WO2014185060A1 - Charged particle optical lens device and charged particle optical lens device control method - Google Patents

Charged particle optical lens device and charged particle optical lens device control method Download PDF

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Publication number
WO2014185060A1
WO2014185060A1 PCT/JP2014/002524 JP2014002524W WO2014185060A1 WO 2014185060 A1 WO2014185060 A1 WO 2014185060A1 JP 2014002524 W JP2014002524 W JP 2014002524W WO 2014185060 A1 WO2014185060 A1 WO 2014185060A1
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Prior art keywords
charged particle
particle optical
optical lens
electromagnetic field
voltage
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PCT/JP2014/002524
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French (fr)
Japanese (ja)
Inventor
建次郎 木村
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国立大学法人神戸大学
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Priority to JP2015516916A priority Critical patent/JPWO2014185060A1/en
Publication of WO2014185060A1 publication Critical patent/WO2014185060A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement, ion-optical arrangement
    • H01J37/10—Lenses
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/04—Means for controlling the discharge
    • H01J2237/049—Focusing means
    • H01J2237/0492—Lens systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/10—Lenses
    • H01J2237/12—Lenses electrostatic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/10—Lenses
    • H01J2237/14—Lenses magnetic

Definitions

  • the present invention relates to a charged particle optical lens apparatus and a control method for the charged particle optical lens apparatus, and more particularly to a charged particle optical lens used in a charged particle beam optical apparatus using an electrostatic lens such as a charged particle microscope and a charged particle beam exposure apparatus.
  • the present invention relates to an apparatus and a method for controlling a charged particle optical lens apparatus.
  • charged particle beam irradiation apparatuses using charged particle beams have been used in electron microscopes, electron beam exposure apparatuses, and ion microscopes.
  • a charged particle optical lens for focusing a charged particle beam is provided in the same manner as a convex lens for focusing light in an optical microscope.
  • the charged particle optical lens is classified into a magnetic field application type magnetic lens and an electric field application type electrostatic lens.
  • An electrostatic lens is a ring-shaped electrode having conductivity. By applying a predetermined voltage to this electrode, an electric field distribution is generated and the trajectory of the charged particle beam passing through the ring-shaped electrode is bent. It is configured to focus on a predetermined position (for example, the surface of the observation sample).
  • a predetermined position for example, the surface of the observation sample.
  • the shape of the sample surface is observed with a focused charged particle beam.
  • a predetermined pattern is drawn on a sample surface by a focused charged particle beam (see, for example, Patent Document 1).
  • spherical aberration indicates that the focal length differs between a charged particle beam passing through the center of the lens and a charged particle beam passing through the end of the lens. This aberration also occurs in an optical microscope.
  • an optical microscope by arranging a convex lens and a concave lens in combination, the aberration generated in the convex lens is corrected by the concave lens, thereby correcting the aberration as the entire optical microscope.
  • an electrostatic lens or a magnetic lens in which a plurality of ring electrodes are arranged in multiple stages is used as a lens.
  • a lens for use in a charged particle microscope only a convex lens can be basically produced using a rotating lens. For this reason, the generation of aberration is suppressed by forming an electrostatic lens having a lens diameter as large as possible and using a paraxial light beam that is a charged particle beam passing through the vicinity of the optical axis of the electrostatic lens. In this case, it means that it is difficult to reduce the size of the lens.
  • an object of the present invention is to provide a charged particle optical lens device capable of generating a non-aberrated charged particle beam and a control method for the charged particle optical lens device.
  • a charged particle optical lens device includes a charged particle optical lens group including a plurality of charged particle optical lenses arranged in multiple stages, and the plurality of charged particle optical lenses. And an electric signal distribution device that applies a voltage or current reflecting the calculation result of the electromagnetic field simulation, and the electromagnetic field simulation has a lens diameter larger than that of the plurality of charged particle optical lenses. Is a simulation for calculating an electrostatic potential distribution or a magnetic potential distribution created at each position of the plurality of charged particle optical lenses.
  • the charged particle optical lens device may further include a processing device for performing the electromagnetic field simulation.
  • the charged particle optical lens is an electrode having an annular shape
  • the electromagnetic field simulation is a simulation for calculating an electrostatic potential distribution
  • the electric signal distribution device includes the electromagnetic field simulation on the electrode.
  • An electric field may be generated by applying a voltage reflecting the result of the calculation.
  • the charged particle optical lens is an electromagnet arranged in a ring shape
  • the electromagnetic field simulation is a simulation for calculating a magnetic potential distribution
  • the electric signal distribution device is configured to transmit the electromagnetic field simulation to the electromagnet.
  • a magnetic field may be generated by applying a current reflecting the calculation result.
  • a charged particle optical lens device with good convergence can be provided by adjusting the current applied to the charged particle optical lens from the result of the magnetic potential distribution obtained by the simulation.
  • a charged particle optical lens control method is to obtain a voltage or current value to be applied to a plurality of charged particle optical lenses arranged in multiple stages. Performing an electromagnetic field simulation for calculating an electrostatic potential distribution or a magnetic potential distribution that a charged particle optical lens having a lens diameter larger than that of the plurality of charged particle optical lenses creates at each position of the plurality of charged particle optical lenses; Applying a voltage or current reflecting the calculation result of the electromagnetic field simulation to each of the plurality of charged particle optical lenses by the electric signal distribution device.
  • the voltage or current applied to the plurality of charged particle optical lenses may be determined by the past calculation result of the electromagnetic field simulation. You may select from the value of the said voltage or electric current applied to the charged particle optical lens.
  • the voltage or current applied to the plurality of charged particle optical lenses is the voltage or current applied to the charged particle optical lens. Before being applied, it may be calculated by the electromagnetic field simulation each time.
  • a charged particle optical lens device capable of generating an aberration-free charged particle beam and a control method for the charged particle optical lens device.
  • FIG. 1 is a schematic diagram showing the configuration of a charged particle optical lens device.
  • FIG. 2 is a diagram illustrating an example of a lens group having a plurality of annular electrodes.
  • FIG. 3 is a flowchart for explaining a control procedure of the charged particle optical lens device.
  • FIG. 4 is a diagram illustrating a target region indicating a potential distribution obtained by electromagnetic field simulation.
  • FIG. 5A is a diagram showing a more specific configuration of the charged particle optical lens device according to the present embodiment.
  • FIG. 5B is data showing the voltage applied to each annular electrode obtained by electromagnetic field simulation.
  • FIG. 6A is a diagram illustrating a potential distribution and a charged particle beam trajectory when a voltage is applied to the Einzel lens.
  • FIG. 6B is a diagram showing a potential distribution and a charged particle beam trajectory when a voltage is applied to 14 annular electrodes.
  • FIG. 6C is a diagram showing a potential distribution and charged particle beam trajectories when a voltage is applied to 47 annular electrodes.
  • FIG. 7A is a diagram illustrating a configuration of a charged particle optical lens device.
  • FIG. 7B is a diagram showing a potential distribution when a normal Einzel lens is used.
  • FIG. 7C is a diagram showing charged particle beams generated in the charged particle optical lens device.
  • FIG. 7D is a diagram showing charged particle beams generated when the Einzel lens of FIG. 7B is used.
  • FIG. 8A is a diagram illustrating a configuration of a charged particle optical lens device.
  • FIG. 8A is a diagram illustrating a configuration of a charged particle optical lens device.
  • FIG. 8B is a diagram illustrating an electrostatic potential distribution when a virtual large Einzel lens is used.
  • FIG. 8C is a diagram showing charged particle beams generated in the charged particle optical lens device.
  • FIG. 8D is a diagram showing charged particle beams generated when the Einzel lens of FIG. 8B is used.
  • a paraxial ray refers to a ray whose path passes through the vicinity of the optical axis, and whose basic equation for the trajectory is linear.
  • spherical aberration is caused by the light beam (charged particle beam) passing through the center of the lens and the light beam (charged particle beam) passing through the end of the lens from the center of the lens. It means that the distance to the focusing position of the light beam (charged particle beam) and the focal length are different.
  • Equation 1 If the lens is a rotating body, (Equation 1) becomes the following (Equation 2).
  • the paraxial light beam refers to a light beam that has a small angle with respect to the optical axis of the optical system and whose path passes through the vicinity of the optical axis.
  • the paraxial approximation described above does not hold near the end of the lens with a large r (near the electrode). Therefore, when a large lens is prepared and light rays near the optical axis of the large lens are used, the aberration is reduced. In addition, the larger the lens, the smaller the aberration.
  • a charged particle optical lens device and a method for controlling the charged particle optical lens device according to the present invention which can generate an aberrated charged particle beam that is ideal for a charged particle beam, will be described below.
  • FIG. 1 is a schematic diagram illustrating a configuration of a charged particle optical lens device according to the present embodiment.
  • the charged particle optical lens device 1 includes a charged particle optical lens group including a plurality of annular electrodes 24 provided in a vacuum chamber 10, and a charged particle beam generator. 21, a voltage application unit 12, and a calculation unit 14.
  • the annular electrode 24 corresponds to the charged particle optical lens in the present invention.
  • the voltage application unit 12 corresponds to the electric signal application device in the present invention.
  • the charged particle beam optical lens device according to the embodiment of the present invention is arranged in the vacuum chamber 10 by arranging a charged particle optical lens group including a plurality of annular electrodes 24 in addition to the charged particle beam generator 21.
  • the charged particle beam irradiation apparatus using
  • a Wehnelt electrode 25 and an acceleration electrode are provided inside the vacuum chamber 10. 22 and lens electrodes 26a, 26b and 26c.
  • the acceleration electrode 22 is continuous with the lens electrode 26a.
  • a measurement sample 16 is disposed in the vacuum chamber 10.
  • the charged particle beam generation unit 21 is configured by a so-called charged particle source that generates a charged particle beam.
  • the charged particle beam generated by the charged particle beam generation unit 21 passes through the annular electrode 24 and is irradiated to the sample 16.
  • the annular electrode 24 has a donut shape, that is, an annular shape, and is made of, for example, a nonmagnetic metal such as aluminum or SUS. A plurality of the annular electrodes 24 are laminated to constitute a charged particle optical lens group as a whole. Further, insulators are provided and insulated between the laminated annular electrodes 24.
  • FIG. 2 is a diagram showing an example of a charged particle optical lens group having a plurality of annular electrodes 24.
  • the charged particle optical lens group shown in FIG. 2 has 20 annular electrodes 24.
  • An insulator is provided between each annular electrode 24, and each annular electrode 24 is insulated.
  • FIG. 1 a cross section obtained by cutting a configuration in which a plurality of annular electrodes 24 in the left-right direction toward the paper surface in FIG. 1 passes through the axis of the annular electrode 24. It is shown in the figure. An insulator is provided between the plurality of annular electrodes 24, but is not shown in FIG.
  • the voltage application unit 12 generates a voltage as an electric signal to be applied to the annular electrode 24.
  • the voltage application unit 12 is configured by, for example, a D / A (digital / analog) converter.
  • the voltage application unit 12 corresponds to the electrical signal distribution device in the present invention.
  • the calculation unit 14 is constituted by a CPU, for example, and performs electromagnetic field simulation for obtaining a value of an electric signal (voltage) to be applied to the annular electrode 24.
  • the electromagnetic field simulation will be described in detail later.
  • the calculating part 14 is corresponded to the processing apparatus in this invention.
  • FIG. 1 also shows a Wehnelt electrode 25 for configuring a charged particle optical lens (virtual large lens) having a diameter larger than the diameter of the virtual annular electrode 24 used for electromagnetic field simulation in addition to the above-described configuration, and acceleration.
  • the electrode 22 and the lens electrodes 26a, 26b and 26c are shown.
  • the Wehnelt electrode 25, the acceleration electrode 22, and the lens electrodes 26a, 26b, and 26c are virtual electrodes assuming a Wehnelt electrode, an acceleration electrode, and an Einzel lens.
  • FIG. 3 is a flowchart for explaining a control procedure of the charged particle optical lens device 1 according to the present embodiment.
