JP2001266786A - Analysis method using electron spectroscope with angle resolving incident lens system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large-aperture angle resolving electron spectroscope for achieving electron spectral measurement, having high angular resolution which is applicable for wide-range measurement without depending on an acquiring region. SOLUTION: The angle resolving electron spectroscope makes the electrons emitted from the surface of a sample to be injected into a static electronic lens, via an introducing port. The diffraction plane of the static lens is provided with an angle-limiting aperture, which electrons converged by the electron lens are introduced via an aperture passage port to an electron analyzer for analyzing electron energy to be analyzed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-diameter angle-resolved electron spectrometer applicable to an electron spectrometer and a method for analyzing electrons using the electron spectrometer, and more particularly to an X-ray photoelectron spectrometer and an Auger. The present invention relates to a large-diameter angle-resolved electron spectrometer applicable to an electron spectroscope such as an electron spectrometer and a photoelectron diffraction device, and a method of analyzing electrons using the electron spectrometer.

[0002]

2. Description of the Related Art Electron spectrometers such as an X-ray photoelectron spectrometer, an Auger electron spectrometer, and a photoelectron diffractometer are known as analyzers for solid surfaces. Used in the material industry.

[0003] In these electron spectrometers, an apparatus using angle-resolved electron spectrometry realizes angle-resolved measurement by photoelectron / Auger electron spectroscopy (XPS, AES) measurement or similar measurement using ions. . This electron spectroscopy device utilizes the technology of the field of electro-optics from the viewpoint of using not only the surface analysis technology but also the technology of the spectroscopic analysis technology, and from the viewpoint of limiting the angle of electrons to an electro-optical or geometric angle. It is known as a device that can be realized by using it.

[0004] Angle-resolved electron spectroscopy applied to a conventional electron spectrometer mainly includes the following two methods.
Each of these two measurement methods uses a combination of a hemispherical analyzer and an incident lens.

In the first method, as shown in FIG. 1, when an electron emitted from one point on the sample surface 1 enters the analyzer, the electron at a solid angle that takes in the electron from the incident lens 3 is taken into consideration. The angle is limited. In the first method, the incident lens 3 has a function of converging electrons emitted from the sample 1 to the entrance of the analyzer, and has an angular resolution of a capturing area Sa on the sample 1 and a lens converging surface (capturing area Sa). Is equivalent to the image plane of the object point plane), and is geometrically determined by the size of the aperture 4 provided at the entrance of the analyzer and the position of the virtual lens 3.

That is, in the electrostatic lens optical system shown in FIG. 1, the capture area Sa of the sample 1 corresponds to an object point, and the aperture of the aperture 4 is located at an image point position where an image of the object point is formed. ing. Therefore, the electrons from the region Sa are guided to the analyzer.

In the second method, as shown in FIG. 2, the angle of the electrons is limited by a slit or an aperture 6. That is, the slit or the aperture 6 defines a parallel passage of electrons, and only the electrons passing through this passage are introduced into the analyzer. In this method, the angular resolution is determined geometrically by the shape of the aperture. Further, in the second method, unlike the first method, it is possible to measure with a high angular resolution even in a wide measurement area.

[0008]

The above-described first method is widely applied to an electron spectrometer using a hemispherical analyzer. However, there is a problem that the angular resolution depends on the size of the capturing area Sa, and when a large area is measured instead of a minute area, it is impossible to detect with a high angular resolution. There is.

In the above-mentioned second method, there is a problem that as the angle restriction on electrons becomes stricter, the loss increases, the detection sensitivity deteriorates, and the detection intensity decreases. These problems result in a problem that the measurement requires a long time and the reliability of the measurement result is reduced. Further, in the second method, when changing the angular resolution, there is a problem in that the aperture has to be exchanged, and the like is troublesome.

In the field of semiconductor technology in recent years, surface development by electron spectroscopy is indispensable for development, evaluation and analysis of various materials. Among them, angle-resolved measurement is of great importance, such as depth analysis and structural analysis using photoelectron diffraction measurement. However, due to the above-mentioned problems, the current analysis request has not been sufficiently satisfied. In recent years, there has been a demand for the development of an electron spectrometer capable of analyzing electrons with higher angular resolution that solves the above-mentioned problem.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object that the angular resolution does not depend on the capturing area and is higher than that in which a wide area can be measured. An object of the present invention is to provide a large-diameter angle-resolved electron spectrometer capable of realizing electron spectrometry with angular resolution and an analysis method using the electron spectrometer.

Further, the present invention provides a large-diameter angle-resolved electron spectrometer capable of realizing electron spectrometry with high angular resolution and high sensitivity without using an angle-limited aperture, and an analysis using the electron spectrometer. There is a way to provide.

Further, according to the present invention, there is provided a large-diameter angle-resolved electron spectrometer capable of realizing electron spectrometry capable of controlling the angular resolution only by changing the electrode potential, and an analysis method using the electron spectrometer. To offer.

According to the present invention, capturing means for allowing capture of electrons emitted from the sample surface, electron lens forming means for forming an electrostatic electron lens for condensing the captured electrons, and the condensing lens An aperture placed on the diffraction surface of the device, which has a passage opening that allows the passage of condensed electrons, and an aperture that limits the angle of the incident electrons, and analyzes the energy of the electrons that have passed through this aperture And an electron analyzer for performing the method.

Further, according to the present invention, a capturing step of capturing electrons emitted from the sample surface, a focusing step of focusing the captured incident electrons with an electrostatic electron lens, and a focusing step of the focusing lens An angle limiting step of directing the condensed electrons toward the electron passage of the aperture arranged on the diffraction surface and allowing the collected electrons to pass through the passage, and limiting the angle of the incident electrons, and analyzing the energy of the electrons passing through the aperture. And an analysis step using an angle-resolved electron spectrometer.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a large-diameter angle-resolved electron spectrometer according to the present invention will be described below with reference to the drawings.

FIG. 3 schematically shows a large-diameter angle-resolved electron spectrometer according to an embodiment of the present invention. In FIG. 3, 10 is a solid sample whose surface is to be measured by this system. The sample 10 is irradiated with X-rays from an X-ray source (not shown), and photoelectrons are emitted from the sample surface by the external photoelectric effect by the X-ray irradiation. In measurement using photoelectron spectroscopy, photoelectrons are emitted from a sample by X-rays of a constant energy, and the kinetic energy of the photoelectrons is accurately measured by an electron spectrometer, that is, an electron analyzer. Binding energy (binding energy) is required.

The apparatus shown in FIG. 3 comprises an energy analyzer 14 as an analyzer for analyzing the energy of photoelectrons, and an angle-resolving incident lens system 12 attached to the entrance side of the energy analyzer 14.

The angle-resolving incident lens system 12 includes an electron capturing port 16 for capturing emitted photoelectrons, an electrode section 20 for forming an electrostatic lens 18 for converging the captured electrons to the analyzer entrance, and an electrode section 20 for forming the electrostatic lens 18. A diffraction surface aperture 22 for limiting the incident angle of photoelectrons guided to the energy analyzer 14 is provided. Also,
The energy analyzer 14 includes an electron analyzer 24 formed in a hemispherical shape and applied with a high voltage to generate an electric field therein, and a detector 26 for detecting photoelectrons. The detector 26 is connected to a position computer for calculating the incident position, and employs a so-called position-sensitive detector that detects the incident position and energy of photoelectrons and outputs data as a detection signal.

Although not shown, the angle-resolving incident lens system 12 and the energy analyzer 14 are arranged in a magnetic shield, and these, including the sample 10, are arranged in an evacuated housing. Further, the electron spectrometer controls a rotation mechanism 30 including a stepping motor for rotating the sample 10 to be measured, an X-ray source to generate X-rays having a desired wavelength, and supplies a voltage to be applied to the analyzer 24. A measurement control unit (not shown but usually used by a personal computer, which controls according to the sample and processes the data related to the high voltage applied to the analyzer 24 and the detection data from the detector 26 to analyze the sample. ).

FIG. 4 schematically shows details of the optical system of the angle-resolving incidence lens system 12 shown in FIG. As shown in FIG. 4, the electrons emitted from the sample 10 pass through the inlet 16 and enter the lens electrode 2.
Pointed to zero. At this time, the measurement area on the sample 10 is determined by the size of the inlet 16. Lens electrode part 1
The electrostatic lens 18 formed in 6 has a function of converging electrons that have entered in parallel to the diffraction surface of the electrostatic lens 18, that is, the diffraction surface aperture 22 disposed on the back focal plane. More specifically, when the sample 10 is irradiated with X-rays, electrons are emitted from the sample 10 in various directions according to the composition and structure of the sample 10,
Although directed to the electrostatic lens 18, the diffractive surface aperture 22
Is located on the diffraction plane, that is, the back focal plane,
Only electrons incident on the electrostatic lens 18 in parallel with the optical axis of the electrostatic lens 18 are converged on the aperture of the diffraction surface aperture 22 that allows the passage of electrons, and pass through the diffraction surface aperture 22 into the analyzer 24. Be guided. In other words, the angle pattern of the emitted electrons is formed on the diffraction surface, and the plane aperture 22 is arranged on the diffraction surface.
Electrons emitted from the sample 10 and having a certain polar angle and azimuth angle are collected, and only electrons directed in a predetermined direction can be selectively captured. The electrons that have passed through the diffraction plane aperture are energy analyzed by the energy analyzer 14. That is, only specific electrons of the electrons introduced into the analyzer 24 are incident on the detector 26 through the analyzer path on the circular arc due to the electric field formed in the analyzer 24. The position and intensity of the light incident on the detector 26 are input to the measurement control unit as data and analyzed, and the measurement control unit analyzes the structure, composition, and the like of the sample surface.

As described above, the angle-resolved electron spectroscope is constituted by the intake port 16, the electrostatic lens 18 formed by the converging lens electrode 20, the diffraction surface aperture 22, and the electron analyzer 24. At this time, the angular resolution depends on the magnitude of the angular dispersion of the diffraction pattern formed by the lens action of the electrostatic lens 18 and the diffraction plane aperture 22.
Is determined by the size of

A description will be given of the angle resolving incidence lens system 12 according to one embodiment of the present invention by comparing the prior art with attention to the following effects.

(1) According to the decomposition type electron spectrometer of the present invention, it is possible to realize electron spectrometry having a high angular resolution in which the angular resolution does not depend on the capturing area and a wide area can be measured.

A description will be given by comparing the obtained angular resolution between the conventional lens system using the image plane aperture shown in FIG. 1 and the lens system shown in FIG.
In the conventional lens system using the image plane aperture of FIG. 1, the angular resolution is determined by the size of the measurement area, the lens length (position), and the size of the image plane aperture. As shown in FIG. 5, when the size of the measurement area is a circle of radius r, the size of the image plane aperture is a circle of radius R, and the lens length is D,
The angular resolution is

[0026]

(Equation 1)

Is defined as Therefore, in order to restrict the angle strictly, the lens length D may be increased, or the size R of the image plane aperture may be reduced. However, as the measurement area r increases, the angular resolution decreases accordingly. In contrast, in a lens system using a diffraction surface aperture as shown in FIG. 4,
The angular resolution is determined only by the size of the diffraction plane aperture. That is, the angular resolution does not depend on the size of the measurement area, and can be improved by reducing the diameter of the diffraction surface aperture.

(2) According to the decomposition type electron spectrometer of the present invention, electron spectrometry with high angular resolution and high sensitivity without using an angle limiting aperture can be realized.

In the conventional lens system using the angle limiting aperture shown in FIG. 2, the angular resolution is determined only by the shape of the aperture. That is, as shown in FIG. 6, when the size of the measurement area is a circle with a radius r, the work distance is D, the length of the aperture is d, and the length of the aperture opening is a, the angular resolution is:

[0030]

(Equation 2)

Is defined as Therefore, in order to tighten the angle limit, the length d of the aperture may be increased and the length a of the aperture opening may be reduced. The size of the measurement area does not affect the angular resolution. However, as the length a of the aperture opening decreases, the aperture (transmittance) decreases accordingly, and the detection intensity decreases. On the other hand, in a lens system using a diffraction surface aperture as shown in FIG. 4, on the other hand, the angular resolution is determined only by the size of the diffraction surface aperture, and therefore does not depend on the size of the intake. The opening (transmission) rate is 100%.

(3) According to the disassembled electron spectrometer of the present invention, it is possible to realize electron spectrometry in which the angular resolution can be controlled only by changing the electrode potential.

In a lens system using a diffraction surface aperture as shown in FIG. 4, the angular resolution can be controlled only by changing the potential relationship of the lens electrode section 20 and changing the optical conditions. Even in a lens system using a conventional image plane aperture, it is possible to control the angular resolution in the same manner according to optical conditions. However, the angular resolution changes with the size of the measurement area, and it is impossible to control only the angular resolution. Further, in a conventional lens system using an angle limiting aperture, since it is determined geometrically irrespective of optical conditions, in order to change the angular resolution, it is necessary to exchange the angle limiting aperture. That is, the lens system using the diffraction plane aperture can easily control the angular resolution only by the optical conditions without affecting other measurement parameters.

As described above, the decomposition type electron spectrometer of the present invention has the following features.

Electrons (or ions) entering the entrance lens system from the inlet are condensed by an (electrostatic) converging lens, and the angle of the incident electrons is limited by an aperture arranged at the diffraction surface. You. The electrons that pass through the aperture and are angle-limited are analyzed for energy by an electron analyzer, and angle-resolved electron spectroscopy is realized.

Further, the decomposition type electron spectroscope of the present invention comprises an angle-limited type lens system and an electron analyzer. In particular, the angle limiting lens system consists of an electron inlet, a (electrostatic) convergent lens and a diffractive surface aperture.

The functions of the converging lens and the diffraction surface aperture are to converge electrons to the aperture position by a lens function to form a diffraction surface, and to limit the angle by arranging the aperture on the diffraction surface.
The role of an electron analyzer is to examine the energy state of electrons by performing energy analysis on angle-limited electrons. The angular resolution can be controlled by changing the optical conditions and the size of the diffractive surface aperture.

[0038]

As described above, according to the large-diameter angle-resolved electron spectrometer and the analysis method using the electron spectrometer of the present invention, the angular resolution does not depend on the capturing area, and a wide area can be measured. Electron spectrometry can be realized with a high angular resolution.

According to the large-diameter angle-resolved electron spectrometer and the analysis method using the electron spectrometer of the present invention, electron spectroscopy with high angular resolution and high sensitivity can be performed without using an angle limiting aperture. Measurement can be realized, and the angular resolution can be controlled only by changing the electrode potential.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the structure of an electron lens optical system arranged on the electron incident side of a hemispherical analyzer in a conventional electron spectrometer using angle-resolved electron spectrometry.

FIG. 2 is a schematic diagram showing the structure of an electron lens optical system arranged on the electron incident side of a hemispherical analyzer in a conventional electron spectrometer using angle-resolved electron spectrometry.

FIG. 3 is an explanatory view schematically showing a large-diameter angle-resolved electron spectrometer according to one embodiment of the present invention.

FIG. 4 is a schematic diagram showing details of an optical system of the angle resolving incident lens system shown in FIG. 3;

FIG. 5 is a schematic diagram for explaining an angular resolution derived from a measurement area and a size of an image plane aperture in the optical system of the incident lens system shown in FIG. 1;

6 is a schematic diagram for explaining an angular resolution derived from a measurement area and an aperture dimension in the optical system of the incident lens system shown in FIG. 2;

[Explanation of symbols]

 Reference Signs List 1,10: sample 3: incident lens 4, 6: aperture 12: incident lens system for angle resolution 14: energy analyzer 16: electron inlet 18: electrostatic Lens 20: Electrode section 22: Diffraction surface aperture 24: Electronic analyzer 26: Detector

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideshi Ishii 3-39-16 Hikawadai, Nerima-ku, Tokyo 205 Saito 205 (72) Inventor Shinji Omori 1-2-5, Monzennakacho, Koto-ku, Tokyo Yamaguchi Building 302 (72) Inventor Masaru Shiraki 1-27-26 Higashiyama, Meguro-ku, Tokyo Chalet Higashiyama 102 F term (reference) 5C038 FF01 FF07 KK06

Claims (4)

[Claims] An electron lens forming means for forming an electrostatic electron lens for condensing the electrons; and a diffractive surface of the condensing lens. An aperture that is arranged and has a passage port that allows the passage of condensed electrons, an aperture that limits the angle of the incident electrons, and an electron for analyzing the energy of the electrons that have passed through the aperture An angle-resolved electron spectrometer, comprising: an analyzer. 2. The apparatus according to claim 1, further comprising: an X-ray source for irradiating the sample surface with X-rays to emit electrons from the sample surface; and a rotating mechanism for rotating the sample. Angle-resolved electron spectrometer. 3. A capturing step for capturing electrons emitted from the sample surface, a focusing step of focusing the captured incident electrons by an electrostatic electron lens, and An angle limiting step of directing the condensed electrons toward an electron passage of the aperture and allowing the collected electrons to pass therethrough, and limiting an angle of the incident electrons; and an analysis step of analyzing the energy of the electrons passing through the aperture. A method for analyzing electrons using an angle-resolved electron spectrometer. 4. An X-ray irradiating step of irradiating the sample surface with X-rays to emit electrons from the sample surface, and a rotating step of rotating the sample while the X-rays are being irradiated. 4. A method for analyzing electrons using an angle-resolved electron spectrometer according to claim 3, wherein: