JP6104756B2 - Electron spectrometer - Google Patents

Description

  The present invention relates to an electron spectrometer.

  Electron spectrometers such as X-ray photoelectron spectrometers and Auger electron spectrometers are known as devices for analyzing solid surfaces.

  For example, Patent Document 1 discloses an angle-resolved electron spectrometer that includes an aperture that is disposed on a diffraction surface of a condenser lens and that limits an angle to incident electrons.

  Specifically, in the angle-resolved electron spectrometer disclosed in Patent Document 1, electrons that have entered the incident lens system from the intake port are collected by the previous focusing lens, and are separated from the sample by the diffraction surface aperture disposed at the diffraction surface position. An angle limit is given to the emitted electrons. Then, the electrons that have passed through the diffractive surface aperture and whose angle is limited are retarded (decelerated) by the subsequent lens and converged. Angle-resolved electron spectroscopic measurement is performed by performing energy spectroscopy on the electrons that have passed through the subsequent aperture by means of a hemispherical analyzer.

JP 2001-266787 A

  Here, photoelectrons are emitted from the sample to be measured at various angles. However, in the angle-resolved electron spectrometer of Patent Document 1, only a photoelectron having a specific angle can be tackled with an analyzer, and the sample has to be tilted in order to capture photoelectrons having other angles. For this reason, there is a problem that adjustment of the apparatus and measurement cannot be easily performed.

  One of the objects according to some aspects of the present invention is to provide an electron spectrometer capable of easily performing angle-resolved photoelectron spectroscopy.

(1) An electron spectrometer according to the present invention is
An electron capture section for capturing electrons emitted from the sample;
An energy spectroscopic unit for selecting energy of electrons captured by the electron capturing unit;
A detection unit for detecting electrons selected by the energy spectroscopic unit;
Including
The electronic capture unit is
A pre-stage lens that captures electrons emitted from the sample;
An aperture disposed behind the front lens;
A first rear lens disposed behind the aperture;
A rear deflection element disposed behind the first rear lens for deflecting electrons;
A second rear lens disposed behind the rear deflection element;
An entrance slit disposed behind the second rear lens;
Have
The first rear lens and the second rear lens form a diffractive surface on the entrance slit ,
The rear stage deflection element is disposed behind the main surface of the combined lens of the first rear stage lens and the second rear stage lens .

  According to such an electron spectroscopic device, the latter stage deflection element deflects the electrons to move the diffractive surface on the entrance slit, and the specific emission from the photoelectrons emitted from the sample at various emission angles. Angle photoelectrons can be selected and made incident on the energy spectroscopic unit. Therefore, for example, angle-resolved photoelectron spectroscopy can be easily performed without performing mechanical control such as tilting the sample.

  According to such an electron spectrometer, it is possible to move the diffraction surface formed by the first rear lens and the second rear lens with a simple configuration.

( 2 ) In the electron spectrometer according to the present invention,
The distance between the aperture and the main surface of the synthetic lens may be equal to the distance between the main surface of the synthetic lens and the entrance slit.

  According to such an electron spectrometer, a diffractive surface can be formed on the entrance slit by the first rear lens and the second rear lens.

( 3 ) In the electron spectrometer according to the present invention,
The rear stage deflection elements may be arranged in multiple stages.

  According to such an electron spectroscopic device, the diffractive surface formed on the entrance slit can be moved in a direction orthogonal to the optical axis of the optical system constituting the electron take-in portion. Therefore, even if the photoelectrons are deflected and the diffraction surface is moved, the photoelectrons can be made incident on the entrance slit in a state of being on the optical axis.

( 4 ) In the electron spectrometer according to the present invention,
The electron take-in unit may include a pre-stage deflecting element that is disposed between the pre-stage lens and the aperture and deflects electrons.

  According to such an electron spectroscopic device, it is possible to deflect photoelectrons emitted from a region of the sample outside the optical axis of the optical system constituting the electron take-in unit and align it with the optical axis. Therefore, photoelectrons emitted from any region of the sample can be measured. In addition, since the front lens can be easily brought close to the sample, the electron capture angle in the front lens can be increased.

( 5 ) In the electron spectrometer according to the present invention,
The pre-stage deflection element may have a deflection center located on a focal plane of the pre-stage lens.

  According to such an electron spectroscopic device, photoelectrons emitted from various regions of the sample can be aligned with the optical axis of the optical system constituting the electron take-in unit.

( 6 ) In the electron spectrometer according to the present invention,
The post-stage deflection element may move a diffraction surface formed by the first post-stage lens and the second post-stage lens.

