JP6518442B2 - Electron detector and scanning electron microscope - Google Patents

Description

  The present invention relates to an electron detection apparatus and a scanning electron microscope, and more particularly to an electron detection apparatus for detecting secondary electrons emitted from a sample and a scanning electron microscope including the electron detection apparatus.

  When a sample is irradiated with a primary electron beam (electron beam), secondary electrons obtained by exciting atoms on the surface are emitted from the sample. The surface of the sample can be observed by detecting the secondary electrons. Therefore, a scanning electron microscope for observing the surface of a sample is provided with an electron detection device for detecting secondary electrons emitted from the sample.

  By the way, when a sample is irradiated with a primary electron beam, secondary electrons are emitted radially from the sample around the optical axis of the primary electron beam. On the other hand, the conventional electron detection device is arranged at only one place in the direction around the optical axis of the primary electron beam, and detects only a part of secondary electrons emitted radially from the sample. (See, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 11-67139

  However, in the case of a generally used cylindrical electronic detection device conventionally used, the detection surface for detecting secondary electrons is circular, and the size thereof is limited. Only part of the electrons can be detected. Therefore, since the amount of signal that can be detected is small, the S / N, which is the ratio of the signal based on secondary electrons to noise, is bad.

  Then, an object of this invention is to provide the scanning electron microscope provided with the electronic detection apparatus which can acquire the good detection signal of S / N, and the said electronic detection apparatus.

In order to achieve the above object, the electronic detection device of the present invention is
An electron detection apparatus for detecting secondary electrons emitted from a sample based on a primary electron beam irradiated to the sample, comprising:
And an annular detection unit configured to surround an optical axis of the primary electron beam and detecting secondary electrons emitted from the sample.
The detection unit is
An annular scintillator unit for converting secondary electrons emitted from the sample into light;
A light detection unit that detects light emitted from the scintillator unit;
A light guide unit for guiding the light emitted from the scintillator unit to the light detection unit;
An annular shield portion provided inside the scintillator portion for stabilizing the potential;
An annular spectroscope provided inside the detection unit and the shield unit for dispersing secondary electrons emitted from the sample in a direction perpendicular to the optical axis of the primary electron beam ;
The scintillator unit is provided so as to surround the optical axis of the primary electron beam, and a surface on which the secondary electrons are incident is formed along a ring parallel to the optical axis of the primary electron beam. Do.
In addition, in order to achieve the above object, a scanning electron microscope of the present invention is characterized by including the electron detection device of the above configuration.

In the electron detection device configured as described above or a scanning electron microscope provided with the electron detection device, the detection surface S of the secondary electrons is a surface parallel to the optical axis of the primary electron beam and annular so as to surround the optical axis. As a result, secondary electrons (electron energy) emitted radially from the sample can be generally detected in the direction around the optical axis. The potential of the primary electron beam is stabilized on the inner side of a scintillator section which is provided to surround the optical axis of the primary electron beam and in which the surface on which the secondary electrons are incident is formed along the ring parallel to the optical axis of the primary electron beam. An annular shield portion is formed. Then, secondary electrons emitted from the sample are dispersed in a direction perpendicular to the optical axis of the primary electron beam by the annular spectroscope provided inside the detection surface S and the shield portion, and converted into light by the scintillator portion. Ru. The light emitted from the scintillator unit is condensed on the light detection unit by the light guide unit, and the light detection unit detects the light.

  According to the present invention, since secondary electrons emitted radially from the sample can be generally detected along the direction around the optical axis of the primary electron beam, the amount of signal that can be detected is increased, and S / N ( It is possible to obtain a detection signal with a good ratio of a signal based on secondary electrons and noise.

It is a schematic block diagram which shows an example of a structure of the scanning electron microscope of this invention. It is a top view which shows the structural example of the electronic detection apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which shows an example of a structure of the annular | circular shaped spectrometer used by the electron detection apparatus which concerns on 1st Embodiment. FIG. 2 is a configuration diagram showing a light guide unit according to a first embodiment. FIG. 7 is a configuration diagram showing a light guide unit according to a second embodiment. It is a top view which shows the structural example of the electronic detection apparatus which concerns on 2nd Embodiment of this invention. It is a circuit diagram which shows an example of a circuit structure of an electrical system containing the circuit which produces | generates the voltage applied to the mesh electrode of each step | stage of the dynode part in the electronic detection apparatus concerning 2nd Embodiment.

  Hereinafter, modes for carrying out the present invention (hereinafter, referred to as “embodiments”) will be described in detail with reference to the drawings. The present invention is not limited to the embodiments, and various numerical values and the like in the embodiments are examples. In the present specification and the drawings, the same components or components having substantially the same functions will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

<Scanning Electron Microscope>
Before describing the electronic detection device of the present invention, a scanning electron microscope of the present invention including the electronic detection device will be described. FIG. 1 is a schematic view showing an example of the configuration of a scanning electron microscope of the present invention.

  As shown in FIG. 1, the scanning electron microscope 1 includes at least an electron optical system 10 and an electron detection device 20, and identifies the sample 2 based on secondary electrons detected by the electron detection device 20. The electron optical system 10 irradiates the sample 2 with a primary electron beam. The electron detection apparatus 20 is a secondary electron detection apparatus that excites atoms on the surface of the sample 2 and detects secondary electrons emitted by irradiating the sample 2 with the primary electron beam by the electron optical system 10.

  The electron optical system 10 includes an electron gun 11, a focusing lens 12, an X-direction scanning deflector 13, a Y-direction scanning deflector 14, an objective lens 15, and the like. The electron gun 11 emits a thin electron beam called an electron probe. The focusing lens 12 is for adjusting the thickness of the electron beam emitted from the electron gun 11, and is, for example, a magnetic field lens utilizing the action of a magnet.

  The X-direction scanning deflector 13 is for scanning the primary electron beam irradiated to the sample 2 in the X direction (left and right direction in the drawing). The Y-direction scanning deflector 14 is for scanning the primary electron beam irradiated to the sample 2 in the Y direction (the direction perpendicular to the paper surface). The electron beam emitted from the electron gun 11 is two-dimensionally scanned by the X-direction scanning deflector 13 and the Y-direction scanning deflector 14. The objective lens 15 is for focusing to determine the final diameter of the primary electron beam to be irradiated to the sample 2 and is made of, for example, a magnetic lens as the focusing lens 12.

  When the sample 2 is irradiated with the primary electron beam, secondary electrons are emitted radially from the sample 2 around the optical axis O of the primary electron beam. The electron detection device 20 detects secondary electrons (electron energy) emitted from the sample 2. Here, the electron detection device 20 is disposed between the sample 2 and the objective lens 15, but the present invention is not limited to this. The electron detection device 20 can be disposed at an arbitrary position in the optical path of the electron optical system 10. It is.

  In addition, the electron detection device 20 is not limited to one configured to directly detect secondary electrons emitted radially from the sample 2. For example, a donut-shaped reflector may be disposed in the optical path along the optical axis O of the electron optical system 10, and secondary electrons emitted from the sample 2 and reflected by the reflector may be detected. Good.

  The detection signal of the electronic detection device 20 is subjected to signal processing such as amplification, for example, and then sent to a display device (not shown) to show the change in brightness according to the amount of secondary electrons to the display device. It is displayed as an image.

<Electronic detection device>
The electron detection device 20 is an electron detection device according to the present invention, and includes an annular detection unit provided to surround the optical axis O of the primary electron beam, for detecting secondary electrons emitted from the sample 2. The detection portion is characterized in that a detection surface (light receiving surface) having a surface parallel to the optical axis O is formed along an annular shape. Here, "parallel" is a meaning including the case of being substantially parallel as well as the case of being strictly parallel to the optical axis O of the primary electron beam, and various variations occurring in design or manufacture The presence of is acceptable. Further, "annular" includes, in addition to annular, rectangular and elliptical shapes.

  When the detection surface of the secondary electrons of the electron detector 20 is formed along an annulus surrounding the optical axis O of the primary electron beam, the secondary electrons (electron energy) emitted radially from the sample 2 It can be detected entirely along the direction around the optical axis O of the electron beam. As a result, the amount of signal that can be detected by the electron detection device 20 is larger than that of the conventional electron detection device in which only a part of electrons can be detected in the direction around the optical axis O. It is possible to obtain a good detection signal of S / N which is the ratio of the signal based on noise to noise. Hereinafter, an embodiment of the electronic detection device of the present invention will be specifically described.

First Embodiment
FIG. 2 is a plan view showing an example of the configuration of the electronic detection device according to the first embodiment of the present invention. As shown in FIG. 2, in the electron detector 20A according to the first embodiment, the detection surface (light receiving surface) S of the secondary electron as the detection unit is a surface parallel to the optical axis O of the primary electron beam. It is annularly formed to surround the optical axis O. That is, the detection surface S is formed over the entire circumference of the annular detection portion, and the detection surface S is also formed in an annular shape. By making the detection surface S annular, the distance from the optical axis O to the detection surface S can be made uniform in the direction around the optical axis O of the primary electron beam, and a detection signal with high accuracy is acquired be able to. Further, an annular spectroscope 30, for example, is disposed inside the detection surface S and between the optical axis O and the like. That is, the annular spectroscope 30 is provided at the center of the electron detection device 20A. The spectroscope 30 disperses the secondary electrons emitted radially from the sample 2 in the direction perpendicular to the optical axis O of the primary electron beam.

(Annular spectrometer)
FIG. 3 is a cross-sectional view showing an example of the configuration of an annular spectroscope. In FIG. 3, the spectroscope 30 has two electrodes 31 and 32 arranged concentrically around the optical axis O (rotation axis Q) and a space defined between the two electrodes 31 and 32. It has two electrodes 33 and 34 of the same potential as the electrodes 31 and 32 provided so as to be closed. Spectroscope 30 is further different from electrode 35 which is provided in a space surrounded by two electrodes 31 and 32 and two electrodes 33 and 34 and which can apply different potentials from these electrodes 31 to 34. And an electrode 36 to which a potential can be applied.

  Each of the electrodes 31 to 36 has a rotationally symmetrical shape having one rotation center axis Q. Therefore, in the case of the configuration example of FIG. 3, the electrodes 31, 32 and 36 are cylindrical surface electrodes, and the electrodes 33, 34 and 35 are annular flat electrodes. Further, a slit 37 is formed in the electrode 34 on the lower surface side, and a slit 38 is formed in the outer electrode 32. Since the electrodes 34 and 32 have a rotationally symmetrical shape with one rotation center axis Q as a center, the slit 37 is an annular slit, and the slit 38 is a cylindrical slit.

  A mesh is stretched in the slit 37. The slit 37 serves as an entrance slit for taking in secondary electrons emitted from the sample 2. The slit 38 is an exit slit that emits the taken-in secondary electrons. By placing an electron emission point R for emitting secondary electrons on the sample 2 on one rotation center axis Q, the rotation center axis Q coincides with the optical axis O of the primary electron beam. Here, "coincidence" means that the rotation central axis Q and the optical axis O of the primary electron beam strictly coincide with each other, and also includes the case where they substantially coincide. The presence of variations in is acceptable.

  In the spectroscope 30 configured as described above, by setting the electrodes 35 and 36 in the space surrounded by the electrodes 31 to 34 to an appropriate potential, the secondary electrons coming from the entrance slit 37 are deflected while being decelerated at first. Under the action, it is subjected to deflection while being accelerated. Here, secondary electrons are emitted from the electron emission point R of the sample 2 at an emission angle θ ± Δθ. The degree of deceleration is stronger as the value of Δθ is larger on the positive side, and as a result, the degree of deceleration is affected by a stronger deflection, and the value of Δθ is larger on the negative side.

  As a result, the secondary electrons emitted from the electron emission point R of the sample 2 at the emission angle θ ± Δθ converge near the electrode 32, and only the secondary electrons within a specific energy range from the exit slit 38 It is emitted in the direction perpendicular to Q. In this manner, the spectroscope 30 disperses the secondary electrons emitted from the electron emission point R of the sample 2 radially in the direction perpendicular to the optical axis O of the primary electron beam (ie, the rotation center axis Q). Can.

  In FIG. 2, on the outside of the exit slit 38 of the spectroscope 30, a shield portion 21 formed in an annular shape to stabilize the potential is provided. The shield unit 21 is constituted by a grid (mesh electrode) kept at the same potential as the outer frame of the spectroscope 30, ie, the ground potential, and the surface on the side of the spectroscope 30 serves as a detection unit for detecting secondary electrons. It becomes the detection surface S. A thin scintillator portion 22 formed in an annular shape is provided on the outside of the shield portion 21. In some cases, a voltage of about several [kV] to about several tens [kV] is applied to the scintillator unit 22. The scintillator portion 22 is held by a scintillator holding material 23 made of a light transmitting material provided on the outer periphery thereof.

  The shield unit 21 shields the potential of the scintillator unit 22 so as not to affect the electric field inside the spectroscope 30. The secondary electrons radially emitted from the exit slit 38 of the spectroscope 30 enter the scintillator section 22 through the shield section 21 made of a grid. The scintillator unit 22 is a fluorescent material, converts incident secondary electrons into light, and radiates the converted light radially through the scintillator holding material 23 made of a light transmitting material.

  The electron detection device 20A according to the first embodiment includes a light detection unit (light detector) 24 and a scintillator as shown in FIGS. 4 and 5 in addition to the shield unit 21, the scintillator unit 22 and the scintillator holding material 23. And a light guide unit 25 for guiding the light emitted from the unit 22 to the light detection unit 24. As the light guide part 25, those of various configurations can be used. Below, the concrete Example of the light guide part 25 is described.

Example 1
FIG. 4 is a configuration diagram showing the light guide unit according to the first embodiment. A plan view is shown in FIG. 4A and a side view is shown in FIG. 4B.

  As shown to FIG. 4A, the light guide part 25 which concerns on Example 1 consists of an elliptical shaped reflecting plate which has two focus. With respect to the light guide portion 25, the spectroscope 30 and the constituent members (the shield portion 21, the scintillator portion 22, etc.) disposed outside thereof have one of the reflecting plates whose center (rotational symmetry axis) is at an elliptical position. Are arranged to be located at the focal point P1 of The light detection unit 24 is formed of a general photomultiplier or the like, and is disposed such that its center is located at the other focal point P2 of the elliptical reflector.

  In the electron detecting device 20A using the light guiding portion 25 formed of the elliptical reflecting plate of the above configuration, the secondary electrons emitted from the exit slit 38 of the spectroscope 30 pass through the mesh of the shielding portion 21 and the scintillator portion 22 The light is converted to light by the scintillator unit 22 and emitted radially. A voltage of several [kV] or more may be applied to the scintillator unit 22 in order to accelerate secondary electrons and enhance the luminous efficiency. However, since the shield portion 21 having the same ground potential as the outer frame of the spectroscope 30 is provided outside the exit slit 38 of the spectroscope 30, the electric field inside the spectroscope 30 is applied to the scintillator portion 22. Not affected by the The light radially emitted from the scintillator unit 22 is reflected by the elliptical reflecting surface (reflecting plate) of the light guide 25 as shown by the arrows in the drawing.

  At this time, the spectroscope 30 and the constituent members (the shield portion 21, the scintillator portion 22 and the like) disposed outside the spectroscope 30 are disposed such that the centers thereof are located at one focal point P1 of the elliptical reflector. Therefore, based on the secondary electrons emitted annularly around the rotational symmetry axis of the spectroscope 30, substantially all of the light emitted radially from the scintillator portion 22 is collected at the other focal point P2. Since the light detection unit 24 is disposed at the position of the focal point P2, substantially all of the radial light based on the secondary electrons emitted from the spectroscope 30 can be efficiently detected by the light detection unit 24. it can. The detection signal of the light detection unit 24 is supplied as an image signal to a display (not shown).

(Example 2)
FIG. 5 is a configuration diagram illustrating a light guide unit according to a second embodiment. As shown in FIG. 5, the light guide 25 according to the second embodiment is formed of a parabolic reflector having an opening 25a. With respect to the light guide portion 25, the spectroscope 30 and members (the shield portion 21, the scintillator portion 22 etc.) surrounding the spectroscope 30 have their centers (rotational symmetry axes) located at the focal point P3 of the parabolic reflector. Will be placed. The light detection unit 24 is formed of a plate-shaped photomultiplier or the like, and is disposed in the vicinity of the opening 25a of the parabolic reflector so as to close the opening.

