JPH0754686B2 - Simultaneous measurement device for energy and angular distribution - Google Patents

Description

TECHNICAL FIELD The present invention relates to an energy / angle distribution simultaneous measurement apparatus for simultaneously measuring an energy spectrum and angle distribution information of charged particles excited / emitted from a sample surface.

[Conventional technology]

X-ray photoelectron spectroscopy and Auger electron spectroscopy measure the energy spectrum of excited and emitted electrons by irradiating a sample with soft X-rays or electron beams, but the composition analysis of the surface and surface layer of solid materials It has come to be widely used as a method and a chemical state analysis method.

It is known that the emission angle distributions of these photoelectrons and Auger electrons with respect to the sample give the depth distribution of the composition in the surface layer and the film thickness of the surface thin film. give. Furthermore, the present inventors have revealed that the photoelectron emission angle distribution of a single crystal sample exhibits a photoelectron diffraction phenomenon that gives knowledge about the crystallinity and atomic structure of the surface layer, and thus the importance of measuring the photoelectron angular distribution becomes important. It is rising.

FIG. 4 is a diagram showing a configuration outline of a conventional photoelectron spectrometer, and FIG.
The figure is a diagram showing an outline of the configuration of a one-dimensional multi-channel photoelectron spectrometer relating to a polar angle. In the figure, 21 and 31 are electrostatic deflection analyzers, 22 and 32 are outer electrodes, 23 and 33 are inner electrodes, 24
Reference numerals 34 and 34 are samples, 25 and 35 are detectors, 26 is an X-ray generator, 27 is a deceleration lens, 28 and 36 are entrance slits, 29 and 37 are exit slits, and 38 is polar angle distribution information.

In FIG. 4, a hemispherical type analyzer 21 is a hemispherical type analyzer 21 which is covered with two hemispherical type electrodes such as Owan, and is attached to each outer electrode.
22 and the inner electrode 23, the outer electrode 22 has a negative potential, the inner electrode
This is a so-called electrostatic deflection type analyzer in which a positive potential is applied to 23.
In this hemispherical type analyzer 21, when photoelectrons excited and emitted by irradiating the sample 24 with X-rays are injected from one side through the entrance slit 28, different orbits are taken due to the difference in energy, and only electrons having a predetermined energy are taken. It can be taken out by converging on the other exit slit 29 regardless of the discharge angle. In other words, it is an energy selection type analyzer that disperses for each energy, and an angle integration type energy spectrum can be obtained by this.

Although the hemispherical analyzer described above has a 180 ° deflection in the direction of energy dispersion, it has also been proposed to use a toroidal surface with a deflection angle of 135 ° to enable one-dimensional multi-channel measurement of polar angles. . FIG. 5 shows the outline of the configuration. This is a toroidal surface analyzer
By deflecting 31 to 135 °, the detector 35 detects polar angle distribution information 38 relating to predetermined energy.

[Problems to be solved by the invention]

However, since the photoelectron spectrometer shown in FIG. 4 mainly focuses on energy analysis, there is a problem that it takes a long time to measure the polar angle distribution. That is, in this case, for example, by injecting photoelectrons from the entrance slit at a constant narrow solid angle, information about a certain energy and a certain polar angle and azimuth angle is taken out, and this angle is sequentially changed by biaxial rotation of the sample. Then, the same measurement is repeated to obtain the angular distribution. As described above, in the photoelectron spectrometer shown in FIG. 4, the angle distribution cannot be obtained unless the angle of the sample is changed and the same measurement is repeated, and the number of times of measurement becomes extremely large, which requires a long measurement time.

Further, in the case of the example using the 135 ° deflection analyzer shown in FIG. 5, it is possible to obtain the polar angle distribution of a certain energy on the arc, but when obtaining the energy spectrum, the electric field is changed. Since it has to be swept, there is a problem that the number of times of measurement becomes very large and a long measurement time is required.

After all, with the above-mentioned conventional one, it was not possible to simultaneously measure the energy dispersion and the polar angle dispersion by using any photoelectron spectrometer.

The present invention solves the above-mentioned problems, and provides energy dispersion while ensuring the polar angle distribution of charged particles excited and emitted from a sample, and determines the energy dispersion direction and the polar angle dispersion direction on the detection surface. It is an object of the present invention to provide an energy / angle distribution simultaneous measurement device that can be made orthogonal to each other.

[Means for solving problems]

Therefore, the present invention provides simultaneous energy / angular distribution measurement for imparting energy dispersion to a charged particle excited and emitted from a sample while maintaining its polar angle distribution and making the energy dispersion direction and the polar angle dispersion direction orthogonal to each other on the detection surface. A device, wherein an inlet and an outlet are provided at a position with a predetermined radius from the central axis, a cross section orthogonal to the central axis is a concentric double arc with a predetermined opening angle, and a cross section including the central axis is from the inlet to the outlet. 180 ° concentricity 2
It consists of an inner electrode and an outer electrode that form a heavy arc, equipped with a toroidal 180 ° deflection analyzer that deflects 180 ° in the axial direction from the inlet to provide energy dispersion, arranges the sample near the inlet side axis, and 2 near the outlet side axis. It is characterized in that a three-dimensional detector is arranged.

[Action]

In the energy / angle distribution simultaneous measurement apparatus of the present invention, the sample is placed near the entrance side axis of the toroidal 180 ° deflection analyzer, and when charged particles excited and emitted from the sample in a predetermined angle range are injected, the toroidal 180 ° deflection is detected. While maintaining the polar angle distribution injected at the inlet by the analyzer, this charged particle is deflected 180 ° toward the outlet to give energy dispersion. Therefore, the two-dimensional detector disposed near the exit side axis can simultaneously obtain energy / angle distribution information in which the energy is dispersed in the axial direction of the two-dimensional plane of the orthogonal coordinate system and the polar angle is dispersed in the direction orthogonal to the axis. Therefore, the energy integration type angle distribution is obtained by integrating and extracting the axial direction, and the angle integration type energy spectrum is obtained by integrating and extracting the direction orthogonal to the axis. Further, by reversing the potential and the polarity applied to the inner electrode and the outer electrode, it can be applied to both positive and negative charged particles.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the energy / angle distribution simultaneous measurement apparatus of the present invention, and FIG. 2 is a sectional view of a toroidal 180 ° deflection analyzer. In the figure, 1 is a toroidal 180
Deflection analyzer, 2 outer electrode, 3 inner electrode, 4 sample, 5 detector, 6 analyzer control power supply, 7 DC power supply, 8 two-dimensional position detection operational amplifier, 9 and 10 ADC, 1
1 is a two-dimensional multi-channel counting circuit, and 12 is a microcomputer system.

In FIG. 1, a toroidal 180 ° deflection analyzer 1
Is composed of an outer electrode 2 and an inner electrode 3, which are different from the conventional hemispherical type and have a shape using a half of the outer circumference of a donut or a vehicle tire. The divergence angle is generally about 90 ° to 120 °, which corresponds to the polar angle distribution measurement range, but it is not particularly limited to this range. In this way, the outer electrode 2 and the inner electrode 3 are provided with an inlet and an outlet at a position with a predetermined radius from the central axis, and the cross section orthogonal to the central axis is a concentric double arc with a predetermined opening angle, and the central axis is the same. The included cross section forms a concentric double arc of 180 ° from the inlet to the outlet. Then, an electric potential is applied to each of the outer electrode 2 and the inner electrode 3 from the analyzer control power source 6, and the sample 4 and the detector 5 are arranged near the central axis thereof.
Therefore, if you set each coordinate axis of X, Y, Z as shown in the figure,
The central axis is the Y-axis, and the toroidal 180 ° deflection analyzer 1 has a cross section taken along the XZ plane as shown in FIG. 2 (a) and a cross section taken along the YZ plane as shown in FIG. 2 (b). The sample 4 is placed in parallel or substantially parallel to the X axis and the Y axis, and the detector 5 is placed with both the X axis and the Y axis inclined. Detector 5
May be a commercially available two-dimensional position sensitive detector using a microchannel plate, and the DC power supply 7 biases the microchannel plate of the detector 5. The two-dimensional position detection operational amplifier 8 is for performing operational amplification for acquiring a measurement signal corresponding to the two-dimensional position of the detector 5 to obtain energy spectrum and polar angle distribution information, and is an ADC (analog-digital converter). Reference numerals 9 and 10 convert the output signal into a digital signal. Then, this digital signal is counted by the two-dimensional multi-channel counting circuit 11 and taken into the microcomputer system 12 for processing.

With the above configuration, the surface of the sample 4 is excited by irradiating X-rays from the excitation source, and photoelectrons emitted from the surface are injected from the entrance of the toroidal 180 ° deflection analyzer 1. , As shown in the figure, it gives an appropriate energy dispersion while maintaining the polar angle distribution of the photoelectrons e ⁻ . That is, as shown in the drawing, energy dispersion is given in the axial direction, and polar angle dispersion is given in the direction orthogonal thereto. Therefore, the detector 5 can measure its intensity by two-dimensional dispersion in which the energy dispersion direction and the polar angle dispersion direction are orthogonal to each other.

FIG. 3 is a diagram for explaining the correction lens of the toroidal 180 ° deflection analyzer. In the toroidal 180 ° deflection analyzer 1 used in the energy / angle distribution simultaneous measurement device of the present invention, the toroidal 180 ° with a certain spread.
The photoelectrons injected from the entrance of the deflection analyzer 1 are once crossed in the toroidal 180 ° deflection analyzer 1.
Therefore, since it spreads again at the exit, a correction electrode 13 is arranged as shown in FIG. 3 for image formation and angle correction. The correction electrode 13 corrects the photoelectrons that have spread again on the exit side so as to give energy dispersion on the detector 5, and even in polar angular dispersion, if the photoelectrons are directly input to the detector 5, the angle and the detection interval become proportional. It will not be corrected, so correct this. Such a correction electrode (lens) may be arranged between the sample and the analyzer, between the analyzer and the detector, or both in some cases.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the planar detector is used, but the detection surface may be formed of a curved surface that matches the detection direction of the polar angle distribution, so that the linearity of the polar angle distribution may be obtained. To obtain the linearity of polar angle distribution with a flat detector, a lens is arranged in front of the detector for angle correction, or the measurement signal of the detector is subjected to angle correction processing without directly performing angle correction. It may be configured as follows.

Further, although an X-ray generator is used as an excitation source and the sample is irradiated with X-rays, the sample may be irradiated with an electron beam, an ion beam, ultraviolet rays, or the like. Furthermore, not only electrons but also ions may be used as long as they are charged particles that are excited and emitted from the sample and can be deflected by an electric field. In this case, by reversing the polarity of the applied potential, it can be immediately applied to both positive and negative ions, so the energy of ions in ion scattering spectroscopy, which is developing as a surface research method in recent years,
It can also be used to measure angular distribution.

As a method of sweeping the electric field, not only changing the potentials of the inner and outer electrodes of the toroidal 180 ° deflection analyzer,
Instead of this method, the potential of the deceleration lens on the entrance side may be changed.

As described above, the energy / angle distribution simultaneous measurement apparatus of the present invention uses the toroidal 180 ° deflection analyzer to make each of the two dimensions orthogonal to each other on the detection surface correspond to the electron kinetic energy dispersion and the angular dispersion. Since multi-channel measurement can be performed for both energy and angle dimensions through the dimensional position sensitive detector, it enables simultaneous acquisition of multidimensional information such as angular distribution of energy spectrum. In addition, by using multi-channel measurement in only one dimension, it is possible to easily perform high-sensitivity measurement of either the angle integration type energy spectrum or the energy integration type angle distribution.

By the way, the development of high-performance materials and the development of high-density integrated circuit technology largely depend on the development of material evaluation technology. In this material evaluation, it is required to obtain more detailed information about the material substance more quickly. The present invention responds to such a requirement, and since both kinetic energy and angular distribution of electrons can be simultaneously measured in multiple channels, the photoelectron spectroscopy currently utilized for composition of the material surface and chemical state analysis, For Auger electron spectroscopy,
The angle distribution measurement can be performed at the same time, and the overall measurement speed can be dramatically improved. This angular distribution measurement can also provide information on the depth resolution, surface film thickness, or surface atomic structure, so that the composition, chemical state,
Can provide detailed information about the structure at high speed,
It will be a force to further promote the development of advanced materials.

[Effects of the Invention] As is apparent from the above description, according to the present invention, by adopting the toroidal 180 ° deflection analyzer, it is possible to obtain an appropriate value while maintaining the polar angle distribution of the charged particles excited and emitted from the sample. Since energy dispersion can be obtained, the energy dispersion direction and the polar angle dispersion direction can be made orthogonal to each other on the detection surface. Therefore, this orthogonal two-dimensional dispersion enables efficient use of the two-dimensional position detection system, enables simultaneous multi-channel measurement of both energy and angle, and maintains a count rate equal to or higher than that of a commercially available electron spectrometer. In addition, high energy resolution and high angular resolution can be realized. Also, by using a toroidal 180 ° deflection analyzer,
A sufficient distance (space) can be secured between the inlet and the sample and between the outlet and the detector, which is structurally advantageous. Furthermore, since the energy / angle distribution can be simultaneously measured, the energy / angle distribution of all solid angles can be measured at high speed only by rotating the sample about one axis.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the energy / angle distribution simultaneous measurement apparatus of the present invention, FIG. 2 is a sectional view of a toroidal 180 ° deflection analyzer, and FIG. 3 is a description of the correction electrode of the toroidal 180 ° deflection analyzer. FIG. 4 is a diagram showing the outline of the configuration of a conventional photoelectron spectrometer, and FIG. 5 is a diagram showing the outline of the configuration of a one-dimensional multi-channel photoelectron spectrometer relating to polar angles. 1 ... Toroidal 180 ° deflection analyzer, 2 ... Outer electrode, 3 ... Inner electrode, 4 ... Sample, 5 ... Detector, 6 ...
… Analyzer control power supply, 7 …… DC power supply, 8 …… Two-dimensional position detection operational amplifier, 9 and 10 …… ADC, 11 …… Two-dimensional multi-channel counter circuit, 12 …… Microcomputer system, 13 …… Correction electrode .

Claims (1)

[Claims] 1. An energy / angular distribution simultaneous measurement apparatus for imparting energy dispersion to a charged particle excited and emitted from a sample while maintaining its polar angle distribution to make the energy dispersion direction and the polar angle dispersion direction orthogonal to each other on a detection surface. In addition, an inlet and an outlet are provided at a position with a predetermined radius from the central axis, a cross section orthogonal to the central axis is a concentric double arc with a predetermined opening angle, and a cross section including the central axis is 180 degrees from the inlet to the outlet. A toroidal 180 ° that consists of an inner electrode and an outer electrode that form a concentric double circular arc of 180 ° and that deflects 180 ° axially from the inlet to provide energy dispersion.
Equipped with a deflection analyzer, place the sample near the entrance side axis,
Simultaneous measurement system for energy and angle distribution, which has a two-dimensional detector near the exit side axis.