of the objective lens upper pole shoe, the outer diameter and the angle of an objective lens lower pole shoe, the thickness of the objective lens lower pole shoe and the shape and the size of an objective lens coil frame;
the position of the objective lens is the center of the gap between the upper pole shoe and the lower pole shoe of the objective lens;
according to the parameters of the electron source and the parameters of the target, the imaging conditions of the objective lens module are designed, and the structural design of the objective lens module meets the following requirements for obtaining the performance index of the focusing system device: according to the principle that the longer the focal length is, the larger the working distance is, the larger the aberration of the focusing system device is, and the zoom ratio of the focusing system device is reduced, in order to reduce the diameter of an electron beam spot at the incident position of a target surface, the distance between the lower end surface of a lower pole shoe of an objective lens and the target surface, namely the working distance of the objective lens, is shortened as much as possible, and the working distance is preferably 0mm in combination with the assembly of an actual focusing system device; in order to limit stray electrons, the diameter of the aperture in the middle of the objective diaphragm holder is in the range of 0.2mm to 1.5mm, preferably 1 mm. The larger the aperture D1 of the objective lens upper pole piece and the aperture D2 of the objective lens lower pole piece, the easier the optical axis paraxial condition is satisfied, the higher the objective lens stability and the smaller the aberration, but the yoke of the objective lens is easily saturated, and the aperture D1 and the aperture D2 are in the range of 4mm to 30mm, preferably 12mm, in general. The aberration becomes smaller as the gap S between the upper pole piece and the lower pole piece of the objective lens is smaller, but is too small and easily saturated, and the gap S ranges from 1mm to 20mm, preferably 5.5 mm. Meanwhile, in order to avoid magnetic circuit saturation, the length, thickness and the like of the magnetic yoke are optimized, and important parameters are shown in table 4.
Table 4 shows key parameters of the objective lens module of the present invention
| Pole shoe material | Electrician pure iron DT4C |
| Working distance of objective lens | 0mm |
| Objective lens upper pole shoe aperture D1 | 12mm |
| Aperture D2 of objective lens lower pole piece | 12mm |
| Upper and lower pole shoe gap S of objective lens | 5.5mm |
| Thickness of lower pole shoe of objective lens | 2.865mm |
| Excitation of objective coil assembly | 4297A-t |
| Position of the objective lens | 294.5mm |
| Aperture diameter of objective lens | 1mm |
2) Setting electrical parameters of the objective lens module;
the electrical parameters of the objective lens are the excitation a-t of the objective lens coil module. According to the design, after the space distribution of the objective lens magnetic field is obtained by combining the structural parameter modeling numerical calculation of the objective lens module, the electron source, the objective lens and the target are arranged together to form an objective lens focusing system, the motion track of the electron beam under the action of the magnetic field is calculated, and the excitation of the objective lens is adjusted to control the electron beam to be focused on the target plane according to the selected working distance. The beam current on the target was calculated to be 80 μ A with a beam spot of 1 μm at 4297A-t objective excitation.
The position, structure and electrical parameters of the condenser lens module and the auxiliary condenser lens module are set, so that the required reduction magnification of the system and the cross-parallel mode of the electron beam are realized, and the method is specific:
1) setting the position and structural parameters of a condenser module and an auxiliary condenser module to realize the reduction ratio required by the system;
the structure parameters of the condenser module and the auxiliary condenser module comprise the structure parameters of a first upper pole shoe, a second upper pole shoe, a first upper magnetic yoke, a condenser-auxiliary condenser magnetic yoke and a second lower magnetic yoke;
the structural parameters of the first upper and lower pole shoes comprise the materials of the first upper and lower pole shoes, the aperture D11 of the first upper pole shoe, the aperture D21 of the first lower pole shoe and the gap S1 of the first upper and lower pole shoe;
the structural parameters of the second upper and lower pole shoes comprise the material of the second upper and lower pole shoes, the aperture D12 of the second upper pole shoe, the aperture D22 of the second lower pole shoe and the gap S2 of the second upper and lower pole shoe;
the structural parameters of the first upper magnetic yoke, the condenser-auxiliary condenser magnetic yoke and the second lower magnetic yoke comprise the material of each magnetic yoke, a magnetism isolating assembly part, the structural size of the first coil and the structural size of the second coil;
the position of the condenser and the position of the auxiliary condenser are respectively the center of the gap between the first upper pole shoe and the second lower pole shoe;
the important parameters of the concentrator and auxiliary concentrator modules are listed in table 5.
