JPH1021863A - Local analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an image from being vibrated from a periphery of a mirror cylinder by bring an arm expanding from another position than a stage mounting portion into contact with a holder fixing a sample held on a sample stage or the sample and integrating the mirror cylinder and the sample. SOLUTION: After appropriate positional alignment of a sample 4, a tail portion is fixed to a mirror cylinder, and a tip end is expanded into the mirror cylinder, a tip end portion 12 of an expandable vibration proof arm 10 is pressed and brought into contact with the sample 4 or a sample holder 5 and fixed to a sample stage 6. An insulation base 15 is incorporated between the tip end portion 12 of the vibration proof arm 10 and a shaft 11 so as to measure sample current, and a spring 14 is intervened between the tip end portion 12 and the shaft 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local analyzer for irradiating a local area on a sample with an electron beam to observe and analyze a high-magnification image.

[0002]

2. Description of the Related Art A local analyzer using an electron beam, such as an electron microscope, an X-ray microanalyzer (EPMA), and an Auger electron spectrometer (AES), can obtain the surface shape, crystal state, and element information of a minute region. Therefore, it is widely used for material research. And with the development of material research, analysis of smaller areas has been required,
Efforts to improve spatial resolution are continuing. Actually, in AES (hereinafter abbreviated as FE-AES) equipped with a field emission type electron gun, the beam can be narrowed down to about 15 nm and element analysis can be performed.

As described above, when a high-magnification image such as 100,000 times is photographed and analyzed, the influence of vibration becomes a serious problem in practical use. When vibration occurs, the beam and the sample cause a relative displacement, and the effect appears as a blur of an image or a displacement of an analysis position. This problem is particularly serious in an apparatus such as EPMA and AES in which the drive of the stage is high.
This is for the following reason.

[0004] EPMA and AES use X, X
There is a case where the analysis is performed by largely moving, rotating, or tilting in the Y and Z directions. That is, in the case of EPMA, there is a method called mapping that takes in the intensity of X-rays generated from the sample by the primary beam while driving the stage in the X and Y directions to obtain a two-dimensional intensity distribution. For this purpose, the sample stage must be able to be driven freely within a large range of several tens of mm. Also, in the case of AES, in addition to driving for alignment, it is required to be able to tilt and rotate the sample, which is necessary for ion sputtering and charge-up reduction. Furthermore, as a measurement function unique to the AES apparatus, there is a depth analysis by combining ion sputtering of a sample and an electron beam. In many cases, the resolution in the depth direction is improved by smoothing the bottom of the crater of the sample by ion sputtering. Therefore, it is required to freely rotate the sample at a rotation speed of about 1 rpm.

[0005] Therefore, in these apparatuses, the sample is mounted on the upper part of the sample stage provided with a mechanism for rotating and tilting the three axes of X, Y and Z. When viewed from the whole apparatus, the sample is located in the analysis chamber. It will be located at the free end protruding into the space. Such a structure is very susceptible to vibration. Even when the vibration from the surroundings is suppressed, since the vibration resonance point also exists in the rigid body of the device, it is difficult to actually completely stop the vibration of the above-described structure. Providing mechanical play or making the sample stage easier to slide to improve the drivability of the sample stage is also a weak point against vibration.

In a transmission electron microscope capable of photographing an image of the highest magnification as an electron beam image, there is no need to move the sample greatly in the apparatus, and the sample is fixed inside the lens barrel and integrated with the lens barrel. However, it is possible to sufficiently cope with only the conventional measures against vibration. On the other hand, in an apparatus such as FE-AES for moving a sample on the sample stage as described above, although the beam can be narrowed down very much by the improvement of the electron gun, the substantial resolution of the obtained image is obtained. Is
Due to the vibration, the value is much larger than the beam diameter. Therefore, in these devices, the influence of vibration is a major problem in improving spatial resolution.

[0007]

The first principle of preventing the influence of such vibration is to eliminate the vibration source, and the second is to provide vibration isolation between the vibration source and the object. . In this case, as the vibration source, it is necessary to consider the vibration itself transmitted through the floor and the wall and the effect of the sound transmitted through the air. For example, Japanese Patent Application Laid-Open No. 1-35839 discloses that an exhaust system, a cooling fan, and the like, which are sources of vibration or sound around the apparatus, are stopped at a high magnification. However, it is not possible to completely eliminate vibrations and sounds generated on the floor due to shaking and other parts of the room.

In addition, in terms of providing vibration isolation between a vibration source and a target object, a vibration isolation table using an air spring, a metal spring, rubber, or the like, or a magnetic levitation type vibration isolation table has been widely used. . Japanese Patent Laid-Open No. 2-203 discloses a vibration isolation table for actively canceling and preventing vibration.
Various improvements have been made as typified by Japanese Patent No. 941. However, these anti-vibration tables also have the purpose of preventing vibrations from the floor, and therefore cannot prevent the effects of sound, which is vibrations transmitted through the air. In order to prevent the influence of sound, it is often the case to take measures such as covering the periphery of the analyzer with a blackout curtain or a soundproof wall. However, these countermeasures are not only expensive and require a large space, but also it is difficult to completely prevent the vibration of the sample held on the sample stage as described above.

The present invention solves such a problem and provides an EPM.
It is an object of the present invention to provide a practical and simple mechanism for preventing the influence of vibration without losing the driveability and functionality of a stage required in A, AES, SEM and the like.

[0010]

SUMMARY OF THE INVENTION The present invention is applied to a local analyzer for analyzing a minute area using an electron beam. An arm extending from a position different from the stage mounting portion is brought into contact with a holder or a sample on which the sample held on the sample stage is fixed, so that the lens barrel generating the primary beam and the sample are integrated. This prevents an image from being affected by vibration generated around the lens barrel. Further, at this time, an insulator is incorporated in a part of the arm so as not to hinder the sample current measurement even when the arm is in contact. In addition, the apparatus incorporates a spring into the arm so that the analysis position can be easily adjusted and the contact portion can be prevented from being damaged.

In other words, the present invention relates to a local analyzer for analyzing a minute area using an electron beam, a telescopic anti-vibration arm having a tail fixed to a lens barrel and an extensible tip extending into the lens barrel; A local analyzer comprising a sample fixing holder held on a sample stage or a pressing and fixing device for pressing a tip against a sample to integrate the lens barrel and the sample.

In this device, the arm preferably includes a spring for biasing the distal end in the extension direction, and the arm has an electrically insulating material interposed between the distal end and the tail end. Preferably, the tip is electrically coupled to the sample.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as a means for preventing vibration most reliably, a sample vibration isolator is used in the apparatus to integrate it with a lens barrel, while maintaining a sample handling function. The present invention will be described in detail based on an example in which FE-AES is used as the local analysis device.

FIG. 1 shows an embodiment of the present invention. FE-AE
S is generally a field emission type electron gun 1, an energy analyzer 2,
It comprises an analysis chamber 3, a sample stage 6, and a vacuum evacuation system (ion pump) 9. On the sample stage 6, a sample holder 5 on which the sample 4 is fixed is set. Such FE-
In the AES, the anti-vibration device according to the present invention inserts the anti-vibration arm 10 into the analysis chamber 3 from a direction different from that of the sample stage 6 and brings the sample 4 or the sample holder 5 into contact with the tip end thereof, and It is integrated with the wall of the analysis chamber 3 to suppress vibration. The anti-vibration arm 10 is provided with a pressing and fixing device 20 so that positioning can be performed from outside the device. The pressing and fixing device 20 has a mechanism for driving the anti-vibration arm and locking the anti-vibration arm.

The operation of the anti-vibration mechanism according to the present invention is as follows. After the sample 4 is roughly aligned, the tip 12 of the anti-vibration arm 10 is pressed against the sample 4 or the sample holder 5 to fix the sample stage 6. . An insulating table 15 is incorporated between the end portion 12 of the anti-vibration arm 10 and the shaft 11 so that a sample current can be measured. Also, a spring 1 is provided between the tip 12 and the shaft 11 in consideration of the workability of the alignment.
4 is interposed. As a result, high-magnification measurement of 50,000 times or more can be performed with almost no influence of vibration.

A description will now be given of an operation for actually implementing the present invention. Before the anti-vibration arm 10 is brought into contact with the sample 4, an analysis position is searched for by a secondary electron image several hundred times to several thousand times. When the position is determined, the tip 12 of the vibration-proof arm 10 is brought into pressure contact with the sample 4 or the sample holder 5. The anti-vibration arm 10 finely adjusts the position and the pressing force of the sample stage 6 and the anti-vibration arm 10 while taking the analysis position as close to the center as possible. If the pressure contact of the anti-vibration arm 10 is weak, even a high magnification of tens of thousands times, it is impossible to suppress vibration of about several tens nm which is a problem. For this reason, it is necessary to apply some pressure. If the analysis position is not at the center, there is a method of electrically shifting the beam, but it is necessary to avoid bending the beam as much as possible from the point of narrowing the beam.
Therefore, it is necessary to move and adjust the sample stage so that the analysis position is at the center. In this case, the conductors are pressed against each other with considerable force, so that the structure must not be overloaded. The anti-vibration arm 10 incorporating the spring 14 having a large spring constant can perform alignment without damaging the sample stage 6.

At the time of analysis, it is required to measure the sample current (beam current) to confirm the analysis conditions. If the anti-vibration arm 10 is entirely made of metal, the current cannot be measured because the current flows to the ground through the anti-vibration arm. Therefore, an insulating table 1
5 is cared for and insulated. FIG. 2 is a schematic diagram showing a state at the time of measurement. When the sample 4 is irradiated with the electron beam 24, the secondary electrons 21 are distributed in a considerably wide range in front of the sample 4. In this distribution, even when the tip end portion 12 of the anti-vibration arm 10 which is electrically insulated, even if it is a metal, approaches a certain potential. The secondary electron detector (SED) 7
Although the secondary electrons 21 are taken in by applying a drawing voltage, the energy of the secondary electrons is very weak.
With the movement of the zero end portion 12, the distribution of secondary electrons is affected. In order to avoid this, it is preferable that the distal end portion 12 of the anti-vibration arm 10 be electrically connected to the sample 4 by the conducting wire 23. In addition, 22 in FIG. 2 is an ammeter.

[0018]

According to the image before the present invention is carried out, the image blurring having a maximum amplitude of about 40 nm occurs due to vibration.
With the local analyzer of the present invention, image blur could be reliably suppressed to 10 nm or less.

[Brief description of the drawings]

FIG. 1 is an apparatus configuration diagram of an embodiment (FE-AES) of the present invention.

FIG. 2 is an explanatory diagram of insulation of a vibration isolation mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun 2 Energy analyzer 3 Analysis room 4 Sample 5 Sample holder 6 Sample stage 7 SED 9 Vacuum exhaust system (ion pump) 10 Anti-vibration arm 11 Shaft 12 Tip part 14 Spring 15 Insulating stand 20 Press-fixing device 21 Secondary electron 22 Ammeter 23 Conductor 24 Electron beam

 ──────────────────────────────────────────────────の Continued on the front page (72) Kimi Yamamoto 1st Kawasaki-cho, Chuo-ku, Chiba City Kawasaki Steel Engineering Co., Ltd.

Claims (3)

[Claims] 1. A local analysis apparatus for analyzing a microscopic area using an electron beam, wherein a tail portion is fixed to a lens barrel, and a tip is extended into the lens barrel, and is expandable and contractable. A local fixing device comprising: a sample fixing holder held on a sample stage or a sample fixing holder or a pressing and fixing device for integrating the sample with the lens barrel by pressing the sample. 2. The local analysis apparatus according to claim 1, wherein the vibration isolating arm includes a spring that urges a distal end in an extension direction. 3. The localization device according to claim 1, wherein the vibration-isolating arm has an insulator interposed between a tip end and a tail end, and the tip is electrically connected to the sample. Analysis equipment.