JPH0821367B2 - Charged particle analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to an apparatus suitable for two-dimensionally measuring the energy distribution and the emission angle distribution of charged particles reflected or emitted from a sample by irradiating the sample with an appropriate excitation ray.

B. 2. Description of the Related Art In an apparatus for analyzing a sample by energy analysis of charged particles reflected or emitted from a sample irradiated with an excitation ray, the energy distribution of a charged particle or a certain energy is measured to measure the energy band structure. In the case of measuring the emission angle distribution of particles, it is conventionally necessary to use an analyzer that measures particles in a small solid angle, and move the analyzer over the entire measurement area to obtain the measurement data necessary for analysis. The method of saying is taken. However, according to this method, particles outside the range detected by the analyzer are not detected, which is a waste in measurement, and it takes a long time to perform measurement in the entire measurement range with the required S / N ratio. And In addition, a driving device for moving the analyzer to the entire measurement area is required, which complicates the device.

As an example of a conventional energy analyzer,
FIG. 5 shows a conceptual diagram of the concentric hemisphere analyzer. The outer hemispherical electrode 2 of the hemispherical electrode 1 and the radius R ₂ of the radius R ₁ to match the center O toward the cut on the same side put as in FIG. The charged particles emitted from the sample S are converged on the entrance slit 5 by the lens 4. Charged particles that have entered the space between the inner hemisphere electrode 1 and the outer hemisphere electrode 2 from the entrance slit 5 are
Due to the voltage V _D applied in between, only charged particles having a certain energy are focused on the exit slit, and the charged particles that have passed through the exit slit are detected by the detector. When obtaining the emission angle distribution of the charged particles, such measurement must be performed for the emission angles of the charged particle in the entire measurement angle range. In addition, in the measurement data thus obtained, the angle distribution cannot be analyzed unless data processing is performed after measurement.

C. DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention is a simple device that does not require an analyzer moving device,
The purpose is to enable simultaneous measurement of an energy spectrum image of a charged particle and an emission angle distribution image of a particle having an arbitrarily designated energy.

D. Means for Solving Problems As shown in FIG. 1, two hemispherical electrodes with different radii 1,
In a charged particle energy analyzer in which 2 are concentrically arranged with their cuts facing the same side, on the plane forming the cuts of both hemispheres, at an intermediate position between the edges of both hemispheres, between the two hemisphere electrodes, the surface A pair of incident angle regulating plates which are perpendicular to the radial direction and are spaced apart from each other and are parallel to each other, and the excitation point of the sample is located at an intermediate position of the base of the incident angle regulating plate, or the charge emitted from the sample is Position the image of the emission point by the particle, and on the cut surface between both hemispheres on the opposite side of this sample excitation point,
A plate having a vertically long slit 3 was installed in the radial direction, and a two-dimensional charged particle detecting means 4 was provided in a space on the opposite side of the slit from the both hemispherical electrodes.

E. Action Two hemispherical electrodes having different radii are arranged so that the cut ends face the same side in the same plane at the same spherical center. A voltage is applied between both electrodes. Among the charged particles emitted from the charged particle emission point on the sample between both electrodes, those having the same energy are
The hemispherical electrode is focused at a point on the cut surface opposite to the sample.
The position of this focusing point in the radial direction of the spherical surface is on the outer peripheral side as the particle energy is higher, and therefore a spectral image of energy can be formed in the radial direction as shown in FIG. This relationship holds for all surfaces passing through the point of particle emission on the sample and the center of the hemispherical electrode. The gist of the present invention is to regulate the directional distribution of the charged particles emitted between the two electrodes in a plane including the sample and the center of the hemispherical electrode, with respect to a plane direction perpendicular to a line passing through the center of the sample and the hemispherical electrode. Can be made incident between both electrodes in an angle range of approximately 180 degrees, so that the emission angle β in the plane F perpendicular to the line passing from the sample S to the sample and the hemispherical electrode center O as shown in FIG.
With respect to the charged particles emitted in step S1, on the surface G that includes the sample and the hemispherical electrode center between both electrodes and forms an angle β with the sample surface, a slit 3 that is vertically long in the radial direction and is provided on the side opposite to the sample S It forms the energy spectrum of the emitted particles. That is, the charged particles radiated from the sample surface in the direction of the emission angle β enter the exit slit at the same angle as the emission angle β and form an energy spectrum. Therefore, if the particles passing through the slit are detected in the plane G that includes the slit center line and forms β with the cut surface of the hemisphere, the energy spectrum of the particles emitted from the sample surface in the direction of the angle β can be measured. In this way, the two placed after the slit
A directional distribution image of each energy spectrum as shown in FIG. 3 is obtained on the dimensional detection surface. Here, the incident angle regulating plate has three functions. It has the function of reducing the aberration of the energy spectrum image of charged particles by narrowing the distance between the incident angle regulating plates, and the in-plane including the center of the sample and the hemispherical electrode due to the narrow distance between the incident angle regulating plates and the height of the partition wall. It has the function of controlling the emission angle of charged particles and the function of increasing the depth of focus of the spectral image (details will be described in the next section).

As described above, according to the present invention, it becomes possible to simultaneously perform two-dimensional measurement of the energy image of the charged particles and the emission angle distribution image.

F. Embodiment FIG. 1 shows an embodiment of the present invention. In FIG.
S is a sample, and 1 is an inner hemisphere electrode, and a + voltage is applied (in the case of electron energy analysis). 2 is the outer hemisphere electrode
Voltage is being applied. The inner hemisphere electrode 1 and the outer hemisphere electrode 2 are concentrically arranged on the same side. Reference numeral 3 denotes a slit, which is a high and low anti-conductor and is formed vertically in a radial direction on a plate whose both ends are connected to both electrodes. The slit 3 may be omitted. A two-dimensional charged particle detector 4 is a fluorescent plate or the like for two-dimensionally detecting charged particles incident on the slit 3. The two-dimensional detector 4 detects charged particles forming an energy spectrum image in the radial direction and an emission angle distribution image in the direction perpendicular to the radius as shown in FIG. Reference numeral 5 denotes a visual field regulating plate for limiting the emission angle of the charged particles in the plane of the paper of FIG. 1 and in the plane rotated about the line connecting the center of the sample and the center of the sphere. Reference numeral h denotes an excitation ray incident hole provided in the electrode 2, and the excitation ray is incident between the pair of incident angle regulating plates 5 so as to irradiate one point on the surface of the sample S. Here, since the detector 4 is away from the slit 3, unless the depth of focus of the energy spectrum image on the slit 3 is deep, the resolution of the energy spectrum decreases. Therefore, the incident angle regulating plate 5 deepens the depth of focus of the energy spectrum image to prevent the resolution from decreasing. Considering a plane perpendicular to the sample plane, that is, a plane of β = 90 ° as the plane G, when the regulating plate 5 is not provided, the energy spectrum image on the plane G is a particle other than the particles emitted in the vertical direction from the sample plane. Will also be included, and the resolution of the directional distribution will deteriorate. This is a problem that occurs in other directions as well, so that the incident angle regulating plate 5 is required. Reference numeral 6 is a guard ring provided along the cut surfaces of both hemispherical electrodes 1 and 2 for maintaining an electric field distribution. Reference numerals 7 and 8 are acceleration grids for illuminating the fluorescent plate of the detector 4, the first grid 7 is a semi-cylindrical shape with the slit 3 as an axis, and the second grid 8 is applied with a + voltage. By using high and low anti-conductors for the slits 3 and the grid 7, it is possible to prevent the potential change due to the charged particles colliding with each other, and to generate the same potential as the radial potential distribution inside both electrodes at each position. ing.

The positions of the incident angle regulating plate 5 and the excitation point of the sample S are set to both electrodes 1, 2
It can be anywhere in the middle of, but the closer to the outside, the clearer the image. Further, the measurement itself is possible without the slit 3.

In the above embodiment, a plane detector is used as the two-dimensional detector 4, but as shown in FIG. 4, the line sensor 10 parallel to the slit 3 is rotated about the line passing through the spherical center and the slit 3. When the emission angle distribution image is measured by the above method, the angle and the image interval coincide with each other, the distortion of the angle scale that occurs when the direction distribution image is projected on a plane is eliminated, and the emission angle distribution image that is easier to see can be obtained.

G. Effect According to the present invention, it becomes possible to simultaneously measure the energy distribution of charged particles and the distribution of emission angles with a simple device, and simultaneously detect emitted particles in multiple directions. The same S / N ratio can be measured, the measurement efficiency is improved, and the cost of the device can be reduced because there is no need to move the energy analyzer.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a perspective view of the above embodiment, FIG. 3 is a sectional view for explaining emission angle distribution measurement, and FIG. 4 is a front view of a modified embodiment. FIG. 5 is a sectional view of a conventional example. S …… Sample, 1 …… inner hemisphere electrode, 2 …… outer hemisphere electrode, 3 …… slit, 4 …… two-dimensional detector, 5 …… incident angle control plate, 6 …… guard ring, 7 …… first 1 grid, 8 …… 2nd grid.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-214347 (JP, A) SAIKAI Shou-49-141188 (JP, U)

Claims (1)

[Claims] 1. An apparatus for irradiating a sample with an excitation ray and analyzing the sample by charged particles emitted from a reflection area of the sample, wherein two hemispherical electrodes having different radii are concentrically arranged with their cut ends facing the same side. Then, on the plane that forms the cuts of both hemispheres, at the intermediate position of the edges of both hemispheres, a pair of incident angles parallel to each other with the surfaces perpendicular to the radial direction and slightly spaced apart toward each other between the hemisphere electrodes. A regulation plate is provided, and the excitation point of the sample is located at the intermediate position of the base of the incidence angle regulation plate, on the opposite side to the sample excitation point of the cut surfaces of both hemispheres, and the both hemisphere electrodes with respect to the cut surface. A charged particle analyzer characterized in that a two-dimensional charged particle detecting means is provided apart from the cut surface in a space on the opposite side.