WO2018042505A1

WO2018042505A1 - Electromagnetic deflector, and charged particle ray device

Info

Publication number: WO2018042505A1
Application number: PCT/JP2016/075256
Authority: WO
Inventors: 克典梅原; 卓治宮本; 恵介山中; モンローエリック; 明池上; 孝雄林田
Original assignee: 株式会社日立ハイテクノロジーズ
Priority date: 2016-08-30
Filing date: 2016-08-30
Publication date: 2018-03-08

Abstract

The purpose of the present invention is to provide an electromagnetic deflector that reduces third order and fifth order aberration at a high level, and a charged particle ray device. In order to achieve the aforesaid purpose, there are proposed an electromagnetic deflector and a charged particle ray device, said electromagnetic deflector being an electromagnetic deflector that deflects charged particle beams, and has 4n coils for generating a magnetic field that deflects beams of charged particles. The 4n coils are formed so that, within a plane that is perpendicular to the ideal optical axis of the charged particle beam, when a first virtual straight line contacting one end of the coil and a second virtual straight line contacting the other end of the coil intersect so as to have the ideal optical axis of the charged particle beam as the intersection point, an opening angle representing the half angle of the relative angle of the coil side of the two virtual straight lines satisfies at least one of the conditions among θ_A = 36° + a, θ_B = 84° – a, θ_C = a, θ_D = 120° – a (angle condition 1), and θ_A = 72° – b, θ_B = 12° – b, θ_C = b, θ_D = 60° + b (angle condition 2).

Description

Electromagnetic deflector and charged particle beam device

The present disclosure relates to an electromagnetic deflector and a charged particle beam apparatus including the electromagnetic deflector, and more particularly to an electromagnetic deflector in which a coil is wound under a condition that reduces deflection aberration, and the charged particle beam apparatus.

An electromagnetic deflector is an element for changing the direction of movement of electrons by Lorentz force by generating a magnetic field with an electromagnet or the like. The electromagnetic deflector is applied to various apparatuses such as an electron microscope, an electron beam drawing apparatus, and a focused ion beam apparatus.

As an example, in a scanning electron microscope, an electron beam is scanned two-dimensionally on a sample for image formation. An electromagnetic deflector is used for this electron beam scanning.

However, the deflection of the electron beam is accompanied by aberrations. When the aberration is large, the electron beam deviates from the ideal trajectory and the shape thereof is distorted. As a result, in the case of an electron microscope, various adverse effects such as a decrease in resolution, a deterioration in signal-to-noise ratio, and image distortion are caused. Therefore, the electromagnetic deflector is required to reduce deflection aberration.

Non-Patent Document 1 describes that in an electromagnetic deflector, when the coil winding distribution is proportional to cosφ, the deflection magnetic field becomes uniform in the cross section, and third-order and fifth-order aberrations can be reduced.

As disclosed in Non-Patent Document 1, when the winding angle distribution is a cosine distribution, the third-order aberration and the fifth-order aberration can be reduced. It has been clarified that aberrations remain if only cosine distribution is used. In the following, an electromagnetic deflector and a charged particle beam apparatus aiming at reducing third-order and fifth-order aberrations at a higher level are proposed.

As an aspect for achieving the above object, an electromagnetic deflector for deflecting a charged particle beam has 4n coils for generating a magnetic field for deflecting the charged particle beam, and the 4n coils include: In a plane perpendicular to the ideal optical axis of the charged particle beam, a first virtual line that contacts one end of the coil and a second virtual line that contacts the other end of the coil are the ideal optical axis of the charged particle beam. The opening angles indicating the half angle of the relative angle on the coil side of the two imaginary straight lines when intersecting so as to be the intersection are θ _A = 36 ° + a, θ _B = 84 ° −a, θ _C = a, θ _D = 120 ° -a (angle condition 1) and at least one condition of θ _A = 72 ° -b, θ _B = 12 ° -b, θ _C = b, θ _D = 60 ° + b (angle condition 2) The present invention proposes an electromagnetic deflector and a charged particle beam device formed so as to satisfy the above requirements. a, b are real numbers, n is a natural number, θ _A is the opening angle of the first coil, θ _B is the opening angle of the second coil, θ _C is the opening angle of the third coil, and θ _D is the fourth coil. Is the opening angle.

According to the above configuration, third-order and fifth-order aberrations can be reduced at a high level.

