Electron guns, electron beam application devices, and electron beam emission methods

Abstract

The present invention provides an electron gun with only the components of an electron gun, namely, an electron gun that can be set to irradiate an electron beam with desired electron beam parameters at a desired location of an irradiated object. The electron gun includes: a light source; a photocathode that generates emitable electrons based on light received from the light source; an anode that can form an electric field with the photocathode and draw out the emitable electrons through the formed electric field to form an electron beam; and a control unit. The control unit sets the number of times the electron beam is emitted and sets the electron beam parameters for each emitted electron beam, or sets the emission time of the electron beam and establishes a correlation between the electron beam parameters of the emitted electron beam and the emission time.

Description

[Technical Field]

[0001] The disclosure of this case relates to an electron gun, an electron beam application device, and a method for emitting an electron beam. [Previous Technology]

[0002] Electron beam application devices such as electron guns equipped with photocathodes, electron microscopes containing such electron guns, free electron laser (FEL) accelerators, and inspection devices are known (hereinafter, devices from which electron guns are detached from electron beam application devices are also referred to as "partner devices"). For example, Patent Document 1 discloses an electron microscope device that uses a photocathode that emits an electron beam by irradiating excitation light with a self-source light source.

[0003] As another example of an electron beam application device using a photocathode that emits an electron beam, a sample inspection device has been disclosed in Patent Document 2. The sample inspection device described in Patent Document 2 is known to adjust the amount of pulsed light in response to the condition that the sample is susceptible to heat damage, etc.

[0004] Furthermore, it is known that in electron beam application devices such as electron microscopes or electron beam inspection devices, regardless of the configuration of the partner device, the intensity of the electron beam is adjusted by components on the electron gun side. For example, Patent Document 3 discloses that the intensity of the electron beam emitted from the photocathode is adjusted by an electron beam shielding member, a measuring unit, and a control unit. The electron beam shielding member shields a portion of the electron beam, and the measuring unit uses the measuring electron beam shielded by the electron beam shielding member to measure the intensity change of the electron beam emitted from the photocathode as the photocathode deteriorates. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2002-313273. [Patent Document 2] Japanese Patent No. 6604649. [Patent Document 3] Japanese Patent No. 6578529. [Summary of the Invention]

[0006] 〔The problem that the invention aims to solve〕

[0007] Electron beam application devices are required to irradiate an object to be irradiated (hereinafter referred to as "irradiation object") with an electron beam of desired intensity and parameters (hereinafter referred to as "electron beam parameters"). Furthermore, regarding the types of electron guns, in addition to electron guns using photocathodes, electron guns using thermionic cathodes or field emitters are known. Therefore, it is conceivable that there are instances where a new electron gun using a photocathode is to be mounted on a partner device that already uses an electron gun using a thermionic cathode or field emitter.

[0008] Therefore, it is ideal that the constituent components, including an electron gun with a photocathode, can be configured to irradiate an object with an electron beam having the desired electron beam parameters. Furthermore, in order to further enhance the functionality of the electron beam application device, it is ideal that, in addition to irradiating each object with an electron beam having the desired electron beam parameters, it can also irradiate a desired position of the same object with an electron beam having the desired electron beam parameters.

[0009] However, the invention described in Patent Document 2 is merely a matter of setting the amount of light per unit time of the pulsed light to a constant, or gradually increasing or decreasing the amount of light per unit time of the pulsed light, depending on the type of sample. Furthermore, Patent Document 2 is an invention as an electron beam application device.

[0010] The invention described in Patent Document 3 relates to a feedback control method that uses a measuring electron beam shielded by a shielding member to adjust the intensity of the electron beam as it deteriorates with the photocathode. Therefore, the invention described in Patent Document 3 also has the problem of being unable to irradiate the desired position of the irradiated object with an electron beam having the desired electron beam parameters.

[0011] At present, there is no known electron gun or irradiation method that can be configured to irradiate an electron beam with desired electron beam parameters at a desired location of the irradiated object using only the constituent components of the electron gun.

[0012] This invention was created by the inventor in order to solve the above problems. After dedicated research, the inventor created a new invention that solves the above problems by having an electron gun with (1) setting the number of electron beams emitted and setting the electron beam parameters according to each emitted electron beam, or (2) setting the emission time of the electron beam and setting the electron beam parameters and emission time in relation to the emission time.

[0013] The disclosure of this case is to provide an electron gun that can be configured to irradiate an electron beam with desired electron beam parameters at a desired location on an irradiated object, using only the components of an electron gun; an electron beam application device equipped with the electron gun; and a method for emitting the electron beam. [Technical Means for Solving the Problem]

[0014] This case relates to the electron gun, electron beam application device, and electron beam emission method as shown below.