  • step S12 the electrostatic potential distribution at the position of the annular electrode (small lens) 24 generated by the virtual large lens is calculated (step S12). That is, when it is assumed that a voltage is applied to the Wehnelt electrode 25, the acceleration electrode 22, and the lens electrodes 26a, 26b, and 26c, which are virtual electrodes, the electric field distribution generated at the position of the annular electrode 24 is calculated by electromagnetic field simulation. . Thereafter, a voltage is applied to the annular electrode 24 by the voltage application unit 12 so that the same electrostatic potential as that calculated by the electromagnetic field simulation is generated at the position of the annular electrode 24 (step S14).
  • the same charged particle beam as when a voltage is applied to the Wehnelt electrode 25, the acceleration electrode 22, and the lens electrodes 26a, 26b, and 26c, which are virtual electrodes, can be realized (step S16).
  • the electromagnetic field simulation is not limited to the simulation for obtaining the electrostatic potential distribution, but may be a simulation for obtaining the magnetic potential distribution.
  • an electromagnet may be used as the charged particle optical lens group, and a current reflecting the calculation result of the electromagnetic field simulation may be applied to the electromagnet.
  • the voltage application unit 12 may output a current as an electric signal to be applied to the electromagnet.
  • FIG. 4 is a diagram illustrating a region that is a target of the electrostatic potential distribution obtained by the electromagnetic field simulation according to the present embodiment.
  • the results obtained by the following electromagnetic field simulation show the electrostatic potential distribution in a partial region 30 of the charged particle optical lens device 1 shown in FIG. 1, as shown in FIG. That is, the region 30 is a region including a region from the central axis of the annular electrode 24 to one end in the radial direction in FIG.
  • the Wehnelt electrode 25, the acceleration electrode 22, and the lens electrodes 26a, 26b, and 26c constituting the virtual large lens may be simply referred to as a lens hereinafter.
  • the annular electrode 24 may be simply referred to as a lens.
  • the principle of the charged particle optical lens device 1 is as described above. That is, a charged particle optical lens group (a plurality of annular electrodes 24) having the same direction as the orbital direction (irradiation direction) of the charged particle beam is arranged. In order to determine an electric signal (voltage) applied to each of the annular electrodes 24 constituting the charged particle optical lens group, a charged particle optical lens (virtual large lens) having a diameter larger than the diameter of the annular electrode 24 is virtually used. Assuming that the Wehnelt electrode 25, the accelerating electrode 22, and the lens electrodes 26a, 26b, and 26c exist, the electrostatic potential generated at the positions of the plurality of annular electrodes 24 is calculated. The electric signal (voltage) obtained by the calculation is actually applied to the plurality of annular electrodes 24. Thereby, the charged particle optical lens device 1 generates the same charged particle beam as the paraxial light beam obtained when a virtual large lens is used.
  • FIG. 5A is a diagram showing a more specific configuration of the charged particle optical lens device according to the present embodiment.
  • FIG. 5B is data showing the voltage applied to each annular electrode 24 obtained by electromagnetic field simulation.
  • the basic configuration of the charged particle optical lens device 1 is the same as that of the charged particle optical lens device 1 shown in FIG.
  • FIG. 5A shows in detail the configuration arranged outside the vacuum chamber 10, particularly the configuration of the calculation unit 14.
  • a charged particle beam generation unit 21, a Wehnelt electrode 25, an acceleration electrode 22, and a plurality of annular electrodes 24 are provided in the vacuum chamber 10.
  • the sample 16 is disposed on the XYZ stage 17.
  • a secondary electron detector 23 for detecting secondary electrons is disposed at a position spaced apart from the plurality of annular electrodes 24 on the side where the sample 16 is disposed.
  • the lens electrodes 26a, 26b, and 26c are virtual charged particle optical lenses (virtual large lenses) and are therefore shown outside the vacuum chamber 10.
  • a voltage application unit 12 a secondary electron detector output amplifier 18, an XYZ stage preamplifier 19, and a calculation unit 14 are arranged outside the vacuum chamber 10.
  • the configuration of the voltage application unit 12 is the same as that shown in FIG.
  • the calculation unit 14 includes a simulation unit 31, a memory 32, a multi-channel DA converter 34, an AD converter 36, and a DA converter 38.
  • the boundary condition Vb is a voltage applied to the lens electrodes 26a, 26b and 26c of the virtual large lens.
  • the voltage value calculated in the simulation unit 31 is stored as data. As shown in FIG. 5B, in this data, each position and voltage value of the plurality of annular electrodes 24 are associated with each other. Based on this data, a predetermined voltage is applied to the annular electrode 24.
  • the multi-channel DA converter 34 supplies information on the voltage applied to the annular electrode 24 to the voltage application unit 12 based on the data stored in the memory 32.
  • the voltage application unit 12 may calculate the voltage value applied to the annular electrode 24 by electromagnetic field simulation each time, or store a plurality of electromagnetic field simulation data used in the past in the memory 32. You may choose from them.
  • the AD converter 36 is connected to the secondary electron detector output amplifier 18, converts the secondary electron information output from the secondary electron detector output amplifier 18 into digital information, and obtains position information irradiated with the electron beam. .
  • the DA converter 38 is connected to the XYZ stage preamplifier 19 and moves the position of the sample 16 by applying an analog voltage signal to the XYZ stage 17.
  • FIGS. 6A to 6C are diagrams showing the relationship between the number of the annular electrodes 24 constituting the lens group and the reproduced charged particle trajectory.
  • FIG. 6A is a diagram showing an electrostatic potential distribution and a trajectory of a charged particle beam when a voltage is applied to an Einzel lens.
  • FIG. 6B is a diagram showing electrostatic potential distributions and charged particle beam trajectories when 14 annular electrodes 24 are provided and a voltage is applied to the 14 annular electrodes 24.
  • the applied voltage to the annular electrode 24 at this time shows the same value as the electrostatic potential generated at the position of the annular electrode 24 in the electrostatic potential distribution when the voltage is applied to the Einzel lens shown in FIG. 6A.
  • FIG. 6C is a diagram illustrating an electrostatic potential distribution and a charged particle beam trajectory when 47 annular electrodes 24 are provided and a voltage is applied to the 47 annular electrodes 24.
  • the applied voltage to the annular electrode 24 at this time shows the same value as the electrostatic potential generated at the position of the annular electrode 24 in the electrostatic potential distribution when the voltage is applied to the Einzel lens shown in FIG. 6A. .
  • the region inside the ring of the annular electrode 24 has the same electrostatic potential distribution as in FIG. 6A. 6A to 6C, the position of 0 cm in the vertical axis direction indicates the center position of the Einzel lens or the annular electrode 24.
  • a charged particle beam showing the same trajectory as the charged particle beam of the Einzel lens in FIG. 6A is generated in a central region (about 0 to 0.3 cm in the vertical axis direction) of the annular electrode 24 in FIG. 6C. ing.
  • the position of 30 cm in the horizontal axis direction indicates the focal point P of the charged particle beam.
  • the focal point P of the charged particle beam is a position on the horizontal axis 28 cm. Comparing FIG. 6B and FIG. 6C, since the number of the annular electrodes 24 is not sufficient in FIG. 6B, the position of the focal point P of the charged particle beam in the Einzel lens shown in FIG. 6A is not reproduced. Since the number of the annular electrodes 24 is sufficiently increased, the focal point P of the charged particle beam asymptotically approaches the same position as the focal point P of the charged particle beam in the Einzel lens of FIG. 6A.
  • FIGS. 7A to 7D show examples of generation of charged particle beams of the virtual large lens when a voltage is applied to the annular electrode 24 assuming that the virtual large lens exists.
  • 7A to 7D show the results of electromagnetic field simulation when the diameter of the annular electrode is 1/20 with respect to the diameter of the virtual large lens.
  • FIG. 7A is a configuration diagram of the charged particle optical lens device
  • FIG. 7B shows an electrostatic potential distribution when a virtual large Einzel lens is used.
  • FIG. 7C shows a charged particle beam generated in the charged particle optical lens device 1 shown in FIG. 7A.
  • FIG. 7D shows a charged particle beam generated when the Einzel lens shown in FIG. 7B is used.
  • the charged particle optical apparatus using the charged particle optical lens apparatus 1 according to the present embodiment it is possible to perform observation or drawing with good convergence without aberration, without correcting the focal position.
  • the charged particle optical device using the charged particle optical lens device 1 according to the present embodiment it is not necessary to actually use a lens having a large aperture, so that the size of the device can be reduced.
  • FIGS. 8A to 8D show examples of generation of charged particle beams when a voltage is applied to the annular electrode 24 assuming that a lens having a virtually large lens diameter exists.
  • 8A to 8D show the results of electromagnetic field simulation when the diameter of the annular electrode is 1/100 with respect to the diameter of the virtual large lens.
  • FIG. 8A shows a configuration diagram of the charged particle optical lens device
  • FIG. 8B shows an electrostatic potential distribution when a virtual large Einzel lens is used.
  • FIG. 8C shows a charged particle beam generated in the charged particle optical lens device 1 shown in FIG. 8A.
  • FIG. 8D shows a charged particle beam generated when the Einzel lens shown in FIG. 8B is used.
  • Comparing FIG. 8C and FIG. 8D shows that the same charged particle beam is generated. Therefore, according to the charged particle optical lens device according to the present embodiment, it is understood that the same charged particle beam as that obtained when a large aperture lens is used can be obtained without using a large aperture lens. .
  • the charged particle optical lens device 1 can provide a charged particle optical device free from aberrations without correcting the focal position. Further, in the charged particle optical device using the charged particle optical lens device 1, the size of the device can be reduced.
  • the charged particle optical lens device and the control method of the charged particle optical lens device according to the present embodiment even if the large aperture lens is not actually used, it is the same as the case where the large aperture lens is used. Can be obtained. Therefore, in the charged particle optical device using the charged particle optical lens device, it is possible to obtain a charged particle beam having no aberration, not to correct aberrations, and to perform microscopic observation and drawing with high convergence. .
  • the size of the device can be reduced. Furthermore, the focusing property of the charged particle optical device can be improved as the diameter of the lens having a virtual large diameter with respect to the diameter of the annular electrode is larger.
  • the voltage applied to the plurality of annular electrodes 24 is applied to the annular electrode 24 according to the calculation result of the past electromagnetic field simulation as described above. It may be selected from a list of set voltage distributions, or may be calculated by electromagnetic field simulation each time before a voltage is applied to the annular electrode 24.
  • the list may be selected by referring to a common database using the Internet or the like, and each charged particle optical device includes a memory device or the like. Alternatively, the voltage distribution list may be held.
  • the charged particle optical lens is an electrode having an annular shape
  • the electromagnetic field simulation is a simulation for calculating an electrostatic potential distribution
  • the voltage application unit 12 is connected to the annular electrode 24.
  • the optical lens device according to the embodiment described above the optical lens is an annularly arranged electromagnet, and the electromagnetic field is described.
  • the simulation is a simulation for calculating a magnetic potential distribution
  • the voltage application unit 12 may apply a current reflecting the calculation result of the electromagnetic field simulation to the electromagnet.
  • the present invention is not limited to the above-described embodiment.
  • Forms obtained by subjecting the embodiments to modifications conceivable by those skilled in the art, and other forms realized by arbitrarily combining components in the plurality of embodiments are also included in the present invention.
  • the configuration in which the charged particle optical lens device is used in a charged particle microscope has been described.
  • the charged particle optical lens device is used in other charged particle optical devices such as a charged particle beam drawing device. Also good.
  • another processing unit such as the voltage application unit 12 or another computer may execute the processing executed by a specific processing unit such as the calculation unit 14. Further, the order of executing the processes in the charged particle optical lens device may be changed, or a plurality of processes may be executed in parallel.
  • the steps in the method for controlling the charged particle optical lens device described above may be executed by a computer. Moreover, you may implement
  • the control method of the charged particle optical lens device and the charged particle optical lens device according to the present invention is useful for a charged particle optical device such as a charged particle microscope or a charged particle beam drawing device.
  • a charged particle optical device such as a charged particle microscope or a charged particle beam drawing device.
  • it is useful because it can be miniaturized and can improve the accuracy of the apparatus and improve the spatial resolution. It is.

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Abstract

A charged particle optical lens device (1) is provided with a charged particle optical lens group which includes a plurality of charged particle optical lenses (24) disposed in stages, and an electric signal distribution device (12) that applies, to each of a plurality of charged particle optical lenses (24), a current or voltage in which the calculation results of electromagnetic field simulation are reflected. The electromagnetic field simulation is simulation for calculating electrostatic potential distribution or magnetic potential distribution produced at the location of each of the plurality of charged particle optical lenses (24) by a charged particle optical lens the lens diameter of which is larger than that of the plurality of charged particle optical lenses.

Description

荷電粒子光学レンズ装置及び荷電粒子光学レンズ装置の制御方法Charged particle optical lens device and method for controlling charged particle optical lens device
　本発明は、荷電粒子光学レンズ装置及び荷電粒子光学レンズ装置の制御方法に関し、特に、荷電粒子顕微鏡及び荷電粒子線露光装置等、静電レンズを用いる荷電粒子線光学装置に使用する荷電粒子光学レンズ装置及び荷電粒子光学レンズ装置の制御方法に関する。 The present invention relates to a charged particle optical lens apparatus and a control method for the charged particle optical lens apparatus, and more particularly to a charged particle optical lens used in a charged particle beam optical apparatus using an electrostatic lens such as a charged particle microscope and a charged particle beam exposure apparatus. The present invention relates to an apparatus and a method for controlling a charged particle optical lens apparatus.
　従来、電子顕微鏡や電子線露光装置、イオン顕微鏡においては荷電粒子線を利用した荷電粒子線照射装置が使用されている。 Conventionally, charged particle beam irradiation apparatuses using charged particle beams have been used in electron microscopes, electron beam exposure apparatuses, and ion microscopes.
　荷電粒子線照射装置では、光学顕微鏡において光を集束するための凸レンズと同様、荷電粒子線を集束するための荷電粒子光学レンズが設けられている。荷電粒子光学レンズには、磁場印加方式の磁場レンズと電界印加方式の静電レンズに分類される。静電レンズは、導電性を有するリング状の電極であり、この電極に所定の電圧を印加することにより、電界分布を発生させ、リング状の電極内を通過する荷電粒子線の軌道を曲げて所定の位置（例えば、観察試料の表面）に集束させる構成をしている。荷電粒子顕微鏡の場合、集束した荷電粒子線により試料表面の形状観察等を行う。荷電粒子線露光装置の場合は、集束した荷電粒子線により試料表面に所定のパターンの描画を行う（例えば、特許文献１参照）。 In the charged particle beam irradiation apparatus, a charged particle optical lens for focusing a charged particle beam is provided in the same manner as a convex lens for focusing light in an optical microscope. The charged particle optical lens is classified into a magnetic field application type magnetic lens and an electric field application type electrostatic lens. An electrostatic lens is a ring-shaped electrode having conductivity. By applying a predetermined voltage to this electrode, an electric field distribution is generated and the trajectory of the charged particle beam passing through the ring-shaped electrode is bent. It is configured to focus on a predetermined position (for example, the surface of the observation sample). In the case of a charged particle microscope, the shape of the sample surface is observed with a focused charged particle beam. In the case of a charged particle beam exposure apparatus, a predetermined pattern is drawn on a sample surface by a focused charged particle beam (see, for example, Patent Document 1).
特開２０１１－２３１２６号公報JP 2011-23126 A
　ここで、従来の荷電粒子線光学装置では、荷電粒子線光学装置の収差により空間分解能が劣化する問題が生じている。収差には複数の種類があるが、例えば球面収差は、レンズの中央部を通る荷電粒子線とレンズの端部を通る荷電粒子線とで、焦点距離が異なることを指す。この収差は、光学顕微鏡でも生じる。光学顕微鏡では、凸レンズと凹レンズとを組み合わせて配置することにより、凸レンズで発生する収差を凹レンズで補正することで、光学顕微鏡全体として、収差を補正している。 Here, in the conventional charged particle beam optical apparatus, there is a problem that the spatial resolution deteriorates due to the aberration of the charged particle beam optical apparatus. Although there are a plurality of types of aberration, for example, spherical aberration indicates that the focal length differs between a charged particle beam passing through the center of the lens and a charged particle beam passing through the end of the lens. This aberration also occurs in an optical microscope. In an optical microscope, by arranging a convex lens and a concave lens in combination, the aberration generated in the convex lens is corrected by the concave lens, thereby correcting the aberration as the entire optical microscope.
　一方、荷電粒子線光学装置では、レンズとして、複数のリング状の電極を多段に配置した静電レンズや磁場レンズが用いられている。荷電粒子顕微鏡に用いるレンズにおいて、回転体のレンズでは、基本的に凸レンズしか作製することができない。そのため、レンズ口径ができるだけ大きな静電レンズを形成し、静電レンズの光軸近傍を通過する荷電粒子線である近軸光線を使用することで、収差の発生を抑制していた。この場合、レンズの小型化が困難であることを意味する。 On the other hand, in the charged particle beam optical apparatus, an electrostatic lens or a magnetic lens in which a plurality of ring electrodes are arranged in multiple stages is used as a lens. In a lens for use in a charged particle microscope, only a convex lens can be basically produced using a rotating lens. For this reason, the generation of aberration is suppressed by forming an electrostatic lens having a lens diameter as large as possible and using a paraxial light beam that is a charged particle beam passing through the vicinity of the optical axis of the electrostatic lens. In this case, it means that it is difficult to reduce the size of the lens.
　また、上記の従来の回転体のレンズによって構成された荷電粒子線光学装置では、一旦発生した収差を補正により低減させることができないため、無収差の荷電粒子線を発生、集束させる光学系が理想的であるといえる。そこで、本発明は、無収差の荷電粒子線を発生することができる荷電粒子光学レンズ装置及び荷電粒子光学レンズ装置の制御方法を提供することを目的とする。 In addition, in the charged particle beam optical apparatus constituted by the above-described conventional rotating body lens, the aberration that has been generated once cannot be reduced by correction. Therefore, an optical system that generates and focuses an aberrated charged particle beam is ideal. It can be said that. Accordingly, an object of the present invention is to provide a charged particle optical lens device capable of generating a non-aberrated charged particle beam and a control method for the charged particle optical lens device.
　上記の課題を解決するため、本発明の一態様に係る荷電粒子光学レンズ装置は、多段に配置された複数の荷電粒子光学レンズを含む荷電粒子光学レンズ群と、前記複数の荷電粒子光学レンズのそれぞれに、電磁界シミュレーションの計算結果を反映させた電圧又は電流を印加する電気信号配分装置とを備え、前記電磁界シミュレーションは、レンズ口径が前記複数の荷電粒子光学レンズよりも大きい荷電粒子光学レンズが前記複数の荷電粒子光学レンズのそれぞれの位置に作り出す静電ポテンシャル分布又は磁気ポテンシャル分布を計算するシミュレーションである。 In order to solve the above problems, a charged particle optical lens device according to an aspect of the present invention includes a charged particle optical lens group including a plurality of charged particle optical lenses arranged in multiple stages, and the plurality of charged particle optical lenses. And an electric signal distribution device that applies a voltage or current reflecting the calculation result of the electromagnetic field simulation, and the electromagnetic field simulation has a lens diameter larger than that of the plurality of charged particle optical lenses. Is a simulation for calculating an electrostatic potential distribution or a magnetic potential distribution created at each position of the plurality of charged particle optical lenses.
　これにより、大型な口径のレンズを使用しなくても、大型な口径のレンズを使用した場合と同一の荷電粒子線を得ることができる。よって、収差を低減するための補正を行うことなく、収差の無い集束性のよい荷電粒子光学レンズ装置を提供することができる。また、装置の大きさを小型化することができる。 This enables to obtain the same charged particle beam as in the case of using a large aperture lens without using a large aperture lens. Therefore, it is possible to provide a charged particle optical lens device with good convergence and no aberration, without performing correction for reducing aberrations. In addition, the size of the device can be reduced.
　また、前記荷電粒子光学レンズ装置は、さらに、前記電磁界シミュレーションを行うための処理装置を備えてもよい。 Moreover, the charged particle optical lens device may further include a processing device for performing the electromagnetic field simulation.
　これにより、荷電粒子光学レンズに最適な電圧を加え、集束性のよい荷電粒子光学レンズ装置を提供することができる。また、荷電粒子光学レンズに高速に電圧を加え、動作速度の速い荷電粒子光学レンズ装置を提供することができる。 Thereby, an optimum voltage can be applied to the charged particle optical lens, and a charged particle optical lens device with good focusing property can be provided. Further, it is possible to provide a charged particle optical lens device having a high operating speed by applying a voltage to the charged particle optical lens at high speed.
　また、前記荷電粒子光学レンズは、環状の形状を有する電極であり、前記電磁界シミュレーションは、静電ポテンシャル分布を計算するシミュレーションであり、前記電気信号配分装置は、前記電極に、前記電磁界シミュレーションの計算結果を反映させた電圧を印加して電界を発生させてもよい。 Further, the charged particle optical lens is an electrode having an annular shape, the electromagnetic field simulation is a simulation for calculating an electrostatic potential distribution, and the electric signal distribution device includes the electromagnetic field simulation on the electrode. An electric field may be generated by applying a voltage reflecting the result of the calculation.
　これにより、シミュレーションにより得られた静電ポテンシャル分布の結果から、荷電粒子光学レンズに印加する電圧を調整することで、集束性のよい荷電粒子光学レンズ装置を提供することができる。 Thus, by adjusting the voltage applied to the charged particle optical lens from the result of the electrostatic potential distribution obtained by the simulation, a charged particle optical lens device with good convergence can be provided.
　また、前記荷電粒子光学レンズは、環状に配置された電磁石であり、前記電磁界シミュレーションは、磁気ポテンシャル分布を計算するシミュレーションであり、前記電気信号配分装置は、前記電磁石に、前記電磁界シミュレーションの計算結果を反映させた電流を印加して磁場を発生させてもよい。 In addition, the charged particle optical lens is an electromagnet arranged in a ring shape, the electromagnetic field simulation is a simulation for calculating a magnetic potential distribution, and the electric signal distribution device is configured to transmit the electromagnetic field simulation to the electromagnet. A magnetic field may be generated by applying a current reflecting the calculation result.
　これにより、シミュレーションにより得られた磁気ポテンシャル分布の結果から、荷電粒子光学レンズに印加する電流を調整することで、集束性のよい荷電粒子光学レンズ装置を提供することができる。 Thus, a charged particle optical lens device with good convergence can be provided by adjusting the current applied to the charged particle optical lens from the result of the magnetic potential distribution obtained by the simulation.
　また、上記の課題を解決するため、本発明の一態様に係る荷電粒子光学レンズの制御方法は、多段に配置された複数の荷電粒子光学レンズに印加する電圧又は電流の値を得るために、前記複数の荷電粒子光学レンズよりもレンズ口径が大きい荷電粒子光学レンズが前記複数の荷電粒子光学レンズのそれぞれの位置に作り出す静電ポテンシャル分布又は磁気ポテンシャル分布を計算する電磁界シミュレーションを行う工程と、前記電気信号配分装置により、前記複数の荷電粒子光学レンズのそれぞれに、前記電磁界シミュレーションの計算結果を反映させた電圧又は電流を印加する工程と、を含む。 In order to solve the above problem, a charged particle optical lens control method according to an aspect of the present invention is to obtain a voltage or current value to be applied to a plurality of charged particle optical lenses arranged in multiple stages. Performing an electromagnetic field simulation for calculating an electrostatic potential distribution or a magnetic potential distribution that a charged particle optical lens having a lens diameter larger than that of the plurality of charged particle optical lenses creates at each position of the plurality of charged particle optical lenses; Applying a voltage or current reflecting the calculation result of the electromagnetic field simulation to each of the plurality of charged particle optical lenses by the electric signal distribution device.
　これにより、大型な口径のレンズを使用しなくても、大型な口径のレンズを使用した場合と同一の荷電粒子線を得ることができる。よって、荷電粒子光学レンズ装置において、収差を低減するための補正を行うことなく、収差の無い集束性のよい荷電粒子線を発生することができる。 This enables to obtain the same charged particle beam as in the case of using a large aperture lens without using a large aperture lens. Therefore, in the charged particle optical lens device, it is possible to generate a charged particle beam with good convergence without any aberration without performing correction for reducing aberration.
　また、前記電磁界シミュレーションの計算結果を反映させた電圧又は電流を印加する工程において、前記複数の荷電粒子光学レンズに印加される前記電圧又は電流は、過去の前記電磁界シミュレーションの計算結果により前記荷電粒子光学レンズに印加された前記電圧又は電流の値のうちから選択されてもよい。 Further, in the step of applying a voltage or current reflecting the calculation result of the electromagnetic field simulation, the voltage or current applied to the plurality of charged particle optical lenses may be determined by the past calculation result of the electromagnetic field simulation. You may select from the value of the said voltage or electric current applied to the charged particle optical lens.
　また、前記電磁界シミュレーションの計算結果を反映させた電圧又は電流を印加する工程において、前記複数の荷電粒子光学レンズに印加される前記電圧又は電流は、前記荷電粒子光学レンズに前記電圧又は電流が印加される前に、その都度前記電磁界シミュレーションにより計算されてもよい。 Further, in the step of applying a voltage or current reflecting the calculation result of the electromagnetic field simulation, the voltage or current applied to the plurality of charged particle optical lenses is the voltage or current applied to the charged particle optical lens. Before being applied, it may be calculated by the electromagnetic field simulation each time.
　これにより、過去に使用した電圧又は電流のデータ又は新たに取得する電圧又は電流のデータにより、荷電粒子光学レンズに最適な電圧を印加して、荷電粒子光学レンズ装置の集束性を向上することができる。また、過去に使用した電圧又は電流のデータを利用することにより、荷電粒子光学レンズに高速に電圧を印加して、荷電粒子光学レンズ装置の動作速度を向上することができる。 Accordingly, it is possible to improve the focusing property of the charged particle optical lens device by applying an optimum voltage to the charged particle optical lens based on voltage or current data used in the past or newly acquired voltage or current data. it can. In addition, by using voltage or current data used in the past, it is possible to apply a voltage to the charged particle optical lens at a high speed to improve the operation speed of the charged particle optical lens device.
　本発明により、無収差の荷電粒子線を発生することができる荷電粒子光学レンズ装置及び荷電粒子光学レンズ装置の制御方法を提供することができる。 According to the present invention, it is possible to provide a charged particle optical lens device capable of generating an aberration-free charged particle beam and a control method for the charged particle optical lens device.
図１は、荷電粒子光学レンズ装置の構成を示す概略図である。FIG. 1 is a schematic diagram showing the configuration of a charged particle optical lens device. 図２は、複数の環状電極を有するレンズ群の一例を示す図である。FIG. 2 is a diagram illustrating an example of a lens group having a plurality of annular electrodes. 図３は、荷電粒子光学レンズ装置の制御手順を説明するためのフローチャートである。FIG. 3 is a flowchart for explaining a control procedure of the charged particle optical lens device. 図４は、電磁界シミュレーションによって得られたポテンシャル分布を示す対象となる領域を示す図である。FIG. 4 is a diagram illustrating a target region indicating a potential distribution obtained by electromagnetic field simulation. 図５Ａは、本実施の形態にかかる荷電粒子光学レンズ装置のより具体的な構成を示す図である。FIG. 5A is a diagram showing a more specific configuration of the charged particle optical lens device according to the present embodiment. 図５Ｂは、電磁界シミュレーションにより得られた各環状電極に印加される電圧を示すデータである。FIG. 5B is data showing the voltage applied to each annular electrode obtained by electromagnetic field simulation. 図６Ａは、アインツェルレンズに電圧を印加したときのポテンシャル分布と荷電粒子線の軌道を示す図である。FIG. 6A is a diagram illustrating a potential distribution and a charged particle beam trajectory when a voltage is applied to the Einzel lens. 図６Ｂは、１４個の環状電極に電圧を印加したときのポテンシャル分布と荷電粒子線の軌道を示す図である。FIG. 6B is a diagram showing a potential distribution and a charged particle beam trajectory when a voltage is applied to 14 annular electrodes. 図６Ｃは、４７個の環状電極に電圧を印加したときのポテンシャル分布と荷電粒子線の軌道を示す図である。FIG. 6C is a diagram showing a potential distribution and charged particle beam trajectories when a voltage is applied to 47 annular electrodes. 図７Ａは、荷電粒子光学レンズ装置の構成を表す図である。FIG. 7A is a diagram illustrating a configuration of a charged particle optical lens device. 図７Ｂは、通常のアインツェルレンズを用いたときのポテンシャル分布を示す図である。FIG. 7B is a diagram showing a potential distribution when a normal Einzel lens is used. 図７Ｃは、荷電粒子光学レンズ装置において発生する荷電粒子線を示す図である。FIG. 7C is a diagram showing charged particle beams generated in the charged particle optical lens device. 図７Ｄは、図７Ｂのアインツェルレンズを用いた場合において発生する荷電粒子線を示す図である。FIG. 7D is a diagram showing charged particle beams generated when the Einzel lens of FIG. 7B is used. 図８Ａは、荷電粒子光学レンズ装置の構成を示す図である。FIG. 8A is a diagram illustrating a configuration of a charged particle optical lens device. 図８Ｂは、仮想的な大型のアインツェルレンズを用いたときの静電ポテンシャル分布を示す図である。FIG. 8B is a diagram illustrating an electrostatic potential distribution when a virtual large Einzel lens is used. 図８Ｃは、荷電粒子光学レンズ装置において発生する荷電粒子線を示す図である。FIG. 8C is a diagram showing charged particle beams generated in the charged particle optical lens device. 図８Ｄは、図８Ｂのアインツェルレンズを用いた場合において発生する荷電粒子線を示す図である。FIG. 8D is a diagram showing charged particle beams generated when the Einzel lens of FIG. 8B is used.
　以下、本発明の実施の形態について、図面を参照しながら説明する。なお、本発明について、以下の実施の形態および添付の図面を用いて説明を行うが、これは例示を目的としており、本発明がこれらに限定されることを意図しない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, although this invention is demonstrated using the following embodiment and attached drawing, this is for the purpose of illustration and this invention is not intended to be limited to these.
　（本発明の基礎となった知見）
　はじめに本発明の基礎となった知見として、近軸光線及び収差について説明する。 (Knowledge that became the basis of the present invention)
First, paraxial rays and aberrations will be described as the knowledge underlying the present invention.
　近軸光線とは、その経路が全て光軸の近傍を通過し、その軌道に関する基礎方程式が線形となる光線を指す。また、収差の中で特に球面収差は、上記に示したように、レンズの中央部を通る光線（荷電粒子線）とレンズの端部を通る光線（荷電粒子線）とで、レンズの中心から光線（荷電粒子線）の集束位置までの距離、焦点距離が異なることを指す。 A paraxial ray refers to a ray whose path passes through the vicinity of the optical axis, and whose basic equation for the trajectory is linear. Among the aberrations, spherical aberration, in particular, is caused by the light beam (charged particle beam) passing through the center of the lens and the light beam (charged particle beam) passing through the end of the lens from the center of the lens. It means that the distance to the focusing position of the light beam (charged particle beam) and the focal length are different.
　近軸光線について、以下に説明する。光軸をｚ軸として、円筒座標系にて静電ポテンシャル
Figure JPOXMLDOC01-appb-M000001
 が満たす基礎方程式は、以下の（式１）のようになる。 The paraxial ray will be described below. Electrostatic potential in cylindrical coordinate system with optical axis as z-axis
Figure JPOXMLDOC01-appb-M000001
 The basic equation satisfied by is as follows (Equation 1).
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　レンズが回転体である場合、ポテンシャルを 
Figure JPOXMLDOC01-appb-M000003
 と置くと、（式１）は以下の（式２）のようになる。 If the lens is a rotating body,
Figure JPOXMLDOC01-appb-M000003
 (Equation 1) becomes the following (Equation 2).
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000004
　回転体の場合、
Figure JPOXMLDOC01-appb-M000005
 はｒの偶関数であり、以下の（式３）ように表現できる。 For rotating bodies,
Figure JPOXMLDOC01-appb-M000005
 Is an even function of r, and can be expressed as (Equation 3) below.
Figure JPOXMLDOC01-appb-M000006
Figure JPOXMLDOC01-appb-M000006
　（式３）を（式２）に代入し
Figure JPOXMLDOC01-appb-M000007
 についての漸化式を求めると、以下の（式４）のようになる。 Substituting (Equation 3) into (Equation 2)
Figure JPOXMLDOC01-appb-M000007
 When the recurrence formula for is obtained, the following (Formula 4) is obtained.
Figure JPOXMLDOC01-appb-M000008
Figure JPOXMLDOC01-appb-M000008
　ただし、
Figure JPOXMLDOC01-appb-M000009
 である。 However,
Figure JPOXMLDOC01-appb-M000009
 It is.
Figure JPOXMLDOC01-appb-M000010
 と置き、
Figure JPOXMLDOC01-appb-M000011
 をｒの２次までで近似すると、以下の（式７）のようになる。
Figure JPOXMLDOC01-appb-M000010
 And put
Figure JPOXMLDOC01-appb-M000011
 Is approximated to the second order of r, the following (Equation 7) is obtained.
Figure JPOXMLDOC01-appb-M000012
Figure JPOXMLDOC01-appb-M000012
　ただし、
Figure JPOXMLDOC01-appb-M000013
 である。軌道の光軸であるｚ軸に垂直な断面においてｘ軸、ｙ軸を定義する。ｘｙｚ座標系において、荷電粒子線の運動方程式は、以下の（式９）のようになる。 However,
Figure JPOXMLDOC01-appb-M000013
 It is. An x-axis and a y-axis are defined in a cross section perpendicular to the z-axis which is the optical axis of the orbit. In the xyz coordinate system, the equation of motion of the charged particle beam is as shown in (Equation 9) below.
Figure JPOXMLDOC01-appb-M000014
Figure JPOXMLDOC01-appb-M000014
　（式７）を（式９）に代入し、ｘ、ｙについて２次以上の項を無視すると、以下の（式１０）（式１１）のようになる。 Substituting (Equation 7) into (Equation 9) and ignoring the second and higher terms for x and y, the following (Equation 10) and (Equation 11) are obtained.
Figure JPOXMLDOC01-appb-M000015
Figure JPOXMLDOC01-appb-M000015
Figure JPOXMLDOC01-appb-M000016
Figure JPOXMLDOC01-appb-M000016
　電位がゼロの荷電粒子放出端から加速され、時刻ｔの荷電粒子の運動エネルギーが軸電位に支配的に決定され、ｘ，ｙ方向の速度はｚ方向に比べて十分小さいとすれば、以下の（式１２）のようになる。 If the charged particle is accelerated from the discharge end of the charged particle whose potential is zero, the kinetic energy of the charged particle at time t is dominantly determined by the axial potential, and the velocity in the x and y directions is sufficiently smaller than that in the z direction, (Formula 12)
Figure JPOXMLDOC01-appb-M000017
Figure JPOXMLDOC01-appb-M000017
　（式１１）の２段目の式は、（式１２）、（式１０）を用いて、ｘ（ｚ）に関する線形微分方程式に変形され、以下の（式１３）のようになる。 (Formula 11) The second-stage formula is transformed into a linear differential equation with respect to x (z) using (Formula 12) and (Formula 10), and becomes the following (Formula 13).
Figure JPOXMLDOC01-appb-M000018
Figure JPOXMLDOC01-appb-M000018
　荷電粒子線の軌道の基礎方程式が線形である場合、収差は発生しない。一点から出た荷電粒子線は必ず一点に集まる。この軌道のことを近軸光線と呼ぶ。すなわち、近軸光線とは、光学系の光軸に対してなす角が小さく、かつ、その経路が全て光軸の近傍を通過する光線を指す。ｒが大きいレンズの端部付近（電極近傍）では、上記の近軸近似は成立しない。したがって、大型レンズを用意して、当該大型レンズにおける光軸近傍の光線を利用する場合は収差は少なくなる。また、レンズが大型であればあるほど、収差は減少することとなる。 Aberration does not occur when the basic equation of the charged particle beam trajectory is linear. Charged particle beams from one point always gather at one point. This orbit is called a paraxial ray. That is, the paraxial light beam refers to a light beam that has a small angle with respect to the optical axis of the optical system and whose path passes through the vicinity of the optical axis. The paraxial approximation described above does not hold near the end of the lens with a large r (near the electrode). Therefore, when a large lens is prepared and light rays near the optical axis of the large lens are used, the aberration is reduced. In addition, the larger the lens, the smaller the aberration.
　しかし、実際には大型レンズを用意することは、荷電粒子光学装置の大きさやコストの点から難しい。そこで、以下、荷電粒子線に理想的な無収差の荷電粒子線を発生することができる、本発明に係る荷電粒子光学レンズ装置及び荷電粒子光学レンズ装置の制御方法について説明する。 However, it is actually difficult to prepare a large lens because of the size and cost of the charged particle optical device. Accordingly, a charged particle optical lens device and a method for controlling the charged particle optical lens device according to the present invention, which can generate an aberrated charged particle beam that is ideal for a charged particle beam, will be described below.
　（実施の形態）
　以下、本実施の形態に係る荷電粒子光学レンズ装置について、図１を用いて説明する。本実施の形態では、荷電粒子顕微鏡に用いられる荷電粒子光学レンズ装置を例として説明する。図１は、本実施の形態に係る荷電粒子光学レンズ装置の構成を示す概略図である。 (Embodiment)
Hereinafter, the charged particle optical lens device according to the present embodiment will be described with reference to FIG. In the present embodiment, a charged particle optical lens device used for a charged particle microscope will be described as an example. FIG. 1 is a schematic diagram illustrating a configuration of a charged particle optical lens device according to the present embodiment.
　図１に示すように、本実施の形態に係る荷電粒子光学レンズ装置１は、真空チャンバ１０内に設けられた複数の環状電極２４で構成される荷電粒子光学レンズ群と、荷電粒子線発生部２１と、電圧印加部１２と、演算部１４とを備えている。なお、環状電極２４は、本発明における荷電粒子光学レンズに相当する。電圧印加部１２は、本発明における電気信号印加装置に相当する。真空チャンバ１０の内部に、荷電粒子線発生部２１に加えて複数の環状電極２４で構成される荷電粒子光学レンズ群を配置することにより、本発明の実施の形態である荷電粒子線光学レンズ装置を用いた荷電粒子線照射装置となる。 As shown in FIG. 1, the charged particle optical lens device 1 according to the present embodiment includes a charged particle optical lens group including a plurality of annular electrodes 24 provided in a vacuum chamber 10, and a charged particle beam generator. 21, a voltage application unit 12, and a calculation unit 14. The annular electrode 24 corresponds to the charged particle optical lens in the present invention. The voltage application unit 12 corresponds to the electric signal application device in the present invention. The charged particle beam optical lens device according to the embodiment of the present invention is arranged in the vacuum chamber 10 by arranging a charged particle optical lens group including a plurality of annular electrodes 24 in addition to the charged particle beam generator 21. The charged particle beam irradiation apparatus using
　本発明における荷電粒子光学レンズである環状電極２４を用いない通常の静電レンズの場合は、例えば、真空チャンバ１０の内部に、荷電粒子線発生部２１に加えて、ウェーネルト電極２５と、加速電極２２と、レンズ電極２６ａ、２６ｂ及び２６ｃとを備えている。加速電極２２は、レンズ電極２６ａと連続している。 In the case of a normal electrostatic lens that does not use the annular electrode 24 that is a charged particle optical lens in the present invention, for example, in addition to the charged particle beam generator 21, a Wehnelt electrode 25 and an acceleration electrode are provided inside the vacuum chamber 10. 22 and lens electrodes 26a, 26b and 26c. The acceleration electrode 22 is continuous with the lens electrode 26a.
　また、真空チャンバ１０内には、計測用のサンプル１６が配置されている。 In the vacuum chamber 10, a measurement sample 16 is disposed.
　荷電粒子線発生部２１は、荷電粒子線を発生するいわゆる荷電粒子源で構成される。荷電粒子線発生部２１で発生した荷電粒子線は、環状電極２４の中を通りサンプル１６に照射される。 The charged particle beam generation unit 21 is configured by a so-called charged particle source that generates a charged particle beam. The charged particle beam generated by the charged particle beam generation unit 21 passes through the annular electrode 24 and is irradiated to the sample 16.
　環状電極２４は、ドーナツ状すなわち円環の形状を有し、例えば、アルミニウム又はＳＵＳ等の非磁性の金属で構成されている。環状電極２４は複数個が積層され、全体として荷電粒子光学レンズ群を構成している。また、積層された各環状電極２４の間には、碍子が設けられ絶縁されている。 The annular electrode 24 has a donut shape, that is, an annular shape, and is made of, for example, a nonmagnetic metal such as aluminum or SUS. A plurality of the annular electrodes 24 are laminated to constitute a charged particle optical lens group as a whole. Further, insulators are provided and insulated between the laminated annular electrodes 24.
　図２は、複数の環状電極２４を有する荷電粒子光学レンズ群の一例を示す図である。図２に示す荷電粒子光学レンズ群は、２０個の環状電極２４を有している。各環状電極２４の間には碍子が設けられ、各環状電極２４は絶縁されている。 FIG. 2 is a diagram showing an example of a charged particle optical lens group having a plurality of annular electrodes 24. The charged particle optical lens group shown in FIG. 2 has 20 annular electrodes 24. An insulator is provided between each annular electrode 24, and each annular electrode 24 is insulated.
　なお、図１に示す荷電粒子光学レンズ装置１では、図１における紙面に向かって左右方向に複数の環状電極２４が配置されている構成を、当該環状電極２４の軸を通るように切断した断面図で示したものである。なお、複数の環状電極２４の間には碍子が設けられているが、図１においては図示を省略している。 In the charged particle optical lens device 1 shown in FIG. 1, a cross section obtained by cutting a configuration in which a plurality of annular electrodes 24 in the left-right direction toward the paper surface in FIG. 1 passes through the axis of the annular electrode 24. It is shown in the figure. An insulator is provided between the plurality of annular electrodes 24, but is not shown in FIG.
　電圧印加部１２は、環状電極２４に印加するための電気信号としての電圧を生成する。電圧印加部１２は、例えばＤ／Ａ（デジタル／アナログ）コンバータで構成されている。なお、電圧印加部１２は、本発明における電気信号配分装置に相当する。 The voltage application unit 12 generates a voltage as an electric signal to be applied to the annular electrode 24. The voltage application unit 12 is configured by, for example, a D / A (digital / analog) converter. The voltage application unit 12 corresponds to the electrical signal distribution device in the present invention.
　演算部１４は、例えばＣＰＵで構成され、環状電極２４に印加するための電気信号（電圧）の値を得るための電磁界シミュレーションを行う。電磁界シミュレーションについては、後に詳述する。なお、演算部１４は、本発明における処理装置に相当する。 The calculation unit 14 is constituted by a CPU, for example, and performs electromagnetic field simulation for obtaining a value of an electric signal (voltage) to be applied to the annular electrode 24. The electromagnetic field simulation will be described in detail later. In addition, the calculating part 14 is corresponded to the processing apparatus in this invention.
　また、図１には、上記した構成とともに、電磁界シミュレーションに用いる、仮想的な環状電極２４の径よりも大きな径の荷電粒子光学レンズ（仮想大型レンズ）を構成するためのウェーネルト電極２５、加速電極２２、レンズ電極２６ａ、２６ｂ及び２６ｃを示している。ウェーネルト電極２５、加速電極２２、レンズ電極２６ａ、２６ｂ及び２６ｃは、ウェーネルト電極、加速電極、アインツェルレンズを想定した仮想電極である。 FIG. 1 also shows a Wehnelt electrode 25 for configuring a charged particle optical lens (virtual large lens) having a diameter larger than the diameter of the virtual annular electrode 24 used for electromagnetic field simulation in addition to the above-described configuration, and acceleration. The electrode 22 and the lens electrodes 26a, 26b and 26c are shown. The Wehnelt electrode 25, the acceleration electrode 22, and the lens electrodes 26a, 26b, and 26c are virtual electrodes assuming a Wehnelt electrode, an acceleration electrode, and an Einzel lens.
　ここで、上記した荷電粒子光学レンズ装置１の制御方法について説明する。図３は、本実施の形態に係る荷電粒子光学レンズ装置１の制御手順を説明するためのフローチャートである。 Here, a control method of the above charged particle optical lens device 1 will be described. FIG. 3 is a flowchart for explaining a control procedure of the charged particle optical lens device 1 according to the present embodiment.
　図３に示すように、はじめに、仮想大型レンズにより発生する、環状電極（小型レンズ）２４の位置における静電ポテンシャル分布を計算する（ステップＳ１２）。すなわち、仮想電極であるウェーネルト電極２５、加速電極２２、レンズ電極２６ａ、２６ｂ及び２６ｃに電圧を印加したと想定した場合に、環状電極２４の位置に発生する電界分布を、電磁界シミュレーションにより計算する。その後、電磁界シミュレーションで計算した静電ポテンシャルと同一の静電ポテンシャルが環状電極２４の位置に発生するように、電圧印加部１２により環状電極２４に電圧を印加する（ステップＳ１４）。これにより、仮想電極であるウェーネルト電極２５、加速電極２２、レンズ電極２６ａ、２６ｂ及び２６ｃに電圧を印加したのと同一の荷電粒子線を実現できる（ステップＳ１６）。なお、電磁界シミュレーションは静電ポテンシャル分布を求めるシミュレーションに限らず、磁気ポテンシャル分布を求めるシミュレーションであってもよい。この場合、荷電粒子光学レンズ群として電磁石を用い、当該電磁石に、電磁界シミュレーションの計算結果を反映させた電流を印加することとしてもよい。また、この場合、電圧印加部１２は、電磁石に印加するための電気信号として電流を出力するとしてもよい。 As shown in FIG. 3, first, the electrostatic potential distribution at the position of the annular electrode (small lens) 24 generated by the virtual large lens is calculated (step S12). That is, when it is assumed that a voltage is applied to the Wehnelt electrode 25, the acceleration electrode 22, and the lens electrodes 26a, 26b, and 26c, which are virtual electrodes, the electric field distribution generated at the position of the annular electrode 24 is calculated by electromagnetic field simulation. . Thereafter, a voltage is applied to the annular electrode 24 by the voltage application unit 12 so that the same electrostatic potential as that calculated by the electromagnetic field simulation is generated at the position of the annular electrode 24 (step S14). As a result, the same charged particle beam as when a voltage is applied to the Wehnelt electrode 25, the acceleration electrode 22, and the lens electrodes 26a, 26b, and 26c, which are virtual electrodes, can be realized (step S16). The electromagnetic field simulation is not limited to the simulation for obtaining the electrostatic potential distribution, but may be a simulation for obtaining the magnetic potential distribution. In this case, an electromagnet may be used as the charged particle optical lens group, and a current reflecting the calculation result of the electromagnetic field simulation may be applied to the electromagnet. In this case, the voltage application unit 12 may output a current as an electric signal to be applied to the electromagnet.
　以下、電磁界シミュレーションについて説明する。図４は、本実施の形態に係る電磁界シミュレーションによる静電ポテンシャル分布を示す対象となる領域を示す図である。以下の電磁界シミュレーションにより得られた結果は、図４に示すように、図１に示した荷電粒子光学レンズ装置１の一部の領域３０における静電ポテンシャル分布を示す。すなわち、当該領域３０は、図１において環状電極２４の中心軸から、径方向の一端までの領域を含む領域である。 The electromagnetic field simulation will be described below. FIG. 4 is a diagram illustrating a region that is a target of the electrostatic potential distribution obtained by the electromagnetic field simulation according to the present embodiment. The results obtained by the following electromagnetic field simulation show the electrostatic potential distribution in a partial region 30 of the charged particle optical lens device 1 shown in FIG. 1, as shown in FIG. That is, the region 30 is a region including a region from the central axis of the annular electrode 24 to one end in the radial direction in FIG.
　はじめに、近軸光線レンズ（荷電粒子光学レンズ装置１）の原理について説明する。なお、本実施の形態に係る荷電粒子光学レンズ装置１では、以下、仮想大型レンズを構成するウェーネルト電極２５、加速電極２２、レンズ電極２６ａ、２６ｂ及び２６ｃのことを簡単にレンズという場合がある。また、環状電極２４についても同様に、簡単にレンズという場合がある。 First, the principle of the paraxial lens (charged particle optical lens device 1) will be described. In the charged particle optical lens device 1 according to the present embodiment, the Wehnelt electrode 25, the acceleration electrode 22, and the lens electrodes 26a, 26b, and 26c constituting the virtual large lens may be simply referred to as a lens hereinafter. Similarly, the annular electrode 24 may be simply referred to as a lens.
　荷電粒子光学レンズ装置１の原理は、上記したとおりである。すなわち、荷電粒子線の軌道方向（照射方向）と同一の方向を軸とする荷電粒子光学レンズ群（複数の環状電極２４）を配置する。その荷電粒子光学レンズ群を構成する環状電極２４のそれぞれに与える電気信号（電圧）を決定するために、仮想的に環状電極２４の径よりも大きな径の荷電粒子光学レンズ（仮想大型レンズ）を構成するウェーネルト電極２５、加速電極２２、レンズ電極２６ａ、２６ｂ及び２６ｃが存在するとして、複数の環状電極２４の位置で生じる静電ポテンシャルを計算する。計算により得られた電気信号（電圧）を実際に複数の環状電極２４に与える。これにより、荷電粒子光学レンズ装置１は、仮想大型レンズを利用した場合に得られる近軸光線と同一の荷電粒子線を発生させるものである。 The principle of the charged particle optical lens device 1 is as described above. That is, a charged particle optical lens group (a plurality of annular electrodes 24) having the same direction as the orbital direction (irradiation direction) of the charged particle beam is arranged. In order to determine an electric signal (voltage) applied to each of the annular electrodes 24 constituting the charged particle optical lens group, a charged particle optical lens (virtual large lens) having a diameter larger than the diameter of the annular electrode 24 is virtually used. Assuming that the Wehnelt electrode 25, the accelerating electrode 22, and the lens electrodes 26a, 26b, and 26c exist, the electrostatic potential generated at the positions of the plurality of annular electrodes 24 is calculated. The electric signal (voltage) obtained by the calculation is actually applied to the plurality of annular electrodes 24. Thereby, the charged particle optical lens device 1 generates the same charged particle beam as the paraxial light beam obtained when a virtual large lens is used.
　以下、本実施の形態にかかる荷電粒子光学レンズ装置の動作についてより具体的に説明する。図５Ａは、本実施の形態にかかる荷電粒子光学レンズ装置のより具体的な構成を示す図である。図５Ｂは、電磁界シミュレーションにより得られた各環状電極２４に印加される電圧を示すデータである。 Hereinafter, the operation of the charged particle optical lens device according to the present embodiment will be described more specifically. FIG. 5A is a diagram showing a more specific configuration of the charged particle optical lens device according to the present embodiment. FIG. 5B is data showing the voltage applied to each annular electrode 24 obtained by electromagnetic field simulation.
　図５Ａに示すように、荷電粒子光学レンズ装置１の基本的な構成は、図１に示した荷電粒子光学レンズ装置１と同様である。図５Ａでは、真空チャンバ１０の外に配置された構成、特に、演算部１４の構成について詳細に示している。 As shown in FIG. 5A, the basic configuration of the charged particle optical lens device 1 is the same as that of the charged particle optical lens device 1 shown in FIG. FIG. 5A shows in detail the configuration arranged outside the vacuum chamber 10, particularly the configuration of the calculation unit 14.
　図５Ａに示すように、真空チャンバ１０内には、図１と同様に、荷電粒子線発生部２１と、ウェーネルト電極２５と、加速電極２２と、複数の環状電極２４とが設けられている。また、サンプル１６は、ＸＹＺステージ１７上に配置されている。サンプル１６が配置された側の、複数の環状電極２４から所定間隔はなれた位置には、２次電子を検出するための２次電子検出器２３が配置されている。なお、レンズ電極２６ａ、２６ｂ及び２６ｃは、仮想的な荷電粒子光学レンズ（仮想大型レンズ）であるため、真空チャンバ１０の外に示している。 As shown in FIG. 5A, in the vacuum chamber 10, as in FIG. 1, a charged particle beam generation unit 21, a Wehnelt electrode 25, an acceleration electrode 22, and a plurality of annular electrodes 24 are provided. The sample 16 is disposed on the XYZ stage 17. A secondary electron detector 23 for detecting secondary electrons is disposed at a position spaced apart from the plurality of annular electrodes 24 on the side where the sample 16 is disposed. Note that the lens electrodes 26a, 26b, and 26c are virtual charged particle optical lenses (virtual large lenses) and are therefore shown outside the vacuum chamber 10.
　また、真空チャンバ１０の外には、電圧印加部１２と、２次電子検出器出力アンプ１８と、ＸＹＺステージプレアンプ１９と、演算部１４とが配置されている。電圧印加部１２の構成は、図１に示したものと同様である。 Further, outside the vacuum chamber 10, a voltage application unit 12, a secondary electron detector output amplifier 18, an XYZ stage preamplifier 19, and a calculation unit 14 are arranged. The configuration of the voltage application unit 12 is the same as that shown in FIG.
　演算部１４は、シミュレーション部３１と、メモリ３２と、マルチチャネルＤＡコンバータ３４と、ＡＤコンバータ３６と、ＤＡコンバータ３８とを有している。 The calculation unit 14 includes a simulation unit 31, a memory 32, a multi-channel DA converter 34, an AD converter 36, and a DA converter 38.
　シミュレーション部３１は、上記した電磁界シミュレーションを行う計算部である。詳細には、環状電極２４の径よりも大きな径の荷電粒子光学レンズ（仮想大型レンズ）が、環状電極２４の位置に生じさせる電界を、有限要素法により計算する。すなわち、ΔΦ（ｒ，ｚ）＝０について、境界条件Ｖｂの下、有限要素法により電界計算を行う。ここで、境界条件Ｖｂとは、仮想大型レンズのレンズ電極２６ａ、２６ｂ及び２６ｃに印加される電圧である。 The simulation unit 31 is a calculation unit that performs the above-described electromagnetic field simulation. Specifically, the electric field generated by the charged particle optical lens (virtual large lens) having a diameter larger than the diameter of the annular electrode 24 is calculated by the finite element method. That is, for ΔΦ (r, z) = 0, the electric field calculation is performed by the finite element method under the boundary condition Vb. Here, the boundary condition Vb is a voltage applied to the lens electrodes 26a, 26b and 26c of the virtual large lens.
　メモリ３２には、シミュレーション部３１において計算された電圧値が、データとして保存されている。図５Ｂに示すように、このデータでは、複数の環状電極２４のそれぞれの位置と電圧値とが対応付けられている。このデータに基づいて、環状電極２４に所定の電圧が印加される。 In the memory 32, the voltage value calculated in the simulation unit 31 is stored as data. As shown in FIG. 5B, in this data, each position and voltage value of the plurality of annular electrodes 24 are associated with each other. Based on this data, a predetermined voltage is applied to the annular electrode 24.
　また、マルチチャネルＤＡコンバータ３４は、メモリ３２に保存されているデータに基づいて、電圧印加部１２に、環状電極２４に印加される電圧の情報を供給する。なお、電圧印加部１２は、電磁界シミュレーションにより環状電極２４に印加される電圧値をその都度計算してもよいし、過去に使用した複数の電磁界シミュレーションのデータをメモリ３２に保存しておいて、その中から選択してもよい。 Further, the multi-channel DA converter 34 supplies information on the voltage applied to the annular electrode 24 to the voltage application unit 12 based on the data stored in the memory 32. The voltage application unit 12 may calculate the voltage value applied to the annular electrode 24 by electromagnetic field simulation each time, or store a plurality of electromagnetic field simulation data used in the past in the memory 32. You may choose from them.
　ＡＤコンバータ３６は、２次電子検出器出力アンプ１８に接続され、２次電子検出器出力アンプ１８から出力された２次電子の情報をデジタルに変換し、電子線が照射される位置情報を得る。また、ＤＡコンバータ３８は、ＸＹＺステージプレアンプ１９に接続され、ＸＹＺステージ１７にアナログ電圧信号を印加することにより、サンプル１６の位置を移動させる。 The AD converter 36 is connected to the secondary electron detector output amplifier 18, converts the secondary electron information output from the secondary electron detector output amplifier 18 into digital information, and obtains position information irradiated with the electron beam. . The DA converter 38 is connected to the XYZ stage preamplifier 19 and moves the position of the sample 16 by applying an analog voltage signal to the XYZ stage 17.
　図６Ａ～図６Ｃは、レンズ群を構成する環状電極２４の数、再現される荷電粒子軌道との関係を示す図である。図６Ａは、アインツェルレンズに電圧を印加したときの静電ポテンシャル分布および荷電粒子線の軌道を示す図である。 6A to 6C are diagrams showing the relationship between the number of the annular electrodes 24 constituting the lens group and the reproduced charged particle trajectory. FIG. 6A is a diagram showing an electrostatic potential distribution and a trajectory of a charged particle beam when a voltage is applied to an Einzel lens.
　図６Ｂは、環状電極２４を１４個設け、１４個の環状電極２４に電圧を印加したときの静電ポテンシャル分布および荷電粒子線の軌道を示す図である。このときの環状電極２４への印加電圧は、図６Ａに示したアインツェルレンズに電圧を印加したときの静電ポテンシャル分布において、環状電極２４の位置に発生した静電ポテンシャルと同一の値を示す。図６Ｃは、環状電極２４を４７個設け、４７個の環状電極２４に電圧を印加したときの静電ポテンシャル分布および荷電粒子線の軌道を示す図である。このときの環状電極２４への印加電圧は、図６Ａに示したアインツェルレンズに電圧を印加したときの静電ポテンシャル分布において、環状電極２４の位置に発生した静電ポテンシャルと同一の値を示す。この際、環状電極２４のリング内側の領域は、図６Ａの場合と同一の静電ポテンシャル分布となる。図６Ａ～図６Ｃにおいて縦軸方向の０ｃｍの位置は、アインツェルレンズ又は環状電極２４の中心位置を示す。また、図６Ａにおけるアインツェルレンズの荷電粒子線と同一の軌道を示す荷電粒子線が、図６Ｃの環状電極２４の中心領域（縦軸方向において、０～０．３ｃｍ程度）の部分に発生している。図６Ａ、図６Ｃにおいて、横軸方向の３０ｃｍの位置は、荷電粒子線の焦点Ｐを示す。図６Ｂでは、荷電粒子線の焦点Ｐは、横軸２８ｃｍの位置である。図６Ｂと図６Ｃとを比較すると、図６Ｂでは環状電極２４の数が十分でないため、図６Ａに示したアインツェルレンズにおける荷電粒子線の焦点Ｐの位置が再現されないのに対し、図６Ｃでは環状電極２４の数を十分増加させたため、荷電粒子線の焦点Ｐは、図６Ａのアインツェルレンズにおける荷電粒子線の焦点Ｐと同一の位置に漸近する。 FIG. 6B is a diagram showing electrostatic potential distributions and charged particle beam trajectories when 14 annular electrodes 24 are provided and a voltage is applied to the 14 annular electrodes 24. The applied voltage to the annular electrode 24 at this time shows the same value as the electrostatic potential generated at the position of the annular electrode 24 in the electrostatic potential distribution when the voltage is applied to the Einzel lens shown in FIG. 6A. . FIG. 6C is a diagram illustrating an electrostatic potential distribution and a charged particle beam trajectory when 47 annular electrodes 24 are provided and a voltage is applied to the 47 annular electrodes 24. The applied voltage to the annular electrode 24 at this time shows the same value as the electrostatic potential generated at the position of the annular electrode 24 in the electrostatic potential distribution when the voltage is applied to the Einzel lens shown in FIG. 6A. . At this time, the region inside the ring of the annular electrode 24 has the same electrostatic potential distribution as in FIG. 6A. 6A to 6C, the position of 0 cm in the vertical axis direction indicates the center position of the Einzel lens or the annular electrode 24. Further, a charged particle beam showing the same trajectory as the charged particle beam of the Einzel lens in FIG. 6A is generated in a central region (about 0 to 0.3 cm in the vertical axis direction) of the annular electrode 24 in FIG. 6C. ing. 6A and 6C, the position of 30 cm in the horizontal axis direction indicates the focal point P of the charged particle beam. In FIG. 6B, the focal point P of the charged particle beam is a position on the horizontal axis 28 cm. Comparing FIG. 6B and FIG. 6C, since the number of the annular electrodes 24 is not sufficient in FIG. 6B, the position of the focal point P of the charged particle beam in the Einzel lens shown in FIG. 6A is not reproduced. Since the number of the annular electrodes 24 is sufficiently increased, the focal point P of the charged particle beam asymptotically approaches the same position as the focal point P of the charged particle beam in the Einzel lens of FIG. 6A.
　次に、図７Ａ～図７Ｄに、仮想大型レンズが存在するとして、環状電極２４に電圧を印加したときの仮想大型レンズの荷電粒子線の発生例を示す。なお、図７Ａ～図７Ｄでは、仮想大型レンズの径に対する環状電極の径が１／２０の場合の電磁界シミュレーションの結果を示している。 Next, FIGS. 7A to 7D show examples of generation of charged particle beams of the virtual large lens when a voltage is applied to the annular electrode 24 assuming that the virtual large lens exists. 7A to 7D show the results of electromagnetic field simulation when the diameter of the annular electrode is 1/20 with respect to the diameter of the virtual large lens.
　ここで、図７Ａは、荷電粒子光学レンズ装置の構成図、図７Ｂは、仮想的な大型のアインツェルレンズを用いたときの静電ポテンシャル分布を示している。図７Ｃは、図７Ａに示した荷電粒子光学レンズ装置１において発生する荷電粒子線を示している。また、図７Ｄは、図７Ｂに示したアインツェルレンズを用いた場合において発生する荷電粒子線を示している。 Here, FIG. 7A is a configuration diagram of the charged particle optical lens device, and FIG. 7B shows an electrostatic potential distribution when a virtual large Einzel lens is used. FIG. 7C shows a charged particle beam generated in the charged particle optical lens device 1 shown in FIG. 7A. FIG. 7D shows a charged particle beam generated when the Einzel lens shown in FIG. 7B is used.
　図７Ｃと図７Ｄとを比較すると、同一の荷電粒子線が発生していることがわかる。したがって、本実施の形態に係る荷電粒子光学レンズ装置１によると、実際に大型な口径のレンズを使用しなくても、大型な口径のレンズを使用した場合と同一の荷電粒子線を得ることができることが分かる。 7C and 7D are compared, it can be seen that the same charged particle beam is generated. Therefore, according to the charged particle optical lens device 1 according to the present embodiment, it is possible to obtain the same charged particle beam as in the case of using a large aperture lens without actually using a large aperture lens. I understand that I can do it.
　よって、本実施の形態に係る荷電粒子光学レンズ装置１を用いた荷電粒子光学装置では、焦点位置の補正を行うのではなく、収差の無い集束性のよい観測又は描画を行うことができる。また、本実施の形態に係る荷電粒子光学レンズ装置１を用いた荷電粒子光学装置では、実際に大型な口径のレンズを使用する必要がないため、装置の大きさを小型化することができる。 Therefore, in the charged particle optical apparatus using the charged particle optical lens apparatus 1 according to the present embodiment, it is possible to perform observation or drawing with good convergence without aberration, without correcting the focal position. In addition, in the charged particle optical device using the charged particle optical lens device 1 according to the present embodiment, it is not necessary to actually use a lens having a large aperture, so that the size of the device can be reduced.
　さらに、図７Ａ～図７Ｄと同様に、図８Ａ～図８Ｄに、仮想的に大きなレンズ口径のレンズが存在するとして、環状電極２４に電圧を印加したときの荷電粒子線の発生例を示す。なお、図８Ａ～図８Ｄでは、仮想大型レンズの径に対する環状電極の径が１／１００の場合の電磁界シミュレーションの結果を示している。 Further, similarly to FIGS. 7A to 7D, FIGS. 8A to 8D show examples of generation of charged particle beams when a voltage is applied to the annular electrode 24 assuming that a lens having a virtually large lens diameter exists. 8A to 8D show the results of electromagnetic field simulation when the diameter of the annular electrode is 1/100 with respect to the diameter of the virtual large lens.
　ここで、図８Ａは、荷電粒子光学レンズ装置の構成図、図８Ｂは、仮想的な大型のアインツェルレンズを用いたときの静電ポテンシャル分布を示している。図８Ｃは、図８Ａに示した荷電粒子光学レンズ装置１において発生する荷電粒子線を示している。また、図８Ｄは、図８Ｂに示したアインツェルレンズを用いた場合において発生する荷電粒子線を示している。 Here, FIG. 8A shows a configuration diagram of the charged particle optical lens device, and FIG. 8B shows an electrostatic potential distribution when a virtual large Einzel lens is used. FIG. 8C shows a charged particle beam generated in the charged particle optical lens device 1 shown in FIG. 8A. FIG. 8D shows a charged particle beam generated when the Einzel lens shown in FIG. 8B is used.
　図８Ｃと図８Ｄとを比較すると、同一の荷電粒子線が発生していることがわかる。したがって、本実施の形態に係る荷電粒子光学レンズ装置によると、大型な口径のレンズを使用しなくても、大型な口径のレンズを使用した場合と同一の荷電粒子線を得ることができることが分かる。 Comparing FIG. 8C and FIG. 8D shows that the same charged particle beam is generated. Therefore, according to the charged particle optical lens device according to the present embodiment, it is understood that the same charged particle beam as that obtained when a large aperture lens is used can be obtained without using a large aperture lens. .
　また、荷電粒子光学レンズ装置１では、焦点位置の補正を行うのではなく、収差の無い荷電粒子光学装置を提供することができる。また、荷電粒子光学レンズ装置１を用いた荷電粒子光学装置では、装置の大きさを小型化することができる。 Also, the charged particle optical lens device 1 can provide a charged particle optical device free from aberrations without correcting the focal position. Further, in the charged particle optical device using the charged particle optical lens device 1, the size of the device can be reduced.
　以上、本実施の形態に係る荷電粒子光学レンズ装置及び荷電粒子光学レンズ装置の制御方法によると、実際に大型な口径のレンズを使用しなくても、大型な口径のレンズを使用した場合と同一の荷電粒子線を得ることができる。よって、荷電粒子光学レンズ装置を用いた荷電粒子光学装置では、収差の補正を行うのではなく、収差の無い荷電粒子線を得ることができ、集束性の高い顕微鏡観察や描画を行うことができる。 As described above, according to the charged particle optical lens device and the control method of the charged particle optical lens device according to the present embodiment, even if the large aperture lens is not actually used, it is the same as the case where the large aperture lens is used. Can be obtained. Therefore, in the charged particle optical device using the charged particle optical lens device, it is possible to obtain a charged particle beam having no aberration, not to correct aberrations, and to perform microscopic observation and drawing with high convergence. .
　また、上記した荷電粒子光学レンズ装置を用いた荷電粒子光学装置では、装置の大きさを小型化することができる。さらに、環状電極の径に対して仮想的な大型の径のレンズの当該径が大きいほど、荷電粒子光学装置の集束性を向上することができる。 Further, in the charged particle optical device using the above charged particle optical lens device, the size of the device can be reduced. Furthermore, the focusing property of the charged particle optical device can be improved as the diameter of the lens having a virtual large diameter with respect to the diameter of the annular electrode is larger.
　なお、上記の演算式、および、演算式の演算手順は、一例であって、別の演算式、および、別の演算手順が用いられてもよい。 Note that the above arithmetic expression and the arithmetic procedure of the arithmetic expression are examples, and another arithmetic expression and another arithmetic procedure may be used.
　また、上記した電磁界シミュレーションの計算結果を反映させた電圧を印加する工程において、複数の環状電極２４に加えられる電圧は、上記したように、過去の電磁界シミュレーションの計算結果により環状電極２４に設定された電圧配分のリストから選択されるものであってもよいし、環状電極２４に電圧が加えられる前に、その都度電磁界シミュレーションにより計算されたものであってもよい。 Further, in the step of applying a voltage reflecting the calculation result of the electromagnetic field simulation described above, the voltage applied to the plurality of annular electrodes 24 is applied to the annular electrode 24 according to the calculation result of the past electromagnetic field simulation as described above. It may be selected from a list of set voltage distributions, or may be calculated by electromagnetic field simulation each time before a voltage is applied to the annular electrode 24.
　また、当該過去の電圧配分のリストを使用する場合には、インターネットなどを利用して共通のデータベースを参照して選択する構成であってもよいし、荷電粒子光学装置ごとにメモリデバイス等を備えて電圧配分のリストを保持する構成であってもよい。 Further, when the past voltage distribution list is used, the list may be selected by referring to a common database using the Internet or the like, and each charged particle optical device includes a memory device or the like. Alternatively, the voltage distribution list may be held.
　このような構成とすれば、過去に使用した電圧配分、又は、新たに取得する電圧配分により、環状電極２４に最適な電圧を印加して、集束性のよい荷電粒子光学レンズ装置を提供することができる。また、過去に使用した電圧配分を利用することにより、環状電極２４に高速に電圧を印加して、動作速度の速い荷電粒子光学レンズ装置を提供することができる。 With such a configuration, it is possible to provide a charged particle optical lens device having a good focusing property by applying an optimum voltage to the annular electrode 24 by voltage distribution used in the past or newly acquired voltage distribution. Can do. Further, by using the voltage distribution used in the past, it is possible to provide a charged particle optical lens device having a high operation speed by applying a voltage to the annular electrode 24 at a high speed.
　また、上記した実施の形態では、荷電粒子光学レンズは、環状の形状を有する電極であり、電磁界シミュレーションは、静電ポテンシャル分布を計算するシミュレーションであり、電圧印加部１２は、環状電極２４に、電磁界シミュレーションの計算結果を反映させた電圧を印加する構成について説明したが、上記した実施の形態に係る荷電粒子光学レンズ装置は、光学レンズが、環状に配置された電磁石であり、電磁界シミュレーションは、磁気ポテンシャル分布を計算するシミュレーションであり、電圧印加部１２は、電磁石に電磁界シミュレーションの計算結果を反映させた電流を印加するとしてもよい。 In the above-described embodiment, the charged particle optical lens is an electrode having an annular shape, the electromagnetic field simulation is a simulation for calculating an electrostatic potential distribution, and the voltage application unit 12 is connected to the annular electrode 24. In the charged particle optical lens device according to the embodiment described above, the optical lens is an annularly arranged electromagnet, and the electromagnetic field is described. The simulation is a simulation for calculating a magnetic potential distribution, and the voltage application unit 12 may apply a current reflecting the calculation result of the electromagnetic field simulation to the electromagnet.
　以上、本発明に係る荷電粒子光学レンズ装置及び荷電粒子光学レンズ装置の制御方法について、上記した実施の形態に基づいて説明したが、本発明は上記した実施の形態に限定されるものではない。実施の形態に対して当業者が思いつく変形を施して得られる形態、および、複数の実施の形態における構成要素を任意に組み合わせて実現される別の形態も本発明に含まれる。 As mentioned above, although the charged particle optical lens apparatus and the control method of the charged particle optical lens apparatus according to the present invention have been described based on the above-described embodiment, the present invention is not limited to the above-described embodiment. Forms obtained by subjecting the embodiments to modifications conceivable by those skilled in the art, and other forms realized by arbitrarily combining components in the plurality of embodiments are also included in the present invention.
　例えば、上記した実施の形態では、荷電粒子光学レンズ装置を荷電粒子顕微鏡に用いる構成について説明したが、荷電粒子光学レンズ装置は、荷電粒子線描画装置等の他の荷電粒子光学装置に用いられてもよい。 For example, in the above-described embodiment, the configuration in which the charged particle optical lens device is used in a charged particle microscope has been described. However, the charged particle optical lens device is used in other charged particle optical devices such as a charged particle beam drawing device. Also good.
　また、上記した荷電粒子光学レンズ装置において、演算部１４等の特定の処理部が実行する処理を、例えば電圧印加部１２や他のコンピュータ等、別の処理部が実行してもよい。また、荷電粒子光学レンズ装置において処理を実行する順番が変更されてもよいし、複数の処理が並行して実行されてもよい。 In the charged particle optical lens device described above, another processing unit such as the voltage application unit 12 or another computer may execute the processing executed by a specific processing unit such as the calculation unit 14. Further, the order of executing the processes in the charged particle optical lens device may be changed, or a plurality of processes may be executed in parallel.
　また、上記した荷電粒子光学レンズ装置の制御方法におけるステップは、コンピュータによって実行されることとしてもよい。また、荷電粒子光学レンズ装置の制御方法に含まれるステップを、コンピュータに実行させるためのプログラムとして実現してもよい。さらに、そのプログラムを記録したＣＤ－ＲＯＭ等の非一時的なコンピュータ読み取り可能な記録媒体として実現してもよい。 Further, the steps in the method for controlling the charged particle optical lens device described above may be executed by a computer. Moreover, you may implement | achieve the step included in the control method of a charged particle optical lens apparatus as a program for making a computer perform. Further, it may be realized as a non-transitory computer-readable recording medium such as a CD-ROM in which the program is recorded.
　本発明に係る荷電粒子光学レンズ装置及び荷電粒子光学レンズ装置の制御方法は、荷電粒子顕微鏡又は荷電粒子線描画装置等の荷電粒子光学装置に有用である。特に、小型であることが要求される卓上用の荷電粒子顕微鏡又は荷電粒子線描画装置等においては、小型化が実現できるとともに、装置の精度を向上して空間分解能を向上することができるため有用である。 The control method of the charged particle optical lens device and the charged particle optical lens device according to the present invention is useful for a charged particle optical device such as a charged particle microscope or a charged particle beam drawing device. In particular, in a desktop charged particle microscope or charged particle beam drawing apparatus that is required to be small, it is useful because it can be miniaturized and can improve the accuracy of the apparatus and improve the spatial resolution. It is.
　　　１　荷電粒子光学レンズ装置
　　１０　真空チャンバ
　　１２　電圧印加部（電気信号配分装置）
　　１４　演算部（処理装置）
　　１６　サンプル
　　２１　荷電粒子線発生部
　　２２　加速電極（仮想電極）
　　２４　環状電極（荷電粒子光学レンズ）
　　２５　ウェーネルト電極（仮想電極）
　　２６ａ、２６ｂ、２６ｃ　レンズ電極（仮想電極）
　　３１　シミュレーション部（処理装置）
　　３２　メモリ
　　３４　マルチチャネルＤＡコンバータ（処理装置） DESCRIPTION OF SYMBOLS 1 Charged particle optical lens apparatus 10 Vacuum chamber 12 Voltage application part (electric signal distribution apparatus)
14 Calculation unit (processing device)
16 Sample 21 Charged particle beam generator 22 Accelerating electrode (virtual electrode)
24 Annular electrode (charged particle optical lens)
25 Wehnelt electrode (virtual electrode)
26a, 26b, 26c Lens electrode (virtual electrode)
31 Simulation unit (processing equipment)
32 Memory 34 Multi-channel DA converter (Processor)

Claims (8)

  1. 　多段に配置された複数の荷電粒子光学レンズを含む荷電粒子光学レンズ群と、
    　前記複数の荷電粒子光学レンズのそれぞれに、電磁界シミュレーションの計算結果を反映させた電圧又は電流を印加する電気信号配分装置とを備え、
    　前記電磁界シミュレーションは、レンズ口径が前記複数の荷電粒子光学レンズよりも大きい荷電粒子光学レンズが前記複数の荷電粒子光学レンズのそれぞれの位置に作り出す静電ポテンシャル分布又は磁気ポテンシャル分布を計算するシミュレーションである
    　荷電粒子光学レンズ装置。     A charged particle optical lens group including a plurality of charged particle optical lenses arranged in multiple stages;
    An electric signal distribution device that applies a voltage or current reflecting the calculation result of the electromagnetic field simulation to each of the plurality of charged particle optical lenses,
    The electromagnetic field simulation is a simulation in which a charged particle optical lens having a lens diameter larger than the plurality of charged particle optical lenses calculates an electrostatic potential distribution or a magnetic potential distribution created at each position of the plurality of charged particle optical lenses. There is a charged particle optical lens device.
  2. 　前記荷電粒子光学レンズ装置は、さらに、
    　前記電磁界シミュレーションを行うための処理装置を備える
    　請求項１に記載の荷電粒子光学レンズ装置。     The charged particle optical lens device further comprises:
    The charged particle optical lens device according to claim 1, further comprising a processing device for performing the electromagnetic field simulation.
  3. 　前記荷電粒子光学レンズは、環状の形状を有する電極であり、
    　前記電磁界シミュレーションは、静電ポテンシャル分布を計算するシミュレーションであり、
    　前記電気信号配分装置は、前記電極に、前記電磁界シミュレーションの計算結果を反映させた電圧を印加する
    　請求項１又は２に記載の荷電粒子光学レンズ装置。     The charged particle optical lens is an electrode having an annular shape,
    The electromagnetic field simulation is a simulation for calculating an electrostatic potential distribution,
    The charged particle optical lens device according to claim 1, wherein the electrical signal distribution device applies a voltage reflecting a calculation result of the electromagnetic field simulation to the electrode.
  4. 　前記荷電粒子光学レンズは、環状に配置された電磁石であり、
    　前記電磁界シミュレーションは、磁気ポテンシャル分布を計算するシミュレーションであり、
    　前記電気信号配分装置は、前記電磁石に、前記電磁界シミュレーションの計算結果を反映させた電流を印加する
    　請求項１又は２に記載の荷電粒子光学レンズ装置。     The charged particle optical lens is an electromagnet arranged in an annular shape,
    The electromagnetic field simulation is a simulation for calculating a magnetic potential distribution,
    The charged particle optical lens device according to claim 1, wherein the electrical signal distribution device applies a current reflecting a calculation result of the electromagnetic field simulation to the electromagnet.
  5. 　電気信号配分装置は、前記電磁界シミュレーションの計算結果を、過去に使用した前記電磁界シミュレーションの計算結果から選択する
    　請求項１～４のいずれか１項に記載の荷電粒子光学レンズ装置。     The charged particle optical lens device according to any one of claims 1 to 4, wherein the electric signal distribution device selects a calculation result of the electromagnetic field simulation from a calculation result of the electromagnetic field simulation used in the past.
  6. 　多段に配置された複数の荷電粒子光学レンズに印加する電圧又は電流の値を得るために、前記複数の荷電粒子光学レンズよりもレンズ口径が大きい荷電粒子光学レンズが前記複数の荷電粒子光学レンズのそれぞれの位置に作り出す静電ポテンシャル分布又は磁気ポテンシャル分布を計算する電磁界シミュレーションを行う工程と、
    　電気信号配分装置により、前記複数の荷電粒子光学レンズのそれぞれに、前記電磁界シミュレーションの計算結果を反映させた電圧又は電流を印加する工程と、を含む
    　荷電粒子光学レンズ装置の制御方法。     In order to obtain a voltage or current value to be applied to a plurality of charged particle optical lenses arranged in multiple stages, a charged particle optical lens having a lens diameter larger than that of the plurality of charged particle optical lenses is provided on the plurality of charged particle optical lenses. A step of performing an electromagnetic field simulation for calculating an electrostatic potential distribution or a magnetic potential distribution created at each position;
    Applying a voltage or current reflecting the calculation result of the electromagnetic field simulation to each of the plurality of charged particle optical lenses by an electric signal distribution device.
  7. 　前記電磁界シミュレーションの計算結果を反映させた電圧又は電流を印加する工程において、
    　前記複数の荷電粒子光学レンズに印加される前記電圧又は電流は、過去の前記電磁界シミュレーションの計算結果により前記荷電粒子光学レンズに印加された前記電圧又は電流の値のうちから選択される
    　請求項６に記載の荷電粒子光学レンズ装置の制御方法。     In the step of applying a voltage or current reflecting the calculation result of the electromagnetic field simulation,
    The voltage or current applied to the plurality of charged particle optical lenses is selected from values of the voltage or current applied to the charged particle optical lens according to past calculation results of the electromagnetic field simulation. 7. A method for controlling a charged particle optical lens device according to 6.
  8. 　前記電磁界シミュレーションの計算結果を反映させた電圧又は電流を印加する工程において、
    　前記複数の荷電粒子光学レンズに印加される前記電圧又は電流は、前記荷電粒子光学レンズに前記電圧又は電流が印加される前に、その都度前記電磁界シミュレーションにより計算される
    　請求項６に記載の荷電粒子光学レンズ装置の制御方法。
          In the step of applying a voltage or current reflecting the calculation result of the electromagnetic field simulation,
    The voltage or current applied to the plurality of charged particle optical lenses is calculated by the electromagnetic field simulation each time before the voltage or current is applied to the charged particle optical lens. Control method of charged particle optical lens device.
PCT/JP2014/002524 2013-05-13 2014-05-13 Charged particle optical lens device and charged particle optical lens device control method WO2014185060A1 (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5379369A (en) * 1976-12-24 1978-07-13 Fujitsu Ltd Electron lens
US4963748A (en) * 1988-06-06 1990-10-16 Arizona Technology Development Corporation (Atdc) Composite multipurpose multipole electrostatic optical structure and a synthesis method for minimizing aberrations
JP2005530314A (en) * 2002-06-15 2005-10-06 エヌエフエイビー・リミテッド Particle beam generator
WO2009119504A1 (en) * 2008-03-26 2009-10-01 株式会社堀場製作所 Electrostatic lens for charged particle radiation
JP2011023126A (en) * 2009-07-13 2011-02-03 Kobe Univ Charged particle beam irradiating device, lithography apparatus, analyzer microscope, charged particle beam emitter, and lens unit for charged particle beam
JP2012227160A (en) * 2006-11-21 2012-11-15 Hitachi High-Technologies Corp Charged particle beam orbit correcting unit and charged particle beam apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5379369A (en) * 1976-12-24 1978-07-13 Fujitsu Ltd Electron lens
US4963748A (en) * 1988-06-06 1990-10-16 Arizona Technology Development Corporation (Atdc) Composite multipurpose multipole electrostatic optical structure and a synthesis method for minimizing aberrations
JP2005530314A (en) * 2002-06-15 2005-10-06 エヌエフエイビー・リミテッド Particle beam generator
JP2012227160A (en) * 2006-11-21 2012-11-15 Hitachi High-Technologies Corp Charged particle beam orbit correcting unit and charged particle beam apparatus
WO2009119504A1 (en) * 2008-03-26 2009-10-01 株式会社堀場製作所 Electrostatic lens for charged particle radiation
JP2011023126A (en) * 2009-07-13 2011-02-03 Kobe Univ Charged particle beam irradiating device, lithography apparatus, analyzer microscope, charged particle beam emitter, and lens unit for charged particle beam

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