CN212648184U - Multi-electron beam focusing device - Google Patents

Abstract

The utility model discloses a many electron beams focusing device, this system includes hot or cold field emission cathode electron source and the grid that is used for producing the electron beam, the beam splitter of electron beam splitting, the accelerating lens that improves the electron beam energy, improve the phase difference lens that disappears of electron beam quality, to the high-resolution objective array of each electron beam spot, the electron beam deflector who finely tunes and the beam brake that control electron beam passes through are carried out to the electron beam position, so that to the accurate control of electron beam, consequently can hold the electron beam that the quantity is more on the round crystal of the same area and realize simultaneous exposure, precision and speed in the integrated circuit processing is used have been improved.

Description

Multi-electron beam focusing device

Technical Field

The utility model relates to a high meticulous semiconductor processing field especially relates to a many electron beam focusing device.

Background

Integrated circuit performance, such as operating speed and memory density, has in the past followed moore's law. The speed and strength of the process have been increasing during the last decades, and the development of chip processing technology has been driven, so as to develop a processing technology with higher resolution. Until now, high-yield and high-definition patterning processing equipment is the core equipment of the semiconductor industry, and the current advanced chip processing needs 30 to 50 times of exposure process, and the cost of the whole exposure process accounts for about 1/3 of the integrated circuit processing cost. Lithography machines have evolved to the current semiconductor processing industry as the only option for exposure equipment to meet the needs of the industry.

In addition to euv optical exposure, electron beam exposure machines are one of two means by which modern nanofabrication processes can achieve single nanometer (<10nm) patterning. The electron beam exposure machine easily obtains a fine pattern of nanometer resolution because the wavelength of the electron beam is short and there is no limitation of diffraction effect, thereby realizing high resolution. Meanwhile, the exposure of the device is realized by directly controlling the electron beam by CAD design software without preparing a mask in advance, so that the research and development period of the device can be greatly shortened. More importantly, the price of the electron beam exposure machine is two orders of magnitude lower than that of the photoetching machine under the condition of achieving the same processing precision. However, most of the current electron beam exposure machines are single-beam scanning type, the yield is very low, the industrial mass production requirements cannot be met, the current electron beam exposure machines are excluded from production lines, and users of the single-beam scanning electron beam exposure machines are only limited to scientific research groups, industrial research and development and mask preparation of photoetching machines.

The yield of the electron beam exposure machine can be improved by improving the scanning speed, however, the scanning speed of the single-beam scanning electron beam exposure machine is between 50MHz and 100MHz at present, and the rise space is very limited. Increasing the beam current is also a solution, but at the cost of an increased beam spot of the electron beam, the resolution of the system is rather reduced, which is not worth paying. The most effective way is by increasing the number of electron beams. The large number of electron beams processed in an array is far more efficient than a single point source exposure. The development of multi-beam electron beam exposure machines has been started around 1980 by the japan institute of physical and chemical research, and the research of the multi-electron beam parallel exposure technology has been conducted in a small number of units in the world. However, with the increasingly clear and mass-producible features of Deep Ultraviolet (DUV) and Extreme Ultraviolet (EUV) technology prospects, mainstream technology does not see the prospects of multibeam electron beam exposure machines, and thus has been developing slowly over the years.

Currently, imsnanof exposure is the only commercial multibeam exposure machine, but it is limited to the fabrication of 30 nm line width with 26 ten thousand beamlets for the fabrication of 7 nm node integrated circuit optical exposure mask (the beam spot of each beamlet of the machine can only be focused to 20 nm). Mapper corporation, the netherlands, currently develops its third generation system FLX, and is dedicated to the development of 650000 daughter electron beam systems, in an attempt to achieve a yield of 40 wafers per hour at a 28 nanometer node. Unfortunately, Mapper declared a failure in 2018 due to capital concerns, and FLX prospects were unknown.