[0015] (1) An electron gun, comprising: a light source; a photocathode that generates emitable electrons based on light received from the light source; an anode that forms an electric field with the photocathode and draws out the emitable electrons through the formed electric field to form an electron beam; and a control unit; wherein the control unit sets the number of times the electron beam is emitted and sets electron beam parameters for each emitted electron beam, or sets the emission time of the electron beam and sets the electron beam parameters of the emitted electron beam in relation to the emission time. (2) In the electron gun described in (1) above, wherein the control unit sets the number of times the electron beam is emitted and sets electron beam parameters for each emitted electron beam, the electron beam parameters include at least one selected from the electron beam intensity, the electron beam acceleration energy, the electron beam size, the electron beam shape, the electron beam emission time, and the electron beam emissivity. (3) The electron gun described in (2) above, wherein the number of firings is two or more, and the control unit controls that at least one electron beam parameter is different from one of the other electron beam parameters when firing an electron beam of a set number of times. (4) The electron gun described in (1) above, wherein the control unit sets the firing time of the electron beam and sets the electron beam parameters of the fired electron beam in relation to the firing time, and the electron beam parameters include at least one selected from the electron beam intensity, the magnitude of the electron beam acceleration energy, the size of the electron beam, the shape of the electron beam, and the electron beam emission rate. (5) The electron gun described in (4) above, wherein the control unit controls that when firing an electron beam at the set firing time, it includes the time for firing an electron beam with different electron beam parameters. (6) The electron gun described in any one of (1) to (5) above irradiates excitation light from a light source at two or more different locations of the aforementioned photocathode, so as to draw out two or more electron beams from the aforementioned photocathode. (7) An electron beam application device includes the electron gun described in any one of (1) to (6) above. The electron beam application device is a free electron laser accelerator; an electron microscope; an electron beam holography device; an electron beam patterning device; an electron beam diffraction device; an electron beam inspection device; an electron beam metal layering device; an electron beam lithography device; an electron beam processing device; an electron beam hardening device; an electron beam sterilization device; an electron beam sterilization device; a plasma generation device; an atomic element generation device; a rotating polarized electron beam generation device; a cathode luminescence device; or a reverse photon radiograph device.(8) An electron beam emission method, wherein the electron beam is emitted from an electron gun, the electron gun comprising: a light source; a photocathode that generates emissible electrons based on light received from the aforementioned light source; an anode that forms an electric field with the aforementioned photocathode and draws out the emissible electrons through the formed electric field to form an electron beam; and a control unit; wherein the aforementioned control unit sets the number of times the aforementioned electron beam is emitted and sets electron beam parameters according to each emitted electron beam, or sets the emission time of the aforementioned electron beam and establishes a correlation between the electron beam parameters of the emitted electron beam and the aforementioned emission time for setting, the emission method comprising an electron beam emission step, wherein the electron beam emission step irradiates the aforementioned photocathode with excitation light from the aforementioned light source and draws out the emissible electrons generated by the aforementioned photocathode based on light received from the excitation light through an electric field formed between the aforementioned photocathode and the aforementioned anode to form an electron beam; The aforementioned control unit controls the emitted electron beam to meet the set electron beam parameters during the electron beam emission step. (9) In the emission method described in (8) above, the aforementioned control unit sets the number of electron beam emission times and sets electron beam parameters for each emitted electron beam. The aforementioned electron beam parameters include at least one selected from electron beam intensity, electron beam acceleration energy, electron beam size, electron beam shape, electron beam emission time, and electron beam emission rate. (10) In the emission method described in (9) above, the aforementioned number of emission times is two or more, and the aforementioned control unit controls that when emitting electron beams of the set number of times, at least one electron beam parameter is different from one selected from other electron beam parameters. (11) The emission method described in (8) above, wherein the aforementioned control unit sets the emission time of the aforementioned electron beam and establishes a relationship between the electron beam parameters of the emitted electron beam and the aforementioned emission time, wherein the aforementioned electron beam parameters include at least one selected from electron beam intensity, electron beam acceleration energy, electron beam size, electron beam shape, and electron beam emissivity. (12) The emission method described in (11) above, wherein the aforementioned control unit controls the emission of electron beams at the set emission time to include the time for emitting electron beams with different aforementioned electron beam parameters. [Effects of the Invention]

[0016] The electron gun disclosed in this case can be set to irradiate an electron beam with desired electron beam parameters at a desired location of the irradiated object.

Implementation Method

[0018] The following is a detailed description of the electron gun, electron beam application device, and electron beam emission method, with reference to the drawings. Furthermore, in this specification, components with the same or similar functions are given the same or similar symbols. Secondly, for components marked with the same or similar symbols, repeated descriptions may be omitted.

[0019] Furthermore, the positions, sizes, and ranges of the structures shown in the drawings are for ease of understanding and may not represent their actual positions, sizes, or ranges. Therefore, the disclosure in this case is not necessarily limited to the positions, sizes, and ranges shown in the drawings.

[0020] (First Embodiment of the Electron Gun) The electron gun 1A of the first embodiment will now be described with reference to Figures 1 to 3. Figure 1 is a schematic diagram showing the electron gun 1A of the first embodiment and the partner device E on which the electron gun 1A is mounted. Figure 2 is a schematic diagram showing the control unit 5 of the electron gun 1A. Figure 3 is a schematic diagram showing the control unit 5 controlling the set electron beam parameters.

[0021] The electron gun 1A in the first embodiment includes at least: a light source 2; a photocathode 3; an anode 4; and a control unit 5. The electron gun 1A may also optionally include a power supply 6 for generating an electric field between the photocathode 3 and the anode 4. Furthermore, in the example shown in FIG1, the electron beam application device is a SEM (Scanning Electron Microscope), and the partner device E includes an electron beam deflector 10. The electron beam deflector 10 is used to scan the electron beam B emitted by the electron gun 1A onto the sample S. Additionally, the example shown in FIG1 is an example of the partner device E. Although the illustration is omitted, the partner device E may have known constituent components depending on the type of electron beam application device.

[0022] There are no particular restrictions on the light source 2 as long as it can emit an electron beam B by irradiating the photocathode 3 with excitation light L. Examples of light sources 2 include high-output (watt-class), high-frequency (hundreds of MHz), ultrashort pulse laser light sources, relatively inexpensive laser diodes, and LEDs (light-emitting diodes). The irradiated excitation light L can be either pulsed light or continuous light, as long as it is appropriately adjusted according to the purpose. In the example shown in Figure 1, the light source 2 is disposed outside the vacuum chamber CB, and the excitation light L is irradiated on the first surface of the photocathode 3 (the surface on the anode 4 side). Alternatively, the light source 2 can also be disposed inside the vacuum chamber CB. Furthermore, the excitation light L can also irradiate the second surface of the photocathode 3 (the surface opposite to the anode 4).