The figure which shows an example of the bobbin which comprises a saddle-shaped electromagnetic deflector, and the conducting wire wound around the bobbin. Sectional drawing of a saddle-shaped electromagnetic deflector (the 1). Sectional drawing of a saddle-shaped electromagnetic deflector (the 2). The external view of a saddle type electromagnetic deflector. The block diagram of a scanning electron microscope. The figure explaining arrangement | positioning of the some coil wound by the electromagnetic deflector.

Below, saddle-shaped electromagnetic deflection that can cancel out third-order deflection aberration and fifth-order deflection aberration simultaneously and to the limit by providing an even number of coils with an angle of 2θ when the coil is wound around the bobbin of the electromagnetic deflector The vessel will be described. More specifically, the following embodiments are an electromagnetic deflector and a charged particle beam apparatus, which are mainly used for the electromagnetic deflector, and the opening angle of a coil (in a plane perpendicular to the ideal optical axis of the beam). Thus, 4n (n is 1) where the angle defined by two virtual straight lines crossing the ideal optical axis and passing through two winding positions in a direction parallel to the ideal optical axis of the coil satisfies the predetermined condition. The present invention relates to an electromagnetic deflector having a natural number of coils and a charged particle beam apparatus. According to such a configuration, it is possible to reduce third-order and fifth-order deflection aberrations.

Hereinafter, an electromagnetic deflector capable of canceling the third-order deflection aberration and the fifth-order deflection aberration together will be described with reference to the drawings. FIG. 1 is a schematic diagram of an electromagnetic deflector according to the present embodiment. This electromagnetic deflector allows the bobbin 1 to pass current through the X conductor 2 wound around the bobbin 1 and a Y conductor (not shown) (equivalent to rotating the X conductor 90 ° and wound around the outside of the X conductor). A deflection magnetic field is generated in the central portion of the light beam in a direction orthogonal to the beam optical axis.

The X conductor 2 is provided to deflect the electron beam to the X axis. On the other hand, the Y conducting wire is provided to deflect the electron beam to the Y axis. Hereinafter, in this embodiment, the X conductor 2 will be described, but the same applies to the Y conductor.

On the outer periphery of the bobbin 1, guide grooves 3 are provided in the axial direction of the bobbin 1 (direction parallel to the ideal optical axis of the beam to be deflected). A coil made of the X conductive wire 2 is formed on the bobbin 1 by winding the X conductive wire 2 around the protrusion that forms the guide groove 3. In this embodiment, the pitch of the guide grooves 3 (inner angles of two imaginary straight lines in a plane perpendicular to the ideal optical axis of the beam with the ideal optical axis of the beam as an apex) is described as 6 degrees. Not only the degree but also any angle may be used.

The X conductor 2 is wound from the coil start point 4 in the axial direction of the bobbin 1 (that is, along the longitudinal direction of the guide groove 3). The X conducting wire 2 that has reached the lower end of the bobbin 1 (projection forming the guide groove 3) is once removed from the guide groove 3, and the lower end of the bobbin 1 is wired along the circumference of the bobbin.

Thereafter, the X conductor 2 is wound around a predetermined guide groove and wired to the upper end of the bobbin 1. The X conducting wire 2 reaching the upper end of the bobbin 1 is wired so that the upper end of the bobbin 1 is along the circumference of the bobbin until the coil starting point 4 is reached.

As described above, the X conductor 2 is coiled by winding the X conductor 2 around the bobbin 1. *

The X conductive wire 2 that has reached the coil start point 4 is further routed to another coil start point 5 along the upper end of the bobbin 1 as it is. Then, another coil is formed again along the guide groove 3.

As described above, the deflection magnetic field can be controlled by forming a plurality of coils by the X conductor 2 and passing a current through the X conductor 2.

Here, the central angle of the arc of each coil constituting the electromagnetic deflector _{_{2θ i (0 ° <θ i}} <90 °), when the number of turns of the individual coils and N _i, tertiary aberration, the number 1 Can be represented.
[Equation 1]

On the other hand, the fifth-order aberration can be expressed by Equation 2.
[Equation 2]

Here, m is the number of coils with different central angles, and the total number of turns is as shown in Equation 3.
[Equation 3]

In the electromagnetic deflector, when the angle distribution of the winding is a cosine distribution, the third-order and fifth-order aberrations remain, but in this embodiment, the four coils are considered as one set and the total of the four coils is considered. By wiring so that the aberration is zero, the third-order and fifth-order aberrations are reduced to the limit.

FIG. 2 is a cross-sectional view of the electromagnetic deflector as viewed from above (in the case of an electron microscope, the electron source side). In the electromagnetic deflector of the present embodiment, the X conducting wire 2 is wound so as to be point-symmetric with respect to the central axis of the bobbin 1. Therefore, FIG. 3 shows the upper right portion (0 ° ≦ θ ≦ 90 °) of FIG.

In the bobbin 1 in FIG. 2, a first coil 6, a second coil 7, a third coil 8, and a fourth coil 9 are formed. In FIG. 3, half of the center angle of the arc of the first coil (hereinafter referred to as half angle) is θ _A , half angle 11 of the second coil arc is θ _B , and half angle 12 of the arc of the third coil. Is θ _C , and the half angle 13 of the arc of the fourth coil is θ _D.

Assuming that the number of turns N _i of these coils is constant, in order to reduce the third-order and fifth-order aberrations, the conditions of Equations 4 and 5 (provided that (0 ° <θ _i <90 °)) are satisfied. good.
[Equation 4]

[Equation 5]

First, the third-order aberration will be examined. When the above expression is developed for the first to fourth coils, sin 3θ _A + sin 3θ _B + sin 3θ _C + sin 3θ _D = 0.

Here, in order to make the aberration zero in the first coil and the second coil, and in the third coil and the fourth coil, sin 3θ _A + sin 3θ _B = 0 is modified and sin 3θ _A + sin 3θ _{B is changed.} = 2sin3 / 2 (θ _A + θ _B ) · cos 3/2 (θ _A −θ _B ) = 0 may be satisfied. That is, a combination of θ _A and θ _B satisfying θ _A + θ _B = 120 ° or θ _A −θ _B = 60 ° may be selected. Further, sin3θ _C + sin3θ _D = 0 also expand in the same manner as described _{_{above, θ C + θ D = 120}} °, or θ _C -θ _D = 60 ° satisfies the theta _C, by selecting the combination of theta _D, four coil In all, it is possible to make third-order aberrations zero.

The same applies to the fifth. First, the above equation, when the first deploying the fourth coil, the _{_{_{sin5θ A + sin5θ B + sin5θ C}}} + sin5θ D = 0.

Here, in order to make the aberration zero in the first coil and the second coil, and in the third coil and the fourth coil, sin 5θ _A + sin 5θ _B = 0 is modified and sin 5θ _A + sin 5θ _{B is changed.} = 2sin5 / 2 (θ _A + θ _B ) · cos 5/2 (θ _A −θ _B ) = 0 may be satisfied. That is, a combination of θ _A and θ _B satisfying θ _A + θ _B = 72 ° or θ _A −θ _B = 36 ° may be selected. Further, sin5θ _C + sin5θ _D = 0 also expand in the same manner as described _{_{above, θ C + θ D = 72}} °, or θ _C -θ _D = 36 meet ° theta _C, by selecting the combination of theta _D, four coil In all, the fifth-order aberration can be made zero.

Here, in order to make the third-order and fifth-order aberrations zero simultaneously, it is only necessary to find a combination that can satisfy both the third-order and fifth-order conditions. To find this combination, set up simultaneous equations for θ _A , θ _B , θ _C , and θ _D. This becomes two sets of simultaneous equations from a combination of conditions.

That is,
θ _A + θ _B = 120 °
θ _C + θ _D = 120 °
θ _A −θ _C = 36 °
θ _D + θ _B = 36 ° (i)
Or
θ _A −θ _B = 60 °
θ _D −θ _C = 60 °
θ _A + θ _C = 72 °
θ _D + θ _B = 72 ° (ii)
This simultaneous equation is an indefinite equation.

Therefore, taking parameters a and b (real numbers),
θ _A = 36 ° + a
θ _B = 84 ° -a
θ _C = a
θ _D = 120 ° -a (I)
Or
θ _A = 72 ° -b
θ _B = 12 ° −b
θ _C = b
θ _D = 60 ° + b (II)
And can be expressed as

If the groove has a pitch of 6 ° and the offset is 3 °, the angle at which the coil can be arranged is 3 °, 9 ° ·· 3 + 6n (n = 0, 14). Among these angles, combinations satisfying (I) are 33 °, 87 °, 69 °, 51 ° (when a = 33), and 39 °, 81 °, 75 °, 45 ° (a = 39). In the case of Further, combinations satisfying (II) are 3 °, 9 °, 63 °, and 69 ° (when b = 3). Each combination satisfies the condition for zeroing the third-order and fifth-order aberrations.

Therefore, for example, as shown in the coil external view of FIG. 4, the opening angles (half angles) of the above 33 °, 87 °, 69 °, 51 ° and 39 °, 81 °, 75 °, 45 ° are here. Aberration can be reduced to the limit by winding the coils so as to form eight coils.

FIG. 6 shows bobbin 1 and eight coils (the deflector is configured as a pair with another coil having the same number of turns arranged in axisymmetric position with one coil, so in the example of FIG. 6 there are 16 coils. Is a top view of the deflector including In FIG. 6, in order to explain the positional relationship between the bobbin and each coil in an easy-to-understand manner, the distance between the coils is exaggerated. In FIG. ) Is visible. As illustrated in FIG. 6, the coils 601 to 608 are wound under the opening angle condition of at least one of the above conditions (I) and (II). More specifically, it has 4n coils (n is 2 in the case of FIG. 6), and the 4n coils are arranged at one end of the coil in a plane perpendicular to the ideal optical axis of the charged particle beam. A first virtual straight line (for example, a virtual straight line 610) in contact with a second virtual straight line (for example, a virtual straight line 611) in contact with the other end of the coil has an ideal optical axis 609 of the charged particle beam as an intersection. The opening angle indicating the half angle of the relative angle on the coil side of the two virtual lines when intersecting is configured to satisfy at least one of the above conditions (I) and (II). With such a configuration, it is possible to suppress both third-order aberrations and fifth-order aberrations to a high degree.

Since the deflector is formed by including one or more pairs of coils, the above parameters are selected so that θ _A to θ _D are less than 90 ° (that is, the opening angle of the entire coil is less than 180 °). Is done. In the example of FIG. 6, an example in which eight coils are provided on one side has been described. However, if there are 4n coils (n is a natural number of 1 or more) on one side, the above-described aberration correction effect can be obtained. Therefore, an appropriate number of coils may be selected according to conditions such as deflection intensity.

FIG. 5 is a diagram showing an outline of a scanning electron microscope. The electron beam 104 generated by the voltage of the extraction electrode 102 from the chip 101 of the electron gun 100 is set to a predetermined acceleration voltage by the acceleration electrode 103. The extraction voltage and the acceleration voltage are controlled by the electron gun control device 120. The electron beam 104 is converged by a converging lens 105, shaped by a diaphragm 106, and focused on a sample 114 by an objective lens 113. The convergent lens 105 is controlled by the convergent lens controller 121, and the objective lens 113 is controlled by the objective lens controller 132. By irradiation with the electron beam 104, secondary electrons and backscattered electrons are emitted from the sample 114 and detected by the detector 115. The signal detected by the detector 115 is converted into a digital signal by the A / D converter 131 and becomes a luminance signal corresponding to the amount of emitted electrons.

The electron beam 104 scans the sample 114 two-dimensionally by the upper scanning deflector 110 and the lower scanning deflector 112. The upper scanning deflector 110 and the lower scanning deflector 112 are composed of coils having a central angle distribution such that the third-order fifth-order deflection aberration becomes zero as described above. The beam deflected by the upper scanning deflector 110 is swung back by the lower scanning deflector 112 and scanned so as to have a deflection fulcrum on the lens main surface of the objective lens 113. The magnitude of the deflection depends on the magnetic field intensity generated by the coil. The magnetic field strength can be expressed by the product of the number of turns of the coil and the current. However, in a deflector having zero third-order fifth-order deflection aberration, it is mainly controlled by the current value. Although the magnetic field strength ratio between the upper scanning deflector 110 and the lower scanning deflector 112 depends on the position of the upper scanning deflector 110 and the lower scanning deflector 112, the distance between the upper scanning deflector 110 and the lower scanning deflector 112, the lower scanning deflector 112, and the objective. When the distance to the lens 113 is the same, the magnetic field strength ratio between the upper scanning deflector 110 and the lower scanning deflector 112 is 1: 2.

The number of turns of the lower scanning deflector 112 with respect to the upper scanning deflector 110 needs to be doubled. Accurate adjustment of the magnetic field strength ratio is performed by a current flowing through the upper scanning deflector 110 and the lower scanning deflector 112. Current control of the upper scanning deflector 110 is performed by the upper scanning deflector controller 126, and current control of the lower scanning deflector lower 112 is performed by the lower scanning deflector controller 127. The scanning deflector controller 130 controls the upper scanning deflector controller 126 and the lower scanning deflector controller 127.

Image observation conditions, such as magnification, are input by the input device 135, calculated by the control arithmetic device 133, the deflection amount is calculated, and the scanning deflector controller 130 is controlled. The electron beam 104 is scanned on the sample 114 by the upper scanning deflector 110 and the lower scanning deflector 112 using the main surface of the objective lens 113 as a deflection fulcrum.

Secondary electrons and backscattered electrons obtained based on the scanning of the electron beam 104 are detected by the detector 131, and the control arithmetic device 133 displays an enlarged image on the image display 134 as a luminance signal at a position corresponding to the scanning position. Is displayed.

Further, the scanning electron microscope illustrated in FIG. 5 includes an upper image shift deflector 109 and a lower image shift deflector 111 that electrically move the observation field of view. The image shift deflector has a function of electrically moving the electron beam scanning center on the sample. The electron beam 104 deflected by the upper image shift deflector 109 is turned back by the lower image shift deflector 111 and controlled so as to have a fulcrum on the main surface of the objective lens 113. To act on. The upper image shift deflector 109 and the lower image shift deflector 111 are constituted by a deflector having zero third-order fifth-order deflection aberration as described above. If the distance between the upper image shift deflector 109 and the lower image shift deflector 111 and the distance between the lower image shift deflector 111 and the objective lens 113 are 1: 1, the deflection intensity is 1: 2. The magnetic field strength ratio between the upper image shift deflector 109 and the lower image shift deflector 111 is 1: 2. The number of turns of the lower image shift deflector 111 is twice that of the upper image shift deflector 109. Accurate control is performed by a current flowing through the upper image shift deflector 109 and the lower image shift deflector 111. Current control of the upper image shift deflector 109 is performed by the upper image shift deflector controller 125, and current control of the lower image shift deflector 111 is performed by the lower image shift deflector controller 128. The image shift deflector controller 129 controls the upper image shift deflector controller 125 and the lower image shift deflector controller 128.

In the image observation, the movement amount is input from the input device 135 in order to execute the electric visual field movement. The control arithmetic unit 133 controls the image shift deflector controller 129, and the current required for the deflection is shifted to the upper image shift via the upper image shift deflector controller 125 and the lower image shift deflector controller 128. The field of view moves by being supplied to the deflector 109 and the lower image shift deflector 111. Since the image shift deflector is also a deflector having zero third-order fifth-order deflection aberration, distortion of the electron beam 104 due to image shift does not occur.

These optical elements are arranged so that the tip of the tip of the electron gun 100, the lens optical axis of the converging lens 105, and the lens optical axis of the objective lens 113 are located on the same straight line. In addition, the scanning electron microscope illustrated in FIG. 5 includes an alignment deflector for aligning the electron beam with the ideal optical axis of the beam. In the example of FIG. 5, an upper alignment deflector 107 and a lower alignment deflector 108 are provided. The electron beam 104 that has passed through the electron gun 100 and the converging lens 105 is deflected by the deflection action of the upper alignment deflector 107, further enters the lower alignment deflector 108, and the objective lens 113 is incident on the lower alignment deflector 108. It is deflected so as to be perpendicularly incident on. As described above, the upper alignment deflector 107 and the lower alignment deflector 108 are composed of deflectors having zero third-order fifth-order deflection aberration. The magnetic field intensity required for the deflection is controlled by the upper alignment deflector 107 using the upper alignment deflector controller 122 and the lower alignment deflector 108 using the lower alignment deflector controller 123.

Based on the parallax calculation by wobbling, the control calculation device 133 determines the incident angle and center position of the electron beam, and the alignment deflector controller 124 determines the magnetic field strength required for the upper alignment deflector 107 and the lower alignment deflector 108. The required current is supplied to the upper alignment deflector 107 and the lower alignment deflector 108 via the upper alignment deflector controller 122 and the lower alignment deflector controller 123 to perform the optical axis adjustment. . Since the upper alignment deflector 107 and the lower alignment deflector 108 are composed of deflectors having zero third-order fifth-order deflection aberration, no deflection aberration is caused by this adjustment.

All the built-in deflectors are deflectors that reduce and eliminate third-order and fifth-order aberrations, so that it is possible to provide a scanning electron microscope that suppresses deflection aberrations to zero.

DESCRIPTION OF SYMBOLS 1 Bobbin 2 A pair of coil 3 Guide groove 4 of a conducting wire Coil winding start point 5 Coil winding start point 6 First set coil (center angle)
7 Second set of coils (center angle)
8 Third set of coils (center angle)
9 4th coil (center angle)
10 Half angle of center angle of first set coil 11 Half angle of center angle of second set coil 12 Half angle of center angle of third set coil 13 Half angle of center angle of fourth set coil 100 Electron gun 101 Electron gun Chip 102 Extraction electrode 103 Acceleration electrode 104 Electron beam 105 Converging lens 106 Aperture 107 Upper alignment deflector 108 Lower alignment deflector 109 Upper image shift deflector 110 Upper scan deflector 111 Lower image shift deflector 112 Lower scan deflector 113 Objective lens 114 Sample 115 Detector 120 Electron gun controller 121 Converging lens controller 122 Upper alignment deflector controller 123 Lower alignment deflector controller 124 Alignment deflector controller 125 Upper image shift deflector controller 126 Upper scan Deflector controller 127 Lower scanning deflector system Control unit 128 Lower image shift deflector controller 129 Image shift deflector controller 130 Scanning deflector controller 131 A / D converter 132 Objective lens controller 133 Control arithmetic unit 134 Display unit 135 Input unit

Claims

In an electromagnetic deflector that deflects a charged particle beam,
4n coils each having a conductive wire wound so as to generate a magnetic field in a direction perpendicular to the beam optical axis of the charged particles, and the 4n coils are planes perpendicular to the ideal optical axis of the charged particle beam. Of the first virtual straight line that is in contact with one end of the coil and the second virtual straight line that is in contact with the other end of the coil intersect with each other with the ideal optical axis of the charged particle beam as an intersection. An electromagnetic deflector characterized in that an opening angle indicating a half angle of a relative angle of the virtual side of the coil side satisfies at least one of the following two angle conditions.
Angle condition 1
θ A = 36 ° + a, θ B = 84 ° -a, θ C = a, θ D = 120 ° -a
Angle condition 2
θ A = 72 ° −b, θ B = 12 ° −b, θ C = b, θ D = 60 ° + b
a, b ... real number n ... natural number θ A ... opening angle of first coil θ B ... opening angle of second coil θ C ... opening angle of third coil θ D ... opening angle of fourth coil
In claim 1,
The θ A , θ B , θ C , and θ D are at least one of (33 °, 51 °, 69 °, 87 °) and (39 °, 45 °, 75 °, 81 °), respectively. Electromagnetic deflector.
In claim 1,
Θ A , θ B , θ C , and θ D are (3 °, 9 °, 63 °, and 87 °), respectively.
In claim 1,
Wherein θ A, θ B, θ C , θ D , respectively (33 °, 51 °, 69 °, 87 °) and (39 °, 45 °, 75 °, 81 °) 4n pieces of at least one of An electromagnetic deflector comprising: a coil; and 4n coils each having the above-mentioned θ A , θ B , θ C , and θ D (3 °, 9 °, 63 °, and 87 °).
In a charged particle beam apparatus comprising an electromagnetic deflector for deflecting a charged particle beam emitted from a charged particle source,
The electromagnetic deflector has 4n coils for generating a magnetic field for deflecting the charged particle beam, and the 4n coils have a half angle of a coil opening angle as viewed from the charged particle beam optical axis side as follows. An electromagnetic deflector formed so as to satisfy at least one of the two angle conditions.
Angle condition 1
θ A = 36 ° + a, θ B = 84 ° -a, θ C = a, θ D = 120 ° -a
Angle condition 2
θ A = 72 ° −b, θ B = 12 ° −b, θ C = b, θ D = 60 ° + b
a, b ... real number n ... natural number θ A ... half angle of opening angle of first coil θ B ... half angle of opening angle of second coil θ C ... half angle of opening angle of third coil θ D ... fourth Half angle of coil opening angle
In claim 5,
The electromagnetic deflector includes a scanning deflector that scans the charged particle beam on a sample, a field-of-view deflector that moves a scanning region of the scanning deflector, and an optical axis of the optical element of the charged particle beam device that charges the optical axis. A charged particle beam apparatus comprising at least one alignment deflector for matching particle beams.