( 7 ) The electron spectrometer according to the present invention is:
An electron spectrometer having an angle-resolved photoelectron spectroscopy mode and a photoelectron imaging mode,
An electron capture section for capturing electrons emitted from the sample;
An energy spectroscopic unit for selecting energy of electrons captured by the electron capturing unit;
A detection unit for detecting electrons selected by the energy spectroscopic unit;
Including
The electronic capture unit is
A pre-stage lens that captures electrons emitted from the sample;
A front deflection element disposed behind the front lens and deflecting electrons;
An aperture disposed behind the front deflection element;
A first rear lens disposed behind the aperture;
A rear deflection element disposed behind the first rear lens for deflecting electrons;
A second rear lens disposed behind the rear deflection element;
An entrance slit disposed behind the second rear lens;
Have
In the angle-resolved photoelectron spectroscopy mode,
The first rear lens and the second rear lens form a diffractive surface on the entrance slit,
The rear stage deflection element moves a diffraction surface formed by the first rear stage lens and the second rear stage lens,
In the photoelectron imaging mode,
The first rear lens and the second rear lens form an imaging surface on the entrance slit,
The front deflection element, the electrons emitted from the region of the sample outside the optical axis is deflected to match to the optical axis,
The rear stage deflection element is disposed behind the main surface of the combined lens of the first rear stage lens and the second rear stage lens .

  According to such an electron spectroscopic device, in the angle-resolved photoelectron spectroscopic mode, the post-deflecting element deflects electrons, so that photoelectrons having a specific emission angle can be obtained from photoelectrons emitted from the sample at various emission angles. It can select and inject into an energy spectroscopy part. Therefore, angle-resolved photoelectron spectroscopy can be easily performed. In the photoelectron imaging mode, photoelectron imaging can be performed by taking out photoelectrons emitted from the respective regions on the sample by the pre-stage deflection element. Therefore, for example, measurement time can be shortened and measurement accuracy can be improved.

( 8 ) In the electron spectrometer according to the present invention,
The distance between the aperture and the main surface of the synthetic lens may be equal to the distance between the main surface of the synthetic lens and the entrance slit.

( 9 ) In the electron spectrometer according to the present invention,
The rear stage deflection elements may be arranged in multiple stages.

( 10 ) In the electron spectrometer according to the present invention,
The pre-stage deflection element may have a deflection center located on a focal plane of the pre-stage lens.

( 11 ) In the electron spectrometer according to the present invention,
The energy spectroscopic unit may include an electrostatic hemispherical analyzer.

The figure which shows the structure of the electron spectrometer which concerns on this embodiment. The figure which shows the optical system in the angle-resolved photoelectron mode of the electron spectrometer which concerns on this embodiment. The figure which shows the optical system in the angle-resolved photoelectron mode of the electron spectrometer which concerns on this embodiment. The figure which shows the optical system in the photoelectron imaging mode of the electron spectrometer which concerns on this embodiment. The figure which shows the optical system in the photoelectron imaging mode of the electron spectrometer which concerns on this embodiment. The figure which shows an example of the optical state of each orbit in the optical system of the electron spectrometer which concerns on this embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are essential constituent requirements of the present invention.

1. Electron Spectrometer First, an electron spectrometer according to the present embodiment will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of an electron spectrometer 100 according to the present embodiment. Here, an example in which the electron spectroscopic device 100 is a photoelectron spectroscopic device that performs measurement by performing energy spectroscopy on electrons emitted by irradiating a substance with light (for example, X-rays) will be described.

  The electron spectroscopy apparatus 100 includes an angle-resolved photoelectron mode and a photoelectron imaging mode. The angle-resolved photoelectron mode is a mode for performing angle-resolved photoelectron spectroscopy. Angle-resolved photoelectron spectroscopy is a method for obtaining kinetic energy information of photoelectrons by determining and measuring photoelectron emission angles. The photoelectron imaging mode is a mode in which photoelectron spectroscopic measurement is performed and mapped for each predetermined region of the sample.

  As shown in FIG. 1, the electron spectroscopy apparatus 100 includes a primary radiation source 2, an electron capture unit 4, an energy spectroscopy unit 6, and a detection unit 8.

  The primary radiation source 2 irradiates the sample S with electromagnetic waves having a predetermined energy. Thereby, electrons (photoelectrons) are emitted from the sample S by the photoelectric effect. The electromagnetic wave irradiated by the primary radiation source 2 is, for example, X-rays, ultraviolet rays or the like. Hereinafter, an example in which the electron spectrometer 100 is an X-ray photoelectron spectrometer that measures the energy of photoelectrons generated by irradiating the sample S with X-rays will be described.

  The electron capture unit 4 captures photoelectrons emitted from the sample S. The electron capturing unit 4 guides photoelectrons emitted from the sample S to the energy spectroscopic unit 6. The electron capture unit 4 decelerates the photoelectrons and guides them to the energy spectroscopic unit 6. High energy resolution can be obtained by decelerating photoelectrons in the electron take-in unit 4.

  The electronic capture unit 4 includes an optical system 40. The optical system 40 includes a front optical system 40 a from the sample S to the aperture 44, and a rear optical system 40 b disposed behind the aperture 44. Here, the rear means the downstream side of the photoelectron flow.

  The front-stage optical system 40 a includes a front-stage lens (first input lens) 42, a front-stage deflection element 43, and an aperture 44.

  The front lens 42 captures photoelectrons emitted from the sample S. The front lens 42 is disposed closest to the sample S in the optical system 40. The front lens 42 is arranged so that the distance a between the sample S and the main surface of the front lens 42 is smaller than the distance b between the main surface of the front lens 42 and the aperture 44. That is, the preceding optical system 40a is an enlargement system. The front lens 42 forms an image plane on the aperture 44. The imaging surface is a surface on which a real image is formed, and is a real space.

  The front stage deflection element 43 is disposed behind the front stage lens 42. The front stage deflection element 43 is disposed between the front stage lens 42 and the aperture 44.

  The pre-stage deflection element 43 deflects photoelectrons in a two-dimensional manner using an electric field, a magnetic field, or a superimposed field thereof. The front stage deflection element 43 has, for example, a 4-pole or 8-pole deflection electrode. In the pre-stage deflection element 43, a voltage is applied to each deflection electrode, thereby generating an electrostatic field between the deflection electrodes and deflecting photoelectrons.

  The deflection center of the front stage deflection element 43 is located at the focal plane (rear side focal plane) f42 of the front stage lens. Here, the focal plane is a plane that passes through the focal point of the lens and is perpendicular to the optical axis of the lens. The deflection center is a point where an optical axis of a photoelectron before deflection (a virtual line representing a photoelectron passing through the entire system) and an optical axis of a photoelectron after deflection intersect. That is, the photoelectrons are deflected around the deflection center by the pre-stage deflection element 43. In the illustrated example, the deflection center of the front stage deflection element 43 and the focal point of the front stage lens 42 coincide with each other. For example, by placing the center of the deflection electrode constituting the front stage deflection element 43 at the position of the focal length f of the front stage lens 42, the deflection center of the front stage deflection element 43 can be made to coincide with the focal plane f42 of the front stage lens 42. it can.

  The pre-stage deflection element 43 can deflect the photoelectrons emitted from the region of the sample S outside the optical axis of the optical system 40 and align it with the optical axis (see FIG. 5). Since the deflection center of the front stage deflection element 43 is located on the focal plane f42 of the front stage lens 42, the photoelectrons emitted from various regions of the sample S can be aligned with the optical axis. By controlling the pre-stage deflection element 43, photoelectrons emitted from a desired region on the sample S can be measured. The pre-stage deflection element 43 is controlled by, for example, a control unit (not shown).

  The aperture 44 is disposed behind the front deflection element 43. The aperture 44 is disposed at a position where an imaging plane is formed by the front lens 42. The aperture 44 cuts unnecessary photoelectrons from the front lens 42 and the front deflection element 43. The aperture 44 passes only photoelectrons near the optical axis of the optical system 40 and shields other photoelectrons.

  The rear optical system 40b includes a first rear lens (second input lens) 46, rear deflection elements 47a and 47b, a second rear lens (retarding lens) 48, and an entrance slit 49. ing.

  The first rear lens 46 is disposed behind the aperture 44.

The rear stage deflection elements 47 a and 47 b are disposed behind the first rear stage lens 46. The rear optical system 40b includes a plurality (two in the illustrated example) of rear deflection elements 47a and 47b. The rear deflection elements 47a and 47b are arranged in multiple stages (two stages in the illustrated example). The first rear stage deflection element 47 a is disposed behind the first rear stage lens 46. The second rear stage deflection element 47b is disposed behind the first rear stage deflection element 47a. The rear stage deflection elements 47 a and 47 b are arranged behind the main surface P of the combined lens of the first rear stage lens 46 and the second rear stage lens 48.

  The rear stage deflection elements 47a and 47b deflect the photoelectrons in a two-dimensional manner using an electric field, a magnetic field, or a superimposed field thereof. The rear stage deflection elements 47a and 47b have, for example, 4-pole or 8-pole deflection electrodes.

  The rear optical system 40b performs two-stage deflection using the two-stage rear deflection elements 47a and 47b. Specifically, the photoelectrons are deflected by the first second stage deflection element 47a at the first stage, and the photoelectrons deflected by the second second stage deflection element 47b at the second stage are turned back (see FIG. 3). By controlling the rear deflection elements 47a and 47b, the diffraction surface on the entrance slit 49 formed by the rear lenses 46 and 48 can be moved. The rear deflection elements 47a and 47b are controlled by a control unit (not shown).

  The second rear lens 48 is disposed behind the second rear deflection element 47b. The second rear lens 48 decelerates photoelectrons.

  The first rear lens 46 and the second rear lens 48 form a diffractive surface on the entrance slit 49 in the angle-resolved photoelectron mode. The diffractive surface is, for example, a surface on which a diffraction pattern is formed, and is an inverse space. The first rear lens 46 and the second rear lens 48 form an imaging surface on the entrance slit 49 in the photoelectron imaging mode.

  The lenses 42, 46, and 48 that constitute the optical system 40 are electronic lenses. Each of the lenses 42, 46, and 48 may be an electric field type electrostatic lens or a magnetic field type electromagnetic lens. The lens action of each lens 42, 46, 48 is controlled by, for example, a control unit (not shown).

  In the angle-resolved photoelectron mode, the distance L1 between the aperture 44, the first rear lens 46, and the main surface P of the second rear lens 48 is between the main surface P of the synthetic lens and the entrance slit 49. Is equal to the distance L2. In the electron spectroscopic device 100, in the angle-resolved photoelectron mode, the main surface P of the combined lens of the first rear lens 46 and the second rear lens 48 is disposed at an intermediate position between the aperture 44 and the incident slit 49, The rear lenses 46 and 48 are set so that a diffractive surface is formed. The rear stage deflection elements 47a and 47b are arranged behind the main surface P of the synthetic lens.

  The entrance slit 49 is disposed behind the second rear lens 48. The incident slit 49 limits the photoelectrons incident on the energy spectroscopic unit 6. The entrance slit 49 is equipotential with the second rear lens 48, for example.

  The energy spectroscopic unit 6 performs energy sorting (energy spectroscopy) on the photoelectrons captured by the electron capturing unit 4. The energy spectroscopic unit 6 can select the photoelectrons that have been decelerated by the second post-stage lens 48 and have passed through the entrance slit 49, and take out electrons having specific energy.

The energy spectroscopic unit 6 includes, for example, an electrostatic hemispherical analyzer. In the electrostatic hemispherical analyzer, for example, different voltages are applied to the outer sphere electrode and the inner sphere electrode to form a spherically symmetric electric field. Then, when electrons of equal energy are incident at various angles from one point of a spherically symmetric electric field, they are rotated by 180 degrees and then converged to substantially the same point. On the other hand, when an electron having a different energy is incident on a spherically symmetric electric field, it is focused on another point. Therefore, energy spectroscopy can be performed by causing electrons having a certain energy width to enter such a field. That is, in the electrostatic hemispherical analyzer, the position of electrons detected on the emission surface corresponds to the energy (kinetic energy) of electrons.

  The electrons taken out by the energy spectroscopic unit 6 are accelerated by, for example, the acceleration lens 7 and enter the detection unit 8.

  The detection unit 8 detects the photoelectrons selected by the energy spectroscopic unit 6. The detection unit 8 is, for example, a microchannel detector (MCP Detector) configured to include a microchannel plate (MCP: Micro-Channel Plate). The MCP can detect incident electrons and the like two-dimensionally and multiply them for each channel, and has a predetermined position resolution. The detection unit 8 includes, for example, a two-dimensional detector that combines an MCP, a fluorescent screen, and a CCD camera.

  In the electron spectroscopic device 100, for example, based on the detection result of the detection unit 8, a photoelectron energy spectrum is generated.

2. Operation of Electron Spectrometer Next, the operation of the electron spectrometer 100 will be described with reference to the drawings. Here, the angle-resolved photoelectron spectroscopy mode will be described first, and then the photoelectron imaging mode will be described.

2.1. Angle-Resolved Photoelectron Spectroscopy Mode FIGS. 2 and 3 are diagrams showing the optical system 40 in the angle-resolved photoelectron mode of the electron spectrometer 100. FIG. 2 shows a state where the rear deflection elements 47a and 47b are not operated, and FIG. 3 shows a state where the rear deflection elements 47a and 47b are operated.

  The front lens 42 takes in photoelectrons emitted from the sample S and forms an image plane on the aperture 44. The photoelectrons that have passed through the aperture 44 enter the first rear lens 46.

  The first rear lens 46 and the second rear lens 48 form a diffractive surface (reverse space) on the entrance slit 49. The entrance slit 49 allows only photoelectrons emitted at specific angles (azimuth angle and polar angle) to pass, and shields photoelectrons emitted at other angles. As described above, the incident slit 49 can take out photoelectrons emitted at a specific angle and make them incident on the energy spectroscopic unit 6.

  At this time, as shown in FIG. 3, the rear deflection elements 47a and 47b deflect the photoelectrons, whereby the diffraction plane formed on the entrance slit 49 can be moved. Thereby, the emission angle of the photoelectron taken out by the entrance slit 49 can be selected. That is, by controlling the deflection of photoelectrons by the rear stage deflection elements 47a and 47b, the emission angle of the photoelectrons taken out by the entrance slit 49 can be arbitrarily selected. Therefore, in the angle-resolved photoelectron spectroscopy mode, photoelectrons having a desired emission angle can be incident on the energy spectroscopic unit 6.

  For example, when the diffraction pattern of the sample S is formed on the diffraction surface on the entrance slit 49, the subsequent deflection elements 47 a and 47 b move the diffraction pattern by moving the diffraction surface formed on the entrance slit 49. A desired diffracted wave can be selected by the incident slit 49 and can be incident on the energy spectroscopic unit 6.

  Further, as shown in FIG. 3, since the rear stage deflection elements 47a and 47b are arranged in two stages, the diffractive surface formed on the entrance slit 49 is set in a direction orthogonal to the optical axis of the optical system 40. Can be moved. Therefore, even if the photoelectrons are deflected and the diffraction surface is moved, the photoelectrons can be made incident on the entrance slit 49 while being in the optical axis of the optical system 40.

  The photoelectrons that have passed through the entrance slit 49 are subjected to energy selection by the energy spectroscopic unit 6 and detected by the detection unit 8.

  Thus, in the angle-resolved photoelectron spectroscopy mode, the first rear lens 46 and the second rear lens 48 form a diffractive surface on the entrance slit 49, and the rear deflectors 47a and 47b move the diffractive surface, thereby causing photoelectrons. The discharge angle can be determined and measured.

2.2. Photoelectron Imaging Mode FIGS. 4 and 5 are diagrams showing the optical system 40 in the photoelectron imaging mode of the electron spectrometer 100. FIG. 4 shows a state where the pre-stage deflection element 43 is not operated, and FIG. 5 shows a state where the pre-stage deflection element 43 is operated. In FIGS. 4 and 5, illustration of the rear deflection elements 47a and 47b is omitted.

  The optical system 40a in the previous stage uses an enlargement system (a <b), and increases the capture angle of photoelectrons emitted from the sample S. The front optical system 40a is, for example, the same as the angle-resolved photoelectron spectroscopy mode described above.

  Since the magnifying system is used in the optical system 40 a in the previous stage, most of the photoelectrons emitted from the sample S are cut by the aperture 44. The photoelectrons after passing through the aperture 44 are imaged on the entrance slit 49 by the first rear lens 46, whereby a high-resolution photoelectron image can be acquired. At this time, the optical system 40b in the subsequent stage can also acquire a photoelectron image with higher spatial resolution by using an enlargement system. Thus, in the photoelectron imaging mode, the optical system 40b in the subsequent stage forms an imaging surface (real space) on the entrance slit 49.

  As shown in FIG. 5, the pre-stage deflection element 43 can deflect the electrons emitted from the region S <b> 2 of the sample S outside the optical axis of the optical system 40 and align it with the optical axis of the optical system 40. At this time, the photoelectrons emitted from the region other than the region S2 of the sample S are shifted from the optical axis of the optical system 40 and do not pass through the aperture 44. For example, the photoelectrons emitted from the region S 1 on the optical axis of the optical system 40 are deflected by the pre-stage deflection element 43 so as to deviate from the optical axis of the optical system 40 and do not pass through the aperture 44. In this way, by controlling the deflection of the photoelectrons by the pre-stage deflection element 43, the photoelectrons emitted from the respective regions on the sample S can be taken in each region. At this time, the primary radiation source 2 may irradiate the entire surface on the sample S or may irradiate each region on the sample S.

  The photoelectrons that have passed through the entrance slit 49 are subjected to energy selection by the energy spectroscopic unit 6 and detected by the detection unit 8.

  Thus, in the photoelectron imaging mode, photoelectron imaging can be performed by capturing the photoelectrons emitted from the respective regions on the sample S by the pre-stage deflection element 43 for each region.

  Similarly, in the angle-resolved photoelectron spectroscopy mode, measurement may be performed by taking photoelectrons emitted from an arbitrary region of the sample S using the pre-stage deflection element 43.

3. Optical System of Electron Spectrometer Next, the optical system 40 of the electron spectrometer 100 according to the present embodiment will be described in detail. FIG. 6 is a diagram illustrating an example of an optical state of each of the trajectories Traj1 and Traj2 in the optical system 40 of the electron spectrometer 100.

  The focal length f of the front lens 42 is expressed as follows by optical calculation.

Focal length _{f 2} of the first second-stage lens 46 and the focal length of the second second-stage lens 48 and _{f r,} the combined focal length _{f 0} of the subsequent lens 46 and 48 is expressed as follows.

The main surface of the combined lens of the first rear lens 46 and the second rear lens 48 is disposed at an intermediate position between the aperture 44 and the entrance slit 49. Therefore, the distance _{r ap} from the optical axis in the aperture 44, the emission angle _r'ap, and the distance from the optical axis in the entrance slit 49 _{r Slit,} angle _r'Slit is expressed as follows. Incidentally, the distance from the optical axis in the sample surface at the time of photoelectrons emitted and _{r sample,} the emission angle of _r'sample.

3.1. Angular resolution The trajectory Traj1 of electrons that are emitted perpendicularly from the sample surface and pass through the end (X = −r ₀ ) of the aperture 44 is calculated using the above equations (1) and (2).

Originally, on the diffractive surface on the entrance slit 49, the distance r _slit from the optical axis in the entrance slit 49 must be zero. However, the electrons passing through the position of X = −r _{0 on} the surface of the aperture 44 are imaged on the entrance slit 49 with r _{1_slit} not being 0 as described above. Let this deviation amount be Δh.

  Next, an electron trajectory Traj2 that is emitted from the optical axis with an inclination of a small angle Δα and imaged at the position of Δh of the entrance slit 49 is calculated using the above equations (1) and (2).

The following equation is obtained under the condition that the amount of blur due to positional deviation from the sample surface (emits an angle α ₀ and passes through the end of the aperture 44) is equal to the amount of blur at α ₀ + Δα (emits from the optical axis on the sample surface). (However, here, calculation is made in the case of α ₀ = 0).

  Thus, the angular resolution Δα can be defined by the above equation (4).

From equation (4), it can be seen that the angular resolution improves as the radius r _{0 of the} aperture 44 is decreased and the focal length f of the front lens 42 is increased.

  For example, when the diameter of the aperture 44 is 0.6 mmφ and an electron spectrometer having an angular resolution of 0.2 deg is desired, the above equation (4) is 0.2 × (π / 180) = 0.3 / f. Become. Therefore, the optical design of the front lens 42 is performed so that the focal length f of the front lens 42 is 87.5 mm.

3.2. Relationship between the imaging position on the entrance slit for each emission angle and its correction method Next, the relationship between the imaging position on the entrance slit 49 for each emission angle of electrons emitted from the optical axis and its correction method explain.

When electrons from a sample surface on the optical axis is emitted by alpha _0, the distance _{r Slit} from the optical axis in the entrance slit 49, the angle _r'Slit is expressed as follows.

Next, when electrons are emitted from the sample surface at an angle α ₀ and pass through the end (X = −r ₀ ) of the aperture 44 and form an image on the entrance slit 49, the distance r _slit from the optical axis in the entrance slit 49. , Angle r ′ _slit is expressed as follows.

  Here, the size of the diffraction surface and the size of the entrance slit 49 are defined.

The size D _diff of the diffractive surface at the entrance slit 49 is defined by the capture angle α ₀ by the front lens 42, the size d ₀ of the aperture 44, and the like. In consideration of imaging of electrons in the ± α ₀ direction with respect to the optical axis, the size D _diff of the diffractive surface is expressed by the following equation (5).

Regarding the minimum size D _{slit_min} of the entrance slit 49, there is a blur amount due to the diffraction surface due to the angular resolution Δα, and this blur amount must take into account the amount of deviation Δh of electrons that have passed through both directions of ± r _{0 in} the aperture 44. Therefore, the minimum size D _{slit_min} of the entrance slit 49 is expressed by the following formula (6) by doubling the deviation amount Δh.

If the angle resolution Δα remains constant and the size D _slit of the entrance slit 49 is to be increased, the optical system of the front lens 42 is enlarged (a is reduced and b is increased) from the above equation (6). Te, it may be increased composite focal length f _0. If the combined focal length f ₀ is too small, the angle α at the time of incidence into the energy spectroscopic unit 6 becomes _larger than r ′ 4 — _slit , which is not preferable because it is affected by aberrations in the energy spectroscopic unit 6. .

A deviation amount from the center of the optical axis generated at the emission angle α ₀ from the optical axis of the sample surface is deflected by two stages at the rear stage deflection elements 47a and 47b and corrected. The amount of correction at this time is as follows.

  In the rear stage deflection elements 47a and 47b, by swinging back so as to be horizontal on the optical axis, electrons emitted at any angle on the sample surface can be taken into the energy spectroscopic unit 6 for each emission angle.

  The amount of deviation Δd in the detection unit 8 due to the trajectory in the energy spectroscopic unit 6 can be expressed as the following formula (7).

However, X is a position on the X axis in the entrance slit 49, Y is a position on the Y axis in the entrance slit 49, α is an angle with respect to the optical axis when the energy spectroscopic unit 6 is incident, and R _h is the radius of the energy spectral portion 6 (electrostatic hemispherical analyzer), Delta] E is the energy resolution, E _p is the electron pass energy.

If the blur amount Δd after the influence of aberration in the detection unit 8 is not smaller than the minimum size D _{slit_min} of the entrance slit 49, the angle resolution at the time of incidence cannot be defined.

  From the third term of the above equation (7), for example, when it is desired to reduce the influence of the incident angle in the detection unit 8 to 1/10 of the amount of blur at the time of incidence, it is expressed as the following equation (8).

For example, as a specific example, when a = 100 mm, b = 600 mm, r ₀ = 0.3 mm, R _h = 150 mm, Δα = 0.2 deg (0.0035 rad), the amount of movement caused by the aberration due to the incident angle is incident. When it is desired to make the slit size 49 smaller than _1/10 of the minimum size D _{slit_min} of the slit 49, if f ₀ > 48.7 mm using the above equation (8), the energy spectroscopic unit 6 (electrostatic hemispherical analyzer) by the incident angle is used. The influence of aperture aberration can be reduced.

4). Features of Electron Spectrometer The electron spectrometer 100 according to the present embodiment has the following features, for example.

  In the electron spectroscopic device 100, the electron capturing unit 4 includes a front lens 42, an aperture 44 disposed behind the front lens 42, a first rear lens 46 disposed behind the aperture 44, and a first rear lens. 46, rear stage deflection elements 47a and 47b for deflecting electrons, a second rear stage lens 48 arranged behind the rear stage deflection elements 47a and 47b, and an incident arranged behind the second rear stage lens 48. The first rear lens 46 and the second rear lens 48 form a diffractive surface on the entrance slit 49. Therefore, in the electron spectroscopic device 100, the post-stage deflection elements 47a and 47b deflect the electrons so that the emission angle of the photoelectrons taken out by the incident slit 49 can be selected. That is, in the electron spectroscopic device 100, the photo-electrons having a specific emission angle are selected from the photoelectrons emitted from the sample S at various emission angles by deflecting the electrons by the rear-stage deflection elements 47 a and 47 b to select the energy spectroscopic unit. 6 can be made incident.

  As described above, in the electron spectrometer 100, the diffraction angle can be arbitrarily moved by the rear stage deflection elements 47a and 47b, and the emission angle of the photoelectrons can be selected. That is, in the electron spectrometer 100, angle-resolved photoelectron spectroscopy can be performed by electrical control without mechanical control such as tilting and rotation of the sample stage, for example. Therefore, for example, adjustment of the apparatus and measurement can be facilitated, and angle-resolved photoelectron spectroscopy can be easily performed.

  In the electron spectroscopic device 100, the rear deflection elements 47 a and 47 b are arranged behind the main surface P of the combined lens of the first rear lens 46 and the second rear lens 48. Thereby, the diffraction surface formed by the first rear lens 46 and the second rear lens 48 can be moved with a simple configuration.

  In the electron spectroscopic device 100, the distance L 1 between the aperture 44 and the main surface P of the composite lens of the rear lenses 46 and 48 is the distance between the main surface P of the composite lens of the rear lenses 46 and 48 and the entrance slit 49. Equal to L2. Accordingly, a diffractive surface can be formed on the entrance slit 49 by the first rear lens 46 and the second rear lens 48.

  In the electron spectrometer 100, the rear stage deflection elements 47a and 47b are arranged in multiple stages. Thereby, the diffractive surface formed on the entrance slit 49 can be moved in a direction orthogonal to the optical axis of the optical system 40. Therefore, even if the photoelectrons are deflected and the diffraction surface is moved, the photoelectrons can be made incident on the entrance slit 49 while being in the optical axis of the optical system 40.

In the electron spectroscopic device 100, the electron take-in unit 4 includes a pre-stage deflection element 43 that is disposed between the pre-stage lens 42 and the aperture 44 and deflects electrons. Thereby, the electrons emitted from the region of the sample S outside the optical axis of the optical system 40 can be deflected and aligned with the optical axis of the optical system 40. Therefore, photoelectrons emitted from any region of the sample S can be measured.

  Further, since the front stage deflection element 43 is disposed behind the front stage lens 42, the front stage lens is compared with the case where the front stage deflection element 43 is disposed in front of the front stage lens 42 (upstream side of the electron flow). 42 can be easily brought close to the sample S. This is because the pre-stage deflection element 43 is not provided between the pre-stage lens 42 and the sample S, so that a mechanical arrangement can be afforded. By bringing the front lens 42 closer to the sample S, the photoelectron capture angle in the front lens 42 can be increased, and the detection efficiency can be increased.

  In the electron spectroscopic device 100, the deflection center of the front stage deflection element 43 is located at the focal plane of the front stage lens 42. As a result, photoelectrons emitted from various regions of the sample S outside the optical axis of the optical system 40 can be aligned with the optical axis of the optical system 40.

  The electron spectrometer 100 includes an angle-resolved photoelectron spectroscopy mode and a photoelectron imaging mode. In the angle-resolved photoelectron spectroscopy mode, the first rear lens 46 and the second rear lens 48 form a diffractive surface on the entrance slit 49. The rear deflection elements 47a and 47b move the diffraction surface formed by the first rear lens 46 and the second rear lens 48. In the photoelectron imaging mode, the first rear lens 46 and the second rear lens 48 form an imaging surface on the entrance slit 49, and the front deflection element 43 is a region of the sample S outside the optical axis of the optical system 40. The electrons emitted from are deflected and aligned with the optical axis. Therefore, in the angle-resolved photoelectron spectroscopy mode, the post-deflecting elements 47a and 47b deflect the electrons to select photoelectrons having a specific emission angle from the photoelectrons emitted from the sample S at various emission angles. The light can enter the spectroscopic unit 6. Therefore, angle-resolved photoelectron spectroscopy can be easily performed. Further, in the photoelectron imaging mode, photoelectron imaging can be performed by the front stage deflection element 43 taking out photoelectrons emitted from each region on the sample S. Therefore, for example, measurement time can be shortened and measurement accuracy can be improved.

  As described above, the electron spectrometer 100 can perform measurement in any of the angle-resolved photoelectron spectroscopy mode and the photoelectron imaging mode without mechanical control such as movement, rotation, and tilting of the sample stage.

  Further, in the electron spectroscopic device 100, the difference between the angle-resolved photoelectron spectroscopy mode and the photoelectron imaging mode is that a diffraction surface is formed on the entrance slit 49 or an imaging surface is formed by the first rear lens 46 and the second rear lens 48. That is the difference. Therefore, switching between the two modes is possible by switching the lens action of the rear-stage lenses 46 and 48, and switching between the modes is easy.

  In the above-described embodiment, the example in which the electron spectrometer 100 is an X-ray photoelectron spectrometer that measures the energy of photoelectrons generated by irradiating the sample S with X-rays has been described, but the electron spectrometer according to the present invention is It is not limited to this. The electron spectroscopic device according to the present invention may be, for example, an ultraviolet photoelectron spectroscopic device that uses ultraviolet light as light to be applied to the sample S. Further, for example, an Auger electron spectrometer that measures the energy of Auger electrons generated by irradiating the sample S with an electron beam may be used.

The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. The present invention also provides:
The structure which has the same effect as the structure demonstrated in embodiment, or the structure which can achieve the same objective is included. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 2 ... Primary source, 4 ... Electron taking part, 6 ... Energy spectroscopic part, 7 ... Accelerating lens, 8 ... Detection part, 40 ... Optical system, 40a ... Front stage optical system, 40b ... Back stage optical system, 42 ... Pre-stage lens, 43... Pre-stage deflection element, 44... Aperture, 46... First post-stage lens, 47 a... First post-stage deflection element, 47 b. Electron spectrometer

Claims (11)

An electron capture section for capturing electrons emitted from the sample;
An energy spectroscopic unit for selecting energy of electrons captured by the electron capturing unit;
A detection unit for detecting electrons selected by the energy spectroscopic unit;
Including
The electronic capture unit is
A pre-stage lens that captures electrons emitted from the sample;
An aperture disposed behind the front lens;
A first rear lens disposed behind the aperture;
A rear deflection element disposed behind the first rear lens for deflecting electrons;
A second rear lens disposed behind the rear deflection element;
An entrance slit disposed behind the second rear lens;
Have
The first rear lens and the second rear lens form a diffractive surface on the entrance slit ,
The post-stage deflection element is an electron spectroscopic device arranged behind a main surface of a synthetic lens of the first rear stage lens and the second rear stage lens . In claim 1 ,
The electron spectroscopic device, wherein a distance between the aperture and the main surface of the synthetic lens is equal to a distance between the main surface of the synthetic lens and the entrance slit. In claim 1 or 2 ,
The post-stage deflection element is an electron spectrometer arranged in multiple stages. In any one of Claims 1 thru | or 3 ,
The electron spectroscopic device, wherein the electron take-in unit includes a pre-stage deflection element that is disposed between the pre-stage lens and the aperture and deflects electrons. In claim 4 ,
The electron spectroscopic device, wherein the front deflection element has a deflection center located on a focal plane of the front lens. In any one of Claims 1 thru | or 5 ,
The post-stage deflection element is an electron spectroscopic device that moves a diffraction surface formed by the first post-stage lens and the second post-stage lens. An electron spectrometer having an angle-resolved photoelectron spectroscopy mode and a photoelectron imaging mode,
An electron capture section for capturing electrons emitted from the sample;
An energy spectroscopic unit for selecting energy of electrons captured by the electron capturing unit;
A detection unit for detecting electrons selected by the energy spectroscopic unit;
Including
The electronic capture unit is
A pre-stage lens that captures electrons emitted from the sample;
A front deflection element disposed behind the front lens and deflecting electrons;
An aperture disposed behind the front deflection element;
A first rear lens disposed behind the aperture;
A rear deflection element disposed behind the first rear lens for deflecting electrons;
A second rear lens disposed behind the rear deflection element;
An entrance slit disposed behind the second rear lens;
Have
In the angle-resolved photoelectron spectroscopy mode,
The first rear lens and the second rear lens form a diffractive surface on the entrance slit,
The rear stage deflection element moves a diffraction surface formed by the first rear stage lens and the second rear stage lens,
In the photoelectron imaging mode,
The first rear lens and the second rear lens form an imaging surface on the entrance slit,
The front deflection element, the electrons emitted from the region of the sample outside the optical axis is deflected to match to the optical axis,
The post-stage deflection element is an electron spectroscopic device arranged behind a main surface of a synthetic lens of the first rear stage lens and the second rear stage lens . In claim 7 ,
The electron spectroscopic device, wherein a distance between the aperture and the main surface of the synthetic lens is equal to a distance between the main surface of the synthetic lens and the entrance slit. In claim 7 or 8 ,
The post-stage deflection element is an electron spectrometer arranged in multiple stages. In any one of Claims 7 thru | or 9 ,
The electron spectroscopic device, wherein the front deflection element has a deflection center located on a focal plane of the front lens. In any one of Claims 1 thru | or 10 ,
The energy spectroscopic unit is an electron spectroscopic device including an electrostatic hemispherical analyzer.

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