[0023] The photocathode 3 generates electrons that can be emitted by receiving excitation light L from the light source 2. The principle by which the photocathode 3 generates electrons that can be emitted by receiving excitation light L is well known (for example, see Japanese Patent No. 5808021).

[0024] The photocathode 3 is formed from a substrate such as quartz glass or sapphire glass, and a photocathode film (not shown) attached to the first surface of the substrate (the surface on the anode 4 side). The photocathode material used to form the photocathode film is not particularly limited as long as it can generate emittable electrons by irradiation with excitation light. Examples include materials requiring EA surface treatment (electron affinity reduction treatment) and materials not requiring EA surface treatment. Examples of materials requiring EA surface treatment include, for example, III-V group semiconductor materials and II-VI group semiconductor materials. Specifically, examples include AlN, Ce2Te, GaN, compounds of one or more alkali metals and Sb, AlAs, GaP, GaAs, GaSb, InAs, and mixed crystals thereof. Other examples include metals, specifically Mg, Cu, Nb, LaB6, SeB6, Ag, etc. By performing EA surface treatment on the aforementioned photocathode material, a photocathode 3 can be prepared. This photocathode 3 not only becomes selectively excitation light in the near-ultraviolet-infrared wavelength region corresponding to the gap energy of the semiconductor, but also makes possible the performance of the electron beam source (quantum yield, durability, monochromaticity, time responsiveness, and spin polarization) corresponding to the application of the electron beam through the selection of semiconductor materials or structures.

[0025] Furthermore, examples of materials that do not require EA surface treatment include single metals such as Cu, Mg, Sm, Tb, and Y, as well as alloys, metal compounds, or materials such as diamond, WBaO, and Cs₂Te. Photocathodes that do not require EA surface treatment can be prepared using known methods (e.g., refer to Japanese Patent No. 3537779). The contents described in Japanese Patent No. 3537779 are incorporated herein by reference in their entirety.

[0026] In addition, although the terms "photocathode" and "cathode" in this specification are sometimes referred to as "photocathode" when referring to the emission of an electron beam, and as "cathode" when referring to the opposite pole to "anode", the symbol 3 is used regardless of whether it is "photocathode" or "cathode".

[0027] There are no particular restrictions on the anode 4 as long as it can form an electric field with the cathode 3. The anode 4 commonly used in the field of electron guns can be used. By forming an electric field between the cathode 3 and the anode 4, the electrons generated by the photocathode 3 can be extracted by the irradiation of the excitation light L to form an electron beam B.

[0028] Although Figure 1 shows an example of connecting the power supply 6 to the photocathode 3 to form an electric field between the cathode 3 and the anode 4, there are no particular restrictions on the configuration of the power supply 6 as long as a potential difference is generated between the cathode 3 and the anode 4.

[0029] Next, the control unit 5 of the electron gun 1A in the first embodiment will be described with reference to Figures 2 and 3. Figure 2 shows an example of the photocathode 3 receiving pulsed excitation light L, the control unit 5 setting the number of times the electron beam B is emitted, and setting the electron beam parameters (hereinafter referred to as "parameters") according to each emitted electron beam B.

[0030] The partner device E typically includes an electron beam deflection device 10 that deflects the electron beam B emitted by the electron gun 1A. For example, in the SEM example shown in FIG3, the electron beam B emitted by the electron gun 1A is scanned on the sample S (hereinafter referred to as the "irradiated object") by the electron beam deflection device 10.

[0031] However, the deflection of the electron beam B by the electron beam deflection device 10 usually scans the irradiation area R of the irradiated object in a linear manner. Therefore, the inventors have invented the following: (1) The number of times the electron beam B is emitted when irradiating the irradiation area R can be calculated based on the size of the irradiation area R, the size of the spot of the electron beam B in the irradiation area R, and the control speed of the electron beam deflection device 10 of the partner device E; (2) If the number of emission times can be set, the electron beam B with the desired parameters can be irradiated at the desired position of the irradiation area R by setting the parameters according to the parameters of each emitted electron beam B, by setting the electron gun 1A side. The disclosure in this case is based on this innovative insight.

[0032] The control of the control unit 5 will be described in further detail with reference to FIG2. In the example shown in FIG2, the electron beam deflection device 10 performs the following control: (a) The pulsed electron beam B emitted by the electron gun 1A is deflected from the left end (D1-1) of the initial line (L1) toward the right end and simultaneously irradiated. (b) After the electron beam B is irradiated at the point (D1-n) at the right end of L1, the irradiation position of the electron beam B is deflected toward the left end of the second line (L2), and the electron beam B is deflected from the left end to the right end and simultaneously irradiated in the same manner as in (a) above. (c) (b) above is repeated until the electron beam B is irradiated at the last point (Dm-n) of the irradiation area R.

[0033] Through the procedures described in (a) to (c) above, it can be understood that the electron beams B emitted sequentially from the electron gun 1A are planarly spread on the irradiation area R, and it can be understood that which part of the irradiation area R will be irradiated by which sequence of electron beams B emitted in that order. Therefore, for example, when the parameter of the electron beam B irradiating the irradiation area D1-1 is set to X, the electron beam B irradiating parameter X is up to D3-18, and for D3-19 to D3-25, the electron beam B to be irradiated with parameter Y can be set by the constituent members on the electron gun 1A side. Furthermore, the electron gun 1A can emit pulsed electron beams, so as shown in FIG2, the electron beam B with parameter Z can be irradiated for D8-4 to D8-8, then the electron beam B with parameter X is irradiated twice, and then the electron beam B with parameter Y is temporarily irradiated from position D8-11, and so on, so that detailed settings can be made on the electron gun 1A side.

[0034] Furthermore, in this specification, when it is described as "setting electron beam parameters according to each emitted electron beam", the control unit 5 not only sets the X, Y, Z, and other parameters for each emitted electron beam B, but also uniformly sets the parameters for a predetermined number of emitted electron beams B. If each electron beam B is emitted with X, Y, Z, and other parameters, the setting method of the control unit 5 is not particularly limited.

[0035] Furthermore, in the example shown in Figure 2, the control unit 5 controls that at least one parameter is different from one selected from other parameters when firing electron beams B a set number of times (D1-1 to Dm-n). In other words, it controls that the parameters of all electron beams B fired from D1-1 to Dm-n should not be the same. Alternatively, if the control unit 5 can be used to "set electron beam parameters according to each emitted electron beam", then it can also be set so that the parameters of all electron beams B fired from D1-1 to Dm-n become the same.

[0036] There are no particular restrictions on parameters that specify the quality of the electron beam. Examples of parameters are not limited, but can include the intensity of the electron beam, the magnitude of its acceleration energy, the size of the electron beam, the shape of the electron beam, the emission time of the electron beam, and the emissivity of the electron beam. When it is not necessary to make all the parameters of the electron beam B irradiating the irradiation area R the same, it is sufficient to make any one of the parameters listed above different. For example, this can be achieved by changing the intensity of one sequence of electron beams to that of another sequence, or by changing the acceleration energy of one sequence of electron beams to that of another sequence, by varying the intensity of the same type of parameter. Alternatively, different types of parameters can be set by simply changing the size or shape of the electron beam B in a certain sequence.

[0037] Of course, multiple parameters can be combined. For example, when the intensity of an electron beam in a certain sequence is set to 1 and the acceleration energy of the electron beam is set to 1, the intensity of an electron beam in another sequence is set to 1.5 and the acceleration energy of the electron beam is set to 1.5. In addition, not emitting an electron beam B (e.g., not irradiating the excitation light L for the photocathode 3) can also be set as one of the parameters.

[0038] A control example based on the parameters set by the control unit 5 will now be described with reference to FIG3. Furthermore, the following description is only one example of control. Other controls are also possible within the scope of the technical concept disclosed in this invention. In addition, to avoid complicating the diagram, there are cases where the control unit 5 is omitted, either in terms of circuitry or the description of its constituent components.

[0039] First, the control will be explained in the case where the set parameter is the intensity of the electron beam B. In this specification, "electron beam intensity" refers to the amount of electrons (current value) contained in the irradiated electron beam B. The intensity of the electron beam B depends on the amount of light emitted by the excitation light L irradiating the photocathode 3. Therefore, when the intensity of the electron beam B is set as a parameter, the control unit 5 controls the amount of light emitted by the excitation light L irradiating the photocathode 3 to achieve the set intensity of the electron beam B. In the example shown in Figure 1, the control unit 5 controls the amount of light emitted by the light source 2. Alternatively, a light intensity adjustment device 51, such as a liquid crystal shutter, can be installed between the light source 2 and the photocathode 3 to keep the amount of light emitted by the light source 2 constant, and the amount of light reaching the photocathode 3 can be controlled by controlling the liquid crystal shutter.

[0040] The acceleration energy of electron beam B can be controlled by changing the electric field strength between cathode 3 and anode 4. The greater the voltage difference between cathode 3 and anode 4, the greater the acceleration energy. Therefore, when the acceleration energy of electron beam B is set as a parameter, the control unit 5 controls the voltage of power supply 6 to achieve the set acceleration energy of electron beam B.

[0041] The size of the electron beam B can be controlled by changing the size of the excitation light L irradiating the photocathode 3. The larger the size of the excitation light L, the larger the size of the electron beam B. Therefore, when the size of the electron beam B is set as a parameter, the control unit 5 controls the excitation light size adjustment device 52, such as a lens or a liquid crystal shutter, to achieve the set size of the electron beam B. Alternatively, an electromagnetic lens or an aperture adjustment device 53 can be arbitrarily provided on the optical axis of the emitted electron beam B, and the control unit 5 controls the electron beam size adjustment device 53. Alternatively, an intermediate electrode 54 can be arbitrarily formed between the cathode 3 and the anode 4. The focal position of the electron beam B reaching the partner device E can be adjusted by the control unit 5 (1) adjusting the potential difference between the cathode 3, intermediate electrode 54, and anode 4 through the control power supply 6, or (2) adjusting the relative position of the cathode 3, intermediate electrode 54, and anode 4 by moving the control intermediate electrode 54. In other words, the size of the electron beam B reaching the irradiation area R can be controlled. In addition, the structure of the intermediate electrode 54, the control method, and the principle of controlling the focal position are detailed in Japanese Patent No. 6466020. The matters described in Japanese Patent No. 6466020 are included in this case by reference.

[0042] The shape of the electron beam B can be controlled by providing an electron beam shape adjustment device 55, such as an electromagnetic lens or an aperture, on the optical axis of the emitted electron beam B. Therefore, when the shape of the electron beam B is set as a parameter, the control unit 5 controls the electron beam shape adjustment device 55 to achieve the set shape of the electron beam B.

[0043] The emission time of the electron beam B can be controlled by the emission time of the excitation light L emitted by the light source 2. Therefore, when the emission time of the electron beam B is set as a parameter, the control unit 5 can control the ON-OFF of the light source 2 to achieve the set emission time of the electron beam B. Alternatively, although not shown, a shutter can be provided between the light source 2 and the photocathode 3, and the control unit 5 can control the shutter to control the emission time of the electron beam B.

[0044] The emissivity of the electron beam B can be controlled by the wavelength of the excitation light L emitted by the light source 2. Therefore, when the emissivity of the electron beam B is set as a parameter, the control unit 5 controls the wavelength of the excitation light L to achieve the set emissivity of the electron beam B. Although not shown, a known variable wavelength filter can also be provided between the light source 2 and the photocathode 3, and the control unit 5 can control the variable wavelength filter.

[0045] In the first embodiment, the electron gun 1A emits a pulsed electron beam B from the partner device E. Therefore, the electron beam deflecting device 10 of the partner device E deflects the emitted pulsed electron beam B sequentially from D1-1 towards Dm-n, as shown in FIG2. Thus, the electron gun 1A in the first embodiment can achieve the effect of irradiating the desired position of the irradiated object with an electron beam B having desired parameters using only the constituent components of the electron gun 1A.

[0046] (Modification of Control Unit 5) The control unit 5 described above displays the number of times the electron beam B is emitted, and sets parameters according to each emitted electron beam B. In other words, it is assumed that the electron beam B emitted by the electron gun 1A from the partner device E is a pulsed electron beam B. Alternatively, the electron beam B emitted by the electron gun 1A from the partner device E can also be a continuous electron beam B. As shown in FIG2, the electron beam B injected into the partner device E is scanned linearly from D1-1 to Dm-n by the electron beam deflection device 10. Therefore, the emission time of the electron beam B required to scan the irradiation area R can be calculated based on the size of the irradiation area R, the size of the electron beam B in the irradiation area R, and the control speed of the electron beam deflection device 10 of the partner device E.

[0047] When the time in D1-1 of the irradiation area R shown in Figure 2 is defined as t1 and the time in Dm-n is defined as tmn, it can be understood that the continuous electron beam B emitted from the electron gun 1A in the time sequence (t1 to tmn) is planarly unfolded on the irradiation area R, and it can be understood that the electron beam B emitted at which time will irradiate which part of the irradiation area R.

[0048] In the modified example, the control unit 5 sets the emission time of the electron beam B to be emitted, and sets the parameters of the emitted electron beam B in relation to the emission time. In the case of the modified example control unit 5, the electron beam B injected into the partner device E is continuously deflected from position D1-1 as shown in FIG2 toward position Dm-n. Therefore, among the parameters that can be set by the control unit 5 in the first embodiment, except for the parameter related to the emission time of the electron beam, all parameters (electron beam intensity, electron beam acceleration energy, electron beam size, electron beam shape, and electron beam emissivity) can be set in a manner related to the emission time.

[0049] The control unit 5 in the modified example, except for the parameter regarding the emission time of the electron beam, can perform control according to the set parameters in the same way as the control unit 5 in the first embodiment. Therefore, the electron gun 1A with the control unit 5 of the modified example can also achieve the effect of being able to irradiate the desired position of the irradiated object with an electron beam having the desired parameters using only the constituent components of the electron gun 1A.

[0050] (Second Embodiment of Electron Gun) The electron gun 1B of the second embodiment will now be described with reference to Figures 1 to 4. Figure 4 is an enlarged view of the photocathode 3 of the electron gun 1B of the second embodiment.

[0051] The electron gun 1B of the second embodiment irradiates excitation light L from a light source at two or more different locations of the photocathode 3 to extract two or more electron beams B from the photocathode 3. This differs from the electron gun 1A of the first embodiment. All other aspects are the same as in the first embodiment. Therefore, the description in the second embodiment focuses on the differences from the first embodiment, and matters already described in the first embodiment are omitted. Therefore, even if not explicitly stated in the second embodiment, matters already described in the first embodiment can naturally be used in the second embodiment. Similarly, the third and fourth embodiments described later are also omitted, but matters already described in the previous embodiments can naturally be used.

[0052] In order to irradiate the excitation light L from the light source 2 to two or more different locations of the photocathode 3, although not shown, a plurality of light sources 2 can be provided. Alternatively, the excitation light L from a single light source 2 can be split into two or more beams using an excitation light splitting device such as a splitter or a spatial phase modulator to irradiate the photocathode 3.

[0053] The electron gun 1B of the second embodiment can irradiate the irradiated object with multiple electron beams B. Therefore, in addition to the effects that the electron gun 1A of the first embodiment can achieve, the following effects can also be achieved: (1) When multiple electron beams B are irradiated on the irradiated object in a non-repetitive manner, the throughput can be improved. (2) When multiple electron beams B are irradiated on the irradiated object in a repetitive manner, the detection sensitivity of the partner device E can be improved, and the processing efficiency can be improved. (3) When multiple electron beams B are irradiated on the irradiated object in a repetitive manner, after the pump beam (irradiation time and charge amount) that imparts the desired effect to the irradiated object is irradiated, the next beam (detection beam) can be irradiated on the irradiated object at intervals. (4) In addition, when multiple electron beams B are irradiated on the irradiated object in a repetitive manner, it can also be used for the purpose of charge compensation of the irradiated object.

[0054] (Third Embodiment of Electron Gun) The electron gun 1C of the third embodiment will now be described with reference to FIG5. FIG5 is a schematic diagram showing the electron gun 1C of the third embodiment and the partner device E equipped with the electron gun 1C.

[0055] The parameters of the electron gun 1C in the third embodiment can be set by the control unit 5 with reference to information from the partner device E. This is different from the electron gun 1A in the first embodiment and the electron gun 1B in the second embodiment. However, all other aspects are the same as those in the first and second embodiments.

[0056] The electron gun 1C in the third embodiment includes an information display device 6 for referencing information from the partner device E. For example, when the electron beam application device is an electron microscope, the partner device E has a detector 7 that detects the signal obtained by irradiating the sample S with an electron beam B. The signal detected by the detector 7 can be processed and displayed on the information display device 6. The electron gun 1C in the third embodiment can have its parameters set by the control unit 5 based on the information displayed on the information display device 6.

[0057] More specifically, in the case of an electron microscope, an image of the captured sample S can be displayed on the information display device 6. Furthermore, in order to enhance the magnification or contrast of the displayed image, the location where the intensity of the electron beam B is to be changed is indicated by a pointer or similar device. The control unit 5 can set the number of times the electron beam B is emitted according to the indication, and set parameters for each emitted electron beam B, or set the emission time of the electron beam B, and establish a relationship between the parameters of the emitted electron beam B and the emission time for setting. The information display device 6 can be a known device such as a liquid crystal display, a CRT (Cathode-Ray Tube) display, an organic EL (Electroluminescence) display, or an LED (Light Emitting Diode) display.

[0058] The electron gun 1C of the third embodiment can set the parameters of the electron beam B to be emitted after referring to information from the partner device E. Therefore, in addition to the effects that the electron gun 1 of the first and second embodiments can achieve, it can also achieve the effect of setting parameters in more detail.

[0059] (Fourth Embodiment of Electron Gun) The fourth embodiment of the electron gun 1D will now be described with reference to FIG6. FIG6 is a schematic diagram showing the fourth embodiment of the electron gun 1D and the partner device E equipped with the electron gun 1D.

[0060] The fourth embodiment of the electron gun 1D is a component that is controlled by the control unit 5 and the partner device E. This is different from the first to third embodiments of the electron guns 1A to 1C. However, all other aspects are the same as the first and third embodiments of the electron guns 1A to 1C.

[0061] The control unit 5 of the electron gun 1D in the fourth embodiment not only sets the parameters of the electron beam B emitted from the electron gun 1D and controls the constituent components of the electron gun 1D according to the settings, but also controls the constituent components of the partner device E in a manner that establishes a relationship with the set parameters. Therefore, in the control example based on the parameters set by the control unit 5, the following controls can be performed, for example: (1) When the partner device E has an electron beam size adjustment device such as an electromagnetic lens or an aperture, the control unit 5 can control the electron beam size adjustment device of the partner device E as needed while controlling the size of the electron beam B. (2) When the partner device E has an electron beam shape adjustment device such as an electromagnetic lens or an aperture, the control unit 5 can control the electron beam shape adjustment device of the partner device E as needed while controlling the shape of the electron beam B. (3) When the partner device E has a mechanical shutter, the control unit 5 can control the mechanical shutter of the partner device E as needed while controlling the emission time of the electron beam B. (4) When the partner device E has an energy filter, the control unit 5 can control the energy filter of the partner device E as needed while controlling the emission rate of the electron beam B. (5) When a continuous electron beam B is emitted by the control of the electron guns 1A to 1C, the deflection velocity of the electron beam B is set according to the partner device E. Therefore, unlike the pulsed electron beam B, it is not possible to set the parameter for the emission time of the electron beam B. Therefore, it is not possible to control the duration of the irradiation of the same position of the irradiation area R by the electron beam B. On the other hand, when the control unit 5 controls the electron beam deflection device 10 in a manner related to the emission time, the duration of the irradiation of the same position of the irradiation area R by controlling the deflection velocity of the electron beam deflection device 10 can be controlled. In addition, when the control unit 5 controls the deflection velocity of the electron beam deflection device 10, it can calculate the deflection velocity of the electron beam deflection device 10 when setting the emission time of the electron beam B. (6) As shown in Figure 2, the electron beam deflection device 10 of the partner device E typically scans the incoming electron beam B in a linear pattern. On the other hand, when the control unit 5 controls the electron beam deflection device 10 in a manner that establishes a relationship with the sequence of the emitted electron beam B or the emission time of the emitted electron beam B, it can rotate at a desired position on a line, or it can irradiate the desired location with the electron beam B having the desired parameters in a desired order for the irradiation area R.

[0062] The electron gun 1D of the fourth embodiment can also control the constituent components of the partner device E. Therefore, in addition to achieving the functions of the electron guns 1A to 1C of the first to third embodiments, it can also achieve the function of increasing the number of options for the control method of the set parameters.

[0063] (Example of an electron beam application device) The electron beam application device E, which is equipped with an electron gun 1 (1A to 1D), can include known devices equipped with electron guns. Examples include free electron laser accelerators, electron microscopes, electron beam holography devices, electron beam patterning devices, electron beam diffraction devices, electron beam inspection devices, electron beam metal lamination devices, electron beam lithography devices, electron beam processing devices, electron beam hardening devices, electron beam sterilization devices, electron beam disinfection devices, plasma generation devices, atomic element generation devices, rotating polarized electron beam generation devices, cathodic emission devices, and inverse photon radiography devices.

[0064] The electron beam application device equipped with electron gun 1 disclosed in this case can achieve the following effects: (1) Regardless of the type of electron beam application device, the parameters of the emitted electron beam B can be set by the components on the side of the electron gun 1. Therefore, the convenience of the electron beam application device is improved. (2) In the case of an electron microscope, the sample may become charged. By irradiating an area different from the location to be photographed with an electron beam whose parameters such as the intensity and size of electron beam B are set, the charge on the sample can be removed. (3) In the case of an electron microscope, by increasing the acceleration energy of electron beam B, electrons can reach a deeper position in the sample. In addition, by controlling the intensity of electron beam B, the unevenness of the sample can be made more distinct, and structures that could not be observed before can be seen. (4) In the case of an electron microscope, by irradiating areas with weaker signals with a stronger electron beam B and areas with excessively strong signals with a weaker electron beam B, signals that would otherwise exceed the detector's detection range in the electron beam B can be included within that range. (5) In the case of an electron beam metal lamination molding device (3D printer), there may be situations where the substrate of the laminated metal needs to be heated. Controls can be made to strengthen the electron beam B only in the areas to be heated, increase the emission time of the electron beam B, or increase the size of the electron beam B. (6) In the case of an electron beam inspection device, inspections can be carried out efficiently by selecting the areas to be inspected or by setting the inspection conditions, thereby improving the inspection processing capacity.

[0065] (Example of electron beam emission method) An example of an electron beam emission method (hereinafter referred to as "emission method") is performed using the electron gun 1 of the first to fourth examples or an electron beam application device equipped with the electron gun 1 of the first to fourth examples.

[0066] The emission method of the embodiment includes an electron beam emission step in which an excitation light L from a light source 2 is irradiated onto a photocathode 3, and an electron beam B is formed by drawing out electrons generated in the photocathode 3 based on the light received by the excitation light L through an electric field formed between the photocathode 3 and the anode 4. The control unit 5 of the electron gun 1 can (1) set the number of times the electron beam B is emitted and set parameters according to each emitted electron beam B, or (2) set the emission time of the electron beam B and establish a relationship between the parameters of the emitted electron beam B and the emission time. Furthermore, in the electron beam emission step, the control unit 5 controls the constituent components of the electron gun 1 in such a way that the emitted electron beam B becomes the set parameters, and can also arbitrarily control the constituent components of the partner device E.

[0067] (Example 1 of the control unit 5 in the emission method) When the control unit 5 (1) sets the number of times the electron beam B is emitted and sets parameters for each emitted electron beam, the parameters may include at least one selected from, for example, the intensity of the electron beam, the magnitude of the acceleration energy of the electron beam, the size of the electron beam, the shape of the electron beam, the emission time of the electron beam, and the emission rate of the electron beam. The control unit 5 can control the parameters of all electron beams to be the same when emitting the set number of electron beams, or it can control at least one parameter to be different from one selected from other parameters. In addition, as described in the embodiment of the electron gun 1, the control unit 5 can control only the constituent components on the electron gun 1 side, or it can control the constituent components of the partner device E. Specific examples of control have been described in the embodiment of the electron gun 1, so detailed descriptions are omitted.

[0068] (Example 2 of the implementation of the control unit 5 in the emission method) When the control unit 5 (2) sets the emission time of the electron beam B and sets the parameters of the emitted electron beam B in relation to the emission time, the parameters may include at least one selected from, for example, the intensity of the electron beam, the magnitude of the acceleration energy of the electron beam, the size of the electron beam, the shape of the electron beam, and the emissivity of the electron beam. The control unit 5 can be controlled to set the emission time of the electron beam B to be emitted and make the parameters of the emitted electron beam B the same, or it can be controlled to include the time of electron beams B with different emission parameters.

[0069] Although the following embodiments are disclosed to specifically illustrate the embodiments disclosed in this case, these embodiments are merely illustrative and are not intended to limit or restrict the scope of the invention disclosed in this case. [Examples]

[0070] <Example 1> [Fabrication of Electron Gun 1】 A laser light source (iBeamSmart manufactured by Toptica) was used on the light source 2. The photocathode 3 was fabricated using the known method described in Daiki SATO et al. 2016 Jpn. J. Appl. Phys. 55 05FH05. The EA treatment on the surface of the photocathode was performed using a known method. The control unit 5 was programmed to set the number of times the electron beam B was emitted, and the electron beam parameters were set according to each emitted electron beam B.

[0071] <Example 2> [Fabrication of Electron Beam Application Apparatus (SEM)] The electron gun portion of a commercially available SEM was replaced with the fabricated electron gun 1. Furthermore, the specifications of the commercially available SEM include an electron gun using a cold-type electric field emission electron source (CFE) and a deflection coil as an electron beam deflection device 10. The maximum accelerating voltage of the electron beam is 30 kV, allowing for observations up to 1 million times magnification.

[0072] [Electron Beam Irradiation Method] <Example 3> A sample with a textured surface was prepared and placed on an SEM. The number of electron beam emanations was set by the control unit 5, taking into account the magnification, the size of the electron beam B, and the irradiation area. The parameters were set using the intensity of the electron beam B (zero intensity (no excitation light L irradiation) or a certain intensity), and the number of emanations for the portion with zero intensity was considered in order to form a PeS logo on the sample. Next, the components of the electron gun 1 were controlled using the set parameters, and the electron beam B was used to irradiate the sample for imaging. The imaging result is shown in Figure 7A. As shown in Figure 7A, the portion irradiated by the electron beam B is available for imaging of the sample, and the textured and non-textured portions are clearly visible. Furthermore, the portion with zero intensity of the electron beam B is not available for imaging of the sample and is therefore black. As shown in Figure 7A, the black PeS marking confirms that the electron beam B with the desired electron beam parameters can be irradiated onto the desired area of ​​the sample using the components on the electron gun 1 side. Furthermore, when the parameters of the electron beam B are set to prevent irradiation of a portion of the irradiation area R as shown in Embodiment 3, the degradation of the photocathode 3 can be prevented compared to continuous irradiation with the same intensity of electron beam B, and the lifespan of the photocathode 3 can also be extended.