  In the electron detecting device 20A using the light guiding portion 25 formed of the parabolic reflector of the above configuration, the secondary electrons emitted from the exit slit 38 of the spectroscope 30 pass through the mesh of the shielding portion 21 and the scintillator portion The light is converted into light by the scintillator unit 22 and emitted radially. About the effect | action of the shield part 21 of a grounding potential, it is the same as that of said case. The light radially emitted from the scintillator unit 22 is reflected by the parabolic reflecting surface (reflecting plate) of the light guide 25 as indicated by the arrows in the drawing.

  At this time, the spectroscope 30 and the constituent members (the shield portion 21, the scintillator portion 22 and the like) disposed outside the spectroscope 30 are disposed such that the centers thereof are located at the focal point P3 of the parabolic reflector. Therefore, almost all of the radial light emitted from the spectroscope 30 becomes parallel light and travels to the opening 25a of the parabolic reflector. Since the light detection unit 24 is disposed so as to close the opening 25 a, substantially all of the radial light emitted from the spectroscope 30 can be efficiently detected by the light detection unit 24. The detection signal of the light detection unit 24 is supplied as an image signal to a display (not shown).

  As described above, according to the electronic detection device 20A according to the first embodiment, the detection surface S of the secondary electrons is a plane parallel to the optical axis O of the primary electron beam and so as to surround the optical axis O Since it is provided in an annular shape, secondary electrons (electron energy) emitted radially from the sample 2 can be generally detected around the optical axis O.

  In the first embodiment, the light guide 25 is formed of an elliptical reflector, and the spectroscope 30 and the component members disposed on the outside of the spectroscope 30 at the position of the focal point P1 of the elliptical reflector ((1) The shield unit 21 and the scintillator unit 22 are disposed, and the light detection unit 24 is disposed at the position of the other focal point P2. Thereby, substantially all of the light emitted from the scintillator unit 22 can be condensed on the light detection unit 24 based on the secondary electrons emitted from the spectroscope 30.

  Further, in the second embodiment, the light guide 25 is formed of a parabolic reflector, and the spectroscope 30 and the components disposed on the outside of the spectrometer 30 at the position of the focal point P3 of the parabolic reflector ( The shield unit 21 and the scintillator unit 22 are disposed, and the plate-like light detection unit 24 is disposed in the opening. Accordingly, it is possible to condense almost all of the light emitted from the scintillator unit 22 on the plate-like light detection unit 24 based on the secondary electrons emitted from the spectroscope 30.

  Thus, in both the first embodiment and the second embodiment, almost all of the light emitted from the scintillator unit 22 based on the secondary electrons emitted radially from the spectroscope 30 is detected by the light detection unit 24. It can be detected efficiently. As a result, for secondary electrons (electron energy) emitted from the sample 2, the amount of signal that can be detected by the electron detection device 20A is larger than that of the conventional electron detection device, so a detection signal with good S / N is obtained. it can.

Second Embodiment
FIG. 6 is a plan view showing a configuration example of an electronic detection device according to a second embodiment of the present invention.

  As shown in FIG. 6, in the electron detection device 20B according to the second embodiment, the detection surface (light receiving surface) S of the secondary electrons as the detection portion is a surface parallel to the optical axis O of the primary electron beam. It is formed along an annular shape, preferably an annular shape, so as to surround the optical axis O. In addition, a spectroscope 30 is disposed inside the detection surface S and between the optical axis O and the optical axis O. That is, the spectroscope 30 is provided at the center of the electron detection device 20B. The spectroscope 30 disperses the secondary electrons emitted radially from the sample 2 in the direction perpendicular to the optical axis O of the primary electron beam. As the spectroscope 30, as in the electron detection device 20A according to the first embodiment, the ring-shaped spectroscope (see FIG. 3) described above can be used.

  On the outside of the exit slit 38 of the spectroscope 30, a shield portion 21 formed in an annular shape is provided. The shield portion 21 is formed of a grid maintained at the same potential as the outer frame of the spectroscope 30, ie, the ground potential, and the inner surface thereof is a detection surface S for detecting secondary electrons. On the outside of the shield portion 21, a ring-shaped dynode portion 26 having a function as an electron multiplier is provided.

  The dynode portion 26 has a multi-stage configuration in which a plurality of mesh electrodes whose annularly formed surface is covered with an electron emitting material are arranged concentrically around the optical axis O of the primary electron beam. A positive voltage, which becomes higher in order from the optical axis O side (inner side) to the outer side, is applied to the mesh electrodes of each stage of the dynode portion 26.

  FIG. 7 shows an example of a circuit configuration of an electrical system including a circuit for generating a voltage to be applied to the mesh electrodes of each stage of the dynode unit 26. As shown in FIG. Here, the multi-stage dynode unit 26 is configured to have n stages, that is, n (n stages) mesh electrodes (dynodes). Then, the voltages applied to the n-stage mesh electrodes are D1, D2, ..., Dn (D1 <D2 <... <Dn) in order from the inside to the outside.

  As shown in FIG. 7, the circuit 28 for generating a voltage to be applied to the dynode unit 26 includes, for example, n + 1 resistance elements R1, R2, ..., Rn + 1 between ground (GND) and the DC power supply HV. Are connected in series to form a voltage divider circuit. Then, in the voltage dividing circuit 28, voltages D1, D2,... Sequentially increasing from the inside to the outside from the connection nodes N1, N2, ..., Nn of the resistance elements R1, R2, ..., Rn + 1. , Dn are derived and applied to the mesh electrodes of each stage.

  In the dynode section 26 in which voltages D1, D2, ..., Dn are applied to the mesh electrodes of each stage, when secondary electrons are incident on the inner first mesh electrode (dynode), a plurality of secondary electrons are generated. Is released. When secondary electrons emitted from the first stage mesh electrode are incident on the second stage mesh electrode, more secondary electrons are emitted. The secondary electrons are multiplied by repeating this process one after another.

  On the outside of the dynode portion 26, an anode portion 27 which is an example of an electron collection portion for collecting electrons is annularly provided. A current according to the amount of collected secondary electrons flows through the anode portion 27. As shown in FIG. 7, a current measuring device 29 is connected between the anode 27 and the DC power supply HV. Then, in accordance with the amount of electrons collected by the anode unit 27, the current measuring device 29 measures the current flowing to the anode unit 27.

  In the electron detection device 20B according to the second embodiment of the above configuration, the secondary electrons emitted from the exit slit 38 of the spectroscope 30 pass through the mesh of the shield portion 21 and then the mesh of the first stage of the dynode portion 26 It is accelerated by the positive potential applied to the electrode (dynode). In addition, since the shield portion 21 having the same ground potential as the outer frame of the spectroscope 30 is provided outside the exit slit 38 of the spectroscope 30, the mesh of the first stage is applied to the electric field inside the spectroscope 30. It is not affected by the voltage applied to the electrodes.

  The secondary electrons colliding with the mesh electrode of the dynode portion 26 cause a multiplication effect which increases as going outward. Then, secondary electrons multiplied by the outermost mesh electrode are collected at the anode unit 27. As a result, a current corresponding to the amount of secondary electrons flows through the anode portion 27, and this current is detected by the current measuring device 29.

  As described above, according to the electron detection device 20B according to the second embodiment, the detection surface S of the secondary electron is a surface parallel to the optical axis O of the primary electron beam and so as to surround the optical axis O Since it is provided in an annular shape, secondary electrons (electron energy) emitted radially from the sample 2 can be generally detected around the optical axis O. Then, in the electron detection device 20B according to the second embodiment, the secondary electrons detected on the annular detection surface S are multiplied by the annular dynode portion 26, and the annular anode portion disposed at the outermost side. It collects at 27 and detects it as a current.

  Thereby, secondary electrons (electron energy) emitted from the sample 2 can be efficiently detected. As a result, for secondary electrons (electron energy) emitted from the sample 2, the signal amount that can be detected by the electron detection device 20B is larger than that of the conventional electron detection device, so a detection signal with good S / N is obtained it can.

<Modification>
The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the invention described in the claims.

  For example, in each of the above embodiments, the spectrometer 30 is provided, and secondary electrons obtained by dispersing the secondary electron in a direction perpendicular to the optical axis O of the primary electron beam by the spectrometer 30 are detected by the annular detection surface S However, the present invention is also applicable to the configuration without the spectroscope 30. The detection surface S is formed continuously over the entire circumference of the annular detection portion, but may be formed to include a portion in which the detection surface is not formed.

  Specifically, for example, secondary electrons (electron energy) emitted radially from the sample 2 may be directly detected by the detection surface S. Further, a donut-shaped reflection plate is disposed in the light path of the electron optical system 10, and secondary electrons emitted from the sample 2 and reflected by the reflection plate are detected by the annular detection surface S. Good.

  In each of the above-described embodiments, the constituent members such as the shield portion 21, the scintillator portion 22, the dynode portion 26, the anode portion 27 and the like disposed outside the spectroscope 30 are annular, and the detection surface S is annular. However, the present invention is not limited to an annular shape, and may be, for example, a rectangular annular shape.

  DESCRIPTION OF SYMBOLS 1 ... scanning electron microscope, 2 ... sample, 10 ... electron optical system, 11 ... electron gun, 12 ... focusing lens, 13 ... X-direction scanning deflector, 14 ... Y-direction scanning deflector, 15 ... objective lens, 20 ... electron detection device, 20A ... electron detection device according to the first embodiment, 20B ... electron detection device according to the second embodiment, 21 ... shield unit, 22 ... scintillator unit, 24 ... light detection unit (light detector), Reference Signs List 25 light guiding part 26 dynode part 27 anode part 30 spectroscope S detection surface of secondary electrons (light receiving surface)

Claims (5)

An electron detection apparatus for detecting secondary electrons emitted from a sample based on a primary electron beam irradiated to the sample, comprising:
And an annular detection unit configured to surround an optical axis of the primary electron beam and detecting secondary electrons emitted from the sample.
The detection unit is
An annular scintillator unit for converting secondary electrons emitted from the sample into light;
A light detection unit that detects light emitted from the scintillator unit;
A light guide unit for guiding the light emitted from the scintillator unit to the light detection unit;
An annular shield portion provided inside the scintillator portion for stabilizing the potential;
An annular spectroscope provided inside the detection unit and the shield unit for dispersing secondary electrons emitted from the sample in a direction perpendicular to the optical axis of the primary electron beam ;
The scintillator unit is provided so as to surround the optical axis of the primary electron beam, and a surface on which the secondary electrons are incident is formed along a ring parallel to the optical axis of the primary electron beam. Electronic detection device. The light guiding portion comprises an elliptical reflector having two focal points,
The shield part and the scintillator part are arranged to be located on one focal point of the elliptical reflector,
The light detecting unit, the electronic detection device according to claim 1, characterized in that it is arranged to be located on the other focus of the reflector of the elliptical shape. The light guide comprises a parabolic reflector with an aperture having a focal point,
The shield part and the scintillator part are arranged to be located on the focal point of the parabolic reflector.
The light detecting unit, the electronic detection device according to claim 1, characterized in that arranged near the opening of the reflector of the parabolic shape. The shape of the said scintillator part is an annular ring shape centering on the optical axis of the said primary electron beam. The electron detection apparatus of any one of Claim 1 to 3 characterized by the above-mentioned. An electron optical system that irradiates and scans a sample with a primary electron beam;
An electron detection apparatus that detects secondary electrons emitted from the sample based on a primary electron beam irradiated to the sample by the electron optical system;
The electronic detection device is
And an annular detection unit configured to surround an optical axis of the primary electron beam and detecting secondary electrons emitted from the sample.
The detection unit is
An annular scintillator unit for converting secondary electrons emitted from the sample into light;
A light detection unit that detects light emitted from the scintillator unit;
A light guide unit for guiding the light emitted from the scintillator unit to the light detection unit;
An annular shield portion provided inside the scintillator portion for stabilizing the potential;
An annular spectroscope provided inside the detection unit and the shield unit for dispersing secondary electrons emitted from the sample in a direction perpendicular to the optical axis of the primary electron beam ;
The scintillator unit is provided so as to surround the optical axis of the primary electron beam, and a surface on which the secondary electrons are incident is formed along a ring parallel to the optical axis of the primary electron beam. Scanning electron microscope.

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