JP2000277044A - Scanning electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means and a method which can easily perform a crystal orientation and crystal structure analysis with an EBSP(electron back-scattered deflection pattern) detector by using an exclusive sample folder. SOLUTION: A sample folder capable of fixing an exclusive resin embedded sample having an optimal inclination angle to detect elastically scattered reflection electrons and equipped with an EBSP detector calibration sample 20 fixation part and a Faraday cup 23 is used. Easy view movement becomes possible by combining the special sample folder 7 and a motor drive sample stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning electron microscope which is most suitable for an apparatus for irradiating a sample with an electron beam and observing a diffraction image (Kikuchi pattern) projected by elastic scattering reflected electrons generated from the sample.

[0002]

2. Description of the Related Art EBSP is one of the crystal structure analysis methods.
(EBSD) device (E lectron B ackscattered D iffractio
n P attern: there is hereinafter referred to as EBSP). The EBSP device has been conventionally used for a scanning electron microscope (Scanning Electron Microscope).
scorpe (hereinafter abbreviated as SEM), irradiates the surface of the sample with a focused electron beam, and projects a diffraction image of the elastic scattering reflected electrons generated from the sample surface based on the crystal orientation onto a screen.・ Able to analyze crystal structure.

In the EBSP detector, a fluorescent screen is arranged at the tip of a high-sensitivity CCD camera, and a diffraction image is projected on the fluorescent screen by elastic scattered reflected electrons, and the diffraction image is detected by the high-sensitivity camera to determine the crystal orientation and structure. Observe. For this reason, the EBSP detector is arranged right beside the sample. In addition, the sample is tilted by about 70 degrees to irradiate the surface of the sample with an electron beam and efficiently transmit the elastic scattering reflected electrons generated from the sample surface to the EBSP detector. For this reason, depending on the sample stage, if the stage is tilted by 70 degrees, the base of the sample stage will come into contact with the high-sensitivity CCD camera of the EBSP detector or the fluorescent screen that is the EBSP detector. May come into contact with the lens (objective lens).

[0004] Further, by retrofitting a sample stage with an inclination of about 70 degrees, the sample becomes non-eucentric, and if the stage is tilted or the stage is moved, the observation field of view may escape, and it may be troublesome to find the field of view. In addition, it is necessary to polish the sample surface in order to carry out EBSP analysis of the crystal orientation, structure, etc. of a metal or the like.

In general, a sample is embedded in a resin and the surface is polished with a microtome or the like and observed.

However, embedding the sample in a resin results in the sample becoming thicker. A general EBSP sample is assumed to be a thin sample, and there is no sample stage on which a thick sample can be placed. Therefore, E of a thick sample embedded in resin
BSP analysis was difficult. When performing more accurate EBSP analysis, in order to ensure a constant distance between the position of the sample and the EBSP detector (fluorescent screen surface), a standard sample (eg, Ge or Si) having a known crystal spacing is used each time. Calibration had to be performed, and each time the sample had to be replaced.

On the other hand, since the sample holder is not a standard sample holder, the sample holder is not included in the operation menu (dialog menu) of the scanning electron microscope, which is a general PC (personal computer) control, and the stage can not be driven by the PC control. Was.

[0008]

SUMMARY OF THE INVENTION When analyzing the crystal orientation and structure with an EBSP detector, it is possible to reduce troublesome operations such as tilting the stage and searching for a visual field, and to reduce the sample stage and the EBSP.
Preventing contact between detector and objective lens and EBSP
An object of the present invention is to eliminate the work of exchanging a sample between a calibration sample and an analysis sample of a detector, and to simultaneously perform sample current measurement. Another problem is that the analysis sample can be mounted even with a thick sample such as resin embedding.

Another object of the present invention is to provide a dedicated sample chamber capable of maintaining the arrangement relationship between the sample surface of the sample holder and the EBSP detector at 90 degrees with respect to the movement axis of the drive stage. Furthermore, when the EBSP sample holder is selected in the above scanning electron microscope apparatus, the position of the sample or standard sample and the position of the Faraday cup and the like can be easily selected on a menu to enable the stage movement of the X, Y, and Z axes. It is in.

[0010]

The object of the present invention is to provide a sample holder which can hold a resin-embedded sample in a sample holder inclined at 70 degrees in advance, an EBSP calibration holder and a Faraday cup. A dedicated sample chamber capable of maintaining the arrangement relationship between the sample surface of the sample holder and the EBSP detector at 90 degrees with respect to the movement axis of the drive stage is provided. A combination and a dedicated operation menu are created to control the drive of each holder, and the movement of the entire sample holder can be achieved by controlling the X, Y, and Z axis movements.

[0011]

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

FIG. 1 is a schematic diagram showing an embodiment of the present invention. The scanning electron microscope is an embodiment described in claim 1 of the present invention.

In FIG. 1, an electron beam 2 taken out of an electron gun 1 is converged into a thin electron beam by a converging lens 3 and an objective lens 4, and is sampled (including a sample holder) by a deflection coil 6 connected to a scanning power supply 5. ) 7 is scanned. Signals such as secondary electrons, reflected electrons, elastic scattering reflected electrons, and light are generated from the sample by the irradiation of the electron beam. Usually, in the SEM, secondary electrons are detected by the secondary electron detector 8 during observation. The detected secondary electron signal is converted from a signal from the signal amplifier 9 through a video signal circuit 10 to a CRT 11.
Is input to the luminance modulation terminal, and a scanning image by the secondary electron signal can be observed. EB for EBSP analysis
SP detector (high sensitivity fluorescent screen + CCD camera) 1
In No. 2, a diffraction image is projected on a fluorescent screen by elastic scattering reflected electrons generated from the sample, and the diffraction image is detected by a high-sensitivity camera, and the crystal structure orientation can be observed through a camera control unit 13 and an analysis computer 14. ing. The EBSP detector 12 is arranged right next to the sample 7 in order to efficiently detect the elastically scattered reflected electrons.

In order to efficiently receive reflected electrons and to efficiently perform calculations from the obtained crystal patterns,
The sample surface of the inclined sample holder 7 also has a sample chamber 15 so that the positional relationship between the stage movement axis (X axis in FIG. 1) 16 and the EBSP detector 12 can be maintained vertically (90 degrees). .

FIG. 2 shows an embodiment of the special sample holder according to the first to sixth aspects of the present invention. Sample fixing part 2
By increasing the number of samples 1 and 22, for example, several or more analytical samples (resin-embedded samples) 24 having an outer diameter of about 30 mm and a height of about 20 mm can be fixedly held. The sample holder 7 shown in FIG. 2 this time is an illustration in a case where the number of the sample fixing portions is two. In the case of a normal sample (slice sample) 25, a sample table 26 made of aluminum or the like having substantially the same size as the resin-embedded sample 24 is fixed to the sample holder 7, and the slice sample 25 is fixed thereon and observed.
It is also possible to analyze. The resin embedded sample 27 is fixed from the rear of the sample holder 7 by the sample fixing screw 25.

An EBSP analysis calibration sample (Ge or Si or the like) 20 is placed in the same direction as the stage movement X-axis 16 and on the sample holder 7 in the sample fixing portions 21 and 22.
It is fixed so that it is on the same plane as. Thus, the visual field search of the calibration sample 20 and the analysis sample 24 can be performed only by moving the stage movement axis (X axis) 16. The sample current (probe current) measurement is also performed by the Faraday cup 23 installed in the same sample holder 7 in the same direction as the stage movement X-axis 16. The Faraday cup 23 can measure a sample current (probe current) on the same surface as the analysis sample (resin-embedded sample) 24, similarly to the calibration sample 20.

Thus, the position of each observation object can be moved only by moving the stage movement axis (X axis) 16 in the same axis direction. Further, the Faraday cup 22 includes the sample holder 7.
It is also important that the sample current (probe current) required for the EBSP analysis be measured instantaneously in the initial stage of the observation after the replacement of the sample holder 7 by arranging the sample at the center of the sample.

The dedicated sample holder is moved in combination with a dedicated motor-driven sample stage in combination with the X-axis 16, Y-axis.
The axis 17 and the Z axis 18 can be controlled.

FIG. 3 shows an example in which the stage control graphic menu 28 of the dedicated sample holder is provided in the SEM operation system. After attaching the sample holder 7 of the present invention to the SEM stage, the E
By selecting the BSP, a schematic diagram of the sample holder 7 is graphically displayed on the screen layout on the stage control graphic menu 28, and it is also possible to confirm what the current position of the sample holder 7 is in the SEM.

When a sample site to be observed and analyzed is selected on the sample position selection screen 30, each holder (analysis sample 2
4. Calibration sample 20 and Faraday cup 2
The center position of 2) is stored in the motor drive sample stage, and this memory position can be called up by selecting the designated holder, and it is possible to move to the designated center position of each holder. .

Further, even when the sample observation / analysis position is changed by moving the X, Y and Z axes in the observation / analysis, the data can be stored and reproduced by the stage memory menu 31 on the stage control graphic menu 28. .

[0022]

As described above, according to the present invention, E
When a crystal orientation, a structure, and the like are analyzed by the BSP detector, by using a holder inclined at 70 degrees in advance, the analysis can be performed without tilting the sample stage. Also,
Since this holder can fix several resin-embedded samples, analysis with resin-embedded samples can be easily performed.
By mounting a sample table made of aluminum or the like having substantially the same size on the resin-embedded sample portion and fixing a thin sample thereon, observation and analysis of a normal sample is also possible.

Further, since the calibration sample for the EBSP analysis and the Faraday cup can be simultaneously mounted on the holder, calibration of the EBSP and measurement of the sample current (probe current) can be performed without exchanging the sample.

The sample holder is mounted on a motor-driven sample stage, and the observation point can be automatically moved to each sample holder (or calibration sample / Faraday cup) set position by the motor-driven sample stage. The position of each holder set is stored by the motor drive device, so that the troublesome work of searching for the visual field is eliminated, and the possibility that the sample table or the like is brought into contact with the EBSP detector is eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a scanning electron microscope according to an embodiment of the present invention.

FIG. 2 is a schematic structural view of a dedicated sample holder according to one embodiment of the present invention.

FIG. 3 is a diagram showing an example in which a stage control graphic menu of a dedicated sample holder is provided in an SEM operation system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Electron beam, 3 ... Convergent lens, 4 ... Objective lens, 5 ... Scanning power supply, 6 ... Deflection coil, 7 ... Sample holder, 8 ... Secondary electron detector, 9 ... Signal amplifier, 10 ...
Video signal circuit, 11 CRT, 12 EBSP detector (fluorescent screen + high sensitivity CCD camera), 13 Camera control unit, 14 Computer for analysis, 15 Sample, 16 Stage moving axis (X axis), 17
... Stage moving axis (Y axis), 18 ... Stage moving axis (Z axis)
Axis), 20: Calibration sample, 21, 22, Sample fixing part, 23: Faraday cup, 24: Analysis sample (resin embedded sample), 25: Sample fixing screw, 26: Sample stand, 27: Normal sample (flake) (Sample), 28: stage control graphic menu, 29: sample size selection screen, 30: sample position selection screen, 31: stage memory menu.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaya Takashima 1040 Ichimo Ichiki, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Science Systems, Ltd. F-term in Hitachi Science Systems (reference) 5C001 AA01 AA04 AA05 CC04 5C033 UU03 UU04

Claims (6)

[Claims] 1. A scanning electron microscope having a detector capable of converging and irradiating an electron beam onto a surface of a sample and detecting elastic scattering reflected electrons generated from the surface of the sample by the irradiation of the electron beam, wherein a sample holder is set at 70 degrees. A scanning electron microscope characterized in that the stage can be tilted and driven by a dedicated auto stage. 2. A dedicated sample chamber capable of maintaining an arrangement relationship between a sample surface of the sample holder and a detector capable of detecting elastically scattered reflected electrons at 90 degrees with respect to a movement axis of a drive stage. The scanning electron microscope according to claim 1, wherein 3. The sample holder according to claim 1, wherein a plurality of resin-embedded samples can be fixed. If a sample table of a corresponding thickness is inserted in place of the resin-embedded sample, a commonly used sample can be mounted. 2. The method according to claim 1, wherein
Alternatively, the scanning electron microscope according to claim 2. 4. The apparatus according to claim 1, wherein said sample holder is capable of fixing a standard sample (calibration sample) required for detecting elastically scattered reflected electrons. Scanning electron microscope. 5. The sample holder according to claim 1, wherein the sample holder has a Faraday cup capable of measuring a sample current (probe current) required for detecting elastically scattered reflected electrons. The scanning electron microscope according to item. 6. The resin-embedded sample, the standard sample, and the Faraday cup in the sample holder are controlled by dedicated software, their positions can be stored and reproduced, and the limit range (limiter) of the stage movement can be controlled. The method according to any one of claims 1 to 5, wherein storing the information prevents interference or contact between the camera for detecting the elastically scattered reflected electrons, the sample holder, and a lens of the scanning electron microscope. The scanning electron microscope as described.