Table 5 shows the important parameters of the condenser-auxiliary condenser module of the present invention
| Material for pole shoe and magnetic yoke of condenser | Electrician pure iron DT4C |
| First upper pole shoe aperture D11 | 12mm |
| First lower poleBoot aperture D21 | 12mm |
| First Upper and lower Pole shoe gap S1 | 6mm |
| Condenser position | 80mm |
| Excitation of the first coil assembly | 2554A-t |
| Second pole shoe and magnetic yoke material | Electrician pure iron DT4C |
| Second upper pole shoe aperture D12 | 12mm |
| Second lower pole piece aperture D22 | 12mm |
| Second Upper and lower pole piece gap S2 | 6mm |
| Auxiliary condenser position | 152mm |
| Excitation of the second coil assembly | 1264A-t |
| Magnetic isolation assembly | Copper/duralumin alloy |
2) Optimizing the electrical parameters of the condenser lens module and the auxiliary condenser lens module to realize the cross-parallel mode of the electron beams;
the electrical parameter of the condenser lens module is the excitation A-t of the first coil assembly, and the electrical parameter of the auxiliary condenser lens module is the excitation A-t of the second coil assembly; it is known from theory that the zoom ratio of the system can be improved by increasing the object distance between the condenser and the auxiliary condenser, but the object distance should not be too large to ensure the beam current on the target. And then, according to the parameters of the auxiliary condenser module, a second magnetic field is calculated by using a second order finite element, excitation of a second coil is controlled, and after the electron beam passes through the second magnetic field, the motion track is parallel to the optical axis to form a parallel beam.
A cross-parallel-focusing system formed by combining a condenser lens module, an auxiliary condenser lens module and an objective lens module is shown in figures 1-5, electron source parameters, positions of lenses, excitation and the like are combined, numerical simulation calculation is carried out, and finally, the beam current of 80 muA, the beam spot of 0.9μm and the power density of 1W/mum are obtained under the acceleration voltage of 160kV2Electron beam of the microbeam.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.
Claims (4)
1. An electron beam focusing device with high power density is an electron beam targeting X-ray source focusing system, and comprises an electron gun (10), a condenser lens module (20), an objective lens module (40), an objective lens diaphragm module (60) and a target (50);
a condenser lens module (20), an auxiliary condenser lens module (30) and an objective lens module (40) are sequentially arranged along the electron beam emission direction of the electron gun (10); an electron beam passage tube sequentially passing through the condenser module (20), the auxiliary condenser module (30) and the objective lens module (40);
the condenser lens module (20) is used for forming a first magnetic field so as to enable the electron beams to form a cross point;
the objective lens module (40) forms a third magnetic field by using a third magnetic field generating assembly to focus the electron beam to the target plane;
the method is characterized in that:
the condenser module (20) further comprises: the magnetic field generating device comprises a first magnetic field generating assembly, a first upper magnetic yoke (101) and a first lower magnetic yoke which are fixedly connected; the first magnetic field generating assembly comprises a first pole shoe assembly (104) and a first coil assembly (105); a first pole shoe member (104) is sleeved on the electron beam channel tube; a first coil assembly (105) is disposed about the first pole shoe assembly (104);
the aperture of a first upper pole shoe and the aperture of a first lower pole shoe of the first pole shoe component (104) are both 12mm, and the pole shoe distance between the aperture of the first upper pole shoe and the aperture of the first lower pole shoe is 6 mm;
the auxiliary condenser module (30) further comprises: a second magnetic field generation assembly, a second upper magnetic yoke and a second lower magnetic yoke (103) which are fixedly connected; the second magnetic field generating assembly comprises a second pole shoe assembly (107) and a second coil assembly (108); a second pole shoe component (107) is sleeved on the electron beam channel tube; a second coil assembly (108) is arranged at the periphery of the second pole shoe assembly (107);
the aperture of a second upper pole shoe and the aperture of a second lower pole shoe of the second pole shoe component (107) are both 12mm, and the pole shoe distance between the aperture of the second upper pole shoe and the aperture of the second lower pole shoe is 6 mm;
a first annular cavity is arranged between the first upper magnetic yoke (101) and the first lower magnetic yoke; the first magnetic field generating assembly is arranged in the first annular cavity and sleeved on the electron beam channel tube;
a second annular cavity is arranged between the second upper magnetic yoke and the second lower magnetic yoke (103); the second magnetic field generating assembly is arranged in the second annular cavity and sleeved on the electron beam channel tube;
the first magnetic field generating assembly and the second magnetic field generating assembly are mutually independent magnetic field generating assemblies;
the auxiliary condenser lens module (30) is used for forming a second magnetic field so that the motion track of the electron beam is parallel to the optical axis to form a parallel beam;
the first magnetic field is greater than the magnetic field strength of the second magnetic field;
the first lower magnetic yoke and the second upper magnetic yoke are integrally formed;
the condenser lens module (20) is arranged at a position 80mm away from the emission point of the electron beam, and the auxiliary condenser lens module (30) is arranged at a position 152mm away from the emission point of the electron beam;
the aperture range of the pole shoe of the objective lens module (40) is 4 mm-30 mm, and the range of the pole shoe space is 1 mm-20 mm.
2. The focusing device according to claim 1, wherein the third magnetic field generating assembly, the first magnetic field generating assembly and the second magnetic field generating assembly are independent magnetic field generating assemblies, respectively.
3. The focusing arrangement according to claim 1,
the condenser lens module (20) further comprises a condenser lens, and the condenser lens is arranged at the intersection point of the horizontal central line of the first pole shoe component and the central axis of the electron beam passage tube;
the auxiliary condenser module (30) further comprises an auxiliary condenser, and the auxiliary condenser is arranged at the intersection point of the horizontal central line of the second pole shoe assembly and the central axis of the electron beam passage tube.
4. An image forming apparatus, characterized by comprising:
electron beam emitting means for emitting an electron beam;
the high power density electron beam focusing device of any one of claims 1-3;
and the imaging device is used for imaging by utilizing the electron beams processed by the electron beam focusing device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811281545.9A CN109585244B (en) | 2018-10-23 | 2018-10-23 | High power density electron beam focusing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811281545.9A CN109585244B (en) | 2018-10-23 | 2018-10-23 | High power density electron beam focusing device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109585244A CN109585244A (en) | 2019-04-05 |
| CN109585244B true CN109585244B (en) | 2021-09-14 |
Family
ID=65920845
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811281545.9A Active CN109585244B (en) | 2018-10-23 | 2018-10-23 | High power density electron beam focusing device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109585244B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111413727B (en) * | 2020-04-15 | 2021-12-28 | 中国科学院电工研究所 | Electron beam divergence angle measuring device and preparation method and measuring method thereof |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5124556A (en) * | 1989-10-20 | 1992-06-23 | Jeol Ltd. | Charged particle beam apparatus |
