JPH0499952A - Method and apparatus for analyzing surface - Google Patents

Abstract

PURPOSE:To accurately analyze a minute region by condensing the light of a vacuum ultraviolet region in soft X-rays to scan the surface of a sample and using the obtained surface image of the sample to set and grasp an analytical point or region. CONSTITUTION:The surface of a sample 3 is irradiated with light to observe the particles discharged from the surface of the sample 3. Further, the surface of the sample 3 is scanned by condensed beam to obtain the signal corresponding to the position of the condensed beam on the surface of the sample 3. Scanning is carried out by controlling the minute movement of the sample, an optical element or a light source by a controller 10. The surface image of the sample is obtained on the basis of the signal corresponding to the minute movement and the observation signal of the discharged particles and an analytical region is set based on said image. By this method, accurate analysis can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface analysis technique for a microscopic area, and particularly to a method and an apparatus for improving the ability of surface analysis to easily set and understand an analysis area.

[Conventional technology]

In recent years, surface analysis techniques for microscopic areas have become important.

For example, in the analysis and identification of residual contaminants on the surface of a semiconductor circuit element, a micro area with a diameter of several μm to 0.1 μm is the target of analysis. Furthermore, in the analysis of chemical reactions such as thin film formation and catalytic reactions on the surface, the area below 1 μm μm is the target of analysis.

In response to these demands, a method has been proposed in which X-rays are focused on a minute area on the sample surface and fluorescent X-rays emitted from the sample surface are observed (for example, Japanese Patent Laid-Open No. 62-265555 , Japanese Unexamined Patent Publication No. 61-88200).

[Problem to be solved by the invention]

In the above-described conventional technology, no consideration is given to clarifying which region on the sample surface is being analyzed. When the size of the analysis area is on the μm order or smaller, reliable surface analysis is difficult unless there is an appropriate means for setting and understanding the analysis area.

An object of the present invention is to provide a method and apparatus for surface analysis of a minute area that allows easy setting and understanding of the analysis area.

[Means to solve the problem]

In order to achieve the above objective, light is focused on the sample surface and particles (electrons, photons, ions, neutral particles, etc.) released from the sample surface due to the light irradiation are observed. Furthermore, the sample surface is scanned by the condensing beam 11 to obtain an image (image) of the sample surface based on the signal corresponding to the position of the condensed beam on the sample surface and the observation signal of the particles. . The analysis area is set and understood on this video.

The light irradiated onto the sample surface ranges from soft X-rays to vacuum ultraviolet light, and is monochromatic. This light is focused onto the sample surface using a reflective optical element.

Scanning of the focused beam on the sample surface is performed by minute movement of the sample, minute movement of the optical element (including minute angle change), minute movement of the light source, or the like. The above-mentioned minute movement is controlled by controller 1 to roller. Minute diameter from this controller! An image of the sample surface is obtained based on the signal corresponding to the amount of Il (or minute angle change) and the observation signal of the emitted particles described above. Based on this video, the analysis area is set.

[Effect]

Electrons, photons, ions, neutral particles, etc. are emitted from the sample surface irradiated with light in the vacuum ultraviolet region from soft X-rays. By analyzing the types and energies of these particles, it is possible to identify the element types and chemical bonding states within the irradiated area. In particular, electron spectroscopy, which analyzes the energy of emitted electrons, is ideal for identifying chemical bond states.

In order to focus light in the vacuum ultraviolet region from soft X-rays to an area with a diameter of several μm or less, an ultra-low aberration optical element is required. As such an optical element, a composite aspherical reflecting mirror such as a Walter type reflecting mirror or a Kirkpahrrick-Petz type reflecting mirror is most suitable.

Reflective optical elements have no chromatic aberration (differences in light collection characteristics for light of different wavelengths). In surface analysis, the wavelength of the light irradiated onto the sample surface is often changed in order to change the surface sensitivity. At this time, if a reflective optical element is used, the position and size of the analysis area basically do not change with respect to changes in the wavelength of the irradiation light.

This property is essential for micro-area analysis.

As mentioned above, by using a reflective optical element to focus light in the vacuum ultraviolet region from soft X-rays onto the sample surface and observing the type and energy of particles emitted from the sample surface, it is possible to detect microscopic regions. Surface analysis is possible.

Next, the means for grasping the setting 2 of the analysis area and its operation will be explained. In order to understand the analysis area setting 2, it is necessary to scan the sample surface with a focused beam to obtain an image of the sample surface. To obtain this image, for example, secondary electrons and fluorescence emitted from the sample surface by condensed beam irradiation are used. The yield of secondary electrons and fluorescence differs depending on the substance. While scanning the sample surface with a focused beam, the emission intensity of secondary electrons and fluorescence is determined for each irradiation position, and when the emission intensity is expressed on a two-dimensional plane as a function of the irradiation position, an image of the sample surface can be obtained. I can do it. Most simply, by scanning a fluorescent screen with the electron beam while applying brightness modulation corresponding to the emission intensity to the electron beam, an image of the sample surface can be projected on the fluorescent screen.

In acquiring this image, energy analysis of secondary electrons and fluorescence is not necessarily required. Furthermore, it is also possible to change the magnification rate of this image by changing the convergence state (for example, beam diameter) of the light beam on the sample surface.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) FIG. 1 is a block diagram showing the configuration of an analyzer according to a first example of the present invention.

Light in the vacuum ultraviolet region from soft X-rays emitted from a light source 1 is focused onto the surface of a sample 3 using an optical system 2 . Here, the light source 1 is monochromatic.

If the light source is not monochromatic, use a spectrometer or the like to make it monochromatic. In this case, the light source 1 is, for example, the exit slit of a spectrometer. Further, the optical system 2 is a reflective optical system. The optical system 2 may be composed of a single optical element or may be composed of a plurality of optical elements. The optical elements used here have been described above.

A sample 3 is placed on a sample stage 4. The sample stage 4 can be moved minutely in three dimensions by a moving mechanism 5. This minute movement is controlled by a control 10.

Particles released from the surface of sample 3 by focused beam irradiation (
electrons, photons, ions, neutral particles, etc.) are detected using a detector 6 and an analyzer 7. Here, the detector 6 is used for setting and grasping the analysis area, and a particle energy analysis function is not necessarily required. For example, it may be a simple secondary electron detector or a fluorescence detector. On the other hand, the analyzer 7 is an analyzer equipped with particle species and particle energy analysis functions.

Detector 6 and analyzer 7 are controlled by controllers 8 and 9, respectively.

In this embodiment, the moving mechanism 5 is used to move the sample 3 minutely relative to the focused beam, thereby scanning the focused beam on the surface of the sample 3. A particle detection signal from the detector 6 during this focused beam scanning is input to the signal processing device 11 via the controller 1-roller 8. Also, sample 3
A position signal indicating the focused beam irradiation position on the surface is also transmitted by the controller.
- input from the roller 10 to the signal processing device 11;

The signal processing device 11 stores particle detection signals at each irradiation position of the focused beam on the surface of the sample 3.

The particle detection signal and position signal stored in the signal processing device 11 are input to the signal generating device 12 . If signal processing is required before this input, the necessary signal processing can be performed within the signal processing device 11. The signal generator 12 generates a signal necessary for the display/input device 13 to obtain an image of the surface of the sample 3 based on the input signal. For example, when the display/input device 13 is a television screen, the signal generating device 12 generates a television signal based on the input signal from the signal processing device 11. As a result, an image of the surface of the sample 3 can be obtained on the display/input device 13.

Next, an analysis area is set based on the image of the surface of the sample 3 displayed on the display/input device 13.

In this setting, for example, the area (or point) to be analyzed
Input the coordinates of to the display/input device. Based on the input coordinates, the signal processing device 11 determines the corresponding analysis region on the surface of the sample 3 and sends a position control signal to the controller 1-roller 10. The controller 10 receives this position control signal, controls the moving mechanism 5, and moves the sample stage 4 and the sample 3 minutely so that the analysis region inputted by the display/input device 13 is irradiated with the focused beam.

Particles released from the surface of the sample 3 by irradiating the analysis area with light are observed using the analyzer 7. Here, analyzer 7
(as mentioned earlier) is an analyzer with particle species and energy analysis capabilities. The particle detection signal from the analyzer 7 is
is input to the signal processing device 11 via the controller 9,
be remembered.

The signals stored in the signal processing device are input to the signal generating device. If signal processing (to obtain desired data) is required before this input, this signal processing is performed within the signal processing device 11. The signal generating device 12 generates a signal necessary for displaying the analysis result on the display/cutting device 13 based on the input signal. As a result, the display/input device 13 displays the analysis results such as element types and atomic bonding states in the analysis region on the surface of the sample 3.

In this embodiment, it is also possible to obtain information regarding the distribution state such as the distribution of element species within a designated region. In this case, for example, based on the image of the surface of the sample 3, a set of coordinate values specifying the outline of the area to be analyzed is input from the display/input device. As described above, the signal processing device 1
1 determines the corresponding analysis area on the surface of the sample 3 and sends a position control signal to the controller 10. The controller 10 receives this position control signal, controls the moving mechanism 5, and continuously moves the sample stage 4 and sample 3 in a minute position so that the focused beam scans within the analysis area specified by the display/input device 13. Moving. The particle detection signal from the analyzer 7 at this time and the corresponding position signal are stored in the signal processing device 11. The subsequent signal processing and display of observation results are the same as in the case of determining the analysis area setting 2. Changes in the analysis/observation mode, etc. are performed by inputting from the display/input device 13.

According to this embodiment, since the analysis area can be set 2 and understood based on the image of the surface of the sample 3, the surface analysis of a minute area can be performed easily and accurately. Furthermore, by scanning the focused beam over the surface of the sample 3, accurate distribution of element types and atomic bonding states can be easily obtained.

(Example 2) In order to obtain an image of the surface of the sample 3, the sample 3 is
It is necessary to scan over the surface. This focused beam scanning is also necessary to obtain the distribution of specific element species and atomic bonding states on the surface of the sample 3. In Example 1, the focused beam scanning for this purpose was achieved by slightly moving the sample 3 with respect to the focused beam. However, scanning the focused beam on the surface of the sample 3 can also be achieved using other methods.

An example of this is shown in FIG. In Figure 2, optical system 2
is installed on the moving mechanism 14. The moving mechanism 14 is controlled by a controller 1 and roller] 5, and is capable of fine three-dimensional movement.

In this embodiment, the optical system 2 is slightly moved relative to the sample 3 to scan the focused beam on the surface of the sample 3. The controller 15 plays substantially the same role as the controller board o in the first embodiment and has similar functions. The other parts are the same as in the first embodiment.

In this example as well, the same effects as in Example 1 can be obtained.

(Example 3) FIG. 3 also shows another method of scanning the focused beam on the surface of the sample 3. In this embodiment, the focused beam from the optical system 2 is reflected by the reflecting mirror 16 and then enters the surface of the sample 3. At this time, by changing the angle of the reflecting mirror 16 with respect to the optical axis of the optical system 2, it is possible to scan the surface of the sample 3 with the focused beam.

The angle of the reflecting mirror 16 is changed using a drive mechanism 17 controlled by a controller 18.

From the controller 18, a position signal corresponding to the angle change and therefore the position of the focused beam on the surface of the sample 3 is sent to the signal processing device 11 (1G). This controller]-8 plays substantially the same role as the controller 10 of the first embodiment and has similar functions. The other parts are the same as in the first embodiment.

In this example as well, the same effects as in Example 1 can be obtained.

(Embodiment 4) FIG. 4 also shows another method of scanning the focused beam on the surface of the sample 3. In this embodiment, particles generated by a particle source 19 are accelerated and focused using an acceleration/focus/deflection system 20 and are irradiated onto a target 21 . Here, the particles may be, for example, charged particles (electrons, ions). Alternatively, laser light may be used. However, when laser light is used, particle acceleration means is not required in the acceleration/convergence/deflection system 20.

By irradiating particles onto the target 21, light in the range from soft X-rays to vacuum ultraviolet is generated from the target surface. This light is focused by the optical system 2 and irradiated onto the surface of the sample 3. This light is used for understanding the analysis area setting 2 and for surface analysis.

The focused beam scans on the surface of the sample 3 by changing the light generation position on the target 21. In order to change the generation position of this light, the acceleration/convergence/deflection system 2
0 to deflect the particles from source 19 (while keeping them focused). That is, the surface of the target 21 is scanned with a particle beam from the particle source 19. This particle beam scanning changes the light generation position on the surface of the target 21, and as a result, it becomes possible to scan the surface of the sample 3 with the focused beam.

The scanning of the particle beam on the surface of the target 21 is controlled by a controller 22 . From the controller 1-roller 22, a position signal corresponding to the irradiation position of the particle beam, and therefore the irradiation position of the focused beam on the surface of the sample 3, is sent to the signal processing device 1.
− direction is sent out. This controller roller 22 plays substantially the same role as the controller roller 10 of the first embodiment and has similar functions. The other parts are the same as in the first embodiment.

In this embodiment, the particle beam is irradiated onto the back surfaces of targeters 1 to 21. However, if the target material is a thick material, the particle beam is irradiated onto the surface of the target material. It is assumed that the direction from which the target material is irradiated with the particle beam can be determined as necessary.

In this example as well, the same effects as in Example 1 can be obtained.

The embodiments of the present invention have been described above. It goes without saying that combinations of the embodiments shown here are included in the present invention.

Furthermore, the purpose of the present invention is to achieve a movement accuracy of 0,01 μm or less, which can be achieved by, for example, an actuator using a piezo element.

〔Effect of the invention〕

According to the present invention, the analysis area can be set 9 and grasped based on the image of the sample surface. As a result, surface analysis of minute regions can be performed with high precision.

[Brief explanation of the drawing]

1 to 4 are block diagrams of an analyzer according to an embodiment of the present invention. 1... Light source, 2... Optical system, 3... Sample, 4...
・Sample stage, 5...Movement mechanism, 6...Detector, 7...
・Analyzer, 8,9゜10...Controller, 11...
- Signal processing device, 12... Signal generation device, 13...
Display/input device, 14... Movement mechanism, 15... Controller, 16... Reflector, 17... Drive mechanism, 18
... Controller, 19... Particle source, 20... Acceleration/convergence/deflection system, 21... Target, 22... Controller.

Claims (1)

[Claims] 1. In surface analysis, in which light in the vacuum ultraviolet region from soft X-rays is focused and irradiated onto the sample surface, and particles released from the sample surface are observed by this light irradiation, the sample is A surface analysis method characterized by setting and understanding points or areas to be analyzed using an image of the sample surface obtained by scanning the surface. 2. The surface analysis method according to claim 1, wherein the light is focused using a reflective optical element or an optical system. 3. The surface analysis method according to claim 2, wherein the scanning of the light on the sample surface is achieved by controlled micro-movement of the sample. 4. The surface analysis method according to claim 2, wherein the scanning of the light on the sample surface is achieved by controlled micro-movement of a condensing optical system or an optical element. 5. The surface analysis method according to claim 2, wherein the scanning of the light on the sample surface is achieved by controlled micro-movement of a light source. 6. The surface analysis method according to claim 5, wherein the minute movement of the light source is performed by scanning a charged particle beam on the target material. 7. The surface analysis method according to claim 5, wherein the minute movement of the light source is performed by scanning a laser beam on the target material. 8. Claim 2, wherein the scanning of the light on the sample surface is achieved by controlled angle changes of a reflecting mirror installed in the middle of the optical path.
Surface analysis method described in section. 9. The surface analysis method according to claim 3, wherein the image of the sample surface is a secondary electron image of the sample surface. 10. The surface analysis method according to claims 3 to 8, wherein the image of the sample surface is a fluorescence image of the sample surface. 11. The surface analysis method according to claims 3 to 10, wherein the analysis points or regions are set using coordinates on an image of the sample surface. 12. Claims 9 and 10, wherein the surface analysis is performed by observing electrons or photons emitted from the sample surface.
Surface analysis method described in section. 13. Claims 9 and 10, wherein the surface analysis is performed by observing the energy of electrons emitted from the sample surface.
Surface analysis method described in section. 14. The surface analysis method according to any one of claims 9 to 13, wherein the distribution measurement within a specific region on the sample surface is performed by scanning the sample surface with light. 15. A surface analysis device comprising a means for generating light in the vacuum ultraviolet region from soft X-rays, a means for focusing this light on a sample surface, and a means for observing particles emitted from the sample surface by light irradiation,
A means for scanning the above-mentioned light on the sample surface, a means for forming an image of the sample surface from the above-mentioned particle observation signal during this light scanning, and a means for setting an analysis point or area based on the image of the sample surface are added. surface analysis device. 16. The surface analysis device according to claim 15, wherein the light condensing means is a reflective optical element or an optical system. 17. The surface analysis apparatus according to claim 16, wherein the light scanning means is a controlled micro-moving means for the sample. 18. The surface analysis apparatus according to claim 16, wherein the light scanning means is a condensing optical element or a controlled minute movement means of an optical system. 19. The surface analysis apparatus according to claim 16, wherein the light scanning means is a controlled minute movement means for a light source. 20. The surface analysis apparatus according to claim 19, wherein the micro-moving means for the light source is means for scanning a charged particle beam on the target material. 21. The surface analysis apparatus according to claim 19, wherein the micro-moving means for the light source is means for scanning a laser beam on the target material. 22. The surface analysis apparatus according to claim 16, wherein the light scanning means is a reflecting mirror installed in the middle of the optical path, and a controlled angle changing means for this reflecting mirror. 23. Claims 17 to 22, wherein the means for forming an image of the sample surface is a means for forming a secondary electron image of the sample surface.
The surface analysis device described in Section 1. 24. The surface analysis apparatus according to any one of claims 17 to 22, wherein the means for forming an image of the sample surface is a means for forming a fluorescent image of the sample surface. 25. Claims 17 to 2, wherein the means for setting the analysis point or area is means for inputting coordinates on an image of the sample surface.
The surface analysis device according to item 4. 26. The surface analysis apparatus according to claim 23 or 24, wherein the surface analysis is performed by observing electrons or photons emitted from the sample surface. 27. The surface analysis apparatus according to claim 23 or 24, wherein the surface analysis is performed by observing the energy of electrons emitted from the sample surface. 28. Claims 23 to 27, wherein the distribution can be measured within a specific area on the sample surface by scanning light on the sample surface.
The surface analysis device described in Section 1.