JPH0668474B2 - Photoelectron analyzer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoelectron analyzer that analyzes the elemental state of a sample surface by energy spectroscopy of photoelectrons emitted from the sample surface irradiated with X-rays. It is a thing.

(Prior art and its problems) A conventional photoelectron analyzer is an X-ray source and a hemispherical analyzer (He-mispherical Ana- lyzer) having an irradiation area of several mmφ to 10 mmφ.
Most of them are used in combination. This hemispherical spectroscope has the feature that it can disperse electrons emitted from a wide area with high energy resolution, and detects almost all photoelectrons emitted from an irradiation area of several mmφ to 10 mmφ. Very sensitive analysis can be performed. In the following, this is the first
Called the conventional example of. However, the first conventional example has a drawback that only average information can be obtained when the sample surface number is from mmφ to 10 mmφ.

Next, an improved X-ray source with the same X-ray source was used, and a two-stage cylindrical mirror spectroscope (Double
There is a second conventional example using -pass Cylindrical Mirror Analyzer). This two-stage cylindrical mirror spectroscope disperses only the electrons emitted from a narrow area, and the electrons emitted from other areas can be interrupted on the way, so for example, only the area of about 2 mmφ on the sample surface It has the advantage of being able to obtain information on However,
The two-stage cylindrical mirror spectroscope has a complicated structure and is very large, and since there are four or more meshes that transmit electrons, the transmittance is greatly reduced, so compared to the first conventional example. 1/10
There is a drawback that only a certain degree of sensitivity can be obtained. In addition, there is a drawback that analysis cannot be performed at all in a narrower area of 2 mmφ or less.

Next, as an apparatus for improving the above, a micro focus electron gun and an imaging dispersive crystal are used as in the X-ray source section of the embodiment described later to reduce the X-ray irradiation area itself. There is a third conventional example in which the hemispherical spectroscope of (3) is combined. However, in the third conventional example, the analysis area can be reduced to about 0.1 to 0.2 mmφ, but the sensitivity is reduced by the amount of the reduced analysis area, which is 1/10 of that of the first conventional example.
Only a sensitivity of about 0 was obtained, making it very difficult to carry out practical analysis. Therefore, the analysis area is 1 mmφ
Expanding to the above, or adding a conventional X-ray source with a wide irradiation area, a practical analysis is
After all, the method of doing it in a large area is adopted.

As described above, in the conventional case, all of the first, second, and third conventional examples can perform analysis in a wide area with high sensitivity.
In a narrow region of 1 mmφ or less, there is a drawback that practical photoelectron analysis cannot be performed due to lack of sensitivity. Moreover, it is completely impossible to obtain a photoelectron image showing the state distribution of elements in the lateral direction on the sample surface.

(Object of the Invention) The object of the present invention is to solve the above problems, to perform photoelectron analysis in a narrow region of 1 mmφ or less at a practically high sensitivity, and also to obtain a photoelectron image of a lateral element distribution. It is to provide a photoelectron analysis device capable of performing the above.

(Structure of the Invention) The present invention relates to a photoelectron analyzer including an X-ray source and an electron spectroscope, which is an ultra-fine focus type electron gun in which the X-ray source is made into a bundle of about 0.1 mm in diameter. A target irradiated with an electron beam is used, and X-rays emitted from the target are focused on a sample surface by using an imaging type dispersive crystal plate, and the electron spectroscope is a single-stage cylindrical mirror spectroscope (Single- The above-mentioned object is achieved by a photoelectron analyzer using a pass Cylindrical Mirror Analyzer).

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which 10 is a vacuum chamber, 1 is an electron gun, 11 is an electron beam deflection plate, 12 is a deflection / scanning power source,
13 is an electron beam, 14 is an electron beam irradiation position, 15 is an electron gun differential evacuation chamber, 2 is a movable target, 3 is an imaging spectroscopic crystal plate, 31 is a Roland circle, 32 is an X-ray, 4 is a sample, 41 is X
Line irradiation position, 5 single-stage cylindrical mirror type spectroscope, 51 position-resolving detector, 52 spectroscopic sweep power supply, 53 photoelectron, 6 recorder, 61 recorded photoelectron spectrum, 7 CRT, 71
Is a photoelectron image.

The electron gun 1 is a micro focus type electron gun in which the irradiation area of the electron beam 13 is about 0.1 mmφ, and its irradiation position is determined by the deflection plate 11.
A deflection function that can arbitrarily change 14 is added. When the target 2 is irradiated with the electron beam 13, X-rays 32 are generated from an area having a size equal to the irradiation area, that is, a small area of about 0.1 mmφ. The image-forming type dispersive crystal plate 3 serves to disperse X-rays, that is, to perform monochromatization and to collect X-rays (that is, to form an image of an X-ray source), and is usually called a Johansson type. . In this case, a dispersive crystal plate 3 having an imaging magnification of 1 is used, so that an X-ray image in 0.1 mmφ is formed on the imaging plane. That is, by locating the sample surface 4 on the Roland circle 31 of the image formation, it is possible to irradiate the position on the sample 41 with X-rays of 0.1 mmφ in a fine bundle. The X-ray irradiation position 41 moves corresponding to a slight movement of the X-ray generation position, that is, the electron beam irradiation position 14 (dotted lines in the figure indicate the electron beam and the X-ray when moved). . Therefore, by applying a deflection voltage to the deflection plate 11, the X-ray irradiation position 41 on the sample 4 can be arbitrarily changed.

In the target 2, the irradiation of the electron beam is concentrated only on the area of about 0.1 mmφ, so that the temperature of this area rises and the damage easily occurs. Therefore, the target 2 is mechanically moved at high speed in a two-dimensional direction so that the time-averaged irradiation area on the surface of the target 2 is increased. If the moving distance in the two-dimensional direction is set to 1 mm x 1 mm, the time-averaged irradiation area will be 100 times larger, and damage to the target can be greatly reduced. Further, the X-ray intensity can be increased by that amount, and the X-ray intensity can be 10 times or more compared with the third conventional example. That is, in the case of the ultrafine focus type electron gun 1 in which the electron beam irradiation region is very narrow as in this embodiment, the two-dimensional movement of the target 2 is very effective. This two-dimensional movement is, for example, the rotational movement 20 of the target 2.
It is realized by a combination of 1 and axial reciprocating motion 202.

Next, in this embodiment, the one-stage cylindrical mirror spectroscope 5 is used as the spectroscope, but the one-stage cylindrical mirror spectroscope 5 has a simple structure and a small size as well known. Regardless, it has a very high transmittance, that is, electron collection and detection efficiency. The transmittance is represented by the ratio of the detected amount of certain energy emitted from the sample surface to the total amount of electrons. The value is about 0.01 for the hemispherical spectroscope, while it is about 0.1 for the one-stage cylindrical mirror spectroscope. The value of is about 10 times higher.
On the other hand, however, the one-stage cylindrical mirror spectroscope 5 has a very small area on the sample where normal spectroscopic analysis is possible, and is only about 1 mmφ. Further, if there are electrons emitted from other than this region, they have a property of adversely affecting the energy resolution. The single-stage cylindrical mirror spectroscope 5 has never been used before in a photoelectron analyzer, but it is envisioned that it is a characteristic unsuitable for such a photoelectron analyzer. However, when used as in this example, since the X-rays are radiated onto the sample 4 with a fine bundle of about 0.1 mmφ, there is no adverse effect on the energy resolution, and the size and cost are low. Therefore, all the advantages such as being able to perform analysis with a sensitivity that is about 10 times higher than that of the conventional hemispherical spectroscope will be utilized.

Next, the position-resolved detector provided along with the one-stage cylindrical mirror type spectroscope 5 of the present embodiment is originally a detector that can know where electrons have arrived on the detector surface. , It is possible to change the energy resolution and detect electrons with different energy values at the same time.
The reason for installing this is as follows. That is, since the transmission energy of the one-stage cylindrical mirror type spectroscope 5 changes during the energy sweep, the energy resolution also changes at the same time. Therefore, this position-resolved detector 51 is combined and the energy resolution of the detector is changed in synchronization with the energy sweep so that energy spectroscopy can be finally performed with a constant energy resolution. Due to this arrangement, in the apparatus of this embodiment, the single-stage cylindrical mirror spectroscope 5 is used.
While using, it is possible to strictly satisfy the necessary conditions of photoelectron spectroscopy as in the conventional example.

According to the apparatus of the present embodiment having the above-described structure, the sensitivity of the X-ray is reduced by about 1/100, and the 1-stage cylindrical mirror type spectroscope with the movable target and the position-resolving detector is used. It is possible to compensate by increasing the sensitivity by using the instrument, and to perform photoelectron analysis in an extremely narrow area of 0.1 mmφ with high sensitivity and energy resolution almost similar to those of the first conventional example.

Therefore, when the deflection voltage of the electron beam is fixed and the sweep signal from the spectral sweep power supply and the photoelectron signal from the detector are synchronized, the photoelectron spectrum of a certain specific area of about 0.1 mmφ is narrowed on the recorder 6. The analysis result will be displayed.

Next, the sweep of the spectrum is fixed, and the scanning and scanning signals applied from the deflection / scanning power source 12 of the electron beam 13 to the deflecting plate 11 are used to scan vertically and horizontally, and the photoelectron detection signal from the detector 51 is used as the luminance modulation signal. When adding as, add 1m on sample 4 on CRT7
An image of a specific photoelectron with an area of about m openings (meaning 1 mm square) will be displayed with a spatial resolution of about 10 × 10 divisions. According to this analysis method, an image corresponding to each elemental state on the surface of the sample 4 is obtained, and the lateral distribution of the elemental state is very clearly shown. In addition, since the electron beam is constantly deflected and scanned in this method, it is possible to obtain the same energy dispersion effect as moving the target frequently in the two-dimensional direction. It is possible to obtain strong X-rays.

In this embodiment, the electron gun 1 has an electron gun differential exhaust chamber 15
The electron beam 13 is extracted from the aperture 150 to the outside. Since this electron beam 13 is very finely bundled, this aperture 15
The 0 can also be of a very small aperture.
The electron gun differential evacuation chamber 15 is differentially evacuated by another high vacuum pump different from the ultra high vacuum pump that discards the target 2. Since the electron gun 1 becomes extremely hot, the amount of gas released is extremely large. However, when the differential exhaust structure is adopted as in the present embodiment, the aperture of the aperture 150 for sending out the electron beam 13 is very small, and therefore the gas is emitted. The generated gas hardly flows toward the target and is exhausted in the direction of arrow 151 by the high vacuum pump. Therefore, the target is always kept in ultra-high vacuum and there is almost no adverse effect of contamination.

(Effects of the Invention) As described above, according to the present invention, it is possible to practically perform photoelectron analysis in a narrow region of 1 mmφ or less, and the analysis target is not limited to the conventional uniform material. Therefore, it is effective to provide a photoelectron analysis device that can be applied to general materials and parts for photoelectron analysis.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. In the figure, 10 is a vacuum chamber, 1 is an electron gun, 11 is an electron gun deflection plate, 12 is a deflection scanning power supply, 13 is an electron beam, 14 is an electron beam irradiation position, 2 is a movable target, and 15 is an electron gun difference. Dynamic exhaust chamber, 3 is an image-forming spectroscopic crystal plate, 31 is a Roland circle, 32 is X-ray, 4 is a sample, 41
Is an X-ray irradiation position, 5 is a single-stage cylindrical mirror type spectroscope, 51 is a position resolution type detector, 52 is a spectral sweep power supply, 53 is a photoelectron, 6 is a recorder, 61 is a photoelectron spectrum, 7 is a CRT, 71 is a It is a photoelectron image.

Claims (5)

[Claims] 1. A photoelectron analyzer comprising an X-ray source and an electron spectroscope, wherein the X-ray source is irradiated with an electron beam of a micro focus electron gun which is made into a bundle of about 0.1 mm in diameter. Characterized in that an X-ray emitted from the target is focused on a sample surface by using an imaging type dispersive crystal plate, and a one-stage cylindrical mirror type spectroscope is used as the electron spectroscope. Photoelectron analyzer. 2. The photoelectron analyzer according to claim 1, wherein the target is movable at least in a two-dimensional direction perpendicular to the electron beam. 3. The photoelectron analyzer according to claim 1, wherein the micro-focus electron gun having an electron beam deflecting function is used, and the electron beam irradiation position of the target is moved. An optoelectronic analyzer characterized by: 4. The photoelectron analyzer according to claim 1, wherein the one-stage cylindrical mirror spectroscope having a position-dispersive detector is used, and it corresponds to the energy sweep of the spectroscope. A photoelectron analysis device, characterized in that the energy resolution of the detector is changed. 5. The photoelectron analyzer according to claim 1, further comprising means for differentially exhausting the electron gun.
An optoelectronic analyzer characterized in that the electron beam is sent out from an aperture of the differential exhaust chamber, and means for differentially exhausting the differential exhaust chamber is provided.