| US6753533B2 (en) * | 2002-11-04 | 2004-06-22 | Jeol Ltd. | Electron beam apparatus and method of controlling same |
| CN1971834A (en) * | 2005-11-07 | 2007-05-30 | 科美特有限公司 | Nanofocus X-ray tube |
| US7705298B2 (en) * | 2007-10-26 | 2010-04-27 | Hermes Microvision, Inc. (Taiwan) | System and method to determine focus parameters during an electron beam inspection |
| TW201417134A (en) * | 2012-10-16 | 2014-05-01 | Integrated Circuit Testing | Octopole device and method for spot size improvement |
| CN105047509A (en) * | 2015-07-24 | 2015-11-11 | 中国科学院电工研究所 | Focusing device for large-beam-current electronic beam targeting X-ray source with micro beams |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5952048B2 (en) * | 2012-03-23 | 2016-07-13 | 株式会社日立ハイテクサイエンス | Ion beam equipment |
| CZ2016300A3 (en) * | 2016-05-21 | 2017-07-12 | Tescan Brno, S.R.O. | A scanning electron microscope and the method of its operation |
-
2018
- 2018-10-23 CN CN201811281545.9A patent/CN109585244B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5124556A (en) * | 1989-10-20 | 1992-06-23 | Jeol Ltd. | Charged particle beam apparatus |
| US6753533B2 (en) * | 2002-11-04 | 2004-06-22 | Jeol Ltd. | Electron beam apparatus and method of controlling same |
| CN1971834A (en) * | 2005-11-07 | 2007-05-30 | 科美特有限公司 | Nanofocus X-ray tube |
| US7705298B2 (en) * | 2007-10-26 | 2010-04-27 | Hermes Microvision, Inc. (Taiwan) | System and method to determine focus parameters during an electron beam inspection |
| TW201417134A (en) * | 2012-10-16 | 2014-05-01 | Integrated Circuit Testing | Octopole device and method for spot size improvement |
| CN105047509A (en) * | 2015-07-24 | 2015-11-11 | 中国科学院电工研究所 | Focusing device for large-beam-current electronic beam targeting X-ray source with micro beams |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109585244A (en) | 2019-04-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101988538B1 (en) | X-ray generating apparatus | |
| TWI435362B (en) | Charged particle apparatus | |
| US7372195B2 (en) | Electron beam source having an extraction electrode provided with a magnetic disk element | |
| KR20140109809A (en) | X-ray generation tube, x-ray generation device including the x-ray generation tube, x-ray imaging system | |
| CN109585244B (en) | High power density electron beam focusing device | |
| EP4080541A2 (en) | Method and system for liquid cooling isolated x-ray transmission target | |
| EP2954549B1 (en) | Method and apparatus for generation of a uniform-profile particle beam | |
| CN105140088B (en) | The focusing arrangement and its application method of big beam deflection target practice X-ray source with microbeam | |
| GB665094A (en) | Improvements relating to the reduction of primary spherical aberration in magnetic electron lenses | |
| JPWO2013065399A1 (en) | Scanning electron microscope | |
| US4468563A (en) | Electron lens | |
| GB865050A (en) | Improvements in or relating to x-ray shadow microscopes with adjustable optical focussing | |
| US8164066B2 (en) | Magnetic lens, method for focusing charged particles and charged particle energy analyzer | |
| US4097739A (en) | Beam deflection and focusing system for a scanning corpuscular-beam microscope | |
| CN218069774U (en) | Electromagnetic lens coil cooling system for scanning electron microscope | |
| US3188465A (en) | Two stage electron beam magnification device comprising plural adjustable magnetic lens system | |
| CN218918781U (en) | Scanning electron microscope | |
| US3731094A (en) | Electron beam apparatus with means for generating a rotation-symmetrical magnetic field | |
| JP2002056794A (en) | Objective lens for electron microscope | |
| US11864300B2 (en) | X-ray source with liquid cooled source coils | |
| CN218918782U (en) | Scanning electron microscope | |
| CN115394619A (en) | Method for enabling open type X-ray tube to have multiple working modes | |
| Tsuno et al. | Design of an objective lens with a minimum chromatic aberration coefficient | |
| JP3280187B2 (en) | Scanning electron microscope | |
| Al-Ghuraibawi | Calculations of Gabor Lens Having Two Glaser Field Distributions |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |