Particle energy analysis equipment

Abstract

The utility model discloses particle energy analysis equipment, which comprises detection equipment, a lens system and rotating equipment, and is characterized in that the detection equipment is provided with an inlet slit allowing particles to enter; the lens system is positioned between the charged particle sample and the entrance slit, is used for forming a particle beam of charged particles and transmitting the particle beam, and is provided with a straight optical axis; and a rotating device disposed at the lens system for causing the particle beam to rotate before the particle beam enters the entrance slit. The magnetic field rotation technology is adopted in the lens system, on one hand, the receiving angle can be amplified, the measurement efficiency is improved, on the other hand, the electrostatic field of the lens system is axially symmetric all the time, the particle flying process is axially symmetric, and the distortion problem can be effectively solved.

Description

Technical Field

[0001] The utility model relates to the technical field of energy analyzers, in particular to a particle energy analysis device. Background Art

[0002] A particle energy analysis device is a device that can analyze the energy, starting direction, and starting position of charged particles emitted from a particle emission sample. The structure of a more common particle energy analysis device in the prior art is as follows: Figure 2 As shown, it is a hemispherical deflection type particle energy analyzer disclosed in patent CN104040681B, which is composed of a charged particle sample 1, an electrostatic lens system 2, an entrance slit 4, and a detection device 3. The electrostatic lens system 2 includes a plurality of lenses L1-L4, which are arranged symmetrically about the optical axis 10, and a first deflector 11a and a second deflector 11b. The detection device 3 is introduced by taking a hemispherical analyzer as an example, and the hemispherical analyzer includes a base plate 6, two concentric hemispheres (inner hemisphere 5a and outer hemisphere 5b) mounted thereon, and a particle detector 7. An electrostatic field is applied between the two concentric hemispheres, and particles of different energies have different bending radii in this electrostatic field, so that different energy resolution can be achieved.

[0003] The lens system 2 has two different modes, namely, imaging mode and angle resolution (angle) mode. In the imaging mode, there is a point-to-point correspondence between the emission point (x, y) and the position (x, y) in the plane where the entrance slit 4 is located; in the angle mode, there is an angle-point correspondence between the emission point exit angle (θx, θy) and the position (x, y) in the plane where the entrance slit 4 is located. Because of the existence of the entrance slit 4, only part of the particles in the plane (x, y) can enter the detection device 3, corresponding to part of the image (x, y≈0) or part of the angle (θx, θy≈0) at the sample point being detected. Specifically, in the angle mode, the detectable angle range is usually about 0.3°. Therefore, the existing design cannot measure the entire (θx, θy) two-dimensional space, and cannot obtain complete data for the entire (θx, θy) two-dimensional space.

[0004] In order to solve the above-mentioned shortcomings, the prior art proposes to add a deflector to the lens system or combine the lens axis deflection, for example:

[0005] refer to Figure 1 In the structure shown in 1a, CN104040681B adds a two-stage deflector, namely a first deflector 11a and a second deflector 11b, to the lens system 2. With the two-stage deflector, particles with different θy (θy≠0) can be deflected to the entrance 4 and enter the measurement area 3.

[0006] refer to Figure 1In the structure shown in 1b, JP2017224609A adds a deflector 11 in the lens system 2, and the lens system 2 can be offset as a whole, so that the lens axis deviates from the original optical axis 10; thereby, particles with different θy (θy≠0) can be deflected to the entrance 4 and enter the measurement area 3.

[0007] refer to Figure 1 In the structure shown in 1c, CN111739782A uses a deflectometer 11 in the lens system 2. At the same time, the lens systems before and after the deflectometer 11 have expanded their functions, so that when the particles pass through the deflectometer 11, they are distributed as images (x, y), and the lens system behind the deflectometer 11 forms an angle distribution (θx, θy) on the plane of the entrance slit 4. According to the characteristics of the lens system, the image (x, y) and the angle distribution (θx, θy) satisfy the Fourier transform, so the image (x, y) is offset at the deflectometer 11 to achieve the offset of the angle distribution (θx, θy), and then particles with different θy (θy≠0) can be deflected to the entrance slit 4 and enter the detection device 3.

