WO2015019491A1

WO2015019491A1 - Charged particle beam generating device, charged particle beam device, sample processing method, and sample observation method

Info

Publication number: WO2015019491A1
Application number: PCT/JP2013/071663
Authority: WO
Inventors: 研原田; 照生孝橋
Original assignee: 株式会社日立製作所
Priority date: 2013-08-09
Filing date: 2013-08-09
Publication date: 2015-02-12
Also published as: JPWO2015019491A1; JP6067857B2

Abstract

The purpose of the present invention is to generate a charged particle helix wave while maintaining intensity of a charged particle beam generated by a charged particle source, and easily control the helicity as well as the positivity and negativity (orientation of the winding of the helix) of the charged particle helix wave. The axis of a dipole magnetic field and the optical axis (2) of the charged particle beam device are made parallel, and a charged particle beam source (11) is disposed on the axis of the dipole or on a line extending from the axis such that the magnetic flux lines (81) emanating from one end of the dipole and a charged particle beam (27) interact. Furthermore, the amount of magnetic flux generated by the one end of the dipole and the polarity thereof are controlled such that the trajectories of the charged particle beam (27) discharged by the charged particle beam source (11) and the magnetic flux generated by the one end of the dipole satisfy a condition suitable for generating a helix wave (21).

Description

Charged particle beam generator, charged particle beam device, sample processing method and sample observation method

The present invention relates to a charged particle beam generator, a charged particle beam device, a sample processing method, and a sample observation method.

Research is being conducted to obtain physical property information of a sample using the intensity distribution and phase distribution of the charged particle beam that has passed through the sample after being irradiated with the charged particle beam. In particular, for electron beams, electron beam holography for acquiring physical information such as an electromagnetic field from the phase distribution as an electron wave as well as the intensity of the electron beam has been put into practical use, and applied research is being promoted.

For example, Patent Document 1 discloses a charged particle beam generator in which the tip of an emitter that emits a charged particle beam is disposed below the peak of the magnetic flux density distribution.

JP-A-2-297852

The present inventor is engaged in the research and development of charged particle beam apparatus and is examining the improvement of its performance. In the process, it has been found useful to use a spiral wave as the charged particle beam to be irradiated.

Other issues and novel features will become clear from the description of the present specification and the accompanying drawings.

Of the embodiments disclosed in the present application, the outline of typical ones will be briefly described as follows.

In the charged particle beam device shown in one embodiment disclosed in the present application, the magnetic field axis of the dipole and the optical axis of the charged particle beam device are parallel to each other, and the magnetic flux line and the charged particle beam emitted from one end of the dipole The charged particle source is placed on the axis of the dipole or an extension of the axis (for example, at a predetermined position between the two poles) so that they interact with each other.

Then, the amount of magnetic flux emitted from one end of the dipole and its polarity are controlled so that each trajectory of the charged particle beam emitted from the charged particle source and the magnetic flux emitted from one end of the dipole satisfy the appropriate conditions for generating a spiral wave. To do.

According to the charged particle beam apparatus shown in the following representative embodiment disclosed in the present application, it is possible to generate a charged particle helical wave while maintaining the intensity of the charged particle beam generated from the charged particle source. it can. In addition, the helical degree and positive / negative (direction of spiral winding) of the charged particle helical wave can be easily controlled.

It is a schematic diagram of a spiral wave. It is a schematic diagram which shows a mode that a spiral wave is produced | generated from a helical thin film. It is a schematic diagram which shows a mode that a helical wave is produced | generated from an edge dislocation diffraction grating. 4A, 4B, and 4C are diagrams showing a diffraction grating including a third-order edge dislocation and a small-angle electron diffraction image. It is a schematic diagram explaining the track | orbit and phase (wavefront) of an electron beam. FIGS. 6A and 6B are schematic diagrams showing electron beam paths (orbits) and phases (wavefronts) for explaining the Aharanov-Bohm effect. FIG. 6A shows a single electron source. FIG. 6B is a schematic diagram of two electron beam paths to one observation point, and FIG. 6B is a schematic diagram of two electron beam paths from two electron sources to two observation points. It is. FIG. 7A is a schematic diagram showing a state in which a dotted magnetic flux generator generates an electron spiral wave, and FIG. 7B shows a magnetic flux line and an electron beam from the dotted magnetic flux generator. FIG. FIG. 8A is a schematic diagram showing a relationship between a monopole and an electron spiral wave, and FIG. 8B shows a relationship between a dipole and a stepped electron wave (a pair of electron spiral waves). It is a schematic diagram. FIG. 9A is a schematic diagram showing how an electron spiral wave is generated using one end of a rod-shaped magnetic body, and FIG. 9B is a schematic diagram of an electron spiral wave with distortion. FIG. 10A is a schematic diagram showing the distribution of magnetic flux lines from one end of the solenoid, and FIG. 10B is a schematic diagram showing the distribution of magnetic flux lines from one end of the rod-shaped magnetic body. 10 (C) is a schematic diagram showing the distribution of magnetic flux lines from one end of the superconducting cylinder. FIG. 11A is a schematic diagram showing a relationship between an electron beam emitted from an electron emitting portion of the electron gun Tip and a magnetic flux line, and FIG. 11B shows a magnetic flux line from a dotted magnetic flux generator. It is a projection figure with respect to the plane Q perpendicular | vertical to the optical axis containing the electron emission part of an electron beam. FIG. 12A is a schematic diagram showing the relationship between two electron trajectories emitted from the electron gun Tip and magnetic flux lines, and FIG. 12B is a projection of the electron beam emission region and magnetic flux lines onto the plane Q. FIG. It is a schematic diagram which shows the relationship between two electron orbits emitted from the electron gun Tip and magnetic flux lines. 14A and 14B are projection views showing the deviation between the optical axis and the magnetic field application axis, and FIG. 14A shows the case where the magnetic field application axis is parallel to the optical axis and the position is displaced. FIG. 14B is a diagram illustrating a case where the angle between the magnetic field application axis and the optical axis is deviated. FIGS. 15A and 15B are projection views showing the deviation between the optical axis and the magnetic field application axis, and FIG. 15A is a view showing the case where the magnetic field application axis is in the electron beam emission region. FIG. 15B is a diagram showing a case where the magnetic field application axis is outside the electron beam emission region. It is a schematic diagram which shows an example of the structure which installed the correction coil in the magnetic field application coil. It is a schematic diagram which shows an example of the structure which installed the electron beam deflector in the lower part of the electron gun Tip. It is a schematic diagram which shows an example of the optical system which observes the small angle diffraction image of an electron spiral wave. It is a figure which shows the system structural example of an electron beam apparatus. It is a schematic diagram which shows an example of the electron source part which the electron gun Tip consists of a magnetic body. It is a schematic diagram which shows an example of the electron source part which consists of an electron gun Tip and a magnetic field application coil. It is a schematic diagram which shows an example of the structure which applied the extraction electrode to the electron source part which consists of an electron gun Tip and a magnetic field application coil. It is a schematic diagram which shows an example of the electron source part which consists of an electron gun Tip and a two-stage magnetic field application coil. It is a schematic diagram showing a configuration example in which an extraction electrode is applied to an electron source part composed of an electron gun Tip and a two-stage magnetic field application coil. It is a schematic diagram which shows the other structural example which applied the extraction electrode to the electron source part which consists of an electron gun Tip and a two-stage magnetic field application coil. It is a schematic diagram which shows an example of the electron source part which consists of an electron gun Tip and the magnetic field application coil enclosed by the magnetic path. It is a schematic diagram which shows an example of the electron source part which consists of an electron gun Tip and a magnetic body.

(Embodiment)
Hereinafter, embodiments will be described in detail with reference to the drawings. Before that, a spiral wave and a method of generating a spiral wave will be described. In the following description of the present invention, an electron beam will be mainly described. However, this is because electron beam is the most advanced research, and the present invention is not limited to an electron beam. Is clearly stated.

<1. Spiral wave>
In a coherent optical system, the phase of a propagating light wave is uniquely determined. Surfaces with the same phase are called wavefronts, and wave types such as plane waves and spherical waves are classified based on the shape of the wavefront. On the other hand, there is a case where there is a singular point whose phase is not uniquely determined. For example, a spiral wave having a helical shape centered on an axis having an equiphase surface (generally parallel to the optical axis). This is a phase state in which the phase changes by an integral multiple of 2π when the azimuth is rotated one revolution around the singular point (helical axis) when viewed along a plane perpendicular to the wave propagation direction. It is a wave with FIG. 1 shows a spiral wave 21 classified as a plane wave. As is clear from FIG. 1, the phase on the helical axis 22 is a singular point of the phase, and the phase cannot be determined.