Even so, the multi-beam electron beam exposure machine still has a great market prospect. At present, the one-time investment cost of a machine table of a deep ultraviolet lithography machine and an extreme ultraviolet lithography machine is high, for example, the price of an immersion type DUV lithography machine which can meet the requirement of a 14 nanometer node is more than 7500 ten thousand dollars. The photomask set required for the lithography machine to pattern is around ten million dollars. Such high investment has greatly limited the technological development of application-specific integrated circuits, such as internet of things chips and artificial intelligence chips. The multi-beam electron beam exposure machine has low cost, and if the yield of 20-30 chips with 8 inches exposed per hour can be realized, the performance of the Internet of things chip and the artificial intelligent chip can be rapidly improved and produced, so that a new semiconductor industry ecology is formed. Generally, the implementation of multiple electron beams is as follows:

one is to generate an electron beam using a single electron emission source, and the electron beam is focused by a single electron optical system after being divided into a plurality of beams by an aperture array. Its advantages are that the electron beams are generated from same emitter, and the current density and brightness are not uniform. Its significant disadvantage is that the beam focusing caused by the non-uniform spatial field distribution of the focusing elements is very difficult, and the beam spot of each electron beam is also difficult to be uniform. The technical route is therefore limited to only a few tens of electron beams, such as the 61-beam and 91-beam scanning electron microscopes published by zeiss, and electron beam arrays larger than 100 have not been reported.

Another approach is to form multiple electron beams in an array of multiple single electron beam systems. This has the advantage that each electron beam is a separate module, independent of each other and individually controllable. Due to the adoption of a modular design mode, a large number of modules can be randomly spliced after a single module is completed. Meanwhile, each module only contains a single electron beam, so the electron optics design of the module is simpler and more effective, the quality of the electron beams is higher, and the size of the beam spot which can be achieved is less than 5 nm. With this technical route, the research results of the existing single-electron-beam exposure system can be used for reference, and thus, have been adopted by research teams in the united states and korea. With this solution, however, the number of beams is entirely dependent on the size of the individual module, which is currently found in the literature to be 2 cm by 2 cm, thus accommodating only 16 beams on a 4 "wafer. Increasing the electron beam can only reduce the size of a single module, however it is foreseeable that there is limited room for improvement using this technical route.

The third is to generate multiple electron beams by electron emission arrays instead of beam splitters, such as thermal field emission cathode arrays and photo-cathode arrays. Compared with a single electron source, the emission current of the cathode array is distributed on a larger plane, the coulomb effect is greatly reduced, the current density of a single electron beam is larger, and higher electron beam energy can be used. In experiments, good results were also obtained with the cathode array. However, in a production environment, the electron beam exposure machine needs to continuously and stably operate for a long time, and the requirements on the emission capability and the consistency of the cathode are high. Hot cathodes such as film-coated barium tungsten cathodes have been used and tested for a long time, have advantages in uniform emission and service life, and also meet the requirements of brightness and emission current. The photocathode array is not applied in the production line, and further verification is needed.

And the fourth is that the single electron emission source is focused by the micro electron optical array after being divided into a plurality of beams by the beam splitter. Mapper also adopts the technical route. Mapper uses a total of 650000 beams in order to implement the "pattern beam" concept and increase the total beam current. Wherein the electron optical system array comprises 13000 units, each unit being adapted to focus 7 × 7 to 49 electron beams. The difficulty of electron transmission focusing is overcome when the mass electron beam quantity is realized, and especially the realization difficulty is very high when the small beam spots of 49 sub-electron beams are obtained within the limited focusing capacity of the microcell.

SUMMERY OF THE UTILITY MODEL

In order to overcome the defects of the prior art, the utility model provides a multi-electron beam focusing device which can solve the difficulties of the generation, transmission and focusing of multi-electron beams.

In order to solve the technical problem, the utility model provides a following technical scheme:

a multi-electron beam focusing device comprises an electron beam emission source, a beam splitter, an accelerating lens, a phase difference eliminating lens, an objective lens array, an electron beam deflector and a beam gate which are sequentially arranged along the electron beam emission direction;

the electron beam generated by the electron beam emission source is sequentially split by the beam splitter, the energy of the electron beam is improved by the accelerating lens, the phase difference is eliminated by the phase difference eliminating lens, the quality of the electron beam is improved, the beam spot of each electron beam is focused by the objective lens array, the resolution ratio is improved, and after the position of the electron beam is finely adjusted by the electron beam deflector, the conduction or the disconnection of the electron beam is controlled by the beam gate.

As a preferable embodiment of the present invention, the electron beam emission source includes a cathode electron source for generating an electron beam and a grid electrode for emitting the electron beam, and the cathode electron source is disposed in the grid electrode.

As a preferred technical solution of the present invention, the cathode electron source includes, but is not limited to, a tungsten metal needle tip with a zirconium oxide plated surface.

As an optimal technical scheme of the utility model, be provided with the beam splitting micropore that a plurality of arrays set up on the beam splitter, the surface coating of beam splitter has the graphite layer.

As a preferable embodiment of the present invention, the accelerating lens is applied with a high voltage electrostatic field.

As an optimal technical solution of the present invention, the number of the electron beam deflectors corresponds to the number of the divided electron beams, the multi-electron beam focusing apparatus further includes a first processor for controlling the operating status of the electron beam deflectors, and the first processor is electrically connected to the electron beam deflectors through a data bus.

As a preferred technical scheme of the utility model, the electron beam deflector includes first biasing electrode, second biasing electrode, third biasing electrode, fourth biasing electrode and digital analog conversion module, and four biasing electrodes are arranged in four circuit layers respectively, and every biasing electrode all is connected with first treater electricity through digital analog conversion module, data bus.

As a preferred technical scheme of the utility model, four biasing electrodes center on and form annular structure.

As an optimized technical scheme of the utility model, the electron beam one-to-one after restrainting floodgate quantity and beam splitting, many electron beam focusing device is still including the second treater that is used for controlling the operating condition who restraints the floodgate, the second treater passes through the photoelectric transmission module and restraints the floodgate electricity and be connected.

As a preferred technical scheme of the utility model, the floodgate is restrainted including first bundle of floodgate electrode, second bundle of floodgate electrode and photoelectric transmission module, and two bundle of floodgate electrodes are arranged in two circuit layers respectively, and one of them ground connection, the other is bias voltage, and all bundles of floodgates all have the same bias voltage, it is connected with the second treater electricity through photoelectric transmission module to restraint the floodgate.

Compared with the prior art, the utility model discloses the beneficial effect that can reach is:

the utility model discloses many electron beam focusing device, by the electron beam that the electron beam emission source produced improves the energy of electron beam, lens acceleration in proper order through the beam splitter beam splitting, eliminates to differ and improves electron beam quality, objective array and focuses on the beam spot of each electron beam and improve resolution ratio to behind the position by electron beam deflector fine setting electron beam, by switching on or turn-off of beam brake control electron beam, improved the resolution ratio of electron beam. In addition, each electron beam is provided with a special electron optical system, a deflection system and a beam gate so as to be convenient for the precise control of the electron beams, so that more electron beams can be accommodated on the round crystal with the same area to realize the simultaneous exposure, and the precision and the speed in the integrated circuit processing application are improved.

Drawings

FIG. 1 is a schematic block diagram of a multi-beam electron beam generation, transmission and focusing system of the present invention;

FIG. 2 is a schematic view of an electron source and beam splitter according to the present invention;

fig. 3 is a top view of the electron beam biasing electrode of the present invention;

fig. 4 is a side view of the electron beam biasing electrode of the present invention;

fig. 5 is a schematic diagram of a control circuit of the electron beam deflector of the present invention;

fig. 6 is a top view of the electron beam shutter electrode of the present invention;

fig. 7 is a side view of the electron beam shutter electrode of the present invention;

fig. 8 is a schematic diagram of a control circuit of the electron beam shutter according to the present invention;

fig. 9 is a schematic structural diagram of an objective lens array of the multi-electron beam focusing apparatus of the present invention.

Wherein: 1. an electron beam emission source; 11. a cathode electron source; 12. a gate electrode; 2. a beam splitter 3, an acceleration lens; 4. a phase difference eliminating lens; 5. an objective lens array; 6. an electron beam deflector; 61. a first bias electrode; 62. a second bias electrode; 63. a third bias electrode; 64. a fourth bias electrode; 7. a beam gate; 71. a first beam gate electrode; 72. a second beam gate electrode

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are presented herein only to illustrate and explain the present invention, and not to limit the present invention.

Please refer to fig. 1-8, the utility model provides a multi-electron beam focusing device, the system includes an electron beam emission source 1 for generating electron beams, a beam splitter 2 for beam splitting of electron beams, an accelerating lens 3 for improving the energy of electron beams, a phase difference eliminating lens 4 for improving the quality of electron beams, a high-resolution objective array 5 for each electron beam spot, an electron beam deflector 6 for fine tuning the position of electron beams and a beam gate 7 for controlling the passing of electron beams, the beam gate 7 and the electron beam deflector 6 are both connected with a control circuit, whether a single electron beam deflects and the on-off is controlled, so as to control the electron beams accurately, therefore, more electron beams can be accommodated on the circular crystal with the same area to realize the simultaneous exposure, and the precision and the speed in the integrated circuit processing application are improved.

In precision electron beam optical systems, since the electromagnetic fields of adjacent cells in a micro electron optical array are not completely isolated, the effects of surrounding cells need to be considered at the time of design, and the entire spatial field of a cell needs to be accurately calculated if multiple electron beams need to be transmitted in a single cell. Meanwhile, the whole optical system has small size and relatively weak focusing capability, so that the design difficulty is much higher. As shown in fig. 9, the objective lens array 5 is a micro objective lens array, a small gap is formed between the two objective lenses, each electron beam is focused by the corresponding objective lens, and no electron beam passes through the gap between the objective lenses. The utility model discloses an every electron beam all focuses on by independent miniature electron optical unit, can simplify the design like this, obtains littleer electron beam spot. For example, when a 100 row and 100 column beam splitting array is employed, a single focusing unit can focus a beam current of 0.2 microamperes to a beam spot of several nanometers, as shown in FIG. 2.

In an alternative embodiment, electron beam emitter 1 comprises cathode electron source 11 and grid 12, which are emitted from the metal surface by the external electric force of the grid voltage. In this embodiment, the thermal field emission cathode electron source or the cold field emission cathode electron source includes, but is not limited to, a tungsten metal tip with a surface plated with zirconia, although other electron emission materials can be used.

The beam splitter 2 is provided with a plurality of beam splitting micropores arranged in an array, and the surface of the beam splitter 2 is coated with a graphite layer which is positioned at the emission side of the electron beam emission source 1 of the beam splitter 2. The accelerating lens 3 is applied with a high-voltage electrostatic field with the voltage of 15KV, so that the energy of the split electrons is enhanced.

The number of the electron beam deflectors 6 corresponds to the number of the split electron beams one by one, and the multi-electron beam focusing device further comprises a first processor for controlling the working state of the electron beam deflectors 6, wherein the first processor is electrically connected with the electron beam deflectors 6 through a data bus.

As shown in fig. 4, the electron beam deflector 6 includes a first bias electrode 61, a second bias electrode 62, a third bias electrode 63, a fourth bias electrode 64, and a digital-to-analog conversion module, the four bias electrodes surround to form a ring structure, the four bias electrodes are respectively disposed in four circuit layers, and each bias electrode is electrically connected to the first processor through the digital-to-analog conversion module and a data bus.

Fine tuning of the beam spot position of the electron beam is achieved by means of the electron beam deflector. Because of the large number of electron beams, the ideal beam optics cannot minimize the beam spot of all electron beams, and therefore each beam end system needs to be equipped with a separate beam deflector. The electron beam deflector uses electrostatic deflection, and the position of the electron beam is adjusted by changing the deflection voltage. And a plurality of deflection electrodes are configured to achieve a good deflection effect and are respectively stacked in different circuit layers. Each deflection electrode needs to be configured independently, the voltage value needing to be configured is transmitted to a front-end processing circuit through a data bus, the voltage value is converted into a bias voltage through digital-to-analog conversion, and the maximum bias voltage is determined by the needed deflection amount.

The number of the beam brakes 7 corresponds to the number of the split electron beams one by one, the multi-electron beam focusing device further comprises a second processor for controlling the working state of the beam brakes 7, and the second processor is electrically connected with the beam brakes 7 through a photoelectric transmission module.

In this embodiment, the beam gate 7 includes a first beam gate electrode 71, a second beam gate electrode 72, and a photoelectric transmission module, the two beam gate electrodes are respectively disposed in two circuit layers, one of the two beam gate electrodes is grounded, the other one is a bias voltage, all the beam gates 7 have the same bias voltage, and the beam gate 7 is electrically connected to the second processor through the photoelectric transmission module.

In order to accelerate the yield of the electron beam exposure machine, the utility model discloses a many electron beam focusing device, every electron beam all is equipped with independent beam floodgate to block or pass through the electron beam, form the figure of waiting to process the wafer. The beam brake functions relatively singly, and in the blocking state, the electron beam position is only deflected to the outside of the electron beam aperture, so that only a single electrode is needed, and all the electrodes can use the same bias voltage, so that the circuit design is much simpler than that of the deflector. The biggest difficulty of the beam gate, however, is the requirement of high-speed dynamic response, the total data bandwidth of which is the product of the exposure frequency of the electron exposure machine and the number of electron beams. In order to increase the scanning speed, the beam shutter needs to operate at high speed to operate each sub-beam. The utility model discloses a many optic fibres carry out signal distribution, and the cell array quantity that every optic fibre is responsible for is decided by data processor's bandwidth, generally is tens to hundreds of arrays, like the cell array of 10 lines 10 rows. The control data of the unit array is transmitted in a serial mode, and when reaching the beam gate, the control data are converted from serial to parallel, and meanwhile, the corresponding number of beam gate array units are driven to be switched on and off.

Based on foretell many electron beam focusing devices, the utility model discloses still provide an electron beam control method, it includes following step:

s10, emitting the electron beam generated by the electron beam emitting source;

s20, the electron beam is split by the beam splitter and emitted to the accelerating lens;

s30, increasing the energy of the electron beam by the accelerating lens to accelerate the electron beam to the phase difference eliminating lens;

s40, eliminating phase difference by the phase difference eliminating lens to improve the quality of the electron beam;

s50, focusing the beam spots of the electron beams by using the objective lens array, reducing the radius of the beam spots of the electron beams and improving the resolution of exposure by using the electron beams;

and S60, after the position of the electron beam is finely adjusted by the electron beam deflector, controlling whether the electron beam is emitted outwards by the beam gate.

In the electron beam control method of the present invention, the steps of generating, transmitting and focusing the electron beam are as follows:

1. the electron beam is generated by a single tungsten metal needle point with the surface plated with zirconium oxide, and after the tungsten metal needle point is heated, the energy of free electrons is greater than work function and then the free electrons are emitted from the metal surface under the external electric field force of grid voltage. The grid voltage is between 50 and 100V, and if the grid voltage is too large, the electron beam is easy to generate unnecessary secondary electrons when being impacted on the beam splitter. Moreover, the voltage of 50-100V can ensure that the service life of the cathode exceeds 1000 hours, the uniformity of current density is good, the current intensity is about 5mA, and the continuous and stable working capability for a long time is realized. After electron emission, the electron beam is divided into 10000 parts of electron beams by a miniature 100 x 100 beam splitter, the diameter of a circular hole in the beam splitter is 15 micrometers, the distance between the centers of adjacent circular holes is 22 micrometers, as shown in fig. 2, each part of electron beams carries 0.2 microampere of current, so that a nanoscale light spot can be obtained during subsequent focusing.

2. Then each sub electron beam is accelerated to higher energy under the electric field force of the acceleration voltage, the stronger the energy carried by the electron is, the stronger the exposure capability is, and the higher the yield of the exposure machine is. However, too high beam energy also requires that the focusing and deflection circuits need to operate at higher voltages, which makes the design more difficult, and therefore the accelerating voltage is 15 kv.

3. After each sub-electron beam passes through the corresponding phase difference eliminating electrostatic lens and the corresponding focusing objective lens array, the energy dispersion of the electron beam is reduced, the electron beam is focused, and the beam spot is reduced. The space electromagnetic field of the micro electron optical array subelement is obtained by calculation through a finite element method, the element field is expanded to a neighboring element through a periodic boundary mode, and the whole space field is used for accurately calculating the movement of the electron beam in the micro electron optical array. The structural parameters and voltages of the electron optical system are simulated and optimized by a large amount to finally obtain the minimum beam spot. The results show that a 15kv electron beam of 0.2 microamperes can be focused to a spot of 10 nm.

4. Due to the spatial distribution of the electrons themselves, it is not possible for the electron optical system to have all the electrons in optimal focus, and therefore it is necessary to fine-tune their configuration. Thus, after the electron optical array, the position and the beam spot size of each electron beam can be finely adjusted by the independent deflector. The electron deflector is composed of 4 electrodes, and different voltage values can be loaded in 4 circuit layers respectively, and the structure of the electron deflector is shown in fig. 3 and 4. The set voltage value is sent by a control program, reaches a corresponding electronic deflector circuit through a bus system, is subjected to digital-to-analog conversion, and then is obtained by an amplifier. The voltages of the 4 electrodes have different polarities plus various voltage combinations to shift the electrons to any position in the central hole. The voltage values after rectification are stored as rectification parameters, as shown in fig. 5.

5. In the application of the electron beam exposure machine, various patterns need to be exposed, which is realized by controlling the on and off of the electron beam, namely a beam gate, as shown in fig. 6 and 7. After passing through the electron beam deflector, each sub electron beam is in a correct state, the beam gate is not biased, the electron beam normally passes through to carry out exposure, and if the beam gate is biased, the electron beam is deflected and cannot pass through the central hole, and exposure cannot be carried out. Since the beam gate has only two states, on and off, there is no need for a fine selection of the deflection voltage, so all beam gates share the same operating voltage. In this case, a signal distribution system using a plurality of optical fibers is used, and on/off signals are transmitted to respective control circuits by a photoelectric conversion circuit. Calculated by 10MHz exposure frequency and 10000 electron beams, the data bandwidth is 100 Gb. In the case of using 100 optical fibers, each data bandwidth is 1 Gb. Each fiber serially transmits a single 10 × 10 array of data, and after serial-to-parallel conversion, simultaneously drives 10 × 10 array elements on and off, as shown in fig. 8.

The utility model discloses a to the electron beam splitting, then make the electron accelerate through exerting voltage on accelerating lens, eliminate again by eliminating the phase difference lens and improve the electron beam quality, later focus the beam spot by miniature objective array again and carry out emergent after improving resolution ratio, from the exposure that is used for integrated circuit, improve the precision of integrated electronic product to reduce optical system's cost.

The embodiments of the present invention are not limited to the above embodiments, and according to the contents of the above embodiments of the present invention, the above preferred embodiments can also make modifications, replacements or combinations of other forms by using conventional technical knowledge and conventional means in the field without departing from the basic technical idea of the present invention, and the obtained other embodiments all fall within the scope of the present invention.

Claims (9)

1. A multi-electron beam focusing apparatus, characterized in that: the device comprises an electron beam emission source (1), a beam splitter (2), an accelerating lens (3), a phase difference eliminating lens (4), an objective lens array (5), an electron beam deflector (6) and a beam gate (7) which are sequentially arranged along the electron beam emission direction;

the electron beam generated by the electron beam emission source (1) is sequentially split by the beam splitter (2), the energy of the electron beam is improved by the accelerating lens (3), the phase difference is eliminated by the phase difference eliminating lens (4) to improve the quality of the electron beam, the beam spot of each electron beam is focused by the objective lens array (5) to improve the resolution, and after the position of the electron beam is finely adjusted by the electron beam deflector (6), the conduction or the disconnection of the electron beam is controlled by the beam gate (7).

2. The multi electron beam focusing device according to claim 1, wherein the electron beam emission source (1) includes a cathode electron source (11) for generating an electron beam and a grid electrode (12) for emitting the electron beam, the cathode electron source (11) being disposed in the grid electrode (12).

3. The multi electron beam focusing device according to claim 2, wherein the cathode electron source (11) comprises, but is not limited to, a tungsten metal tip surface-coated with zirconia.

4. The multi-electron beam focusing device according to claim 1, wherein the beam splitter (2) is provided with a plurality of beam splitting micro-holes arranged in an array, and the surface of the beam splitter (2) is coated with a graphite layer.

5. The multi-electron beam focusing device according to claim 1 or 3, wherein the number of the electron beam deflectors (6) corresponds to the number of the divided electron beams, and the multi-electron beam focusing device further comprises a first processor for controlling the operation state of the electron beam deflectors (6), and the first processor is electrically connected to the electron beam deflectors (6) through a data bus.

6. The multi electron beam focusing device according to claim 5, wherein the electron beam deflector (6) comprises a first bias electrode (61), a second bias electrode (62), a third bias electrode (63), a fourth bias electrode (64) and a digital-to-analog conversion module, the four bias electrodes are respectively disposed in four circuit layers, and each bias electrode is electrically connected to the first processor through the digital-to-analog conversion module and a data bus.

7. The multi-electron beam focusing device of claim 6, wherein four bias electrodes surround a ring structure.

8. The multi-electron beam focusing device according to claim 6, wherein the number of the beam shutters (7) corresponds to the number of the split electron beams, and the multi-electron beam focusing device further comprises a second processor for controlling the operating state of the beam shutters (7), and the second processor is electrically connected with the beam shutters (7) through the photoelectric transmission module.

9. The multi-electron beam focusing device according to claim 8, wherein the beam gate (7) comprises a first beam gate electrode (71), a second beam gate electrode (72) and a photo-electric transmission module, the two beam gate electrodes are respectively disposed in two circuit layers, one of which is grounded and the other is a bias voltage, all the beam gates (7) have the same bias voltage, and the beam gates (7) are electrically connected to the second processor through the photo-electric transmission module.

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