[0008] Although the above technical solutions can make particles of different θy enter the detection device 3 through the deflection technology, the above methods still have shortcomings:

[0009] (1) When using deflection, the electrostatic field of the lens system is not axisymmetric, resulting in significant edge distortion.

[0010] Taking the above three patents as an example, when deflecting, the electrostatic field of the lens system is actually non-axisymmetric; this non-axisymmetric structure causes data distortion when θy is large, which in turn leads to inaccurate angle resolution and (θx, θy) two-dimensional data restoration.

[0011] (2) When using deflection, the angle range within which the lens system can be deflected is limited.

[0012] Through two-stage deflection or "deflection + lens shift" and other technologies, the off-axis particle beam is twisted by passing it through a certain field. This leads to a certain angular upper limit in the twisting process, which cannot be expanded. The current common angular upper limit is ±15°. Utility Model Content

[0013] In order to solve the deficiencies in the prior art, the present application proposes a particle energy analysis device, which adopts magnetic field rotation technology in the lens system. On the one hand, it can amplify the receiving angle and improve the measurement efficiency. On the other hand, the electrostatic field of the lens system is always axially symmetrical, and the particle flight process is also axially symmetrical, which can effectively solve the distortion problem.

[0014] The technical solution adopted by the utility model is as follows:

[0015] A particle energy analysis device, characterized in that it includes: a detection device and a lens system; the lens system has a straight optical axis; a rotating device is arranged in the lens system; the rotating device generates an adjustable magnetic field, and the particles change their rotation angle under the action of the magnetic field generated by the rotating device; the direction of the magnetic field is parallel to the optical axis on the optical axis; the rotating device causes the charged particles passing through to rotate around the optical axis.

[0016] Furthermore, the lens system includes a plurality of lenses, which are arranged in sequence along the optical axis, and each lens stage is symmetrically distributed about the optical axis.

[0017] Furthermore, a rotating device is provided on one or more lenses in the lens system.

[0018] Furthermore, the signal of the rotating device is connected to the control unit, and the rotation angle of the particles is controlled by regulating the magnetic field generated by the rotating device.

[0019] Furthermore, the rotating device comprises at least one magnetic coil.

[0020] Furthermore, the lens closest to the sample is an active lens, and a rotating device is arranged on the lens behind the active lens.

[0021] Furthermore, the detection device includes a particle detector, which is used to detect the position of the charged particle, and the position includes at least one parameter.

[0022] Furthermore, the particle detector is constructed to determine the energy of the charged particles and the starting direction or starting position of the particles.

[0023] Beneficial effects of the utility model:

[0024] (1) The utility model adopts magnetic field rotation technology. The electrostatic field of the lens system is always axially symmetrical, and the particle flight process is also axially symmetrical, which can effectively solve the distortion problem.

[0025] (2) The utility model adopts magnetic field rotation technology. During the flight, the particles only rotate around the optical axis without deviation, so the receiving angle can be further enlarged, greatly improving the measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of an existing hemispherical deflection type particle energy analyzer, wherein 1a is a lens system with an additional secondary deflector, 1b is a lens system with an additional deflector and deflection, and 1c is an extended lens system that uses a deflector and performs functions before and after the deflector.

[0027] Figure 2 yes Figure 1 The diagram shows the particle distribution at the entrance and the same exit angle of the hemispherical deflection type particle energy analyzer. 2a is a schematic diagram of the single-layer entrance slit arrangement, and 2b is a schematic diagram of the multi-layer entrance slit arrangement.

[0028] Figure 3 The utility model is a schematic diagram of the structure of a particle energy analysis device provided by the utility model.

[0029] Figure 4 The utility model is a schematic diagram of the structure of a particle energy analysis device provided by the utility model.

[0030] Figure 5 It is a schematic diagram of various arrangements of rotating equipment, wherein 5a, 5b, and 5c correspond to schematic diagrams of 1, 2, and 3 coils arranged in parallel, respectively.

[0031] Figure 6 Schematic diagram of the principle of the utility model, where 6a is the rotation angle of the entrance slit around the z axis Schematic diagram, 6b is a schematic diagram of the offset of the origin of the angular space of the sample to be tested relative to the center of the slit.

[0032] In the figure, 1. charged particle sample, 2. lens system, 2a. active lens, 2b. passive lens, L1-L7 are all lenses, 3. detection equipment, 4. entrance slit, 5a. inner hemisphere, 5b. outer hemisphere, 6. bottom plate, 7. particle detector, 8. rotating equipment, 10. optical axis, 11. deflectometer. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0034] Example 1

[0035] The utility model proposes a particle energy analysis device, the structure of which is as follows: Figure 3 As shown, it includes: an electrostatic lens system 2, a detection device 3 and a rotation device 8. More specifically,

[0036] The electrostatic lens system 2 includes a multi-stage lens, which is arranged in sequence along the optical axis 10. Each stage of the lens is symmetrically distributed about the optical axis 10, such as the lenses L1-L4 arranged in sequence in the figure. A charged particle sample 1 is placed at one end of the electrostatic lens system 2, and the other end is opposite to the entrance end of the hemispherical energy analyzer. Charged particle sample 1

[0037] The detection device 3 is introduced by taking a hemispherical energy analyzer as an example. The hemispherical energy analyzer includes a bottom plate 6, an entrance slit 4, a hemispherical structure and a particle detector 7. The hemispherical structure is arranged on the bottom plate 6. The hemispherical structure is composed of two concentric hemispheres, namely an inner hemisphere 5a and an outer hemisphere 5b. An electrostatic field is applied between the two concentric hemispheres. Since particles of different energies have different bending radii in the electrostatic field, energy resolution of particles of different energies is achieved. An entrance slit 4 is arranged at the entrance end of the hemispherical structure. A particle detector 7 is arranged at the exit end of the hemispherical energy analyzer.

[0038] A rotating device 8 is provided at any one or more lenses of the electrostatic lens system 2. The rotating device 8 is used to generate a magnetic field arranged along the optical axis 10 (the z axis in the figure). After passing through the magnetic field, the particles in the electrostatic lens system 2 can rotate around the optical axis 10; the angle of particle rotation satisfies the following formula:

[0039]

[0040] in, is the rotation angle of the particle, Bz is the magnetic field component of the lens axis, integrated on the optical axis; U* is the relativistic energy of the electron; e is the electron charge; m is the mass of the electron; Based on the above formula, the signal of the rotating device 8 is connected to the controller, and the controller can change the size of the magnetic field Bz by regulating the rotating device 8, so the particle rotation angle can be adjusted by adjusting the magnetic field to control the size.

[0041] The particle energy analysis device designed by the utility model can realize the electrons rotating at different angles in the angle space (θx, θy) by controlling the magnetic field. This can change the interface through the entrance slit 4. Equivalently, refer to Figure 6 It can be regarded as the entrance slit 4 rotating around the z axis. By continuously testing different angles The following data, usually The step length is 0.1° to 2°. Through data processing, the complete data of the angle space (θx, θy) can be restored. The dotted line 11 represents the rotation angle. The achievable measurement range, whose dotted diameter corresponds to the effective acceptance angle range of the lens system 2. The common range is ±15°, and the active lens can achieve ±90°. Figure 6a It can also be seen that the center data is denser and the edge data is sparser. This can be processed by mathematical interpolation. This embodiment, as shown in IOP Conf. Series Journal of Physics Conf. Series 849 (2017) 012019, uses the equivalent measurement effect of sample rotation. Compared with sample rotation, this patent avoids sample rotation and can greatly improve efficiency.

[0042] Figure 6 b further shows that the (0,0) point of the angle space (θx, θy) of the sample to be tested is offset by (θx0, θy0) relative to the center of the slit. At this time, the rotation angle is controlled by rotating the device 8 The measurement range 11 covered is a circle centered at (θx0, θy0). For a lens system 2 with a ±15° acceptance angle, the measurement area can be selected by offsetting the sample angle (θx0, θy0). For a lens system 2 with a ±90° acceptance angle, full-angle reception has been achieved, and no such deflection is required.

[0043] In this embodiment, the rotating device 8 comprises a coil 8 a arranged outside a certain stage of the lens. When the coil 8 a is energized, a magnetic field arranged along the optical axis 10 is generated inside the lens.

[0044] In this embodiment, the coil 8a can be composed of 1, 2, 3 or more coils arranged in parallel. Figure 5 As shown; multiple coils can provide a more uniform magnetic field, as well as a more precise and diverse magnetic field distribution Bz control method.

[0045] Example 2

[0046] On the basis of the above-mentioned embodiment 1, the lens structure is optimized, that is, the lens closest to the sample 1 adopts an active lens 2a, and the lens close to the detection device 3 adopts a passive lens 2b; the active lens 2a has a high voltage, which can suck the particles into the lens system and converge at one place; the passive lens is grounded or at a very low voltage, and the particles fly freely; a rotating device 8 is set in the convergence area, and the particles enter the entrance slit 4 after rotating under the action of the magnetic field.

[0047] More specifically, the active lens 2a can achieve a full spatial acceptance angle of ±90°, sucking all the exit angle particles of the sample 1 into the lens system; then passing through the center of the rotating device 8 as a real space image (x, y). After the image is rotated by the rotating device 8, it is transmitted to the entrance slit 4 by the passive lens 2b to form an angle space (θx, θy) or momentum space (kx, ky) image. The angle of rotation of the rotating device 8 The same rotation angle also occurs at slit 4 Therefore, the measurement of the angle space (θx, θy) or momentum space (kx, ky) image is achieved by rotation.

[0048] Here, the rotation of the particle beam by the rotating device 8 is not necessarily limited to real space or angle space, and the imaging at the slit 4 is not necessarily limited to such forms. For example, it is possible to rotate in angle space (θx, θy) and measure at the slit 4 with a spatial image (x, y); or to rotate in a real space image (x, y) and measure at the slit 4 with a spatial image (x, y), etc.

[0049] Example 3

[0050] Based on the technical solution described in the above embodiment 2, the lens structure at the installation location of the rotating device 8 can be optimized as a reference. Figure 4 As shown, in the electrostatic lens system 2, the size of the lens where the rotating device 8 is installed can be designed according to the degree of particle convergence, that is, the lens where the rotating device 8 is installed should be narrower than the active lens on the entrance side.

[0051] Example 4

[0052] The detection device 3 in the present application is not limited to the hemispherical energy analyzer and can be replaced by other detection devices that can achieve the same function.

[0053] The above embodiments are only used to illustrate the design ideas and features of the utility model, and their purpose is to enable those skilled in the art to understand the content of the utility model and implement it accordingly. The protection scope of the utility model is not limited to the above embodiments. Therefore, any equivalent changes or modifications made based on the principles and design ideas disclosed by the utility model are within the protection scope of the utility model.

Claims

1. A particle energy analysis device, characterized in that: include: A detection device (3) and a lens system (2); the lens system (2) has a straight optical axis; a rotating device (8) is arranged inside the lens system (2); the rotating device (8) generates an adjustable magnetic field, and particles change their rotation angle under the action of the magnetic field generated by the rotating device (8); the direction of the magnetic field is parallel to the optical axis on the optical axis; charged particles passing through the magnetic field rotate around the optical axis; The lens system (2) comprises a plurality of lenses, the plurality of lenses being arranged in sequence along the optical axis (10), and each lens stage being symmetrically distributed about the optical axis (10); A rotating device (8) is arranged on one or more lenses in the lens system (2).

2. A particle energy analysis device according to claim 1, characterized in that: The signal of the rotating device (8) is connected to the control unit, and the rotation angle of the particles is controlled by regulating the magnetic field generated by the rotating device (8).

3. The particle energy analysis device according to claim 1, characterized in that: The rotating device (8) comprises at least one magnetic coil (8a).

4. A particle energy analysis device according to claim 3, characterized in that: The lens closest to the sample is an active lens, and a rotating device (8) is arranged on the lens behind the active lens.

5. The particle energy analysis device according to claim 1, characterized in that: The detection device (3) comprises a particle detector (7), and the particle detector (7) is used to detect the position of the charged particle, and the position includes at least one parameter.

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