JPS62113350A - Electron microscope - Google Patents

Abstract

PURPOSE:To make both energy filter and unfilter images observable at equi- magnification, by installing a transfer lens in vertical symmetrical positions of a spectrometer of an electron microscope securing the energy filter image. CONSTITUTION:Electron beams 2 transmitting a sample is led into spectrometers 10a-10c and dispersed according to an energy value and, after the image 23 is accorded with the axis of an electron microscope, an energy filter image 20 is secured on a screen 17. At this time, a transfer lens 22 is set up on an optical axis of the electron microscope on vertical symmetrical axes of these spectrometers 10a-10c. And, when an unfilter image is observed, the transfer lens 22 is excited, forming a transmitting electron image in a position of the image 23. Therefore, both energy filter and unfilter images are usable in selection and, what is more, these images are observable at equi-magnification.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) Kikomei relates to an electron microscope, and more specifically to an electron microscope that can be used for both energy analysis and electron microscopy.

(Prior art) Energy filters are used in electron microscopes when an electron beam is irradiated onto a sample, and the electron beam loses some of its energy due to interaction with the sample. Since unique spectra are obtained depending on the elements that make up the sample, this device performs elemental analysis by observing this energy loss spectrum. FIG. 2 is a schematic diagram of an electron microscope equipped with a conventional energy filter. 1 is an electron gun; 2 is an electron beam emitted from the electron gun; the electron beam 2 is focused by a focusing lens 3 and irradiates a sample 4; an objective lens 5 forms a transmission electron image 6 of the sample; A lens 7 forms an incident point 8 and an incident image 9, and electrons 1! i12 spectrometer ioa, 1o
b. Leading to ioC.

Uniform magnetic fields in opposite directions are applied to Spectros 5-10a, 10c, and 10b to deflect the electron beam 2, disperse energy, and return it to the original optical axis 11. A typical energy analyzer uses one spectrometer to emit electrons and an electron beam perpendicular to the axis of the microscope and enter the detector, but the device shown in FIG. 2 uses three spectrometers 10a.

The reason why 10b and 10c are used is to align the electron Fi12 with the axis of the electron microscope and use it in conjunction with spectrum analysis and ordinary electron gi1m&R.

Returning to the explanation of the apparatus shown in Fig. 2, the electron beam 2 is dispersed according to the F energy value of the spectrometers 10a, 10b, 10c. Although it is distributed by
A portion of the spectrometer is focused to produce a colorless portion.

The image 12 formed in the subek 1-rometer 10c is an image formed by converging dispersed electron beams of various energy values, and is colorless and is called achromatic image. An energy loss spectrum 13 is also formed below the spectrometer 10c, which is an image of chromatic dispersion. ), the intermediate lens 15 is used to focus on the chromatic image 12, and the projection lens 16 is used to enlarge and project the energy filter @1B onto the screen 17.

Incidentally, FIG. 3 shows an electron microscope image (unfiltered image) when no energy filter is used. Energy filter 10a in FIG.

When the excitation of 10b and 10C is turned off, the incident lens 7 forms the transmitted electron image 6 as an enlarged image 19 at the position of the chromatic image 12 in FIG. Since the distance from the input lens 7 to the magnified image 19 is long, the magnification ratio of magnification B419 is (
! ! The image is much larger than the image 12 before it disappears. For this reason, even when electrically switching between obtaining an energy filter image and obtaining an unfiltered image, a large magnification difference occurs between the two images.

(Problems to be Solved by the Invention) As described above, in an electron microscope equipped with an energy filter, an energy filter image is captured through the energy filter. If you switch between using an electron microscope and an ordinary electron microscope, the magnification of the image will be significantly different, making observation difficult and requiring adjustments to change the magnification of the electron lens each time. It is inconvenient.

The present invention has been made in view of the above points, and its purpose is to eliminate the difference in magnification when observing an energy filtered image and an unfiltered image by electrically switching the energy filter on and off. The objective is to eliminate the inconvenience of adjusting the magnification of the lens each time.

(Means for Solving the Problems) The present invention, which solves the above problems, separates electron beams from a sample according to their energy. ! ! In an electron microscope that is equipped with several spectrometers and is used by switching between energy filter arrays and unfiltered images, a transfer lens is installed at a vertically symmetrical position of the spectrometers, and an unfiltered image of the same size as the energy filter image is generated by 1q. It is characterized by:

<Function> In the present invention, when switching between the energy filter 19 and the unfiltered image, the transformer 771 lens is excited to make the energy filtered image and the unfiltered image the same magnification.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention including a spectrometer 10a,
10b and 10c are turned off to obtain an unfiltered image. This is a schematic configuration diagram showing the normal operation of an electron microscope. Since the same parts in the figure as in FIG. 2 are designated by the same reference numerals, repeated explanation will be avoided. 21 are spectrometers 10a, 10b,
This is the mechanical vertical symmetry axis of 10c, and the transnor lens 221 is installed on the vertical symmetry axis 21 of the spectrometer. The transfer lens 22 is excited 1i only when observing an unfiltered image with a lens having a magnification of 1, and transfers the incident image 9 to the position of the color erasing image 12 in FIG. 2 at the same magnification to form transmitted electrons fg123. At this time, the focal length of the transfer lens 21 is 111 [ft is f t −#/4
... (1) (where i is the distance from the position of the incident image 9 to the position of the color erasing image 12 in Fig. 2) If the focal length is 4/4 and the subject is placed at a position twice the focal length, (1 ) from the formula 1/f t -1/2f t 71/2f
t...(2) ft in the first term on the left side is the focal length, 2ft in the second term is the position of the subject from the lens, and 2f on the right side
t is the position of the image from the lens. From equation (2), the image is located at a position equal to the distance between the lens and the object on the opposite side of the lens, and the magnification is 1.

From the above explanation, since the transmitted electron @ 23 is imaged at the position of the color disappearing image 12 in FIG.
An image of the same size as 8 is obtained. Note that the above is just an example, and for example, the position where the image is formed by the transfer lens 22 may be the position of the energy filter image in FIG. 2. Also, people! 1FJfi instead of 9, input point 8
may be transferred.

(Effects of the Invention) As described above in detail, according to the present invention, even when switching between an energy filtered image and an unfiltered image, imaging can be avoided without changing the magnification.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an electron microscope equipped with an energy filter according to an embodiment of the present invention in an unfiltered state, FIG. 2 is a schematic configuration diagram of an electron microscope equipped with a conventional energy filter, and FIG. 1 is a schematic configuration diagram of an electron microscope equipped with an energy filter in an unfiltered state. 1... Electron gun 2... Electron beam 3... Focusing lens 4... Sample 5... Objective lens
6...Transmission electron image 7...Incidence lens 8
...Incidence point 9...Incidence images 10a, 10b, 10c...Spectrometer 1
1... Optical axis 12... Color erasure 13...
Energy loss spectrum 14... Energy selection slit 15... Intermediate lens 16... Projection lens 17
...Screen 18...Energy filter image 19...Enlarged (g! 20...Projected image 21
... Spectrometer's vertical symmetry axis 22 ... Transfer lens patent applicant JEOL Co., Ltd. Representative Patent attorney Fuji Ijima and one other person Figure 3] 9. Enlarged image 1st section]; Electron gun 2; Electron beam 3; Focusing lens 4; Sample 5: Objective lens 61 Transmission electron image 7; Incident lens 87; Lens]6. Projection lens] 7; Screen 20; During incidence 9, incident image, 10b, 10c + spectrometer] 1; optical axis] 2; color extinction] 3; energy loss spectrum] 4; energy selection slit) 5. Medium l lens 16.8 shadow lens]7. Screen] 8. energy filter tie 9

Claims (1)

[Claims] In an electron microscope that is equipped with multiple spectrometers that separate electron beams from a sample according to their energy, and is used by switching between energy-filtered and unfiltered images, a transfer lens is installed at a symmetrical position above and below the spectrometers. An electron microscope characterized by obtaining an unfiltered image of the same size as an energy filtered image.