JPH0210646A - charged particle energy analyzer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a charged particle energy analyzer, and particularly to a structure for reducing noise component electrons and varying the energy analysis ability of the energy analyzer.

[Conventional technology]

By irradiation with primary electron beams, ion beams, X-rays, etc.

BACKGROUND ART The technique of obtaining a spectrum by measuring the energy of electrons emitted or scattered from a substance is known as an effective method for identifying the elements constituting the substance and obtaining knowledge about the bonding state. In particular, in the case of Auger electrons and photoelectrons emitted from substances, these methods are called Auger electron spectroscopy and photoelectron spectroscopy, respectively, and are currently widely used.

An energy analyzer is required to measure the energy spectrum of electrons emitted or scattered from the materials described above. Electron energy is O~2keV
When the line flux is relatively low, the electrostatic type is used, and the wire flux is 127° sector type.

Parallel plate type, cylindrical mirror type, 180° hemispherical type, 157° hemispherical type, etc. are available as point bundles.

In conventional energy analyzers, most of the electrons, which have a much different energy than the electrons to be analyzed, hit the inner wall of the electrode of the analyzer, and scattered electrons are generated there.

The structure is such that stray (noise component) electrons such as secondary electrons flow into the detector of the analyzer. Furthermore, the energy analysis ability of the analyzer is adjusted by changing the hole diameter of the detection slit placed just before the detector, but the hole diameter cannot be selected from two or three types.

[Problem to be solved by the invention]

As mentioned above, the prior art does not take into consideration the fact that stray electrons emitted from the inner wall of the electrode of the energy analyzer flow into the detector and the simple structure that can vary the energy resolution of the analyzer. Structural improvements were necessary.

An object of the present invention is to reduce stray electrons in an electron energy analyzer and to improve the energy resolution of the analyzer.

[Means to solve the problem]

The above purpose is to provide a partition plate with a hole through which only the electrons to be analyzed can pass, at the midpoint of the convergence point of the light source, on the trajectory where the aberration is minimized in the energy analyzer;
This is achieved by dividing the analyzer at that position and making the relative position variable.

[Effect]

An electrostatic charged particle energy analyzer uses two parallel planes,
Energy analysis can be performed by forming a dispersion field with a cylindrical or spherical electrode and changing the dispersion field. In the analyzer, the trajectory of the charged particle to be analyzed becomes approximately parallel to the two parallel electrodes at the midpoint position of the convergence point of the electro-optical light source.

Therefore, by providing a partition plate with holes through which only the charged particles to be analyzed can pass, it is possible to remove noise component electrons such as scattered electrons generated when charged particles having a sufficiently different energy than the charged particles to be analyzed hit the electrode. I can do it.

Further, the trajectory of the charged particle whose energy is slightly different from that of the charged particle whose trajectory has the minimum aberration at the position of the partition plate is slightly shifted in angle from the parallel planes of the two parallel electrodes. Therefore.

If the above analyzer is divided at the position of the partition plate, arranged so that the minimum aberration trajectories of the divided analyzers coincide with each other, and the relative distance is made variable, the charged particles with angularly shifted trajectories will be Can be selected according to. That is, the energy resolution of the analyzer can be made variable.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. This is an example in which a cylindrical mirror type energy analyzer is used as an analyzer for electron energy analysis, and FIG. 1 is a diagram showing the structure of the energy analyzer.