[0073] <Example 4> Next, based on the imaging results shown in FIG7A on the information display device, the imaging area (irradiation area) was set to allow for magnified imaging of the portion with a raised or recessed pattern, and the number of times the electron beam B was emitted was set by the control unit 5. Furthermore, in Example 3, although the parameters of the electron beam B were set in a way that could form a PeS mark, in Example 4, the irradiation area where the intensity of the electron beam B was zero was made into a roughly semi-circular shape, taking into account the order of the number of emanations, and the parameters were set accordingly. FIG7B shows the imaging results. As shown in FIG7B, the portion irradiated by the electron beam B is suitable for imaging the raised or recessed portion of the sample after magnification, and the portion where the intensity of the electron beam B was zero was made into a roughly semi-circular shape. In the example shown in FIG7B, although the parameters are only two variations in the intensity of the electron beam B, the desired location on the sample can be irradiated with an electron beam B having the desired parameters. Therefore, by referring to the information from the partner device E, it was confirmed that the parameters can be set in more detail. [Industrial Applicability]

[0074] By using the electron gun, electron beam application device, and electron beam emission method disclosed in this case, it is possible to configure the electron gun to irradiate an electron beam with desired electron beam parameters at a desired location on the irradiated object using only the components on the electron gun side. Therefore, it is extremely useful for manufacturers dealing with electron guns. [Simplified Explanation of the Diagram]

[0017] [Figure 1] Figure 1 is a schematic diagram showing the electron gun 1A of the first embodiment and the partner device E equipped with the electron gun 1A. [Figure 2] Figure 2 is a schematic diagram showing the control unit 5 of the electron gun 1A. [Figure 3] Figure 3 is a schematic diagram showing the control unit 5 controlling the set electron beam parameters. [Figure 4] Figure 4 is a partially enlarged diagram showing the photocathode 3 of the electron gun 1B of the second embodiment. [Figure 5] Figure 5 is a schematic diagram showing the electron gun 1C of the third embodiment and the partner device E equipped with the electron gun 1C. [Figure 6] Figure 6 is a schematic diagram showing the electron gun 1D of the fourth embodiment and the partner device E equipped with the electron gun 1D. [Figure 7] Figure 7A is a surrogate photograph, a SEM photograph taken in Embodiment 3. Figure 7B is a surrogate photograph, a SEM photograph taken in Embodiment 4.

Claims

1. An electron gun, comprising: light source; A photocathode generates electrons that can be emitted based on light received from the aforementioned light source; The anode is capable of forming an electric field with the aforementioned photocathode, and drawing out the aforementioned emissible electrons through the formed electric field to form an electron beam; and the control unit; the aforementioned control unit sets the number of pulsed electron beams emitted when irradiating the irradiation area, and sets electron beam parameters according to each emitted pulsed electron beam. The aforementioned electron beam parameters include at least one selected from electron beam intensity, electron beam acceleration energy, electron beam size, electron beam shape, electron beam emission time, and electron beam emissivity. Alternatively, the control unit sets the continuous electron beam emission time required to scan the irradiation area, and establishes a correlation between the electron beam parameters of the continuous electron beams before emission and the aforementioned emission time. The aforementioned electron beam parameters include at least one selected from electron beam intensity, electron beam acceleration energy, electron beam size, electron beam shape, and electron beam emissivity.

2. The electron gun as described in claim 1, wherein, The aforementioned number of emission times is two or more, and the aforementioned control unit controls that when emitting the aforementioned pulsed electron beam a set number of times, at least one electron beam parameter is different from one selected from other electron beam parameters.

3. The electron gun as described in claim 1, wherein, The aforementioned control unit controls the emission of the aforementioned continuous electron beams at the set emission time, including the time for emitting electron beams with different electron beam parameters.

4. The electron gun described in any of claims 1 to 3 irradiates excitation light from a light source at two or more different locations of the aforementioned photocathode to extract two or more electron beams from the aforementioned photocathode.

5. An electron beam application device comprising the electron gun described in any one of claims 1 to 3, wherein the aforementioned electron beam application device is a free electron laser accelerator; an electron microscope; an electron beam holography device; an electron beam patterning device; an electron beam diffraction device; an electron beam inspection device; an electron beam metal lamination molding device; an electron beam lithography device; an electron beam processing device; an electron beam hardening device; an electron beam sterilization device; an electron beam disinfection device; a plasma generation device; an atomic element generation device; a rotating polarized electron beam generation device; a cathodic emission device; or a reverse photon radiography device.

6. A method for emitting an electron beam, wherein the electron beam is emitted from an electron gun, the electron gun comprising: light source; A photocathode generates electrons that can be emitted based on light received from the aforementioned light source; The anode is configured to generate an electric field with the aforementioned photocathode, thereby drawing out the aforementioned emissible electrons to form an electron beam; and a control unit. The control unit sets the number of pulsed electron beam emissions required during irradiation of the irradiation area, and sets electron beam parameters for each emitted pulsed electron beam. These electron beam parameters include at least one selected from electron beam intensity, electron beam acceleration energy, electron beam size, electron beam shape, electron beam emission time, and electron beam emissivity. Alternatively, it sets the continuous electron beam emission time required to scan the irradiation area, and establishes a correlation between the electron beam parameters of the preceding continuous electron beams and the emission time. These electron beam parameters may include at least one selected from electron beam intensity, electron beam acceleration energy, electron beam size, electron beam shape, and electron beam emissivity. The emission method includes an electron beam emission step, in which excitation light from the aforementioned light source is irradiated onto the aforementioned photocathode, and the electrons generated in the aforementioned photocathode according to the exposure to the excitation light are extracted by an electric field formed between the aforementioned photocathode and the aforementioned anode to form an electron beam; the aforementioned control unit controls the emitted electron beam to have set electron beam parameters in the electron beam emission step.

7. The electron beam emission method as described in claim 6, wherein, The aforementioned number of emission times is two or more, and the aforementioned control unit controls that when emitting the aforementioned pulsed electron beam a set number of times, at least one electron beam parameter is different from one selected from other electron beam parameters.

8. The electron beam emission method as described in claim 6, wherein, The aforementioned control unit controls the emission of the aforementioned continuous electron beams at the set emission time, including the time for emitting electron beams with different electron beam parameters.

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