This spiral wave is called a Laguerre Gaussian beam or optical vortex (Hikari Uzu) in optics, and is a light wave that propagates while maintaining its orbital angular momentum, and can apply a force to the isophase plane (wavefront) in the vertical direction. it can. Therefore, it is possible to give momentum to the irradiation target, and it can be used as a manipulation technique such as optical tweezers for manipulating particles that are about the size of a cell, or as laser processing or super-resolution microspectroscopy. it can.

Furthermore, from the fact that multiple orbital angular momentums can be inherent in the portion of the helical axis that is the phase singularity (the strength of the helical winding can be selected as a topological charge (in this embodiment, simply called “helicality”)) It can be used in the field of quantum information communication. In addition, when X-rays are used, it can be applied to physical property analysis, structural analysis, etc., such as analysis of a magnetization state and a three-dimensional image of atomic arrangement.

An electron beam spiral wave (also called an electron spiral wave) propagates while maintaining its orbital angular momentum, so it is expected to create an unprecedented field of application as an electron beam probe (incident beam). The For example, high sensitivity in magnetization measurement, measurement of a three-dimensional state, high-contrast / high-resolution observation of protein molecules and sugar chains, and the like. In particular, in the magnetization observation, the electron beam has the fundamental drawback that it is not sensitive to the magnetization parallel to the propagation direction, but the possibility of observing the magnetization in the electron beam propagation direction is possible with the electron spiral wave. There is. In addition to observation, there is a possibility of application to machining and magnetization control using orbital angular momentum. Therefore, along with the spin-polarized electron beam, the importance of research and development is increasing as a probe for the next-generation electron beam apparatus.

<2. Spiral Wave Generation Method as Related Technology>
There are the following two methods (related techniques 1 and 2) for generating a spiral wave in an electron beam.

FIG. 2 is a schematic diagram showing how a spiral wave is generated from a spiral-shaped thin film. In the first method (related technique 1) for generating a spiral wave, a thin film (helical phase plate 33) having a spiral thickness distribution is irradiated with a plane wave 23, and the phase distribution of the transmitted wave reflects the thickness of the film. It is a method that utilizes the fact that it becomes a spiral shape.

FIG. 3 is a schematic diagram showing a state in which a helical wave is generated from an edge dislocation diffraction grating. A second method (related technique 2) for generating a helical wave is a method using a diffracted wave by a grating including edge dislocations called a fork-type grating.

In the first method (related technique 1), when the wavelength is extremely short like an electron wave, it is difficult to produce a spiral thin film. Therefore, the second method (related technique 2) using a diffraction grating including edge dislocations is more realistic.

As shown in FIG. 3, a spiral wave 21 (a wave having an equal phase plane in a spiral shape) generated as a diffracted wave from a diffraction grating 91 including edge dislocations is a normal point-like diffraction in the diffraction image 9. Instead of the spot 99, a ring-shaped diffraction spot 97 is formed. If one of the ring-shaped diffraction spots can be spatially separated on the diffraction surface, the desired spiral wave 21 can be extracted.

The second method of generating a spiral wave using a diffraction grating including edge dislocations is that the degree of spirality and the sign of the spiral degree are determined by the order of the edge dislocation and the sign of the Burgers vector of the edge dislocation (right and left of the spiral). Winding and left-handing) can be controlled. FIG. 4A is an electron microscope image of the third-order edge dislocation lattice 91 actually created. Using a focused ion beam apparatus, a silicon nitride membrane having a thickness of about 200 nm was processed. Three grids are inserted above the central portion in FIG. 4A, and the grids are concentrated on this part. That is, this concentrated portion is the position of the core of edge dislocation, and the order is third order. The order of the edge dislocations and the order of the generated spirality are basically the same. However, when the diffraction grating has a high contrast and a high-order diffraction spot can be obtained, a spiral wave having a degree of spiral obtained by multiplying the order of the edge dislocation and the order of the diffraction spot is also generated. FIG. 4B is a small angle electron diffraction image 9 obtained when the diffraction grating of FIG. 4A is irradiated with an electron beam with an acceleration voltage of 300 kV. FIG. 4C is a copy of the image of FIG.

This small-angle electron diffraction image 9 is recorded with a camera length of 150 m. ± 1st order, ± 2nd order, ± 3rd order ring-shaped diffraction spots 97 are observed on the left and right of the 0th order spot (dotted diffraction spot 99) in the center, and the ring diameter increases as the diffraction order increases. Thus, it can be seen that spiral waves having a spiral degree of ± 3rd order, ± 6th order, and ± 9th order are generated. That is, the ring diameter of the diffraction spot directly represents the helical degree of the helical wave. As described above, it is possible to generate a plurality of types of helical waves 21 from the diffraction grating 91 including one edge dislocation.

However, in the case of a diffraction grating, the currently used grating is an amplitude grating (a grating that completely shields part of the wave (amplitude)), and the intensity of the diffracted wave is halved when it passes through the grating. is doing. Furthermore, the majority of the intensity of the diffracted wave concentrates on the 0th-order diffracted wave (transmitted wave) that is outside the purpose of use in the present embodiment, and the intensity of the diffracted wave of ± 1st order or higher is further dispersed. The digits are lost. Therefore, the intensity of the diffracted wave of ± 1st order or higher is reduced to a few tenths or less as compared with the incident intensity to the grating (see FIG. 4B). Even if the edge dislocation grating is a phase grating, it is inevitable that the intensity of the diffracted wave of ± 1st order or higher is reduced to a fraction or less as compared with the incident intensity to the grating. The phase grating is a type of grating that changes the phase of a part of the wave, and is a grating that does not change the amplitude, that is, a transparent grating. In observation of a sample using an electron beam with insufficient intensity, a sufficient signal-to-noise ratio cannot be obtained, which hinders resolution and the like. That is, it is important to secure the intensity of the beam for practical use of the electron spiral wave.

<3. Electron orbit and phase difference>
In order to determine the wavefront (phase) of an electron beam at a certain point in the space where the electron beam propagates, path integration (line integration) is performed along one orbit for the phase part of the wave function of the electron wave, and the same value. Connect the points on the trajectory. The surface connecting these points is the wavefront. FIG. 5 is a schematic diagram illustrating the relationship between the electron trajectory 27 and the wavefront 26 (equal phase plane). The trajectory when the electron beam emitted from the electron source 1 reaches the observation point 10 via each trajectory 27 and the state of the wavefront 26 at that time are depicted.

The relationship of FIG. 5 will be described using mathematical expressions. When the coordinate s is taken on the trajectory, the wavefront S ₀ (s) of the electron beam is expressed by the equation (1) from the wave equation that does not depend on time. Here, m is the electron mass, E is the electric field corresponding to the acceleration voltage, e is the electron charge, V is the potential (scalar potential), and _AS is the vector potential.

The phase φ (s) is expressed as shown in Equation (2). Here, h is a Planck's constant.

The phase φ (s) is relative and is not uniquely determined. However, it always makes sense in comparison with other phases, and the phase difference Δφ (s) with other wavefronts is uniquely determined. Therefore, it is possible to propagate the electron beam emitted from one point through the path I and the path II and overlap them to obtain the phase difference Δφ (s) as interference. The phase difference Δφ (s) in this case is shown in Equation (3).

The phase difference Δφ (s) in the equation (3) is the geometric optical path when the change of the orbit is small compared to the wave number on the orbit, that is, when the curvature of the orbit is sufficiently small compared to the wavelength of the electron beam. It can be described in three terms: the contribution of the difference, the contribution of the electric field on the orbit, and the contribution of the magnetic field on the orbit. This approximation is called WKB approximation, and is established with sufficient accuracy for an electron beam with an acceleration voltage of 100 kV or higher. Equation (4) shows the phase difference Δφ (s) separated into the above three terms. However, the wave vector: k = 1 / λ.

The first term Δφ _{1 on} the right side of the equation (4) is a geometric optical path difference (path integral of wave number), and the second term Δφ ₂ is a contribution from the electric field and corresponds to the refractive index in the case of light rays. The third term Δφ ₃ is a magnetic field contribution and does not depend on the acceleration voltage (electron beam wavelength). In the present embodiment, since the electron beam propagating in the vicinity of the optical axis as an electron source is examined, the geometrical optical phase difference of the first term Δφ ₁ and the second term Δφ ₂ are assumed to have no electric field on the orbit. ignore. Therefore, only the contribution from the magnetic field on the orbit of the third term Δφ ₃ is considered.
<4. Aharanov Baume Effect>
According to Stokes' theorem, the third term of the equation (4) is a phase difference Δφ ₃ depending on the magnetic flux density B existing between the two orbits and the area S of the closed surface surrounded by the two orbits (equation ( 5)). This is the Aharanov-Bohm effect (AB effect). Here, S is an area surrounded by the trajectory I and the trajectory II.

That is, as shown in FIG. 6 (A), when the two orbits 27 (paths I and II) of the electron beam are closed, if the magnetic flux passes through a plane (curved surface) defined by the closed path, it is accompanied accordingly. Thus, a phase difference occurs between the two electron beams. In FIG. 6A, an electron beam 27 depicting two orbits emitted from the electron source is drawn so as to return to the observation point 10. This is because the electron beam has a coherent distance limit, so the size of the light source is negligibly small compared to the length of the orbit, and two electron beams are superimposed to observe the phase difference and interfere with each other. Because we must observe, we draw like this. However, as shown in FIG. 6B, even if the start point and the end point of the two electron beams are separated (but sufficiently smaller than the orbital length), the magnetic flux passes through the curved surface defined by the paths of the two electron beams. Then, a phase difference is generated between the two electron beams (FIG. 6B).

As shown in FIG. 7 (A), consider a case where there is a point-like electron source 1 and a magnetic flux generation point B is located downstream thereof. FIG. 7B is a projection view in the direction of the optical axis 2, in which the electron beam 27 is uniformly emitted in the direction of all azimuth angles around the optical axis 2, and at the same time, the generation point of the magnetic flux is the optical axis 2. It is shown that the magnetic flux lines 81 are uniformly flowing (radiating) in the direction of all azimuth angles with the optical axis 2 as the center. At this time, the magnetic flux of the same polarity and the magnetic flux amount B passes through the curved surface of the same area S surrounded by each of the two adjacent electron orbits. That is, each electron orbit obtains the same phase difference (formula (6)). Then, if the sum of the entire phase differences is 2π when it goes around once in the clockwise direction along the moving radius, this electron beam becomes a spiral wave. This embodiment is based on this idea.

<5. Monopole and phase difference>
In FIGS. 7A and 7B, magnetic flux lines are emitted radially from a point magnetic charge having one polarity (N pole or S pole only) or radial to the point magnetic charge. It shows how the magnetic flux is sucked. There is a monopole that draws such a distribution of magnetic flux. Monopole is theoretically predicted to exist and is a magnetic monopole. That is, like a charge, a point magnetic charge having one polarity (only N or S poles) is a point at which magnetic flux lines are emitted radially into a space or magnetic flux is sucked. However, although it is theoretically possible, it has not been found so far. All existing magnetism is a dipole with a pair of poles of N and S poles.

If a monopole exists and is irradiated with a plane wave electron beam, the electron beam after passing through the monopole 83 is spiraled with the projection position of the monopole 83 as the core, as shown in FIG. It has a shape phase distribution 21. FIG. 8B shows an example of a dipole in which two monopoles (83, 84) having opposite polarities are paired. In a dipole, the phase distribution of a spiral shape with a reverse polarity is obtained with the projection position of each pole as a core, and the phase distribution eventually returns to a plane wave at a position away from each core. However, in the case of the monopole shown in FIG. 8A, the phase distribution of the spiral wave 21 remains helical even at a position away from the core. Of course, the degree of change decreases as the distance from the core increases.

In order for a spiral wave to exist stably, the amount of phase change of the electron wave when it circulates around the core must be exactly 2π or an integer multiple of 2π. The condition is derived from equation (6). That is, when the area of the curved surface defined by the two electron beam paths is S, the magnetic flux B × S that passes through S may be an integral multiple (n times) of h / e. When this is expressed again as a mathematical expression, it becomes Expression (7).

The amount of magnetic flux at this time is a magnetic flux amount (2 × h / (2e) = 4.14 × 10 ⁻¹⁵ (Wb)) that is exactly twice the quantized magnetic flux (flux quantum: fluxon) generated in the superconducting state. is there. If there is a monopole with this amount of magnetic flux, the plane wave electron beam passes through the monopole and becomes a spiral wave with a spiral degree of 1.

<6. Use of magnetic field as phase plate for generating spiral wave>
The monopole has not yet been discovered and cannot be used, but it is possible to extend the dipole and use only one end to substitute for the monopole. This is illustrated in FIG. Similar to FIG. 7A, there is a point-like electron source 1, and a rod-like magnetic body 88 is positioned as one end of a dipole on the optical axis on the downstream side in the propagation direction of the electron beam 27. If the amount of magnetic flux emitted from one end of the rod-shaped magnetic body 88 is twice the amount of the magnetic flux quantum (h / (2e)), the spiral around the optical axis 2 is sufficiently downstream from the rod-shaped magnetic body. A spiral wave of degree 1 is generated.

However, as shown in FIG. 9A, the rod-shaped magnetic body has the influence of the other pole, so the distribution of the magnetic flux lines 81 is not uniform in all directions. For this reason, even if the helical winding of the helical wave circulates quantitatively, even if a phase difference of 2π is maintained, the phase change for each unit azimuth is not uniform. Furthermore, in the rod-shaped magnetic body 88, return magnetic flux lines are generated not only from one end of the pole but also from the middle of the rod-shaped magnetic body. Such phase changes and return magnetic flux lines for each unit azimuth cause distortion in the spiral phase distribution. An example of a helical wave including distortion is shown in FIG. The spiral wave 21 in FIG. 9B has a distorted phase plane as compared with FIG.

In FIG. 9A, a rod-shaped magnetic body 88 is assumed as an example of a dipole. However, since the magnetic body 88 creates a shadow with respect to the electron beam 27, the wavefront of the spiral wave is broken (shadowed). ) 24 occurs (lower part of FIG. 9A). In order to generate a magnetic field on the optical axis 2, a magnetic body 88 is necessary. As a result of arranging the magnetic body 88, the electron beam is shielded, creating a tear (shade) 24 in the wavefront of the spiral wave, or unnecessary scattering. generate. For this reason, when the sample is observed using the spiral wave 21, an artifact is generated in the observation image. Such a drawback is a fundamental problem common to the related technique 1 using the helical phase plate.

A method of substituting one end of a magnetic field generated in a one-dimensional form as a monopole uses a solenoid 89 (FIG. 10A), a rod-shaped magnetic body 88 (FIG. 10B), and superconductivity. The case where the cylinder 87 is used (FIG. 10C) can be considered. The effects and problems of the solenoid 89 and the rod-shaped magnetic body 88 are almost the same as those shown in FIG. 9 and are as described above. However, in the control of the amount of magnetic flux, the solenoid 89 is considered easier to handle. . In the case of using the superconducting cylinder 87 (FIG. 10C), when the superconductor is sufficiently cooled and has a sufficient thickness, a magnetic flux quantization effect can be obtained. It can be controlled to a predetermined amount of magnetic flux. Furthermore, since the magnetic flux generation point is limited to the end point of the superconducting cylinder due to the shielding effect of the magnetic field, it is expected that a phase distribution closer to the monopole than in other cases can be obtained. Nevertheless, since it is basically a dipole, the distortion of the phase distribution of the electron wave remains.

As described in detail above, although an electron spiral wave can be generated by the methods shown in

Related Technologies

1 and 2 and the method using one end of the dipole element, it has various problems as summarized below.

(1) Related technology 1: Use of a phase plate having a spiral thickness (see FIG. 2)
In this method, the entire generated electron beam can be formed into a spiral wave, but it is difficult to manufacture a spiral phase plate having sufficient accuracy for an electron beam having a wavelength smaller than the atomic size. In addition, since adjustment after manufacture is almost impossible, it is extremely difficult to adjust the phase difference to an integral multiple of 2π for the spiral core.

(2) Related technology 2: Use of diffraction grating with edge dislocation (see Fig. 3)
As described above, this method has an advantage that it is possible to generate a plurality of types of spiral waves having different degrees of spiral and positive and negative spirals from one edge dislocation lattice. However, this advantage is at the same time a drawback. Since the intensity is dispersed in the generated plurality of spiral waves, it is difficult to obtain a spiral beam having a large intensity. Therefore, when used for sample observation, the S / N ratio of the image deteriorates, and when used for sample (material) processing, the processing efficiency deteriorates. In either case, long exposure is conceivable as a countermeasure, but if the sample drifts during the exposure time, the accuracy of processing and observation deteriorates. If long exposure is assumed, practical use is difficult unless the entire apparatus has sufficient stability.

Furthermore, when this method is used, a diffractive optical system corresponding to a small scattering angle (an optical system with a long camera length) must be used as the electron optical system, and a spiral wave must be selected on the diffraction plane. For this reason, when applied to an electron microscope or the like, it is necessary to additionally install an optical element such as a new optical system and a diaphragm mechanism in addition to a normally used optical system.

(3) Use of one end of dipole element (see Fig. 9)
In this method, a spiral wave can be generated by using one end of a dipole element as a phase plate, as in the related technique 1 (helical phase plate) in (1) above. However, as described above, since the pole at the other end that is not used has an effect, it is difficult to generate a spiral wave having a spiral phase distribution isotropic with respect to the spiral core.

As described above, even if any of the above methods (1) to (3) is used, the generation of the electron spiral wave is considerably difficult at this stage.

Based on the above considerations, the present inventor has come up with a new spiral wave generation method as a result of studies to solve the problems of the above methods (1) to (3). This will be described in detail below.

<Principle of spiral wave generation>
First, the principle of spiral wave generation will be described. FIG. 11 shows a configuration of a tip portion (electron gun Tip11) of an electron gun that is an electron source. Specifically, an electron gun Tip11, an electron beam 27 emitted from the tip of the electron gun Tip11, and a magnetic flux line 81 of a magnetic field applied in a direction parallel to the axis of the electron gun (electron gun Tip11) are shown. Here, since only the electron gun Tip11 is focused on as the electron optical element, it may be considered that the optical axis 2 of the electron beam apparatus coincides with the axis of the electron gun (electron gun Tip11). Furthermore, for the sake of simplicity, the optical axis 2 and the axis in the direction of application of the magnetic field (hereinafter referred to as the magnetic field application axis: a one-dimensional solenoid corresponds to the central axis of the solenoid) coincide with each other. Suppose that Assuming a plane Q perpendicular to the optical axis 2 including a portion (electron emitting portion 12) that mainly emits electrons at the tip of the electron gun Tip11 (see FIG. 11A), an electron beam 27 on the plane Q and Consider the projection of magnetic flux lines 81 (see FIG. 11B). That is, the plane Q is a plane where the electron source exists.

11B is a cross-sectional view of the electron gun Tip11 around the black circle at the center (the plane where the electron source exists, and the hatched portion), and is a projection view, so that the magnetic flux lines 81 spread in all directions from the magnetic field application axis. The electron beam 27 is also a beam that spreads from the optical axis 2 in all directions. However, in FIG. 11B, in order to avoid confusion with the magnetic flux lines 81, the electron beam 27 is drawn so as to be emitted only from the peripheral portion of the electron gun Tip11 (hatched portion). In the projection view of FIG. 11B, the optical axis 2 is drawn at one point, and the magnetic flux lines 81 are also compressed in the optical axis direction. Assuming that the distribution of the magnetic flux lines 81 is axially symmetric about an axis parallel to the optical axis 2, radial magnetic flux lines 81 are drawn with the axis as the center point.

11B shows only the propagation portion of the electron beam 27 in the optical axis direction. Therefore, as is clear from FIG. 11A, the magnetic flux lines 81 above the electron gun Tip11 are not reflected in the projection view, and the magnetic flux lines 81 and the electron beams 27 below the plane Q are mainly projected. Has been drawn. For this reason, in FIG. 11B, the magnetic flux lines 81 are drawn but the return magnetic flux is not affected. This is because, in this projection view, the magnetic flux lines above the electron beam 27 do not pass through the plane (curved surface) defined by the electron beam path and do not contribute to the phase modulation of the electron wave due to the Aharanov-Bohm effect. This is because it is considered to be excluded. As will be described below, this concept is valid, and by creating a relationship between magnetic flux lines and electron beams that can be drawn, it is possible to effectively make the magnetic field monopole.

This will be described in more detail with reference to FIG. FIG. 12 shows the process until the electron beam 27 emitted from the electron gun Tip 11 is detected on the detection recording surface 8 via an electron optical system (not shown). For simplification, electrons are emitted from two different points on the electron gun Tip11 (points A and C: points separated from the optical axis 2 by a distance r, respectively), and route I (AB) and route II (CD), respectively. Pass through. One magnetic flux line 81 passes through the curved surface ABCD defined by the two electron beam paths (I, II). Further, for the sake of simplicity, the magnetic flux lines 81 are applied so as to be perpendicular to the plane Q including the electron beam emission region (cross section of the electron beam emission part 12) and so that the magnetic field application axis coincides with the optical axis 2. Think if you are. Since the magnetic field is applied only in the vicinity of the electron gun having the electron gun Tip11, it can be considered that the orbital length is sufficiently longer between the magnetic field application part and the orbital length of the electron beam 27. Then, it passes through the intersection (Os) of the optical axis 2 and the plane Q including the electron beam emission region, and a sector (Striangular) region (Ss) defined by the arc (one side) defined by the concentric points A and C. All the magnetic flux lines 81 pass through the curved surface ABCD defined by the two electron beam paths I and II only once. There is no return. This relationship is the same regardless of which two electron beam paths having different azimuth angles are selected. Therefore, the magnetic flux line 81 gives the same effect as the monopole for the electron beam 27 emitted from the plane Q including the electron beam emission region. Further, since this effect depends on the Aharanov-Bohm effect (formula (5)), it does not matter which part of the curved surface ABCD defined by the two electron beam paths I and II is transmitted. The magnetic flux lines 81 need only pass through the curved surface ABCD. If the amount of transmitted magnetic flux is appropriate, the electron beam 27 emitted from the electron gun Tip11 passes through the magnetic field application region of the electron gun (electron gun Tip11), and the electrons propagate on the optical axis 2 as they are. It becomes a spiral wave.

<Magnetic field distribution>
If the electron beam emission area has a finite size and one end of the dipole magnetic flux distribution can be transmitted only once through the electron beam emission area, as described above, the electron source acts on the electron beam after emission. The effective magnetic flux becomes a monopole, and as a result, the electron beam can be turned into an electron spiral wave.

Further study will be made using mathematical expressions while referring to FIG. 12 and FIG. FIG. 12A is a schematic diagram showing the relationship between two electron trajectories emitted from the electron gun Tip and magnetic flux lines. FIG. 12B is a projection view onto the plane Q of the electron beam emission region and the magnetic flux lines. FIG. 13 is a schematic diagram showing the relationship between two electron trajectories emitted from the electron gun Tip and magnetic flux lines.

Assuming that the area of the electron source is So and the distance from the electron source to the detection surface is l, √So << l is established in a general electron beam apparatus such as an electron microscope. When only a normal electron optical system exists between the electron source and the detection surface, the electron source image is not distorted, and two distances r from the optical axis and two azimuth angles Δθ are separated. The electron beams 27 emitted from the point A and the point C, which are elementary electron sources, are propagated to the detection recording surface 8 through the electron beam paths I and II while maintaining the azimuth angle Δθ, and are detected at the points B and D. The When the phase difference between the points B and D is ψ, the phase difference is determined based on the equation (8) by the magnetic flux passing through the curved surface (area S ₁₂ ) surrounded by the two trajectories AB and CD. This is the same as equation (7).

For simplification, it is assumed that the emission region of the electron beam projected on the plane Q has a disk shape, and the optical axis and the magnetic field application axis pass through the center of the emission region of the electron beam. In addition, the magnetic flux line 81 passes through the electron beam emission region in parallel with the optical axis 2, but since it is a dipole, it always returns within a finite distance after passing through the electron beam emission region (upward in FIG. 13). ). Therefore, it has an intersection with the orbit of the electron beam. That is, the magnetic flux lines that pass through the electron beam emission region in the optical axis direction eventually become magnetic flux lines that cross the curved surface defined by the irradiation electron trajectory only once. The phase difference between the electron orbits is determined not depending on the crossing position but depending only on the crossing magnetic flux amount. This is the Aharanov-Bohm effect, which is specifically shown in equations (6) to (8). From the above, the phase difference between the electron beam paths I and II is the area Ss on the electron beam emission region defined by the elementary electron sources A and C and the optical axis 2 (hatched portion in FIG. 11B). It is sufficient to consider the amount of magnetic flux that passes through. When the uniform magnetic flux density that passes through the electron beam emission region is set to B ₀ , Equation (8) is rewritten as shown in Equation (9).

As shown in FIG. 13 or FIG. 12B, the trajectory of the electron beam 27 is considered separately for each distance r from the optical axis 2, and the angle at which the line segment connecting the elementary electron sources A and C looks at the optical axis 2 is expressed as Δθ. Then, the phase difference ψ is expressed by Equation (10).

Equation (10) means that as r increases, more magnetic flux lines are transmitted, so that even if they have the same azimuth angle, the phase difference increases as r increases. In order to make the spiral wave a spiral wave that does not depend on the position from the optical axis 2 with the spiral degree n, it is necessary that the phase difference ψ becomes an integral multiple of 2π when Δθ becomes 2π. This condition is shown in equation (11).

From this, it is a condition that Expression (12) is established between the magnetic flux density B (strictly, the component Bz in the optical axis direction) and the distance r from the optical axis 2.

That is, a magnetic flux distribution is formed in which the magnetic flux density decreases in inverse proportion to the square of the distance from the optical axis (also called the off-axis distance) r, and the magnitude of the magnetic flux in the region interacting with the electron beam is quantized. It may be an integral multiple of the magnetic flux (h / e = 4.14 × 10 ⁻¹⁵ (Wb)). The sign of this integer means the direction of the magnetic flux lines, that is, the direction of winding of the spiral of the electron spiral wave. When this integer is a negative value, it means that the direction of the magnetic flux line is opposite to that of a positive value, that is, the winding direction of the spiral of the electron helical wave is reversed from that of a positive value.

<Regarding misalignment between optical axis and magnetic field application axis>
In order to enable the above-described simplification, it is necessary that the optical axis 2 of the electron beam apparatus or the axis of the electron gun (electron gun Tip 11) coincide with the magnetic field application axis. For example, the magnetic field application axis 29 may be misaligned with the optical axis 2 (FIG. 14A), or the magnetic field application axis 29 and the optical axis 2 may not be parallel (FIG. 14B). . In any case, when a projection view of the electron beam 27 and the magnetic flux line 81 onto the plane Q including the electron beam emission region (cross section of the electron beam emission part 12) is considered, it is as shown in FIG. A deviation between the optical axis 2 and the magnetic field application axis 29 can be regarded as a deflection in the deviation direction. Accordingly, it is possible to match the optical axis 2 and the magnetic field application axis 29 by applying a correction magnetic field in the horizontal direction. If not corrected, the amount of phase change per unit azimuth angle when the optical axis is the center is not uniform, and as shown in FIG. 9B, distortion occurs in the phase distribution of the spiral wave. .

In addition, the amount of deviation between the optical axis 2 and the magnetic field application axis 29 is large, and the magnetic field application axis 29 goes out of the electron beam emission region (cross section of the electron beam emission part 12, hatching part) in the projection image. In FIG. 15B, the radial magnetic flux lines 81 cannot be drawn around the optical axis 2 and a spiral wave can no longer be obtained. This is because, in the case of FIG. 15B, although the magnetic field is distributed, the overall magnetic field distribution is similar to the situation in which the deflection magnetic field B is applied from the upper right to the lower right in the figure. It is. Thus, in the present embodiment, the magnetic field application axis 29 must be present inside the electron beam emission region (cross section of the electron beam emission part 12). That is, when a deviation occurs between the optical axis 2 and the magnetic field application axis 29, particularly when the magnetic field application axis 29 is not located inside the electron beam emission region (cross section of the electron beam emission part 12). Need to be corrected. In order to improve the accuracy in machining and match the optical axis 2 and the magnetic field application axis 29, when an accuracy higher than the machining accuracy is required, an axis adjustment using an electromagnetic field may be performed.

When correcting the direction and intensity of the magnetic flux line distribution, or when adjusting the electron beam emission direction and emission site to the magnetic field application axis, an axis adjustment method using an electromagnetic field is required. The axis adjustment method is not limited, but the following two methods can be exemplified. As a first method, there is a method in which a correction magnetic field is applied in the horizontal direction to align the optical axis and the magnetic field application axis (FIG. 16). As a second method, there is a method of aligning the electron beam emission direction and emission site with the magnetic field application axis (FIG. 17).

For correction of the magnetic field application axis, as shown in FIG. 16, two upper and lower mini-coils (magnetic field correction coils) 14 arranged across the optical axis 2 are arranged in the horizontal direction along the outer circumference of the coil 13, respectively. It can be used as a correction unit. By arranging the upper and lower two stages, it is possible to correct both the angle and the position of the magnetic field.

Also, an electric field is used to adjust the electron beam emitting part. For example, as shown in FIG. 17, it can be used as a correction unit in which parallel plate electrodes (correction electrodes) 15 are arranged so as to face each other with the optical axis 2 sandwiched between two upper and lower stages. Although simplified in FIG. 17, a plurality of pairs of parallel plate electrodes 15 are arranged along the outer periphery of the optical axis 2 even in the electric field type.

As the correction unit according to the above method, a technique used in an apparatus using an electron beam can be appropriately employed. However, in the present embodiment, the correction unit is disposed in the vicinity of the electron source and is affected by the acceleration voltage of electrons, and thus needs to be configured to withstand a high voltage.

<Irradiation of electron spiral wave to sample and observation of sample transmission>
In the present embodiment, the electron beam emitted from the electron gun Tip11 becomes an electron spiral wave after passing through the magnetic field application region. Since this is realized in a very narrow range in terms of space, when viewed from the electron optical system on the downstream side of the electron beam flow, the situation is equivalent to the case where the electron spiral wave is directly emitted. Therefore, the same handling as that of an electron beam apparatus such as a conventional electron microscope is sufficient for irradiating the sample with an electron beam and observing a sample image and a diffraction image of the sample. This is also one of the great advantages of this embodiment.

When a sample is coated with a resist or the like, for example, since it is an electron beam storing the orbital angular momentum, it is possible to perform exposure and drawing with different accuracy and contrast from the conventional one. Further, since it is possible to transmit the momentum, it is also possible to transmit a driving force to microcomponents and nanocomponents by irradiating with an electron beam and use them as a power source.

Also, in the observation of the image, since it is an electron beam conserving the orbital angular momentum, observation of the magnetization distribution in the optical axis direction, which has not been obtained conventionally, or a right-handed spiral structure such as protein or sugar chain, or It is expected to obtain contrast corresponding to left-handed.

As described above, it is possible to adopt the same optical system parts as in the past, but a small-angle diffractive optical system is required to confirm whether the generated electron beam is a spiral wave or not. This will be described next.

<Adjustment of spirality by small angle electron diffraction optical system>
The fact that the electron beam obtained by applying a magnetic field is an electron spiral wave is known from the fact that the image of the electron source (formally a spot shape) is ring-shaped by small-angle electron diffraction. be able to. In addition, the degree of spirality can be known from the size of the ring. This means that, for example, the diffraction image observation optical system shown in FIG. 3 is assembled. However, since no diffraction grating is used, only the central portion (the zero-order spot portion in FIG. 4B) is the observation target.

For example, the following method can be considered as a method of adjusting the spiral degree.

<1> When a magnetic field is applied to the electron gun portion in the same direction as the optical axis and the magnetic field intensity is changed, the spot-like spot changes to a ring-shaped spot (RSP1) when a predetermined magnetic flux is obtained.

<2> If the magnetic field intensity is increased as it is, the ring-shaped spot (RSP1) returns to a spot-like spot.

<3> Further, as the magnetic field strength is increased, the spot-like spot becomes a ring-like spot (RSP2) again.

<4> At this time, the diameter of the ring-shaped spot (RSP2) is larger than that of the immediately preceding ring-shaped spot (RSP1). This is because the number of magnetic flux lines passing through the curved surface defined by each electron beam path has doubled, and the helical degree has also doubled.

When observation is continued while applying a magnetic field in this way, the diameter of the ring increases while periodically repeating a spot-like spot and a ring-like spot. In this method of checking the electron spiral wave, the frequency of the spiral wave is known, but the positive / negative cannot be determined. The direction (polarity) of the applied magnetic field must be defined in advance.

FIG. 18 shows a configuration example of the small angle electron diffraction optical system. The optical system shown in FIG. 18 has a configuration in which an image (crossover) of a light source is connected to an object surface of a first intermediate lens by a second condenser lens. Such an optical system is an optical system having a relatively large camera length (for example, 1000 m or more). The camera length is a parameter corresponding to the magnification in the diffraction image, and the smaller the camera length, the smaller the deflection angle can be observed. In order to confirm the electron spiral wave, it is necessary to observe the intensity distribution of the ring-shaped spot corresponding to the first-order diffraction spot. Therefore, as a proven value, a camera length of 80 m or more is desirable (for example, in FIG. 4B, the camera length was 150 m).

Further, it is preferable that the opening angle of the irradiated electron beam is small. The opening angle is an angle at which the image (crossover) of the light source directly above the sample position is viewed. The smaller the opening angle, the higher the parallelism. This is because the spread of the beam of the irradiation electron beam is reflected as the spread of the diffraction spot in the diffraction image, and there is a possibility that the ring-shaped spot of the spiral wave may be erased by overlapping the spread. In view of practicality, an opening angle of 1 × 10 ⁻⁶ rad or less is desirable because a diffraction image with a spiral degree of 1 must be observable.

Note that the configuration of the small-angle electron diffraction optical system is not limited to that shown in FIG. 18, and other configurations may be used. Whichever optical system is used, it is only necessary to have a camera length capable of resolving the ring-shaped spot shape.

FIG. 19 is a diagram showing a configuration example of the entire system of an electron beam apparatus including an electron source device that generates an electron spiral wave. Although it is drawn with a lens configuration assuming a general-purpose electron microscope having an acceleration voltage of about 300 kV, it is not limited to an electron microscope having this configuration.

As shown in FIG. 19 (see also FIG. 18), the electron gun Tip11 is disposed in the vicinity of the coil 13 capable of applying a magnetic field in the direction of the optical axis 2. The electron source 1 (electron gun Tip11) is connected to and controlled by the control system 19 of the electron source. The coil 13 is connected to a control system (a control system of a coil for generating a helical wave) 17, and the amount of magnetic flux generated for generating a helical wave is controlled by the control system 17. In FIG. 19, the sample to be observed and the sample 3 to be processed are shown, but the sample 3 is not necessary when confirming that the electron beam is an electron spiral wave by a small-angle diffraction image.

The electron orbit 27 shown in FIG. 19 is the one at the time of small angle diffraction. That is, with the objective lens 5 turned off, an electron beam crossover is formed on the object surface of the first intermediate lens 61, and the lower imaging lens system (62, 63, 64) detects the crossover. An enlarged projection is made on the recording surface 8. For example, the diffraction image 35 formed on the detection recording surface 8 is observed on the screen of the image data monitor 76 via the detector 79 and the controller 78 and stored as image data in the recording device 77. In FIG. 19, an image of a ring-shaped diffraction spot (diffraction image 35) is displayed on the screen of the image data monitor 76 as an example of a spiral wave. Needless to say, various lens configurations and observation conditions shown in the system of FIG. 19 are merely examples.

As shown in FIG. 19, the electron beam apparatus is systematized as a whole, and the operator can check the control state of the apparatus on the screen of the monitor 52, and the system control computer 51 is set by input using the interface 53. Thus, each component of the small-angle electron diffraction optical system can be controlled. Each component includes, for example, the electron source 1, a coil 13 for generating a spiral wave, an acceleration tube 40, each lens (41, 42, 5, 61, 62, 63, 64), a sample 3 (sample holding device), Detector 79 or the like. Reference numeral 39 denotes a control system for the sample holding device, and 49 denotes a control system for the acceleration tube. Of the lenses (41, 42, 5, 61, 62, 63, 64), 41 is a first condenser lens, and 42 is a second condenser lens. It is controlled by a control system 47 of a two condenser lens. Reference numeral 5 denotes an objective lens, which is controlled by the objective lens control system 59. Reference numeral 61 denotes a first intermediate lens, 62 denotes a second intermediate lens, 63 denotes a first projection lens, and 64 denotes a second projection lens. The first intermediate lens control system 69 and the second intermediate lens, respectively. Control is performed by a lens control system 68, a first projection lens control system 67, and a second projection lens control system 66.

Although the electron beam apparatus has other components such as a beam deflection system and a vacuum exhaust system, illustration and description of the components not directly related to the present embodiment are omitted.

Hereinafter, configuration examples 1 to 5 of the electron source section (electron beam generator) of the present embodiment will be described with reference to the drawings. As used herein, the electron source section refers to an electron source and a magnetic field generator, which may be the same device as in Configuration Example 1, or may be separate devices as in Configuration Examples 2-5. . Moreover, the electron source part illustrated below is used as an electron source part of the electron beam apparatus mentioned above, for example.

<Configuration example 1>
FIG. 20 is a cross-sectional view showing Configuration Example 1 of the electron source section of the present embodiment. In FIG. 20, a magnetic material is used for the electron gun Tip11, and the electron gun Tip11 itself constitutes a part of a dipole. Since the tip of the electron gun Tip11 is one end of the dipole, the magnetic flux line 81 emitted from the tip into the space and the electron beam 27 emitted from the tip of the electron gun Tip11 are the magnetic flux lines 81 described with reference to FIG. The relationship with the electron beam 27 is configured. In other words, a magnetic field (magnetic flux line 81) that immerses the electron beam 27 is generated. Therefore, when the magnetic flux line 81 emitted from the electron gun Tip11 has the above-described appropriate magnetic flux amount, the electron beam 27 becomes the spiral wave 21 as described in the lower part of FIG.

The amount of magnetic flux flowing through the electron gun Tip11 can be controlled by the following method. For example, as a magnetic material used for the electron gun Tip11, a magnetic material whose amount of magnetic flux changes with temperature is used, and a heating unit such as a heater is provided around the electron gun Tip11. In this case, the amount of magnetic flux (magnetic flux distribution) can be controlled by changing the temperature of the electron gun Tip11 with a heater. Further, a magnetic field generator such as a coil connected to the electron gun Tip11 may be provided. In this case, the amount of magnetic flux flowing through the electron gun Tip11 can be controlled by the magnetic field generator.

Also, the polarity of magnetic flux lines can be reversed by the following method. For example, a strong magnetic field higher than the reversal magnetization of the magnetic material is applied from the outside to the magnetic material constituting the electron gun Tip11. In addition, a magnetic field having a reverse polarity is applied in a state where the magnetic body constituting the electron gun Tip11 is heated to a temperature equal to or higher than the Curie temperature of the magnetic body. In this case, the magnetic field may be weak.

This configuration example 1 has the advantage that the generation source of the magnetic flux line and the electron beam are the same, and there is little deviation between the optical axis (the axis of the electron gun Tip 11) and the magnetic field application axis.

<Configuration example 2>
FIG. 21 is a cross-sectional view showing a configuration example 2 of the electron source section of the present embodiment. In FIG. 21, an electron gun Tip 11 is arranged inside a hollow coil (cylindrical coil) 13. In this case, the electron source has an electron gun including an electron gun Tip 11, and the magnetic field generator has a hollow coil 13. A central axis of the cylindrical hollow coil 13 is a magnetic field application axis 29. This magnetic field application axis 29 and the axis of the electron gun Tip11, that is, the optical axis 2 of the electron source device (the axis of the electron gun (electron gun Tip11)), or the electron beam device on which the electron source device is mounted (FIGS. 18 and 19) And the optical axis 2 of reference) are adjusted so as to coincide with each other. This adjustment method is as described above.

By controlling the amount of current supplied to the hollow coil 13 and the direction of the current, the spirality of the electron spiral wave 21 generated at the lower part of the electron gun Tip11 and the sign of the spiral degree can be controlled.

The electron gun Tip11 and the hollow coil 13 are respectively arranged at positions where the distribution of magnetic flux lines is asymmetrical with respect to the plane Q (see FIG. 11 or FIG. 13) including the electron emission region. If it is in such an arrangement relationship, the electron gun Tip11 and the hollow coil 13 may be arranged in any way, but as shown in FIG. 21, the tip of the electron gun Tip11, that is, the (electron emitting part region) is a coil. It is preferable to dispose the electron gun Tip 11 in the hollow coil 13 so as to be positioned below the central portion of the hollow coil 13. In the central part of the hollow coil 13, magnetic flux lines 81 parallel to the axis 2 of the electron gun Tip 11 are easily generated. The magnetic flux line 81 spreads as the electron beam 27 emitted from the tip of the electron gun Tip 11 spreads, and further spreads upward in the figure beyond the bottom surface of the hollow coil 13. Thus, if it is in the said positional relationship, it is thought that the magnetic flux line 81 crosses easily the curved surface which the track | orbit of the electron beam 27 defines in the narrow space range of an electron gun part (refer FIG. 12, FIG. 13). In other words, a spiral wave can be generated without propagating the electron beam 27 emitted from the tip of the electron gun Tip11 for a long distance downward as long as it is in the above positional relationship.

FIG. 22 is a cross-sectional view showing another configuration of the electron source section of Configuration Example 2. In FIG. 22, an electron beam extraction electrode 30 is further provided in the configuration of the electron source section shown in FIG. This electron gun is a field emission electron gun. The configuration shown in FIG. 22 is an example. For example, the shape of the extraction electrode 30 may be a Butler type. In this case, the brightness of the electron beam can be improved. Thus, the characteristics of the electron beam can be improved by devising the shape of the extraction electrode 30. Moreover, addition of a configuration part implemented by a normal field emission electron gun, such as further addition of a configuration part such as another electrode (not shown) or a device for an electrode shape, or a change in the shape thereof may be appropriately performed.

Further, the extraction electrode 30 is made of a magnetically transparent (low magnetic permeability) metal material so that the presence of the extraction electrode 30 does not affect the density and distribution of the magnetic flux in the space in which the electron beam 27 propagates. It is preferable. For example, it can be easily handled by adopting copper or the like as the material of the extraction electrode 30.

<Configuration example 3>
FIG. 23 is a cross-sectional view showing Configuration Example 3 of the electron source section of the present embodiment. FIG. 23 is an example in which the hollow coil 13 of the electron source section described with reference to FIG. 21 in the column of the configuration example 2 is formed as a hollow coil 13 divided into two upper and lower stages.

Thus, the two hollow coils 13 are arranged as a set. For example, a Helmholtz type coil pair is used. Thus, even when the hollow coils 13 (coil pairs) arranged in two upper and lower stages are used, a hollow portion is provided in the middle portion between the two hollow coils 13 where the tip of the electron gun Tip 11 is located. Magnetic flux lines 81 that are substantially parallel to the central axis of the coil 13 are generated. Therefore, similarly to the case of the configuration example 2, the magnetic flux lines 81 cross the curved surface defined by the trajectory of the electron beam 27 in the space range of the electron gun portion, and a spiral wave can be generated.

Thus, when the hollow coil 13 is divided and arranged, the magnetic flux generated is smaller than in the case of the configuration example 2 (FIG. 21), but in order to generate a spiral wave with a spiral degree of 1, the magnetic flux is Since two flux quanta are sufficient, there is no problem in generating a spiral wave. In this way, an electron beam having a sufficient degree of spiraling can be generated.

In this configuration example, since the hollow coils 13 are arranged in two upper and lower stages, the upper and lower hollow coils 13 can be individually controlled. For example, it is possible to control the overall magnetic flux line distribution by making a difference in the density of the magnetic flux lines generated in the upper and lower hollow coils 13. In this configuration example, since the hollow coil 13 is arranged in two upper and lower stages, a space is generated between the hollow coils 13. For this reason, compared with the case of the structural example 2 (FIG. 21), the Joule heat which generate | occur | produces in each hollow coil 13 can be released outside, and the temperature rise of an electron gun part can be suppressed. Further, other constituent members can be arranged using the space between the hollow coils 13. For example, a correction unit for correcting the magnetic field application axis, an adjustment unit for adjusting the electron beam emission site, and the like can be disposed between the hollow coils 13. Specifically, an electrode or a minicoil can be arranged in the space as the correction unit (see FIGS. 16 and 17). The correction method of the magnetic field application axis and the adjustment method of the electron beam emission site and the like are as described above.

FIG. 24 is a cross-sectional view showing another configuration of the electron source section of Configuration Example 3. 24, in addition to the configuration of the electron source section shown in FIG. 23, an electron beam extraction electrode 30 is further provided. This electron gun is a field emission electron gun. The configuration shown in FIG. 24 is an example. For example, the shape of the extraction electrode 30 may be a Butler type. In this case, the brightness of the electron beam can be improved. Thus, the characteristics of the electron beam can be improved by devising the shape of the extraction electrode 30. Moreover, addition of a configuration part implemented by a normal field emission electron gun, such as further addition of a configuration part such as another electrode (not shown) or a device for an electrode shape, or a change in the shape thereof may be appropriately performed.

FIG. 25 is a cross-sectional view showing another configuration of the electron source section of Configuration Example 3. FIG. 25 shows an example in which the electron beam extraction electrode 30 shown in FIG. 24 is extended between the hollow coils 13. As described above, the extraction electrode 30 for the electron beam can be provided by utilizing the space between the hollow coils 13.

Also in the configuration shown in FIG. 25, as described above, the presence of the extraction electrode 30 is magnetically transparent (permeability) so as not to affect the density and distribution of the magnetic flux in the space in which the electron beam 27 propagates. The lead electrode 30 is preferably made of a metal material having a low

<Configuration example 4>
FIG. 26 is a cross-sectional view showing a configuration example 4 of the electron source section of the present embodiment. In FIG. 26, a magnetic path (spiral wave generating magnetic path) 37 is provided outside the hollow coil 13. The hollow coil 13 is arranged so that a magnetic field can be applied in the optical axis direction, and the magnetic path 37 is configured using a material having high magnetic permeability such as permalloy and is provided outside the hollow coil 13.

The hollow coil 13 and the outer magnetic path 37 have the same configuration as the electromagnetic lens. Therefore, higher density magnetic flux lines 81 can be generated at the position of the electron gun Electron Tip 11 inside the hollow coil 13 as compared with the case of the configuration examples 2 and 3. This configuration is particularly suitable for generating a spiral wave having a high degree of spiral.

Further, according to this configuration example, the positional relationship between the magnetic path 37 and the electron gun Tip 11 can be mechanically aligned with high accuracy. Therefore, a spiral wave can be generated by improving the accuracy of the phase distribution of the spiral shape together with the spiral degree. Furthermore, since the magnetic path 37 is used, it is difficult to be affected by fluctuations in the distribution of magnetic flux lines due to electromagnetic induction from the outside. For this reason, it is expected to realize an electron source section that generates a spiral wave with stable characteristics.

<Configuration example 5>
FIG. 27 is a cross-sectional view showing a configuration example 5 of the electron source section of the present embodiment. In FIG. 27, a magnet 38 is provided instead of the hollow coil 13 and the magnetic path 37 in the configuration example 2 (FIG. 21). For example, the magnet 38 is arrange | positioned in the up-and-down part (magnetic pole part) of the magnetic path 37 of the structural example 2 (FIG. 21). In this configuration example, a magnetic flux distribution can be created at the tip of the electron gun Tip11 without using a coil. As the magnet material, an SmCo magnet or an NdFeB magnet that can generate a strong magnetic field can be used. By using such a magnet material, it is possible to create a strong magnetic flux distribution at the tip of the electron gun Tip11 even in a configuration without using a coil.

Further, according to this configuration example, other components can be arranged using the space between the magnets 38. For example, a correction unit for correcting the magnetic field application axis, an adjustment unit for adjusting the electron beam emission site, and the like can be disposed between the hollow coils 13. Specifically, an electrode or a minicoil can be arranged in the space as the correction unit (see FIGS. 16 and 17). The correction method of the magnetic field application axis and the adjustment method of the electron beam emission site and the like are as described above.

Further, the amount of magnetic flux can be controlled by the method described in the configuration example 1. For example, as a magnetic material used for the magnet 38, a magnetic material whose amount of magnetic flux changes with temperature is used, and a heating unit such as a heater is provided around the magnet 38. In this case, the amount of magnetic flux (magnetic flux distribution) can be controlled by changing the temperature of the magnet 38 with a heater. A magnetic field generator such as a coil connected to the magnet 38 may be provided. In this case, the amount of magnetic flux flowing between the magnets 38 can be controlled by the magnetic field generator.

Also, the polarity of magnetic flux lines can be reversed by the following method. For example, a strong magnetic field greater than the reversal magnetization of the magnetic body is applied from the outside to the magnetic body constituting the magnet 38. In addition, a magnetic field having a reverse polarity is applied in a state where the magnetic body constituting the magnet 38 is heated to a temperature equal to or higher than the Curie temperature of the magnetic body. In this case, the magnetic field may be weak.

In the configuration example 5, it is possible to stably generate a spiral wave having a predetermined spiral degree. Therefore, it is suitable for use as an electron source section (electron beam generator) for an electron beam apparatus that uses a helical wave having a predetermined degree of spiral. Further, since no electric power is required to generate the magnetic flux lines 81, power saving of the apparatus can be achieved.

As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in the above-described embodiment, the electron beam is a spiral wave and has been described as an example applied to an electron beam apparatus such as an electron microscope. However, the present invention is applied to charged particles such as ions in addition to electrons. Is possible. In other words, the charged particle beam can be used as a helical wave and applied to a charged particle beam generator or a charged particle beam device.

DESCRIPTION OF SYMBOLS 1 ... Electron source, 2 ... Optical axis, 3 ... Sample, 5 ... Objective lens, 8 ... Detection recording surface, 9 ... Diffraction image (small angle electron diffraction image), 10 ... Observation point, 11 ... Electron gun Tip, 12 ... Electron Wire injection part, 13 ... Coil (hollow coil), 14 ... Mini coil, 15 ... Parallel plate electrode, 17 ... Control system, 19 ... Control system, 21 ... Spiral wave, 22 ... Spiral axis, 23 ... Plane wave, 24 ... Rupture ( Yin), 26 ... Wavefront, 27 ... Electron beam (electron orbit), 29 ... Magnetic field application axis, 30 ... Extraction electrode, 33 ... Spiral phase plate, 35 ... Diffraction image, 37 ... Magnetic path, 38 ... Magnet, 39 ... Control System, 40 ... Acceleration tube, 41, 42 ... Lens (condenser lens), 47, 48 ... Control system, 49 ... Control system, 51 ... System control computer, 52 ... Monitor, 53 ... Interface, 59 ... Control system, 61, 62 ... Lens (intermediate lens), 63, 4 ... Lens (projection lens), 66, 67, 68, 69 ... Control system, 76 ... Image data monitor, 77 ... Recording device, 78 ... Controller, 79 ... Detector, 81 ... Magnetic flux line, 83 ... Monopole, 84 ... Reverse polarity monopole, 87 ... Superconducting cylinder, 88 ... Magnetic body, 89 ... Solenoid, 91 ... Diffraction grating (edge dislocation grating), 97 ... Ring diffraction spot, 99 ... Dot diffraction spot, ABCD ... curved surface, I ... path (orbit), II ... path (orbit), l ... distance from electron source to detection surface, Q ... plane, r ... distance from optical axis, RSP1 ... ring-shaped spot, RSP2 ... ring Spot, Ss ... region (area)

Claims

A charged particle beam generator having a charged particle source installed in a magnetic field,
The application direction of the magnetic field is parallel to the axis of the charged particle source,
A charged particle beam generator configured to adjust a strength of the magnetic field so that a charged particle beam emitted from the charged particle source has a helical phase distribution.
The charged particle beam generator according to claim 1, wherein a magnetic flux amount in a region of the magnetic field through which the charged particle beam is transmitted is an integral multiple of a quantized magnetic flux.
2. The charged particle beam generator according to claim 1, wherein an amount of magnetic flux in a region of the magnetic field through which the charged particle beam passes is an integral multiple of 4.14 × 10 −15 Wb.
The magnetic field is a magnetic field having an axisymmetric magnetic flux distribution,
The charged particle beam generator according to claim 1, wherein an axis of the magnetic field is adjusted to coincide with an axis of the charged particle source.
The magnetic field is a magnetic field having an axisymmetric magnetic flux distribution,
When a distance from the axis of the charged particle source is r on a plane that includes a part of the charged particle source and is perpendicular to the axis of the charged particle source,
The charged particle beam generator according to claim 1, wherein the magnetic flux distribution of the magnetic field is inversely proportional to the square of the distance r.
A charged particle beam apparatus having a charged particle source,
The charged particle source is installed in a magnetic field;
The application direction of the magnetic field is parallel to the axis of the charged particle beam device,
A charged particle beam apparatus, wherein the charged particle beam emitted from the charged particle source has a helical phase distribution by adjusting the intensity of the magnetic field.
The charged particle beam apparatus according to claim 6, wherein a magnetic flux amount in a region of the magnetic field through which the charged particle beam is transmitted is an integral multiple of a quantized magnetic flux.
The charged particle beam apparatus according to claim 6, wherein an amount of magnetic flux in a region of the magnetic field through which the charged particle beam passes is an integral multiple of 4.14 × 10 −15 Wb.
The magnetic field is a magnetic field having an axisymmetric magnetic flux distribution,
The charged particle beam apparatus according to claim 6, wherein an axis of the magnetic field is adjusted to coincide with an axis of the charged particle beam apparatus.
The magnetic field is a magnetic field having an axisymmetric magnetic flux distribution,
When a distance from the axis of the charged particle source is r on a plane that includes a part of the charged particle source and is perpendicular to the axis of the charged particle source,
The charged particle beam device according to claim 6, wherein the magnetic flux distribution of the magnetic field is inversely proportional to the square of the distance r.
7. The charged particle beam apparatus according to claim 6, wherein the charged particle beam having the helical phase distribution irradiates the sample with an opening angle of 1 × 10 −6 rad or less.
The charged particle beam apparatus according to claim 6, wherein the charged particle beam having the helical phase distribution irradiates the sample, and a charged particle diffraction image of the sample is obtained with a camera length of 80 m or more.
A charged particle source;
A magnetic field generator for generating a magnetic field in a direction parallel to an emission direction of a charged particle beam emitted from the charged particle source, and generating a magnetic field for immersing the charged particle source;
A sample holder,
An irradiation optical system for irradiating the charged particle beam to a sample mounted on the sample holding device;
A sample processing method using a charged particle device comprising:
By adjusting the intensity of the magnetic field generated by the magnetic field generator, the charged particle beam is modulated into a charged particle beam having a helical phase distribution,
A sample processing method, wherein the sample is processed by irradiating the sample with a charged particle beam having a helical phase distribution by the irradiation optical system.
14. The sample processing method according to claim 13, wherein the amount of magnetic flux in a region of the magnetic field through which the charged particle beam is transmitted is an integral multiple of the quantized magnetic flux.
The magnetic field is a magnetic field having an axisymmetric magnetic flux distribution,
The sample processing method according to claim 13, wherein an axis of the magnetic field is adjusted to coincide with an axis of the charged particle source.
The magnetic field is a magnetic field having an axisymmetric magnetic flux distribution,
When a distance from the axis of the charged particle source is r on a plane that includes a part of the charged particle source and is perpendicular to the axis of the charged particle source,
The sample processing method according to claim 13, wherein the magnetic flux distribution of the magnetic field is inversely proportional to the square of the distance r.
A charged particle source;
A magnetic field generator for generating a magnetic field in a direction parallel to an emission direction of a charged particle beam emitted from the charged particle source, and generating a magnetic field for immersing the charged particle source;
A sample holder,
An irradiation optical system for irradiating the charged particle beam to a sample mounted on the sample holding device;
A sample observation method using a charged particle device comprising:
By adjusting the intensity of the magnetic field generated by the magnetic field generator, the charged particle beam is modulated into a charged particle beam having a helical phase distribution,
A sample observation method for observing an image or diffraction image of the sample by irradiating the sample with the charged particle beam having a helical phase distribution by the irradiation optical system.
The sample observation method according to claim 17, wherein the amount of magnetic flux in a region of the magnetic field through which the charged particle beam is transmitted is an integral multiple of the quantized magnetic flux.
The magnetic field is a magnetic field having an axisymmetric magnetic flux distribution,
The sample observation method according to claim 17, wherein an axis of the magnetic field is adjusted to coincide with an axis of the charged particle source.
The magnetic field is a magnetic field having an axisymmetric magnetic flux distribution,
When a distance from the axis of the charged particle source is r on a plane that includes a part of the charged particle source and is perpendicular to the axis of the charged particle source,
The sample observation method according to claim 17, wherein the magnetic flux distribution of the magnetic field is inversely proportional to the square of the distance r.