1 in Figure 1 is a probe for electron beams, ion beams, X-rays, etc.; 2
is a sample, and 3 is an electron emission point on the sample surface from which electrons are emitted by the probe 1, which corresponds to the electro-optical light source of the cylindrical mirror energy analyzer. Reference numeral 4 denotes an inner cylindrical electrode of the energy analyzer, and 5 an incident side metal mesh slit cut into the inner cylindrical electrode 4 and provided for introducing electrons emitted from the radiation point 3 of the sample 2 into the dispersion field. , 6 has the same structure as the metal mesh slit 5 described above, and is an emission side metal mesh slit provided to allow the electrons to be analyzed to reach the detector. 7 has a central axis passing through the radiation point 3 and is coaxial with the inner cylindrical electrode 4. The outer cylindrical electrode 8 is arranged in the inner cylindrical electrode 4 and the outer cylindrical electrode 7.
This is an end face compensation electrode for compensating the dispersion field of the cylindrical electric field created by the end face, and the face facing the dispersion field is usually a uniform resistance thin film,
Alternatively, it may be made of several concentric rings of thin metal films or a combination of the above. 9 is a cutout plate of the present invention that allows only the electrons to be analyzed to pass through. Reference numeral 10 denotes an electron trajectory that minimizes the aberration at the convergence point of the analyzer using the above-mentioned cylindrical mirror energy, and is called an average trajectory.

Among the electron orbits to be analyzed, reference numeral 11 indicates an electron orbit emitted at the maximum angle of aperture with respect to the central axis of the analyzer at the radiation point 3, and 12 corresponds to the orbit of 11, and an electron emitted at the minimum angle of aperture with respect to the central axis of the analyzer. It is an orbit. 13 is a detection slit, 14 is a convergence point of the energy analyzer, and 15 is a detector, which is usually an electron multiplier.

Electrons are emitted from the sample 2 by the probe 1, and since the sample 2 and the inner circumferential electrode 4 are at ground potential, the sample 2
The electrons emitted from the radiation point 3 spread radially. One of these days,
Only the electrons that have passed through the metal mesh slit 5 cut into the inner circumferential electrode 4 enter the dispersion field created by the negative potential applied to the outer cylindrical electrode 7, and follow different trajectories due to the difference in their kinetic energy. Take. When the negative potential of the outer cylindrical electrode 7 is appropriate, it passes through the metal mesh slit 6 for emission again.

reaches the detector 15. Therefore, by sweeping the negative voltage applied to the outer cylindrical electrode 7 and measuring the electron flow entering the detector 15, it is possible to obtain the energy spectrum of the electrons emitted from the sample.

Next, let us examine in detail the trajectory of the electrons in the analyzer.0 In the cylindrical mirror type electron energy analyzer, the angle of the center axis coaxial with the average trajectory 10 at the radiation point 3 of the trajectory of the electron to be analyzed is 42 Since it is a 0 analyzer that is @18.5', the opening angle (usually 12°
), the orbit of the analyte electron with the largest angle with respect to the central axis is 11, and conversely, the orbit with the smallest angle is 12.

However, if the energy of the electron to be analyzed is sufficiently small, it will collide with the outer surface of the inner circumferential electrode 4, and if it is sufficiently large, it will collide with the inner surface of the outer cylindrical electrode 7.

Naturally, when electrons collide with a metal surface, elastically scattered electrons, inelastically scattered electrons, and secondary electrons are generated. Therefore, there are many chances that these stray electrons, which are not signals, pass through the metal mesh slit 6 for emission and reach the detector 15. In particular, in a cylindrical mirror type analyzer, since the electron trajectory has mirror symmetry with respect to a vertical plane passing through the midpoint position of the radiation point 3 and the convergence point 14, there is a possibility that electrons due to specular reflection will enter the detector 15. will increase.

Therefore, it is necessary to devise ways to block these stray electrons.

If a gap is provided on the plane of symmetry through which only the electrons to be analyzed can pass, like the partition plate 9 of the present invention, it is possible to almost prevent stray electrons from flowing into the detector 15 described above.

In particular, since the average trajectory 10 is perpendicular to the plane of symmetry, there is the advantage that there is no risk of impairing the original energy resolution by inserting the partition plate 9 at this position.

Next, the structure of the partition plate 9 of the present invention will be described.

The surface of the partition plate may not be an insulator or a conductor.

In the case of an insulator, the cylindrical electric field is disturbed by trapping electrons, and conversely, in the case of a conductor, the potential is completely different from the cylindrical electric field.

An example of the structure of the partition plate 9 will be explained with reference to FIG. 16, 17, 18, and 19 in FIG. 2 are thin rings made of metal or metal thin film, 16 is in contact with the outer surface of the inner circumferential electrode 4, and has the same potential as the inner circumferential electrode 4, and 17.18 is a thin ring made of metal or a metal thin film. , is an electrode in the sense of compensating the cylindrical electric field, and it is necessary to apply a new corresponding voltage. 19 is in contact with the inner surface of the outer cylindrical electrode 7 and has the same potential as the same electrode, and 20 is a uniform resistive thin film. .

21 is a reinforcing plate for integrating the partition plate, and the surface is made of a resistive thin film. If the structure is made to be more than 0, the advantage of the partition temporary installation effect described above can be achieved without disturbing the cylindrical electric field. .

As mentioned above, in a cylindrical mirror analyzer, the electron orbit with a specific energy at the position of the plane of symmetry becomes parallel to the central axis. However, the orbits of electrons with slightly different energies have a slight inclination.

Therefore, if the analyzer is divided along the plane of symmetry, the center axis is the same, and the distance between them can be adjusted, the energy resolution can be made variable.

FIG. 3 shows an example of the structure of a variable energy resolution analyzer. In the same figure, 22 is an input side analyzer, 23 is a cylindrical plate that fixes the input side analyzer 22 and has a threaded groove inside the cylinder, and 24 is an output side whose central axis is the same as that of the input side analyzer 22. The analyzer 25 is a cylindrical plate that fixes the emission side analyzer 24, has a threaded groove on the outside of the cylinder, and has a structure that can be incorporated into the cylindrical plate 23 and moved in the direction of the central axis. The example in Fig. 3 shows the input side analyzer 22 and the output side analyzer 2.
4 is small, but if it becomes wide, the electric field at the interval is disturbed, and in order to compensate for this, it is necessary to additionally arrange at least one partition plate 9 coaxially.

The present invention has been explained using a cylindrical mirror type energy analyzer as an example, but the present invention has been explained using a cylindrical mirror type energy analyzer as an example.
Even in a hemispherical or 157° hemispherical energy analyzer, if the partition plate of the present invention is installed at a point on the average orbit between the light source and the convergence point and perpendicular to the average orbit, the amount of stray electrons can be reduced. parts can be cut off. Furthermore, if the analyzer is divided as in the above embodiment, a structure with variable energy resolution can be achieved.

〔Effect of the invention〕

According to the present invention, since stray electrons generated from the inner wall of the electron energy analyzer can be removed, an energy spectrum with less noise components can be obtained. Also, the energy resolution of the electron energy analyzer can be changed continuously.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a cylindrical mirror type electron energy analyzer according to an embodiment of the present invention, FIG. 2 is a plan view showing the structure of the partition plate of the present invention, and FIG. 3 is a view of the variable resolution structure of the present invention. FIG. 2 is a longitudinal cross-sectional view of a cylindrical mirror type energy analyzer.

Claims (1)

[Scope of Claims] 1. In a charged particle energy analyzer with a convergence function equipped with a charged particle detector, electrons on an orbit with the minimum aberration among various charged particle orbits allowed in the analyzer. A partition provided with a hole perpendicular to the minimum aberration trajectory through which only the charged particles to be analyzed can pass, at the midpoint between the optical light source and the convergence point, and equipped with a compensation electrode for not disturbing the dispersion field of the analyzer. A charged particle energy analyzer characterized by inserting a plate. 2. The charged particle energy analyzer having the structure set forth in claim 1 has a structure in which the analyzer is divided at the position of the partition plate and can be moved parallel to the minimum aberration trajectory at that position. A charged particle energy analyzer featuring: